science.magazine.5691.2004-09-17
TRANSCRIPT
17 September 2004
Vol. 305 No. 5691Pages 1661–1856 $10
INSIDENORTH KOREANSCIENCE
INSIDENORTH KOREANSCIENCE
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1665
DEPARTMENTS
1671 SCIENCE ONLINE
1673 THIS WEEK IN SCIENCE
1677 EDITORIAL by Norman P. NeureiterTalking with North Korearelated Inside North Korean Science News section page 1696
1679 EDITORS’ CHOICE
1684 CONTACT SCIENCE
1687 NETWATCH
1791 NEW PRODUCTS
1802 SCIENCE CAREERS
NEWS OF THE WEEK
1688 MANAGING SCIENCE
House Votes to Kill Grants, Limit Travel toMeetings
1689 SPACE PROGRAM
Aiming for the Sun, Crashing to Earth
1689 SCIENCE POLICY
The Candidates Speak on Sciencerelated Science Express Presidential Forum
1691 MEDICINE
Possible New Role for BRCA2related Science Express Report by M. J. Daniels et al.
1691 SCIENCESCOPE
1692 DATA SECURITY
Report Upholds Public Access to Genetic Codes
1692 WOMEN IN SCIENCE
Harvard Faculty Decry Widening Gender Gap
1693 PALEOCEANOGRAPHY
Signs of a Warm, Ice-Free Arctic
1695 DRUG RESEARCH
Legislators Propose a Registry to Track Clinical Trials From Start to Finish
NEWS FOCUS
INSIDE NORTH KOREAN SCIENCErelated Editorial page 1677
1696 NORTH KOREA
Visiting the Hermit Kingdom
1696 SCIENTIFIC EXCHANGES
A Wary Pas de DeuxNukes for Windmills: Quixotic or Serious Proposition?The Ultimate, Exclusive LAN
1705 GEOCHEMISTRY
In Mass Extinction, Timing Is All related Report page 1760
1706 BIOTERRORISM
Biosecurity Goes Global
1709 RANDOM SAMPLES
LETTERS
1713 Hollywood, Climate Change, and the Public A.Balmford, A. Manica, L. Airey, L. Birkin, A. Oliver, J.Schleicher. Evidence for Taming of Cats T. Rothwell.Response J.-D. Vigne and J. Guilaine. Figuring Out WhatWorks in Education A. Fink
1715 Corrections and Clarifications
BOOKS ET AL.1716 ENVIRONMENT
Red Sky at Morning America and the Crisis of theGlobal Environment J. G. Speth, reviewed by P. Dasgupta
1716 ANTHROPOLOGY
Tsukiji The Fish Market at the Center of the WorldT. C. Bestor, reviewed by S. Gudeman
1717 Browsings
POLICY FORUM
1719 GENETICS
Ethical Aspects of ES Cell–Derived GametesG. Testa and J. Harris
PERSPECTIVES
1720 NEUROSCIENCE
Signposts to the Essence of LanguageM. Siegalrelated Report page 1779
1723 CELL BIOLOGY
Double Membrane FusionN. Pfanner, N. Wiedemann, C. Meisingerrelated Research Article page 1747
1724 CHEMISTRY
Japan Bats a TripleR. Westrelated Report page 1755
1725 CHEMISTRY
A Dash of Proline Makes Things SweetE. J. Sorensen and G. M. Sammisrelated Report page 1752
1726 BIOMEDICINE
Eosinophils in Asthma: Remodeling a Tangled TaleM. Wills-Karp and C. L. Karprelated Reports pages 1773 and 1776
1729 PLANETARY SCIENCE
Predicting the Sun’s Oxygen Isotope CompositionQ. Yinrelated Report page 1763
Contents continued
COVER Pohyon Temple, north of Pyongyang, and tissue culture experiments by Un SongGun (inset) illustrate North Korea’s ancient roots and scientific hopes. Its leaders are quietly encouraging scientists to seek foreign collaborations and funds. A special NewsFocus on science in North Korea begins on page 1696; see also the Editorial on page 1677.[Photos: Richard Stone]
1716
1706
Volume 30517 September 2004Number 5691
1693
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1667
REVIEWS1733 AGING
Living with the Past: Evolution, Development, and Patterns of DiseaseP. D. Gluckman and M. A. Hanson
1736 AGING
Inflammatory Exposure and Historical Changes in Human Life-SpansC. E. Finch and E. M. Crimmins
SCIENCE EXPRESS www.sciencexpress.org
SCIENCE POLICY
Bush and Kerry Offer Their Views on ScienceEDITORIAL: The Candidates SpeakDonald Kennedy
CHEMISTRY: How Do Small Water Clusters Bind an Excess Electron?N. I. Hammer, J.-W. Shin, J. M. Headrick, E. G. Diken, J. R. Roscioli, G. H.Weddle, M.A. Johnson
An excess electron in a small water cluster mainly resides with a water molecule that accepts hydrogenbonds from two others, resolving a long-standing question.
CHEMISTRY
Hydrated Electron Dynamics: From Clusters to BulkA. E. Bragg, J. R. R. Verlet, A. Kammrath, O. Cheshnovsky, D. M. Neumark
Electrons in Finite-Sized Water Cavities: Hydration Dynamics Observed in Real TimeD. H. Paik, I-R. Lee, D.-S. Yang, J. S. Baskin, A. H. Zewail
Photoelectron spectroscopy reveals that an excited electron in a water cluster relaxes rapidly and thentransfers energy to surrounding water molecules, disrupting their hydrogen bonding.
MEDICINE: Abnormal Cytokinesis in Cells Deficient in the Breast Cancer Susceptibility Protein BRCA2M. J. Daniels, Y. Wang, M. Lee, A. R. Venkitaraman
A protein that suppresses breast cancer may do so in part by ensuring that daughter cells separate properlyafter cell division. related News story page 1691
TECHNICAL COMMENT ABSTRACTS1715 PALEONTOLOGY
Comment on “The Early Evolution of the Tetrapod Humerus”P. E. Ahlberg full text at www.sciencemag.org/cgi/content/full/305/5691/1715c
Response to Comment on “The Early Evolution of the Tetrapod Humerus”M. I. Coates, N. H. Shubin, E. B. Daeschler full text at www.sciencemag.org/cgi/content/full/305/5691/1715d
BREVIA1741 APPLIED PHYSICS: Direct Sub-Angstrom Imaging of a Crystal Lattice
P. D. Nellist et al.Correcting for spherical aberrations in its imaging lens improves the resolution of a transmission elec-tron microscope to less than one angstrom.
RESEARCH ARTICLES1743 DEVELOPMENTAL BIOLOGY: Environmentally Induced Foregut Remodeling by
PHA-4/FoxA and DAF-12/NHR W. Ao, J. Gaudet, W. J. Kent, S. Muttumu, S. E. Mango
Clusters of genes activated in different cell types of the developing worm form a regulatorynetwork that directs foregut development in response to external stimuli.
1747 CELL BIOLOGY: Mitochondrial Fusion Intermediates Revealed in Vitro S. Meeusen, J. M. McCaffery, J. Nunnari
Mitochondria, the double membrane–bound organelles that generate energy for the cell, fuse with one anotherusing quite different mechanisms for joining the inner and outer membranes. related Perspective page 1723
REPORTS1752 CHEMISTRY: Two-Step Synthesis of Carbohydrates by Selective Aldol Reactions
A. B. Northrup and D. W. C. MacMillanA two-step sequence using proline as a catalyst greatly simplifies the synthesis of chirally pure hexosesugars from three achiral aldehyde precursors. related Perspective page 1725
1724&1755
Contents continued
1741
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1669
1786
1755 CHEMISTRY: A Stable Compound Containing a Silicon-Silicon Triple Bond A. Sekiguchi, R. Kinjo, M. Ichinohe
A compound containing a silicon-silicon triple bond, the silicon analog of an alkyne, is synthesizedand shown to form stable green crystals. related Perspective page 1724
1757 CHEMISTRY: A Linear, O-Coordinated η1-CO2 Bound to Uranium I. Castro-Rodriguez, H. Nakai, L. N. Zakharov, A. L. Rheingold, K. Meyer
In a new coordination mode, carbon dioxide can bond to a uranium complex end-on, through itsoxygen atom.
1760 GEOCHEMISTRY: Age and Timing of the Permian Mass Extinctions: U/Pb Dating ofClosed-System Zircons R. Mundil, K. R. Ludwig, I. Metcalfe, P. R. Renne
Zircons from ash beds, annealed and treated with HF acid, yield accurate and consistent datesfor the Permian Triassic extinction of 252.6 million years ago and confirm that it occurredwithin 300,000 years. related News story page 1705
1763 PLANETARY SCIENCE: Molecular Cloud Origin for the Oxygen Isotope Heterogeneityin the Solar System H. Yurimoto and K. Kuramoto
A model suggests that the characteristic oxygen isotopes of early meteorites are a result of ultravioletradiation of carbon monoxide, which was then transported on dust to inner parts of the solar systemrelated Perspective page 1729
1766 PALEOCLIMATE: Middle Miocene Southern Ocean Cooling and Antarctic Cryosphere Expansion A. E. Shevenell, J. P. Kennett, D. W. Lea
Changes in ocean circulation affected by Earth’s orbit, not low atmospheric CO2 levels, may have initiatedthe expansion of Antarctic ice sheets 14 million years ago.
1770 STRUCTURAL BIOLOGY: Crystal Structure of a Shark Single-Domain Antibody V Region inComplex with Lysozyme R. L. Stanfield, H. Dooley, M. F. Flajnik, I. A. Wilson
Single-chain antibodies from the nurse shark contain two antigen-recognizing regions, whereas mammalshave three, yet the shark antibodies bind just as tightly.
BIOMEDICINE1773 Defining a Link with Asthma in Mice Congenitally Deficient in Eosinophils
J. J. Lee et al.1776 A Critical Role for Eosinophils in Allergic Airways Remodeling
A. A. Humbles et al.An immune cell that appears in the mouse lung during asthma-like attacks seems to cause rapid lungdysfunction and later to produce changes in lung structure. related Perspective page 1726
1779 NEUROSCIENCE: Children Creating Core Properties of Language: Evidence from an EmergingSign Language in Nicaragua A. Senghas, S. Kita, A. Özyürek
A sign language developed by deaf children consists of discrete units similar to those of spoken language,perhaps reflecting the fundamental organization of the brain’s language centers. related Perspective page 1720
1782 CELL BIOLOGY: Two Distinct Actin Networks Drive the Protrusion of Migrating Cells A. Ponti, M. Machacek, S. L. Gupton, C. M. Waterman-Storer, G. Danuser
The leading edge of moving cells contains a population of actin molecules involved with membraneprotrusion and retraction and another that powers the cell’s movement.
1786 PLANT SCIENCE: Zooming In on a Quantitative Trait for Tomato Yield Using Interspecific Introgressions E. Fridman, F. Carrari, Y.-S. Liu, A. R. Fernie, D. Zamir
The sweetness of ketchup tomatoes is partly determined by a single point mutation in the enzyme thatgenerates glucose and fructose.
SCIENCE (ISSN 0036-8075) is published weekly on Friday, except the last week in December, by the American Association for the Advancement of
Science, 1200 New York Avenue, NW,Washington, DC 20005. Periodicals Mail postage (publication No. 484460) paid at Washington, DC, and addition-al mailing offices. Copyright © 2004 by the American Association for the Advancement of Science.The title SCIENCE is a registered trademark of the AAAS.Domestic individual membership and subscription (51 issues): $130 ($74 allocated to subscription). Domestic institutional subscription (51 issues): $500;Foreign postage extra: Mexico, Caribbean (surface mail) $55; other countries (air assist delivery) $85. First class, airmail, student, and emeritus rates on re-quest. Canadian rates with GST available upon request, GST #1254 88122. Publications Mail Agreement Number 1069624. Printed in the U.S.A.
Change of address: allow 4 weeks, giving old and new addresses and 8-digit account number. Postmaster: Send change of address to Science, P.O. Box 1811, Danbury, CT 06813–1811. Single copy sales: $10.00per issue prepaid includes surface postage; bulk rates on request. Authorization to photocopy material for internal or personal use under circumstances not falling within the fair use provisions of the CopyrightAct is granted by AAAS to libraries and other users registered with the Copyright Clearance Center (CCC) Transactional Reporting Service, provided that $15.00 per article is paid directly to CCC, 222 RosewoodDrive, Danvers, MA 01923. The identification code for Science is 0036-8075/83 $15.00. Science is indexed in the Reader’s Guide to Periodical Literature and in several specialized indexes.
Contents continued
REPORTS CONTINUED
1720&1779
1671www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004
sciencenow www.sciencenow.org DAILY NEWS COVERAGE
Exoplanet Says Cheese
If confirmed, new sighting would be first of a planet outside our solar system.
To Sleep, But Not to Dream
Stroke victim helps researchers locate brain’s dream center.
A Supernova’s Jet Set
Most detailed image of a star’s death exposes double jet of expelled matter.
science’s next wave www.nextwave.org CAREER RESOURCES FOR YOUNG SCIENTISTS
MISCINET: Aspirations of a Singing Doctor E. FranciscoCosmo Fraser’s first love was math, but this extraordinary scientist now takes care of patients, teaching,and music.
MISCINET: Starting Graduate School—Mathematics Training, Part 2 C. Castillo-Chavez Read more advice to students interested in math about that critical first year of graduate studies.
GLOBAL/CANADA: Navigating by the Numbers A. FazekasA University of Calgary expert tells how software plays a key role in interpreting global positioningdata and is used to integrate, manipulate, and display a wide range of information.
UK: A Transferable Skills Toolkit for Postdocs P. DeePhil Dee unveils the hidden transferable skills that postdocs, by default, have acquired.
UK: Dead-End in Academia—Redundancy with No Lectureship Ahead M. O’NeillNow 12 years on in academia, Mary O’Neill faces redundancy from her postdoc position and wonderswhat happened to her once brilliant science career.
NETHERLANDS: Europe Chooses “World Leaders of the Future” H. ObbinkHanne Obbink talks to one of the Dutch winners of the European Young Investigators Awards [in Dutch].
science’s sage ke www.sageke.org SCIENCE OF AGING KNOWLEDGE ENVIRONMENT
PERSPECTIVE: A Century of Population Aging in Germany E. Hoffmann and S. MenningHow old is Germany?
NEWS FOCUS: Tarnished Vision R. J. DavenportIron glut clouds eyes in mice.
NEWS FOCUS: Fatal Distraction M. BeckmanDisciplining misshapen proteins leaves cells vulnerable to oxidative stress and death.
science’s stke www.stke.org SIGNAL TRANSDUCTION KNOWLEDGE ENVIRONMENT
PERSPECTIVE: Emerging Role for ERK as a Key Regulator of Neuronal Apoptosis E. C. C. Cheungand R. S. Slack
Kinases better known for regulating growth and survival turn deadly in a model of neuronal cell death.
PERSPECTIVE: Mitochondrial Stop and Go—Signals That Regulate Organelle Movement I. J. Reynolds and G. L. Rintoul
Does NGF signal a mitochondrial docking station on the “microtubule railroad”?
Moving mitochondria in axons.
Germany’s aging populace.
Cosmo Fraser combines science, teaching,and music.
GrantsNetwww.grantsnet.org
RESEARCH FUNDING DATABASE
AIDSciencewww.aidscience.com
HIV PREVENTION & VACCINE RESEARCH
Functional Genomicswww.sciencegenomics.orgNEWS, RESEARCH, RESOURCES
Members Only!www.AAASMember.org
AAAS ONLINE COMMUNITY
www.scienceonline.org
Separate individual or institutional subscriptions to these products may be required for full-text access.
Add a little real-time to your cycler.Add a little real-time to your cycler.
R E A L - T I M E S Y S T E M
The Polymerase Chain Reaction (PCR) is a process covered by US Patents #4,683,195 and #4,683,202, which are ownedby Hoffmann-La Roche. Users should obtain a license to perform the reaction, and a license is currently availablethrough either Roche Molecular Systems of Pleasanton, California, or Applied Biosystems of Foster City, California.
Chromo4 is a trademark, and DNA Engine, MJ Research and the helix logo are registered trademarks in the US,belonging to MJ Research, Incorporated.
Specifications and appearance are subject to change without notice.
© 2004 MJ Research, Incorporated.
Innovative Chromo4 photonics shuttle. MJ Research packsall the optical components for real-time into a module that’s smallenough to fit in your hand. The Chromo4 photonics shuttle snapsinto a Chromo4 detector, and it scans a standard-sized, 96-wellvessel in about ten seconds. LEDs and photodiodes independentlyexcite and detect fluorescence from each well, yielding highsensitivity with minimal crosstalk.
MJ Research presents a new modular real-time detector that can befit to existing DNA Engine® bases. The Chromo4 system combinesthe precision of our thermal cyclers with a compact, solid-state,four-color detector, creating an innovative system specificallydesigned to address the dynamic needs of laboratories.
� Flexible detector fits all DNA Engine base units—no tools required.
� Interchangeable photonics shuttle, the heart ofthe detector, can be customized for unique chemistries.
� Sensitive, high-resolution multiplexing is possiblewith up to four colors of detection and excitation.
� Thermal-gradient capability allows optimizationof reactions.
� Compact system is one of thesmallest real-time systems available.
(888) 729-2164 • [email protected] • www.mjr.com/info/0144
Sugar in Two Steps Hexose sugars are naturally abundant, but it is often useful tomodify their structures for chemical and biochemical studies.Standard synthetic routes tend to be long and tedious and requiremultiple protection steps. Northrup and MacMillan (p. 1752,published online 12 August 2004) now describe a reaction se-quence for generating the sugars from achiral aldehyde precursorsin just two steps, thereby offering a convenient means of preparingdiverse structural variants. Inthe first step, α-oxyaldehydesare dimerized with L-proline asthe only source of asymmetrythroughout the sequence.In the second step, an aldoladdition-cyclization step iscontrolled by variation of sol-vent and Lewis acid to affordany of three stereoisomericproducts (glucose, mannose,or allose), all in high yield andstereochemical purity.
Disilyne DebutDouble and triple bonds arecommon in compounds of thefirst-row elements carbon,nitrogen, and oxygen. In con-trast, the heavier main groupcongeners tend to form single-bonded networks instead,because repulsion by inner-shell electrons keeps theatoms too far apart for π-bonding. Sekiguchi et al. (p. 1755; see the Perspective by West)have managed to push two Si atoms close enough together to forma Si-Si triple bond. They reduced a brominated precursor in whichthe Si atoms bear very bulky side groups that help destabilize moreconventional bonding options. X-ray crystallography revealed abent geometry consistent with theoretical predictions that the silicon orbitals do not hybridize like those of carbon do in rigidly linear alkynes.
Damage-Free DatingMany geologic boundaries reflect dramatic changes in speciesabundances or mark the origination of species. Thus, the accurate determination of their ages is essential for definingthe pace of evolution. One of the best dating methods, basedon the decay of U isotopes to Pb can be problematic if damaged parts of zircons, the primary uranium-bearing mineral,lose radiogenic Pb or incorporate older cores. Mundil et al.(p. 1760; see the News story by Kerr) used a recent methodthat strips out these damaged areas to refine the age of theend-Permian extinction and Permo-Triassic boundary. Their data on a sequence of ashes in two localities place the extinc-tion at 252.6 million years ago, about 1 million years older thanpreviously determined. The results support the conclusion thatthe extinction occurred within the limit of the method, just afew hundred thousand years.
Early Oxygen HistoryMeasurements of the three stable isotopes of oxygen in primitivemeteorites that formed in the solar nebula indicate that the nebulargas had an initial enrichment in 16O that was quickly depleted.Observations of molecular clouds indicate that ultraviolet radiationselectively dissociates C17O and C18O, but not C16O, which leavesthe atomic oxygen gas in the interior of the cloud depleted in 16O.Yurimoto and Kuramoto (p. 1763; see the Perspective by Yin)
have developed a model to explain the meteoritical data using the astronomicalobservations. The oxygen isotopic differ-ences developed in the molecular cloud viaphotodissociation. When the cloud collapsed into the solar nebula disk, the
isotopic differences were transported to the inner disk byicy dust grains that evaporatedwhen they neared the Sun.
Why the Ice?The large, permanent icesheets that presently occupyAntarctica began to formaround 14 million years ago,when Earth entered a phase of
global cooling. However, the climateprocesses that produced these changes, aswell as the temporal relation between icesheet growth and cooling, have remained obscure. Shevenell et al . (p. 1766) analyzed Mg/Ca ratios (a proxy for temperature), oxygen isotopes (whichrecord a combination of temperature and
seawater oxygen isotopic composition), and carbon isotopes (aproxy for atmospheric CO2 concentrations) of benthic foraminiferafrom Southern Hemisphere marine sediments with ages between15 and 13.2 million years. Deep-ocean cooling began roughly60,000 years before ice sheet growth, and both of these processes happened during a period of atmospheric CO2 increase. These findings suggest that factors other than radiative forcing, such asocean heat transport, were key elements of this climate transition.
Two Membranes, Two Fusion Mechanisms Mitochondria, the powerhouses of the cell, are surrounded by adouble membrane. Within the cell, mitochondria continually fuse
with one another, but themechanism by which theirtwo membranes can faith-fully fuse remains obscure.Meeusen et al. (p. 1747,published online 5 August2004; see the Perspectiveby Pfanner et al.) nowpresent a cell-free assaythat reconstitutes efficientmitochondrial fusion in
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1673
Standing CO2 on Its EndUnderstanding how plants reduce CO2 to sugars,and facilitating attempts to mimic this chemistry,requires better in-sight into the spe-cific binding geom-etry of CO 2 atmetal centers. Syn-thetic chemistsstudying the prob-lem usually startwith metal com-plexes that coordi-nate CO2 throughthe C atom, withone or both O atoms bent away from the metal.Castro-Rodriguez et al. (p. 1757) have prepared aU complex in which coordinated CO2 remains lin-ear and binds end-on to the metal through a singleO atom. X-ray crystallography verified this unusualbonding geometry.
edited by Stella Hurtley and Phil Szuromi
THIS WEEK INC
RED
ITS:
(TO
P TO
BO
TTO
M)
CA
STRO
–RO
DRI
GU
EZ E
T A
L.;M
EEU
SEN
ET
AL.
CONTINUED ON PAGE 1675
Information About
Applied Biosystems PCR Licensing Program
At Applied Biosystems we are proud of our role
in developing PCR technology. From the start,
as the exclusive licensee of PCR for research
and other non-diagnostic applications, we have
provided scientists with innovative tools for PCR
and access to the technology.
The Nobel Prize winning PCR process is
covered by patents in many countries through-
out the world. Because PCR is patented, using
PCR, even for research, requires a license. In
keeping with our philosophy of maximizing
scientists’ access to PCR, Applied Biosystems
makes licenses available in a number of ways.
To make it easy for users to obtain the PCR
rights they need, we not only offer PCR rights
in a variety of ways directly to end users, we
also have licensed many of our competitors
to convey these rights with their products.
Obtaining a license to perform automated
PCR for your own research is easy. You can
obtain the license automatically by using a
licensed DNA polymerase (available from over
25 manufacturers) with an Authorized thermal
cycler (available from a number of thermal
cycler suppliers). Alternatively, if you choose
not to use products from Applied Biosystems
or other licensed manufacturers, you need to
purchase the appropriate PCR research rights
directly from Applied Biosystems.*
Applied Biosystems also offers licenses for
other uses of PCR (for example, for providing
services) in a variety of fields, either directly
through license agreements or through products
from Applied Biosystems and licensed competitors
which convey these rights. In addition to research,
these fields include agricultural testing, animal
identity testing, environmental testing, food
testing, forensics and human identity testing,
and quality control testing.
For more detailed information on how to
obtain a license to practice the PCR process,
please visit our website at:
www.appliedbiosystems.com/ab/pcrlicensefaq
Or contact us at: Applied Biosystems,
Licensing Department, 850 Lincoln Centre Drive,
Foster City, CA 94404 USA, fax: 650.638.6071,
phone: 650.638.5845.
*Please note that, in addition to the PCR process rights, you may need other patent rights associated either with instruments or reagents.
Our goal is to continue developing PCR and maximizing its availability to users around the world.
1675www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004
vitro. In the assay, the fusion of the outer and inner mitochondrial membranes can be individually scrutinized, and the two fusion events can be mechanistically distinguished.
Lasting Legacy of Formative YearsDevelopment and disease susceptibility are not purely a function of genotype—environment plays a large part in shaping an organism and in its demise. Furthermore,the environment begins having its effect at the earliest of stages of development,during periconception, fetal, and infant stages. The concept of developmental origins ofdisease has gained credence through epidemiological and clinical studies. Gluckmanand Hanson (p. 1733) review fundamental observations, discuss mechanisms of action,and discuss the concept of developmental origins of disease from an evolutionary perspective. Finch and Crimmins (p. 1736) suggest that exposure to infection and oth-er environmental sources of inflammation during infancy and childhood leave a long-lasting imprint on morbidity and life expectancy in old age.
Eosinophil Effects in Mouse Models of Asthma An assortment of leukocyte subsets are recruited to the lung during an asthmaticepisode and accompany immediate changes to the mucosal lining, as well aslong-term airway remodeling. Eosinophils are dominant among these infiltratingcells, but their presence has, sofar, been linked only indirectlywith disease (see the Perspectiveby Wills-Karp and Karp). Lee etal. (p. 1773) used a mouse modelin which cell l ineage–specificdeletion of eosinophils could beachieved. In these animals, chal-lenge with an allergen normallyable to elicit a robust asthma-like response failed to generatesignificant pulmonary dysfunc-tion or mucus accumulation. In adifferent eosinophil-deficientmouse line generated by Humbles et al. (p. 1776), these acute aspects were notsignificantly affected, but over the long term, these mice were protected fromperibronchiolar collagen deposition and increases in airway smooth-muscle mass.
Dissecting the Evolution of a Sign LanguageHuman languages are digital in the sense that they are formed from discrete units.Is the brain predisposed toward dealing with sounds, words, and phrases, or are theexisting languages that we learn simply structured discretely? Senghas et al.(p. 1779; see the Perspective by Siegal) offer evidence in support of the formerview, drawing upon a population of deaf individuals in Nicaragua who have devel-oped a new sign language. Descriptions of complex motion events are segmentedinto separate gestures representing the manner of movement (such as rolling) aswell as path (such as downward).
How Sweet Is Your Tomato?Quantitative traits suggest an underlying complexity of metabolism because gradations of a particular phenotypic trait make themselves apparent. The sweetnessof tomatoes, particularly those tomatoes used for making ketchup, is one such trait.Fridman et al. (p. 1786) now analyze near-isogenic lines to identify the particular pointmutation in an invertase enzyme that is responsible for gradations of sweetness intomatoes. Unlike many other quantitative traits, which are often the summed result ofseveral mutations, this sweetness gene acts on its own.
KAMIYA BIOMEDICALCOMPANY
12779 Gateway Drive, Seattle, WA 98168(206) 575-8068 FAX:(206) 575-8094
www.kamiyabiomedical.com
Focusing on High-Quality Innovative Biologicals Since 1983
KAMIYA BIOMEDICAL
Research Assay Kits
Rat Visceral PreadipocyteCulture Kit
A revolutionary new culture system for studying the mech-anism of adipogenesis as well as for screening drugs that prevent metabolic syndrome diseases.Contains rat preadipocyte cells isolated from rat mesentery.Specialized differentiation medium contains no synthetic compounds or visceral adipo-genesis inhibitors.Medium contains only lipids as a promoter of visceral adipo-genesis.
Obesity / Diabetes ResearchAdiponectin ELISAGPDH AssayInsulin ELISAs for dog, mouse,
pig, and ratIntracellular Lipid QuantitationLeptin ELISALeptin Receptor ELISAMouse Microalbumin ELISARat Microalbumin ELISAMouse & rat Microalbumin
assays for chemistry analyzersResistin ELISAMouse Resistin ELISA
Infl ammationHigh-sensitive ELISAs for CRP
level in blood of mouse, rat,rabbit, pig, or dog
Mouse and rat IgE ELISAsDog CRP assay for chemistry
analyzersMouse & rat Haptoglobin ELISAs
Lipid ResearchCETP Activity Assay for serum
of mouse, rat, rabbit, horse, hu-man, and other mammals
CETP Drug Screening KitOxidized LDL ELISA
Bone ResearchHuman COMP ELISAMouse and rat COMP ELISAMouse and rat Osteopontin
ELISAsMouse and rat osteoclast
culture kits with mammoth tusk dentin slices
New
New
New
New
New
New
New
New
New
New
New
New
New
CONTINUED FROM 1673 THIS WEEK INC
RED
IT:L
EE E
T A
L.
BIBLIOGRAPHY
CENTRAL
Your High-Tech Commandand Control Center for References.
IntroducingReferenceManager11—apowerful upgrade to the
bibliographic software that streamlines research,writing andpublishing.
ReferenceManagerhas servedcorporate,governmentandacademicresearchers worldwide forover 20 years.Andnow version11delivers newways to shareand view your referencecollections:Post your databases to theWeb.Collaborate with colleaguesoveranetwork.Link to full text pdf files.
Theseare just someof thepowerful features thatawait you.
ReferenceManager is your commandand control center forall thingsreference related.
What’s new in v11:• PublishReferenceManagerdatabases to theWebor intranet• Create subjectbibliographies instantly• Accessnewand updated content filesat www.refman.com•Share traveling libraries with colleagues•Connect todata visualization tools
Put innovation intoaction.Order or upgrade today.Available forWindows in a single-user and network edition.Phone:800-722-1227 • 760-438-5526 • [email protected]
©Copyright 2004Thomson.ReferenceManager is a registered trademark ofThomson.All other trademarks are the property of their respective companies.
Download a Free Demo Todaywww.refman.com
EDITORIAL
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1677
The week-long visit of Science’s Richard Stone to North Korea (p. 1696) provides a fascinat-ing new take on this strange land. He was shown allegedly cloned rabbits (interesting iftrue), just a few months after U.S. nuclear scientist Sig Hecker was handed a glass jar supposedly containing homemade plutonium (frightening if true). All this comes amid frus-trating, sporadic six-party talks about North Korean nuclear and missile activities and thecollapse of the Framework Agreement of 1994: the deal that supposedly froze their
nuclear program in return for fuel oil and reactor construction. More ominously, it now appears that NorthKorea has a secret uranium enrichment program, and U.S. intelligence estimates that they may have re-cently reprocessed spent fuel into enough plutonium to make as many as six nuclear bombs.
North Korea has some 22 million people. About a quarter of these receive international food assis-tance, and refugees risk flight to an unwelcoming China. North Korea also maintains a million-man army,pursues major nuclear and missile programs, and threatens Seoul with entrenched conventionalweapons. Yet this troublesome pariah nation reportedly has a scientific and technical com-munity of 1.9 million people—poorly equipped but knowledgeable and congenial, Stonefound, and eager to begin scientific exchanges with the United States and Europe. Thiswould be a clear change in policy. During Secretary of State Madeleine Albright’s vis-it to Korea in late 2000, the United States reportedly proposed exchanges (notnecessarily scientific), but the idea was rejected by the Koreans.
There will be different U.S. reactions to this new prospect for engage-ment. Those who respond to countries that disagree with us by seeking toisolate them will call it a ploy to steal U.S. technology and will reject it out-right. Another group will embrace it, hoping to begin constructive discussionswith at least some people from this hyper-xenophobic country. A third group willwant to use it as leverage to gain concessions; if those are not forthcoming, theywill drop the idea. (Although scientific cooperation can often be a diplomaticsweetener, it rarely offers much leverage for securing major concessions.)
Everyone is a prisoner of his personal history. I went through the Cold Waras an inveterate engager, as the first U.S. scientific attaché in Eastern Europein the late 1960s, where I interacted with scientists that were more on our side thanthat of their own governments. Later I helped create the first U.S.-USSR Joint Committee onScience and Technology Cooperation, one element of the Nixon-Brezhnev detente agreed on at their 1972summit meeting; and I was also involved in the first, mutually cautious science exchanges with the Chi-nese, ending 22-plus years of no contacts at all. Repressive governments characteristically try to preventtheir people from having contacts with Americans, but those contacts are to our advantage because thecontagion of freedom and democracy is dangerous for totalitarian societies, not the other way around.
Such an engagement strategy is what Joseph Nye, the dean of Harvard’s Kennedy School, calls theuse of “soft power.” U.S. scientists took political risks in reaching out to Soviet physicist AndreiSakharov and his colleagues in post-McCarthy America, and they generated enough mutual trust to influence the positions of both governments. That eventually led to a series of arms control agreementsand helped both countries survive the U.S.-Soviet nuclear standoff in the era of mutual assured de-struction. George Kennan, America’s most prescient diplomat in the post–World War II period, createdthe Cold War containment strategy used against the USSR. But he argued for an engagement strategywith the Russian people and later lamented the heavy U.S. emphasis on containment in military termsand the relative neglect of available economic, political, psychological, and cultural tools.
These days, approaches employing soft power to build scientific and cultural bridges are often derided. But soft power may be even more important than before in a multipolar world in which terror-ism and rogue states present different challenges to democratic institutions. Scientific and technical cooperation can be an effective instrument for wielding that power. So if the North Koreans are serious,if they want to begin modest scientific exchanges on peaceful uses of science, I would jump at the opportunity—in a cautious and constructive way. The world needs soft power, and more of it. In NorthKorea and elsewhere, these are the weapons that must ultimately prevail.
Norman P. NeureiterNorman P. Neureiter is director of the AAAS Center for Science, Technology, and Security Policy in Washington, DC.
Talking with North Korea
CRE
DIT
:R.S
TON
E/SC
IEN
CE
The PCR process and 5' nuclease process are covered by patents owned by Roche Molecular Systems, Inc. and F. Hoffmann-La Roche Ltd. Practice of the patented polymerase chain reaction (PCR) process requires a license.The Applied Biosystems 7300/7500 Real-Time PCR Systems are Authorized Thermal Cyclers for PCR and may be used with PCR licenses available from Applied Biosystems. Their use with Authorized Reagents also provides a limitedPCR license in accordance with the label rights accompanying such reagents. Applied Biosystems is a registered trademark and AB (Design), Applera, Assays-on-Demand, iScience, and iScience (Design) are trademarks of AppleraCorporation or its subsidiaries in the US and/or certain other countries. TaqMan is a registered trademark of Roche Molecular Systems, Inc. Information is subject to change without notice. For Research Use Only. Not for use in diagnosticprocedures. ©2004 Applied Biosystems. All rights reserved.
iScience. Applied Biosystems provides the innovative
products, services, and knowledge resources that are
enabling new, integrated approaches to scientific discovery.
Real affordable.Real performance.Real easy.
A new generation of systems from the leader in real-time PCR.Now there are two new choices for advanced, multicolor real-time PCR. Both systems give you the gold standard
combination of TaqMan® assays and Applied Biosystems proven performance, plus unbeatable real-time chemistry
choices. The 7300 system combines high-end results with exceptional budget sensitivity. The 7500 system gives you
even more, including enhanced dye flexibility and powerful gene expression analysis software. Either way, it’s real easy,
with all-new software, TaqMan® assay products, and a comprehensive selection of reagents and consumables. For
the real deal in real-time PCR, visit http://info.appliedbiosystems.com/realtimepcr
Choices
from
the
lead
er in
real
-tim
e PCR!
NEW!
Applied Biosystems 7300 Real-Time PCR System Applied Biosystems 7500 Real-Time PCR System
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1679
E C O L O G Y / E V O L U T I O N
Swifter, Higher,StrongerSexual selection, the evolu-tionary corollary of matechoice, is generally studied inorganisms where direct mat-ings (for example, internalfertilization) between individ-uals take place. The variancein male mating success thatresults when females choose,
in particular, can lead to theevolution of showy andsometimes bizarre signals ofmale quality. However, theancestral condition for sexualreproduction in animals isbroadcast spawning and ex-ternal fertilization—that is,the release of sperm and eggsby benthic marine organismsinto the water column. Doessexual selection operate un-der these conditions?
In an experimental study ofreproduction in sea urchins,
Levitan finds that sexual se-lection—as identified by thedifference between malesand females in the variancefor fertilization success—does indeed occur, but onlyat intermediate populationdensities of males and fe-males. At low and high densi-ties, the variance in fertiliza-tion success did not differbetween the sexes, becauseof sperm limitation at low
density and spermcompetition at highdensity. Hence, sexualselection in seaurchins is under con-trol of the adult onlyin the sense of timingand quantity of ga-mete release; the restis mediated by traitsof the gametes them-selves. — AMS
Am. Nat. 164, 298 (2004).
M AT E R I A L S S C I E N C E
Fast-Flowing Filters
Porous membranes are usedextensively for separationprocesses such as water pu-rification. A current challengeis to fabricate membranematerials that can separateobjects differing in size byonly a few nanometers(which means small pores)and can still operate at a rea-
sonable filtration rate (smallpores are prone to blockage).
Akthakul et al. have en-hanced the filtration capabili-ties of a commercialpoly(vinylidene fluoride)(PVDF) membrane by spincoating a thin film of acopolymer consisting of aPVDF backbone, with shortpolyethylene oxide (PEO) sidechains grafted on via amethacrylate linkage. ThePEO and PVDF segments donot like to mix with eachother, so the chains segregatelocally into partially crys-talline PVDF regions separat-ed by PEO nanochannels.Water is repelled by thePVDF but is able to movethrough the PEO regions, thusenhancing the overall trans-port through the commercialPVDF membrane. The PEOsegments interact stronglywith the water molecules,which prevents organics fromclinging and fouling themembrane. The membranescan also be used for molecu-lar sieving, as demonstratedby the separation of similarlycharged dye molecules, andfor size-exclusion chromatog-raphy, as demonstrated bythe separation of vitamins B2 and B12. — MSL
Macromolecules 10.1021/ma048837s(2004).
B I O C H E M I S T RY
One Size Fits Many
Enzymatic reactions generallydemand a precise positioningof catalytic residues; thus,structural disorder in a proteinmight be expected to be in-consistent with catalyticprowess. However, Vamcava etal. show that a monomericchorismate mutase (mCM),obtained by redesign of thenaturally occurring dimer, dis-plays many of the characteris-tics of a molten globule yetstill possesses one-third of thewild-type catalytic efficiency.Spectroscopic and thermal de-naturation experiments allsuggest that the monomericform has high conformationalflexibility and only adopts anordered structure when a tran-sition-state analog (inhibitor)is added. In contrast, dimericCM is ordered both in the ab-sence and presence of ligand.The polar character of the ac-tive site in the interior ofmCM, unlike the hydrophobiccore of the wild-type enzyme,fails to rigidify the foldedstate. When the inhibitorbinds, it fills the pocket andsupplies interactions thatpropagate and improve globalordering, as in the induced fit
EDITORS’ CHOICEH I G H L I G H T S O F T H E R E C E N T L I T E R A T U R E
edited by Gilbert Chin
Spawning sea urchin.
CRE
DIT
S:(T
OP)
MC
GO
VER
N E
T A
L.,J
.GEO
PHYS
.RES
.10
9,1
0.10
29/2
004J
E002
258
(200
4);(
BOTT
OM
) PH
ILLI
PC
OLL
A,
OC
EAN
LIG
HT.
CO
M
CONTINUED ON PAGE 1681
P L A N E TA RY S C I E N C E
Paradise Lost?
The dry and barren landscape on Mars is often compared to dry and desolatedeserts on Earth, but McGovern et al. have chosen a tropical paradise, theHawaiian islands, for a terrestrial analogy to explain the evolution of OlympusMons, which is the largest known volcano (about 23 km in height and 600 kmin diameter) in the solar system. It is partly bounded by an irregular scarp ashigh as 10 km, and lobes of hummocky terrain, which are called aureole de-posits, funnel outward from this scarp. The aureole deposits contain remnantsof formerly continuous volcanic flow units and morphologically resemble land-slides around the edges of Hawaiian volcanoes.The authors suggest that, in sim-ilar fashion, Olympus Mons may have grown and spread by basal detachmentfaults. In Hawaii, the landslides are lubricated by high pore fluid pressure on thefaults and are mostly submarine, which poses the question:Was Olympus Monsonce a fluid paradise, too? — LR
J. Geophys. Res. 109, 10.1029/2004JE002258 (2004).
Morphologies of the Nuuanu slide off Oahu(left) scaled in horizontal dimension to the au-reole deposits of Olympus Mons (right).
Generating Top Quality PCR Results isYour Primary Goal...
SIGMA-ALDRICH CORPORATION • BOX 14508 • ST. LOUIS • MISSOURI 63178 • USA
L E A D E R S H I P I N L I F E S C I E N C E , H I G H T E C H N O L O G Y A N D S E R V I C Esigma-aldrich.com
Enhancing Performance in Your PCR Reaction isSigma’s Primary Focus!
Learn more about Sigma’s PCR productsand special offers at sigma-aldrich.com/pcr2
PCR technologies are continuously
evolving and so are your reagent
needs. Committed to supporting
the diverse needs of your research,
Sigma provides a broad range of high
quality PCR reagents. From standard
PCR reactions to Quantitative PCR
technology, Sigma has the products
you need & the support you deserve.
One Source for All Your PCR Needs!
PCR – Standard, Hot Start, Long & Accurate, and Specialty Enzymes
RT-PCR – Enzymes and KitsQuantitative PCR – Reagents for Dual-labeled Probes & DNA Binding Dyes
Custom Capabilities – Blends, dNTPs, Buffers & Reagents
Custom Oligos & Arrays – Expression Profiling, Products & Services
PCR Accessories – Plates, Tubes, Tips & More
model of enzyme catalysis, in which thecatalytically active conformation is lockedinto place as the reaction progresses. Theidea that folding and catalysis can belinked implies that modern-day enzymescould have evolved from molten globules.Perhaps, a primordial structural plasticityconferred relaxed substrate specificity en-abling a limited set of protein enzymes tocatalyze a wide range of reactions. — VV
Proc. Natl. Acad. Sci. U.S.A. 101, 12860 (2004).
M I C R O B I O L O G Y
Thermophilic Parasite
Malaria is responsible for the death ofmore than 1 million people each year. Inthe course of cycling between the mosqui-to vector and the human host, the malarialparasite Plasmodium falciparum is exposedto high temperatures, up to 41°C in febrilepatients, which are sufficient to send themicrobe into heat shock.
Pavithra et al. examined the role ofheat shock proteins in the developmentof the parasite within infected redblood cells by periodically incubatingthem at elevated temperatures,mimicking the recurrent febrileepisodes typical of malarial infec-tions. They find that elevated tem-peratures promote parasite developmentwithin the erythrocyte and that an in-hibitor of one of the heat shock proteinsactually disrupted parasite development.These findings support the idea that theparasite exploits the environmental cuesprovided by elevated body temperature tostage its development during infection, and
it suggests that interventions that affectthe malarial heat shock response may beuseful in combating the disease. — SMH
J. Biol. Chem. 10.1074/jbc.M409165200 (2004).
C H E M I S T RY
Rare Frameworks
Many transition metals have been shownto form solid-state compounds with inter-penetrating frameworks, which are of in-terest as they can provide routes to creat-ing microporous materials. However, forthe lanthanides and actinides, progresshas been slower, with the only known ex-ample being an actinide compound, thethiophosphate UP4S12.
Aitken and Kanatzidis report that thereaction of ytterbium in a potassium thio-phosphate flux yields K6Yb3(PS4)5. X-raycrystallography revealed two interlockednetworks with three types of Yb3+ centers
linking the PS4 tetra-hedra, one with theexpected bicapped
trigonal prismaticgeometry and the oth-
er two with a distortedoctahedral structure. The
small size of Yb relative to
other lanthanides appears to be the keyfactor in allowing it to adopt the octahe-dral geometry needed to form this type ofnetwork. — PDS
J. Am. Chem. Soc. 10.1021/ja0474648 (2004).
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 20041681
Genomics 3:
ADVERTISER DIRECTORY
Turn to page 1793
Drug Discovery andBiotechnology Trends
The following organizationshave placed ads in theSpecial Advertising Section
ADVERTISER Page
Dharmacon, Inc. ............. 1795
Quantum DotCorporation ........................ 1799
SANYO Sales& MarketingCorporation/SANYO ElectricBiomedical Co., Ltd. ... 1797
SuperArrayBioscienceCorporation ........................ 1800
Takara Bio Inc. ................. 1792
It’s a Knockdown!
CONTINUED FROM 1679 EDITORS’ CHOICE
Moving TRPs to the Membrane
Singh et al.report that cation channels of the transient recep-tor potential (TRP) family are dynamically inserted into the
plasma membrane in response to ligand stimulation of G protein–coupled recep-tors, as recently found after stimulation of receptor tyrosine kinases. The authorsidentified proteins involved in exocytosis—vesicle-associated membrane protein 2(VAMP2) and α soluble N-ethylmaleimide–sensitive factor attachment protein(αSNAP) as interacting partners for the N-terminal domain of TRPC3 in a yeasttwo-hybrid screen. The interaction with proteins involved in exocytosis was con-firmed with heterologously expressed proteins in transfected cells and endoge-nously expressed protein in rat brain. Exposure of human embryonic kidney cellsexpressing TRPC3 to the GPCR ligand carbachol resulted in increased abundance ofTRPC3 at the cell surface, and this insertion was inhibited by cleavage of VAMP2with tetanus toxin. Measurements of calcium influx with fluorescent indicatorsverified that the channels were functional. Thus, regulated insertion appears tocontribute to agonist-stimulated TRP activity and calcium signaling. — NG
Mol. Cell 15, 635 (2004).
H I G H L I G H T E D I N S C I E N C E ’ S S I G N A L T R A N S D U C T I O N K N O W L E D G E E N V I R O N M E N T
The interpenetrating lattices in red/orangeand blue/light blue; K+ in green.
CRE
DIT
:AIT
KEN
AN
D K
AN
ATZ
IDIS
,J.A
M.C
HEM
.SO
C.
10.1
021/
JA04
7464
8 (2
004)
HELPING RE-BUAROUND T
NEW NAME NEW DEADLINESAME GREAT PRIZE!
The Amersham Biosciences, now partof GE Healthcare, and Science Prizefor Young Scientists has changed itsname to the Young Scientist Award.
ILD IMMUNITYHE WORLD
YOUR OPPORTUNITY TO WIN IS NOWThe Young Scientist Award was established in 1995 and
is presented by Science/AAAS and GE Healthcare(formerly Amersham Biosciences). The aim of the prizehas been to recognize outstanding Ph.D. graduatestudents from around the world and reward theirresearch in the field of molecular biology.
This is your chance to gain international acclaim and
recognition for yourself and your school. If you completedyour Ph.D. in molecular biology* during 2003, describeyour work in a 1,000-word essay. Then enter it forthe 2004 Young Scientist Award. Your essay will bereviewed by a panel of distinguished scientists, who'llselect one grand prize winner and up to seven otherwinners. The grand prize winner will get his or her essaypublished in Science, receive US$25,000, and win atrip to the awards ceremony in Washington, D.C. The
closing date for entries is October 8, 2004.
Go to www.aaas.org/youngscientistaward tofind the entry form and award rules. We wishcontinued success to Dr. Cascalho. And to you.
Read Dr. Cascalho's latest findings in J of Immunol.
172:4709-4716 2004.
Immunological memory efficiently protects us from dying from
infections caused by bacteria or viruses. However, some microbeschange so fast that memory is never achieved and diseases caused bysuch agents are resistant to traditional vaccination, presenting a seriouschallenge for medical science worldwide. Dr. Marilia Cascalho isworking on ways to overcome the limitations of vaccination, creating
immunity even to viruses that can change.
Effective vaccination requires immune competency. Thus individualsthat are immuno-deficient cannot effectively be vaccinated againstinfectious diseases. Dr. Cascalho together with her collaborators at the
Mayo Clinic, Drs. Platt and Ogle, discovered a mechanism forrebuilding immunity in people with reduced T cell diversity, which will
be valuable in treating patients with HIV and following transplanta-
tion or chemotherapy.
Dr. Cascalho became a regional winner of the 1999 Prize for Young
Scientists with an essay on the discovery that DNA repair contributesto mutations in the immunoglobulin genes that are central to the
development of immunological memory and effective vaccination. She
believes the prize has played an important part in her subsequentprogress. "And it shows that revolutionary contributions to science can
be recognized even at an early stage in your career."
Established and presented by:
* For the purpose of this prize, molecular biology is defined as “that part of biology which attempts to interpret biological events in terms of the physico-chemical properties of molecules in a cell”
(McGraw-Hill Dictionary of Scientific and Technical Terms, 4th Edition).
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1684
John I. Brauman, Chair, Stanford Univ.Richard Losick, Harvard Univ.Robert May, Univ. of OxfordMarcia McNutt, Monterey Bay Aquarium Research Inst.Linda Partridge, Univ. College London Vera C. Rubin, Carnegie Institution of WashingtonChristopher R. Somerville, Carnegie Institution
R. McNeill Alexander, Leeds Univ.Richard Amasino, Univ. of Wisconsin, MadisonCornelia I. Bargmann, Univ. of California, SFBrenda Bass, Univ. of UtahRay H. Baughman, Univ. of Texas, Dallas Stephen J. Benkovic, Pennsylvania St. Univ.Michael J. Bevan, Univ. of Washington Ton Bisseling, Wageningen Univ.Lewis M. Branscomb, Harvard Univ.Dennis Bray, Univ. of Cambridge Stephen Buratowski, Harvard Medical SchoolJoseph A. Burns, Cornell Univ.William P. Butz, Population Reference Bureau Doreen Cantrell, Univ. of Dundee Vicky Chandler, Univ. of ArizonaMildred Cho, Stanford Univ.David Clapham, Children’s Hospital, Boston David Clary, Oxford University J. M. Claverie, CNRS, Marseille Jonathan D. Cohen, Princeton Univ.Robert Colwell, Univ. of Connecticut Peter Crane, Royal Botanic Gardens, Kew
F. Fleming Crim, Univ. of Wisconsin William Cumberland, UCLAJudy DeLoache, Univ. of VirginiaRobert Desimone, NIMH, NIH John Diffley, Cancer Research UK Dennis Discher, Univ. of Pennsylvania Julian Downward, Cancer Research UK Denis Duboule, Univ. of Geneva Christopher Dye, WHORichard Ellis, Cal Tech Gerhard Ertl, Fritz-Haber-Institut, Berlin Douglas H. Erwin, Smithsonian Institution Barry Everitt, Univ. of Cambridge Paul G. Falkowski, Rutgers Univ.Tom Fenchel, Univ. of Copenhagen Barbara Finlayson-Pitts, Univ. of California, Irvine Jeffrey S. Flier, Harvard Medical School Chris D. Frith, Univ. College London R. Gadagkar, Indian Inst. of Science Mary E. Galvin, Univ. of Delaware Don Ganem, Univ. of California, SF John Gearhart, Johns Hopkins Univ.Dennis L. Hartmann, Univ. of Washington Chris Hawkesworth, Univ. of BristolMartin Heimann, Max Planck Inst., Jena Evelyn L. Hu, Univ. of California, SB Meyer B. Jackson, Univ. of Wisconsin Med. School Stephen Jackson, Univ. of Cambridge Bernhard Keimer, Max Planck Inst., Stuttgart Alan B. Krueger, Princeton Univ.Antonio Lanzavecchia, Inst. of Res. in Biomedicine Anthony J. Leggett, Univ. of Illinois, Urbana-Champaign Michael J. Lenardo, NIAID, NIH Norman L. Letvin, Beth Israel Deaconess Medical Center
Michael S. Levine, Univ. of California, Berkeley Richard Losick, Harvard Univ.Andrew P. MacKenzie, Univ. of St. Andrews Raul Madariaga, École Normale Supérieure, Paris Rick Maizels, Univ. of Edinburgh Eve Marder, Brandeis Univ.George M. Martin, Univ. of Washington Edvard Moser, Norwegian Univ. of Science and TechnologyElizabeth G. Nabel, NHLBI, NIH Naoto Nagaosa, Univ. of Tokyo Alexandra Navrotsky, Univ. of California, Davis James Nelson, Stanford Univ. School of Med.Roeland Nolte, Univ. of Nijmegen Malcolm Parker, Imperial CollegeLinda Partridge, Univ. College London John Pendry, Imperial College Josef Perner, Univ. of SalzburgPhilippe Poulin, CNRSJoanne Richards, Baylor College of MedicineTrevor Robbins, Univ. of Cambridge Janet Rossant, Univ. of Toronto Edward M. Rubin, Lawrence Berkeley National LabsDavid G. Russell, Cornell Univ.Peter St. George Hyslop, Toronto Philippe Sansonetti, Institut Pasteur Dan Schrag, Harvard Univ.Georg Schulz, Albert-Ludwigs-Universität Paul Schulze-Lefert, Max Planck Inst., Cologne Terrence J. Sejnowski, The Salk Institute George Somero, Stanford Univ.Christopher R. Somerville, Carnegie InstitutionJoan Steitz, Yale Univ.Will J. Stewart, Blakesley, UK Edward I. Stiefel, Princeton Univ.
Thomas Stocker, Univ. of Bern Tomoyuki Takahashi, Univ. of Tokyo Marc Tessier-Lavigne, Genentech Craig B. Thompson, Univ. of PennsylvaniaJoan S. Valentine, Univ. of California, LA Michiel van der Klis, Astronomical Inst. of Amsterdam Derek van der Kooy, Univ. of Toronto Bert Vogelstein, Johns Hopkins Christopher A. Walsh, Harvard Medical School Christopher T. Walsh, Harvard Medical School Graham Warren, Yale Univ. School of Med.Julia R. Weertman, Northwestern Univ.Daniel M. Wegner, Harvard UniversityEllen D. Williams, Univ. of Maryland R. Sanders Williams, Duke University Ian A. Wilson, The Scripps Res. Inst.Jerry Workman, Stowers Inst. for Medical ResearchJohn R. Yates III,The Scripps Res. Inst.Richard A. Young, The Whitehead Inst.Martin Zatz, NIMH, NIH Walter Zieglgänsberger, Max Planck Inst., Munich Huda Zoghbi, Baylor College of Medicine Maria Zuber, MIT
David Bloom, Harvard Univ.Londa Schiebinger, Stanford Univ.Richard Shweder, Univ. of ChicagoRobert Solow, MITDavid Voss, ScienceEd Wasserman, DuPontLewis Wolpert, Univ. College, London
EDITOR-IN-CHIEF Donald KennedyEXECUTIVE EDITOR Monica M. Bradford
DEPUTY EDITORS NEWS EDITOR
R. Brooks Hanson, Katrina L. Kelner Colin Norman
EDITORIAL SUPERVISORY SENIOR EDITORS Barbara Jasny, Phillip D. Szuromi;SENIOR EDITOR/PERSPECTIVES Orla Smith; SENIOR EDITORS Gilbert J. Chin,Pamela J. Hines, Paula A. Kiberstis (Boston), Beverly A. Purnell, L.Bryan Ray, Guy Riddihough (Manila), Linda R. Rowan; ASSOCIATE
EDITORS Lisa D. Chong, Marc S. Lavine, H. Jesse Smith, Valda Vinson,Jake S.Yeston; ONLINE EDITOR Stewart Wills; ASSOCIATE ONLINE EDITOR TaraS. Marathe; BOOK REVIEW EDITOR Sherman J. Suter; ASSOCIATE LETTERS EDI-
TOR Etta Kavanagh; INFORMATION SPECIALIST Janet Kegg; EDITORIAL MANAG-
ER Cara Tate; SENIOR COPY EDITORS Jeffrey E. Cook, Harry Jach, BarbaraP. Ordway; COPY EDITORS Cynthia Howe, Sabrah M. n’haRaven,Jennifer Sills, Trista Wagoner; EDITORIAL COORDINATORS Carolyn Kyle,Beverly Shields; PUBLICATION ASSISTANTS Chris Filiatreau, Joi S. Granger,Jeffrey Hearn, Yolanda Matthews, Scott Miller, Jerry Richardson,Tunisia L. Riley, Brian White,Anita Wynn; EDITORIAL ASSISTANTS E.AnnieHall, Lisa Johnson, Patricia M. Moore, Ramatoulaye Diop; EXECUTIVE
ASSISTANT Sylvia S. Kihara; ADMINISTRATIVE SUPPORT Patricia F. Fisher
NEWS SENIOR CORRESPONDENTS Eliot Marshall, Jean Marx; DEPUTY NEWS
EDITORS Robert Coontz, Jeffrey Mervis, Leslie Roberts, RichardStone, John Travis; CONTRIBUTING EDITORS Elizabeth Culotta, PollyShulman; NEWS WRITERS Yudhijit Bhattacharjee, Jennifer Couzin,
Constance Holden, Jocelyn Kaiser, Richard A. Kerr, Andrew Lawler(Boston), David Malakoff, Gregory Miller, Elizabeth Pennisi,Charles Seife, Robert F. Service (Pacific NW), Erik Stokstad; DavidGrimm (intern); CONTRIBUTING CORRESPONDENTS Marcia Barinaga(Berkeley, CA), Kathryn Brown, Barry A. Cipra, Adrian Cho, JonCohen (San Diego, CA), Daniel Ferber, Ann Gibbons, Robert Irion,Mitch Leslie (NetWatch), Charles C. Mann, Evelyn Strauss, GaryTaubes, David Voss, Ingrid Wickelgren; COPY EDITORS Linda B. Felaco,Daniel T. Helgerman; ADMINISTRATIVE SUPPORT Scherraine Mack, FannieGroom BUREAUS: Berkeley, CA: 510-652-0302, FAX 510-652-1867,Boston, MA: 617-542-5098, San Diego, CA: 760-942-3252, FAX760-942-4979, Pacific Northwest: 503-963-1940
PRODUCTION DIRECTOR James Landry; SENIOR MANAGER Wendy K. Shank;ASSISTANT MANAGER Rebecca Doshi; SENIOR SPECIALISTs Vicki J. Jorgensen,Jessica K. Moshell,Amanda K. SkeltonPREFLIGHT DIRECTOR David M. Tompkins; MANAGER Marcus SpieglerART DIRECTOR Joshua Moglia; ASSOCIATE ART DIRECTOR Kelly Buckheit;ILLUSTRATOR Katharine Sutliff; SENIOR ART ASSOCIATES Laura Creveling,HollyBishop, Preston Huey, Julie White; ASSOCIATE Nayomi Kevitiyagala;PHOTO RESEARCHER Leslie Blizard
SCIENCE INTERNATIONAL
EUROPE ([email protected]) EDITORIAL: INTERNATIONAL MANAGING
EDITOR Andrew M. Sugden; SENIOR EDITOR/PERSPECTIVES Julia Fahrenkamp-Uppenbrink; SENIOR EDITORS Caroline Ash, Stella M. Hurtley, Ian S.Osborne, Peter Stern; ASSOCIATE EDITOR Stephen J. Simpson; EDITORIAL SUP-
PORT Cheryl Sharp, Emma Westgate; ADMINISTRATIVE SUPPORT JanetClements, Phil Marlow, Jill White; DEPUTY NEWS EDITOR Daniel Clery;CORRESPONDENTGretchen Vogel (Berlin:+49 (0) 30 2809 3902,FAX +49(0) 30 2809 8365); CONTRIBUTING CORRESPONDENTS Michael Balter (Paris),Martin Enserink (Amsterdam and Paris); INTERN Fiona Proffitt
ASIA Japan Office:Asca Corporation, Eiko Ishioka, Fusako Tamura, 1-8-13, Hirano-cho, Chuo-ku, Osaka-shi, Osaka, 541-0046 Japan; +81 (0)6 6202 6272, FAX +81 (0) 6 6202 6271; [email protected] JAPAN NEWS
BUREAU: Dennis Normile (contributing correspondent, +81 (0) 3 33910630,FAX 81 (0) 3 5936 3531;[email protected]); CHINA REPRESENTATIVE
Hao Xin, + 86 (0) 10 6307 4439 or 6307 3676, FAX +86 (0) 10 63074358; [email protected]; SOUTH ASIA Pallava Bagla (contributing cor-respondent +91 (0) 11 2271 2896; [email protected])
EXECUTIVE PUBLISHER Alan I. LeshnerPUBLISHER Beth Rosner
FULFILLMENT & MEMBERSHIP SERVICES ([email protected])DIRECTOR Marlene Zendell; FULFILLMENT SYSTEMS: MANAGER WaylonButler; MEMBER SERVICES: MANAGER Michael Lung; SENIOR SPECIALIST PatButler; SPECIALIST Laurie Baker; REPRESENTATIVE Karina Smith; MARKETING
ASSOCIATE Deborah Stromberg
BUSINESS OPERATIONS AND ADMINISTRATION DIRECTOR DeborahRivera-Wienhold; BUSINESS MANAGER Randy Yi; SENIOR FINANCIAL
ANALYSTS Lisa Donovan, Jason Hendricks; ANALYST Jessica Tierney;RIGHTS AND PERMISSIONS: ASSOCIATE Emilie David; MARKETING: DIRECTOR SITE
LICENSE SALES Tom Ryan; SENIOR SALES REPRESENTATIVE Mehan Dossani;DIRECTOR OF INTERNATIONAL MARKETING AND RECRUITMENT ADVERTISING
Deborah Harris; INTERNATIONAL MARKETING MANAGER Wendy Sturley;MARKETING/MEMBER SERVICES EXECUTIVE: Linda Rusk; JAPAN SALES AND
MARKETING MANAGER Jason Hannaford; MARKETING: DIRECTOR JohnMeyers; MEMBERSHIP MARKETING MANAGER Darryl Walter; MARKETING
ASSOCIATES Karen Nedbal, Julianne Wielga; RECRUITMENT MARKETING
MANAGER Allison Pritchard; ASSOCIATES Mary Ellen Crowley, AmandaDonathen, Catherine Featherston; ELECTRONIC MEDIA: INTERNET
PRODUCTION MANAGER Lizabeth Harman; ASSISTANT PRODUCTION
MANAGER Wendy Stengel; SENIOR PRODUCTION ASSOCIATES Sheila Myers,Lisa Stanford; PRODUCTION ASSOCIATE Carla Cathey; LEAD APPLICATIONS
DEVELOPER Carl Saffell; ADMINISTRATIVE SUPPORT Catherine Holland
PRODUCT ADVERTISING ([email protected]); MIDWEST RickBongiovanni: 330-405-7080, FAX 330-405-7081• WEST COAST/W. CAN-
ADA B. Neil Boylan (Associate Director): 650-964-2266, FAX 650-964-2267 • EAST COAST/E. CANADA Christopher Breslin: 443-512-0330,FAX 443-512-0331 • UK/SCANDINAVIA/FRANCE/ITALY/BELGIUM/NETHERLANDS
Andrew Davies (Associate Director): +44 (0)1782 750111, FAX +44(0) 1782 751999 • GERMANY/SWITZERLAND/AUSTRIA Tracey Peers(Associate Director): +44 (0) 1782 752530, FAX +44 (0) 1782752531 JAPAN Mashy Yoshikawa: +81 (0) 33235 5961, FAX +81 (0)33235 5852 ISRAEL Jessica Nachlas +9723 5449123 • TRAFFIC MANAGER
Carol Maddox; SALES COORDINATOR Deiandra Simms
CLASSIFIED ADVERTISING ([email protected]); U.S.: SALES
DIRECTOR Gabrielle Boguslawski: 718-491-1607, FAX 202-289-6742; INTERNET SALES MANAGER Beth Dwyer: 202-326-6534; INSIDE
SALES MANAGER Daryl Anderson: 202-326-6543; WEST COAST/MIDWEST
Kristine von Zedlitz: 415-956-2531; EAST COAST Jill Steinberg:914-834-8733; LINE AD SALES Emnet Tesfaye: 202-326-6740; SENIOR
SALES COORDINATOR Erika Bryant; SALES COORDINATORS RohanEdmonson, Caroline Gallina, Joyce Scott, Shirley Young;INTERNATIONAL: SALES MANAGER Tracy Holmes: +44 (0) 1223 326525,FAX +44 (0) 1223 326532; SALES Emilie Stott; SALES ASSISTANT ClaireGriffiths; JAPAN: Jason Hannaford: +81 (0) 52 777 9777, FAX +81(0) 52 777 9781; PRODUCTION MANAGER Jennifer Rankin; ASSISTANT
PRODUCTION MANAGER Deborah Tompkins; ASSOCIATES Christine Hall,Amy Hardcastle; SENIOR PUBLICATIONS ASSISTANT Robert Buck
AAAS BOARD OF DIRECTORS RETIRING PRESIDENT, CHAIR Mary EllenAvery; PRESIDENT Shirley Ann Jackson; PRESIDENT-ELECT Gilbert S.Omenn; TREASURER David E. Shaw; CHIEF EXECUTIVE OFFICER Alan I.Leshner; BOARD Rosina M. Bierbaum; John E. Burris; John E.Dowling; Karen A. Holbrook; Richard A. Meserve; Norine E.Noonan; Peter J. Stang; Kathryn D. Sullivan; Lydia Villa-Komaroff
www.sciencemag.org
1200 New York Avenue, NW Washington, DC 20005
Editorial: 202-326-6550, FAX 202-289-7562News: 202-326-6500, FAX 202-371-9227
Bateman House, 82-88 Hills RoadCambridge, UK CB2 1LQ
+44 (0) 1223 326500, FAX +44 (0) 1223 326501
SUBSCRIPTION SERVICES For change of address, missing issues,new orders and renewals, and payment questions: 800-731-4939 or 202-326-6417, FAX 202-842-1065. Mailing addresses:AAAS, P.O. Box 1811, Danbury, CT 06813 or AAAS MemberServices, 1200 New York Avenue, NW, Washington, DC 20005
REPRINTS Ordering/Billing/Status 800-635-7171; Corrections202-326-6501
PERMISSIONS 202-326-7074, FAX 202-682-0816
MEMBER BENEFITS Bookstore: AAAS/Barnes&Noble.com bookstorewww.aaas.org/bn; Car purchase discount: Subaru VIP Program202-326-6417; Credit Card: MBNA 800-847-7378; Car Rentals:Hertz 800-654-2200 CDP#343457, Dollar 800-800-4000#AA1115;AAAS Travels: Betchart Expeditions 800-252-4910; LifeInsurance: Seabury & Smith 800-424-9883; Other Benefits:AAASMember Services 202-326-6417 or www.aaasmember.org.
[email protected] (for general editorial queries)[email protected] (for queries about letters)[email protected] (for returning manuscript reviews)[email protected] (for book review queries)
Published by the American Association for the Advancement ofScience (AAAS), Science serves its readers as a forum for the pres-entation and discussion of important issues related to theadvancement of science, including the presentation of minority orconflicting points of view, rather than by publishing only materialon which a consensus has been reached. Accordingly, all articlespublished in Science—including editorials, news and comment,and book reviews—are signed and reflect the individual views ofthe authors and not official points of view adopted by the AAASor the institutions with which the authors are affiliated.
AAAS was founded in 1848 and incorporated in 1874. Its mis-sion is to advance science and innovation throughout the worldfor the benefit of all people. The goals of the association are to:foster communication among scientists, engineers and thepublic; enhance international cooperation in science and itsapplications; promote the responsible conduct and use of sci-ence and technology; foster education in science and technol-ogy for everyone; enhance the science and technology work-force and infrastructure; increase public understanding andappreciation of science and technology; and strengthen sup-port for the science and technology enterprise.
INFORMATION FOR CONTRIBUTORS
See pages 102 and 103 of the 2 January 2004 issue or accesswww.sciencemag.org/feature/contribinfo/home.shtml
SENIOR EDITORIAL BOARD
BOARD OF REVIEWING EDITORS
BOOK REVIEW BOARD
High-Performance Dialysis
G r a s p t h e P r o t e o m e ™
Tel: 815-968-0747 or 800-874-3723 • Fax: 815-968-7316 Customer Assistance E-mail: [email protected]
Outside the United States, visit our web site or call 815-968-0747 to locate your local Perbio Science branch office (below) or distributor
© Pierce Biotechnology, Inc., 2004. Pierce products are supplied for laboratory or manufacturing applications only.Slide-A-Lyzer ® is a registered trademark of Pierce Biotechnology, Inc. *Slide-A-Lyzer ® Dialysis Cassette Technology is protected by U.S. patent # 5,503,741 and other patent pending.
Belgium & Dist.:Tel +32 (0)53 83 44 [email protected]
France:Tel 0800 50 82 [email protected]
Germany:Tel 0228 [email protected]
The Netherlands: Tel 076 50 31 [email protected]
United Kingdom: Tel 0800 [email protected]
Switzerland: Tel 0800 56 31 [email protected]
The new 30 ml (working range12-30 ml) Slide-A-Lyzer ® DialysisCassette* was built for dialysis ina BIG way. It comes with its owninternal buoy.
The color-coded transparentframes of the Slide-A-Lyzer ®
Cassette Family allow you toinstantly know the molecularweight cut-off of the membraneand view the placement of yourneedle during sample injection.
To view demos, see a completelist of products or to downloadan instruction booklet, visitwww.piercenet.com/dialysis.
BIG. Buoy.Our line keeps getting BIGger and better.
Highlights:• The 30 ml cassette has the
buoy built into its frame• >95% sample recovery• No knots, caps, lids or clamps
to loosen, fall off, open or leak• A rigid frame that permits
smooth and complete withdrawal of samples
• Color-coded frames indicate membrane MWCO
FREE picture frame offer!Buy any package of Slide-A-Lyzer®
Dialysis Cassettes before 12/15/04,and receive a free magnetic picture frame that looks just like our Cassettes! Void where prohibited.Limit one frame per order.
www.piercenet.com
GenePix Autoloader 4200AL microarray scanner with automatic slide handling
Walk away from the scanner and use your time more productively.
Automatically loads and scans and analyzes up to 36 slides.
Top-quality data. Line-by-line dynamic autofocus
ensures unprecedented field uniformity.
The scanner that won’t limit your science. Complete
flexibility to configure scanning and analysis parame-
ters for one slide or many,
all alike or each different. Use any slides you like—wet
or dry, with low- or high-density arrays*. Choose up to
four lasers and 16 emission filters. Upgrade now or later
from the GenePix Professional 4200A.
Simple and reliable. Store and scan slides in a single easy-to-load magazine.
Our unique ‘never let go’ design ensures zero breakage.
Powerful analysis tools. Available with GenePix Pro microarray image analysis
and Acuity® enterprise microarray informatics
software—the choice of leading microarray laboratories.
Visit our website now. Discover more about the freedom of
GenePix automation. www.axon.com
Finallythe freedom you need to make discoveries faster.
ANNOUNCING
*GenePix and Acuity systems are compatible with all 25x75 mm slide arrays from Agilent,Amersham, Illumina, Schleicher & Scheull, Combimatrix, lab-printed slides, and most othersources.
®
Gen
ePix
is a
regi
ster
ed trad
emar
k of
Axo
n In
stru
men
ts. A
ll ot
her t
rade
mar
ks a
re o
wne
d by
thei
rre
spec
tive
owne
rs.
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1687
I M A G E S
Not of This WorldThere may not be life elsewhere in the solar system, but there isgeology, such as Mars’s 24-kilometer-tall volcano Olympus
Mons and our moon’s SouthPole–Aitken basin, a vast crater.Map-a-Planet from the U.S.Geological Survey lets youchart the surface features ofseven solar system bodies,including Mars, Venus, and fourof Jupiter’s satellites. You candownload maps based on a variety of measurements. Forinstance,Venus aficionados canchoose among seven data sets,such as radar and microwaveemissions, captured by the
Magellan probe. The Galileo spacecraft snapped the pock-markedsurface (above) of Jupiter’s giant moon Ganymede, which is larger than Mercury.
pdsmaps.wr.usgs.gov
D ATA B A S E
Federal Science RegisterCould methanol fuel cells power an artificial heart?How did dark lizards adapt to the bleached background
at White Sands in New Mexico?These are just two of the studies the U.S. government underwrites. This site from theDepartment of Energy offersone-stop searching of federallyfunded research. You can prowlsynopses of more than 500,000current and recently completedprojects sponsored by sixagencies, including DOE, theNational Science Foundation,the National Institutes ofHealth, and the EnvironmentalProtection Agency.
www.osti.gov/fedrnd
I M A G E S
Killers in the ForestThe fungus Discula destructivabesmirched this creamy dogwoodbloom (right) and can eventuallyslay the tree. The parasite, whichis devastating dogwoods in theEast and West, is just one of thenon-native organisms gnawing,sucking, and sliming their way
through U.S. forests. The new Gallery of Pestsfrom The Nature Conservancy (TNC) briefly describes more than 30 insects, fungi, and other trou-blemakers. Many accounts include photos of the organisms and thedamage they inflict, along with maps that illustrate their spread. Thegallery is the latest addition to TNC’s invasive species site, which includes a host of resources aimed at land managers. To learn moreabout pesky invasive plants, for instance, consult Australian expert Rod Randall’s Big Weed List.
tncweeds.ucdavis.edu/index.html
D ATA B A S E
Parsing RNAResearchers looking for broad patterns in the sequence or structure ofRNA may want to check out Transterm, a tool from the University ofOtago in New Zealand.The site lets users analyze RNAs from organ-isms whose gene sequences are housed in GenBank. For example, vis-itors can select a species and then determine how often its RNAs useeach of the three-letter codons that designate a specific amino acid.The site also ferrets out motifs: nucleotide sequences or structuralquirks that can affect the RNA’s stability and how the cell reads it.
uther.otago.ac.nz/v5g.html
NETWATCHedited by Mitch Leslie
E D U C AT I O N
Limulus in the LimelightThe American horseshoe crab (Limulus polyphemus, below) is a lab-oratory star. Its blue blood clumps in response to certain microbes,inspiring today’s standard test for identifying bacterial contamina-tion. Studies of the crab’scompound eyes led to NobelPrize–winning research onthe neurophysiology of vi-sion. To learn more aboutthese creatures, which areactually closer kin to spidersthan to true crabs, visitthese sites.
A basic primer from theUniversity of Delaware* probessubjects such as the crab’sevolution—the earliest fossil isabout 500 million years old—and natural history. Everyspring, for instance, drovesof horseshoe crabs scuttleashore along the Atlantic and Gulf coasts to mate and lay eggs. Asimilar site from the Delaware-based Ecological Research and Development Group† highlights details of the crab’s anatomy anddevelopment. It also supplies a hefty bibliography of horseshoe crabliterature and features a gallery of art and photos. Both sites discussthreats to the crabs (Science, 21 May, p. 1113), such as beachfrontdevelopment.
* www.ocean.udel.edu/horseshoecrab† www.horseshoecrab.org
CRE
DIT
S (T
OP
TO B
OTT
OM
):FR
AN
S LA
NTI
NG
/WW
W.L
AN
TIN
G.C
OM
;RO
BERT
L.A
ND
ERSO
N/U
SDA
FO
REST
RY S
ERV
ICE;
USG
S
Send site suggestions to [email protected]. Archive: www.sciencemag.org/netwatch
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1688
CRE
DIT
:PH
OTO
BY
JO
HN
LA
NG
FORD
NEWSP A G E 1 6 9 2 1 6 9 3
When theArctic wassubtropical
Don’t lock uppathogengenomes
Th is We e k
For most scientists, having their research citedon the floor of the U.S. House of Representa-tives would be a crowning achievement. Butfor University of Missouri, Columbia, psy-chologist Laura King, it was part of a “reallyscary, bizarre day” that culminated in a voteto block her work and that of a second psy-chologist. It came minutes after the Houseimposed a cap on international travel to scien-tific meetings. While fiscal conservatives aretouting the events of 9 September as a victoryagainst government waste, sci-entific organizations are fum-ing about what they see as anunwarranted intrusion into thescientific process.
The setting for last week’slegislative fireworks was the2005 budget for the NationalInstitutes of Health (NIH) andits parent body, the Depart-ment of Health and HumanServices (HHS). Last yearHouse Republicans narrowlymissed pulling the plug onseveral NIH studies on sexualbehavior on the grounds thatthe work was inappropriateand a waste of money. Anamendment to block funds forthe projects failed by just twovotes. This year, however, anamendment by RepresentativeRandy Neugebauer (R–TX) tobar HHS from using 2005funds for two psychologygrants passed on a voice vote.The immediate victims wereKing’s work on college students’ perceptionsof themselves and a study by Samuel Goslingof the University of Texas, Austin, on howstudents’ choice of dorm room décor can re-flect their personality and mental health.
The vote would not impact funding for thetwo grants, which has already been disbursed.And the prohibition could be altered ordropped when the bill is reconciled with onepassed by the Senate, which has not yet acted.But scientific groups are alarmed by theprecedent. “There’s no question that Congresshas an oversight function here, but we don’t
think that extends to making decisions aboutindividual grants,” says David Moore, head ofgovernmental relations for the Association ofAmerican Medical Colleges. NIH DirectorElias Zerhouni says, “We need to do every-thing possible to preserve our historically suc-cessful system of independent peer review.”
King’s momentous day began with aphone call from the office of her congress-man, Representative Kenny Hulshof(R–MO). Armed with a quick e-mail from
King, Hulshof defended King’s work andplaced her entire CV in the official record.But his arguments, along with those defend-ing Gosling, did not prevail. “It’s very dis-heartening,” King says. “Any grant in the so-cial sciences or behavioral sciences could beattacked on this same basis.” “I was dis-mayed,” says Gosling, adding that, like King,he believes House members lack the knowl-edge to assess the grants.
Neugebauer disagrees. “Taxpayer dollarsshould be focused on serious mental health is-sues like bipolar disorders and Alzheimer’s,”
he told his colleagues. He derided Gosling’sresearch as “interior decoration” andsummed up King’s work as asking studentsto define a “meaningful day,” which he said“the federal government has no businesspaying someone” to study.
Although the legislation doesn’t requireKing or Gosling to return any money, the twoinvestigators may not be out of the woods.King is planning to apply for funds to renewher grant, and because her grant number is in-cluded in the amendment, she may need tosubmit a completely new proposal to continueher work. This summer Gosling received a 3-year, $200,000 grant from the National Sci-ence Foundation (NSF). A spokesperson forNeugebauer says the congressman is weigh-ing whether to introduce a similar amend-ment when NSF’s spending bill, now mired incommittee, comes before the full House.
Scientific societies are urging the Senate toreject the Neugebauer amendment when theNIH bill comes before it. Federation of Ameri-can Societies for Experimental Biology presi-dent Paul Kincade also hopes that a pendingNIH plan to require grantees to provide a lay-language summary of the public-health im-portance of their grants will help prevent suchattacks in the future. “It’s important for scien-tists to explain what we do,” he says.
The House floor vote also approved an-other amendment exerting control over NIH.The proposal, from Representative ScottGarrett (R–NJ), orders HHS to send nomore than 50 staff members to any single in-ternational conference. Garrett objected tothe $3.6 million spent on the 2002 interna-tional AIDS meeting in Barcelona, to whichHHS sent 236 people. The money mighthave been better spent on buying drugs forAIDS patients, he says. HHS global healthchief William Steiger has recently an-nounced a similar goal of sending no morethan roughly 50 staffers to international con-ferences (Science, 10 September, p. 1552).
Strict enforcement of that limit—whichgenome institute director Francis Collins thisweek called “alarming”—could have a seri-ous impact on several upcoming conferences,an NIH official notes, including a human ge-netics meeting in Toronto and two Keystoneconferences on AIDS. The House and Senatecould revise the wording to give HHS somewiggle room, for example, by exemptingmeetings in Canada. “It certainly is fixable,” astaffer says. But in the meantime, for HHSscientists, foreign travel just got a little morecomplicated. –JOCELYN KAISER
House Votes to Kill Grants,Limit Travel to Meetings
M A N A G I N G S C I E N C E
Trivial pursuit? Psychologist Sam Gosling’s work on how personalitycan shape work and living spaces took a hit in the House.
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1689
CRE
DIT
S (T
OP)
:NA
SA/J
PL;(
BOTT
OM
,LEF
T TO
RIG
HT)
DA
N H
ERRI
CK
/ZU
MA
/CO
RBIS
;REU
TERS
/CO
RBIS
1 6 9 6 1 7 0 5 1 7 0 6North Koreaquietlyreaches out
Biosecurityaround theworld
Dating thegreatest massextinction
Foc u s
It was a gut-wrenching sight. As the cap-sule carrying precious samples of the solarwind collected by the Genesis spacecraftapproached its Utah landing site, NASATV viewers around the world could clearlysee the 1.5-meter-wide, discus-shaped cap-sule tumbling earthward with no sign of itsstabilizing parachute. Within seconds, thecapsule slammed into the desert floor,abruptly ending the $264million mission to return asample of the sun for studyof the solar system’s origins.
All is not lost for Genesis,however. “There is still hopefor science from this mis-sion,” says Genesis projectmanager Donald Sweetnamof the Jet Propulsion Labora-tory (JPL) in Pasadena, Cali-fornia. The 205-kilogram capsule weathered its 360-kilometer-per-hour return sur-prisingly well, although it em-bedded itself halfway into theground and cracked open.“We’re quite confident we canachieve a high degree of suc-cess from a science point of view,” says Genesis co-investigator Roger Wiens of Los AlamosNational Laboratory in New Mexico. “Keycollector materials have been determined tobe very intact,” says Donald Sevilla, Genesisrecovery lead engineer at JPL. Brittle samplecollectors did shatter, but pieces of collectormay suffice for analysis.
With desert dirt driven inside the capsuleand broken sample wafers falling out, “the major problem we have is contamina-tion,” says Sevilla. During its 3 years in space, Genesis had exposed various sorts of sample-collecting surfaces to the onrushingsolar wind of atomic particles. Back on Earth,researchers planned to extract the embeddedparticles and determine their elemental andisotopic composition, which would preciselyreflect the sun’s present composition and thusthe solar system’s starting composition. Thatwould help researchers understand everythingfrom the formation of the solar system to thesun’s acceleration of the solar wind. But thespacecraft’s precious cargo is embedded onlyabout 50 nanometers beneath the surface of
the collectors. So specialists at NASA’s John-son Space Center in Houston, Texas, willhave to not only put Humpty Dumpty backtogether again but also figure out how toclean collector sur-faces without re-moving the samples.
And technicianswon’t be the only
ones facing unexpected challenges. The dis-aster also aggravates NASA’s struggles withits Discovery program of low-cost missionsto the solar system (Science, 23 July, p. 467).
Discovery’s CONTOUR spacecraft blew upin 2002 on its way to a comet, and severalmissions in the works or recently launchedhave encountered cost overruns and devel-
opment problems. What, if anything,
NASA can do to shoreup management of on-going missions will de-pend on the nature ofthe Genesis failure. Al-though the probe wasn’tdesigned to send backdata while entering theatmosphere, the recov-ery crew quickly deter-
mined that none of the explosives that de-ploy the parachutes had gone off, suggestingthat the capsule’s computer had never sentthe command to fire. An onboard batterythat had been acting up during the flight fellunder immediate suspicion, but a mishap in-vestigation board will take the next fewmonths to determine a probable cause.
The Genesis disaster worries Peter Tsouof JPL, the deputy principal investigator ofthe Discovery program’s Stardust mission,launched in 1999. Tsou notes that Stardust’ssample-return capsule carrying comet dustwas designed and built by the same industrypartners as the Genesis capsule. “I’m keep-ing my fingers crossed” for the 2006 return,he says, but “frankly, there’s not much wecan do now.” –RICHARD A. KERR
Aiming for the Sun, Crashing to EarthS PA C E P R O G R A M
On 2 November, U.S. voters will decidewhether to give Republican PresidentGeorge W. Bush a second term or putDemocrat John Kerry in the WhiteHouse. Continuing a presidential elec-tion-year tradition, Science has askedeach candidate to lay out his views onmore than a dozen science-related is-sues facing the nation. Their answersand an accompanying editorial areavailable online (www.sciencemag.org/sciext/candidates2004). The candidates’comments will also appear in the 1 October issue of the magazine.
The Candidates Speak on ScienceS C I E N C E P O L I C Y
Down and dirty. Genesis PI Donald Burnett of Caltech sorts throughsome of the more heavily damaged solar-wind collectors (inset) fol-lowing last week’s crash landing of the sample-return capsule.
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004
CRE
DIT
:M.J
.DA
NIE
LS E
T A
L./S
CIE
NC
E
1691
NCI Backs Nano in Cancer WarNational Cancer Institute (NCI) officials thisweek announced plans to spend $144 mil-lion over 5 years on nanotechnology effortsto fight cancer (Science, 23 July, p. 461).About $90 million will be used to establishat least five new multi-university centers ofexcellence over the next year aimed at usingnanosized particles to create novel diagnos-tic, therapeutic, and imaging techniques.An-other $38 million will flow to individual in-vestigators and $16 million to trainingawards.
NCI has supported nano projects for thelast 6 years, and most of the initiative’sfunds will come from repackaging existingefforts and terminating current programs,says NCI deputy director Anna Barker. Still,the time is right for such an effort, sayschemist Richard Smalley of Rice Universityin Houston,Texas. Nanotechnology gives re-searchers a bevy of new approaches to tar-geting specific cells within the body, he says:“There is a brave new world out there for di-agnosis and treatment.” –ROBERT F. SERVICE
Panel Recommends KeepingGerman Cloning Ban, for NowGermany’s federal Bioethics Council has rec-ommended that the nation maintain itsmoratorium on all forms of cloning—fornow. But although the 25-member councillast week unanimously called for a world-wide ban on reproductive cloning, its mem-bers split on the question of allowing re-search cloning, which uses nuclear transferto develop stem cells from human embryos.
In the council’s 13 September state-ment, one group of five members rejectedall cloning research, calling it morally unjus-tified. A second group of 12 members saidthat research cloning should be allowed un-der strict rules. Five members said that re-search cloning should be prohibited for nowbut could be justified in the future if ad-vances make it more likely to produce treat-ments. Despite the apparent majority for al-lowing cloning research (Science, 20 August,p. 1091), the panel urged the government tomaintain its current moratorium.
Panel member and Nobel laureate Chris-tiane Nüsslein-Volhard of the Max PlanckInstitute for Developmental Biology inTübingen says she is pleased with the com-promise. Although she supports regulatedcloning research, she says current tech-niques are so inefficient in animal experi-ments that “it is premature” to move to hu-man cells. Science minister Edelgard Bul-mahn praised the report, saying she sees noreason to change Germany’s embryo-protection law. –GRETCHEN VOGEL
ScienceScope
Cells with mutations in BRCA2, a breastcancer susceptibility gene, display a widerange of chromosomal abnormalities—everything from simple breaks to the gainor loss of whole chromosomes. Re-searchers think that this genomic instabili-ty, apparently the result of the inactivationof BRCA2, helps generate additional muta-tions that drive cells to become cancerous.New findings, described by Ashok Venkitara-man and his colleagues at the University ofCambridge, U.K., and published online thisweek by Science (www.sciencemag.org/cgi/content/abstract/1102574), now point to anovel way in which BRCA2 inactivationmay lead to cells that have abnormal chro-mosome numbers, a condition known asaneuploidy.
This work suggests that the loss of BRCA2 function perturbs how dividingcells separate. If so, “that would be a newway to get [genomic] instability … and po-tentially interesting,” says cancer gene ex-pert Bert Vogelstein of Johns Hopkins Uni-
versity School of Medicine in Baltimore,Maryland.
Researchers, including Venkitaraman,had previously shown that the proteinmade by BRCA2 is needed to repair chro-mosome defects, particularly the breaks inthe DNA strands that can occur duringDNA replication. Yet a mystery remained.Defective DNA repair resulting from BRCA2 mutations “explains the abnormalchromosome structures [seen in cancercells] but doesn’t easily account for largechanges in chromosome numbers,” Venki-taraman says.
Work by others had hinted that BRCA2loss might also interfere with events duringmitosis. To test this further, the Cambridgeteam determined how long it takes normalcells and cells in which either one or bothcopies of BRCA2 was inactivated toprogress from the onset of chromosomeseparation to complete daughter-cell sepa-
ration. Cells with one inactive BRCA2copy took slightly longer than normal cellsto separate. That interval was muchlonger—it was more than double the timefor controls—for cells with two inactivecopies. Indeed, many of those cells didn’tseparate at all and ended up with two nuclei.
Still, a holdup in cytokinesis could havesimply been the indirect result of unre-paired DNA strand breaks. Dividing cellshave ways to check for damaged chromo-somes and can hold up mitosis until thedamage is repaired. But the Venkitaramanteam has other evidence that suggests tothem that BRCA2 plays a direct role in reg-ulating cytokinesis.
In particular, they found that its proteinlocalizes, along with proteins known to beinvolved in cytokinesis, in the central por-tion of the dividing cell and in the bridgethat connects the daughters as they pullapart. “It’s the first evidence to show that[BRCA2] is at the critical [cytokinesis] siterather than where we normally expect to see
it in the nucleus,” says breast cancer geneexpert Simon Powell of Harvard’s Massa-chusetts General Hospital. BRCA2 “not only has a role in repair, … but it has thisadditional role in cytokinesis,” he concludes.
Cytokinesis experts aren’t so sure, how-ever. Alexey Khodjakov of the New YorkState Department of Health’s WadsworthCenter in Albany says he is “not im-pressed” by the work, arguing that Venki-taraman’s team has little evidence beyondthe observed problems with cytokinesis inthe mutant cells. “They don’t have an ex-planation for how it happens,” he says.Given that, there’s still a possibility that thecytokinesis inhibition is the indirect resultof impaired DNA repair in the mutants.
Venkitaraman concedes that that is stilla possibility, but he says he and his col-leagues are currently working to defineBRCA2’s mechanism of action and hope toresolve the issue soon. –JEAN MARX
M E D I C I N E
Possible New Role for BRCA2
In the right place. As chromosomes (blue) separate during cytokinesis, BRCA2 and proteins such asaurora-B kinase that are known to be involved in this last stage of mitosis colocalize (yellow).
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1692
CRE
DIT
S (T
OP
TO B
OTT
OM
):C
DC
;SO
URC
E:H
ARV
ARD
UN
IVER
SITY
The possibility of bioterrorism shouldn’tstop scientists from freely sharing genomedata, concludes a new report from the Na-tional Academies’ National Research Coun-cil (NRC). The study, requested by the CIAand the National Science Foundation, saysthat limiting public access to genome dataon potential bioweapons is impractical andwould do more scientific harm than good.
The U.S. government typically requires allfederally funded scientists to make theirgenome data public. Since scientists se-quenced the first viral genome in 1975, theyhave released the genetic codes of more than1100 viruses and 150 bacteria, includingthose of the dangerous pathogens that causesmallpox, anthrax, and the plague. In thewake of the October 2001 U.S. anthrax at-tacks, however, some analysts have proposedrestricting access to such data to make sure itdoesn’t fall into the wrong hands. They wor-ried that would-be bioterrorists might drawupon the growing mountain of gene sequence
data in public databases toengineer new bioweapons,such as unusually infec-tious viruses or toxic bac-teria that resist drugs.
But “open access isessential if we are tomaintain the progressneeded to stay ahead ofthose who would attemptto cause harm,” saysStanley Falkow, a micro-biologist at Stanford University in Palo Alto,California, who led thenew study (www.nap.edu/catalog/11087.html). It isunlikely that raw sequencedata would help bioterror-ists develop superweapons, the NRC panelsays, and locking away information wouldharm efforts to improve biodefenses and fightemerging diseases such as severe acute respi-
ratory syndrome. Coming up with workablerestrictions would be difficult, the panel adds.The genomes of many dangerous pathogensare already in the public domain, and there islittle agreement on what kinds of information
should be put off-limits. Ifthe government needs tokeep genomic secrets, itsays, it should use itslong-standing authority toclassify information.
The panel’s approachsits well with several sci-entists concerned aboutbiosecurity. “This is theright decision, from thestandpoints of both publichealth and security,” saysBarbara Hatch Rosenberg,a bioweapons expert at theState University of NewYork’s Purchase College.“Stringent restrictionwould pose unacceptablecosts,” agrees molecular
biologist Richard Ebright of Rutgers Univer-sity in New Brunswick, New Jersey. “Thereare no ‘biohackers’ using genome data inbasements.” –DAVID MALAKOFF
Report Upholds Public Access to Genetic Codes
D ATA S E C U R I T Y
The percentage of women offered tenuredslots in Harvard University’s Faculty of Artsand Sciences (FAS) has shrunk by half in thepast 5 years. In a letter sent this summer toPresident Lawrence Summers and obtainedby Science, some two dozen women facultymembers called the dramatic drop an unin-tended result of policies put in place sinceSummers took office in 2001. Summers, inturn, blames departmental search commit-tees for not looking harder for strong womencandidates. Both sides agree, however, thatthe issue is worth talking about and have
scheduled a sit-down next month to figureout how Harvard can do better.
“The whole concern about increasing di-versity on campus has been downgraded,”says a senior faculty member who, like othersigners who spoke to Science, requestedanonymity. “We’d hate to go back to a 1980sworld at Harvard in which only 7% oftenured FAS faculty are women.”
Women are generally underrepresentedamong the faculty of major research universi-ties, and the situation becomes more pro-nounced as they ascend the professorial ranks.
In theory, Harvard is in a betterposition to correct a gender im-balance than most universities,because it rarely awards tenureto those already on campus.But the share of women offeredthose coveted slots hasslumped from 37% of the totalpool in 2000–01 to 16% in theacademic year that just ended(see graph). That’s below theoverall faculty ratio of 19.6%,posing a threat to hard-wongains during the 1990s.
On 18 June, 26 tenuredfaculty women laid out theirconcerns in a three-page letter
to Summers and FAS Dean William Kirby.They cited several possible contributing fac-tors, including the elimination of an affirma-tive action dean in 2001 and the university’semphasis on hiring “rising young stars,” anage cohort that one of the signers says “cor-responds to a woman’s child-bearing years.”
On 23 July, Summers and Kirby wroteback. The quest for younger faculty, said Sum-mers, should actually narrow the gender gap,because “the pool of women available in mostfields is larger in cohorts at an earlier careerstage.” Kirby explained that affirmative actionis a priority for four new division deans—po-sitions created since Summers arrived—andadded that new hiring policies will ensuremore “broad and thorough” searches.
Summers and the petitioners concur thatthe key to improving the situation lies withhow department chairs choose to fill theirtenured slots. But the signers say Summersneeds to lean more heavily on those chairs.“Most members of the search committee aremen,” says one petitioner, “and they’ll oftenbring in a token woman candidate afterthey’ve decided to hire somebody else.”
The two sides will discuss the matter at alunch on 6 October. “We’re hopeful aboutchange,” says a signer, “because Larry is smartand very educable.” –YUDHIJIT BHATTACHARJEE
Harvard Faculty Decry Widening Gender GapW O M E N I N S C I E N C E
Force for good. Academy panel wantsgenomes of potential bioweapons suchas anthrax to remain public.
0
5
10
15
20
25
30
35
40Tenure offers to women
34.1%37.1%
25.7%
18.8%15.8%P
erce
ntag
e
Year’99–’00 ’00–’01 ’01–’02 ’02–’03 ’03–’04
HARVARD
Wrong direction. Women faculty members say Harvard hastaken a step back in providing opportunities for women.
N E W S O F T H E W E E K
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004
CRE
DIT
:CA
NAT
EC A
SSO
CIA
TES
INTE
RNAT
ION
AL,
CA
LGA
RY
ScienceScope
1693
Japan Revises Mad Cow PlansJapan is scaling back its policy of testingall slaughtered cows for “mad cow dis-ease” (bovine spongiform encephalopa-thy, BSE). But its new plan to test onlyslaughtered cows older than 20 monthswill still be the world’s most stringentBSE screening program.
The new policy, set to begin later thismonth, was a compromise, says TakashiOnodera, a molecular biologist at theUniversity of Tokyo and a member of agovernment advisory group. Europe andthe United States test cows that are 30months and older, he notes, in part be-cause scientists believe younger cowshaven’t accumulated enough BSE-causingprions to be picked up by current tests.Japan’s Finance Ministry also wanted tocut back on “useless testing” to trim the$30 million to $40 million annual cost,but the Ministry of Health and consumergroups were reluctant to raise the cutoffage any higher because Japan has foundthe disease in 21- and 23-month-oldcows.
–DENNIS NORMILE
FDA Panel Approves ADHDStudyA controversial study that would exposehealthy children to a stimulant shouldproceed, a Food and Drug Administration(FDA) ethics panel recommended lastweek. The pediatric ethics subcommitteedecided that the study, on attentiondeficit hyperactivity disorder (ADHD), isethically acceptable. But it urged spon-sors to offer less compensation to en-rolled families, saying a proposed $570payment might unduly influence parentswho needed the money.
The ADHD study is funded by the Na-tional Institutes of Health and led bychild psychiatrist Judith Rapoport. Itraised red flags among reviewers becausescientists wanted to enroll both healthychildren and those with ADHD, all aged 9to 18 (Science, 20 August, p. 1088). Allsubjects would receive one dose of dex-troamphetamine, a drug used to treatADHD, and then undergo a magnetic res-onance imaging scan to see whether thebrains of healthy and ADHD children re-spond differently to the drug.
The subpanel’s recommendation nowgoes to the full pediatric advisory com-mittee, which will then make a formalrecommendation to FDA.
–JENNIFER COUZIN
Drillers returned to Tromsø, Norway, thisweek with sediment cores from the firstholes ever drilled into the deep, ice-coveredArctic Ocean. The cores contain evidence ofa dramatic defrosting of the Arctic Oceannear the North Pole 55 million years ago anda long, slow slide toward the perennial icecover of recent times. Somewhere in thehundreds of meters of mud cored should bea record of the last ice-free Arctic summersof millions of years ago, conditions that mayreturn in the greenhouse world of 2100.
The deep-drilling success of the $12.5 million Arctic Coring Expedition(ACEX) comes after decades of merely pick-ing at the upper few meters of Arctic sea-floor sediments. Since the 1960s, scientificocean drilling in other seas has returned 160kilometers of rockand sediment cores.But scientif ic drillships had to flee atthe sight of ice, and inthe Arctic only thetop few meters ofsediment could besampled through theoceanwide ice.
Now, under thenew Integrated OceanDrilling Program(Science, 18 April2003, p. 410), the 13-member EuropeanConsortium for Oc-ean Research Drillinghas fielded a three-ship flotilla: an ice-reinforced drill shipto float 1300 metersabove the drill holeplus two icebreak-ers—one of them nuclear-powered. Atthe drill sites, just 220 kilometers from theNorth Pole, ice as much as 4 meters thickcovered the surface, usually with only a fewsmall gaps. Despite a string of mechanicalbreakdowns—a crucial high-pressure pumpvalve broke three times—the ships wereequal to the task. “We found that even inheavy ice conditions, we could stay [over thesame hole] as long as 8 days,” says KateMoran of the University of Rhode Island,Narragansett, who with Jan Backman ofStockholm University in Sweden was anACEX co-chief scientist. “We can probablygo any place in the Arctic Ocean and drill.”
In 3 weeks of drilling operations, ACEXbored through all 410 meters of sediment atone site on the underwater Lomonosov Ridge
and drilled to shallower depths in five otherholes. All told, the 19 shipboard scientistsfrom eight nations gathered a total of 339 me-ters of sediment as old as 80 million years.
Their biggest find was a couple of hun-dred thousand years’ worth of sedimentfrom 55 million years ago. It contains ani-mal and plant microfossils typical of 20°Csubtropical waters, not the subzero waters oftoday. The fossils mark the so-called Paleo-cene-Eocene Thermal Maximum (PETM)recorded around the globe in marine sedi-ments of the time. “Getting the PETM was afabulous result,” says Moran. Seismic prob-ing of the site had suggested that sedimentsof PETM age were missing there.
Now, paleoceanographers can try tosort out the Arctic Ocean’s role in the
PETM. The warm-ing seems to havebeen triggered by amassive release ofmethane, a green-house gas, storedbeneath the sea flooras an icy hydrate(Science, 28 January2000, p. 576). It’s un-clear what drove themethane release, but ageochemical peculiar-ity of the ancient Arc-tic might have beeninvolved. ACEX sci-entists found striking-ly low Arctic seawatersalinities during mostof the past 60 millionyears, due partly tolarge influxes of riverwater. Such low-density waters mighthave altered oceancirculation globally if
they leaked into the Atlantic, Moran notes.Once global Eocene warmth began to
wane, the world was on its way toward thedeep chill of the past few million years. Thefirst sure signs of Arctic ice—bits of sand thatmust have rafted to mid-ocean in one-timegrounded ice—appeared in 40-million-year-old sediments. That’s earlier than some scien-tists had expected. Seven million years ago,the delivery of ice-borne sand picked upsharply, suggesting more and possibly year-round ice. But pinning down when Arcticsummers last saw ice-free waters—a condi-tion global warming might bring on by theend of the century—will require close inspec-tion of the cores on shore, says Moran. Shecan hardly wait. –RICHARD A. KERR
Signs of a Warm, Ice-Free ArcticPA L E O C E A N O G R A P H Y
Ice eaters. Icebreakers (bottom and middle) runinterference for the stationary drill ship (top).
Is your PCR fast enough?
A new tempo that defies speed limits – Rapidly evolving PCR technology meets its match with theMastercycler ep line of high-speed thermal cyclers.
The system Mastercycler ep is futuristic; they are thefastest instruments in their class. With heating rates ofup to 6 °C/s, the Mastercycler ep gradient S is the starof the show. For the first time in history an instrumentcan perform a “device-driven Hot Start” via Impulse™PCR technology.
The new system Mastercycler ep:� Extremely fast heating and cooling� Intuitive graphic programming� Time-saving, software supported implementation
in existing Mastercycler configurations� High flexibility: One Control Panel easily operates
up to 5 different thermomodules� Silent like a whisper
For more information, go to:www.eppendorf.com
Your local distributor: www.eppendorf.com/worldwide · Application Hotline: +49 180-3 66 67 89
Eppendorf AG · Germany · Phone: +49 40-53801-0 • Brinkmann Instruments, Inc. · USA · Phone: 800-645-3050
� Three differentblock formats
� Unique impulse PCRtechnology
� Perfect for GLP com-pliant environments
� Manual or motorized heatedlid with ESP technology
epp
end
orf®
is a
reg
iste
red
tra
dem
ark.
licensedfor
PCR
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1695
Data from company-sponsored clinical trialsare often treated as business secrets, but thatpractice may soon change. In the wake of al-legations that a few companies have sup-pressed negative results to promote theirdrugs, some members of Congress say theyintend to make it easier for the public totrack clinical studies. Democrats plan to in-troduce legislation in both the House andSenate this month to create a mandatorypublic registry. It would require that all clini-cal studies be described publicly at their in-ception and that results be added when a tri-al is complete.
The proposal is part of a surge in effortsto overhaul the rules of clinical reporting.Last week, an international consortium of 13medical journals announced that it wouldpublish results only from clinical trials thatwere publicly regis-tered when the trialbegan. Hurrying tohead off legislation,the PharmaceuticalResearch and Manu-facturers of America(PhRMA), an indus-try trade group, re-ported that it willstart a voluntary reg-istry next month.Even pharmaceuti-cal executives ac-knowledge a prob-lem: “There is clear-ly a societal crisis interms of credibilityof drug company re-sults,” said JohnHayes of Eli Lillyand Co. in Indi-anapolis, Indiana, ata hearing in the House last week.
One source of trouble, advocates of aregistry say, is that clinical research suffersfrom “publication bias,” a tendency to trum-pet good results and bury the bad. A dramat-ic example came to the fore last year in acontroversy over the safety and effectivenessof antidepressant drugs in children (Science,23 July, p. 468). When the U.S. Food andDrug Administration’s (FDA’s) review of theantidepressant Paxil found that children tak-ing it had higher-than-expected rates of self-harm, Paxil’s maker, GlaxoSmithKline, re-leased a batch of unpublished studies. Thenewly released data suggested that Paxil wasineffective in treating their depression.Glaxo’s published study on Paxil in de-
pressed youngsters had suggested that itworked. FDA later admitted that only threeof the 15 pediatric antidepressant trials sub-mitted to it by various companies had foundthe medications effective.
At a hearing last week in the House En-ergy and Commerce Subcommittee onOversight and Investigations, FDA officialJanet Woodcock came under sustained firefor the agency’s re-luctance to releasenegative data sub-mitted by compa-nies. Legislatorsasked Woodcockwhether FDA had aresponsibility to themedical communityto publicize negative
results. She said, “This is a conundrum forthe agency,” which must normally protectproprietary information.
Observers trace the current furor to the1997 FDA Modernization Act, which offersdrug companies a 6-month patent extensionas a reward for testing drugs in youngsters.The legislation was prompted by the factthat many drugs approved for adults are of-ten prescribed to children “off-label.” Thelaw didn’t ensure that these study resultswould be released, however. A 2002 lawsought to remedy the data gap by requiringFDA to post online summaries of results ofall pediatric trials submitted to it for extrapatent protection.
But the problem is bigger than pediatric
testing, Representative Henry Waxman(D–CA) said at last week’s hearing. “Thepharmaceutical industry has systematicallymisled physicians and patients by suppress-ing information on their drugs,” he said.Waxman and Representative EdwardMarkey (D–MA) are crafting a mandatoryregistry bill in the House, while senatorsChristopher Dodd (D–CT), EdwardKennedy (D–MA), and two others are writ-ing a companion bill in the Senate.
The Waxman-Markey bill will hewclosely to recommendations made by jour-nal editors and the American Medical Asso-ciation, according to a statement released by
Waxman’s and Markey’s offices. It will de-mand disclosure of a trial’s objectives, time-line, eligibility criteria, and funding sources.It also will require that results be promptlyreleased. Because the bill’s authors are con-cerned that earlier attempts to create a publicregistry were not backed by enough muscle,a congressional aide says, this version willbe stringently enforced. For example, viola-tors may be subject to fines.
Pharmaceutical companies, meanwhile,are racing to set up their own registries orpledging to participate in PhRMA’s. “If weare running a trial, the public will know it,”says Lawrence Olanoff, executive vice presi-dent of Forest Laboratories in New YorkCity. Forest Labs, which makes the antide-pressant drugs Lexapro and Celexa, lastweek announced that it would set up a trialregistry as part of an agreement to end an in-vestigation by New York Attorney GeneralEliot Spitzer. Other companies, includingEli Lilly and Pfizer, have pledged to releasetrial information and results, although thedetails differ.
Still, some say voluntary registries mayprove disappointing, especially given thatpast attempts of this sort have faltered. Leg-islation “is the only route” to guarantee thata registry works, says Kay Dickersin, a clini-cal trials expert at Brown University in Prov-idence, Rhode Island. Even a mandatoryregistry, though, isn’t without potential pit-falls: Although she worries about “losing themoment,” Dickersin concedes that some trialresults could be confusing and will requirecareful handling when posted.
–JENNIFER COUZIN
Legislators Propose a Registry to TrackClinical Trials From Start to Finish
D R U G R E S E A R C H
N E W S O F T H E W E E KC
RED
ITS
(LEF
T TO
RIG
HT)
:RIC
K F
RIED
MA
N/C
ORB
IS;R
ON
SA
CH
S/C
ORB
IS
U.S. Clinical Registry Proposal May Require:
• Registering all U.S. drug trials at their launch
• Listing eligibility requirements for participants
• Listing funding sources
• Posting results, including those not published in journals
• Fining noncompliant trial sponsors
More data. Concerned about access to drug test data, Representatives Ed-ward Markey (left) and Henry Waxman are drafting a bill to require regis-tration of all clinical trials from their inception.
PYONGYANG—Ri Hak Chol leads the way outof the main building of the Institute of Ex-perimental Biology, under a façade declar-ing that “only our Great General lives, therest of us fight.” We walk past a volleyballcourt—the game is a popular lunchtime ac-
tivity at the institute—and enter a dim roomfilled with wooden cages and the pungentsmell of animals. Under a window letting inweak light on an overcast day, one of themost remarkable achievements of North Ko-rea’s scientific community sits passively be-hind bars: a white rabbit. It’s one of a half-dozen that Ri and his colleagues claim to
have produced since 2002 through somaticcell cloning, the technique that gave birth tothe famed Scottish sheep Dolly in 1997.
Western scientists may soon get thechance to scrutinize the cloning claim, pub-lished only in North Korea, and take themeasure of the country’s finest young scien-tists, including the 37-year-old Ri. In a mo-mentous shift in policy, the government ofthe Democratic People’s Republic of Korea(DPRK) this year has given a green light toselect scientists to team up with Westerncolleagues on joint research projects.
Some veteran watchers of the HermitKingdom say that its version of glasnost of-fers historic opportunities. Any light shed onthe country’s largely enigmatic scientificcommunity will help Western experts gaugeits capabilities. Moreover, the possibilitynow exists for an innovative brand of diplo-macy to proceed in parallel with traditionalchannels. “Scientific diplomacy can helpNorth Korean intellectuals to survive andcan inject, very gradually and cautiously,modern values into North Korea’s still veryisolated society,” argues Vasily Mikheev,chair of the Asia security program of theCarnegie Endowment for InternationalPeace in Moscow.
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1696
At once coy and eager, North Korea’s scientists are striving to forge new alliances with Western researchers without abandoning their unique philosophy of steely self-reliance
A Wary Pas de Deux
News Focus
Lapin-ectomy. A pair of young researchersperforms embryo transfer on a rabbit in a cleanroom at the Institute of Experimental Biology.
Visiting the Hermit KingdomNorth Korea rarely grants visas to foreign jour-nalists, and those it does invite are oftensteered to tourist zones or choreographedevents such as festivals. For the most part U.S.journalists are persona non grata. But earlythis year the North Korean government sig-naled a willingness to allow some scientists tointeract with Western peers. In June, a few
days after North Korea and the United States exchanged substantive proposals in nucleartalks in Beijing, the Academy of Sciences of the Democratic People’s Republic of Korea in-vited me to visit some of its premier labs. As part of the deal, I also got a fascinatingglimpse of life in this reclusive country.
On my first morning in Pyongyang I was awakened at 5 a.m. by a melancholy soundblaring from loudspeakers on the street. The melody, more than 3 minutes long, is titled“Where Are You Now, Our Great General?”—a hymn to Kim Jong Il, the current leader.His deceased father, Kim Il Sung, is the Great Leader. Except when preempted by occa-sional tests of the city’s air-raid sirens, the tune is played every hour on the hour fromearly morning to late evening. After a hotel breakfast of rice, fish, and kimchi (spicy pick-led cabbage), my escorts, one a conservation biologist and the other an academy officer,met me in the lobby. As we waited for the van to arrive, I noticed that the biologist waswearing a different loyalty badge from the previous day. All adults wear them, small pinswith the face of Kim Il Sung often set against a red background. “What happens if youforget to wear it?” I asked her. “Nothing, it’s not a problem,” she insisted before addingearnestly, “but we would never forget our Great Leader.”
As we drove across town later that day we passed the Grand People’s Study House,the city’s central library built in a majestic pagoda style—a refreshing departure from thegeneral vista of bland concrete office buildings and apartment towers. In lieu of trafficlights, shut off to conserve electricity, traffic wardens—attractive young women wearingwhite caps, smart white jackets cinched with brown belts with big silver buckles, royalblue skirts, and short white boots—stand ramrod straight in the middle of major inter-sections, their eyes darting in each direction before using batons to signal to drivers. Carsneed a special permit to operate on Sundays, so on that day the streets are nearly emp-ty—and the traffic women get a day off.
The few dozen scientists I met in North Korea struck me as warm, open-minded, andeager to cooperate with Western colleagues. Such collaborations will rely on the govern-ment’s good graces, of course. Nothing can be taken for granted: Government operationsare more opaque than ever, with Party conferences and other meetings once reported inthe state newspaper now held behind closed doors. “We have no idea how decisions aremade,” a Swedish diplomat told me. Yet my visit left me feeling that scientific exchangesare inevitable—and will benefit Koreans and Westerners alike. –RICHARD STONE
Exotic land. A tour guide wearing a tradi-tional hanbok at Tongmyong temple.
CRE
DIT
S:R.
STO
NE/
SCIE
NC
E
Science policy officials attuned to thepromising signals from Pyongyang arescrambling to seize the initiative. Nextmonth, for example, a three-member delega-tion from the Academy of Sciences of theDPRK (ASK), with sponsorship from theFord Foundation in New York City, is plan-ning to visit London to discuss with officialsand granting bodies the ground rules for po-tential collaborations. And a major sympo-sium on scientific cooperation with NorthKorea, to be held in Moscow, is in the worksfor April 2005.
Any joint project would entail some risk.There’s the matter of Juche, for starters. Theword stands for an all-encompassingcredo conceived by longtime leader Kim IlSung and described as a “man-centeredphilosophy” grounded in steely self-reliance. Some experts warn that Juchecould turn collaborations into a one-wayvacuuming of information and expertise bya regime that has recently set the world onedge over its attempts to develop what itcalls a “nuclear deterrent” (see p. 1698).Would-be partners must vet projects for po-tential usefulness to North Korea’s military,with the assumption that any equipmentand materials provided under a grant couldbe diverted for weapons R&D. “If there’seven the slightest possible military applica-tion, they will use it,” warns a Swedishdiplomat who has lived in Pyongyang.“That makes everyone very nervous.”
North Korean officials have reasons oftheir own to be anxious. Interactions be-tween their intellectual elites and Westernscientists inevitably would raise awarenessof modern Western life. With the Internetoff-limits to most North Koreans, the gov-
ernment has imported scientific informationprimarily through its diplomatic posts anddistributed it by means of a countrywide“intranet” (see p. 1701). A freer diffusion of knowledge couldundercut the chilling-ly effective cloak of naiveté about the outside worldthat the North Kore-an government hasdraped over its citi-zenry. “It could put astrain on the system,”says the Swedishdiplomat.
In an unpreceden-ted trip by a Westernjournalist, Science inJuly toured a handfulof ASK’s premierbiotech and computerscience laboratoriesand its science uni-versity. The picturethat emerged is one of dedicated scientiststoiling in largely antiquated and poorly sup-plied facilities—and hungry for contact withthe outside world.
Self-reliant scientistsAfter rising from obscurity to lead NorthKorea in 1945, Kim Il Sung, a former guer-rilla fighter against Japanese colonial rule,rapidly consolidated power and ruled theNorth until his death in 1994. Kim remainsthe country’s “president for eternity,” chemi-cally preserved and lying in rest in the lavishKumsusan Memorial Palace, his formerstate residence. After his death, the palace
was converted to a “supreme temple ofJuche,” displaying mementoes of his rule,including a railway carriage he used andhonorary awards such as doctorates and a
pin from an Italianlawyers’ association.Hewing to a songun,or “army-first,” poli-cy, North Korea isperhaps the mostheavily militarizednation in the world,with a standing armyof approximately 1 million soldiers and enough artillerytrained on Seoul—just 40 kilometerssouth of the Demili-tarized Zone, orDMZ, that separatesthe two countries—toobliterate the SouthKorean capital if warwere to break out.
Just below the military on the state’spedestal of honor is the scientific commu-nity. One of its heroes from North Korea’searly days is Li Sung Ki, a chemist whowith two Japanese colleagues during WorldWar II invented a polymer, vinalon, stillused in the production of everything fromclothing to f ishing nets. During the 2decades after the Korean War (called the“Fatherland Liberation War” here) ended in1953, the economy of the heavily industrial-ized North was booming. Seduced by theapparent economic miracle, Sweden got anearly foothold in North Korea, establishingan embassy in Pyongyang in 1975. It began
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1697
CRE
DIT
S:R.
STO
NE/
SCIE
NC
E
Leading the charge. A 10-meter-long mural at the Academy of Sciences’ Unjong regional branch depicts Kim Jong Il “giving guidance” to researchers.
Dead ringer? One of the claimed clones.
selling Korea everything from mining ma-chinery to Volvos, but even then North Korea wasn’t playing by the rules. “At firstthey paid for some of the stuff they bought,then they stopped paying and accumulated ahuge debt,” the diplomat says. Trade withSweden and the rest of Western Europedwindled.
Korean science, meanwhile, was flushwith cash into the 1970s, researchers say.“We were extremely well supplied by thestate,” says Choe Sung Ho, director of ASK’sInstitute of Microbiology. During the ColdWar, North Korea dispatched hundreds of itstop scientists for training in Soviet labs, in-cluding the Joint Institute of Nuclear Re-search in Dubna, as well as labs in the East-ern Bloc. But tensions between North Koreaand the Soviet Union were always near thesurface, especially as Kim’s government inthe 1970s began weaving a mythology abouthis life and the nation’s history. “We wouldtell them to cut down on the propaganda andfantasy—and that was coming from the Soviet Union!” exclaims Mikheev, whoserved as a diplomat in the Soviet embassyin Pyongyang in the early 1980s and returned to North Korea for a visit last July.
Relations quickly soured after the Soviet
breakup, to the extent that in the early 1990sseveral dozen Russian missile experts werearrested as they tried to travel to Pyongyang,Mikheev says. “Now there are no DPRKscientists working in Russian institutes,”says an official with Russia’s Ministry of
Science. North Korea’s on-again, off-againrelationship with China became more im-portant, and scientific ties between the twocountries increased. “Our country was in avery difficult situation,” says Ju Song Ry-ong, director of the Central Information
Agency for Science and Tech-nology in Pyongyang. “But ourGreat Leader set forth a ‘sciencefirst’ policy,” he says—raisingscience’s prestige, if not its fund-ing, to that of the military. TheNorth Koreans also cottoned onto one skill essential to enteringthe scientific mainstream. “Inthe past, we older scientistslearned Russian,” says Choe.“Now young people have cometo know that English is impor-tant for science.”
After the elder Kim’s deathin 1994 and a series of devastat-ing floods and crop failures,Kim Jong Il, echoing his father’swords, turned to his scientistsfor a way out of the country’smiseries. Kim has called scienceand technology one of three pil-lars for building a prosperous
N O R T H K O R E A
CRE
DIT
:R.S
TON
E/SC
IEN
CE
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1698
Nurture then nature. After raising acacia shoots in culture fora month, Un Song Gun’s group transfers the hardiest specimensto the field, where the trees grow about 2 meters per year.
Nukes for Windmills: Quixotic or Serious Proposition?PYONGYANG—The Democratic People’s Republic of Korea (DPRK)often resorts to fiery rhetoric when faced with challenges from theoutside, but it knows about conciliatory tactics as well. Indeed, anunofficial envoy who spoke with Science here in July claimed thatthe government is ready to make a remarkable concession: Itwould abandon its nuclear program in its entirety—both weaponsand power generation—in exchange for “clean energy technolo-gies” such as wind power. The proposal, if backed by the govern-ment, could set the stage for progress in high-level discussionsover the fate of North Korea’s nuclear program. But like many oth-er signals from Pyongyang, this one is hard to interpret.
“It’s the first time we’ve heard of [trading nuclear power forclean energy technologies]. It’s very intriguing,” says Mikio Mori,who until last month was director for multilateral nuclear coopera-tion in Japan’s Ministry of Foreign Affairs. That fits with what KimJong Il, leader of North Korea, told Japan’s prime minister, JunichiroKoizumi, in talks in Pyongyang last June. “He tried to persuadeKoizumi that having nuclear weapons is not in [North Korea’s] ben-efit and that dismantlement is their final objective,” Mori says. A re-quest for clean energy technologies would be “a big plus, very posi-tive,” adds Robert Alvarez, a former senior policy adviser to the U.S.Department of Energy (DOE) who helped implement the AgreedFramework, a 1994 accord in which North Korea agreed to moth-ball its plutonium facilities for energy aid and other incentives. Al-varez is now at the Institute for Policy Studies in Washington, D.C.
Representatives of six countries—China, Japan, North Korea,Russia, South Korea, and the United States—have met intermit-tently since August 2003 to try to solve a crisis stemming fromNorth Korea’s efforts to acquire what it calls a “nuclear deterrent.”At the most recent round of talks last June, North Korea proposed
what it terms a “reward for freeze”: energy aid in exchange for apromise to suspend its plutonium program once again. The UnitedStates, in contrast, offered that non-U.S. parties would provideheavy fuel oil only after North Korea agrees to dismantle all itsnuclear programs. “There are major gaps between the North Koreaand U.S. proposals,” says Mori. “We need to define clearly what theparties want.” The next round of talks had been expected to takeplace in Beijing later this month. However, revelations about uranium-enrichment experiments in South Korea and a recent flare-up inthe war of words between North Korea and the United Statesthreatened a delay until after the U.S. presidential elections.
The true nature of North Korea’s “deterrent” is far from clear. Thecountry’s ambitions to build a nuclear weapon first came to light inthe late 1980s.At a meeting of deputy foreign ministers of Soviet blocstates in Pyongyang in 1988, North Korean officials leaked to the So-viet Embassy that their military had started a nuclear weapons pro-gram, says Vasily Mikheev,Asia expert for the Carnegie Endowment forInternational Peace in Moscow. After an investigation, the KGB con-cluded that it was unlikely—but not impossible—that North Koreacould devise a working bomb, Mikheev says. Russia’s opinion remainsunchanged, he says: “North Korea has a nuclear weapons program, butthere is no reliable proof that it can produce nuclear weapons.”
U.S. analysts are more bullish on North Korea’s odds of pulling itoff. “Per capita, the DPRK has probably invested as much in itsweapons programs as the Soviets did,” notes a State Department offi-cial. Erring on the side of caution, perhaps, the CIA estimates thatNorth Korea has made as many as eight plutonium bombs. At theYongbyon nuclear facility last January, North Korean scientists showedwhat appeared to be plutonium metal to a delegation includingSiegfried Hecker, senior fellow and former director of Los Alamos Na-tional Laboratory in New Mexico (Science, 23 January, p. 452). But thejury is out on whether Korea’s nuclear specialists have devised theprecise configuration of explosives needed to get a plutonium bomb
nation, the other two pillars being ideologyand the military. In a 1997 treatise on Juche,he proclaimed the necessity of “expandingand developing scientific and technical ex-changes with different countries and intro-ducing advanced science and technologyfrom other countries.” The policy statementreaffirms a core Juche principle: “There’sno restriction on North Koreans using theoutside world for their own betterment,”says the Swedish diplomat.
Ambiguity about whether Kim’s guid-ance meant that North Korean scientists hadcarte blanche to reach out to the West orwhether it implied a more furtive acquisitionof knowledge from abroad prevented anysignificant movement, however. But in re-cent months, government missives haveclarified the situation: ASK and universityresearchers have explicit orders to bring inforeign grants whenever possible. Still, lackof contacts—especially e-mail links—andfunds continue to present major barriers.
Today North Korea claims to have 1.8million “intellectuals,” including an esti-mated 100,000 working scientists. But thestate has the means to pay only utility billsand meager salaries. ASK scientists earnbetween $20 and $40 per month at the of-
f icial exchange rate, but one-tenth that at the black-marketrate. Institutes have scant fundsfor foreign travel, and these arelargely reserved for train ticketsto China for training courses.
Even so, a substantial propor-tion in this favored occupation isdoing better than their compatri-ots, who in rural areas must ekeout a hardscrabble existence. Forresidents of Pyongyang, at least,the Communist-style food distri-bution system introduced by KimIl Sung remains intact, providingmonthly rations of staples such asrice, bread, and eggs. “We knowvery little about who’s gettingwhat and why,” says the Swedishdiplomat. Scientists still receive rations, saysan ASK official.
A party policy paper published lastmonth in the state newspaper Nodong Sin-mun reaffirms science as a high priority, de-claring: “It is our party’s unwavering deter-mination and will to raise the country’s sci-ence and technology to the world standard ina short period of time and, based on this, toopen up a phase of turnaround in the con-
struction of a powerful state.” Juche or no,North Korea can’t do this alone. Many fac-tories are shuttered due to a lack of energyand raw materials, and there is little privateenterprise. “The North Korean economy isin a very deep crisis,” says Mikheev.
Science for the massesNorth Korea’s homegrown civilian science,at least the portion that Science was allowed
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1699
CRE
DIT
S (T
OP
TO B
OTT
OM
):SP
AC
EIM
AG
ING
INC
.;R.
STO
NE/
SCIE
NC
E
to fission. A global surveillance network assem-bled under the Comprehensive Test Ban Treatyhas not picked up the telltale seismic signals of asuccessful nuclear test in North Korea. “As far aswe know, no testing has been done,” says Tet-suya Endo, vice chair of Japan’s Atomic EnergyCommission. (Western experts are, however,keenly watching a recent flurry of activity atsuspected test sites in North Korea.)
More alarming is the prospect of North Korea enriching uranium, analysts say, becauseit’s easier to get a uranium bomb to undergo fis-sion. That concern triggered the current crisis. InOctober 2002, U.S. diplomats confronted theirNorth Korean counterparts with evidence thatthe reclusive state was secretly attempting toenrich uranium. Although the U.S. dossier hasnot been made public, elements have beenleaked. For example, U.S. officials claim that A. Q.Khan, the father of Pakistan’s nuclear program,has admitted to having provided North Korea inthe 1990s with nuclear technology, including a design for a gas cen-trifuge for concentrating weapons-grade uranium. North Korea alsomay have imported equipment for an enrichment facility through Ko-rean-run export companies in Japan. “We have a history of stoppingexports from Japanese companies,” says Mori.
Japanese and U.S. officials who spoke with Science acknowledgethat they have few clues to the location of the uranium-enrichmentprogram or how advanced it is. “No one has seen it,” says Mori. NorthKorean officials steadfastly deny that a uranium program exists. Thathas thrown up a hurdle at the six-way talks, in which Japanese andU.S. officials have insisted that the uranium program’s dismantlementis integral to any deal. “It’s a major stumbling block,” says Mori.
Despite the political barriers, U.S. nonpro-liferation officials see a tantalizing possibilityin these negotiations. They may offer a way toredirect North Korea’s nuclear scientists—andperhaps even its cadre of researchers involvedin biological and chemical weapons R&D—topeaceful research. According to one U.S. offi-cial, there may be several hundred North Ko-rean weaponeers “of interest.”
Still unknown is whether theNorth Korean government will echothe unofficial suggestion that it isready to abandon its nuclear pro-
gram for clean energy technologies. Inaddition to describing this possibility,
the unofficial envoy—who spoke withScience at an unusual meeting arranged by
other diplomats—reiterated old themes: thatNorth Korea desires bilateral talks with theUnited States to solve the nuclear issue and
that it is ready to discuss diplomatic relationsbetween the two countries.
A State Department official told Science that the U.S. governmentis preparing to raise the amount of aid offered to North Korea in thenext round of talks in exchange for dismantling the uranium program.The prospect of a better deal would strengthen the hand of advisers toKim Jong Il who advocate cooperation with the United States, arguesMikheev. But the U.S. commitment will need to be solid, he says,adding that North Korea is unlikely to settle for anything less than anagreement ensuring the present government’s survival.After all, its nu-clear program is its only real bargaining chip. “Without nuclearweapons North Korea would be just a poor country with no atten-tion,” asserts Endo.“Kim Jong Il is fully aware of that.” –R.S.
Plutonium produc-tion line. The repro-cessing facility atYongbyon.
N E W S F O C U S
Still life. The Biology Branch’s museum room displays pick-led critters from across the country.
to glimpse, is mostly tied to areas of poten-tial economic growth. A plant genetics labhas introduced a line of virus-resistant pota-toes into commerce and is trying to transferinsect-resistant Bacillus thuringiensis genesinto corn, rice, and oilseed rape. Chineseagricultural scientists have come to NorthKorea to collaborate on transgenic experi-ments, including field trials, says Kim SongJun, director of the Branch of Cell and GeneEngineering. Another team is growing aca-cia shoots in tissue culture to clone thehardiest trees. “Many trees were cut downfreely during the Korean War and after thewar,” says Un Song Gun, chief of the insti-tute’s tissue culture lab. “We’d like to refor-est entire mountains” with both importedand native acacia varieties, he says.
Other efforts aim to improve publichealth. One team, for example, is cloningthe gene for erythropoietin, a hormone thatstimulates the body to make blood cells,with a goal of infusing the protein in anemicpatients. So far they have succeeded in ex-pressing the gene in Chinese hamster cells.Another group extracts tetrodotoxin frompuffer fish for use as a drug to treat tubercu-losis, a particular scourge in North Korea;plans are afoot to export the preparation toChina and Vietnam. Malaria is another woe,with approximately 300,000 cases per year.And an untold number of children are mal-nourished. The Swedish diplomat puts itbluntly: “A very ordinary disease in the Westwill kill you here. If you’re malnourishedand get the flu, you’re dead.”
The World Health Organization aims tocombat this health crisis by stepping up itssupport to North Korea. Until last yearWHO was mainly providing medicine andequipment to North Korea’s Ministry ofHealth. “The plan now is to provide moretechnical expertise,” including assistance fortraining North Korean public health special-ists abroad, mainly in Thailand, says DiegoBuriot, a WHO special adviser who traveledto Pyongyang last year to initiate these dis-cussions. He and other WHO officials havealso floated the idea with their North Koreancounterparts of organizing an internationalconference in Pyongyang to review commu-nicable disease surveillance systems in theregion, with a goal of improving informa-tion exchange.
Also hoping to make inroads into easingthe country’s health woes is ASK’s Instituteof Microbiology, which specializes in me-dicinal polysaccharides. One preparation,Jangmyong, is a pair of polysaccharides de-rived from mushrooms that grow on pinetrees. It is touted as an immune-systembooster—it’s claimed to rev up T cell pro-duction in bone marrow—for curing every-thing from brain cancer to epilepsy.Jangmyong is now being exported to China,
Japan, Malaysia, and South Korea, says itsdeveloper, Mun Ho of the Institute of Mi-crobiology. Further work is stymied by ashortage of supplies, says Mun: “There aremany polysaccharide standards in the Sig-ma catalog we would like to have, butthere’s no way to buy them.”
Closer to the ethical fringe, the NorthKorean government has a policy of adminis-tering human growth hormone to all chil-dren, aged between 12 and 15, who aredeemed “unusually short”—less than 140centimeters tall. The injections add about 1
centimeter in extra growth per year, saysKim Song Jun. His institute is conductingclinical trials of growth hormone for use inpromoting health, from improving metabo-lism and softening skin to promoting fasterrecovery after operations.
The pride of ASK’s Biology Branch is itsclaimed cloning breakthrough. The impetuswas a visit by Kim Jong Il to the Institute ofExperimental Biology on 13 June 1999.Kim’s appearances at institutes, and farmore frequently at bases of the People’sArmy, are portrayed as opportunities to“give guidance” to his people. During the1999 visit Kim “came to know that welacked equipment,” says branch presidentSon Kyong Nam; Kim later “personally”provided the institute’s Cloning and Repro-ductive Technology Center with a cen-trifuge, microscopes, and other equipment.Also crucial were key articles on cloningfrom overseas sent back by North Koreanofficials. Armed with equipment and knowl-
edge, the team—“almost all of them youngscientists,” says Kang Gyu Chol, scientificand technical counsellor at the DPRK Em-bassy in Moscow—set to work.
After producing cloned rabbits usingembryo transfer, the researchers claim theysucceeded through trial and error in the farmore diff icult technique of somaticcloning. The f irst such pair of rabbits,cloned from fibroblasts derived from a 15-day-old fetus, was born on 1 July 2002. Iftrue, that would mean that the group wasthe second in the world to clone rabbitsfrom somatic cells. The first North Koreanpair proved fertile, and the lab has sinceproduced two more pairs, the latest born inAugust 2003. Ri notes that Kim Jong Ilpersonally thanked the group for its break-through. The cloning center also has a keeninterest in launching a stem cell researchprogram with Western assistance, with theultimate aim of developing treatments forparalysis and kidney diseases.
Breeding supergoatsThe experimental farm where ASK intendsto raise its agbiotech game lies an hour’sdrive east of Pyongyang. Our journey be-gins on a six-lane highway leading out ofthe city. Traffic is heavy—but it’s not vehic-ular. Scores of people, adults and children,some bedraggled, are walking along theshoulders of the quiet road; public trans-portation outside Pyongyang appears to bevirtually nonexistent. Occasionally we passa farmer driving an ox yoked to a woodenplow. After about a half-hour on the high-way we turn off onto a bumpy dirt road thatwends through a broad valley lined withjagged hills, past cornfields and rice pad-dies and the occasional long, wooden signwith white letters on a red background ex-tolling the glory of Kim Il Sung. It’s therainy season, and in a few spots the rivershave overflowed their banks, washing outthe road. Our van forges ahead.
We pull into one of ASK’s experimentalfarms. “This doesn’t look like much now,”says Son, nodding to a collection of sparewooden outhouses and pens. He has bigplans to transform the farm into a stockbreeding center for the creation of herds ofsupergoats using embryo transfer andsomeday, he hopes, cloning. “This is ourbase for the introduction of embryo trans-fer throughout the country,” he says. Thestate recently approved the construction ofa facility to house several hundred elitegoats—breeds that ASK hopes to importwith Western money—as well as labs forreproductive technologies.
Mountains cover roughly 80% of NorthKorea, leaving little arable land, and thecountry has suffered from crop failures inrecent years. Thus in the late 1990s the
N O R T H K O R E A
CRE
DIT
:R.S
TON
E/SC
IEN
CE
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1700
One giant leap. Asia expert Vasily Mikheev, anadvocate of science diplomacy, with two Korean colleagues at the Goethe Institute’snew reading room in Pyongyang.
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1701
CRE
DIT
S:R.
STO
NE/
SCIE
NC
E
The Ultimate, Exclusive LANPYONGYANG—North Korea’s success in integrating itself with therest of the world, beginning with science, could hinge on whetherit opens up lines of communication to foreign information andideas. But that’s a risky notion in this isolated country.
Leader Kim Jong Il inherited from his father, Kim Il Sung, a dis-trust of alien influences and an enthusiasm for technology. Thisskittishness is embodied in North Korea’s strategy for importingand disseminating technology. Spearheading the effort is the Cen-
tral InformationAgency for Scienceand Technology(CIAST). By themid-1990s CIASThad developed itsown database en-gine and in 1997began installing anational computernetwork—a simu-lation of the WorldWide Web that’sunconnected tothe outside world.
Ri Hyok, whoheads CIAST’s Com-puter Center, shows
off the home page for the countrywide intranet (one your browserwill never find). It’s as slick and easy to navigate as Yahoo. It providesaccess to tens of millions of records, according to Ri, including severalonline North Korean journals, a science encyclopedia, and a wealth ofanalytical information compiled by a 600-strong staff on topics fromagriculture and construction to the writings of Kim Il Sung. The sys-tem, called “Kwangmyong,” or “light,” was upgraded recently withfiber-optic links to major North Korean cities and now has approxi-mately 10,000 subscribers, says Ri. Subscriptions are free; users onlypay telephone charges. “We don’t know how their intranet works,”confesses a Swedish diplomat. CIAST says it raises funds through theexport of software, such as a Japanese-Korean translation programnow being sold in Japan and other countries.
Ri says he and his CIAST colleagues are keen to boostcapacity and access Western literature electronically. Thatwould be straightforward if they could tap external Websites. Asked whether there are plans to connect to the Web,Ri offers a strained smile. “No plans,” he says.
The Academy of Sciences has external e-mail—a singleaddress for the entire organization. (Internet access inNorth Korea is restricted to a small, trusted fraction of thepopulation.) If CIAST were to make portions of its Web siteavailable to the outside world, it could solicit external fund-ing or collaborators. But for now that’s not feasible, says Ri:“It’s an administrative issue.”
Access to up-to-date scientific information throughprinted books and journals is also lacking. On a leafy cam-pus a half-hour’s drive south of Pyongyang, the Academy ofSciences runs an intellectual hothouse—the University ofSciences, part of its Unjong regional branch. This university, with astudent body of 3000, cherry-picks “genius” students fromthroughout the country, of which 60% continue in postgraduatestudies, say university officials. Faculty members, including about100 Ph.D. lecturers and professors, also maintain laboratories thatwork on everything from the production of cisplatin for cancer
therapy to studies of laser-ignition of dynamite and a magne-tometer for detecting hidden weapons. The university’s Korean-Chinese Friendship Laboratory features a laser setup, donated byChina more than a decade ago, for the study of plasmas.
Yet a glimpse of the university’s library shows how disconnect-ed the students and faculty may be. It’s a Friday morning; classesare in session. But the reading room, desks aligned to face the vis-age of Kim Il Sung, is deserted except for a solitary librarian. Whenasked for examples of the library’s English-language science jour-nals, the librarian disappears momentarily into the stacks, a roomno bigger than a 7-11 store. She retrieves a half-dozen issues,bearing the treasures to her desk. They look old, and they are. Anissue of the Journal of Quantum Electronics from 1977.Genetics—1981. Microelectronics—1973. A generation of sciencehas passed them by.
Some foreign organizations have tried to help fill the informa-tion void. For example, the Asia Foundation, with headquarters inSan Francisco, has provided more than 70,000 books and journalsto the Grand People’s Study House, or central library, Kim ChaekUniversity of Technology, and Pyongyang University for ForeignStudies, all of which are in Pyongyang. And the Goethe Institute ofBerlin last June opened a reading room with some scientific litera-ture in the Chollima House of Culture in Pyongyang. Still, as theSwedish diplomat observes, the vast majority of North Koreans“have very little idea of the outside world.”
Sometimes the government’s efforts to catch up are too quickfor its own comfort. Last year it launched a cell phone network, is-suing about 10,000 handsets, estimates a Russian diplomat. Hesays that within a few days after the deadly train explosion atRyongchon last April, which occurred several hours after Kim JongIl’s train from China passed through the station, the governmentbegan recalling most of the phones. The network is still operat-ing—diplomats in Pyongyang say they use it for their cellphones—suggesting that some North Korean elites have kepttheir handsets. It’s unclear why the government clamped down, al-though the diplomat speculates that it is nervous about “horizon-tal communication.” Perhaps, he says, in the hours after the Ryongchon accident, the cell network was abuzz with gossip overwhether the explosion was an assassination attempt, an idea thathas since been discounted.
“To achieve a free flow of people and knowledge, the societyhas to be ready,” notes Mikio Mori of Japan’s Ministry of ForeignAffairs. For now North Korea’s intellectual community is extendinga hand to the outside world with trepidation, unsure of who willgrasp it or how new contacts may shape the country’s future.
–R.S.
North Korean Webmaster. Ri Hyok’s team atCIAST has built a formidable countrywidecomputer network.
Missing student bodies. On a Friday morning, the University of Sciences’ li-brary does not appear to be a top draw.
N E W S F O C U S
government made it a policy to raise theproductivity of goats and rabbits, whichare adept at grazing on rough terrain. (Aswith all major policy decisions, Kim JongIl is credited with the inspiration to breedbetter goats.) Native goats produce be-tween 150 and 200 liters of milk a year,whereas a Swiss breed, Saanen, can churnout much more. ASK has fewer than adozen Saanen and wants to purchase acouple of hundred next year.
After conquering embryo transplantationin mice in 1988, Son says, a year later NorthKorean scientists succeeded with artificialinsemination and surgical transplantation ingoats. Son says Korean scientists hope toimprove their skills through training and ul-timately move to nonsurgical embryo trans-fer. By transferring embryos of Saanen orother well-bred species into native goats,they hope to multiply their herd of elitegoats to more than a quarter-million by2010. Also on the agenda is impregnatingindigenous goats with Saanen sperm, withthe aim of breeding more than 4 million hy-brids in the next 5 years.
“The overall goal is to meet the needs ofour people for meat and milk by develop-ing and applying new reproductive tech-niques,” Son says. But research materialsare in short supply. “We feel the lack of in-frastructure,” says Son, who notes that hisresearchers have had to improvise, for ex-ample by using special methodology forfreezing and preserving sperm with Soviet-era equipment. “Importing new equipmentwould not be a problem,” he says.“The only problem is money.”
Well, not quite the only prob-lem. One expert with a U.S. non-profit that has worked extensivelywith North Korea to provide agri-cultural assistance says that thegoat-breeding proposal “is typicalof the ideas we have seen and re-ceived: too much, too fast, an em-phasis on high-tech solutionsrather than basic management, andan underestimation of the technicalresources needed to initiate theproject.” He cites a cautionary talefrom his own experiences in Ko-rea. A few years ago the organiza-tion shipped purebred boar and bull semento the DPRK Academy of Agricultural Sci-ences to upgrade their herds. The academyfailed to inseminate any cows and producedonly two small litters of pigs. Although itwas unclear where the problems lay, the ex-pert concludes that “they were clearly sub-stantial for such an abysmal result.” Never-theless, he says, aid organizations should beready “to support something reasonable inthis area of work.” He envisions a projectthat could involve training a handful of
North Korean scientists abroad to bringthem up to speed before providing equip-ment and reagents. “Otherwise it will justget wasted,” he says.
Goats are not the only animal on themenu. In the early 1990s, ASK researcherscollaborated with a Czech team on embryotransfer in cattle, and they hope to trycloning as well. On a hill a few hundred me-ters away, workers are laying cinderblocksfor the facility to conduct such experimentson goats and cattle. “Our government is pay-ing much more attention now to this site, be-cause it’s a place where we can link scien-tists and farmers,” says Son. “At the end ofthis year it will be ready.”
One thing that would help is a betterroad. On the way back to Pyongyang ourvan, avoiding a washed-out section of road,got stuck in a gully. A passing unit of thePeople’s Army, mostly boys in their lateteens, appeared out of the blue and pushedthe van out. I decided to keep my mouthshut, recalling my visit the previous day tothe War Museum in Pyongyang, where Iwas told that America’s “puppet regime” inthe South attacked the North to start the Ko-rean War in 1950—exactly the opposite ofwhat the rest of the world is taught. There Ihad heard a litany of war crimes and cow-ardly acts that the North Koreans attribute toU.S. forces. “You can understand why wehate Americans,” one of my escorts had ex-plained in a rectitudinous tone. If it weren’tfor the unwitting assistance the soldiers pro-vided to the enemy—North Korea and the
United States are still technically at war—we might have been stuck there all night. Iwondered, though, whether U.S. scientistswould have to bear such enmity for the sakeof a joint project.
Promises and perilsNearly a half-century ago, when the SovietUnion in 1957 launched Sputnik, the world’sfirst satellite, many observers feared that theSoviets had overtaken the United States inthe physical sciences. But because there was
virtually no contact between the Soviet andU.S. scientif ic communities, westernerscould only speculate. By 1959, the U.S. Na-tional Academy of Sciences (NAS) hadstruck up a scientific exchange programwith its Soviet counterpart, in which approx-imately 20 specialists from each superpowervisited the other. The U.S. side quicklygleaned that fears of Soviet scientific domi-nance were overblown. “The myth of the su-periority of Soviet science would not havespread so far if scientific contacts with theSoviet Union before 1957 had not been sofew,” concluded an influential 1977 reviewof the exchange program by an NAS panelchaired by political economist Carl Kaysenof the Massachusetts Institute of Technolo-gy. The exchanges, the Kaysen report con-cluded, achieved “striking success” in learn-ing about Soviet strengths in science andgenerally improving U.S.-Soviet relations.
The model may work for North Koreaas well, but—as with the Soviets—thereare risks and benefits to consider. On theone hand there are tantalizing opportuni-ties to expose Korean scientists, some ofwhom may exert influence on future gov-ernments, to Western ideas. Engagingthem could strengthen the positions “ofthose in North Korea who hopefully willbe able to support reforms if, or when,they start,” says Mikheev.
But on the other side are concernsabout so-called dual-use technologies: thepotential diversion of equipment from be-nign research to weapons R&D. That could
doom some projects before theyget off the ground. “Strong con-trol is needed over what kind ofequipment and supplies will beprovided to North Korea,” saysMikheev. The Institute of Micro-biology, for example, would liketo expand its work on medicinalpolysaccharides. “We need fer-menters,” says institute directorChoe, who notes that quality fer-menters can cost thousands ofdollars. But fermenters, a majorquarry of weapons inspectors inIraq, could be diverted for use incooking up pathogens.
Dual-use concerns boil down toa dearth of trust. “We run into a problem:Who are we talking to?” says the Swedishdiplomat. “Is it really a biochemist, or is it acolonel in the army? Or the head of theirbioweapons program? We have to try tofind programs that will not strengthen theirmilitary or boost their economy at thisstage.” In negotiations on a cooperationagreement last year with ASK, Russian of-ficials steered discussions away from activi-ties that could involve dual-use technolo-gies. “We agreed to exchange open, unclas-
N O R T H K O R E A
CRE
DIT
:R.S
TON
E/SC
IEN
CE
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1702
Window to the world. The Asia Foundation has donated thousandsof books and journals to the Grand People’s Study House (center).
sified scientific literature,” saysthe Russian science ministry of-ficial. North Koreans, too, arewary, assuming that foreign visitors have government con-nections, no matter what their affiliation.
Overcoming such suspicionswill require that joint projects befundamentally benign or benevo-lent. “Projects should be basedon humanitarian needs,” saysShunichi Yamashita, chair of theAtomic Bomb Disease Instituteat the University of Nagasaki,who has worked extensively onscientific aid projects in the for-mer Soviet Union. One area thatgets top marks as a confidence-builder is the environment. In arare joint effort with South Ko-rea, for example, ASK’s BiologyBranch is translating into Englisha compendium on North Korea’sroughly 4000 native plants.
Agricultural exchanges toohave borne fruit. For example,the American Friends ServiceCommittee (AFSC), a Quaker-founded nonprofit, has broughtNorth Korean delegations to theUnited States, China, and Viet-nam to study topics such as riceand corn breeding, potato seedgeneration, and poultry produc-tion. “The North Koreans canfreely interact with researchersand have an extremely valuableopportunity to acquire copies ofjournal articles, research re-ports, and other published information,”says AFSC program representative RandallIreson, who has traveled to North Korea.The study tours, he says, have resulted in,for example, more economical feed formu-lation for poultry and swine, better ricebreeding, and the use of legume covercrops for improving soil fertility.
University exchanges also could buildbridges. Since 2002, the German Acad-emic Exchange Service (DAAD) has sponsored exchanges between Germanuniversities and several institutions in Pyongyang, including Kim Il Sung Uni-versity, ASK, and the Academy of Agricul-tural Sciences. Academic relations “areimproving steadily,” says DAAD’s UrsulaToyka-Fuong, with plans in 2005 to invitetwo Korean researchers for long-termstints in Germany, as well as offer short-term scholarships for up to 6 months toseveral promising young scientists.
A similar exchange program with KimIl Sung University was launched last yearby Far Eastern National University in
Vladivostok, Russia, which already hadSouth Koreans among its student body. “Atfirst the North Koreans and South Koreansgot into a lot of fights. It was a big problemfor us,” says Valery Dikarev, vice presidentfor international affairs at Far Eastern. “Butat the end of the year the South Koreanssaw off the North Koreans at the train sta-tion—and they all were crying.” Dikarevvisited Pyongyang in July as part of a dele-gation to expand Far Eastern’s academicagreement with Kim Il Sung University toinclude joint research; initial projects willprobe the biochemistry of traditional Kore-an medicines. Kim Il Sung University’seconomics institute, meanwhile, has askedthe Swedish Embassy to help devise im-proved course materials. “I find it intrigu-ing that we can change their curriculum,”says the Swedish diplomat.
The United States sees an entrée as well.Syracuse University in New York and Kim Chaek University of Technology in Pyongyang have exchanged delegations andare working to establish twin laboratories for
joint research on integrated infor-mation technology. The project,funded by the Henry Luce Foun-dation and the Ford Foundation,suggests “the possibility of seri-ous, sustained, and mutually ben-eficial collaborations between aninstitution in the DPRK and onein the U.S.,” according to a recentstatus report from the team.
Another budding initiative isa U.S. committee now being or-ganized with members fromsome 50 nonprofits, universi-ties, and other organizations toengage North Korea in a rangeof areas, including science. AndNAS and the U.S. NationalAcademy of Engineering (NAE)are discussing ways to cooper-ate with ASK on energy andagricultural projects. The dis-cussions were initiated in Pyongyang last January bySiegfried Hecker, senior fellowand former director of LosAlamos National Laboratory in New Mexico and a memberof NAE’s council. Hecker isnow serving as a liaison be-tween the U.S. and North Kore-an academies.
“I’m convinced there are interesting research programs inNorth Korea, including thoseinteresting to world science. We just have to discover andsupport them,” says ZurabYakobashvili, director of the In-ternational Centre for Scientific
and Technical Information in Moscow,which is helping to organize a symposiumnext spring to bring together North Koreanand Western scientists to discuss jointprojects in areas such as biotechnology, in-formation technology, and materials sci-ence. North Korea’s rank-and-f ile re-searchers are raring to go. “We have manyyoung scientists who are very well quali-fied,” says Choe. “If even one is able totravel to Europe, we can learn a lot. Butnow we’re just sitting here.”
Mikheev, who has long advocated acautious approach to North Korea, viewsscientific cooperation as an exceptionallyconstructive tool for engaging the DPRK.“From a strategic perspective, scientificdiplomacy seems to be very important toprovide peace on the Korean Peninsula,”he says. Forging contacts with key individ-uals could well help shape North Korea’sfuture and give rise to the exhilarating pos-sibility of bringing an entire nation in fromthe cold.
–RICHARD STONE
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1703
CRE
DIT
:R.S
TON
E/SC
IEN
CE
Raring to go. Many scientists want to go abroad for training, says ChoeSung Ho of the Institute of Microbiology. “But now we’re just sitting here.”
N E W S F O C U S
www.michigan.org MICHIGAN GREAT LAKES. GREAT LOCATION.
TREES INSPIRED DR. TOMALIA’SNANOTECHNOLOGY DELIVERY SYSTEMS.
Dendrimer molecules have hundreds of nano-scale branches that
can deliver medication, diagnose heart attack victims, root out
cancer cells, even sow the seeds for better gene therapy.
They’re growing right now at Dendritic NanoTechnologies, Inc.
the company Dr. Tomalia founded and built into the world’s lead-
ing dendrimer research and manufacturing center. All from the
SmartZoneSM technology cluster located on the campus of
Central Michigan University in Mount Pleasant, Michigan.
Why Michigan? With our business climate ranked #2 in the
nation by Site Selection magazine, and one of the fastest-grow-
ing life science corridors anywhere, we make business and sci-
ence work like no place else.
Dendritic NanoTechnologies, Inc. is just one of the exciting com-
panies that make up Michigan’s Technology Tri-Corridor, which
includes Life Sciences, Advanced Automotive Technology, and
Homeland Security.
To learn how Michigan can help your business grow,
call 1.800.946.6829 or visit www.michigan.org.
HE PLANTED HIS COMPANY IN
MICHIGAN.
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1705
CRE
DIT
:R.M
UN
DI/
BERK
ELEY
GEO
CH
RON
OLO
GY
CEN
TER
For earth scientists trying to lay the blamefor the all-time greatest mass extinctionsome 250 million years ago, the secret is inthe timing. The professional timekeepers—the geochronologists—are trying to place avolcanic catastrophe at the moment of theextinction, thus linking cause and effect toexplain an event that wiped out 95% of an-imal species on Earth.
But nailing down the time of the Permi-an-Triassic (P-T) extinction has revealedproblems in the often competitive businessof geochronology. P-T daters must drawtheir conclusions from vanishingly smallisotopic remains of radioactive decay. Foryears, different laboratories using uranium-lead radiometric dating—the gold standardof geochronology—have been getting en-tirely different ages for the P-T extinction.
On page 1760 of this issue of Science,Roland Mundil of the Berkeley Geo-chronology Center in California and col-leagues weigh in with their latest P-T ageusing a new way of preparing samples foruranium-lead dating. By their reckoning,the extinction and the largest volcanic erup-tion of all time are older than thought, butcoincided precisely. “It’s an impressivepiece of work,” says geochronologistMichael Villeneuve of the Geological Sur-vey of Canada in Ottawa. The new treat-ment seems to remove much of the subjec-tivity of traditional approaches, but still, “alldates are interpretations,” Villeneuve notes.“It needs a bit more proving out.”
Uranium-lead dating seems straightfor-ward enough. The analyst simply crunches arock, picks out microgram grains of themineral zircon, grinds off an outer layer, dis-solves the remaining grain in acid, spikes thesolution with a calibration standard, andmeasures the amounts of four isotopes usingmass spectrometry. Two are isotopes of ra-dioactive uranium that have not yet decayed,and two are picogram quantities of lead iso-topes that have accumulated from the steadydecay of the uranium since the zircon crys-tallized in magma. The ratio of each urani-um isotope to its decay-product lead isotopetells how long each of the two radioactiveclocks has been running and thus how oldthe rock is.
Geochronologist Samuel Bowring of theMassachusetts Institute of Technology andcolleagues followed just such an approach todate rocks bearing fossils from the time of
the P-T extinction in southern China. Ana-lyzing zircons from nearby layers of vol-canic ash, they got an age of 251.4 ± 0.3million years (Science, 15 May 1998, p.1039). And late last year Sandra Kamo ofthe University of Toronto, Canada, and col-leagues published a uranium-lead date of251.4 million years—right on Bowring’s P-Tage—for the eruption of the massive Siber-ian Traps, thick layers of ancient lava thatonce covered millions of square kilometers(Science, 21 November 2003, p. 1315).
Mundil, however, doesn’t believe thateither the eruption or the extinction hap-pened that recently. He thinks Bowring en-gaged in “arbitrary data culling” by throw-ing out more than half his zircon ages be-fore averaging the rest of them together.But Bowring says his choices were judi-cious, although “necessarily somewhatsubjective.” In some of his zircons, the twodifferent uranium-lead ratios gave differentages, suggesting that lead had leaked outof those zircons during the past quarter-billion years. And other zircon ages lookeddistinctly old, as if those zircons had crys-tallized earlier than the rest and had latergotten mixed in with them. By taking intoaccount how volcanic ash beds are stackedaround the rock layer that shows the ex-tinction, Bowring believes he can confi-dently select the reliable zircon ages anddiscard the rest.
Mundil set out to take this “picking andchoosing” out of uranium-lead dating. Overthe years, researchers had tried various pre-treatments to get rid of the parts of a zirconthat had lost lead. To prepare new samplesfrom southern China, Mundil and col-leagues adopted a technique recently devel-oped by James Mattinson of the Universityof California, Santa Barbara. They bakedthe southern China zircons at 850°C for 36hours and then leached them with hydroflu-oric acid under pressure at 220°C for 16hours, with the intention of removing theparts most weakened by radiation damage.
This rugged pretreatment narrows therange of zircon ages from a single ash bedfrom about 20 million years to a few millionyears, with no picking and choosing. Of the79 zircons dated in the P-T study reported
in this issue, the researchers dis-carded only three, all for beingobviously too old. Their age forthe P-T extinction is then 252.6 ±0.2 million years—about a mil-lion years older than Bowring’sage but coincident with a decade-old argon-argon radiometric agefor the Siberian Traps that Mundiland his colleagues—after makinga 2-million-year correction toit—prefer over Kamo’s uranium-lead age.
The new preprocessing tech-nique “is very promising,” saysDrew Coleman of the Universityof North Carolina, Chapel Hill.“It appears to be very fruitful.”Bowring agrees. “This is a stepin the right direction,” he says.“Mattinson’s annealing is the bigbreakthrough, though I have noidea why it works.” But Bowring
points to the later date that his group esti-mated for the P-T extinction in China andKamo’s group independently got for zirconand other minerals from the lavas of theSiberian Traps. Mundil hasn’t explainedhow subjective interpretation could haveproduced such a coincidence, he says.
What uranium-lead geochronologists neednow, all agree, is more cooperation. “They’vebeen competitive and secretive for decades,”says geochronologist Randall Parrish of theBritish Geological Survey in Keyworth, U.K.“There’s not enough cooperation amongworkers seeking out best practice, but we’regoing to hash out a lot of these issues in Oc-tober.” That’s when uranium-lead and argon-argon daters will gather near Boston underthe auspices of the new EARTHTIME pro-gram for a frank and open discussion of allthose little details that don’t make it into theliterature. –RICHARD A. KERR
In Mass Extinction, Timing Is All A new, apparently improved, way to date the greatest mass extinction points to a volcanic cause but fails to resolve geochronologists’ long-running differences
Geochemistry
Better for it. Hot acid has removed degraded parts of thiszircon that would have skewed its apparent age.
1706
Three years ago, the small number of lifescientists using the term “biosecurity”were talking about ways to keep diseasedcrops and livestock from crossing nation-al borders. Then came the fatal October2001 anthrax letter attacks against sever-al U.S. targets. In short order, thousandsof U.S. scientists were confronted withan avalanche of new and often unpopularrules designed to keep potentially dan-gerous pathogens and toxins away frombioterrorists. Researchers who breakthose rules could face significant crimi-nal penalties.
Despite these aggressive steps on thehome front, U.S. off icials readily ac-knowledged that unilateral action was in-sufficient and that the world needed toform a united front against increasinglysophisticated biotechnologies. But manynations were skeptical of the threat. Theyalso doubted the value of what criticscall “the guns, guards, and gates” ap-proach to biosecurity. The result, saysReynolds Salerno, a biosecurity expert atSandia National Laboratories in Al-buquerque, New Mexico, has been“tremendous confusion and concern inthe international life sciences communityabout biosecurity.”
That confusion may be giving way tocooperation, however, as an increasinglyglobal effort to def ine and implementbiosecurity is gaining speed. Nations aremoving to pass new biosecurity laws,while public health and security expertsare hammering out voluntary biosecurityguidelines and debating “codes of con-duct” for life scientists. Many countriesare thinking about looser rules for lessrisky agents than in the United States,which critics say has imposed a one-size-fits-all approach, and few are likely to re-quire the extensive criminal backgroundchecks carried out by U.S. agencies.
The new world order may not resemblethe U.S. model. But like it or not, life scien-tists worldwide are about to become muchmore familiar with the term biosecurity.
–DAVID MALAKOFF
BiosecurityGoes GlobalThe 2001 anthrax letters triggered astrong U.S. response. Now the rest of theworld is starting to take biosecuritymore seriously—but not necessarily byadopting the U.S. approach
B ioterrorism
Whose resolve? Last April,the United Nations SecurityCouncil adopted Resolution1540, which expresses “graveconcern” about bioterrorism
and directs U.N. members to enact tough controls on po-tential bioweapons. The resolution is intended to help closelegal loopholes in dozens of nations—including some withgrowing biotech industries—with laws that don’t cover allthe bases. “They are now obligated to build the legal frame-work needed for effective biosecurity,” says Barry Kellman,a law professor at DePaul University in Chicago, Illinois.Critics, however, see the measure as a U.S.-backed gambitto sidestep efforts to strengthen the Biological and ToxinWeapons Convention, which is in limbo until at least 2006.
Biocrime fighters. Interpol, the International Criminal Police Organization, has launched a 2-year effort to trainpolice in its 181-member countries on biosecurity andfighting bioterrorism. “You’d be amazed at how little theaverage police chief knows about the subject,” says BarryKellman of DePaul University, who is involved in the proj-ect, which is funded by the Alfred P. Sloan Foundation.One goal: to teach investigators how to avoid lumping legitimate researchers in with the biocriminals.
Spreading the word. U.K. officials are preparing to host aBioweapons Convention–related summit in October 2005 on“codes of conduct” for life scientists who work with poten-tially dangerous pathogens and biotechnologies. Althoughfew believe that such codes will deter evildoers, advocatessay they can play an important role in raising awareness ofbiosecurity. This winter, academic and industrial scientists willgather in Washington, D.C., to sign a pledge to help preventthe misuse of biological research—a theme also stressed in anew public relations campaign (left) by the InternationalCommittee of the Red Cross (www.icrc.org). Such efforts are“a way to encourage dialogue,” says Michael Moodie of the
Chemical and Biological Arms Control Institute, an organizer of the Washington meeting.In the meantime, the Federation of American Scientists and other groups are preparingbiosecurity course materials for undergraduate and graduate students.
Center of expertise. The United States andEurope are spending more than $90 millionannually to help Russia secure its sprawlingformer bioweapons complex and employ anestimated 6000 former bioweapons scien-tists. But efforts to attract investment fromforeign biotech and drug firms have hadmixed results, and some critics say moreneeds to be done to prevent ex-Sovietpathogens and weapons experts from leakinginto the black market. “Biosecurity is aboutlimiting the spread of expertise, too,” saysAmy Smithson, a nonproliferation specialistat the Center for Strategic and InternationalStudies in Washington, D.C.
CRE
DIT
S:(C
LOC
KW
ISE
FRO
M T
OP
LEFT
) IC
RC;P
.VIR
OT/
WO
RLD
HEA
LTH
ORG
AN
IZAT
ION
;ASS
OC
IATE
D P
RESS
;CU
H2A
ASS
OC
IATE
D P
RESS
;S.P
ARI
S/U
NIT
ED N
ATIO
NS
Lessons learned. The Republic of Georgia is on theverge of adopting biosecurity rules modeled on the U.S.approach—but with some important differences. Forinstance, the same agency will regulate both bio-medical and agricultural scientists; in the United Statesthat job is split between the Centers for Disease Con-trol and Prevention and the U.S. Department of Agricul-ture. “We’re telling people that our model is often farmore complicated than what they need,” says a U.S.State Department official who advises other govern-ments on biosecurity.
Asia alert. Asian Pacific leaderspledged last year to get toughon biosecurity—in part due tofears that their rapidly growingbiotech industries could attractregional terrorist groups alongwith investors. “Singapore viewsthis threat with grave concern,”Deputy Prime Minister Tan KengYam said at a biosecurity confer-ence held in the city-state earli-er this year. China, meanwhile,has ratcheted up export controlsand is examining both itsbiosafety and biosecurity rules inthe wake of the SARS epidemicand several lab accidents.
Self-help book. Early next year, the 192-member World Health Organization (WHO)plans to unveil its first-ever set of international biosecurity guidelines. The consensushow-to guide, currently in draft form, should help “clear up a lot of confusion … byclarifying best practices and minimum standards for keeping pathogens secure,” saysBrad Kay, a WHO biosafety expert in Lyon, France.
But implementing the voluntary standards is another story. Many poorer nations won’twant to divert precious public health funds to security, andWHO has meager resources to help out. It also isn’t clear whatwould happen to labs that don’t meet the standards. “WHOhas no mandate to become a global enforcer,” says Kay.
In the United States, meanwhile, a team of govern-ment and academic researchers is writing a new biosecu-rity chapter for the “bible” of lab safety, Biosafety in Microbiological and Biomedical Laboratories.
Building boom. Kazakhstan isthe first of several nations get-ting new, secure laboratoriesto store and study dangerouspathogens. The facilities arecourtesy of a U.S.-funded ef-fort to reduce the bioterrorthreat in the former Soviet Union. Construction of the new Human HealthCentral Reference Lab and Repository in Almaty is set to begin in mid-2005,with Uzbekistan and Georgia next on the list. Meanwhile, talks are under wayon long-term strategies for consolidating the 500 or more culture collectionsaround the world that stock dangerous pathogens, with a goal of fewer, moresecure facilities.
N E W S F O C U S
Powerful target validation – we’ve alreadydone some of the work for you…367,000 human qRT-PCR datapoints
1,700 human gene expression profiles216 human tissues per profile
72 human tissue types15 human gene families
1 Pharmagene TargetEvaluatorTM
Pharmagene TE Core™
and it’s now more accessible…Pharmagene TE CoreTM speeds up the process of target validation andgives you more confidence in your target selection. It provides a toolfor the rapid stratification of gene targets and can also indicatepotential safety issues in your pre-clinical compounds, allowing youto highlight and address issues early on.
Pharmagene TE CoreTM is affordable and immediately available.Search 1,700 human gene targets at www.pharmagene.com/TECorefor your targets today and benefit from new ‘sliding scale’ prices.
Pharmagene TE CoreTM is the logical way to enhance your drugdiscovery process - contact us today.
Telephone:+44 (0)1763 211 600Facsimile: +44 (0)1763 211 555Email: [email protected]/TECore
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1709
CRE
DIT
S (T
OP
TO B
OTT
OM
):O
XFO
RD A
RCH
AEO
LOG
Y;N
.T.L
INFO
RD,A
RCH
AEO
L.PR
OSP
ECT.
11,
1–13
(20
04);
IN D
EFEN
SE O
F A
NIM
ALS
Edited by Constance Holden
RANDOM SAMPLES
Defying DarwinPromoters of intelligent design, the “scientific” wing of creationism, are gloat-ing over a tactical victory this summer:the appearance of a critique of Darwinianevolution in a peer-reviewed biology journal. But the current editors say thejournal shouldn’t have published it.
The piece by Stephen Meyer, directorof the Discovery Institute’s Center for Science and Culture in Seattle,Washington, appeared last month inthe Proceedings of the Biological Societyof Washington, a small journal publishedby the Smithsonian Institution’s Museumof Natural History. The article was accept-ed by then-editor Richard Sternberg, whodoes systematics research at the NationalInstitutes of Health’s GenBank. Sternberg isone of the signatories of “A Scientific Dissent from Darwinism,” a statement circulated by the Discovery Institute.
The article has ruffled feathers at thejournal. Its current editor, ornithologistRichard Banks, says Sternberg deviatedfrom the journal’s practice of assigningevery submission to an associate editor.The society issued a statement callingthe Meyer paper “a significant departurefrom the [journal’s] nearly purely taxo-nomic content” and says the officers and
editors “would have deemed this paperinappropriate for publication” if they’dknown about it in advance.
Sternberg, who calls himself an advo-cate of “process structuralism,” says the
paper “was not outside thejournal’s scope” and
was reviewed by three biologists. “Meyerset forth a reasoned view about the basis oftaxa” which deserved airing despite being“politically incorrect,” he says.The DiscoveryInstitute has been making hay over theincident. “Darwinists try to thwart intellec-tual freedom,” crows its Web site.
MagneticMemoriesSkeletons often dis-solve when buriedin acidic soils. Nowan archaeologisthas shown that he can detect long-decayed remains bymeasuring the faintmagnetic signalformed by soil microbes that en-hance the magnet-ism of iron oxidesfrom hemoglobin and other sources. Thisimage, published in the current issue ofArchaeological Prospection by archaeologi-cal geophysicist Neil T. Linford of EnglishHeritage in Portsmouth, U.K., shows themagnetic signal from soil covering aroughly 1200-year-old Anglo-Saxonskeleton from Suffolk.
Viking Burial SiteArchaeologists are thrilled by the discovery of
the first Viking graveyard uncovered in England,which they hope will shed light on a period with a
notoriously scant record.The famously fierce Vikings of Scandinavia surged up
English shores in the 8th century and dominated until the Norman conquest in 1066, leaving a lasting legacy in
terms of genes, language, and culture. But unlike their predecessors, the Romans,the Vikings rarely built permanent remains such as stone roads or buildings.
The find was made in March by an amateur, Peter Adams, wielding a metal detector on farmland in Cumbria, northwestern England. Archaeologists uncoveredsix graves with Viking objects including weapons, spurs, and jewelry that seem todate to the early 10th century. Little of the skeletons remain due to the acidic soil,but the objects suggest that the graves contained four men and two women. “Tofind just one grave is great,” says excavation director Alan Lupton of the firm Oxford Archaeology North, who directed the 8-week excavation. “To find six ismind-blowing.” University of Oxford archaeologist David Griffiths says there areViking grave sites in Scotland and Ireland, but they were excavated in the 19th century under less than scientific conditions.
The graves show features of both pagan and Christian burial practices thatcould yield information about how Vikings made the transition from paganism toChristianity, says Lupton.
More Chimp ChargesThe government facility in Alamogordo, New Mexico, thathouses the former Coulston chimps faces new animal-
welfare accusations—this time over the 2002 deaths of twosick chimps and the near-death of a third. On 7 September theOtero County district attorney filed animal-cruelty charges
against Charles River Laboratories, which runs the facility forthe National Institutes of Health (NIH), and the facility’s di-rector, veterinarian Rick Lee.
The animals are largely the offspring of those used in early space-flight experiments. Many were turned over in 1998 to the Coulston Foundation in Alam-ogordo. But in 2001, following accusations of negligence and cruelty, NIH putthem in the care of Charles River (Science, 27 September 2002, p. 2191).
In Defense of Animals, a California-based group that has been critical of the fa-cility, claims that care has still not improved. Based on reports from whistleblow-ers, the district attorney brought charges relating to the deaths or near-death ofthree severely sick or injured chimps, Rex, Ashley, and Topsy, who had been leftovernight without medical care. Charles River issued a statement saying that theyalways provided “immediate and appropriate medical attention” to the animals inquestion. NIH said in a statement that the facility has passed inspection for prop-er accreditation but that the agency will “continue to review the issues.”
Viking brooch.
Ill-fated Ashley.
1-800-52-NIKON • In Canada, 1-866-99-NIKON • www.nikonusa.com
There’s never been a more optically advanced
automated research microscope system thanNikon’s new Eclipse i-series 90i. Combinedwith the Nikon Digital Sight Camera andexclusive ACT-2U software, the 90i delivers a completely integrated, totally optimizeddigital microscopy system that seamlesslymasters the most demanding applications. The result? Amazing imaging performancethrough efficient, effortless operation.
The optical system and automation features of the 90i were entirely re-engineered, toprovide the highest quality digital imagingperformance available. The system isequipped with all-new, designed-for-digitalCFI Plan Apo VC objectives,delivering incredibly crisp, cleanand true-to-life images. Combinethis with the 90i’s exclusive motorized digitalhead, proprietary “fly-eye” lens array, and integrated epi-fluorescence attachment,and you have a digital microscope systemready to take on the broadest range ofapplications. With performance this inspired,the 90i lets you spend less time adjustingyour microscope and more time conductingyour research.
To learn more, visit www.nikon-i.comor call 1-800-52-NIKON.
Introducing Nikon’s Eclipse 90idigital microscope:Creating new standardsin optics, automation,and pure performance.
© 2004 Nikon Instruments Inc.
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1711
Rights warrior. Nguyen DanQue, a Vietnamese endocri-nologist currently under ar-rest in his home country, hasreceived the 2004 Heinz R.Pagels Human Rights of Sci-entists Award from the New
York Academy of Sciences.The 61-year-old doctor hasspent 18 of the last 26 yearsin prison as a consequenceof his efforts to promote human rights and democracyin Vietnam.
After graduating fromSaigon Medical School in1966, Nguyen practiced med-
icine in Europe on a scholar-ship from the World HealthOrganization but soon re-turned to Vietnam to providefree medical care for the poor.He became an outspoken crit-ic of the government’s healthcare policy and a champion offreedom of expression in thelate 1970s.
Nguyen has been held in-communicado since his mostrecent arrest in March 2003.His brother, Quan Nguyen, aninternist at Fairfax Hospital inAnnandale, Virginia, says hisbrother does not know aboutthe award but “would be veryhonored to receive it.”
You go, girl. Women scientistsreceived 60% of the NationalScience Foundation (NSF)–backed early career awardsannounced last week by theWhite House. That’s a surpris-ing outcome, given that thepool of young scientists fromwhich NSF picks its winners isroughly 3-to-1 male. “The unmistakable message is thatwomen have arrived,”says NSF’s acting director,Arden Bement.
Maybe at NSF, butapparently not at the
other seven agencies thatparticipated in the 2003 Presidential Early CareerAwards for Scientists and
Engineers (PECASE). NSF’scontingent of 12 women (outof 20 winners) is twice thecombined total of women inthe rest of the PECASE classof 57. The National Institutesof Health’s class of 2003, bycomparison, contains 10 menand two women.
Herpetology honor. Universityof Wales biologist Simon Creerhas won the Joseph B. SlowinskiAward for Excellence in SnakeSystematics from the Centerfor North American Herpetology.The award was created to honorSlowinski, a curator at the California Academy of Sciencesin San Francisco, who died af-ter being bitten by a venomouskrait in Myanmar on 11 Sep-tember 2001 (Science, 5 October 2001, p. 45). ThomasWilcox of the University ofTexas, Austin, won the firstaward last year.
A W A R D S
CRE
DIT
S (T
OP
TO B
OTT
OM
):A
AA
S;Q
UA
N N
GU
YEN
;ESP
IRANDOM SAMPLES
PEOPLEEdited by Yudhijit Bhattacharjee
Got any tips for this page? [email protected]
D E A T H S
Popularizer par excellence. Gerald Piel, a pioneer of modernscience journalism and formerpublisher of Scientific American,died on 5 September in Queens,New York. He was 89.
A history major at HarvardUniversity, Piel was science editorat Life in the 1940s before buyingScientific American with somefriends in 1947. He introduced theidea of having scientists write pop-ular accounts of their research,which helped boost its readershipover the years. Piel remained an in-fluential voice after stepping downas publisher in 1984, serving aspresident of AAAS (publisher ofScience) in 1986 and writing bookssuch as The Age of Science: WhatScientists Learned in the TwentiethCentury (2001).
“He was a landmark figure in journalistic letters, and he di-rectly promoted the growth of science as much as any oneperson could,” Scientific American noted in an obituary earlierthis month.
Continental vision. A French nuclearphysicist–turned–policy wonk has been named the firstdirector of the newly created European Space Policy Institute (ESPI) in Vienna, Austria. Serge Plattard takesup the reins of an institute, founded last November bythe European Space Agency and the Austrian SpaceAgency (ASA), that will try to draw up a long-termframework for European space research. “We have lotsof programs but no vision,” he says.
Plattard, 57, anticipates having a staff of up to adozen analysts and an annual budget of $1.8 million.“I know how to manage international and multi-disciplinary teams,” he says, “and how to attract non-standard funding.”
Plattard wants ESPI to be very independent and produce studies that can be instantlyused by decision-makers. He’s certainly up to the task, according to ASA’s Michel Jakob,who says Plattard “can talk on the level of ministers and scientists. He can speak witheverybody and be taken seriously.”
J O B S
Wow!
© 2004 Gene Logic Inc.
What you may know aboutyour gene target now.
• Published literature
• Some genomic data
• Limited pathway data
What you will know withthe new ASCENTA™ System.
• Your target’s comprehensive gene expressionprofile across more than 8,000 normal anddisease tissues
• If your target is uniquely or broadly expressed
• How your target is regulated in human disease—inflammation, oncology, CVS, CNS, metabolic
• Co-expression with other genes—both up anddown regulated
• More
Everyone who sees what two clicks in theASCENTA™ System reveals about gene expressionhas the same reaction:
“Wow!”
You will too.The ASCENTA™ System is anaccessible new way to zero in on your gene ofinterest. It quickly gives you reliable and relevant,microarray-based data to confidently prioritizeyour drug targets.
What’s more, you don’t have to be a bioinformaticswhiz to use the ASCENTA™ System. And you don’thave to be Big Pharma to afford it.
Go to www.genelogic.com/solutions/ascenta foran introduction today.Then call 1-800-GENELOGIC
to arrange for a demonstration and see what geneexpression can show you.
The ASCENTA™ System. It’s fast, easy to use, andsurprisingly affordable.Get the full picture
in just two clicks.
www.genelogic.com/solutions/ascenta
www.sciencedigital.org/subscribeFor just US$130, you can join AAAS TODAY and
start receiving Science Digital Edition immediately!
www.sciencedigital.org/subscribeFor just US$130, you can join AAAS TODAY and
start receiving Science Digital Edition immediately!
Hollywood, ClimateChange, and the Public
IN HIS EDITORIAL “CLIMATE CHANGE ANDclimate science” (11 June, p. 1565), DonaldKennedy argues that although there is broadscientific consensus over the anthropogenicorigin and growing seriousness of currentclimate change, public attention has insteadfocused on areas of scientific disagreementand on extreme but unlikely future scenarios.Against this background, there has beenconsiderable debate about the potentialimpact on public opinion of the disaster filmThe Day After Tomorrow, in which globalwarming triggers a sudden shutdown of theNorthern Atlantic Conveyor, bringing about anew ice age in a matter of days. Althoughsome (1) argue that the film is likely tosucceed in its makers’ aim (2) of raisingconsciousness about climate change, others(3, 4) suggest that by portraying dramatic butexceptionally unlikely events (5, 6), it willinstead reduce public understanding.
To shed light on this controversy, wecollected data on 200 adults’ levels ofconcern and knowledge about climatechange, either on their way into (N =95) or after seeing (N = 105) the film.
Simple questionnaire surveys were conductedat four cinemas in southeastern England(Epsom, Putney, Sutton, and Wimbledon) inJune and July 2004. Besides backgroundsocioeconomic data (age, sex, educationallevel, income, parental status, and environ-mental charity membership), questionsfocused on concern (measured as how muchout of a hypothetical £1000 people wanted togive to climate mitigation versus four othergood causes), on how many emission-reducing actions people already took orplanned to take, and on knowledge ofpredicted temperature changes and theirlikely consequences (7, 8). We assessedconcern before asking questions that revealedthat the survey focused on climate change.Here we examine the impact of the film bytesting for differences in scores betweenarriving and departing filmgoers.
Watching The Day After Tomorrow didindeed raise levels of concern: Those ques-tioned after seeing the film allocated almost50% more of their hypothetical £1000 toclimate mitigation than those interviewed onarrival [means ± SE of £180.13 ± £15.20versus £122.25 ± £13.20; t184 = −2.67, P <0.01 (9)]. Moreover, this exit-entry differenceremained significant after controlling for thepositive effect of parenthood (10). There wasno difference in how many kinds of emission-reducing actions (such as using public trans-port or low-energy bulbs) that our exit andentry sample already undertook (1.71 ± 0.10versus 1.80 ± 0.10; t190 = 1.15, NS), but the
film also had no detectable effect on thenumber they planned to undertake in future(2.56 ± 0.11 versus 2.64 ± 0.11; t191 = 0.71,NS). There was no change, after seeing thefilm, in people’s score for knowledge of likely21st-century temperature change (2.60 ± 0.07versus 2.62 ± 0.06; t171 = 0.26, NS), despitetwice as many exiting filmgoers suggesting itwill become colder. However, when askedwhich specific effects of climate change arepredicted (7, 8) for the UK by 2100, those whohad seen The Day After Tomorrow had lessrealistic expectations than those interviewedbeforehand (11).
Overall, the data thus suggest thatseeing an entertaining if exaggerated illus-tration of the possible effects of climatechange succeeds, in just 125 minutes, inraising public concern—but at the price ofreducing public understanding. It would beinteresting to see if these divergent effectshold in other countries, and which, ifeither, persists over time. More generally,our findings confirm that intense dramati-zations have real potential to shift publicopinion. However, the question remainswhether such portrayals can be made moreaccurate (and thereby less confusing)without losing their popular appeal.
ANDREW BALMFORD,1,2 ANDREA MANICA,1*LESLEY AIREY,1 LINDA BIRKIN,1 AMY OLIVER,1
JUDITH SCHLEICHER1
1Department of Zoology, University of Cambridge,Downing Street, Cambridge CB2 3EJ, UK. 2PercyFitzPatrick Institute of African Ornithology,University of Cape Town, Private Bag, Rondebosch7701, Cape Town, South Africa.*To whom correspondence should be addressed. E-mail: [email protected]
References and Notes1. Nature 429, 1 (2004).2. The Day After Tomorrow Web site, www.thedayafter-
tomorrow.com, accessed 12 July 2004.3. P. J. Michaels, USA Today, 25 May 2004, p. A21.4. F. Pearce, “Scientists stirred to ridicule ice age claims,”
NewScientist.com, 12 July 2004 (available at www.newscientist.com/news/news.jsp?id=ns99994888).
5. W. S. Broecker, Science 304, 388 (2004).6. A. J.Weaver, C. Hillaire-Marcel, Science 304, 400 (2004).7. J. T. Houghton et al., Eds., Climate Change 2001: The
Scientific Basis (Cambridge Univ. Press, Cambridge,2001).
8. UK Climate Impacts Programme, www.ukcip.org.uk,accessed 12 July 2004.
9. All t tests used arc-sine square-root-transformed scores,expressed as percentages of the maximum possible.
10. A minimal Generalized Linear Model (GLM) withquasi-binomial error structure gave F2,197 = 7.19, P =0.001, with P < 0.05 for both terms; no significantinteractions.
11. Mean scores (out of 6): 3.06 ± 0.13 versus 3.48 ± 0.13;t179= 2.57, P = 0.01; with the effect remaining significantin a GLM controlling for sex and the positive effects ofincome and charity membership: F4,195 = 8.43, P < 0.001,with P < 0.05 for all four terms;no significant interactions.
12. Readers interested in replicating this survey shouldcontact the corresponding author for a copy.
Impact of watching The Day After Tomorrow on people’s concern and knowledge about climatechange. Concern is measured as how much out of a hypothetical £1000 people wanted to give to climatemitigation versus four other good causes (social or medical charities, overseas aid, or animal welfare).Knowledge is scored as how many out of six possible effects (increased winter flooding, house subsidence,late frosts, earlier flowering, lawn-mowing in winter, and the Thames freezing solid) respondents correctlyidentified (8) have or have not been predicted for the UK by 2100.The histograms show means ± SE.Thephoto shows a scene from The Day After Tomorrow, in which a tidal wave hits New York City.
Letters to the EditorLetters (~300 words) discuss material publishedin Science in the previous 6 months or issuesof general interest. They can be submittedthrough the Web (www.submit2science.org)or by regular mail (1200 New York Ave., NW,Washington, DC 20005, USA). Letters are notacknowledged upon receipt, nor are authorsgenerally consulted before publication.Whether published in full or in part, letters aresubject to editing for clarity and space.
LETTERS
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1713
CRE
DIT
S:(P
HO
TO)
CO
URT
ESY
OF
20TH
CEN
TURY
FO
X/B
URE
AU
L.A
.CO
LLEC
TIO
NS/
CO
RBIS
250
200
150
100
50
0
4
3
2
1
0Entry
Mo
ney
for
clim
ate
mit
igat
ion
(£)
Kn
ow
led
ge
of
UK
eff
ects
Exit Entry Exit
Questions and Answers.
Some particularly gifted children might be able to
make quantum leaps in their education and find
science a relatively easy subject to comprehend.
Others may need a little more help and encouragement
at an early age. Helping develop that interest and
provide the learning tools necessary is something we
at AAAS care passionately about. It’s a big part of the
very reason we exist.
Our educational programs provide after-school
activities such as the Kinetic City web-based science
adventure game, based on the Peabody Award
winning Kinetic City radio show; Science Netlinks,
with over 400 science lessons available on the
Internet; and Project 2061, which provides teaching
benchmarks to foster an improved understanding of
science and technology in K-12 classrooms.
AAAS has been helping to answer the questions of
science and scientists since 1848, and today is the
world’s largest multidisciplinary, nonprofit membership
association for science related professionals. We work
hard at advancing science and serving society – by
supporting improved science education, sound science
policy, and international cooperation.
So, if your question is how do I become a member,
here’s the answer. Simply go to our website at
www.aaas.org/join, or in the U.S. call 202 326 6417,
or internationally call +44 (0) 1223 326 515.
Join AAAS today and you’ll discover the answers
are all on the inside.
www.aaas.org/join
Who’s cultivating tomorrow’s
scientific geniuses?
L E T T E R S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org
Evidence for Taming of Cats
THE RECENT BREVIA CONCERNING EVIDENCE OFearly taming of cats (“Early taming of the catin Cyprus,” J.-D. Vigne et al., 9 Apr., p. 259)contains some statements that I feel should bescientifically tempered. Vigne et al. state “Thejoint burial could also imply a strong associa-tion between two individuals, a human and acat… The Cyprus burial thus likely representsearly evidence for the taming of cats.”
The Cyprus find is at best evidence of arelationship between an admired human beingand a possibly commensal species of wildanimal, Felis sylvestris. Students of felinesystematics have long identified the Africanwild cat (F. silvestris) as the sister group to thedomestic cat (1–3). However, in the absenceof any artifacts of domestication at the Cyprussite (collar, clothing, cage, evidence of castra-tion of male, jewelry on the cat, and so forth),the felid in question must be considered a wildcommensal species.
I think it is fair to say that the first status orstage of this process was that of a commensalvariety of the wild cat. It is further reasonableto assume that the wild cat was welcomed inthe vicinity of early humans, as it helpedcontrol a less acceptable commensal animal,the rodent. The transition from the Africanwild cat to a truly domesticated feline wouldhave involved living and breeding as a tamemember of a human dwelling. As a paleontol-ogist and a veterinarian, I suggest we seekmore hard evidence before using the term“tame” or “domesticated.”
TOM ROTHWELL
Division of Paleontology, American Museum ofNatural History, Central Park West at 79th Street,New York, NY 10024, USA.
References1. J. Clutton-Brock, A Natural History of Domestic
Mammals (Harvard Univ. Press, Cambridge, MA, ed. 2,1999), pp. 133–140.
2. M. F. Essop, N. Mda, J. Flamand, E. H. Harley, S. Afr. J.Sci. 27, 71 (1997).
3. R. I. Pocock, Proc. Zool. Soc. London 1907, 143 (1907).
ResponseWE THANK ROTHWELL FOR HIS REMARKS. IT ISimportant to remember that, as in paleon-tology, archaeological results can never beconsidered as certainties, but only as prob-abilities. However, we continue to suggestthat “[t]he Cyprus burial… likely repre-sents early evidence for the taming of cats”and not merely a manifestation of acommensal status of a wild species.
The cat is one of the seven species of largemammals, among the several tens of wildspecies once present in Western Asia, thatwere introduced voluntarily onto the island ofCyprus at the very beginning of the Neolithic,across an 80-km-wide sea channel. Five of the
other introduced species (dog, sheep, goat,pig, and cattle) subsequently became the maindomesticated animals of the Middle East. Theprobability that the cat could have travelledacross the sea on its own seems to us to beextremely small.
During the 9th and the beginning of the 8thmillennia B.C.), the house mouse and the fox(1) share with the cat the peculiarity of havingbeen both commensal and introduced ontoCyprus. Like the cat, the fox must have beenvoluntarily introduced by humans; however,unlike the cat, the fox did not become adomestic species in the following centuries.Although much more frequently recovered inthe Cyprus Neolithic sites than those of thecat, its bone remains have never been found ina burial or in any symbolic situation, but onlyas food refuse.
As we argue in our Brevia, “[t]he burialof a complete cat… emphasizes the animalas an individual.” In this Middle Eastcomplex of cultures of the Pre-Potteryneolithic, when wild animal species appearin any kind of cultic contexts, they aresymbolically represented by heads, horn-cores, antlers, jaws, scapula, and so forth,very rarely as a complete individual (2, 3);only human beings and some domesticanimal with special status such as dogs in theNatoufian culture or some sheep in theKhirokitia culture (4) are buried as completebodies.
Rothwell seems to base his arguments onan old concept of the genus Felis. Accordingto the most recent phylogenetic works (5),what he calls “the African wild cat” (i.e., thelybica subspecies of F. silvestris) also includesthe wild cats of the Near East. Consequently,the proximity between the domestic cat andthe African wild cat does not mean that theancestor of the domestic cat is lived in Africa.
Furthermore, the majority of moderndomestic animals (and probably in Neolithictimes) have no “collar, clothing, cage, …jewelry” and are not castrated. This kind ofevidence is of little use in detecting earlydomestication. Among the few criteria that arevalidated by most palaeoanthropologists (6)are the occurrence of a taxon previouslyunrecorded in a region and incorporation intoa society’s symbolic system. These are the twomain arguments that we use for suggestingthat the Cyprus cat was tamed.
Finally, Rothwell is correct when hewrites “The transition… to a truly domesti-cated feline would have involved living andbreeding as a tame member of a humandwelling.” But it seems to us and tonumerous other archaeologists that thepurposeful introduction of the cat onto theisland at a time when seafaring was prob-ably still in existence and its exceptionalpresence in the environment of the burialsuggest that at least some cats did live in
such conditions in Cyprus during thepreceramic Neolithic period.
J.-D. VIGNE1 AND J. GUILAINE2,3
1CNRS–Muséum national d’Histoire naturelle,Department of Ecology and Biodiversity Manage-ment, UMR 5197, C.P. 56, F-75231 Paris Cedex 5,France. 2CNRS-EHESS, Centre d’Anthropologie, 39allées Jules Guesde, F-31000 Toulouse, France.3Collège de France,Chaire des Civilisations de l’Europeau Néolithique et à l’Âge du Bronze, 11, Place M.Berthelot, F-75005 Paris, France.
References1. J.-D.Vigne, J. Guilaine, Anthropozoologica 39, 249 (2004).2. D. Helmer, L. Gourichon, D. Stordeur, Anthro-
pozoologica 39, 143 (2004).3. L. K. Horwitz, N. Goring-Morris, Anthropozoologica
39, 165 (2004).4. P. Dikaios, Khirokitia (Monograph of the Department
of Antiquities of the Government of Cyprus 1, OxfordUniv. Press, Oxford, 1953).
5. E. Randi, M. Pierpaoli, M. Beaumont, B. Ragni, A. Sforzi,Mol. Biol. Evol. 18, 1679 (2001).
6. S. J. M. Davis, The Archaeology of Animals (Batsford,London, 1987).
Figuring Out WhatWorks in Education
IN HIS ARTICLE “MEAGER EVALUATIONS MAKE IThard to find out what works,” J. Merviswrites about the difficulties of assessingeducation research (News of the Week, 11June, p. 1583). The only way to establish acurriculum’s effectiveness is throughrandomized, control trials similar to thoseused in clinical research. The idea ofcontrolled trials in evaluation is certainlynot new, and I learned about them in the1970s while studying for a Ph.D. in educa-tion. Unfortunately, interest in educationalprogram evaluation has remained theoreticalin schools. In fact, in frustration, I left educa-tion studies and moved to academic medi-cine, where effectiveness research andsystematic literature reviews to find bestpractices are the norm (1). I take issue withthe idea that controlled studies are difficult todo because “[i]t’s hard to exclude people from
a program that they think is working.”Controlled studies are based on rational inclu-sion and exclusion criteria and aim to demon-strate under which circumstances and forwhom programs work best (if they work atall). Also, although it is true that measuringhuman behavior is “hard to quantify,” thatdoes not mean we cannot do it reasonablywell. In academic medicine, we have foundways to measure concepts like satisfaction,decision-making, and quality of life. Surely,with effort, educational evaluators can iden-tify valid measures of educational outcomes.
One possible explanation for the poorstudies we find in education is that evalua-tions cost as much as program development.The best ones are conducted by multidiscipli-nary teams of educational researchers andexperts in design, measurement, and dataanalysis. Educational programs are always ina cash crisis. Yet the consequences of imple-menting programs of unknown quality arelikely to be even more costly in terms of theeducational opportunity they waste.
ARLENE FINK
Center for Research, Education & Quality inHealth, 1562 Casale Road, Pacific Palisades, CA90272, USA. E-mail: [email protected]
Reference1. See, for example, B. Stein et al., JAMA 290, 603 (2003).
CORRECTIONS AND CLARIFICATIONS
News of the Week: “Patient advocate named co-inventor on patent for the PXE disease gene” by E.Marshall (27 Aug., p. 1226). The article incorrectlystated that Charles Boyd’s group at the Universityof Hawaii was first in a four-way race to report thegene 4 years ago. Although the four groupspublished within a few weeks, and Boyd’s groupholds the patent, the first report in print was byJouni Uitto and colleagues at the ThomasJefferson University in Philadelphia.
Random Samples: “Side effect” (6 Aug., p. 775).The item should have noted that University ofPittsburgh geneticist Robert Ferrell resigned aschair of his department because he is undergoingtreatment for recurring non-Hodgkins lymphoma.
L E T T E R S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004
TECHNICAL COMMENT ABSTRACTS
COMMENT ON “The Early Evolution of the Tetrapod Humerus”P. E. Ahlberg
Shubin et al. (Reports, 2 April 2004, p. 90) claimed that specimen GSM 104536 from Scat Craig, Scotland—described as the earliest known tetrapod humerus—entirely lacks tetrapod characteristics. This unsupportedassertion contradicts the published descriptions and comparative analyses of the specimen, and thus misrepre-sents this potentially important fossil.Full text at www.sciencemag.org/cgi/content/full/305/5691/1715c
RESPONSE TO COMMENT ON “The Early Evolution of the Tetrapod Humerus”Michael I. Coates, Neil H. Shubin, Edward B. Daeschler
Virtually all of the features used to associate GSM 104536 with tetrapod humeri are difficult to assess eitherbecause of preservation or differences between tetrapods and their fish relatives. This leaves two alternatives:Either the bone is not a tetrapod humerus or it represents forms far beyond the known range of early humeraldiversity. In the absence of more complete material, this bone remains enigmatic.Full text at www.sciencemag.org/cgi/content/full/305/5691/1715d
1716
Twentieth century economics has inlarge measure been detached from theenvironmental sciences. Judging by the
profession’s writings, we economists see na-ture at best as a backdrop from which re-sources can be considered in isolation; we al-so imagine most natural processes to be lin-
ear. Macroeconomicforecasts routinely ex-clude environmentalresources. Accountingfor nature, if it comesinto the calculus at all,is an afterthought tothe real business of“doing economics.”
One can argue thatthis practice has giv-en rise to a puzzling
cultural phenomenon: One group of re-searchers (usually natural scientists) sees inhumanity’s current use of nature’s servicessymptoms of a deep malaise, even whileanother group (usually economists) docu-ments the fact that people today are on av-erage better off in many ways than they hadever been and wonders why the gloom.
Underlying the intellectual tensions arethe conflicting intuitions that have arisenfrom different empirical per-spectives on whether the char-acter of contemporary econom-ic development, both in the poorworld and in industrializedcountries, is sustainable. On theone hand, if we look at specificresources and services (such asfresh water, a wide variety ofecosystem services, and the at-mosphere as a carbon sink),there is convincing evidence of-fered by earth scientists thatcontinued growth in the rates atwhich they are utilized is unsus-tainable. On the other hand, ifwe study historical trends in theprices of marketed resources(minerals and ores, for example) or therecorded increases in the conventionallymeasured indices of economic progress [suchas per capita gross national product (GNP)and the United Nations’ human development
index] in large numbers of countries, envi-ronmental and resource scarcities would notappear to have bitten yet.
Over the past few years, there has arisen asmall but professional literature that recon-ciles the conflicting intuitions. It does so byestablishing that, roughly speaking, sustain-able development involves the maintenanceof wealth, where the required measure ofwealth includes not only manufactured capi-tal (buildings and machinery) and humancapital (knowledge, skills, and health) but al-so natural capital (ecosystems). This litera-ture has identified the many circumstances inwhich a nation’s GNP per capita would in-crease over a period of time and its human de-velopment index improve, even while itswealth per capita declines. Evidence suggeststhat South Asian countries have experiencedthis pattern of economic change during thepast three decades, while sub-Saharan Africahas enjoyed an improving human develop-ment index despite suffering declines in GNPper capita and wealth per capita (1, 2). Inbroad terms, the circumstances of such expe-rience involve growing markets in certainclasses of goods and services (such as petro-leum products and transportation), concomi-tant with an absence of markets and collec-
tive policies for environmentalgoods and services. Moreover,global environmental problemsoften percolate down to createadditional stresses on the localresource bases of the world’spoorest people. The overallpoint is that when a commodityis unpriced, there is no incentiveto economize on its use.
In Red Sky at Morning,James Gustave Speth takes uson a guided tour of those glob-al (and largely interconnected)environmental problems thatare recognized by experts todayto be in the most urgent need ofattention. Speth, the distin-
guished dean of the School of Forestry andEnvironmental Studies at Yale University,marshals facts and figures in measuredtones. Refreshingly, he makes use of find-ings from both the social and earth sciencesto sketch some of the processes that charac-terize human-nature interactions. This per-mits him to explore fundamental explana-tions underlying environmental degradation.
For example, he recognizes that the morethan fourfold increase in human numbersduring the 20th century has been a proxi-mate cause of environmental degradation, sohe identifies several societal features re-sponsible for that increase. There is no hys-teria here, nor any attempt at cowering thereader with statistics: the style is that of akindly uncle rebuking his many nieces andnephews for the errors of their ways.
As would be expected of someone whopreviously administered the United NationsDevelopment Programme, Speth is engagednot only in reporting global environmentaldegradation but also in identifying institu-tional reforms that are necessary if we are tosuccessfully address the problem. In a far-reaching trio of chapters toward the book’send, he argues for the establishment of a newinternational organization that would act onbehalf of the environment in much the waythe World Trade Organization acts on behalfof a rational trading order. It was only whenI came to those concluding chapters that I re-alized that the earlier sections of the bookwere intended as a sort of intellectual prel-ude: Speth’s proposal for a new organizationappears as a logical necessity, borne out ofhumanity’s experience in dealing with na-ture. Red Sky at Morning is a most readableand altogether fine book. I can only hope itbecomes a most influential one.
References1. P. Dasgupta, Human Well-Being and the Natural
Environment (Oxford Univ. Press, Oxford, 2001).2. K. J. Arrow et al., J. Econ. Perspect. 18, 147 (Summer,
2004).
A N T H R O P O L O G Y
Culture andCommerce in aSeafood Bazaar
Stephen Gudeman
Bronislaw Malinowski launched modernethnography in the early 20th centurywith his study of gift exchange in the
Trobriand Islands of the South Pacific. Heshowed how reciprocity—the give and takeof things and services—provided the glue forsocial life and reflected the many strands ofTrobriand culture. Late in life, Malinowskiturned to the study of a market in Mexico, asif it might be the counterpart to reciprocity inmaking the economy and refracting parts of
CRE
DIT
:RO
GER
RES
SMEY
ER/C
ORB
IS
The reviewer is in the Faculty of Economics, Universityof Cambridge, Sidgwick Avenue, Cambridge, CB3 9DD,UK. E-mail: [email protected]
E N V I R O N M E N T
How Best to Face the Coming StormPartha Dasgupta
Red Sky at MorningAmerica and the
Crisis of theGlobal EnvironmentJames Gustave Speth
Yale University Press, NewHaven, CT, 2004. 317 pp.$24, £15.99, €25.60.ISBN 0-300-10232-1.
BOOKS et al.
The reviewer is in the Department of Anthropology,University of Minnesota, 395 Hubert H. HumphreyCenter, 301 19th Avenue South, Minneapolis, MN55455, USA. E-mail: [email protected]
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org
1717
culture. Since Malinowski, ethnographiesand studies of reciprocity have flourished,but the world has changed. Can today’santhropologists help us understand con-temporary economies and markets?Given the impact of postmodernist theo-ry, can they even claim that ethnographiesrepresent what a people do and think?
Tsukiji, Thomas Bestor’s study of theTokyo market that is the world’s largest mar-ketplace for fresh and frozen seafood, con-vincingly returns us to the ethnographic tradi-tion. At the Tsukiji market in 1966, nearly 6billion dollars of seafood changed hands, avolume of trade that dwarfs that of all otherfish markets. Bestor, a professor of anthropol-ogy at Harvard University, began his researchin 1989 and continued visiting the market forten years. With his intimate knowledge ofTsukiji, he provides the reader with anethnography filled with descriptions, “facts,”stories, verbal pictures, and a feeling for thesounds and tastes of the place and culture.
The study revolves about the theme thatTsukiji trade is embedded in the relation-ships, beliefs, and values of Japanese life.
The idea of embed-dedness is not new,but Bestor uses it toadvantage and dis-plays its power. Forexample, from theperspective of aneconomist, Tsukiji isa “spot market” inwhich goods are ex-changed betweenanonymous actors forshort-term advantageand profit maximi-zation. In contrast,Bestor demonstrates
how Japanese social patterns enable andconstrain the competitive trade. For Bestor,the notion of embeddedness has a verybroad reach.
The Tokyo fish market probably datesto the 1500s, although the current market-place was constructed only in the 1920s.Bestor shows how its history, changingcustoms, and physical layout all affectprice-setting. In addition, the seafood soldat Tsukiji comes from local fishermen andfrom all parts of the world, so pricing re-flects global trends. Because demand is lo-cal to Tokyo, Bestor also explains howJapanese tastes and habits drive the marketyet are influenced by recent changes in do-mestic arrangements and food preparationas well as by global fashions.
At daily auctions, licensed buyers, whosupply restaurants and other outlets inTokyo, bid through a series of hand gestures.Seven auction houses lie at the center of themarket. Though most specialize in certain
products, they compete with oneanother and with other markets.All seven have semi-permanentrelationships upstream with sup-pliers and downstream with pur-chasers. These bonds modulatemarket swings through the trans-mission of information and thelowering of transaction costs thatwould otherwise be incurred. Inaddition to these semi-permanentexchange relationships and gov-ernment licensing and regula-tions, the market is permeated orinstitutionalized by keiretsu,which are vertically integratedcombines that link fisheries,trading companies, and super-market chains. The combinesstabilize the market and limitcompetition. Yet market embed-ding extends further. For exam-ple, small retail firms that pur-chase fish for sale and keepstalls at the marketplace are of-ten organized around family ties.Their risk is modulated by theTsukiji practice of reassigningthe stalls every four to five yearsby a lottery and by formal andinformal regulations that damp-en competition.
A range of readers, from re-gional specialists to tourists, willbe interested in this well-round-ed study that displays the meritsand skills of ethnography; Bestor even pro-vides an appendix telling visitors how to vis-it and what to see in this fascinating place. Insome respects, however, the work does notresolve the issue on which it is based: em-beddedness. If markets give vent to rationalchoice, self-interest, sturdy individualism,and profit making, how is such behavior rec-onciled with the many ways in which theyare circumscribed by cultural values and so-cial relationships? Disregarding differencesbetween the approach of anthropologists andsociologists on the one side and formal econ-omists on the other, is there an inherent ten-
sion in the economy itself? How do peopleexperience, feel, and voice this tension be-tween self-interested maximization and mu-tuality? Some readers might wish to knowwhether local voices express this tension, tolearn more about its potentially dynamic ef-fects on the market, and to be exposed to the“incompletion” of economic life in Tsukiji.But Bestor provides one of the finest ethno-graphic studies that we have of a modernmarket, and he can address these questionsin his next dispatch. If you visit Japan, takethis book for its insights into the culture, aTokyo neighborhood, and the local diet.
CRE
DIT
:CO
URT
ESY
HER
BERT
F.J
OH
NSO
N M
USE
UM
OF
ART
,CO
RNEL
L U
NIV
ERSI
TY
Simpler exchange. Until the 1923 earthquake, Tokyo’s fishtrade was concentrated at Nihonbashi, which is depicted in“Clearing After Snow, Nihonbashi” from Hiroshige’s 1856 se-ries One Hundred Famous Views of Edo.
Tsukiji:The Fish Market
at the Centerof the World
Theodore C. Bestor
University of CaliforniaPress, Berkeley, 2004.440 pp. $60, £39.95.ISBN 0-520-22023-4.Paper, $24.95, £16.95.ISBN 0-520-22024-2.California Studies inFood and Culture.
B R O W S I N G S
True Warnings and False Alarms. Evaluating Fears about the Health Risks of Technology,1948–1971. Alan Mazur. Resources for the Future, Washington, DC, 2004. 199 pp. $50. ISBN1-891853-55-4. Paper, $18.95. ISBN 1-891853-56-2.
How seriously should we take claims of a newly discovered threat to public health? To helpus judge, Mazur analyzes 31 claims from the 1950s and 1960s about threats posed by a varietyof technologies, including radioactive wastes, DDT, fluoridation, mercury pollution, oral contra-ceptives, and medical x-rays. In this retrospective risk analysis, he reviews the sources and cir-cumstances of the claims, looking for differences between the 18 that are accepted as valid andthe 13 false alarms. He finds that warnings were more likely to be true if they were first raisedin reports of research by recognized scientific organizations rather than claims by advocacygroups or government agencies. For warnings from the latter sources, those that appeared in iso-lation (rather than an already charged atmosphere) were more accurate. However, there seemedto be no relation between validity and the extent to which news coverage had hyped the claim.
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004
B O O K S E T A L .
Components forcancer gene research: 500 parts highly reliable
PCR reagents
479 hours of personal time
152 pieces of cold pizza
0 girlfriends
At USB, we know that discovery doesn’t come without personal sacrifice. And for all that hard work to pay
off, you need a reagent supplier who’s just as committed as you. What you want is a bioscience partner who
provides you with products you can trust. Who collaborates with you to get results. Who responds to your
specific needs. And who isn’t going to waste what little free time you have giving you the run-around. At
USB, we’ll bring you over 30 years of experience in life sciences, a higher level of customer service, and most
importantly, a true passion for discovery. To learn more, call 800-321-9322 or visit us
at www.usbweb.com. When you get a moment, that is.
PCR Tools | Molecular Biology Reagents | Mutation Discovery | Nucleotides | Biochemicals
1719
Three laboratories recently reported der-ivation of gamete-like cells from mouseembryonic stem (ES) cells (1–4). Much
progress must be made to reach the goal ofderiving bona fide germ cells from ES cells;the chief test will be their ability to sustainnormal fertilization and development.However, these cells appear to share, to somedegree, fundamental features of gametes,namely, a haploid genome and erasure of im-prints (i.e., the molecular marks that distin-guish alleles according to their origin and areessential for normal development).
The most immediate application of ES-derived oocytes will likely be in somaticcell nuclear transfer (SCNT) (5) for re-search purposes. Clearly, many challengesremain before such gametes could be usedin human reproduction. Precisely becausethe technology is not yet within immediatereach, we believe it is timely to start devel-oping a bioethical and legal discourse.
The possibility of deriving gametes fromhuman ES cells could allow infertile individ-uals to have genetic offspring, unless the de-fect also impaired in vitro generation of ga-metes. Infertility affects roughly 2.1 millioncouples in the United States alone (6). A so-matic nucleus from the infertile member ofthe couple would be transplanted into an enu-cleated oocyte. ES cells would be derivedfrom the blastocyst stage of this cloned em-bryo and differentiated into gametes, whichwould be used for in vitro fertilization (IVF)with the naturally generated gamete from thefertile partner. Although the procedure in-volves SCNT, this would not amount to re-productive cloning, because the offspringwould have, as in normal reproduction andIVF, the genomic contribution of both par-ents. Simply, whereas the haploid genomefrom the fertile member of the couple willhave been reprogrammed (“made fit for fer-tilization”) through the normal process of ga-metogenesis, the infertile member will have
achieved the same result with an “assisted re-programming effort” mediated through theresetting activity of a donor oocyte. We sug-gest that from an ethical and legal perspec-tive, this procedure is most appropriatelyframed as a therapeutic intervention to treatinfertility. It replaces in vitro the physiologicfunction normally responsible for reprogram-ming the germline genome, analogously tothe well-established medical technologiesthat replace other deficient bodily functions.
If the technique approaches the same lev-el of safety and cost as those of current IVFprotocols, it is likely that the majority of in-fertile individuals and/or couples would wantto benefit from it. However, this does not im-ply any preeminence of genetic over socialparenthood. Although our society values so-cial parenthood highly, it still actively en-courages those who can to have genetic off-spring. Provided that the technology wouldbe widely and justly accessible, this couldfurther democratize human reproduction.
As with any medical procedure, safetywould be a crucial parameter. Faulty imprint-ing causes severe abnormalities, and carefulexperiments in animal models will have toassess the imprinting status of ES-derived ga-metes (ESDG). Another potential problemcould result from the accumulation of genet-ic damage that occurs in a somatic cell.However, ethical arguments based generallyon DNA integrity would not be tenable if itwere to be shown that oocytes or sperm fromolder individuals have amounts of damagesimilar to those of somatic lineages used forESDG generation. As with IVF, evaluation ofsafety always entails a comparison with thesafety of natural or other accepted processesrather than of ideal absolutes. The identifica-tion of the normal standard for any biologicalsystem is always a complex settlement be-tween our incomplete knowledge and therisks we are prepared to take as individualsand as a society.
ESD oocytes have been derived from male(XY) and female (XX) mouse cells (1). If theprocess could be successfully completed withhuman ES cells, i.e., derivation of a matureoocyte from a male ES cell line, this wouldhave important social implications. Two mencould potentially have a child to which bothparents contribute their genomes, one through
the natural process of spermatogenesis, theother through the assisted process of genomereprogramming down the female germline. Awoman would need to carry this embryo toterm. The possibility of an all-male or all-fe-male couple’s (7) being able to have a childsharing the genetic make-up of both parentsin virtually the same way as for heterosexualcouples is thought-provoking and can be usedas a lens through which to discern our atti-tudes toward parenting and family, as well asour notions of what is “natural.”
Same-sex couples can use assisted repro-ductive technologies (ART) in the UnitedKingdom to have children to whom they areat least in part genetically related and are ableto adopt children in several countries. Therehave been extensive analyses of the success ofsame-sex couples as parents in the context ofART and adoption (8). As with most forcefulrejections of social changes that violate pre-sumed natural laws (9, 10), so for ESDG-based technology, most objections will likelyarise from the idea that the resulting child willsomehow be harmed by the nature, novelty, or“strangeness” of the process itself. This isanalogous to the early days of IVF, when itwas suggested that “test tube” babies mightnot have a soul (11). In our view, not onlydoes a child born as a result of ART or ESDGobviously have the same moral status as achild born by natural reproduction, but wouldalso have no special advantages or disadvan-tages. Natural reproduction may be more en-joyable for humans than the in vitro ap-proaches, and that would certainly be a goodreason to prefer it. However, there is no a pri-ori reason to prefer the natural, for the naturalper se is morally neutral. The whole practiceof medicine is a comprehensive attempt tofrustrate the course of nature. If we alwayspreferred the natural as a matter of principle,we would have to abjure medicine altogether.
References and Notes1. K. Hubner et al., Science 300, 1251 (2003).2. Y. Toyooka, N. Tsunekawa, R. Akasu, T. Noce, Proc.
Natl. Acad. Sci. U.S.A. 100, 11457 (2003).3. N. Geijsen et al., Nature 427, 148 (2004).4. C. Dennis, Nature 424, 364 (2003).5. A. M. Surani, Nature 427, 106 (2004).6. National Center for Health Statistics (NCHS),
“Fertility, family planning and womens’ health: Newdata From the 1995 National Survey of FamilyGrowth” (NCHS, Hyattsville, MD, 1996).
7. T. Kono et al., Nature 428, 860 (2004).8. S. Golombok, in What Is a Parent?: A Socio-Legal
Analysis, A. Bainham, S. D. Sclater, M. Richards, Eds.(Hart, Oxford, 1999), pp. 161–180.
9. L. Kass, Valparaiso Univ Law Rev. 32, 679 (Spring1998).
10. And for a refutation of such views, see J. Harris, OnCloning (Routledge, London, 2004), p. 52ff.
11. See www.msnbc.msn.com/id/3990309/site/newsweek/12. The authors acknowledge support from the Branco
Weiss Fellowship Society-in-Science and a projectgrant from the European Commission.
G. Testa is a Branco Weiss Society-in-Science Fellow inthe Department of Genomics, BIOTEC, DresdenUniversity of Technology, Dresden, Germany. E-mail:[email protected]. J. Harris is the Sir David AllianceProfessor of Bioethics at the Manchester School of Law,University of Manchester, Manchester, M13 9PL UK.
*Author for correspondence.
G E N E T I C S
Ethical Aspects ofES Cell–Derived Gametes
Giuseppe Testa* and John Harris
POLICY FORUM
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004
1720
In one of the most dramatic incidents ofthe French Revolution, the Abbé Sicard,director of the school for the deaf in
Paris, failed to take an oath of civil alle-giance. As described by Lane (1), he wasimprisoned and sentenced to die. However,Sicard, who was devoted to establishingcommunication through sign language,was rescued through the pleas of his deafstudents. They petitioned the NationalAssembly for his release, testifying thatwithout him they would be like animals.
Deaf people have fiercely resisted cen-tury-old attempts to prevent them from us-ing their own sign language for communi-cation (2). They argue that sign language isequivalent to spoken language and thatusers of a sign language should be accord-ed the same rights as users of a spoken lan-guage. The origin and core properties ofsign language, however, remain to be eluci-dated. On page 1779 of this issue, Senghaset al. (3) address this lack of information intheir landmark study of three cohorts ofdeaf Nicaraguan signers. Their research isbased on the passion for sign language ofseveral generations of deaf children attend-ing a special education program set up in1977 in the Nicaraguan capital, Managua.In the 30 years since the program opened,the children have created a completely newlanguage—Nicaraguan Sign Language(NSL)—that has continued to expand andmature and has been passed on from onegroup of children to the next (see the pho-tographs). There are about 800 deaf NSLsigners, ranging in age from 4 to 45 years.NSL is one of hundreds of distinctive signlanguages in existence around the world(see the figure). The creation of NSL hasallowed unique insights into the essence oflanguage—both sign and spoken.
Segmentation and sequencing are con-sidered vital core properties of all lan-guages. In their investigation, Senghas etal. explicitly analyzed the segmentationand sequencing in NSL of elements such asmotion. The authors did this by showinganimated cartoon videos to three cohorts of
NSL signers of different ages and to a sam-ple of hearing Spanish-speaking Nica-raguans. In one of these videos, a cat swal-lows a bowling ball and wobbles (mannerof movement) as it descends (path ofmovement) down a steep road. The first co-hort of Nicaraguan signers, who were theinitial builders of NSL, represented mannerand path information simulta-neously in a single movementof the hand, much as theSpanish speakers did in thegestures that accompaniedtheir speech. In contrast, thesecond and third cohorts ofNSL signers overwhelminglyproduced sequential handmovements involving stringsof segmented manner-onlyand path-only elements. Suchsegmentation and sequenceelements can be embeddedwithin other signs (phrases) tobuild a hierarchical organiza-
tion of information that forms an elaboratecommunication system. Intriguingly, NSLhas evolved from a system of nonlinguisticgestures into a full sign language with itsown grammar that continues to expand andmature. Consequently, because they havelearned the language most recently, theyoungest children in the NSL communityare the most fluent signers.
Senghas et al. observe that segmentingand sequencing depend on combining ele-ments of language within a hierarchicalstructure that permits the generation of aninfinite number of messages. The mecha-nisms through which segmentation and se-quencing are achieved in NSL challengethe position that language evolves through
The author is in the Department of Psychology,University of Sheffield, Sheffield S10 2TP, UK. E-mail:[email protected]
N E U R O S C I E N C E
Signposts to the Essenceof Language
Michael Siegal
Fluency among the youngest. Nicaraguan children communicate through a sign language (NSL)that they developed over a 30-year period. The opening of an education program in 1977 inManagua (the capital of Nicaragua) brought together a community of deaf children for the firsttime in that country. The children developed their own sign language, which evolved from nonlin-guistic gestures to a full grammatical language that continues to mature. The youngest children inthe NSL community are the most fluent signers, having learned the language most recently.
PERSPECTIVES
CRE
DIT
:AN
N S
ENG
HA
S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org
1721
cultural transmission. These mechanismsmay have evolved through learning abili-ties that either shape language or havebeen shaped by language. Clearly, deafNicaraguan children have created theirown language independently of exposureto a preexisting language structure.
Regarding the part played by learning inthe shaping of language, the results of theNicaraguan study are consistent with re-search that underscores the spontaneousdevelopment of language in both hearingand deaf children. Hearing infants at 2months of age prefer speech to nonspeechsounds (4). Profoundly deaf infants of deafparents display manual babbling using a re-duced set of the phonetic units in AmericanSign Language (ASL) in a manner analo-gous to the vocal babbling of hearing in-fants exposed to a spoken language (5). Inthe first few years of development, virtual-
ly all children—whether hearing childrenexposed to a spoken language or deaf chil-dren exposed to the sign language of theirdeaf parents—acquire the grammar of theirnative language. The structure of sponta-neous gestural communication (“homesigning”) of American deaf children resem-bles more closely that of deaf children inTaiwan than that of their own hearingmothers (6). Language involves “language-making” skills—segmenting words intomorphemes and sentences into words, set-ting up a system of contrasts in morpholo-gy, and constructing syntactic structures—that do not require a language model to be
activated. Language is so resilient that itcan be triggered by exposure to a linguisticinput that is highly limited and fragment-ed—an indication of the fundamental in-nateness of grammar (7, 8).
Early language exposure shapes lin-guistic ability, in that those who becomedeaf after having acquired spoken Englishappear to be more proficient in learning
ASL than those born pro-foundly deaf with littlelinguistic experience be-fore exposure to ASL atschool. In contrast, deafpeople who are exposedearly to ASL are able tolearn spoken English bet-ter than those who havebeen exposed late (9).But do such language-shaped learning mecha-nisms stop there? Canthey be extended to allowor facilitate the acquisi-tion of, for example,mathematics or proposi-tions about the beliefsheld by the minds of oth-
ers? One question to be resolved iswhether language entails a learningmechanism that instantiates mathematicalreasoning, given that language and math-ematics share similarities in syntacticstructure (10). Another question iswhether the syntactic structure of lan-guage allows us to entertain proposi-tions—for example, “John thought thatMary knew the cookies were in the cup-board”—that permit insight into the falsebeliefs of others, or whether it is early ac-cess to conversations that alert children tothe notion that beliefs can differ from re-ality (11). Also, it is not clear whether the
innate structure of language allows pro-cessing of causal and counterfactual reasoning.
In this light, language can be regardedas mandatory to human development withwidespread, although as yet undetermined,implications for the nature of cognition.Without access to language, our commu-nication would rely on iconic representa-tions that are within the grasp of nonhu-man primates and even pigeons (12). TheNicaraguan research highlights segment-ing and sequencing as core linguistic prop-erties that develop innately and not as a re-sult of cultural transmission. Such innate-ness confers humanity on both deaf andhearing people through language creationand immersion.
References1. H. Lane, The Wild Boy of Aveyron (Bantam, New York,
1977), p. 83.2. O. Sacks, Seeing Voices (Vintage, New York, 1989).3. A. Senghas, S. Kita, A. Özyürek, Science 305, 1779
(2004).4. A. Vouloumanos, J. F. Werker, Dev. Sci. 7, 270 (2004).5. L. A. Petitto, P. F. Marentette, Science 251, 1493
(1991).6. S. Goldin-Meadow, The Resilience of Language
(Psychology Press, New York, 2003).7. N. Chomsky, Rules and Representations (Blackwell,
Oxford, 1980).8. K. Stromswold, in The New Cognitive Neurosciences,
M. S. Gazzaniga, Ed. (MIT Press, Cambridge, MA, ed. 2,2000), pp. 909–932.
9. R. I. Mayberry, E. Lock, H. Kazmi, Nature 417, 38(2002).
10. R. Gelman, B. Butterworth, Trends Cognit. Sci., inpress.
11. T. Woolfe, S. C. Want, M. Siegal, Child Dev. 73, 768(2002).
12. R. Epstein, R. P. Lanza, B. F. Skinner, Science 207, 543(1980).
Web Sources for Figurewww.deafblind.com/worldsig.htmlwww.ethnologue.com, www.handspeak.comhttp://library.gallaudet.edu/dr/faq-world-sl-country.html
American BritishSwedish
Signing across the world. Examples of sign language alpha-bets: American, Swedish, and British. British sign language isnot readily intelligible to users of ASL and, unlike ASL orSwedish sign language, uses a two-handed alphabet (13).Thegeographical distribution of sign as well as spoken languagesreflects the input of nonnative languages introduced acrosscultures. In developing countries, deaf people may use thesign language of educators and missionaries from elsewherein the world. For example, some deaf individuals inMadagascar use Norwegian sign language, whereas childrenin Nicaragua have created their own sign language.
CRE
DIT
S:(T
OP)
PRE
STO
N H
UEY
/SC
IEN
CE;
(BO
TTO
M)
AN
N S
ENG
HA
S
P E R S P E C T I V E S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004
��� ��� ����� �� ����� � ��� ��� ��� ������ ������
������������� ���������������������������� ������������ �������
��� ���� ������� ��� ���
�������� �� ���� �
��������������������� ���������������������
���������������������������������������������������� ������ ����!�"��"���������������"�#��
$���������������"�������������%��������������������������� �������������
1723
CRE
DIT
:KAT
HA
RIN
E SU
TLIF
F/SC
IEN
CE
Mitochondria are cytoplasmic or-ganelles that are crucial players innumerous cellular processes. These
include bioenergetics, metabolism of aminoacids, lipids, and iron, as well as pro-grammed cell death (apoptosis), differentia-tion, and aging (1–4). Mitochondria com-prise two membranes, the outer membraneand the folded inner membrane, and twoaqueous compartments, the intermembranespace and the matrix (see the figure). Fromyeast to humans, mitochondria form a dy-namic network in the cell that is maintainedby balancing mitochon-drial fusion and fission.The dynamic morphologyof mitochondria is criticalfor the inheritance of mi-tochondrial DNA, for thetransmission of energy,and for cellular differenti-ation, such as spermato-genesis. During apopto-sis, enhanced mitochon-drial fission and dimin-ished mitochondrial fu-sion lead to mitochondrialfragmentation, potentiat-ing the cell death re-sponse. Defects in mito-chondrial fusion havebeen linked to neurode-generative diseases likedominant optic atrophyand Charcot-Marie-Toothtype 2A disease, an inher-ited peripheral neuropa-thy. In vivo studies in yeast, Drosophila, andmammalian cells have led to the identifica-tion of many proteins that are involved di-rectly or indirectly in the maintenance of mi-tochondrial morphology. However, lack ofan in vitro system for studying mitochondri-al fission and fusion has hampered analysisat the molecular level. This is now remediedby Meeusen et al. (5) reporting on page 1747of this issue. They describe an elegant in vit-ro assay that follows the fusion of isolatedmitochondria, providing important insightsinto the ordered events of outer- and inner-membrane fusion.
Mitochondrial fusion has been considered acomplicated process that requires essential cy-
tosolic elements. Yet the assay established byMeeusen et al. is remarkably straightforwardand does not require the addition of cytosolicfactors. This implies that isolated mitochondriacontain all of the essential ingredients requiredfor fusion. Meeusen et al. used mitochondrialabeled with matrix-targeted molecules: eithergreen fluorescent protein (GFP) or red fluores-cent protein (dsRED) (see the figure).Differently colored mi-tochondria were mixed,concentrated by cen-trifugation, and incu-
bated in the presence of guanosine triphos-phate (GTP) and energy substrates to generatean inner-membrane electrical potential. Mito-chondrial fusion could be monitored directlythrough mixing of GFP and dsRED such thatthe matrix of fused mitochondria containedboth fluorescently labeled proteins (see thefigure). The centrifugation step is a crucial el-ement of the assay because it brings mito-chondria into close proximity. In vivo, this stepis probably accomplished by the cellular cy-toskeleton (5, 6).
With their assay, Meeusen et al. dissectedmitochondrial fusion into sequential outer-and inner-membrane fusion events. Outer-membrane fusion required low levels ofGTP and a mitochondrial proton gradient.Inner-membrane fusion depended on the hy-drolysis of large amounts of GTP and thepresence of an inner-membrane electricalpotential. The GTP dependence of mito-
chondrial fusion concurs with previous in vivo studies that revealed a requirement fortwo large dynamin-related guanosine tri-phosphatases (GTPases): Fzo1 (fuzzy onionsor mitofusin) of the outer membrane, andMgm1 (mitochondrial genome maintenance)of the intermembrane space (1, 2, 4). In yeastcells, Fzo1 and Mgm1 are linked together ina complex by the outer-membrane proteinUgo1 (derived from the Japanese word forfusion) (7, 8). Homologs of the fusion ma-chineries that operate in the transport of vesi-cles (such as SNARE proteins) (9) do notseem to be involved in mitochondrial fusion.However, a recent structural analysis ofmouse mitofusins (Fzo1 homologs) revealed
the presence of hydrophobic heptad repeatsin these proteins that promote the formationof mitofusin dimers (10). Like the heptad re-peats present in SNARE proteins, the mito-fusin heptad repeats form coiled-coil struc-tures that connect the mitofusins of two adja-cent mitochondria (see the figure). SNAREproteins pair in a parallel fashion to bring twovesicle membranes into close apposition (9).In contrast, mitofusins form an antiparallelcoiled coil, leaving a gap of about 10 nm be-tween the two mitochondria (10). Thus, theGTP-independent dimerization of Fzo1 mol-ecules is required for the initial tethering ofmitochondria; subsequent fusion events arelikely to be promoted by GTP-dependentsteps involving Fzo1, Ugo1, and Mgm1. Thein vitro fusion assay faithfully reflects this re-quirement because the formation of Fzo1 ho-modimers on opposing mitochondria is re-quired for matrix mixing to take place (5).
C E L L B I O L O G Y
Double Membrane FusionNikolaus Pfanner, Nils Wiedemann, Chris Meisinger
The authors are in the Institut für Biochemie undMolekularbiologie, Universität Freiburg, D-79104Freiburg, Germany. E-mail: [email protected]
Tethering ofmitochondria
GTP(low level)
GTP
GTP
GTPGTP
Mgm1
Ugo1
Ugo1
Mgm1
Fzo1 dimer
Outermembrane fusion
Innermembrane
fusion
GTP(high level)
Innermembranepotential
Matrix
Mitochondrial fusion dissected. Fusion of mitochondria requires the sequential interaction of outer and inner mem-branes. Fusion of the outer membranes of two adjacent mitochondria requires low GTP levels, whereas the subsequentfusion of the inner membranes requires high GTP levels and the presence of an inner-membrane electrical potential (5).(Box) Three components of the mitochondrial fusion machinery are known: the outer-membrane GTPase (Fzo1), the in-termembrane-space GTPase (Mgm1), and the outer-membrane protein Ugo1 that links both GTPases. Formation of Fzo1homodimers between adjacent mitochondria promotes their initial tethering. Subsequent fusion of the two mitochon-dria requires the cooperation of Fzo1, Ugo1, Mgm1, and additional fusion proteins and regulatory factors.
P E R S P E C T I V E S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004
1724
Mitochondrial fusion requires strict coor-dination and regulation because four mem-branes have to fuse, but the specificity of themitochondrial subcompartments must bemaintained. With their in vitro assay,Meeusen et al. have identified the interme-diate stages of mitochondrial fusion, whichhas enabled them to gain mechanistic insightinto the factors regulating mitochondrialmorphology. Further in vitro assays can nowbe conceived for elucidating other processesthat are critical for mitochondrial morpholo-gy, including the opposing fission reaction.
This is not the end of the story, howev-er. There are other questions that need to beaddressed. For example, which of the pro-teins found in genetic screens (4) and in themitochondrial proteome (3) are directly in-volved in mitochondrial fusion, fission, ormovement, and which are regulatory orsupportive factors? Two recent findingsprovide an interesting link between the pro-tein import and assembly machinery andthe maintenance of mitochondrial mor-phology. First, Mgm1 is present in two iso-forms of different length, both of which arerequired for fusion (11). The long isoformis partially imported into the inner mem-brane and is cleaved to the shorter isoformby a rhomboid protease. The ratio betweenthe two isoforms is controlled by the activ-
ity of the presequence translocase-associat-ed motor PAM. When PAM is impaired—for example, in the presence of low adeno-sine triphosphate levels—cleavage to theshort isoform is reduced, leading to frag-mentation of mitochondria (12). Thus, theenergetic state of mitochondria may partic-ipate in controlling mitochondrial mor-phology. Second, Mdm10 (mitochondrialdistribution and morphology protein) is re-quired for both maintenance of mitochon-drial morphology and transfer of mitochon-dria to daughter cells (1, 6). Surprisingly,Mdm10 is a subunit of the protein sortingand assembly machinery (SAM) of the out-er membrane (13). Defects in Mdm10 im-pair the assembly of the general protein im-port channel of the outer membrane.Mdm10 and other factors implicated in mi-tochondrial morphogenesis may thus influ-ence morphology in a SAM-like manner bycontrolling the assembly of functional pro-tein complexes.
The machinery for maintenance of mi-tochondrial morphology should not beviewed as a separate entity but instead asmachinery that is connected to other im-portant mitochondrial functions such asbioenergetics, DNA inheritance, and pro-tein import, assembly, and turnover (1, 2, 4,6). It is also possible that proteins may play
dual roles in morphology and other mito-chondrial processes. The challenge will beto dissect the complex process of changingmitochondrial morphology into distinctsteps in order to analyze the functional con-tributions of individual proteins. Like the invitro assays that have been established formitochondrial protein import and assembly,the fusion assay of Meeusen et al. is likelyto pave the way for developing other in vit-ro assays. Together these assays will be ableto unravel the molecular events underpin-ning the dynamic morphology of thesedouble-membraned organelles.
References1. M. P. Yaffe, Science 283, 1493 (1999).2. A. D. Mozdy, J. M. Shaw, Nature Rev. Mol. Cell Biol. 4,
468 (2003).3. A. Sickmann et al., Proc. Natl. Acad. Sci. U.S.A. 100,
13207 (2003).4. B. Westermann, Biochim. Biophys. Acta 1641, 195
(2003).5. S. Meeusen, J. M. McCaffery, J. Nunnari, Science 305,
1747 (2004).6. I. R. Boldogh, H.-C. Yang, L. A. Pon, Traffic 2, 368
(2001).7. E. D. Wong et al., J. Cell Biol. 160, 303 (2003).8. H. Sesaki, R. E. Jensen, J. Biol. Chem. 279, 28298
(2004).9. J. S. Bonifacino, B. S. Glick, Cell 116, 153 (2004).
10. T. Koshiba et al., Science 305, 858 (2004).11. A. M. van der Bliek, C. M. Koehler, Dev. Cell 4, 769
(2003).12. M. Herlan, C. Bornhövd, K. Hell, W. Neupert, A. S.
Reichert, J. Cell Biol. 165, 167 (2004).13. C. Meisinger et al., Dev. Cell 7, 61 (2004).
Double and triple covalent bonds arestandard in carbon chemistry butare unusual for heavier elements, in-
cluding carbon’s closest neighbor in the pe-riodic table, silicon. On page 1755 of thisissue, Sekiguchi et al. (1) report theachievement of a long-sought goal: thesynthesis and full characterization of thefirst compound with a silicon-silicon triplebond (see the figure) (1).
Triple bonds to silicon, the elementmost closely related to carbon, have been amajor target of research for nearly 20years. Theoretical calculations have sug-gested that it should be possible to stabilizesilicon-silicon and silicon-carbon triplebonds through the use of appropriatechemical groups attached to the atomsforming the bond (2). However, until thisweek’s report (1), laboratory evidence hadeluded chemical researchers around the
world. Behind the impressive discovery re-ported by Sekiguchi et al. lies a fascinatingsequence of investigations.
By the late 19th century, multiple bondsbetween carbon atoms and between carbonand other light elements (such as oxygenand nitrogen) were well established as vitalfeatures of organic chemistry. Chemistsnext began to searchfor multiple bondingamong the heavier ele-ments silicon, germani-um, phosphorus, ar-senic, and antimony. Inthe early 20th century,syntheses of some dou-bly bonded compoundsinvolving these ele-ments were claimed.However, upon closeexamination, all suchefforts were shown tolead to singly bondedcyclic oligomers orpolymers, not multiplybonded compounds (3).
Early theoretical papers by Pitzer (4)and Mulliken (5) rationalized these results,showing that multiple bonds between heav-ier elements should be weak. Multiple co-valent bonds will form only if p orbitals onthe two atoms overlap perpendicular to theaxis between them, resulting in a π bond.Such bonds are energetically favorable forsmall atoms, but the π overlap and hencethe bond strength decrease rapidly as theatoms become larger.
The combined experimental and theo-retical results led to the consensus ex-pressed in the “double bond rule,” which
C H E M I S T RY
Japan Bats a TripleRobert West
The author is in the Department of Chemistry,University of Wisconsin, 1101 University Avenue,Madison, WI 53706, USA. E-mail: [email protected]
Silicon Carbon Hydrogen
The molecule with the first silicon-silicon triple bond (1).
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org
P E R S P E C T I V E S
1725
states that elements outside the first row ofthe periodic table do not form multiplebonds either with themselves or with otherelements. This view was presented in mostchemistry textbooks until the 1980s. Therule collapsed, however, on 28 March 1981,when, at the end of the 15th annual NorthAmerican Organosilicon Symposium inDurham, North Carolina, two speakers an-nounced the discovery of stable chemicalcompounds containing silicon-carbon (6)and silicon-silicon (7) double bonds. Theresulting paradigm shift shook the world ofsilicon chemistry and led to the burgeoningchemistry of multiply bonded compoundsof the heavier elements, which today is notonly continuing but gaining momentum.
Key to the discovery of stable com-pounds containing Si=C bonds (silenes)and Si=Si bonds (disilenes) was the protec-tion of the double bonds by bulky sub-stituent groups, which provide both kineticand thermodynamic stability. This strategyhas also been used to synthesize other dou-bly bonded compounds of the heavier ele-ments. Stable doubly bonded compoundsare now well established for almost all theelements in periodic groups 13, 14, 15, and
16, and reactions involving these com-pounds have led to a rich and growing fieldof chemistry.
With the question of double bonds be-tween heavier elements largely settled, at-tention turned to triple bonds. Phospha-alkynes, with P≡C triple bonds, are wellknown (8), and one example of an arsenic-carbon triply bonded compound has beenreported (9). Dicoordinate compounds ofgermanium, tin, and lead with formal triplebonds have been prepared in a series of el-egant studies by Power (10). However, thelatter compounds show marked lone-paircharacter and decreasing π-overlap on thebonded atoms, reducing the bond ordersfrom 3 (a triple bond) to about 2 (a doublebond) for germanium and tin and 1 (a sin-gle bond) for lead.
Sekiguchi et al. first announced their dis-covery at the 38th North AmericanOrganosilicon Symposium in May 2004, 23years after the first double bonds to siliconwere reported. Their disilyne is obtained asemerald-green crystals and is stable up to127°C. The triply bonded silicon atoms aresterically protected by extremely bulky sub-stituent groups (see the figure). The distance
between the central silicon atoms is consis-tent with a true Si≡Si triple bond, as is thebond order. In sharp contrast to the C≡Ctriple bond in acetylenes, the two Si-Si πbonds in the new molecule are not equivalent.
The synthesis of a stable disilyne is amilestone both for silicon chemistry andfor multiple-bond chemistry in general.Further examples of disilynes are likely tobe synthesized, and studies of their chemi-cal bonding and chemical reactions shouldprovide a new chapter in silicon chemistry.Meanwhile, the syntheses of compoundswith silicon-carbon and silicon-nitrogentriple bonds remain as challenges for thefuture.
References1. A. Sekiguchi, R. Kinjo, M. Ichinohe, Science 305, 1755
(2004).2. S. Nagase et al., J. Organomet. Chem. 611, 264
(2000).3. A. H. Cowley, Polyhedron 3, 389 (1984).4. K. S. Pitzer, J. Am. Chem. Soc. 70, 2140 (1948).5. R. S. Mulliken, J. Am. Chem. Soc. 77, 884 (1955).6. A. G. Brook et al., Chem. Commun. 1981, 317 (1981).7. R. West, M. J. Fink, J. Michl, Science 214, 1343 (1981).8. M. Regitz, Chem. Rev. 90, 191 (1990).9 G. Maerkl, H. Sejpka, Angew. Chem. Int. Ed. 25, 264
(1986).10. P. P. Power, Chem. Commun. 2003, 2091 (2003).
Hexose carbohydrates come in manyforms, including the common sugarglucose, and are integral to biologi-
cal processes as diverse as cell signaling,inflammation, the immune response, andtumor cell metastasis (1). Each function is
specific to a partic-ular form of hexose,but studying howstructure relates tofunction is limited
by the difficulty of obtaining pure samplesof the hexoses and their derivatives. The denovo construction of complex, differentiat-ed carbohydrates by chemical synthesis isfeasible but challenging owing to the struc-tural and stereochemical complexity ofthese polyhydroxylated compounds. Theideal strategy for synthesizing the hexosecarbohydrates would join three simple, α-oxygenated, two-carbon aldehydes by se-quential aldol addition reactions with high
enantio- and diastereoselectivity. On page1752 of this issue, Northrup and MacMillan(2) describe remarkable, two-step, stereo-selective syntheses of several polyol-differ-entiated hexoses from achiral two-carbonbuilding blocks. A dash of the amino acid L-proline (1) and classical organic chemicalreactivity are the keys to this powerful newsynthesis of these six-carbon sugars.
The Northrup-MacMillan route to thehexoses exploits proline’s tendency to con-dense with carbonyl compounds, a reactionthat is fundamental in nature and chemicalsynthesis. The nitrogen atom of proline canattack the electrophilic carbonyl carbon ofaldehydes and ketones. Collapse of thetetrahedral carbinolamine intermediate re-leases a molecule of water and yields anelectrophilic iminium ion. Although animinium ion can be attacked by nucleo-philes, it can also lose a proton to a suitablebase to give an enamine, which has a nu-cleophilic carbon and thus is a particularlyuseful reagent in organic synthesis. In the1950s, the Stork laboratory demonstratedthat enamines, especially pyrrolidine-
derived enamines, undergo carbon-carbonbond–forming reactions with a range ofalkyl halides and acid chlorides (3). L-Proline (1) is a chiral pyrrolidine and anextraordinarily useful catalyst for stereose-lective aldol, Mannich, and various oxida-tive reactions (4). It condenses with alde-hydes such as 2 to produce a new bifunc-tional reactive species 3 that can activatethe carbonyl group of another molecule of2 for the crucial enamine aldol bond for-mation. The water molecule released in theformation of the proline-derived enaminehydrolyzes the iminium ion 4, which gen-erates the desired aldol dimer 5 as the ma-jor component of a 4:1 mixture of diastere-omers, and returns the proline catalyst tothe reaction medium for another turnthrough the catalytic cycle. The enantiose-lectivity observed in the proline-directedsynthesis of 5 is excellent (5).
A remarkable and useful feature of theNorthrup-MacMillan route to the hexosesis that the initial proline-catalyzed aldoldimerization of 2 stops at the stage of thefour-carbon aldehyde 5. Although it is notentirely clear why the reaction stops at 5, itmay be that an internal hydrogen bond di-minishes the affinity of the carbonyl oxy-gen of 5 toward the type of Brønsted acidactivation shown in 3. Compound 5 resistsfurther reaction with proline, but it can beactivated with oxophilic Lewis acids suchas MgBr2 or TiCl4 for a diastereoselectiveMukaiyama aldol addition reaction (6)
C H E M I S T RY
A Dash of ProlineMakes Things Sweet
Erik J. Sorensen and Glenn M. Sammis
The authors are in the Department of Chemistry,Princeton University, Princeton, NJ 08544, USA. E-mail: [email protected]
Enhanced online atwww.sciencemag.org/cgi/content/full/305/5691/1725
P E R S P E C T I V E S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004
1726
with an enol silane derived from an α-oxy-genated aldehyde 2. This type of aldol re-action generates a new carbon-carbonbond, two new oxygen-bearing stereocen-ters, and a transient oxocarbenium ion thattriggers the final cyclization to the pyranring of the hexoses. The stereochemicalcourse of this final aldol addition is tunableby simple adjustments in the experimentalconditions. Simple two-carbon aldehydesand sequential proline- and Lewisacid–mediated aldol reactions are the key-
stones for the mostexpedient synthe-ses of these hexos-es reported so far.
This is one ofseveral importantrecent advances inthe field of catalyticasymmetric synthe-sis that is based onthe chemistry of theamino acid proline(4, 7). This renais-sance in the use ofproline in asym-metric catalysis isrooted in the earlystudies of enaminechemistry by Storkand co-workers (3)and the pioneering
research on proline-catalyzed aldol cycliza-tions by Hajos, Parrish, Eder, Sauer, andWiechert (8, 9). Asymmetric enamine aldoladditions are also at the heart of the mecha-nisms of the class I aldolases (10) and cer-tain catalytic antibodies (11). These findingshave inspired recent innovations featuringproline-based asymmetric organocatalysis.The important studies of List et al. (12) andNorthrup et al. (5) demonstrate that proline,with a molecular weight of only 115, pro-vides access to the world of enamine-cen-
tered asymmetric catalysis and is capable ofeffecting clean and stereoselective aldol ad-dition reactions.
There is great power in the experimen-tally straightforward process described byNorthrup and MacMillan (2) because itrapidly produces diverse, differentiatedhexoses, even fully 13C-labeled hexoses,for research in glycobiology, medicinalchemistry, and metabolomics. This newsynthesis affords an important type of mo-lecular complexity from commonplace mo-lecular building blocks.
References and Notes1. P. Wang, C. Bertozzi, Eds., Glycochemistry: Principles,
Synthesis, and Applications (Marcel Dekker, New York,2001).
2. A. B. Northrup, D. W. C. MacMillan, Science 305, 1752(2004); published online 12 August 2004 (110.1126.1101710).
3. G. Stork, R. Terrell, J. Szmuszkovicz, J. Am. Chem. Soc.76, 2029 (1954).
4. B. List, Tetrahedron 58, 5573 (2002).5. A. B. Northrup, I. K. Mangion, F. Hettche, D. W. C.
MacMillan, Angew. Chem. Int. Ed. 43, 2152 (2004).6. T. Mukaiyama, K. Banno, K. Narasaka, J. Am. Chem.
Soc. 96, 7503 (1974).7. M. Movassaghi, E. N. Jacobsen, Science 298, 1904
(2002).8. Z. G. Hajos, D. R. Parrish, J. Org. Chem. 39, 1615 (1974).9. U. Eder, G. Sauer, R. Wiechert, Angew. Chem. Int. Ed.
Engl. 10, 496 (1971).10. A. Heine et al., Science 294, 369 (2001).11. C.-H. Lin et al., Proc. Natl. Acad. Sci. U.S.A. 94, 11773
(1997).12. B. List, R. A. Lerner, C. F. Barbas III, J. Am. Chem. Soc.
122, 2395 (2000).
NH
1L-Proline
(catalytic amount)
O H
N
O O
POPO
O H
N
O O
POPO
H
O
OP OP
OH
Hydrolysis
OPO
PO
OH
OP
OH
OPO
PO
OH
OP
OH OPO
PO
OH
OP
OH
Glucose
Mannose Allose
H
Enamine aldolbond formation
Mukaiyamaaldol
CO2H
Mukaiyamaaldol
Mukaiyamaaldol
H
O
OP
H
O
OP
32P = Si(i-Pr)3
4
5(95% ee)
Northrup-MacMillan route to the hexoses. L-Proline–catalyzed enam-ine aldol bond formation (2 → 4) is followed by tandem Mukaiyama aldolbond formation and cyclization to form differentially protected hexoses.
The ongoing epidemic of allergic asth-ma in the developed world has lenturgency to the quest to understand
the pathogenesis of this chronic, often de-bilitating, inflammatory disease. There is abroad consensus that allergic asthma is amaladaptive immune response to otherwiseharmless inhaled substances in geneticallysusceptible individuals. This elegantlyvague formula hides considerable igno-rance and controversy. For example, thereis heated debate about whether white blood
cells called eosinophils are involved in thepathogenesis of asthma. Although the pres-ence of eosinophils at sites of allergic in-flammation was recognized in the 1800swith the first pathological description offatal status asthmaticus (1), the experimen-tal elucidation of the part played by thesecells in allergic asthma has been convolut-ed. Two papers in this issue, by Lee et al.(2) on page 1773 and Humbles et al. (3) onpage 1776, revisit this controversy usingelegant transgenic techniques. Both studiessuggest that eosinophils are an integral partof experimental allergic asthma, but apartfrom this common finding they report di-vergent results. This divergence suggestscomplexities that will keep the asthma re-
search field contentious and lively formany years to come.
The cardinal features of allergic asthmainclude elevated concentrations of serumimmunoglobulin E (IgE), pulmonaryeosinophilia, airway hyperresponsiveness,excessive airway mucus production, andairway remodeling marked by peribronchi-olar collagen deposition and increases inairway smooth muscle mass. As with otherallergic diseases, asthma is clearly depend-ent on CD4+ T lymphocytes that areskewed to a T helper cell 2 (TH2) pheno-type (4). Indeed, TH2, cytokines such as in-terleukin-4 (IL-4), IL-5, IL-9, and IL-13drive asthma pathogenesis. The evidencefor this is that (i) IL-4 drives the T helperresponse in favor of TH2, resulting in en-hanced production of IgE; (ii) IL-5, alongwith GM-CSF (granulocyte-macrophagecolony-stimulating factor) and IL-3, is im-portant for the production of eosinophils;(iii) IL-13 is required for airway hyperre-sponsiveness and mucous metaplasia, thedownstream pathophysiological featuresmost closely linked with clinical asthma;
B I O M E D I C I N E
Eosinophils in Asthma:Remodeling a Tangled Tale
Marsha Wills-Karp and Christopher L. Karp
M. Wills-Karp is in the Division of Immunobiology andC. L. Karp is in the Division of Molecular Immunology,Cincinnati Children’s Hospital Medical Center,Cincinnati, OH 45229, USA. E-mail: [email protected]
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org
P E R S P E C T I V E S
1727
and (iv) all of these cytokines, togetherwith TGF-β (transforming growth fac-tor–β), have been implicated in airway re-modeling. Thus, TH2 lymphocytes and thecytokines they produce are key players inallergic asthma. But do eosinophils, theubiquitous companions of TH2 cells, alsoplay a part in asthma pathology, or are theyunjustly maligned bystanders?
A role for eosinophils is plausible giventheir ability to secrete both cytotoxic(eosinophil peroxidase) and bronchoactive(leukotrienes) mediators (5). Eosinophilscan also present antigens and secrete TH2cytokines (6), perhaps amplifying or per-petuating TH2 inflammatory processes atsites of disease. Despite this promisingrepertoire of immune regulatory and effec-tor properties, pulmonary eosinophilia hasoften been separable from disease patho-physiology in mouse models of allergicasthma. For example, neutralization of IL-13 effectively blocks allergen-driven air-way hyperresponsiveness and mucousmetaplasia without substantially alteringthe number of eosinophils in the lungs (7).To date, experimental depletion ofeosinophils through antibody-mediated orgenetic targeting of IL-5 has yielded con-flicting results: both pronounced and negli-gible effects on asthma pathophysiology(8–10). Because eosinophils are not com-pletely eliminated by such depletion strate-gies, these results have been questioned.
In asthma patients, the number of air-way eosinophils is associated directly withdisease severity. Effective corticosteroidtherapy is associated with a reduction in thenumbers of such cells. But guilt by associ-ation is not enough. Following work inmouse models, therapeutic trials ofeosinophil depletion using humanizedmonoclonal antibodies against IL-5 are un-der way. In an initial randomized, double-blind, placebo-controlled study of mildasthmatics, a single dose of anti-IL-5 anti-body reduced the number of eosinophils inboth blood and sputum without appreciablyaltering airway function or disease symp-toms (11). The study design leaves openthe question of whether a complete andsustained reduction in eosinophils is neces-sary for therapeutic benefit. Notably, a fol-low-up study using a multiple-dosing regi-men led to the attenuation of several in-dices of airway remodeling, including ma-trix protein deposition and airway smoothmuscle hypertrophy. However, there wereno beneficial effects on airway physiologyor symptoms in the treated asthmatics (12).The experimental and therapeutic contro-versy continues.
Bona fide eosinophil-deficient micehave now been generated successfully us-ing two different transgenic strategies (2,
3). Humbles et al. generated mice withtargeted mutations in the gene encodingGATA-1, a transcription factor essentialfor the erythroid and megakaryocytic dif-ferentiation of immature myeloid cells.Whereas genetic deletion of GATA-1 leadsto embryonic lethality, deletion of a high-affinity GATA-1 binding site in the GATA-1 promoter (∆dbl GATA) leads to selectiveablation of the eosinophil lineage (13). In adifferent approach, Lee et al. targetedeosinophils through transgenic expressionof the diphtheria toxin A chain under con-trol of the eosinophil peroxidase promoter(PHIL). Both types of transgenic mice lackeosinophils, and that’s where the similari-ties end. The ∆dbl GATA mice still showairway hyperreactivity and excess mucusproduction, the “acute” pathophysiologicalmanifestations of asthma. Such mice, how-
ever, also show attenuation of airway re-modeling. We note that such findings arecongruent with the results of trials usingIL-5–specific antibodies in humans. On theother hand, PHIL mice are completely pro-tected from developing airway hyperre-sponsiveness and show partial protectionfrom airway mucous metaplasia. The au-thors did not report whether PHIL mice al-so exhibit diminished airway remodeling.The authors allude to data indicating thatTH2 cytokine production is suppressed dur-ing experimental asthma in PHIL mice(which was not reported in the ∆dbl GATAmice). Such findings suggest an obviousway in which eosinophils could promoteasthma pathophysiology, that is, throughproduction of TH2 cytokines (for example,IL-13) at the site of disease.
What explains the differences in these
CRE
DIT
:KAT
HA
RIN
E SU
TLIF
F/SC
IEN
CE
DC
TH2
Survivalactivation
Eotaxin
TH2
TH2
TH2
CD34+
EosinophilIL-4IL-13
IL-13
IL-5
IL-5
IL-5
VLA-4
VCAM-1Goblet cellmetaplasia
Airwayhyperresponsiveness Muscle
hypertrophy
Matrixdeposition
Allergen
Eosinophils and asthma. Presentation of allergens at the airway surface by antigen-presenting cells(dendritic cells) results in TH2 cell differentiation and TH2 cytokine production (IL-4, IL-13, and IL-5)in asthmatic individuals. CD4+ T cells orchestrate the ensuing inflammatory response characterizedby an influx of eosinophils into the airway spaces in response to cytokines. Eosinophils are recruit-ed into the airway spaces from the bone marrow through several steps coordinated by TH2 cy-tokines. First, their development in the bone marrow from CD34+ progenitor cells occurs under theinfluence of cytokines (IL-5, IL-13, and GM-CSF) produced by CD4+ T cells. Once cells are commit-ted to the eosinophil lineage, they move from the bone marrow into the vasculature under the guid-ance of IL-5. Their movement through the blood vessel walls into sites of TH2-mediated inflamma-tion is controlled by IL-4 and IL-13.These cytokines induce expression of vascular cell adhesion mol-ecule–1 (VCAM-1), which binds to its receptor (VLA-4) on the surface of eosinophils. This leads tothe preferential extravasation of eosinophils through vessel walls into sites of inflammation. Onceactivated by IL-5 or chemokines (eotaxin), eosinophils may contribute to the pathogenesis of aller-gic asthma by acting on various cells in the airway walls (fibroblasts, smooth muscle cells, and epi-thelial cells) or by secreting additional TH2 cytokines. Under certain circumstances, these effects cul-minate in enhanced sensitivity of the airways to various stimuli, resulting in airway hyperrespon-siveness, overproduction of mucus, increased mucus secretion, and deposition of collagen aroundthe basement membrane.
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004
P E R S P E C T I V E S
ProteinExpressionVWR puts the inExpress“ ”
Satisfy your laboratory supply needs withVWR International. Not only does VWRoffer over 750,000 scientific products,but we also make it fast and easy to order them!
Check out our selection of protein expressionproducts. They can be easily ordered online at
vwr.com. The VWR bioMarke™Life Sciences Program
provides access to top qualityproducts and support from our life science specialists for yourresearch, development andproduction efforts.
The extensive VWR™ Collection productportfolio offers top quality instruments,chemicals, equipment and supplies—all withremarkable value. The VWR Microcentrifugeshown below is just one example of the qualityand performance that you will experience withVWR Collection products.
Make VWR International your “Express” sourcefor life science supplies. Contact us today
to find out more.
Visit
for excitingpromotionaloffers!
©2004 VWR International, Inc.VWR bioMarke and VWR anddesign are trademarks of VWRInternational, Inc.
1729
two studies? Why are eosinophils critical toacute asthma pathophysiology in one strainbut not the other? One obvious explanationis background strain variability. Allergicasthma is known to be a multigenic syn-drome in both mice and humans. The ∆dblGATA mice were bred on a Balb/c back-ground, whereas the PHIL mice were bredon a B6 background. In congruence withthe current findings, IL-5–deficient miceon a Balb/c background are protected fromairway hyperreactivity, whereas IL-5–defi-cient mice on a B6 background are not (9,14). Of course, it remains possible that themethod of eosinophil deletion in PHILmice leads to effects outside of theeosinophil lineage, something hinted at bythe >50% increase in peripheral bloodleukocytes seen in such mice. Might diph-theria toxin–mediated apoptotic deletion ofmaturing eosinophils (for example, in
lymph nodes) (6) also have broad immuno-suppressive effects (15)? In any case,crossing the two transgenes onto the recip-rocal mouse backgrounds should provide adefinitive answer.
The current studies point to a role foreosinophils in experimental allergic asth-ma. Taken together, however, the new find-ings suggest that, although eosinophils maybe essential for airway remodeling, theymay not contribute to airway hyperreactiv-ity or mucous metaplasia. Although suchcomplexities may dismay partisans of theplucky eosinophil, they provide a satisfy-ing experimental mirror of the multigenicsubstrates and phenotypic heterogeneityexhibited by patients with allergic asthma.Targeting eosinophils may well provide ef-fective therapy for a subset of asthma pa-tients. More prosaically, the elegant trans-genic mouse models presented in these two
studies should lead to new insights into thepart played by eosinophils in other allergicdisorders, parasitic infections, and cancer.
References1. H. L. Huber, K. K. Koessler, Arch. Intern. Med. 30, 689
(1922).2. J. J. Lee et al., Science 305, 1773 (2004).3. A. A. Humbles et al., Science 305, 1776 (2004).4. M. Wills-Karp, Annu. Rev. Immunol. 17, 255 (1999).5. G. Gleich, C. R. Adolphson, K. M. Leiferman, Annu. Rev.
Med. 44, 85 (1993).6. H. Z. Shi, A. Humbles, C. Gerard, Z. Jin, P. F. Weller, J.
Clin. Invest. 105, 945 (2000).7. M. Wills-Karp, Science 282, 2258 (1998).8. T. T. Kung et al., Am. J. Respir. Cell Mol. Biol. 13, 360
(1995).9. P. S. Foster, S. P. Hogan, A. J. Ramsay, K. I. Matthaei, I. G.
Young, J. Exp. Med. 183, 195 (1996).10. D. B. Corry et al., J. Exp. Med. 183,109 (1996).11. M. J. Leckie et al., Lancet 356, 2144 (2000).12. P. Flood-Page et al., J. Clin. Invest. 112, 1029 (2003).13. C. Yu et al., J. Exp. Med. 195, 1387 (2002).14. S. P. Hogan et al., J. Immunol. 161, 1501 (1998).15. P. P. McDonald et al., J. Immunol. 163, 6164 (1999).
Most inner solar system materialshave distinct oxygen isotopic com-positions (see the figure, inset). A
more pronounced variation is observed forsome high-temperature components of themost primitive meteorites (see the figure),which represent the most pristine samplesof the solar nebula from which our solarsystem formed. Clearly, the solar systemhas 16O-rich and 16O-poor reservoirs (1),but exactly what this observation tells usabout the early solar nebula remains elu-sive. Part of the difficulty is that the oxy-gen isotope composition of the Sun—which represents 99.87% by mass of thesolar system—is not known with sufficientprecision to determine how the planetarymaterials evolved from the bulk reservoir.
Recently, a new class of models (2–4)has been proposed to resolve this long-standing problem. In contrast to earliermodels that concentrated on the symmetryof minor gas species such as O3, O2, andCO2 (5), the new models focus on photo-chemical isotopic effects on major volatilespecies such as CO (second in abundanceto H2 in molecular clouds). On the basis ofsuch a model, Yurimoto and Kuramotopostulate on page 1763 of this issue (4) that
oxygen isotope fractionation occurred inthe molecular cloud that collapsed to formthe solar nebula. They also explain howthese isotopic effects may have been trans-ported into the primitive meteorites (calledchondrites) of the inner solar system.
The new model (4) tracks a parcel ofdust and gas in a molecular cloud with aninitially homogeneous oxygen isotopiccomposition. When the molecular cloud issubjected to ultraviolet (UV) radiationfrom an external source such as a nearbystar, photodissociation of CO occurs. Themost abundant isotopomer, 12C16O, quick-ly consumes all UV photons that have theappropriate energies for dissociating it,and its dissociation therefore stops at thecloud surface. Dissociation of less abun-dant isotopomers such as 12C17O and12C18O requires UV photons with slightlydifferent energies. Because these photonsare not consumed as quickly by the lessabundant species, dissociation of the lattercontinues deeper inside the molecularcloud. This “UV self-shielding” is widelyknown to occur on the edge of molecularclouds. It generates 17,18O-rich atomicoxygen and 16O-rich CO inside the molec-ular cloud.
In the dense, cold core of the molecularcloud, the 17,18O-rich atomic oxygen rapid-ly reacts with hydrogen to form a water-icemantle on silicate grains. The grains retain
the original average oxygen isotope compo-sition of the molecular cloud, whereas themantles are 17,18O-enriched. When the mo-lecular cloud collapses and the young stel-lar object ignites, its surroundings are heat-ed through radiation and/or shocks that willchemically and thermally process the ice-mantled grains, producing the observedisotopic heterogeneity along the δ17O/δ18Oline with slope 1 (see the figure) (6).
Clayton (2) recently suggested that theUV source for self-shielding may havebeen the nascent Sun itself. Because thenebula was very dense and opaque, UV ir-radiation is thought to have occurred onlyvery near to the young Sun (7). In this sce-nario, it is unclear how the chondrite ma-trix (which, in contrast to some inclusions,was never processed above 400 K) inherit-ed its 17,18O-rich signature or how most ofthe water in the solar system became17,18O-rich near the Sun and were trans-ported to the outer solar system.
Lyons and Young (3) suggest that COwas dissociated at the disk surface of thesolar nebula, further away from the Sun,where the UV source could be either theSun or other nearby stars. However, itseems that transport of 17,18O-rich waterfrom the disk surface down to the nebularmidplane would have taken too long for theoxygen isotopic signature to be locked intothe planetary system. Furthermore, theircalculated δ17O/δ18O slope of 1.05 to 1.10(3) is higher than the observed value of0.94 to 1.00 (see the figure).
The model of Yurimoto and Kuramoto(4) is not subject to such a time constraint,because the 17,18O-rich water is generatedin the molecular cloud well before the so-lar-nebula disk forms. The close associa-tion of the icy mantle with the dust grains
P L A N E TA RY S C I E N C E
Predicting the Sun’sOxygen Isotope Composition
Qing-zhu Yin
The author is in the Department of Geology,University of California, Davis, CA 95616, USA.E-mail: [email protected]
P E R S P E C T I V E S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004
1730
readily explains the 17,18O-rich signaturesin the chondrite matrices. However, the au-thors simply assume that the δ17O/δ18Oslope is 1 (4). Clearly, the exact productionratio of 17O/18O in CO self-shielding as afunction of UV fluence needs to be deter-mined in the laboratory to better than 5%,because the astronomical observations aretoo imprecise.
According to the self-shielding models,the oxygen isotopic composition of thebulk solar nebula (hence the Sun) hasδ17,18O = –50‰ (see the figure), similar tosome minor constituents of chondrites,
such as calcium-aluminum–rich inclusions(CAIs), amoeboid olivine aggregates, andsome rare chondrules (most chondrules are16O-depleted). All other inner solar systemmaterials must then have changed by morethan 50‰ from the original composition toreach the current values just above 0‰ (seethe figure).
However, some rare chondrules (8) haveδ17, 18O as low as –70 to –80‰ (see the fig-ure), implying that even CAIs and amoe-boid olivine aggregates near –50‰ are notthe most pristine representatives of the bulksolar nebula. This raises the question ofwhether any existing traces of material re-
tain the oxygen isotope composition of theprimordial solar nebula.
The self-shielding model dependsstrongly on the available UV flux: Toomuch UV will dissociate all CO, whereastoo little will not dissociate it at all. In bothcases, no isotopic fractionation occurs.Thus, if the model is correct, the observedoxygen isotopic variations put constraintson the total UV fluence in our solar nebula,which may in turn provide informationabout the astrophysical settings in whichour solar system originated. Isotopic ef-fects in elements other than oxygen, such
as hydrogen, nitrogen (9), and sulfur, mayalso elucidate the astrophysical site whereself-shielding occurs.
Clayton originally proposed that theslope 1 line represents mixing of pure 16O(produced in stellar nucleosynthesis by Heburning) with the “normal” oxygen isotopemixture typical for most inner solar systemmaterials (1). He now advocates the self-shielding model (2), but the nucleosynthet-ic origin may still be viable. Observed 60Feconcentrations in chondrites (10, 11) indi-cate that a supernova must have contributedfreshly synthesized material to the solarnebula shortly before the birth of the solar
system. One presolar grain with almost-pure 16O (δ17O = – 921 ± 47‰ and δ18O =– 830 ± 65‰) has been found in a chon-drite (12); it probably originated in the su-pernova. The slope 1 line would then con-strain the dilution factor of the interstellarmedium by the freshly synthesized super-nova material to between 0.01 and 5%.
A verdict on the predicted solar oxygenisotopic composition would have been ex-pected soon had NASA’s Genesis spacecraftreturned the solar wind samples safely toEarth as planned on 8 September 2004. Themission aimed to measure the oxygen iso-tope composition of the solar wind to betterthan 1‰. However, oxygen isotope meas-urements on metal grains recovered fromlunar soil—exposed to the solar wind for 4billion years, instead of just 884 days—in-dicate an extreme 17,18O enrichment of up to80‰ (13), opposite to the prediction of theself-shielding models (2–4). This observa-tion highlights potential challenges to deter-mining the solar oxygen isotopic composi-tion from solar wind samples.
NASA’s Stardust spacecraft collectedinterstellar dust particles in May 2000 and2002. In January 2004, it encounteredcomet Wild 2 and collected at least 1000cometary particles. Once returned to Earthin January 2006, these samples may be-come the most important asset to study thelink between interstellar and nebular chem-istry. NASA has also just launched the“Oxygen in the Solar System” initiativeaimed at deriving an overarching model toelucidate the origins of isotopic complexi-ty. We may not have the final answer towhat is arguably the most fundamental out-standing problem in cosmochemistry, butwe will soon learn a great deal.
References and Notes1. R. N. Clayton, Annu. Rev. Earth Planet. Sci. 21, 115
(1993).2. R. N. Clayton, Nature 415, 860 (2002).3. J. R. Lyons, E. D. Young, Lunar Planet. Sci. 35, 1970
(2004).4. H. Yurimoto, K. Kuramoto, Science 305, 1763
(2004).5. M. H. Thiemens, Science 283, 341 (1999).6. δ17,18O = [(17,18O/16O)Sample/(17,18O/16O)SMOW – 1] ×
1000; SMOW stands for Standard Mean Ocean Water.The less conventional MC notation used in (4) is con-verted to δ17,18OSMOW notation with δ17,18OSMOW =δ17,18OMC – 50‰.
7. F. H. Shu, H. Shang, T. Lee, Science 271, 1545(1996).
8. S. Kobayashi, H. Imai, H. Yurimoto, Geochem. J. 37,663 (2003).
9. R. N. Clayton, Meteorit. Planet. Sci. 37 (Suppl.), 35 (2002).10. S. Tachibana, G. R. Huss, Astrophys. J. 588, L41
(2003).11. S. Mostefaoui, G. W. Lugmair, P. Hoppe, A. El Goresy,
New Astron. Rev. 48, 155 (2004).12. L. R. Nittler, C. M. O.Alexander, J.Wang, X. Gao, Nature
393, 222 (1998).13. T. R. Ireland, P. Holden, M. Norman, J. Clarke, Lunar
Planet. Sci. 35, 1448 (2004).14. E. D. Young, S. S. Russell, Science 282, 452 (1998).
60
4
0
–4
–8–6 –2–4 20 64
40
20
0
–20
–40
–60
–80
–100
–120–120 –100 –80 –60 –40
Mass-independentfractionation line(slope 1)
Cometary CO gasδ17,18O = –100 to –450‰
Cometary H2O iceδ17,18O = 50 to 200‰
Terrestrial fractionation line(slope ~ 0.52)
Mars, Moon, Vesta
High-temperature componentsof chondrites
Chondrites
Chondrites
Slope ~0.52
Slope 1
–20
δ18O
δ17 O
0 20 40 60
Three-oxygen isotope diagram. 17O/16O and 18O/16O ratios of samples, normalized to StandardMean Ocean Water (6). Most planetary materials are clustered near the origin (inset A), subpar-allel to the terrestrial fractionation line defined by the mass-dependent relation δ17O = 0.52δ18O. High-temperature components of chondrites (such as CAIs, amoeboid olivine aggregates,and chondrules) follow the mass-independent fractionation line with slope 1. Some chondruleshave extreme values of δ17,18OSMOW around –80‰ (data points with error bars) (8). Data are from(1, 8, 14). Oxygen isotope compositions of the Sun, cometary H2O, and cometary CO are ac-cording to (4).
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org
P E R S P E C T I V E S
ScienceNOW is a daily collection of news items from every corner of the world of science.Covering a wide spectrum of fields, ScienceNOWoffers a variety of articles to keep you informed ofwhat's happening. Our newest member benefit isScienceNOW e-mail alerts – science articles sentdirectly to your inbox on a daily or weekly basis.
Sign up today and start receiving the latestscientific news stories automatically!http://sciencenow.sciencemag.org/cgi/alerts/etoc
What’s the best way to getscience news in your inbox
on a daily basis?
Sign up for ScienceNOW e-mail alerts
Jeffery Cox, Ph.D., University of California, San Francisco
Chuan He, Ph.D.,University of Chicago
Gavin MacBeath, Ph.D.,Harvard University
Samuel Wang, Ph.D., Princeton University
Elizabeth Winzeler, Ph.D.,The Scripps Research Institute
The W. M. Keck Foundation Distinguished YoungScholars in Medical Research Program is a ten-year,$50 million initiative designed to give 50 of the nation’sbest young scientists the financial resources they needto pursue pioneering research into the fundamentalmechanisms of human disease.
Under the program, each investigators’ sponsoringinstitution will receive a grant of up to $1 million tofund these distinguished young scholars’ work.
Selected for their ability to carry forward groundbreakingbasic medical research, potential for making a significantimpact on the field of biomedicine, and capacity forfuture leadership, the W. M. Keck Foundation believesthese investigators will make profound advancementsin critical areas of medical research.
We are proud to offer them our congratulations andongoing support.
The W. M. Keck Foundation is proud to announce its SixthClass of Distinguished YoungScholars in Medical Research
The W. M. Keck Foundationwww.wmkeck.org
WITH YOUR GIFTSUBSCRIPTION
FREE
Order today at: http://promo.aaas.org/schoolp
Q: How do you help a science student get the best education?
A: Give AAAS Membership and Science at a special student rate and a FREE Deluxe Carry All Bag.
��������������������� ������ �� �������� ��������������� ������������������������������ ������ ������ �������� ������� ������� ��������� �������������������������������������!���
������������������� ���������������������������������������������!�"�����������������������#
� "���������� ������������������ ��������#�������$$%
� &����#�����������������������'���������������������� ���������������� �(����)���
� *���� ������ ���� ���#� �� ���������'������ �����������������'��
� ���������������������� ��������������� �������������������*����
+�������,��� -
/+3��5��%%���������/������+���� /+3�7:��%���������������/+3�7%�%%���������;�������������##���/+3�<%�%%�������������������������
FREEWITH YOUR GIFTSUBSCRIPTION
Living with the Past: Evolution, Development, andPatterns of Disease
Peter D. Gluckman1* and Mark A. Hanson2
Epidemiological observations have led to the hypothesis that the risk of developingsome chronic noncommunicable diseases in adulthood is influenced not only by geneticand adult life-style factors but also by environmental factors acting in early life.Research in evolutionary biology, developmental biology, and animal and human phys-iology provides support for this idea and suggests that environmental processes influ-encing the propensity to disease in adulthood operate during the periconceptual, fetal,and infant phases of life. This “developmental origins of health and disease” conceptmay have important biological, medical, and socioeconomic implications.
It has been proposed that the risk of suffer-ing chronic diseases depends in part onenvironmental influences acting early in
life (1). The “developmental origins of healthand disease” model arose largely from retro-spective epidemiological studies of humanpopulations (1–3). The relative size and im-portance of such developmental and nonge-netic effects have been disputed (4, 5). Wereview the clinical and experimental data andthe mechanisms involved, andevaluate the wider implicationsarising from this concept.
Epidemiological and ClinicalStudiesRetrospective epidemiological anal-ysis of causal factors in a diseaseprocess spanning most of a lifetimeis challenging because concurrentrisk factors carry greater weight andit is difficult to identify or attributerisk to distant, early-life factors. Inaddition, direct study of the poten-tial impact of development on laterdisease outcomes is difficult be-cause of the need for unbiased co-horts with both perinatal data andhealth outcomes documented wellinto middle age. Thus, most studieshave used surrogate (i.e., indirect orproxy) measures of disease risk,such as systolic blood pressure or fasting insulin/glucose ratios. Although the definition of the
health/disease boundary is inevitably arbitrary,where clinical cardiovascular or metabolic dis-ease is the measured outcome, the effect of earlyenvironmental influences is clear (Fig. 1).
There are now many epidemiological studies(1–3) relating impaired fetal growth (deducedfrom birth weight or body proportions) to anincreased incidence of cardiovascular disease ortype 2 diabetes mellitus (T2D) or their precur-sors: dyslipidemia, impaired glucose tolerance,
or vascular endothelial dysfunction. Disease riskis higher in those born smaller who becomerelatively obese as adolescents or adults (1).Interpretation of these studies has led to debateabout the magnitude of the effect (4), althoughthe only published estimate based upon a long-term Finnish cohort (3) suggests it to be substan-tial. Prospective clinical studies on children bornsmall also provide support for the concept (6, 7).
In evaluating the relative role of genetic andenvironmental factors, it is useful to note that
birth size has only a small genetic componentand primarily reflects the quality of the intrauter-ine environment. The observed relationship be-tween disease risk and birth size does not implya causal role of being born small but reflects thesensitivity of fetal growth to adverse intrauterineinfluences. It is considered that it is the effect ofenvironmental influences acting during early de-velopment that is the causal trigger. Indeed, stud-ies reviewed below indicate that adverse devel-opmental influences can affect disease risk with-out birth size being affected. The term “maternalconstraint” encapsulates those environmentalfactors that influence birth size even in healthypregnancies, such as maternal size, age, parity,and multiple pregnancy, and various mecha-nisms limiting nutrient supply to the fetus (8).Firstborn offspring show a higher incidence oflow birth weight and increased obesity in child-hood and adolescence than their subsequent sib-lings (9). Although nutrition has received the
most focus (10–12), other early-environmental factors such as infec-tion, season of birth (13, 14), andsmoking (15) may have long-termeffects.
There is now evidence for suchdevelopmental influences in an in-creasingly wide range of chronicdiseases—osteoporosis (16), poly-cystic ovarian syndrome (17), mooddisorders (18), and psychoses (19).Much more research is needed inthese areas to establish the extent ofthe phenomenon unequivocally.Perhaps finding markers of earlygene-environment interactions willallow definitive clinical data to beobtained.
Studies of famine indicate thatthe longer-term effects on off-spring may depend on the dura-tion and timing of undernutrition
and can be independent of birth size (20, 21).Further, there is increasing evidence that fetaldevelopment can be affected by nutritionalvariation within the normal range of westerndiets (22), and unbalanced dieting by mothersin early pregnancy is common. In addition tothe embryonic and fetal periods, the postnatalenvironment and the infant phase may alsoplay a role. For example, both cognitive func-tion (23) and insulin secretion (24) in child-hood are influenced by the type of feeding in
1Liggins Institute, University of Auckland and Nation-al Research Centre for Growth and Development, 2-6Park Avenue, Grafton, Private Bag 92019, Auckland,New Zealand. 2Centre for Developmental Origins ofHealth and Disease, University of Southampton, Prin-cess Anne Hospital Level F (887), Coxford Road,Southampton S016 5YA, UK.
*To whom correspondence should be addressed.E-mail: [email protected]
Fig. 1. Data from 22,846 men older than 40 years of age showing strongrelationships between birth size and the relative risk of developingclinically significant hypertension or diabetes mellitus but no relationshipwith systolic blood pressure. These data demonstrate the importance ofstudying outcomes rather than surrogate measures of disease. Data arederived from G. C. Curhan et al. (2).
REVIEWS
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1733
the premature neonate, who is subjected tohigher fat intakes than are experienced inutero. Rapid weight gain and growth in in-fancy or childhood may be a further com-pounding factor, even when birth size is rel-atively normal (25–27).
Experimental StudiesExperimental evidence that the prenatal or peri-natal environment can influence adult postnatalphysiology is available in several mammalianspecies (12, 28). These studies demonstrate thatmanipulation of the periconceptual (29), em-bryonic, fetal, or neonatal (30) environment canlead to altered postnatal cardiovascular and/ormetabolic function. Although the environmen-tal triggering cues are not yet fully understood,most manipulations have been dietary and in-clude maternal pan-undernutrition (10, 31),low-protein diet (11),or high-fat (30, 32)diet. Furthermore, inthe normal nonma-nipulated pig (33) andguinea pig (31), in-verse relationships be-tween birth size andlater insulin sensitivi-ty, and blood pressureare reported. Maternalglucocorticoid admin-istration produceseffects similar tothose produced by un-dernutrition (34, 35).Undernutrition maysuppress placental 11-�-hydroxysteroid de-hydrogenase type 2,which inactivates cor-tisol and exposes thefetus to excess mater-nal steroid; however,induction of long-term effects can occurwell before the pla-centa is formed and independently of changesin glucocorticoid levels.
Environmental Effects viaDevelopmental Plasticity“Developmental plasticity” provides organismswith the ability to change structure and functionin response to environmental cues; these re-sponses usually operate during critical time win-dows and then become irreversible. Such plas-ticity permits a range of phenotypes to developfrom a single genotype in response to environ-mental cues. In Daphnia, helmet formation (adefensive, morphological change) is dependenton the early environment and risk of predation(36). In the locust, Locusta migratoria, the wingshape and metabolic pathways are determined inthe larval stage by pheromone signals indicat-ing population density (37). In the axolotl, early
environmental conditions determine whether themature form will be purely aquatic or amphibi-ous (38). Developmental plasticity sets the tem-plate on which continued postnatal homeostaticand homeorhetic [maintaining a time-dependentprocess, e.g., growth trajectory (39)] adaptationcan occur.
There are several mechanisms by which en-vironmental cues can influence the developmen-tal program (Fig. 2). First, they can exert effectsprior to implantation and affect gene expression,particularly by inducing epigenetic changes inthe DNA. In the agouti mouse mutant, maternaldietary folate supplementation at conception al-ters the expression of the imprinted agouti geneby altering the capacity for methylation (40). Inpregnant rats, giving an additional source ofdietary methyl groups prevents vascular defectsin the offspring, even if the diet is protein defi-
cient overall. Prolonged in vitro culture of theovine embryo affects later expression of theimprinted insulin-like growth factor–2 (IGF-2)system (41). Nonimprinted genes can also un-dergo epigenetic change in response to the envi-ronment—the choice of exon usage in the glu-cocorticoid receptor gene is altered both byprenatal glucocorticoids and neonatal behavioralmanipulation owing to changes in histone acet-ylation and DNA methylation in a transcriptionalfactor binding site (42). These changes persistthroughout life as manifested in altered hypotha-lamic-pituitary-adrenal (HPA) axis activity. In-triguingly, the effects could be reversed by ahistone deacetylase inhibitor, suggesting poten-tial reversibility. This finding may have broaderimplications.
Second, tissue differentiation may be al-tered. Prolonged in vitro culture of the rodent
or ruminant embryo affects the allocation ofblastocyst stem cells to inner cell mass ortrophectoderm lineages (29). This influencesthe relative growth trajectories of the placentaand fetus, thus affecting fetal development inlate gestation. Organ-specific effects are alsoreported. Fetal pancreatic islet cell differen-tiation is affected by maternal nutritional ma-nipulation, leading to altered developmentalapoptosis and expression of transcriptionalregulators of the Pdx and Pax gene families(43). Differential expansion of periportal andperivenous hepatocyte cell clones is re-ported after maternal nutritional or hormonalmanipulation and may lead to altered hepaticglucose and lipid metabolism (44). Maternaldietary (45) or glucocorticoid manipulation (46)in the rat reduces the number of renal glomeruliin the offspring. This “trade-off,” although it
conserves resources inthe short term, mayinduce later glomeru-lar hyperfiltration tomaintain fluid andelectrolyte homeosta-sis, and declining re-nal function with ageleads to progressivehypertension. Indeed,this concept of trade-offs between prenatalgrowth/developmentand postnatal growth/function may explainthe compounding roleof rapid postnatalgrowth in generatingadditional disease risk(26, 27).
Lastly, changesmay be induced inhomeostatic controlmechanisms. Defectsin both insulin secre-tion, as well as in in-sulin postreceptor ac-
tion (47) and glucose transporter function inmuscle, may predispose the individual to T2D.Vascular endothelial function is altered follow-ing maternal dietary manipulation (48), and thistissue is involved in controlling blood flow,clotting, inflammation, growth, and metabo-lism. Intrauterine environmental induction ofchanges in central nervous cardiovascular con-trol (49) is also reported.
These various prenatal changes may alter theoffspring’s response to the postnatal environment.In rat pups subjected to prenatal undernutrition,exposure to a postnatal high-fat diet has muchgreater effects on the development of obesity andhyperleptinemia than in pups born to mothers witha normal dietary intake, but then fed a high-fatdiet postnatally (10). Likewise, pigs exposed inutero to a high-fat diet have a different tolerance tohigh-fat diets postnatally (50).
Fig. 2. A general model of how intergenerational, genetic and environmental, and prenatal andpostnatal factors interact to create a pathway to altered disease risk in adulthood. If the prenataland postnatal environments match, the physiological settings achieved through the processes ofdevelopmental plasticity will leave the organism well prepared for the postnatal environment.Conversely, a mismatch between the prenatal and postnatal environment may be pathogenic.
R E V I E W S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1734
Types of Response to the EarlyEnvironmentSome responses of the embryo or fetus to itsenvironment may, however, be developmentallydisruptive with no adaptive value—examples areresponses to environmental teratogens. Howev-er, the fetus has many homeostatic and homeo-rhetic mechanisms that confer immediate surviv-al advantage—e.g., alterations in regional bloodflows and organ growth when nutrient or oxygensupply is reduced—even if there may be subse-quent postnatal costs. A further class of re-sponse, termed a predictive adaptive response(PAR) (28, 51), has been identified that appearsprimarily to have future adaptive value. For ex-ample, the coat of meadow vole offspring isthicker if offspring are born at a timeof decreasing day length than if theyare born in spring, even though theperinatal thermal environments aresimilar (52). It is proposed that PARsallow the developing organism to usedevelopmentally plastic processes toset its postnatal physiological pheno-type to one that it predicts will give itan optimal chance of survival to re-produce when an adult.
The responses to an environmen-tal exposure in one generation mayextend over several generations andare well recognized in comparativebiology as “maternal effects.” Theirpossible role in the developmental or-igins of disease has been recently re-viewed (53). For example, birth sizeis reduced in the offspring of womenwho themselves were fetuses duringtransient famine (54), and effects onblood pressure, endothelial function,and insulin sensitivity are passed to F2
offspring of undernourished pregnantrats (55). This might reflect eithertransgenerational passage of environ-mentally induced epigenetic change,as suggested by studies in the agoutimouse (40), or an effect on the repro-ductive tract of the F1 generation, assuggested from clinical studies ofgirls with intrauterine growth retarda-tion (56).
An Evolutionary PerspectiveThere have been several models proposed toexplain the changing demography of “life-style”diseases such as T2D. The “thrifty genotype”concept (57) proposed that populations havebeen selected for alleles favoring insulin resis-tance. Such “thrifty genes” confer advantage in apoor food/high energy expenditure environmentby reducing glucose uptake and limiting bodygrowth. When individuals of this genotype en-counter an environment of plentiful food/lowenergy expenditure, they are at risk of develop-ing T2D and the metabolic syndrome (58). Soalthough selection for these genes enabled our
ancestors to survive as hunter-gatherers, they putmodern humans at greater risk of disease, espe-cially as our longevity increases. Because insulinis a fetal growth factor, selection for such genesmight also induce lower birth weight (5). Forexample, mutation in the glucokinase gene pro-duces reduced fetal growth and later insulin re-sistance independently (59).
But purely genetic models cannot explainthe reported effects of human famine duringgestation (21) or the experimental animalstudies. The alternate “thrifty phenotype”model (60) posits that the fetus becomesgrowth retarded in response to adverse envi-ronmental conditions in utero, and the asso-ciated adaptations induce a phenotype better
suited to a deprived postnatal food/energyenvironment. However, this model does noteasily account for the graded effects on dis-ease risk seen across the normal birth weightrange (1, 2), or the way in which the disparitybetween the prenatal and postnatal environ-ment determines the level of risk.
Recent work stresses that both genetic andenvironmental factors must be involved.Studies of a polymorphism in the PPAR�2gene (which codes for a transcription factoraffecting gene expression involved in thecontrol of insulin sensitivity) associated withincreased risk of T2D show that the polymor-phism is only associated with a higher risk ofT2D if birth weight is reduced (61). Clearly,
the relationship between birth size and dis-ease risk cannot be explained by independenteffects on insulin sensitivity and fetal growth.Another example is polymorphisms of thevitamin D receptor, the effect of which is thatthe risk of osteoporosis is influenced by birthsize (16).
These various models lead to a more generalsynthesis (28, 51) (Fig. 3). Developmental re-sponses to environmental stimuli may be eitherdisruptive or adaptive. The former have no evo-lutionary significance. For the latter, the advantageneed not be immediate, but may arise from a PARmade in expectation of the future environment.Such PARs are made during the phase of devel-opmental plasticity to optimize the phenotype for
the probable environment of the ma-ture organism, and epigenetic changeis likely to be the mechanistic basis(51). Where there is a match betweenthe predicted and actual mature envi-ronment, these PARs are appropriateand assist survival. Conversely, inap-propriate predictions increase the riskof disease. Modeling suggests thatsuch lagged responses aid the survivalof a species (62).
Longevity was short in ances-tral hominids, and thus little nega-tive selection pressure has operatedto limit the adverse consequencesof a strategy now manifest inmodern humans as disease inmiddle age. However, recent stud-ies charting demographic trends inlongevity (63) show that such ef-fects are of increasing importance.It appears that evolution has pre-served genes encoding mechanismsthat allow the organism to mountPARs. A key element of this modelis that it focuses on the relativeenvironmental state between theplastic and mature phases. There-fore, because of intrauterine con-straint, even when fetal growthfalls within the normal range, beingborn into an enriched postnatal en-vironment can create a mismatch.
This model, thus, encompasses both the evi-dence focusing on embryonic/fetal cues (1,21, 29) and infant/childhood cues (24, 26).The importance of the relative nature of theenvironments in the plastic versus maturephase is demonstrated by the observation thatin mice, merely giving adequate postnatalnutrition reduces longevity in prenatally de-prived offspring (64).
Relevance to Patterns of DiseaseThe intrauterine environment cannot changedramatically between generations (51). But inmany societies, high-calorie food is nowplentiful and the energy expenditure has be-come reduced. Thus, the potential for dispar-
Fig. 3. The red lines show the upper and lower limits of the environ-mental range (for example, nutrition) to which the mature organismcould be exposed. The PARs model proposes that the developingorganism growing optimally (left side) adjusts its physiology to beappropriate for its predicted mature environmental range (shadedarea). If the early environment is impaired (toward right side), thenthe range of environments for which the organism is adapted by PARswill not match the mature environment. This mismatch means thatthe organism is likely to have a physiology inappropriate for theenvironment in which it is now living (space between the shade areaand upper red line). In modern humans, such a mismatch leads to arisk of disease. This scenario is common in the developing worldwhere fetal growth is often constrained by small maternal size,maternal disease, and poor nutrition and where postnatal food avail-ability is increasing. Because the upper limit of the nutritional envi-ronment is rising globally, the risk of disease due to mismatchincreases even for individuals who had normal early development.
R E V I E W S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1735
ity between pre- and postnatal environmentsis increasing. In some developing societies,the postnatal food-energy environment hasdramatically changed even within a genera-tion, but fetal growth is still markedly con-strained; this may explain the rapid increasein the incidence of T2D seen in such popu-lations (25).
The experimental and prospective clinicalstudies add weight to the epidemiologicaldata and suggest that early development doeshave significant echoes in disease riskthroughout life. There is a growing awarenessof the potential for epigenetic change to playa role in disease generation. A key issue is therelative importance of early-life events ininforming interventional strategies during hu-man development versus those instituted inadult life. If appetite, food choice, and exer-cise propensity are partially induced duringearly development as in experimental animals(30, 65), then postnatal life-style interven-tions may be less effective than hoped. Itseems that increasing awareness of the needto promote the health and nutrition of femalesof reproductive age is one important elementfor the prevention of chronic disease in futuregenerations across the globe.
References and Notes1. D. J. P. Barker, Ed., Fetal Origins of Cardiovascular and
Lung Disease (Dekker, New York, ed. 1, 2001).2. G. C. Curhan et al., Circulation 94, 3246 (1996).3. D. J. P. Barker, J. G. Eriksson, T. Forsen, C. Osmond, Int.
J. Epidemiol. 31, 1235 (2002).4. R. Huxley, A. Neil, R. Collins, Lancet 360, 659 (2002).5. A. T. Hattersley, J. E. Tooke, Lancet 353, 1789 (1999).
6. P. L. Hofman et al., J. Clin. Endocrinol. Metab. 82, 402(1997).
7. C. P. Leeson et al., Circulation 96, 2233 (1997).8. P. D. Gluckman, M. A. Hanson, Semin. Neonatol., in press.9. K. K. Ong,M. Preece, P.M. Emmett,M. L. Ahmed, D. B.
Dunger, Pediatr. Res. 52, 863 (2002).10. M. H. Vickers, B. H. Breier, W. S. Cutfield, P. L.
Hofman, P. D. Gluckman, Am. J. Physiol. 279, E83(2000).
11. S. Langley-Evans, A. A. Jackson, Clin. Sci. 86, 217 (1994).12. C. E. Bertram,M. A. Hanson, Br. Med. Bull. 60, 103 (2001).13. G. Doblhammer, J. W. Vaupel, Proc. Natl. Acad. Sci.
U.S.A. 98, 2934 (2001).14. D. A. Lawlor, G. Davey Smith, R. Mitchell, S. Ebrahim,
Heart 90, 381 (2004).15. C. Power, B. J. Jefferis, Int. J. Epidemiol. 31, 413 (2002).16. E. M. Dennison et al., Paediatr. Perinat. Epidemiol. 15,
211 (2001).17. L. Ibanez, C. Valls, N. Potau, M. V. Marcos, F. de
Zegher, Clin. Endocrinol. 55, 667 (2001).18. C. Thompson, H. Syddall, I. Rodin, C. Osmond, D. J. P.
Barker, Br. J. Psychiatry 179, 450 (2001).19. K. Wahlbeck, T. Forsen, C. Osmond, D. J. P. Barker,
J. G. Eriksson, Arch. Gen. Psychiatry 58, 48 (2001).20. V. Kannisto, K. Christensen, J. W. Vaupel, Am. J.
Epidemiol. 145, 987 (1997).21. T. J. Roseboom et al., Mol. Cell. Endocrinol. 185, 93 (2001).22. K. Godfrey, S. Robinson, D. J. Barker, C. Osmond, V.
Cox, Br. Med. J. 312, 410 (1996).23. A. Lucas, R.Morley, T. J. Cole, Br. Med. J. 317, 1481 (1998).24. A. Singhal, M. Fewtrel, T. J. Cole, A. Lucas, Lancet 361,
1089 (2003).25. C. H. D. Fall, Ind. Pediatr. 40, 480 (2003).26. J. G. Eriksson, T. Forsen, J. Tuomilehto, C. Osmond,
D. J. Barker, Br. Med. J. 322, 949 (2001).27. A. Singhal, J. Wells, T. J. Cole, M. Fewtrell, A. Lucas,Am. J. Clin. Nutr. 77, 726 (2003).
28. P. D. Gluckman, M. A. Hanson, Trends Endocrinol.Metab. 15, 183 (2004).
29. W. Y. Kwong, A. E. Wild, P. Roberts, A. C. Willis, T. P.Fleming, Development 127, 4195 (2000).
30. A. Plagemann et al., Brain Res. 836, 146 (1999).31. K. L. Kind et al., Am. J. Physiol. 284, R140 (2003).32. I. Y. Khan et al., Hypertension 41, 168 (2003).33. K. R. Poore, A. L. Fowden, Diabetologia 47, 340 (2004).34. M. Dodic, C. N.May, E.M.Wintour, J. P. Coghlan, Clin.
Sci. 94, 149 (1998).
35. J. R. Seckl, Steroids 62, 89 (1997).36. A. A. Agrawal, C. Laforsch, R. Tollrian, Nature 401, 60
(1999).37. S.W. Applebaum, Y. Heifetz, Annu. Rev. Entomol. 44,
317 (1999).38. M. J. West-Eberhard, Developmental Plasticity and
Evolution (Oxford Univ. Press, New York, ed. 1, 2003).39. C. H. Waddington, The Strategy of the Genes. A
Discussion of Some Aspects of Theoretical Biology(Allen & Unwin, London, 1957).
40. C. A. Cooney, A. A. Dave, G. L. Wolff, J. Nutr. 132,2393S (2002).
41. L. E. Young et al., Nat. Genet. 27, 153 (2001).42. I. C. Weaver et al., Nat. Neurosci. 7, 847 (2004).43. A. L. Fowden, D. J. Hill, Br. Med. Bull. 60, 123 (2001).44. M. Desai, N. J. Crowther, E. Ozanne, A. Lucas, C. N.
Hales, Biochem. Soc. Trans. 23, 331 (1995).45. S. C. Langley-Evans, S. J. Welham, A. A. Jackson, Life
Sci. 64, 965 (1999).46. C. E. Bertram, M. A. Hanson, Reproduction 124, 459
(2002).47. S. E. Ozanne et al., J. Endocrinol. 177, 235 (2003).48. L. Brawley et al., J. Physiol. 554, 497 (2004).49. D. I. Phillips, D. J. Barker, Diabet. Med. 14, 673 (1997).50. J. F. Norman, R. F. LeVeen, Atherosclerosis 157, 41 (2001).51. P. D. Gluckman, M. A. Hanson, The Fetal Matrix:
Evolution, Development, and Disease (CambridgeUniv. Press, Cambridge, ed. 1), in press.
52. T. M. Lee, I. Zucker, Am. J. Physiol. 255, R831 (1988).53. A. J. Drake, B. R.Walker, J. Endocrinol. 180, 1 (2004).54. L. H. Lumey, Paediatr. Perinat. Epidemiol. 6, 240 (1992).55. C. Torrens et al., 543.P, 41P (2002)56. L. Ibanez, N. Potau, G. Enriquez, F. de Zegher, Pediatr.Res. 47, 575 (2000).
57. J. V. Neel, Am. J. Hum. Genet. 14, 353 (1962).58. A. Lev-Ran, Diabet. Metabol. Res. Rev. 17, 347 (2001).59. A. T. Hattersley et al., Nat. Genet. 19, 209 (1998).60. C. N. Hales, D. J. Barker, Br. Med. Bull. 60, 5 (2001).61. J. G. Eriksson et al., Diabetes 51, 2321 (2002).62. E. Jablonka et al., Philos. Trans. R. Soc. London B Biol.
Sci. 350, 133 (1995).63. J. W. Vaupel et al., Science 280, 855 (1998).64. S. E. Ozanne, C. N. Hales, Nature 427, 411 (2004).65. M. Vickers, B. H. Breier, D. McCarthy, P. Gluckman,Am. J. Physiol. 285, R271 (2003).
66. M.A.H. is supported by the British Heart Foundation. Wethank C. Pinal for her assistance on the manuscript.
Inflammatory Exposure and Historical Changesin Human Life-Spans
Caleb E. Finch* and Eileen M. Crimmins
Most explanations of the increase in life expectancy at older ages over history emphasize theimportance of medical and public health factors of a particular historical period. We proposethat the reduction in lifetime exposure to infectious diseases and other sources of inflam-mation—a cohort mechanism—has also made an important contribution to the historicaldecline in old-age mortality. Analysis of birth cohorts across the life-span since 1751 inSweden reveals strong associations between early-age mortality and subsequent mortalityin the same cohorts. We propose that a “cohort morbidity phenotype” represents inflam-matory processes that persist from early age into adult life.
A long-term decline in mortality, be-ginning before 1800 in some coun-tries in Northern Europe, has resulted
in a 50% increase in adult life expectancy (1,2). Childhood mortality has decreased by90%, and this has been attributed mainly to adecreased incidence of infectious disease (2–
4). After 1850, older-age mortality declined,with greater improvement in recent decades(1, 5). Most explanations of the long-termdecline in mortality have focused on im-provements in sanitation, nutrition, income,and medicine. We develop the specific hy-pothesis that decreased inflammation during
early life has led directly to a decrease inmorbidity and mortality resulting from chron-ic conditions in old age.
Our argument is supported by recentresearch linking an individual’s exposure topast infection to levels of chronic inflam-mation and to increased risk of heart attack,stroke, and cancer. For example, the risk ofheart attack and stroke is correlated withserum levels of inflammatory (acute phase)proteins such as C-reactive protein (CRP)(6–8). Within individuals, CRP levels are
Andrus Gerontology Center and Departments of Bio-logical Sciences and of Sociology, University of South-ern California, Los Angeles, CA 90089, USA.
*To whom correspondence should be addressed.E-mail: [email protected]
R E V I E W S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1736
also correlated to the number of seroposi-tivities to common pathogens, indicating ahistory of infections (7, 8). Furthermore,drugs with anti-inflammatory activities[nonsteroidal anti-inflammatory drugs(NSAIDs), statins] reduce the risk of vas-cular events and possibly Alzheimer’s dis-ease (9, 10), implying links between thelevels of inflammation and major chronicconditions important in old age.
Links Between Health in Early Life andin Later LifeMuch evidence links early-life infectionswith later morbidity, including cardiovascu-lar and respiratory disease, cancer, and dia-betes. Some infections directly cause organdamage; the classic example is rheumaticheart disease, which increases adult morbid-ity from heart valve damage incurred fromchildhood streptococcal infections (11). Thepresence of early-life infections has also beenassociated with late-life chronic disease andmortality, as shown in many examples fromearly to recent times. In rural 18th-centurySweden, greater exposure to infections dur-ing infancy was associated with higher old-age mortality (12). Among U.S. Civil Warveterans, infectious disease in early adult-hood was associated with heart and respira-tory problems after age 50 (13). Moreover,respiratory infections in early life were asso-ciated with later lung impairments (12, 14).Adult cardiovascular disease has also beenassociated with cohort levels of infant diar-rhea and enteritis (15). Among Americanscurrently in their 50s, those who experiencedmajor childhood illness are 15% more likelyto report having cardiovascular conditionsand twice as likely to have cancer or chroniclung conditions (16). Finally, declining infec-tion during the 20th century has been estimat-ed to explain 11 to 24% of the reduction inlate-life morbidity and mortality (13).
These associations between early andlater morbidity and mortality imply cohort-specific effects on adult mortality trends,especially in old age when vascular condi-tions and cancer dominate mortality. Co-hort effects could arise from the commonepidemiological environments that mem-bers of a particular birth cohort experiencein their younger lives. Thus, changes in theepidemiological environment that occurwithin a given historical period would af-fect surviving members of cohorts for therest of their lives. Enduring effects of earlyenvironment, even if conditions improvedat later periods, could be designated as a“cohort morbidity phenotype.”
As early as 1934, Kermack et al. (17)noticed that as mortality at younger agesimproved in successive cohorts in Englandand Sweden, the adult survivors in those co-horts also had lower mortality. From this they
hypothesized that maternal health and childenvironment were major determinants ofhealth at later ages, or that the mortalitycharacteristics of a cohort persisted through-out its life-span. In 1956, Jones (11) devel-oped further links between cohort mortality atyounger and older ages in Swedish 18th- and19th-century populations by examining mor-tality rates over the life-span. Although infantmortality was not then available for cohortsborn before 1895, Jones concluded that birthcohorts had parallel mortality curves acrossthe adult ages and that mortality curvesacross the life-span were displaced to lowervalues in more recent cohorts. He hypothe-sized that “the physiological age of each newgeneration is remaining more youthful at thesame chronological age” (11). This is an im-portant observation, because most biologistsand demographers examining mortalitychange over time at older ages have concen-trated on adult mortality.
With the longer data series now availablefor Sweden, we have updated Jones’ obser-vations, graphing age-specific mortality ratesfor five birth cohorts from 1751 to 1940 (Fig.1A). The age-specific mortality across thelife-span shows progressive downshifts inage-specific mortality for later-born cohorts.Mortality at any given age across the life-span is lower in successive cohorts. Thus,cohorts with lower young-age mortality alsohave lower mortality at any given age in laterlife, consistent with Jones’ hypothesis.
The cohort analysis also reveals that themajor declines in mortality have had littleeffect on the basic rate of mortality acceler-ation during aging, as shown for cohorts byparallel linear slopes of mortality on semi-logarithmic plots (Fig. 1A). Data from mosthuman populations show regular relation-ships of mortality at one adult age to mortal-ity at the preceding age and subsequent ages,in which mortality accelerates more or lesssmoothly during adult life up to the oldestages, with a characteristic “Gompertz slope”(18). The present cohort data show that majorimprovements in human environments,which lowered overall mortality by as muchas 90%, have not altered the characteristicmortality acceleration during aging. Eventransient adversity may shift the line upward,without change in slope (18). These progres-sive reductions in mortality are more resolvedwhen plotted as cohorts rather than as con-ventional plots of period age-specific mortal-ity over time (Fig. 1B). The similarity ofmortality slopes at the older ages observed inthe cohort plots is not found in period age-specific mortality curves, which tend to con-verge at older ages.
Using the Swedish data for individualages during childhood and old age for per-sons born in each year from 1751 to 1927, wecan further develop two points presaged by
Kermack et al. (17) and Jones (11): (i) thatthe historical mortality decline among the oldand young begins in the same cohort, and (ii)that infant mortality has a stronger relation-ship to later-life mortality than does mortalityin subsequent childhood years. Examinationof annual trends in childhood and old-agemortality for cohorts born from 1751 to 1927indicates that declines in mortality after age70 tend to lag about 70 years behind those forinfants (19). When we relate childhood mor-tality to later-age mortality for Swedish birthcohorts born in the 177-year period from1751 to 1927, we find strong relationshipsbetween rates of childhood mortality andmortality for cohort survivors in old age.Most variance in the 177-year series of old-age mortality for cohorts was explained bymortality before age 10. Moreover, the annu-alized effect of each childhood year on old-age mortality is three times as great for infantmortality than for mortality in subsequentchildhood years. This confirms the greatereffect of infant versus childhood mortality onold-age mortality observed in a small, ruralSwedish region (12).
Adult Disease, Infection, andInflammationWe hypothesize that chronic inflammatorymechanisms drive much of the influence ofearly-life infections on later morbidity andmortality. As noted above, in contemporarypopulations, serological indicators of infec-tion and inflammatory indicators are relatedto vascular disease and many other morbidi-ties of aging. Markers of inflammation in-clude elevations of blood CRP as well asinterleukin-6, tumor necrosis factor–�, andfibrinogen (components of the acute phaseinflammatory response). Such inflammatoryresponses can be induced by invading patho-gens, as well as by trauma or internal tissueinjury. Infections may be local agents in vas-cular disease, whereas asymptomatic arteriallesions (which are ubiquitous at early ages)appear to progress through inflammatory pro-cesses (20). Atheromas contain macrophagesand other cells that secrete inflammatory pro-teins, which, if chronically elevated, may bein themselves pathogenic rather than simplyindicators of risk. CRP, for example, canactivate the complement system and increaselow-density lipoprotein uptake by macro-phages (6). Thus, adaptive responses to short-term infections or injury can become mal-adaptive in the long term—a double-edgedsword that evolutionary biologists refer to asantagonistic pleiotropy.
In the past, substantial proportions of pop-ulations in countries that now have low mor-tality suffered conditions that chronically el-evate inflammatory markers. Among popula-tions that still have relatively high mortality,these conditions remain highly prevalent. For
R E V I E W S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1737
instance, many people living in relativelyhigh-mortality conditions contract chronic tu-berculosis, diarrheas, and parasite-borne dis-eases such as malaria that persistently elevateblood CRP, as observed in tuberculosis (21)and infections of Escherichia coli and Heli-cobacter pylori (22). These associations ofCRP with infections suggest that the histori-cal decline in infections would have loweredexposure to CRP and other inflammatory pro-teins. H. pylori is an instructive example.
This common bacterium is the major cause ofpeptic ulcers but is also associated with cor-onary disease (23). H. pylori infections areusually acquired in childhood and persistthroughout life. In the past, many if not mostindividuals in what are now low-mortalitycountries carried H. pylori, but because ofimproved public health and hygiene, infec-tions have declined. For example, H. pyloriinfections decreased by a factor of 6 in birthcohorts of the Bristol Helicobacter Project
(24). Periodontal disease, another source ofchronic inflammation, was highly prevalentbut has now declined with the introduction ofdental hygiene in countries with currentlylow mortality. Periodontal disease has beenassociated with chronically high levels ofCRP and possibly heart disease (24). Theseand other examples suggest that public healthand medical interventions have led to a lowerlevel of diverse infections, which in turn hasresulted in reduced inflammation throughoutlife in modern populations. Thus, the factorsthat reduce mortality within specific histori-cal periods have also resulted in reductions inlifetime levels of inflammation and old-agemortality within cohorts.
The Role of Nutrition?Malnutrition at early ages, including in ute-ro, is also hypothesized to influence later-life morbidity and mortality (2, 25). The“fetal origins” hypothesis of Barker et al.(26) associates low birth weight with ma-ternal malnutrition, leading to higher mor-bidity at later ages from cardiovascular dis-ease, hypertension, and type 2 diabetes.Attenuated fetal growth is thought to im-pair organ and vascular development and toalter metabolic set points. Not all evidencesupports an exclusive role of malnutritionin the fetal-origins hypothesis. For exam-ple, maternal infections from diseases suchas tuberculosis, which was common untilwell into the 20th century, also impair fetalgrowth (2, 4, 12). Moreover, the famine inrural Finland from 1866 to 1868 tripleddeath rates at 0 to 9 years but did not alterthe survivors’ life-spans (27).
We would argue that the inflammatory-infection and nutrition hypotheses are notcompeting but complementary in linkingtwo mechanisms of morbidity in early andlater life: Even well-fed babies are vulner-able to rampant infections, and infectionsalone can cause malnutrition and later de-ficiencies. Childhood diarrheas, for exam-ple, impair cardiac muscle synthesis (28),which could underlie associations of infantdiarrhea with later cardiovascular disease(16). Slowed infant growth in the Barkerhypothesis (26) could thus be consequent toinfections that cause inflammatory respons-es as well as impair nutrient absorption.Using historical Swedish cohorts to testboth hypotheses, Bengtsson and Lindstrom(12) concluded that the level of infectionamong infants had a stronger influence thanfood availability on later-life mortality andlife expectancy, and they implicated respi-ratory mechanisms. In addition, we suggestthat the systemic inflammatory processesrecognized in modern populations are im-portant as risk factors in vascular disease.
Early-life infection may also explain ef-fects of the season of birth on longevity.
gni
yd
noitr
op
orp
la
un
nA
0.0001
0.001
0.01
0.1
1
0 9-5
91-
51
92-
52
93-
53
94-
54
95-
55
96 -
56
97-
57
98-
58
Age
1751-601811-201871-801901-101931-40
Period mortality
A
gni
yd
noitr
op
orp
la
un
nA
B
0.0001
0.001
0.01
0.1
1
0 9-5 -
51
91 -
52
92 -
53
93 -
54
94 -
55
95 -
56
96 -
57
97 -
58
98
Age
1751-60 1811-20 1871-80 1901-10 1931-40
Cohort mortality
Fig. 1. Age-specific mortality over the life-span, Sweden, 1751 to 1940 (semi-logarithmic plots).Data source: Berkeley Mortality Database. (A) Cohort mortality for persons born in the specifiedyears. (B) Period mortality occurring in the specified years. Mortality is estimated for the lateryears of the last birth cohort, assuming that mortality at adjacent age groups has the samerelationship as that in the prior cohort, and is represented by a dotted line.
R E V I E W S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1738
Among birth cohorts of the 19th and early20th centuries from Northern Europe, thoseborn in the spring eventually lived 3 to 6months longer than autumn births, with cor-responding differences in some later-life dis-eases (26). Although seasonal variations innutrition were emphasized, we would alsosuggest a role of inflammation.
ConclusionsLong-term declines in mortality for cohortsborn in Sweden from the middle of the 18thcentury into the 20th reveal important linksbetween mortality in old age and in early life.Cohort levels of mortality during childhoodare related to cohort mortality in old age,which implies an imprint of early exposureson the cohort morbidity phenotype. Thus,improved public health conditions and med-ical interventions have both immediate andlong-term benefits: a reduction in currentmortality combined with the enduring effectsof an improved early environment. Our argu-ment implies that mortality in later-born co-horts should be lower over the entire life-span. Although infection and inflammationare particularly elevated in childhood wheninfections are very prevalent, chronic infec-tions and lifelong inflammation should char-acterize all ages in populations with highinfectious mortality.
Improved childhood health and survivalalong with reduced chronic infections andinflammation are attributed to improved pub-lic health, medical advances, and an im-proved standard of living. The links betweenyoung- and old-age mortality help to explainthe widespread recent declines in old-agemortality and to anticipate further declines in
populations where declines of early-age mor-tality have more recently appeared. The rapiddecline in old-age mortality in developedcountries that began in the latter part of the20th century took researchers by surprise.Because few medical breakthroughs occurredbefore the onset of the decreased mortalityfrom heart disease and stroke in the 1960s,this decline is generally attributed to lifestylechange and medical advances (29). Accord-ing to our hypothesis, these improvements inpart originated as cohort effects from reducedearly morbidity.
The stability of cohort mortality slopes(Gompertz slope), despite the remarkablevariability of overall mortality (Fig. 1A) (18),implies that future increases in life expectan-cy from reduced inflammatory causes may berelatively small, particularly in populationsthat have had low levels of childhood infec-tion for many decades and now may be ap-proaching a lower limit. These findings frommany fields suggest that inflammatory pro-cesses that influence the outcomes of agingcan be kindled or quenched by exposure toextrinsic infections, inflammatory stimuli,and nutrition. A new theory of human healthin life history could emerge from a fulleraccounting of inflammatory exposures fromgestation to old age.
References and Notes1. J. Oeppen, J. W. Vaupel, Science 296, 1029 (2002).2. J. C. Riley, Rising Life Expectancy: A Global History
(Cambridge Univ. Press, New York, 2001).3. R. Floud, K.Wachter, A. Gregory, Eds., Height, Health,and History (Cambridge Univ. Press, New York, 1990).
4. I. T. Elo, S. H. Preston, Popul. Index 58, 186 (1992).5. J. R. Wilmoth et al., Science 289, 2366 (2000).
6. J. T.Willerson, P. M. Ridker, Circulation 109 (suppl. 1),II2 (2004).
7. J. Zhu et al., Am. J. Cardiol. 85, 140 (2000).8. J. L. Georges et al., Am. J. Cardiol. 92, 515 (2003).9. J. C. Breitner, Lancet Neurol. 2, 527 (2003).
10. A. H. Vagnucci Jr., W. W. Li, Lancet 361, 605 (2003).11. H. Jones, Adv. Biol. Med. Phys. 4, 281 (1956).12. T. Bengtsson, M. Lindstrom, Int. J. Epidemiol. 32, 286
(2003).13. D. L. Costa, Demography 37, 53 (2000).14. S. O. Shaheen et al., Am. J. Respir. Crit. Care Med.
149, 616 (1994).15. C. Buck, H. Simpson, J. Epidemiol. Community Health
36, 27 (1982).16. D. L. Blackwell, M. D. Hayward, E. M. Crimmins, Soc.
Sci. Med. 52, 1269 (2001).17. W. O. Kermack, A. G. McKendrick, P. L. McKinlay,
Lancet i, 698 (1934).18. C. E. Finch, M. C. Pike, M. Witten, Science 249, 902
(1990).19. E. M. Crimmins, C. E. Finch, unpublished data. A
regression analysis of early mortality associationswith later mortality by cohort versus period, forSweden and other countries, shows the overall pat-tern summarized here for Sweden.
20. W. Palinski, C. Napoli, FASEB J. 16, 1348 (2002).21. S. D. Lawn et al., Int. J. Tuberc. Lung Dis. 4, 340
(2000).22. A. M. Cadwgan et al., J. Infect. 41, 159 (2000).23. R. F. Harvey et al., Q. J. Med. 95, 519 (2002).24. K. M. Kolltveit, L. Tronstad, I. Olsen, Clin. Microbiol.Rev. 13, 547 (2000).
25. G. Doblhammer, J. W. Vaupel, Proc. Natl. Acad. Sci.U.S.A. 98, 2934 (2001).
26. D. J. Barker, Trends Endocrinol. Metab. 13, 364(2002).
27. V. Kannisto, K. Christensen, J. W. Vaupel, Am. J.Epidemiol. 145, 987 (1997).
28. R. J. Hunter et al., J. Nutrit. 131, 1513 (2001).29. P. A. Sytkowski, W. B. Kannel, R. B. D’Agostino,
N. Engl. J. Med. 322, 1635 (1990).30. We thank A. Hagedorn and R. Vejella for data analysis
and graphics, and B. Henderson, V. Longo, B. Teter,and A. Watts for helpful comments. Supported byNational Institute on Aging (NIA) grants AG13499,AG05142, and AG14751 and the Alzheimer’s Associ-ation (C.E.F.) and by NIA grant AG17265 (E.C.). C.E.F.is co-founder, stockholder, and member of the sci-ence advisory board of Acumen Pharmaceuticals Inc.,which is developing treatments for Alzheimer’sdisease.
R E V I E W S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1739
NEED HUMAN SPECIMENSFOR RESEARCH?NEED
HUMAN SPECIMENSFOR RESEARCH?The NCI Cooperative Human TissueNetwork (CHTN) provides normal,benign, pre-cancerous and canceroushuman tissue to the scientific commu-nity for basic and developmentalstudies in many areas of cancerresearch. Tissue micro-arrays are alsoavailable. Contact the CHTN websiteat: http://www-chtn.ims.nci.nih.gov, or1-866-GO2-CHTN (1-866-462-2486).
The NCI Cooperative Breast CancerTissue Resource (CBCTR) canprovide access to formalin-fixed,paraffin-embedded primary breastcancer specimens, with associatedpathology and clinical data. Thecollection is particularly well suitedfor validation studies of diagnostic andprognostic markers. The CBCTR alsohas breast cancer tissue micro-arraysdesigned to provide high power forstudies of stage specific markers.Contact the CBCTR website at: http://www-cbctr.ims.nci.nih.gov, or Ms.Sherrill Long, Information Manage-ment Services, Inc., (301) 984-3445;e-mail: [email protected].
The AIDS and Cancer SpecimenResource (ACSR) providesqualified researchers with tissue, cell,blood and fluid specimens, as well asclinical data from patients withAIDSand cancer. The specimens andclinical data are available for researchstudies, particularly those that translatebasic research findings to clinicalapplication. Contact theACSRwebsite at:http://acsb.ucsf.edu, orDr. Jodi Black, (301) 402-6293;e-mail: [email protected].
The Breast, Ovarian andColorectal Cancer FamilyRegistries (CFRs) includestwo international registries: theCancer Family Registry forBreast Cancer Studies (BreastCFR) and the Cancer FamilyRegistry for Colorectal CancerStudies (Colon CFR). TheBreast CFR provides familyhistory information, biologicalspecimens and epidemiologicand clinical data from clinic-based and population-basedfamilies at risk for breast andovarian cancers. The BreastCFR infrastructure is particu-larly suited to support interdis-ciplinary and translationalbreast cancer research. Simi-larly, the Colon CFR collectionincludes family history informa-tion, epidemiologic and clinicaldata, and related biologicalspecimens from individualswith colorectal cancer and theirfamilies. The Colon CFR is aresource for population andclinic-based, translationalresearch in the genetic epidemi-ology of colorectal cancer.Contact the CFRs website athttp:// epi.grants.cancer.gov/CFR/.
The NCI Cooperative ProstateCancer Tissue Resource(CPCTR) can provide access toover 4,000 cases of formalin-fixed, paraffin-embeddedprimary prostate cancer speci-mens, with associated pathologyand clinical data. Fresh-frozentissue is also available withlimited clinical follow upinformation. In addition, slidesfrom prostate cancer tissuemicro-arrays with associatedpathology and clinical data arenow available. Contact theCPCTR website at: http://www.prostatetissues.org, or Mr.Steve Marroulis, InformationManagement Services, Inc.,(301) 680-9770; e-mail:[email protected].
The NCI Clinical Trials Coop-erative Groups have bankedtumor specimens from largenumbers of uniformly treatedcancer patients with a variety ofmalignancies. Each group has areview process for researchproposals. If proposals receivefavorable reviews, specimenswith clinical, treatment andoutcome data can be madeavailable to researchers throughcollaborative arrangements.These banked specimens aremost useful for clinical correla-tive studies on uniformly treatedpatient populations. Contact theNCI Specimen Resource Locatorwebsite at: http://www.cancer.gov/specimens, or the NCITissue Expediter,e-mail: [email protected];(301) 496-7147.
Each of the resources listed above has an established review process for specimen requests and/or require-ments that must be met for access to specimens. Additional details may be obtained from the resourcewebsites and/or resource contacts.
The NCI Specimen Resource Locator is a web-based database to help researchers locate appropriate sourcesof normal, benign, pre-cancerous and cancerous human tissue specimens for cancer research, http://www.cancer.gov/specimens.
Other human specimen resources, including a variety of tissue micro-arrays, are also available. Contact theNCI Tissue Expediter, (301) 496-7147; e-mail: [email protected].
Direct Sub-Angstrom Imaging ofa Crystal Lattice
P. D. Nellist,1 M. F. Chisholm,2 N. Dellby,1 O. L. Krivanek,1
M. F. Murfitt,1 Z. S. Szilagyi,1 A. R. Lupini,2 A. Borisevich,2
W. H. Sides Jr.,2 S. J. Pennycook2*
Achieving sub-angstrom imaging has beena long-standing goal for electron microsco-py. Improved resolution allows not only awider range of materials to be imaged, butalso allows each material to be imaged inseveral possible orientations. It providesmuch improved sensitivity to atomic ar-rangements at defects and interfaces, downto the single-atom level for the first time insome instances. Sub-angstrom informationtransfer can be accomplished in an uncor-rected transmission electron microscope(TEM) with tilted illumination (1), but theinformation in the images becomes ex-tremely delocalized and the increased in-formation transfer is only in the direction ofthe tilt. Underfocusing the main imaginglens can also partiallycompensate for the ex-istence of spherical aber-ration (2), but the imagesrecorded are similarlyhighly delocalized andcontain low signal strength.Postprocessing of focal-series data can overcomesome of these limitations(3, 4). However, this is notdirect imaging because itrequires the collection ofmany images, and exten-sive processing of imagedata increases the risk ofthe introduction of imageartifacts. Previous evidenceof a sub-angstrom pointspread function from ascanning TEM (STEM),with apparent spots in aFourier transform and anintensity profile of a singleatom (5), is not unambigu-ous because such measure-ments are sensitive to er-rors due to noise, instabili-ties in the microscope, andincorrect adjustment of thedetector black level.
An indisputable testfor demonstrating sub-angstrom resolution is a
Si crystal observed in the [112] orientation,because it contains pairs of Si columns 78 pmapart. Figure 1, A and B, shows an imagerecorded with a VG Microscopes HB603U300-kV STEM fitted with a Nion aberrationcorrector. It was recorded in the annular dark-field (ADF) imaging mode. In a STEM, elec-tron optics focus a beam of electrons into anarrow spot, or probe, which is scanned overthe sample in a raster. The ADF detector’scollects electrons scattered by the sample toangles greater than the detector inner radius,which in this case was 0.0009 Gray (90mrad). Such high-angle scattering is largelyincoherent thermal diffuse scattering, whichmeans that the resolution observed in theimage is determined by the intensity distribu-
tion of the illuminating probe (2). Beforecorrection, without a large defocus, the opti-mum (Scherzer) resolution limit for ADF im-aging on this microscope was 0.13 nm. Theaddition of the corrector allows the probe-forming aperture to be opened up to give anexpected probe size in the range of 60 pm. InFig. 1, A and B, pairs of atomic columns canbe resolved with a spacing of 78 pm. TheFourier transform of this image (Fig. 1C)shows clear information transfer to 71 pm,and there is apparent lattice information at 61pm. We expect this spot to be weak, becauseat such a high spatial resolution, the physicalwidth of the atoms is substantial and reducesthe contrast between closely spaced columns.There is no evidence that the high-frequen-cy spots are due to incorrect background levelor distortions (6), and the simulated imageprofile compares well with the experimentaldata (Fig. 1D).
In summary, we have demonstrated directsub-angstrom resolution with an aberration-corrected STEM, an advance that allows ma-terials and nanostructures to be imaged with anew level of sensitivity. We expect light col-umns to be visible in the presence of adjacentheavy columns and individual dopant or im-purity atoms to be detectable within materi-als, at defects and interfaces, and on theirsurfaces. Such capability should enable a newunderstanding of the atomic-scale origins ofproperties with applications in the materials,chemical, and nanosciences.
References and Notes1. T. Kawasaki et al., Appl. Phys. Lett. 76, 1342 (2000).2. P. D. Nellist, S. J. Pennycook, Phys. Rev. Lett. 81, 4156
(1998).3. M. A. O’Keefe et al., Ultramicroscopy 89, 215 (2001).4. M. A. O’Keefe, E. C. Nelson, Y. C. Wang, A. Thust,
Philos. Mag. B 81, 1861 (2001).5. P. E. Batson, N. Dellby, O. L. Krivanek, Nature 418,
617 (2002).6. Materials and Methods are available as supporting
material on Science online.7. This research was sponsored by the Laboratory Di-
rected Research and Development Program of OakRidge National Laboratory (ORNL), managed by UT-Battelle LLC for the U.S. Department of Energy undercontract no. DE-AC05-00OR22725, and by an ap-pointment to the ORNL Postdoctoral Research Pro-gram administered jointly by ORNL and the OakRidge Institute for Science and Education.
Supporting Online Materialwww.sciencemag.org/cgi/content/full/305/5691/1741/DC1Materials and MethodsFigs. S1 and S2
1 June 2004; accepted 5 August 2004
1Nion Company, 1102 8th Street, Kirkland, WA98033, USA. 2Condensed Matter Sciences Division,Oak Ridge National Laboratory, Oak Ridge, TN37831–6030, USA.
*To whom correspondence should be addressed. E-mail: [email protected]
SimulationExperiment
804713
444
C
Fig. 1. (A and B) ADF images of Si[112] recorded with an aberration-corrected STEM. The image in (B) has been low-pass filtered to reducethe noise, and the small effects of image drift during the scan havebeen unwarped. (C) The modulus of the Fourier transform of theimage data and a profile through the spots enclosed by the box. The444 spacing (78 pm) corresponds to the smallest atomic columnspacing, and there is information transfer to the 713 (71-pm) spacingand weak transfer at the (804) 61-pm spacing. (D) An intensity profilethrough two column pairs in (A), formed by summing over a width of10 pixels. A simulated profile (6) is shown for comparison.
BREVIA
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1741
PROMEGA CORPORAT ION • www .p r o m e g a . c o m
©2004 Promega Corporation. 11567-AD-BK
������� ��� ����� ���� �� � �� �� ����� ������� �� �� ���� ��� ������ ��� ���
��� ����������������� � ��������� ������ ���� ���� ������ ���� � ������� ��� ���� ��� ��� �� �
��� ����� ��� �� ��� �������� ���� ��� ���� ������ ��� ��� ��� ��� ������� � �������
�� ��� ������ ��� ���� ������ �� ������� www.promega.com/myway
Customize.Exactly what you want.
Environmentally Induced ForegutRemodeling by PHA-4/FoxA and
DAF-12/NHRWanyuan Ao,1* Jeb Gaudet,1*† W. James Kent,2
Srikanth Muttumu,1 Susan E. Mango1‡
Growth and development of the Caenorhabditis elegans foregut (pharynx)depends on coordinated gene expression, mediated by pharynx defective (PHA)-4/FoxA in combination with additional, largely unidentified transcription fac-tors. Here, we used whole genome analysis to establish clusters of genesexpressed in different pharyngeal cell types. We created an expectation max-imization algorithm to identify cis-regulatory elements that activate expressionwithin the pharyngeal gene clusters. One of these elements mediates theresponse to environmental conditions within pharyngeal muscles and is rec-ognized by the nuclear hormone receptor (NHR) DAF-12. Our data suggest thatPHA-4 and DAF-12 endow the pharynx with transcriptional plasticity to respondto diverse developmental and physiological cues. Our combination of bioin-formatics and in vivo analysis has provided a powerful means for genome-wideinvestigation of transcriptional control.
A critical question in developmental biolo-gy is how complex programs of gene ex-pression are orchestrated by a class ofregulators known as selector genes. Selec-tor genes code for transcription factors thatautonomously govern the fates of groups ofcells related to each other by virtue of their
cell type, position, or affiliation to an organ(1). For example, the FoxA transcriptionfactor PHA-4 dictates the identity of cellswithin the Caenorhabditis elegans phar-ynx. Embryos that lack pha-4 fail to gen-erate pharyngeal cells, and converselyectopic pha-4 is sufficient to drive nonpha-ryngeal cells toward a pharyngeal fate (2,3). PHA-4 also functions during postem-bryonic development, because reduction ofpha-4 activity at birth is lethal (4). Thesedramatic phenotypes reflect the global reg-ulatory role of PHA-4 within pharyngealcells. Many, perhaps all, genes selectivelyexpressed within the pharynx are activateddirectly by PHA-4, including genes ex-pressed in different pharyngeal cell typesand at different developmental stages (4).
This strategy raises the question of how asingle transcription factor can mediate di-verse transcriptional outcomes within dif-ferent cellular contexts. Combinatorial reg-ulation by multiple transcription factors isone likely mechanism. However, few tran-scription factors have been discovered thatcould act in conjunction with PHA-4 (5, 6).Here, we explore the cis-regulatory logicfor expression within pharyngeal cells, witha particular focus on growth control inresponse to food availability.
Gene expression profiles for pharyn-geal cell types. To analyze expression pro-files within subsets of pharyngeal cells, wesubdivided 339 candidate pharyngeal genespreviously identified by microarray analy-sis (Fig. 1, fig. S1, and table S1) (4, 7). Wetook advantage of RNA in situ patterns (8),reporter expression, and placement on theC. elegans Topological Expression Map (9)(Topo Map) to generate five clusters ofgenes with shared expression profiles. Onthe Topo Map, genes are positioned accord-ing to their correlated expression across553 independent microarray experiments togenerate “mountains” that reflect expres-sion within a common cell type or cellularprocess. The clusters of pharyngeal genesencompassed 65% of the microarraypositives and defined genes expressed inpharyngeal muscles (Ph-M), pharyngealglands (Ph-G), pharyngeal marginal cells(Ph-MC), epithelia (Epi), and pharyngealmuscle and marginal cells combined(Ph-MMC) (fig. S1 and table S1). Wevalidated these assignments with greenfluorescent protein (GFP) reporters forpreviously uncharacterized members ofeach cluster (Fig. 1).
The compendium of pharyngeal geneclusters provided a tool to explore theregulatory circuitry for cell type–specific
1Huntsman Cancer Institute, University of Utah, 2000Circle of Hope, Salt Lake City, UT 84112, USA. 2Ge-nome Bioinformatics Group, University of California,Santa Cruz, CA 95064, USA.
*These authors contributed equally to this work.†Present address: Genes and Development ResearchGroup, University of Calgary, Calgary, Alberta AB T2N4N1, Canada.‡To whom correspondence should be addresssed. E-mail: [email protected]
G Ph-M
M03D4.4::GFP C15H9.9::GFP
J Ph-MCPh-MMC (14) Ph-MMC (29)Total Ph-M Epi
H Epi
F21D5.9::GFP
F Ph-G
C49G7.4::GFP
I Ph-MMC(14)
ZK1067.7::GFP
A B C D E
AdhesionUnknown OtherTrxn Factor ShTK Prot. Inh.
Protease Kin./Phos.GST
F boxEnzyme
ECM DUF139Cytosk./Musc.Chan./Recep.
Fig. 1. Five pharyngeal clusters. Piecharts of protein categories for allcandidate pharyngeal genes (A) andindividual clusters (B to E). GST, glu-tathione S-transferase; ECM, extra-cellular matrix protein; Prot. Inh.,protease inhibitor; ShTK, ShTK do-main–containing protein; Chan./Re-cep., channel molecule or receptor;Cytosk./Musc., cytoskeleton or mus-cle protein; Enzyme, metabolism en-zyme; DUF139, domain of unknownfunction 139 domain; Trnx Factor,transcription factor; and Kin./Phos.,kinase or phosphatase. (F to J) Pre-viously uncharacterized genes wereexpressed as predicted. C49G7.4 inPh-G, confirmed by co-staining witha gland-specific antibody, J126 (19),M03D4.4 in Ph-M, F21D5.9 in embryonic Epi, ZK1067.7 in late muscles and marginal cells from Topo Mounts 14 or 29 (Ph-MMC) (9), and C15H9.9in Ph-MC. Dotted lines indicate the pharynx [(F) to (J)].
RESEARCH ARTICLES
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1743
expression. We created the Improbizer al-gorithm (10) to identify potential cis-regulatory sites enriched in the pharyngealgene clusters (11). Improbizer searches formotifs in DNA or RNA sequences thatoccur with unexpected frequency by usinga variation of the expectation maximizationalgorithm (12). As a negative control, weexamined groups of genes (DNA synthesisor a set of 194 randomly selected genes)that were not specifically expressed in thepharynx and removed motifs common toboth the pharyngeal and negative controlsets. This analysis identified seven candi-date regulatory elements (Fig. 2, fig. S2,and tables S4 and S5). To test whetherthese elements were biologically active, weintroduced three copies of each motif up-stream of a minimal pes-10 promoter (13)and examined them for their ability toactivate expression.
Five of seven candidate motifs dis-played enhancer activity, indicating thatour bioinformatics approach efficientlyidentified cis-regulatory elements thatfunctioned in vivo. Four were active withinrestricted domains, whereas one, M-1, be-haved ubiquitously throughout the embryo(Fig. 2D). Motif M-2, identified from Ph-M, was the most specific and activatedexpression within pharyngeal muscles.GFP expression initiated during mid-embryogenesis (bean stage) (14), peakedduring pharyngeal morphogenesis (two- tothreefold stages), and decreased dramati-cally after hatching. Motif 29-4, identifiedfrom Ph-MMC, was active in anterior em-bryonic cells, including those of the phar-ynx. Reporters were expressed in the headand broadly throughout the pharynx begin-ning at mid-embryogenesis (1.5- to 2-foldstage). Robust expression was maintaineduntil hatching, after which only a few cellscontinued to express. Two regulatory mo-tifs, 12-1 and 12-5, were associated withthe Epi cluster and activated expression in
ectoderm (pharynx, neurons, and epider-mis). For example, reporters for 12-5expressed GFP in the pharynx (71%); phar-ynx and neurons (24%); or pharynx, neu-rons, and epidermis (5%). Both 12-1 and12-5 were active in bean-stage embryos.Reporters for 12-1 maintained GFP expres-sion to adulthood, whereas 12-5-dependentexpression peaked at the two- to threefoldstage and subsequently declined. These fivecis-regulatory elements suggest a simplecode for expression within pharyngeal ep-ithelia. We propose that PHA-4 sites con-tribute to organ-wide activation throughoutthe pharynx whereas additional elementsimpart positional (29-4) or cell-type (M-2,12-1, and 12-5) information.
The M-2 motif. We examined the activ-ity of the cis-regulatory elements withinnatural pharyngeal promoters to addresstheir importance for endogenous genes. Wefocused on the M-2 motif because it washighly selective for pharyngeal muscle. Toidentify relevant instances of the motif, wechose four genes that were expressed in pha-ryngeal muscles and carried a perfect match tothe M-2 consensus in C. elegans and the rela-ted species C. briggsae (15): the heavychain myosin genes F45G2.2 and myo-2 (16),the Nkx2.5 homeobox homolog ceh-22
(17, 18), and the predicted zinc finger M03D4.4.The M-2 motif was required in natural
promoters for robust expression. Whereasmost transgenic animals expressed GFPstrongly in pharyngeal muscles throughoutlife, expression was reduced dramatically atall stages when M-2 was mutated (Fig. 3Dand Table 1) (19). Fewer animals had GFP,and expression was weaker for those that did.The presence of additional regulatory ele-ments accounts for the residual expressionobserved for promoters bearing M-2 muta-tions (4, 17, 20).
A current challenge for computationalsearches for cis-regulatory sites is to iden-tify the trans-acting factors and upstreamregulatory pathways that impinge uponthese sites. Motifs 12-1 and 12-5 resembleknown binding sites for the novel factorsPEB-1 and CEB/P�, repectively (21, 22).We considered that T-box proteins mightrecognize the M-2 element (23); however,no effect on M-2-dependent expressionwas observed when eight predicted T-boxgenes were inactivated (table S6). We useda yeast one-hybrid screen (24) and obtaineda single candidate, isolated 12 times, thatrecognized six copies of an intact M-2motif but not a mutated version (Fig. 3B).This candidate was daf-12, which encodes
Fig. 2. Predicted cis-regulatory motifs func-tion in vivo. (A) Dia-gram of pharyngeal nu-clei (green, myoepithe-lia; red, neurons; gray,pharyngeal epitheliacells; orange, gland cells;and black, marginalcells). (B) Head of anadult worm featuringthe bilobed pharynx(dotted). (C and D) Fiveof seven motifs dis-played enhancer activi-ty in embryos whenplaced upstream of aminimal pes-10 report-er (C) (4), which alonehad no activity (7).
Table 1. Pharyngeal muscle gene expression is reduced when M-2 or daf-12 is mutated under growthconditions. GFP expression was determined in independent transgenic lines (n), with �20 animalsexamined per line. “mut” indicates mutant M-2 sites. Inactivation of M-2, daf-12, or both lead to anequivalent reduction in GFP expression.
Reporter StrainStrong
(n)Reduced
(n)Dramaticallyreduced (n)
None(n)
myo-2P::GFP Wild type 4 2 3 1myo-2(mut)P::GFP Wild type 1 4 8 4myo-2P::GFP daf-12 (m20) 0 1 3 2myo-2(mut)P::GFP daf-12 (m20) 0 0 3 3ceh-22P::GFP Wild type 2 6 1 2ceh-22(mut)P::GFP Wild type 1 1 6 4ceh-22P::GFP daf-12 (m20) 0 4 8 2ceh-22(mut)P::GFP daf-12 (m20) 0 2 8 2
R E S E A R C H A R T I C L E S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1744
a nuclear hormone receptor similar to thepregnane X and vitamin D receptors (25,26). Electrophoretic mobility shift assayswith the ceh-22 promoter revealed thatDAF-12 bound M-2-containing sequencesin vitro and that binding was specific(Fig. 3C). These findings demonstratethat the M-2 element is recognized byDAF-12 in vitro.
To ascertain the importance of DAF-12for M-2 activity in vivo, we examinedmyo-2P::GFP and ceh-22P::GFP in daf-12(m20) loss-of-function mutants (27).Mutant animals expressed GFP at a reducedlevel: Both the number of cells and GFPintensity were lower, similar to the effectsof M-2 mutations (Fig. 3D and Table 1).Animals carrying double mutations in daf-12 and M-2 resembled those with eithersingle mutation, as expected if DAF-12
binds M-2 (Fig. 3E and Table 1). Weconclude that DAF-12 is required for myo-2and ceh-22 expression and functionsthrough the M-2 element.M-2 and modulation of expression by
food availability. DAF-12 is a critical reg-ulator of developmental progression and re-sponse to environmental cues (28, 29). Whenconditions are harsh, nematode larvae enter along-lived state of diapause called the dauerstage. Dauer larvae exhibit multiple adapta-tions to stress, including remodeling of thepharynx to become thinner radially and ces-sation of feeding. The choice between growthand dauer development depends on insulin,transforming growth factor–�, and heterotri-meric guanine nucleotide–binding protein–coupled receptor signaling pathways, whichconverge on a handful of transcription fac-tors, including DAF-12 (25, 26, 30). A key
question is how DAF-12 executes its biolog-ical functions to mediate these developmentalevents.
Given the role of DAF-12, we testedwhether the M-2 motif modulates expressionin dauer larvae. Wild-type myo-2P::GFP andceh-22P::GFP were each expressed stronglyin pharyngeal cells and down-regulated indauer animals (Fig. 3D and Table 1) (31).Once food was restored, GFP gradually re-turned to its previous robust level as animalsexited the dauer program (Table 2). By con-trast, animals bearing a mutated M-2 motiffailed to decrease expression in dauer larvaeor reactivate expression upon feeding (Fig.3D and Table 2). These effects were specificbecause transcriptional or translationalPHA-4::GFP constructs, which lack an M-2element, were not modulated in dauer larvae(19). We conclude that regulation of myo-2and ceh-22 during dauer development de-pends critically on the M-2 motif.
Reduced myo-2 and ceh-22 expressionin dauer larvae could reflect repression byDAF-12 or loss of activation. To distin-guish between these possibilities, we exam-ined CEH-22::GFP in daf-2(insulin recep-tor); daf-12 double mutants, which formdauer larvae despite reduced daf-12 (30).We reasoned that GFP expression woulddecrease normally in daf-12 dauer larvae ifdown-regulation reflected loss of activationbut would increase relative to the wild typeif down-regulation required DAF-12 re-pression. We found that CEH-22::GFP wasderepressed in daf-2; daf-12 double mu-tants and pharyngeal morphology resem-
C
A
M-2 + daf-12
M-2
M-2 (mut) + daf-12
M-2 +negative
B
myo-2- 5500 D Growth Dauer
myo-2P::GFP myo-2P::GFP
myo-2P(mut)::GFP myo-2P(mut)::GFP
ceh-22P::GFP ceh-22P::GFP
ceh-22P(mut)::GFP ceh-22P(mut)::GFP
daf-12;myo-2P::GFP
daf-12;ceh-22P::GFP
daf-12;myo-2P(mut)::GFP
daf-12;ceh-22P(mut)::GFP
ceh-22
E
WT MutF M P
- 1600 0
Fig. 3. The M-2 motif binds DAF-12 and mediates the transcrip-tional response to food. (A) The ceh-22 and myo-2 promoterswith conserved sites for M-2 (red), CEH-22/Nkx2.5 (green), andPHA-4/FoxA (blue). (B) Association between DAF-12 and threecopies of wild-type but not mutant M-2 in yeast, grown onselective medium as described in (11). (C) DAF-12 binds M-2sequences from the ceh-22 promoter in vitro. F, free DNA; M,DNA plus reticulocyte lysate; and P, DNA plus DAF-12 DNAbinding domain. Competition using unlabeled wild-type (WT )and mutant (Mut) competitor DNA at 50�, 200�, and 1000�molar excess reveals two specific shifted products. (D) Expressionwith WT or mutated M-2 elements under growth or dauer-inducing conditions. GFP expression was reduced under growthconditions when M-2 was mutated but failed to decrease furtherunder starvation conditions. (E) WT and mutated M-2 elementswere expressed equivalently under growth conditions in daf-12(m20) loss-of-function mutants.
Table 2. M-2 is required for recovery of pharyngeal muscle gene expression during dauer exit. Entry andexit into the dauer stage were induced by removal or readdition of food, respectively. GFP expression wasscored at 0, 3, or 8 hours after food restoration. Entries indicate the number of worms examined.
Reporter 0 hours recovery 3 hours 8 hours
myo-2P::GFP weak:16 weak:16 weak: 2strong: 4 strong: 4 strong:18
myo-2(mut)P::GFP weak:20 weak:20 weak:20strong: 0 strong: 0 strong: 0
ceh-22P::GFP weak:14 weak:14 weak: 4strong: 6 strong: 6 strong:16
ceh-22(mut)P::GFP weak:20 weak:20 weak:20strong: 0 strong: 0 strong: 0
R E S E A R C H A R T I C L E S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1745
bled that of growth conditions (Fig. 4).These data suggest that DAF-12 functions asa repressor in dauer larvae and that repressionis essential for pharyngeal remodeling.
We identified pharyngeal genes with oneor more predicted M-2 motifs and surveyedthose genes for regulation during dauer de-velopment. A total of 94 pharyngeal genescarried a conserved M-2 element, of which 26were down-regulated in dauer animals (28%)(31) (table S7). Conversely, 191 genes lackeda conserved M-2 element, of which 25 weremodulated in dauers (13%). The enrichmentof the M-2 element in dauer-regulated genessupports a role for this motif in response toenvironmental conditions. The majority ofdauer-regulated genes were associated withpharyngeal muscle clusters (22 of 26, or85%) (table S7) and included genes importantfor feeding, growth, and metabolism. For ex-ample, inx-6 is required for electrical cou-pling between pharyngeal muscles duringfeeding (32), nrs-2 and cyp-17 are predictedto contribute to protein synthesis or folding,and ech-4 is likely involved in fatty acid me-tabolism (33). These target genes, in additionto ceh-22, F45G2.2, and myo-2, are attractivecandidates to modulate feeding and growth ofthe pharynx in response to nutritional cues.
Exit from the dauer program, but not en-try, was critically dependent on PHA-4/FoxA. Dauer animals were induced by plac-ing daf-2(ts) larvae at a nonpermissive tem-perature. Animals with pha-4 amountsreduced by RNA interference (RNAi) [pha-4(RNAi)] could form dauer larvae as effi-ciently as pha-4(�) animals (Fig. 4). Further-more, destruction of two predicted Fox bind-ing sites within the myo-2 promoter did notdisrupt dauer-dependent repression ofmyo-2P::GFP (fig. S4). We conclude thatpha-4 is not required for the dauer program of
development. However, pha-4 was essentialfor exit from the dauer program and hyper-trophy of the pharynx under growth condi-tions. When daf-2(ts) dauer animals wereshifted to permissive temperature for 32hours, only 13% of pha-4(RNAi) larvae re-covered and resumed growth (n � 32), com-pared to 92% of pha-4(�) animals (n � 37).The pha-4(RNAi) larvae remained small withpartially remodeled pharynges and undevel-oped gonads (Fig. 4). pha-4(RNAi) dauer lar-vae were viable for extended periods andresumed growth when pha-4 activity was re-stored with food (19). Thus, the failure ofpha-4(RNAi) larvae to reinitiate growth didnot reflect a general unhealthiness of theseanimals. We conclude that the developmentalselector gene pha-4 is redeployed postembry-onically to promote larval growth, pharyn-geal hypertrophy, and sexual maturation inresponse to food.
We computationally identified five cis-regu-latory sequences and tested their function invivo. One of these elements mediates the re-sponse to environmental cues and is recognizedby DAF-12. We speculate that when conditionsare favorable, DAF-12, bound to an unidentifiedligand, and PHA-4 function as transcriptionalactivators for genes involved in feeding, hyper-trophy, and metabolism. When conditions areharsh, loss of the DAF-12 ligand converts DAF-12 into a transcriptional repressor and therebytriggers dauer development, pharyngeal remod-eling, and cessation of feeding. This model pro-vides an explanation for why loss of daf-12activity blocks entry into dauer developmentwhereas mutations predicted to interfere withproduction of a DAF-12 ligand lead to constitu-tive dauer formation (34–37). These studies re-veal how the transcriptional program can re-spond to nutrition to coordinate organ growthand activity.
References and Notes1. R. S. Mann, S. B. Carroll, Curr. Opin. Genet. Dev. 12,
592 (2002).2. S. E. Mango, E. J. Lambie, J. Kimble, Development 120,
3019 (1994).3. M. A. Horner et al., Genes Dev. 12, 1947 (1998).4. J. Gaudet, S. E. Mango, Science 295, 821 (2002).5. P. G. Okkema, A. Fire, Development 120, 2175 (1994).6. J. D. Thatcher, A. P. Fernandez, L. Beaster-Jones, C.
Haun, P. G. Okkema, Dev. Biol. 229, 480 (2001).7. J. Gaudet, S. Muttumu, M. Horner, S. E. Mango, PLoS
Biol., in press.8. More information is available at http://nematode.
lab.nig.ac.jp/db/index.html.9. S. K. Kim et al., Science 293, 2087 (2001).
10. The Improbizer algorithm is available online at www.cse.ucsc.edu/�kent/improbizer/improbizer.html.
11. Materials and methods are available as supportingmaterial on Science Online.
12. T. L. Bailey, C. Elkan, Proc. Int. Conf. Intell. Syst. Mol.Biol. 2, 28 (1994).
13. A. Fire et al., in GFP Strategies and Applications,M. Chalfie,S. Kain, Eds. (Wiley, New York, 1998), pp. 153–168.
14. J. E. Sulston, E. Schierenberg, J. G. White, J. N. Thom-son, Dev. Biol. 100, 64 (1983).
15. L. D. Stein et al., PLoS Biol. 1, E45 (2003).16. D. M. Miller, F. E. Stockdale, J. Karn, Proc. Natl. Acad.
Sci. U.S.A. 83, 2305 (1986).17. P. G. Okkema, E. Ha, C. Haun, W. Chen, A. Fire,
Development 124, 3965 (1997).18. T. Vilimas, A. Abraham, P. G. Okkema, Dev. Biol. 266,
388 (2004).19. W. Ao, J. Gaudet,W. J. Kent, S. Muttumu, S. E. Mango,
unpublished data.20. J. D. Thatcher, C. Haun, P. G. Okkema, Development
126, 97 (1999).21. L. Beaster-Jones, P. G. Okkema, J. Mol. Biol. 339, 695
(2004).22. More information is available at www.gene-regula-
tion.com.23. A. Kispert, B. G. Herrmann, EMBO J. 12, 3211 (1993).24. M. M. Wang, R. R. Reed, Nature 364, 121 (1993).25. A. Antebi, W. H. Yeh, D. Tait, E. M. Hedgecock, D. L.
Riddle, Genes Dev. 14, 1512 (2000).26. M. I. Snow, P. L. Larsen, Biochim. Biophys. Acta 1494,
104 (2000).27. D. L. Riddle, M. M. Swanson, P. S. Albert, Nature 290,
668 (1981).28. M. Tatar, A. Bartke, A. Antebi, Science 299, 1346 (2003).29. C. E. Finch, G. Ruvkun, Annu. Rev. Genomics Hum.
Genet. 2, 435 (2001).30. P. L. Larsen, P. S. Albert, D. L. Riddle, Genetics 139,
1567 (1995).31. J. Wang, S. K. Kim, Development 130, 1621 (2003).32. S. Li, J. A. Dent, R. Roy, Mol. Biol. Cell 14, 2630 (2003).33. More information is available at www.wormbase.org.34. P. S. Albert, D. L. Riddle, Dev. Biol. 126, 270 (1988).35. B. Gerisch, C. Weitzel, C. Kober-Eisermann, V. Rot-
tiers, A. Antebi, Dev. Cell 1, 841 (2001).36. K. Jia, P. S. Albert, D. L. Riddle, Development 129, 221
(2002).37. A. Antebi, J. G. Culotti, E.M. Hedgecock, Development
125, 1191 (1998).38. We thank A. Fire, Y. Kohara, and J. Kiefer for plasmids;
R. Barstead for cDNA libraries; K. Yamamoto, H. Mak,and G. Ruvkun for communicating results beforepublication; and S. Dames for technical assistance.Some nematode strains were provided by the C.elegans Genetics Center, funded by NIH NationalCenter for Research Resources. This work was sup-ported by NIH R01-GM56264 to S.E.M. and CanadianInstitutes of Health Research funding to J.G. S.E.M. isan associate investigator of the Huntsman CancerInstitute. Molecular interaction data have been de-posited in the Biomolecular Interaction Network Da-tabase with the accession code 151736. DNA se-quencing was supported by the NIH (2P303A42014).
Supporting Online Materialwww.sciencemag.org/cgi/content/full/305/5691/1743/DC1Materials and MethodsFigs. S1 to S4Tables S1 to S8References
1 July 2004; accepted 4 August 2004
B
Ddaf-2; ceh-22 P::GFP
daf-2;daf-12;ceh-22P::GFP
A
Cdaf-2; ceh-22 P::GFP
daf-2;daf-12;ceh-22 P::GFP
daf-2; pha-4, recovery
H
daf-2; pha-4, dauer
G
F
daf-2, recovery
Dauer Growth
daf-2, dauer
E
Fig. 4. (A to D) DAF-12is required to represspharyngeal muscle ex-pression in dauer lar-vae. Reduction ofceh-22P::GFP in dauerlarvae [(A) and (B)] waslost in daf-12 mutants[(C) and (D)]. (E to H)PHA-4 is required fordauer exit but not en-try. daf-2(ts); pha-4(RNAi) animals wereshifted to a nonpermis-sive temperature to in-duce dauer entry andpharyngeal remodeling[(E) and (G)]. Whentransferred to permis-sive temperature, daf-2(ts); pha-4(RNAi) ani-mals failed to exit thedauer stage and resumegrowth [(F) and (H)].
R E S E A R C H A R T I C L E S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1746
Mitochondrial FusionIntermediates Revealed in Vitro
Shelly Meeusen,1 J. Michael McCaffery,2 Jodi Nunnari1*
The events that occur during the fusion of double-membraned mitochondria areunknown. As an essential step toward determining the mechanism of mito-chondrial fusion, we have captured this event in vitro. Mitochondrial outer andinner membrane fusion events were separable and mechanistically distinct, butboth required guanosine 5-triphosphate hydrolysis. Homotypic trans interac-tions of the ancient outer transmembrane guanosine triphosphatase, Fzo1, wererequired to promote the fusion of mitochondrial outer membranes, whereaselectrical potential was also required for fusion of inner membranes. Ourconclusions provide fundamental insights into the molecular events drivingmitochondrial fusion and advance our understanding of the evolution of mi-tochondrial fusion in eukaryotic cells.
In eukaryotic cells, homotypic mitochondrialfusion events occur continuously throughoutthe cell cycle. These fusion events are bal-anced by mitochondrial fission events, andtogether they function to create a distribut-able and responsive mitochondrial compart-ment (1). As a result of their endosymbioticorigin, mitochondria possess two structurallyand functionally distinct membranes. Duringmitochondrial fusion, two pairs of thesemembranes are coordinately and accuratelyfused. The mechanism by which these fourmembranes rapidly fuse into two continuous,yet distinct, bilayers is not understood. Mito-chondrial membranes have not been observedto undergo fusion with other endomem-branes, and conserved core secretory fusioncomponents, such as soluble N-ethylmaleim-ide–sensitive factor attachment protein recep-tors, are not required for homotypic mito-chondrial fusion. These features suggest thatmitochondrial fusion evolved independentlyfrom secretory fusion and that the fundamen-tal steps in membrane fusion are mediated ina mechanistically unique manner.
Three proteins in yeast—Ugo1, Mgm1,and Fzo1—are required for mitochondrialfusion in vivo based on cytological assaysfor mitochondrial morphology and mito-chondrial content mixing during yeast mat-ing. Ugo1 is an outer membrane protein,with several predicted transmembrane re-gions, and is a member of the mitochondri-al transport family (2, 3). Fzo1 and Mgm1are highly conserved large guanosinetriphosphatases (GTPases) and are compo-nents of the mitochondrial outer and inner
membranes, respectively (4–6). Mgm1 is adynamin-related GTPase protein (DRP)and is tethered to the inner membrane andlocalized to the intermembrane space (6).Genetic analysis indicates that Mgm1 inter-acts with itself and that its GTPase domainis required for fusion, suggesting that itfunctions in mitochondrial fusion in a sim-ilar way to other DRPs, as a self-assem-bling GTPase (7, 8). The Fzo1 GTPase isan integral membrane protein that spans theouter membrane twice; it has a small loopof functionally important amino acids inthe intermembrane space, and its N-termi-nal GTPase domain and C terminus are inthe cytosol (9). The GTPase domain ofFzo1 is most similar to a family of eubac-terial GTPases, suggesting that it is derivedfrom the mitochondrial ancestral pro-karyote (10). Among eukaryotic GTPases,however, the Fzo1 GTPase domain is mostclosely related to the DRP family GTPasedomain (11). Members of the Fzo1 GTPasefamily also possess, like DRPs, regionspredicted to form coiled-coil structures,raising the possibility that they are modi-fied but bone fide members of the DRPfamily and function in mitochondrial fusionthrough self-interaction and assembly.
Conserved components that mediate mi-tochondrial fusion and mitochondrial fis-sion play an important role in the transmis-sion of the cell death response in mamma-lian cells (12–14). Mutations in two con-served human fusion proteins, Opa1, theMgm1 ortholog, and Mfn2, an Fzo1 or-tholog, result in two types of neurodegen-erative diseases: dominant optic atrophyand Charcot-Marie-Tooth neuropathy, re-spectively, consistent with a role of theseproteins in cell death (15–17).
Mgm1, Fzo1, and Ugo1 have been shownto interact physically (7, 8, 18), suggestingthat outer and inner membranes share a com-mon fusion apparatus, but the exact role of
these components and their interactions infusion are unknown. Indeed, discrete steps inmitochondrial fusion have not been de-scribed, primarily because this event hasproven difficult to replicate in vitro.Mitochondrial fusion in vitro. To un-
derstand the molecular events required for mi-tochondrial fusion, we developed an in vitrocytological assay that measures fusion of outerand inner mitochondrial membranes (19).Equivalent amounts of mitochondria containingeither matrix-targeted green fluorescent protein(m-GFP) or matrix-targeted Discosoma red flu-orescent protein (m-dsRed) were mixed togeth-er, concentrated by centrifugation, and resus-pended in the presence of cytosolic extract,adenosine 5-triphosphate (ATP), guanosine 5-triphosphate (GTP), and an energy regenerationsystem. Fusion of both the outer and innermembranes was assessed by matrix contentmixing, reflected by the colocalization of m-GFP and m-dsRed into single individually re-solvable mitochondrial structures in three di-mensions (Fig. 1, A and B, and movie S1).Fusion was quantified by determining the num-ber of mitochondria containing both m-GFPand m-dsRed and dividing by the total numberof mitochondria analyzed (n � 200). In vitromitochondrial fusion occurred in a time- andtemperature-dependent manner, consistently at-taining 10 to 15% by 30 min at 22°C (Fig. 1, Band C, and fig. S1A). Because we could onlydetect m-GFP and m-dsRed content-mixingevents, the efficiency of mitochondrial fusion inour assay was substantially higher than 10 to15%. We also observed successive fusionevents at time points greater than 30 min, whichindicates that our content-mixing assay was anunderestimate of total fusion efficiency. Mito-chondrial fusion was highly dependent on ex-ogenous nucleotide triphosphates (NTPs) andan energy regeneration system (Fig. 2) but notdependent on the addition of cytosolic extract,indicating that non–mitochondrial-associatedproteins were not required for fusion (fig. S1B).
Three criteria indicate that our matrixcontent-mixing assay was an accurate re-flection of mitochondrial fusion. First, mi-tochondria containing both m-GFP and m-dsRed were larger in diameter along theirlong axis than mitochondria containingonly GFP or dsRed (Fig. 1D; gray barsrepresent unfused mitochondria, black barsrepresent fused mitochondria). Consistent-ly, under conditions where fusion was ob-served, a population of larger single-la-beled m-GFP and m-dsRed also appeared(fig. S2, A and B). Second, the relativefluorescence intensity of GFP and dsRed infused mitochondria was decreased as com-pared with that of single-labeled mitochon-dria, indicating that fluorophores were di-luted as a result of an increase in mitochon-drial volume from fusion (Fig. 1B; averagepixel intensity of fused mitochondria was
1Section of Molecular and Cellular Biology, Center ofGenetics and Development, University of California,Davis, CA 95616, USA. 2Department of Biology andIntegrated Imaging Center, Johns Hopkins University,Baltimore, MD 21218, USA.
*To whom correspondence should be addressed.E-mail: [email protected]
R E S E A R C H A R T I C L E S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1747
520, average pixel intensity of unfused mi-tochondria was 1252; a Student’s t testresulted in P � 0.000056). Third, immuno-electron microscopy analysis demonstrateda colocalization of gold-conjugated anti-bodies directed against GFP and dsRED infixed mitochondria obtained from a fusionreaction (Fig. 1F). In contrast, in fixedmitochondria obtained from a control reac-tion in which no fusion was observed, gold-conjugated antibodies directed against GFPand dsRed were observed only in separatemitochondria (Fig. 1E).
Monitoring the behavior of mitochondrialabeled with m-GFP and m-dsRed by time-lapse fluorescent microscopy also confirmedthat mitochondrial fusion occurred in vitro(movie S2, A and B). Specifically, adjacentmitochondria labeled with m-GFP andm-dsRed were observed to extend toward eachother and mix matrix contents. Within our timeresolution, membrane extension and matrixcontent mixing were rapid and unresolvedevents, similar to in vivo observations in whichmitochondrial tubules fuse upon contact (1).Thus, the cytological content-mixing assay rep-resents a reliable measure of mitochondrial fu-sion in vitro.
The energetics of mitochondrial fu-sion. Two mitochondrial membrane pro-teins, Fzo1 and Mgm1, required for mito-chondrial fusion in vivo, are predicted to beGTPases, and mutations in the GTPase do-
mains of both proteins result in mitochondrialfusion defects in vivo (4, 7, 8). However, adirect role for GTP hydrolysis in mitochon-drial fusion has not been demonstrated.
We examined the nucleotide requirementsand the effects of nonhydrolyzable nucleotideanalogs on content mixing in vitro (Fig. 2).Mitochondrial fusion was completely depen-dent on NTPs. The energy regeneration sys-tem alone supported a small amount of fu-sion, indicating that isolated mitochondriacontain an endogenous pool of NTPs. Treat-ment of mitochondria with apyrase, addedbefore the assay to deplete NTPs, completelyabolished fusion in a reaction containing anenergy regeneration system (20). The addi-tion of exogenous ATP to a reaction contain-ing the energy regeneration system did not
further stimulate fusion, indicating either thatmitochondria possess sufficient endogenousATP to support fusion or that ATP was notrequired for mitochondrial fusion. In contrast,the addition of exogenous GTP in the pres-ence of the energy regeneration system sub-stantially stimulated the efficiency of mito-chondrial fusion, suggesting that the amountof GTP in mitochondria was limiting andrequired for mitochondrial fusion.
To test whether mitochondrial fusion in vitrorequired GTP hydrolysis, we added excess non-hydrolyzable GTP analogs to a reaction contain-ing an energy regeneration system and ATP. Inthe presence of guanosine 5-O-(3-thiotriphos-phate) (GTP-�-S) or guanosine 5-monophos-phate guanosine 5 [�,�-imido]triphosphate(GMPPNP), fusion was substantially reduced,
Fig. 1. Mitochondrial fusion in vitro. (A) Schematic of in vitro fusionassay. (B) Fluorescent images of a fusion reaction with m-GFP andm-dsRed mitochondria. Arrows indicate fused mitochondria. Scalebar, 2 m. (C) Fixed time-point analysis of in vitro mitochondrialfusion. (D) Comparison of mitochondrial diameter along long axis ofunfused (gray) and fused (black) mitochondria labeled with m-GFP
and m-dsRed. Total number of mitochondria analyzed in each casewas 56. (E and F) Immunoelectron microscopy analysis of m-GFP andm-dsRed localization in mitochondria from 0-min (E) and 20-min (F)fusion reactions. Large gold particles (red arrowheads) indicate im-munolabeled dsRed and small gold particles (black arrowheads) indi-cate immunolabeled GFP.
Fig. 2. Mitochondrial fusion in vitro requiresGTP hydrolysis and inner mitochondrialmembrane potential. In vitro fusion reactionswere conducted as described and fusion effi-ciency is expressed as a percentage of thestandard reaction, which contains an energyregeneration system (ERS), 1 mM ATP, and0.5 mM GTP (19). Stage 1 mitochondria wereresuspended and placed under stage 2 condi-tions in the presence of nonhydrolyzableNTPanalogs and treatments as described (19).Error bars show mean � SD. VAL, valinomy-cin; NIG, nigericin.
R E S E A R C H A R T I C L E S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1748
indicating that GTP hydrolysis was essential.The addition of excess guanosine 5-O-(2-thio-diphosphate) (GDP-�-S) also inhibited fusion,providing further evidence that GTP binding andhydrolysis were essential. In contrast, the addi-tion of an excess amount of nonhydrolyzableATP [adenosine 5-O-(3-thiotriphosphate)] didnot reduce fusion, indicating that in vitro ATPhydrolysis was not required. Thus, GTP but notATP hydrolysis was required for fusion, consis-tent with essential roles of the two large GTPasesFzo1 and Mgm1 in mitochondrial fusion in vivo.
During the development of the in vitro as-say, we observed that mitochondrial fusion wasstrongly influenced by yeast cell culture media,particularly the carbon source (fig. S1D). Spe-cifically, mitochondria isolated from cellsgrown on nonfermentable carbon sources effi-ciently fused in vitro, whereas those isolatedfrom cells grown on a fermentable carbonsource were unable to fuse in vitro. This led usto test directly whether mitochondrial mem-brane potential played a role in mitochondrial
fusion by determining the effects of the electrontransport chain uncoupler, carbonylcyanide m-chlorophenylhydrazone (CCCP) (Fig. 2). WhenCCCP was present during the assay, fusion wasabolished. CCCP also inhibits mitochondrialfusion in mammalian cells, indicating thatmembrane potential is a conserved require-ment (21).
To dissect the requirement for mitochondri-al inner membrane potential, we examined theeffects of two additional ionophores on fusion:valinomycin, an electrogenic K� ionophore,which specifically dissipates the electrical gra-dient, and nigericin, an electroneutral K�/H�
ionophore, which specifically dissipates theproton gradient (Fig. 2). Mitochondrial contentmixing was highly sensitive to valinomycin, butsignificantly less sensitive to nigericin, indicat-ing that the electrical and not the protongradient was required for efficient mitochondri-al fusion.Mitochondrial fusion proceeds through
discrete and sequential mitochondrial
outer and inner membrane fusion events.The in vitro fusion reaction was divided into twoexperimental stages: Stage 1 included mitochon-drial centrifugation, incubation, and resuspen-sion, and stage 2 included the addition of exog-enous NTPs and an energy regeneration system(19). To assess quantitatively the requirement ofstage 1 for fusion efficiency, either mitochondriawere centrifuged, incubated, and resuspended inthe presence of the energy regeneration systemand NTPs, or they were immediately resuspend-ed with the energy regeneration system andNTPs. Content-mixing efficiency in each reac-tion was determined after 60 min of incubation at22°C. In the absence of stage 1 treatment, mito-chondrial fusion was markedly reduced (Fig.3A). Both the centrifugation and incubationsteps of stage 1 were essential for efficient fusionduring stage 2 (fig. S1C). Thus, bringing mito-chondrial membranes into close proximity for acritical duration was a required and rate-limitingstep. In vivo, this step is likely to be mediated bycytoskeletal elements, such as actin, which inyeast function both to tether and to move mito-chondria (22).
We then assessed whether mitochondrialconcentration was a critical parameter for stage2 of the reaction (Fig. 3B). After 10 min at stage2, mitochondria were diluted 20-fold, but theconcentrations of the energy regeneration sys-tem and NTPs were maintained. The dilutedreaction was incubated for an additional 50 minfor a total of 60 min. The fusion efficiency ofthe diluted reaction was reduced, comparedwith the undiluted 60-min control reaction, in-dicating that mitochondrial concentration wasimportant, but not essential, during stage 2. Inaddition, the fusion efficiency of the dilutedreaction at 60 min was greater than that of theundiluted control reaction assessed at 10 min,the time of dilution, indicating the existence ofdilution-resistant intermediates capable of com-pleting fusion. Thus, during stage 1, intermedi-ate fusion structures formed and went on to fusein an energy-dependent manner during stage 2.
We examined stage 1 mitochondria with theuse of fluorescence microscopy to look for in-termediate structures. Two classes of morpho-logical structures were observed: clustered struc-tures with a region lacking a fluorescence signalbetween adjacent mitochondria (Fig. 3CII) andtightly juxtaposed deformed structures with noregion lacking a fluorescence signal betweenthem (Fig. 3CII, arrows). In contrast, mitochon-dria that bypassed stage 1 and were placed di-rectly under stage 2 conditions for 60 min at22°C formed a significantly reduced number ofboth types of structures (Fig. 3CI). Thus, theclustered and deformed structures appear to rep-resent the dilution-resistant fusion intermediatesdetected during stage 2 of the reaction (Fig. 3B).A comparison of stage 1 mitochondria with stage2 mitochondria showed significantly fewer de-formed stage 2 mitochondria and a proportion-ally greater number of fused mitochondria, indi-
Fig. 3. Analysis of mitochondrial fusion in vitroreveals discrete intermediates. (A) The role of mi-tochondrial concentration in fusion. Comparison offusion efficiency in fusion reactions that either un-derwent or bypassed stage 1 concentration andincubation (19). (B) The effects of dilution on mito-chondrial fusion during stage 2. Comparison of thefusion efficiency in reactions that were either fixedat 10 min, or diluted 20-fold into reaction mix at 10min and incubated for an additional 50 min, orallowed to proceed under standard conditions to 60min (19). Error bars in (A) and (B) show mean � SD.(C) Representative fluorescent images of mitochon-drial structures labeled with m-GFP and m-dsRedthat formed in reactions that either bypassed (I andinsets), or underwent stage 1 conditions (II and insets). Scale bar, 8 m. Quantification of deformedor clustered structures in the total mitochondrial population is listed beneath respective conditions.(D) Quantification of deformed mitochondria (gray) and fused mitochondria (black) plotted as apercentage of total mitochondria after stage 1 and after stage 2 (n� 250 per condition). Error barsshow mean � SD (gray) and mean � SD (black).
R E S E A R C H A R T I C L E S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1749
cating that these structures were productive in-termediates in the fusion pathway (Fig. 3D; graybars represent deformed mitochondria, blackbars represent fused mitochondria). There wasless of a difference in the number of clusteredstage 1 versus stage 2 mitochondria, suggestingthat deformed structures represent a more ad-vanced fusion intermediate.
To determine the behavior of outer and in-ner mitochondrial membranes in these fusionintermediates, we examined stage 1 mitochon-dria by electron microscopy (EM). EM analysisalso revealed at least two classes of mitochon-drial structures (Fig. 4A): tightly associated mi-tochondria without obvious deformation (Fig.4A, black arrows) and tightly associated andreciprocally deformed mitochondrial pairs (Fig.4A, red arrows, and Table 1). Higher magnifi-cation of deformed mitochondria revealed thatthey possessed a continuous outer membraneencapsulating a boundary of two separate but
tightly aligned and associated inner mem-branes, suggesting that they were a product ofouter membrane fusion in the absence of innermembrane fusion (Fig. 4B, arrows). Thesestructures probably represent the deformedstructures observed by fluorescence microsco-py (Fig. 4AII). EM analysis revealed that agreater number of deformed structures was ob-served in stage 1 reactions compared with thatof either freshly isolated or stage 2 mitochon-dria (Table 1 shows stage 1; 27% of stage 1found in freshly isolated mitochondria, n �500, and 28% of stage 1 found in stage 2mitochondria, n � 200). We also observed byEM a population of tightly associated nonde-formed mitochondrial pairs (Fig. 4A, black ar-rows). In most cases, we were unable to visu-alize all four mitochondrial membranes withinthese pairs and thus were unable to determinewhether outer membrane fusion had occurred.However, it is likely that these tightly associat-
ed pairs of mitochondria represented the clus-tered structures visualized by fluorescence mi-croscopy (Fig. 4AI).
To substantiate our EM observations, wedeveloped a fluorescence microscopy–basedassay for outer membrane fusion (Fig. 5A)(19). Mitochondria labeled with m-dsREDand an outer membrane–targeted GFP (om-GFP) were mixed under various reaction con-ditions with an equivalent amount of mito-chondria labeled with matrix-targeted bluefluorescent protein (m-BFP). If outer mem-brane fusion occurred in the absence of innermembrane fusion, an outer membrane labeledwith om-GFP would be observed surroundingdoubly labeled but nonoverlapping matrixcompartments labeled with dsRED and BFP(Fig. 5A). Consistent with our EM observa-tions, analysis of stage 1 mitochondria withthe use of this assay revealed a significantpopulation of such structures (Fig. 5B, movieS3, and Table 1). In stage 2 reactions, thenumber of structures in which only the outermembrane had fused was significantly lessthan the number in stage 1 reactions, confirm-ing that these are intermediates in the fusionpathway (Table 1 shows stage 1; 62% ofstage 1 found in stage 2 reactions, n � 300).Consistent with our previous observations,outer membranes labeled with om-GFP sur-rounding colocalized m-dsRed and m-BFPspecifically appeared during stage 2, indicat-ing that inner membrane fusion had occurredunder these conditions (Fig. 5C).
Using this fluorescence-based assay, weasked whether outer membrane fusion also re-quired GTP and/or inner membrane potential(Fig. 5D). Pretreatment of mitochondria withapyrase severely inhibited outer membrane fu-sion of mitochondria during stage 1 (20). Simi-larly, the addition of GTP-�-S, GMPPNP, orGDP-�-S during stage 1 significantly reducedthe efficiency of outer membrane fusion, indi-cating that endogenous GTP was required topromote the fusion of the outer membrane.When CCCP was present during stage 1, outer
Fig. 4. Fusion of the outer mitochondri-al membrane and inner mitochondrialmembrane are separable events. (A) EManalysis of stage 1 mitochondria. Clus-tered and deformed mitochondria areindicated by black arrows and red ar-rowheads, respectively. Magnified fluo-rescent images of stage 1 mitochondriafrom Fig. 3C are shown representingclustered (I) and deformed (II) mito-chondrial structures. (B) EM images ofrepresentative deformed mitochondrialpairs. Arrowheads indicate regions ofcontinuous outer membrane encapsu-lating two separate, but tightly alignedand opposing inner membranes.
Fig. 5. Mitochondrialouter membrane fusionin vitro. (A) Schematicof in vitro outer mem-brane fusion assay. (Band C) Fluorescent im-ages of products fromfusion reactions withom-GFP/m-dsRed andm-BFP mitochondria af-ter (B) stage 1 (two ex-amples are shown) and(C) stage 2. White ar-rows in (B) indicate re-gions of continuousouter membrane con-necting two distinctmatrix compartments.Scale bar, 1 m. (D) Energetics of outer membrane fusion. In vitro outer membrane fusion reactions were conducted as described (19) and fusion efficiency isexpressed as a percentage of the standard reaction.
R E S E A R C H A R T I C L E S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1750
membrane fusion was abolished. Mitochondrialouter membrane fusion was highly sensitive tonigericin but significantly less sensitive to vali-nomycin, indicating that proton gradient wasrequired for efficient mitochondrial outer mem-brane fusion.
Our data indicate that outer and innermembrane fusion events were separable andmechanistically distinct. Outer membrane fu-sion required mitochondrial concentration,was driven energetically by a relatively low(endogenous) concentration of GTP and wasdependent on the inner membrane proton gra-dient (Fig. 5D). Inner membrane fusion, incontrast, required the hydrolysis of a relative-ly high concentration of GTP and the innermembrane electrical gradient (Fig. 2).
Fzo1 is required for outer membranefusion and influences the efficiency ofinner membrane fusion. Dissection of mito-chondrial fusion into separate outer and innermembrane fusion events provides an experimen-tal framework for determining the exact func-tions of the fusion proteins. Given our funda-mental knowledge of membrane fusion events, itseems likely that outer and inner membrane fu-sion are products of active mechanisms resultingfrom trans interactions between fusion compo-nents on opposing mitochondria (23). The an-cient and highly conserved transmembrane GT-Pase, Fzo1, is an excellent candidate for medi-ating outer membrane fusion.
To assess whether Fzo1 was required dur-ing fusion in trans, both heterozygous andhomozygous fzo1 mitochondrial mutant reac-tions were analyzed. In both heterozygousand homozygous �fzo1 reactions, both outer
and inner membrane fusion was completelyabolished. However, these defects may havebeen the result of indirect phenotypes associ-ated with �fzo1 cells. Specifically, the loss ofFzo1 function in cells secondarily causes aloss of mitochondrial DNA and consequentlygreatly reduces mitochondrial membrane po-tential, which is essential for mitochondrialfusion (4) (Fig. 2). To assess more directlythe role of Fzo1 in fusion, we used the hypo-morphic, recessive, temperature-sensitivefzo1-1 allele. Both mitochondrial tubules andmitochondrial DNA in yeast cells harboringthe hypomorphic fzo1-1 allele can be main-tained at permissive temperature, but aftershifting to nonpermissive temperature, mito-chondria rapidly fragment as a result of ablock in mitochondrial fusion (4).
To analyze fzo1-1 reactions, both EM anal-ysis and the fluorescence-based assays for mi-tochondrial outer and inner membrane fusionwere used (Table 1). Wild-type mitochondriaexposed to nonpermissive temperatures beforeor during some of the experimental steps instage 1 were unable to fuse. Thus, to analyzethe role of Fzo1, the concentration and incuba-tion steps were performed at permissive tem-perature and mitochondria were placed at anonpermissive temperature after resuspensionin reactions lacking the energy regenerationsystem and NTPs (for stage 1) or containing theenergy regeneration system and NTPs (forstage 2) and incubated for 60 min.
In homozygous fzo1-1 stage 1 reactions,mitochondrial outer membrane fusion wassignificantly compromised under both per-missive and nonpermissive conditions, com-
pared with that of the wild type, as assessedby both fluorescence and EM analysis (Table1). It is likely that Fzo1-1 protein retainedpartial function in vitro under nonpermissiveconditions, explaining why outer membranefusion was not completely abolished. Signif-icantly, mitochondrial outer membrane fu-sion was equally compromised in heterozy-gous fzo1-1 stage 1 reactions under nonper-missive conditions as compared with that ofthe wild type. These findings indicate thatFzo1-Fzo1 interactions on opposing mito-chondrial membranes were required to pro-mote outer membrane fusion.
We also asked whether Fzo1 function wasrequired for inner membrane fusion by assayingmatrix content mixing in homozygous and het-erozygous fzo1-1 reactions under stage 2 condi-tions (Table 1). At permissive temperature, mi-tochondrial outer membrane fusion was affectedto a greater extent than inner membrane fusion,indicating that the relatively high NTP concen-tration present during stage 2 partially sup-pressed the outer membrane fusion defect ob-served in stage 1 fzo1-1 reactions. At nonpermis-sive temperature, both mitochondrial inner andouter membrane fusion were severely compro-mised by the loss of Fzo1 function in heterozy-gous and homozygous reactions, as comparedwith the inner and outer membrane fusion of thewild type. Defects in outer and inner membranefusion were suppressed in fzo1-1 mitochondriaisolated from fzo1-1 cells expressing wild-typeFzo1, indicating that they were the result ofcompromised Fzo1 function. The severe defectin inner membrane fusion observed in fzo1-1mitochondria at nonpermissive temperature sug-gests that Fzo1 trans interactions in the outermembrane were also required for inner mem-brane fusion.A model for mitochondrial fusion. Mi-
tochondrial fusion is accomplished throughsequential mitochondrial outer and innermembrane fusion events that are mediated byseparate and mechanistically distinct machin-eries. Outer membrane fusion requires GTPand trans Fzo1 interactions on opposing mi-tochondria, suggesting that GTP promotesouter membrane fusion by means of Fzo1.The conserved Fzo1 cytosolic C-terminal do-main forms an intermolecular dimeric antipa-rallel coiled-coil structure (24), suggesting amechanism for bringing opposing outermembranes into close proximity. The onlyknown fusion protein associated with the in-ner membrane is the DRP Mgm1. Thus, it isprobable that additional components will berequired in the inner membrane to mediatethe critical steps of membrane associationand fusion pore formation.
Although outer and inner membrane fusioncan be uncoupled, interactions between Fzo1and inner membrane fusion proteins, such asMgm1, play important roles in inner membranefusion. Biochemical interactions between Fzo1
Table 1. Mitochondrial outer and inner membrane fusion of fzo1-1 mitochondria relative to that of thewild-type (WT) control.When fluorescence was used, outer membrane fusion was quantified after stage 1 bydetermining the number of mitochondria with an om-GFP–labeled outer membrane surrounding doublylabeled but nonoverlapping dsRED- and BFP-labeled matrix compartments and dividing by the total numberof mitochondria analyzed. When EM was used, outer membrane fusion was quantified after stage 1 bydetermining the number of mitochondrial pairs that were reciprocally deformed and surrounded by acontinuous outer membrane. A significant number of these structures was observed in input mitochondriaused in the fusion assays (27% of wild type, n � 500). Inner membrane fusion was quantified after stage 2by determining the number of mitochondria labeled with overlapping dsRED- and GFP-labeled matrixcompartments and dividing by the total number of mitochondria analyzed. Absolute percentages are indicatedin parentheses for wild-type reactions for each assay and condition. Temp., temperature.
Type of mitochondriaTemp.(°C)
Outer membrane fusionInner membrane
fusion
Fluorescence(%)
EM (%)Fluorescence
(%)
WT � WT 22° 100(9.2%, n � 600)
100(6.3%, n � 300)
100(12%, n � 300)
WT � WT 37° 100(8.8%, n � 400)
100(6.4%, n � 300)
100(11.8%, n � 400)
fzo1-1 � fzo1-1 22° 13(n � 600)
64(n � 800)
88(n � 300)
fzo1-1 � fzo1-1 37° 14.5(n � 400)
41(n � 600)
5.5(n � 200)
fzo1-1 � WT 22° 16(n � 600)
60(n � 300)
92(n � 200)
fzo1-1 � WT 37° 16(n � 400)
52(n � 300)
24(n � 300)
R E S E A R C H A R T I C L E S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1751
and Mgm1 have been demonstrated and in-volve the outer membrane fusion protein Ugo1(7, 8). The exact nature of the interactions be-tween Fzo1, Ugo1, and Mgm1 and their specif-ic roles in mitochondrial fusion remain largelyunknown. However, Ugo1 functions as anadaptor between Fzo1 and Mgm1 (18). Fzo1interactions with inner membrane componentsmay be required in a mechanical manner for theformation of regions of close inner and outermembrane contact within mitochondria. Suchregions of contact would function to bring innermembranes into closer proximity after outermembrane fusion and also perhaps to eliminatecristae in the vicinity of fusion. Indeed, by EManalysis, no cristae are observed at sites of innermembrane contact (Fig. 4B). Alternatively, butnot exclusively, Fzo1 may function in a regu-latory manner by stimulating, by means of GTPcycle–dependent conformations, events in theinner membrane required for fusion.
Fzo1 is a key player in the evolution ofmitochondrial fusion. Based on a phylogeneticanalysis, Fzo1 is derived from the eubacterialendosymbiotic precursor of mitochondria (10,11). Our data showing that Fzo1 plays essentialand fundamental roles in the fusion of both outerand inner membranes are consistent with thisidea. Phylogenetic analysis of Fzo1 also identi-fies it as a member of the dynamin-related GT-Pase family (11). The similarity of Fzo1 to DRPssuggests the intriguing possibility that DRPsevolved from a eubacterial progenitor, and thatFzo1, like DRPs, functions to remodel mem-branes through self-interaction and assembly. An
additional evolutionary connection betweenDRPs and endosymbiotic organelles is that theirdivision also has evolved to require the action ofa DRP (25).
DRPs most commonly have been shown tofunction in membrane fission events, such asmitochondrial and chloroplast division and en-docytosis (26). However, the actions of twoDRPs, Fzo1 on the outer membrane and Mgm1on the inner membrane, are required for mito-chondrial membrane fusion. In a fusion event,Fzo1 and Mgm1 may possess modified activitiesand function through self-assembly only to tu-bulate, and not divide, regions of outer and innermembrane, thereby creating a bending stress,which can be harnessed for membrane fusion.The utilization of DRPs to drive membrane fu-sion events mechanistically distinguishes mito-chondrial fusion from other fusion events ineukaryotic cells. Understanding their exact modeof action will enhance our understanding of thefundamental principles that underlie membranefusion events.
References and Notes1. J. Nunnari et al., Mol. Biol. Cell 8, 1233 (1997).2. H. Sesaki, R. E. Jensen, J. Cell Biol. 152, 1123 (2001).3. R. Belenkiy, A. Haefele, M. B. Eisen, H. Wohlrab,
Biochim. Biophys. Acta 1467, 207 (2000).4. G. J. Hermann et al., J. Cell Biol. 143, 359 (1998).5. D. Rapaport,M. Brunner,W. Neupert, B.Westermann,
J. Biol. Chem. 273, 20150 (1998).6. E. D. Wong et al., J. Cell Biol. 151, 341 (2000).7. E. D. Wong et al., J. Cell Biol. 160, 303 (2003).8. H. Sesaki, S. M. Southard, M. P. Yaffe, R. E. Jensen,
Mol. Biol. Cell 14, 2342 (2003).9. S. Fritz, D. Rapaport, E. Klanner, W. Neupert, B. Wes-
termann, J. Cell Biol. 152, 683 (2001).
10. More information about Fzo1 is available athttp://db.yeastgenome.org/cgi-bin/SGD/homolog/nrHomolog?locus�YBR179C#summary.
11. G. J. Praefcke, H. T. McMahon, Nature Rev. Mol. CellBiol. 5, 133 (2004).
12. S. Frank et al., Dev. Cell 1, 515 (2001).13. M. Karbowski et al., J. Cell Biol. 159, 931 (2002).14. M. Karbowski et al., J. Cell Biol. 164, 493 (2004).15. C. Alexander et al., Nature Genet. 26, 211 (2000).16. C. Delettre et al., Nature Genet. 26, 207 (2000).17. S. Zuchner et al., Nature Genet. 36, 449 (2004).18. H. Sesaki, R. E. Jensen, J. Biol. Chem. 279, 28298 (2004).19. Materials and methods are available as supporting
material on Science Online.20. Addition of the reduced form of nicotinamide ade-
nine dinucleotide to apyrase-treated mitochondriadid not restore fusion, indicating that the effect ofapyrase was due to NTP depletion and not dissipationof inner membrane potential.
21. F. Legros, A. Lombes, P. Frachon, M. Rojo, Mol. Biol.Cell 13, 4343 (2002).
22. V. R. Simon, T. C. Swayne, L. A. Pon, J. Cell Biol. 130,345 (1995).
23. R. Jahn, T. Lang, T. C. Sudhof, Cell 112, 519 (2003).24. T. Koshiba et al., Science 305, 858 (2004).25. C. E. Caldon, P. E.March, Curr. Opin. Microbiol. 6, 135
(2003).26. K.W. Osteryoung, J. Nunnari, Science 302, 1698 (2003).27. We thank F. McNally, M. Paddy, T. Powers, S. Scott,
and S. Theg for helpful discussions and comments onthe manuscript and A. Cassidy-Stone for experimen-tal assistance. Supported by grants from the NSF(MCB-0110899) and NIH (R01-GM62942A) to J.N.
Supporting Online Materialwww.sciencemag.org/cgi/content/full/1100612/DC1Materials and MethodsFigs. S1 and S2ReferencesMovies S1 to S3
24 May 2004; accepted 23 July 2004Published online 5 August 2004;10.1126/science.1100612Include this information when citing this paper.
REPORTSTwo-Step Synthesis of
Carbohydrates by SelectiveAldol Reactions
Alan B. Northrup and David W. C. MacMillan*
Studies of carbohydrates have been hampered by the lack of chemical strategiesfor the expeditious construction and coupling of differentially protectedmonosaccharides. Here, a synthetic route based on aldol coupling of threealdehydes is presented for the de novo production of polyol differentiatedhexoses in only two chemical steps. The dimerization of �-oxyaldehydes, cat-alyzed by L-proline, is then followed by a tandem Mukaiyama aldol addition-cyclization step catalyzed by a Lewis acid. Differentially protected glucose,allose, and mannose stereoisomers can each be selected, in high yield andstereochemical purity, simply by changing the solvent and Lewis acid used. Thereaction sequence also efficiently produces 13C-labeled analogs, as well asstructural variants such as 2-amino– and 2-thio–substituted derivatives.
Hexose carbohydrates play vital roles in bio-logical processes as diverse as signal trans-duction, cognition, and the immune response.
However, the study of this fundamental classof bioarchitecture has been hindered by thepaucity of chemical methods for the efficient
synthesis and coupling of hexose systems toform polysaccharides and other derivatives(1). Specifically, the challenge in selectivelylinking and functionalizing these monosac-charides lies in distinguishing among theirfive chemically similar hydroxyl groups.During the last century, chemists have fo-cused on using iterative alcohol protection-deprotection strategies, an approach that typ-ically requires 8 to 14 chemical steps (1, 2).While the abundant and inexpensive supplyof native carbohydrates may render such astrategy intuitively attractive, we felt that a denovo enantioselective synthesis of differen-tially protected hexoses might provide a moreefficient approach (3–10). The appeal of thisstrategy is that fragments of the hexose canbe independently derivatized (isotopically or
Department of Chemistry, California Institute ofTechnology, 1200 East California Boulevard, Pasade-na, CA 91125, USA.
*To whom correspondence should be addressed.E-mail: [email protected]
R E S E A R C H A R T I C L E S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1752
functionally) before assembly of the mole-cule; thus, there is no longer a need to chem-ically discriminate between similar groups ona hexose framework.
In this context, the aldol reaction has beenapplied to the synthesis of carbohydrates on afew occasions; however, the need for iterativeoxidation-state adjustments has thus far preclud-ed a broadly used or step-efficient protocol.From a conceptual standpoint, a two-step carbo-hydrate synthesis can be envisioned based on aniterative aldol sequence using simple �-oxyalde-hydes. While the approach is attractive in theory,the practical execution of this synthetic strategyrequires two unproven aldol applications: (i) anenantioselective aldol union of �-oxyaldehydesubstrates (Aldol Step 1, Fig. 1A) and (ii) adiastereoselective aldol coupling betweentri-oxy–substituted butanals and an �-oxyalde-hyde enolate (Aldol Step 2, Fig. 1B). In thisreport, we describe the successful develop-ment of both such aldol reactions for thetwo-step synthesis of enantioenriched, polyol-differentiated hexoses.
The first step in our synthetic scheme (AldolStep 1) is a stereoselective �-oxyaldehydedimerization. Beyond the traditional demands ofenantio- and diastereocontrol, the reaction re-quires that the �-oxyaldehyde reagent 1 partici-pate as both a nucleophile and an electrophile,whereas the product 2, also an �-oxyaldehyde,must not perform as either (Fig. 1A). Recently,we disclosed an organocatalytic strategy thatuses L-proline for the regio-, diastereo-, andenantioselective aldol cross-coupling of�-alkyl– bearing aldehydes (11–16). Nota-bly, the aldehyde-containing products of thisreaction do not participate in further aldolchemistry. With this in mind, we attemptedto extend this methodology to the couplingof �-oxygenated aldehydes (Fig. 1A).
As shown in Fig. 2, the proline catalyzed�-oxy aldol (Step 1 results) does providedirect and enantioselective access to differen-tially protected anti-1,2 triols. Specifically,exposure of �-triisopropylsilyloxy-acetalde-hyde to 10 mol% L-proline at room temper-ature readily provides enantioenriched [95%enantiomeric excess (ee)] �,�-oxy–protectedL-erythrose 3, whereas the corresponding re-action of �-benzyloxyacetaldehyde leads tothe dimeric aldol adduct 4 in 98% ee. Asrequired, the �-oxyaldehyde products of thisnew aldol protocol are inert to further pro-line-catalyzed enolization or enamine addi-tion. We recently published a report outliningthe scope and limitations of this �-oxyalde-hyde dimerization (17).
Having succeeded in our first step, wenext focused on adding the third aldehydebuilding block and achieving cyclization.Given that �-hydroxy aldehydes (the prod-ucts of Step 1) are relatively inert to enam-ine addition, we focused instead uponLewis acid activation for the second aldol
coupling. Specifically, we reasoned that aMukaiyama aldol reaction between an�-oxy-enolsilane 5 and a trioxy-aldehyde 2(the product of Aldol Step 1) might gener-ate a hexose-oxocarbenium intermediate 6that would rapidly undergo cyclization toform the carbohydrate ring system (Fig.1B). This tandem aldol addition and cy-clization presents two selectivity issues: (i)The chemoselective preference for the oxo-carbenium 6 to undergo cyclization in lieu
of further aldol addition and (ii) the diaste-reoselective construction of two new oxy-stereocenters in the carbon-carbon bond–forming step, which ultimately defines theextent to which one carbohydrate isomer isgenerated in preference to another (e.g.,allose versus altrose versus glucose versusmannose; see Fig. 2).
We first examined the use of the triiso-propylsilyl (TIPS)-protected �-oxy aldehyde3 (Aldol Step 1 product) and the �-acetoxy-
Fig. 1. (A) Step 1: Proline-catalyzed enantioselective dimerization of �-oxyaldehydes. (B) Step 2:Mukaiyama aldol-carbohydrate cyclization.
Fig. 2. Step 1 Results: The enantioselective dimerization of �-oxyaldehydes. Step 2 Results: TheLewis acid–mediated Mukaiyama aldol-carbohydrate cyclization.
R E P O R T S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1753
enolsilane 7 in the presence of Lewis acidicsalts such as MgBr2�OEt2 or TiCl4 (Fig. 2,Step 2 results). Preliminary studies revealedthat this second aldol reaction does providepolyol-differentiated hexose carbohydrates inexcellent yields and diastereoselectivities (dr)(18). More important, selective access to ei-ther glucose, mannose, or allose can be ac-complished by judicious choice of Lewis acidand reaction solvent.
For example, the use of MgBr2�OEt2 in sol-vents such as ether, toluene, or pentane affordshigh levels of selectivity for glucose 8 (8:1 to10:1), whereas the analogous reaction in dichlo-romethane is selective for mannopyranose 9.Using optimized conditions, we obtained a 79%yield and a 10:1 preference for glucose in di-ethyl ether, whereas we observed an 87% yieldand �19:1 selectivity for mannose in dichlo-romethane (Fig. 2). The origins of this dramaticchange in isomer selectivity as a function ofreaction solvent reflect the capacity of the reac-tion medium to dictate which face of the enolsi-lane reacts with the aldehyde. Furthermore, ex-
posure of the same aldehyde and enolsilane com-ponents 3 and 7 to TiCl4 leads to the selectiveformation of the allose carbohydrate isomer in�19:1 selectivity, 97% yield, and 95% ee. Inthis latter case, we have determined that theenolsilane undergoes transmetallation to gener-ate a titanium-enolate before the Aldol Step 2event. We propose that this metalloenolate par-ticipates in a cyclic (closed) transition state withthe Felkin diastereoface of the aldehyde, where-as the magnesium reactions involve addition ofthe enolsilane to the opposite (non-Felkin) alde-hyde face. We note that the unnatural (L) form ofcarbohydrates 8, 9, and 10 could be accessedselectively by using the alternate (D) enantiomerof proline in the Aldol Step 1.
Having developed this methodology, we ap-plied our reaction sequence to the preparationof 13C6-labeled hexoses. Specifically, we pro-duced fully 13C-labeled, differentially protectedD-glucose 11, D-mannose 12, and D-allose 13derivatives in only four linear steps from 13C2-ethylene glycol (19), in overall yields of 33%,35%, and 43%, respectively.
Our route to differentiated hexoses is alsoamenable to considerable structural variation inboth the enolsilane reagent and the �-oxyalde-hyde component (Table 1). This critical featurein reaction versatility allows the rapid construc-tion of hexoses that can be directly used in thesynthesis of di- or polysaccharides. For example,carbohydrates that contain participating or non-participating groups at the C(2) position arereadily accessed by using the respective acyloxy-or benzyloxy-substituted enolsilanes (Table 1,entry 1, A � OBn, 83% yield, �19:1 alloseselective; entry 4, A � OAc, 96% yield, �19:1allose selective). Such hexose systems have es-tablished utility as either �- or �-coupling part-ners in polysaccharide synthesis (1, 2). The mod-ular nature of the Aldol Step 1 also allows forbroad diversification of substituents at the car-bohydrate C(4) and C(6) positions (10, 16). Forexample, the incorporation of TIPS-protectingand tertiary-butyldiphenylsilyl (TBDPS)–pro-tecting groups at these sites is readily accom-plished (Table 1, entries 4 and 5, 86 to 96%yield, �19 :1 dr, �95% ee). These protect-ing groups can be selectively removed fromthe C(6) position, thereby affording carbo-hydrates that are differentially protected ateach hydroxyl site. As such, these versatilesaccharide monomers can be rapidly manip-ulated to expose the C(2), C(3), C(4), orC(6) hydroxyl groups, an important consid-eration for di- or polysaccharide couplings.
The reaction sequence also allows rapid ac-cess to a wide variety of unnatural carbohydratesthat substitute carbon, nitrogen, and sulfurgroups for the native hydroxy constituents. Theanalogous reactions using amino- and thio-sub-stituted enolsilanes provide the mannose archi-tecture in high selectivity, affording the 2-tert-butylcarba-moylmannose derivative 15 (Table 1,entry 2) in 74% yield and 10:1 diastereocontroland the 2-acetylmercaptomannose product 16(Table 1, entry 3) in 71% yield and �19:1mannose selectivity. Carbogenic substituents canalso be introduced at the saccharide C(4) posi-tion in the case where �-alkyl and �-oxy alde-hydes were cross-coupled in the Step 1 Aldolevent (Table 1, entry 6, 68% yield, �19:1 dr,99% ee). The capacity to selectively buildknown carbohydrates with single-point atomicmutations will enable medicinal chemists to rap-idly study structure activity relationships (SAR)on mono-, di-, and polysaccharide templates.
Our strategy for the synthesis of differentiallyprotected hexoses thus provides rapid enantiose-lective access to key building blocks in saccha-ride and polysaccharide synthesis. Furthermore,our approach efficientlyyields isotopic and func-tional variants of the hexoses that have not beenreadily accessible for pharmaceutical study.
References and Notes1. B. Ernst, G. W. Hart, P. Sinay, Eds., Carbohydrates in
Chemistry and Biology (Wiley-VCH, New York, 2000).2. K. C. Nicolaou, N. J. Bockovich, in Bioorganic Chem-
Table 1. Representative two-step enantioselective carbohydrate synthesis. Temperature refers to thefinal temperature of the reaction mixture after being warmed from –78°C. Yield refers to the combinedyield of diastereomers. Diastereoselectivity (dr) was determined by proton nuclear magnetic resonance(1H NMR) integration of the reaction mixture. Entry 4 was performed with TiCl4.
R E P O R T S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1754
istry: Carbohydrates, S. M. Hecht, Ed. (Oxford Univ.Press, New York, 1999), pp. 134–173.
3. P. Vogel, in Glycoscience, B. O. Fraser-Reid, K. Tat-suta, J. Thiem, Eds. (Springer, Berlin, 2001), vol. 2, pp.1023–1174.
4. S. Y. Ko, A. W. M. Lee, S. Masamune, L. A. Reed, K. B.Sharpless, Science 220, 949 (1983).
5. S. J. Danishefsky, C. J. Maring, J. Am. Chem. Soc. 107,7761 (1985).
6. D. L. Boger, K. D. Robarge, J. Org. Chem. 53, 5793 (1988).7. L. F. Tietze, A. Montenbruck, C. Schneider, Synlett.
1994, 509 (1994).8. M. Takeuchi, T. Taniguchi, K. Ogasawara, Synthesis
1999, 341 (1999).9. C. Bataille et al., J. Org. Chem. 67, 8054 (2002).
10. S. G. Davies, R. L. Nicholson, A. D. Smith, Synlett.2002, 1637 (2002).
11. A. B. Northrup, D.W. C. MacMillan, J. Am. Chem. Soc.124, 6798 (2002).
12. M. Movassaghi, E. N. Jacobsen, Science 298, 1904(2002).
13. B. List, Tetrahedron 58, 5573 (2002).14. B. List, R. A. Lerner, C. F. Barbas, III, J. Am. Chem. Soc.
122, 2395 (2000).15. Z. G. Hajos, D. R. Parrish, J. Org. Chem. 39, 1615
(1974).16. U. Eder, G. Sauer, R. Wiechert, Angew. Chem. Int. Ed.
Engl. 10, 496 (1971).17. A. B. Northrup, I. K. Mangion, F. Hettche, D. W. C.MacMillan, Angew. Chem. Int. Ed. Engl. 43, 2152(2004).
18. For an example of Lewis base–catalyzed aldol reac-tions using trichlorosilylenolethers, see (20).
19. It should be noted that both the labeled enolsilane andTIPS dimer precursor were available in gram quantitiesfrom only 1.00 g of ethylene glycol ($31/mmol).
20. S. E. Denmark, S. K. Ghosh, Angew. Chem. Int. Ed., 40,4759 (2001).
21. Financial support was provided by the NIH NationalInstitute of General Medical Sciences (R01GM66142-01) and gifts from Bristol-Myers Squibb,Johnson and Johnson, Eli Lilly, and Merck ResearchLaboratories. D.W.C.M. is grateful for support fromthe Camille and Henry Dreyfuss Foundation, theSloan Foundation, and Research Corporation underthe Cottrell Scholarship and Research Innovation pro-grams. A.B.N. is grateful for an NSF predoctoral fel-lowship.
Supporting Online Materialwww.sciencemag.org/cgi/content/full/1101710/DC1Materials and Methods
21 June 2004; accepted 22 July 2004Published online 12 August 2004;10.1126/science.1101710Include this information when citing this paper.
A Stable Compound Containing aSilicon-Silicon Triple Bond
Akira Sekiguchi,* Rei Kinjo, Masaaki Ichinohe
The reaction of 2,2,3,3-tetrabromo-1,1,4,4-tetrakis[bis(trimethylsilyl)methyl]-1,4-diisopropyltetrasilane with four equivalents of potassium graphite (KC8) intetrahydrofuran produces 1,1,4,4-tetrakis[bis(trimethylsilyl)methyl]-1,4-diiso-propyl-2-tetrasilyne, a stable compound with a silicon-silicon triple bond, whichcan be isolated as emerald green crystals stable up to 100°C in the absence ofair. The Si Si triple-bond length (and its estimated standard deviation) is2.0622(9) angstroms, which shows half the magnitude of the bond shorteningof alkynes compared with that of alkenes. Unlike alkynes, the substituents atthe Si Si group are not arranged in a linear fashion, but are trans-bent witha bond angle of 137.44(4)°.
Hydrocarbons containing C�C doublebonds (alkenes) and C C triple bonds(alkynes) form an abundant and structurallydiverse class of organic compounds. How-ever, the ability of heavier congeners ofcarbon (where element E is Si, Ge, Sn, andPb) to form double bond of the type�E�E� and triple bond of the type -E E-was for a long time doubted (1–4). The firstattempts to generate such species were un-successful, resulting in the formation ofpolymeric substances. This led to the often-cited “double-bond rule”: Those elementswith a principal quantum number equal toor greater than three are not capable offorming multiple bonds because of the con-siderable Pauli repulsion between the elec-trons of the inner shells (5–7). Such aviewpoint prevailed despite the accumula-tion of a vast amount of experimental datasupporting the existence of multiply bond-ed species as reactive intermediates (1–4).This conflict was resolved nearly 30 yearsago, when Lappert and Davidson report-
ed the synthesis of the stable distannene[(Me3Si)2CH] 2Sn�Sn[CH(SiMe3) 2] 2,where Me is methyl, which has a Sn�Sn
double bond in the solid state (8). The nextimportant discoveries came from two re-search groups in 1981: West and colleaguesreported the synthesis of a stable compoundwith a Si�Si double bond, tetramesityldi-silene (9), and Brook et al. synthesized acompound with a Si�C double bond (10).As for triple bonds, Power and co-workersrecently prepared alkyne analogs of theheavier group 14 elements: germanium, tin,and lead (11–13). However, despite bearingnominal triple bonds, these compounds ac-tually exhibited a highly pronounced non-bonding electron density character at thecentral atoms, resulting in a decrease in thebond order on descending group 14 (14,15). In light of these results, isolation of thesilicon analog of alkynes has been a com-pelling goal. Although the theoretical anal-ysis predicted the experimental accessibil-ity of disilynes with a silicon-silicon triple
Department of Chemistry, Graduate School of Pureand Applied Sciences, University of Tsukuba, Tsukuba,Ibaraki 305–8571, Japan.
*To whom correspondence should be addressed. E-mail: [email protected]
Reaction 1.
Fig. 1.Molecular struc-ture of 1,1,4,4-tet-rakis[bis(trimethyl-silyl)methyl]-1, 4-di-isopropyl-2-tetrasilyne(2) (30% probabilityellipsoids for Si andC). Selected bondlengths (Å): Si1–Si1’ �2.0622(9), Si1–Si2 �2.3698(6), Si2–C1 �1.9119(15), Si2–C8 �1.9120(15), and Si2–C15 � 1.9180(16).Selected bond angles(°): Si1’–Si1–Si2 �137.44(4), Si1–Si2–C1� 108.97(5), Si1–Si2–C8 � 108.38(5), Si1–Si2–C15 � 106.47(5), C1–Si2–C8 � 106.83(6), C8–Si2–C15 � 114.77(7), andC1–Si2–C15 � 111.30(7). Estimated standard deviations are in parentheses.
R E P O R T S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1755
bond (16), all attempts to isolate suchpostulated molecules have been unsuccess-ful (17–19). The difficulty in synthesizingdisilynes is due in large part to their highreactivities, especially toward isomeriza-tion and dimerization.
We report the isolation and full char-acterization of 1,1,4,4-tetrakis[bis(trimethyl-silyl)methyl]-1,4-diisopropyl-2-tetrasilyne 2,a stable disilyne R-Si Si-R, which is the Sianalog of an alkyne. In this compound, theSi Si triple bond is kinetically and thermo-dynamically stabilized by two large silylsubstituents, each bearing one isopropyland two bis(trimethylsilyl)methyl groups.The compound is accessed by reduction of atetrabrominated precursor. Thus, the reactionof 2,2,3,3-tetrabromo-1,1,4,4-tetrakis[bis(tri-methylsilyl)methyl]-1,4-diisopropyltetrasi-lane 1 with four equivalents of potassiumgraphite (KC8) in dry tetrahydrofuran (THF)produces a dark green mixture, from whichdisilyne 2 can be isolated as extremely air-and moisture-sensitive emerald green crystalsin 73% isolated yield (Reaction 1) (20, 21).Despite the large steric congestion, the debro-mination reaction proceeds rapidly and clean-ly. The disilyne 2 was purified by recrystalliza-tion from pentane at –30°C; it has a decomposi-tion point of 127° to 128°C. No evidence for theisomerization of 2 to RRSi�Si or dissociationinto the two RSi fragments (where R isSiiPr[(CH(SiMe3)]2 and iPr is isopropyl) wasobserved, indicating that the two central Si at-oms are strongly bonded.
The disilyne 2 was fully characterized spec-troscopically; the most informative data camefrom 29Si nuclear magnetic resonance (NMR)studies. Four equal-intensity resonance signals atthe chemical shifts � � –0.3, 0.0, 20.7, and 89.9parts per million (ppm) were observed in the 29SiNMR spectrum, assigned as follows: The peak at89.9 ppm corresponds to a triply bonded Siatom, the peak at 20.7 ppm corresponds to Siatoms bonded to the Si Si group, and peaks at–0.3 and 0.0 ppm correspond to the fourCH(SiMe3)2 groups (21). The resonance of thesp-hybridized Si atoms is shifted upfield com-pared with that of silyl-substituted disilenes (� �142.1 to 154.5 ppm) (22), as was observed in thecase of 13C NMR chemical shifts of silyl-substi-
tuted alkenes (� � 188 to 197 ppm) and alkynes(� � 112 to 114 ppm) (23).
The solid state structure of 2 was confirmedby x-ray crystallographic analysis (Fig. 1). Fullmetrical parameters are listed in table S3(24). The four Si atoms (Si2, Si1, Si1, andSi2) are perfectly coplanar and the bulkySiiPr[(CH(SiMe3)]2 groups protect the centralSi Si triple bond. The most significant result isthe Si Si triple-bond length of 2.0622(9) Å.This value is 3.8% shorter than typical Si�Sidouble-bond length (2.14 Å) and 13.5% shorterthan the average Si-Si single-bond length of 2.34Å (4). This shortening is half the magnitude ofthat in the carbon counterparts. Moreover,alkynes have a linear geometry around the C Ctriple bond, whereas disilynes have been predict-ed to have a highly pronounced trans-bent ge-ometry around the Si Si triple bond (14, 16).The structure confirms this prediction: The sub-stituents at the Si Si are not arranged in a linearfashion, but are trans-bent with a bond angle of137.44(4)°, as determined by the Si2-Si1-Si1angle. This bond angle is 12.5° smaller than thatcalculated for HSi SiH (124.9°). According totheoretical investigations, substitution by elec-tropositive silyl groups leads to a less trans-bentdisilyne structure (25). The structure of 2 pre-sented here is close to that predicted by a recentdensity functional (DFT) calculation on(tBu3Si)2MeSiSi SiSiMe(SitBu3)2, where tBuis tert-butyl (26).
The space-filling model of 2 shown in Fig. 2highlights the steric protection of the Si Sigroup by the isopropyl and bis(trimethyl-silyl)methyl substituents. Upon replacementof the isopropyl groups in precursor withmethyls, the reaction to produce the disilyneyields a dimerization product instead, bear-ing a tetrasilatetrahedrane core (27).
Despite the steric protection, the Si Sitriple bond in 2 does undergo addition reac-tions with a halogen. Thus, 2 readily reactedwith two equivalents of bromine at roomtemperature in hexane to form 1 in 94% yieldby cleavage of the two �(Si Si) bonds.
A DFT calculation on disilyne 2 at theB3LYP/6-31G(d) level of theory well re-produces the experimental geometry andthe structural parameters (calculated value:2.093 Å for the Si Si bond length, 136.1°for the trans-bending angle). The molecularorbitals (MOs) of 2 calculated at the HF/6-311G(d)//B3LYP/6-31G(d) level presentedin Fig. 3 show two nondegenerate highestoccupied � MOs (HOMO-1 and HOMO)and two lowest unoccupied antibonding �*MOs (LUMO and LUMO�1). The out-of-plane HOMO and LUMO�1 are represent-ed by the pure (pz-pz) � MOs, whereas thein-plane HOMO-1 and LUMO are repre-sented mainly by (py-py) � MOs with aslight contribution from the antibonding �*(Si-Si) orbital of the central bond. In accor-dance with the triple-bond structure, natu-ral bond orbital analysis of 2 shows elec-tron occupation of the two �(Si Si) orbit-als (1.934 and 1.897 electron), indicatingtheir bonding character. The bond order(Wiberg bond index) of Si1-Si1 is 2.618,which agrees with the real Si Si triplebond. The presence of the two nondegen-erate � and two �* MOs in 2 is reflected inthe ultraviolet-visible absorption of 2, asshown in Fig. 4. The strong absorptionbands at wavelengths (�) of 259 and 328nm are due to the two allowed �-�* tran-sitions. The weak absorption bands withmaxima of 483 and 690 nm are probably aresult of forbidden transitions, and the lat-ter very weak one (HOMO-LUMO transi-tion) is responsible for the emerald greencolor of 2.
References and Notes1. R.West, Angew. Chem. Int. Ed. Engl. 26, 1201 (1987).2. G. Raabe, J. Michl, in The Chemistry of Organic Silicon
Compounds, S. Patai, Z. Rappoport, Eds. (Wiley, NewYork, 1989), part 2, chap. 17.
Fig. 2. Space-filling model of 2. Si, red; C, gray;H, white.
Fig. 3. The � MOs of 2 calculated at theHF/6-311G(d)//B3LYP/6-31G(d) level (HOMO-1, HOMO, LUMO, and LUMO�1). E is theenergy level of the orbitals. The large verticalarrow indicates the energy level. The two smallarrows indicate two electrons of opposing spin,referred to as paired electrons.
259 nm
328 nm
483 nm
690 nm
200 400 600 800 1000
1.0
0.5
0.0
X30
ε / 1
04
λ / nm
Fig. 4. Ultraviolet-visible absorption spectrum of2 in hexane at room temperature; � is the molarextinction coefficient (dm3 mol�1 cm�1).
R E P O R T S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1756
3. P. P. Power, Chem. Rev. 99, 3463 (1999).4. M. Weidenbruch, The Chemistry of Organic Silicon
Compounds, Z. Rappoport, Y. Apeloig, Eds. (Wiley,Chichester, UK, 2001), vol. 3, chap. 5.
5. E. Wiberg, Lehrbuch der Anorganischen Chemie, A. F.Holleman, E. Wiberg, Eds. (W. de Gruyter, Berlin,Germany, eds. 22 and 23, 1943).
6. J. Goubeau, Angew. Chem. 69, 77 (1957).7. P. Jutzi, Angew. Chem. Int. Ed. Engl. 14, 232 (1975).8. P. J. Davidson, M. F. Lappert, J. Chem. Soc. Chem.
Commun. 1973, 317 (1973).9. R.West,M. J. Fink, J.Michl, Science 214, 1343 (1981).
10. A. G. Brook, F. Abdesaken, B. Gutekunst, G.Gutekunst, R. K. Kallury, J. Chem. Soc. Chem. Com-mun. 1981, 191 (1981).
11. (2,6-Tip2-C6H3)PbPb(C6H3-2,6-Tip2), where Tip is2,4,6-i-Pr3-C6H2-, is described in L. Pu, B. Twamley,P. P. Power, J. Am. Chem. Soc. 122, 3524 (2000).
12. (2,6-Dipp2-C6H3)SnSn(C6H3-2,6-Dipp2), where Dippis 2,6-i-Pr2-C6H3-, is described in A. D. Philips, R. J.Wright, M. M. Olmstead, P. P. Power, J. Am. Chem.Soc. 124, 5930 (2002).
13. (2,6-Dipp2-C6H3)GeGe(C6H3-2,6-Dipp2)2 is de-scribed in M. Stender, A. D. Phillips, R. J. Wright, P. P.Power, Angew. Chem. Int. Ed. Engl. 41, 1785 (2002).
14. P. P. Power, Chem. Commun. 2003, 2091 (2003).15. G. H. Robinson, Acc. Chem. Res. 32, 773 (1999).16. S. Nagase, K. Kobayashi, N. Takagi, J. Organomet.
Chem. 611, 264 (2000).17. A. Sekiguchi, S. S. Zigler, R. West, J. Am. Chem. Soc.
108, 4241 (1986).18. R. Pietschnig, R. West, D. R. Powell, Organometallics
19, 2724 (2000).19. The reduction of (tBu3Si)2MeSiClSi�SiClSiMe(SitBu3)2
with lithium naphthalene in THF has recently been report-ed (28). This contains an unstable product with a low field29Si NMR signal at � � 91.5 ppm, which was ascribed toa Si Si triple-bond resonance.
20. Crystals of 1 (100 mg, 0.087 mmol) and KC8 (50 mg,0.370 mmol) were placed in a glass tube and de-gassed. Dry oxygen-free THF (2 ml) was introducedby vacuum transfer and the mixture was allowed towarm from –78°C to room temperature overnightwith stirring. The solution turned an intense greencolor. The solvent was replaced by hexane, and thenthe resulting potassium salt and graphite were fil-tered off in a glove box (a box equipped with glovesin which air- and moisture-sensitive compounds canbe handled). After evaporation of the solvent, pen-tane was added and the solution was cooled at –30°Cto give emerald green crystals of 2 (53 mg, 73%).
21. NMR of 2 ([D6]benzene solution, 1H) � values (ppm): –0.01(singlet, 4H), CH protons; 0.39 (singlet, 36H), SiMe3 pro-tons; 0.57 (singlet, 36H), SiMe3 protons, 1.44 (doublet, 12H,spin-spin coupling constant J � 6.0 Hz, 12H), isopropylmethyl protons, 1.49 (septet, spin-spin coupling constantJ � 6.0 Hz, 2H), isopropyl methyne proton. NMR (13C) �values: 5.1, 5.7, 8.9, 17.8, and 22.3. NMR (29Si) � values:–0.3, 0.0, 20.7, and 89.9. High-resolution mass spectrum:mass-to-charge ratio (m/z) calculated for C34H90Si12 to be834.4274, experimentally found to be 834.4275. Ultravio-let-visible spectrum (in hexane solution): �max [wavelength,molar extinction coefficient (�)/dm3 mol�1 cm�1] 259,10300; 328, 5800; 483, 120; and 690, 14.
22. M. Kira, T. Maruyama, C. Kabuto, K. Ebata, H. Sakurai,Angew. Chem. Int. Ed. Engl. 33, 1489 (1994).
23. H. Sakurai, H. Tobita, Y. Nakadaira, Chem. Lett. 1982,1251 (1982).
24. An emerald green crystal (approximate dimensions,0.30 by 0.15 by 0.15 mm) of 2 was used for the x-raydiffraction data collection on a Mac ScienceDIP2030K Image Plate Diffractometer with graphite-monochromatized Mo–K� radiation (� � 0.71070 Å).Cell constants and an orientation matrix for datacollection corresponded to the monoclinic spacegroup C2/c, with a � 30.9620(11) Å, b � 10.9060(2)Å, c � 18.1170(7) Å, � � 118.995(2)°, V� 5350.8(3)Å3, four molecules per unit cell, formular weight836.14, and calculated density 1.038 Mg/m3. Datawere collected at 120 K, � range from 2.18° to28.01°. There were 26,993 collected reflections(6412 unique, Rint � 0.0290); R1 � 0.0373 for 5479reflections with I � 2�(I), wR2 � 0.1096 for allreflections. More crystallographic data are available
at the Cambridge Crystallographic database, acces-sion code and deposition no. CCDC 245523.
25. K. Kobayashi, S.Nagase, Organometallics 16, 2489 (1997).26. N. Takagi, S. Nagase, Eur. J. Inorg. Chem. 2002, 2775
(2002).27. M. Ichinohe, M. Toyoshima, R. Kinjo, A. Sekiguchi,
J. Am. Chem. Soc. 125, 13328 (2003).28. N. Wiberg, W. Niedermayer, G. Fischer, H. Noth, M.
Suter, Eur. J. Inorg. Chem. 2002, 1066 (2002).29. Supported by a Grant-in-Aid for Scientific Research
(Nos. 134078204, 16205008, and 16550028) fromthe Ministry of Education, Science and Culture ofJapan, and Center of Excellence program.We thank S.Nagase for helpful discussions and advice.
Supporting Online Materialwww.sciencemag.org/cgi/content/full/305/5691/1755/DC1Tables S1 to S5
30 June 2004; accepted 2 August 2004
A Linear, O-Coordinated �1-CO2
Bound to UraniumIngrid Castro-Rodriguez, Hidetaka Nakai, Lev N. Zakharov,
Arnold L. Rheingold, Karsten Meyer*
The electron-rich, six-coordinate tris-aryloxide uranium(III) complex[((AdArO)3tacn)UIII] [where (AdArOH)3tacn � 1,4,7-tris(3-adamantyl-5-tert-butyl-2-hydroxybenzyl)1,4,7-triazacyclononane] reacts rapidly with CO2 to yield[((AdArO)3tacn)UIV(CO2)], a complex in which the CO2 ligand is linearly coordinatedto the metal through its oxygen atom (�1-OCO). The latter complex has beencrystallographically and spectroscopically characterized. The inequivalent O–C–Obond lengths [1.122 angstroms (Å) for the O–C bond adjacent touranium and 1.277Å for the other], considered together with magnetization data and electronic andvibrational spectra, support the following bonding model: UIV�O�C•–O�7 UIV–O C–O�. In these charge-separated resonance structures, the uranium center isoxidized to uranium(IV) and the CO2 ligand reduced by one electron.
Carbon dioxide has been implicated as a maincontributor to global warming because of itsrole in radiative forcing (1). However, CO2
also represents an abundant renewable re-source for the production of fine chemicalsand clean fuels. Interest in metal-mediatedmultielectron reduction of CO2 therefore re-mains high, but the molecule’s inherent ther-modynamic stability hinders the developmentof metal catalysts that achieve CO2 activationand functionalization.
Particularly intriguing for synthetic chem-ists is the discovery of relatively simple coor-dination complexes that bind CO2 and facilitateits reduction (2). Chemists have isolated andstructurally characterized several synthetic met-al complexes of CO2, such as Aresta’s arche-typal [(Cy3P)2Ni(CO2)] (Cy � cyclohexyl) (3,4) and Herskowitz’s [(diars)2M(CO2)(Cl)][diars � o-phenylenebis(dimethylarsine); M �Ir, Rh] (5), featuring the bidentate �2-COO andcarbon-bound �1-CO2 binding modes, respec-tively. Activation of CO2 via its adsorption onmetal surfaces is of considerable interest forcatalysis at the gas-surface interface (6, 7).Most recently, Andrews and co-workers stud-ied the interaction of CO2 with a variety oftransition (8) and actinide (9) metal atoms gen-
erated via laser ablation. Although C–O bondcleavage of a proposed intermediate �2-COOcomplex is predominant in these surface-adsorbed systems, there also is spectral evi-dence for �1-OCO adsorption in low-tempera-ture matrices (Scheme 1) (8). The most impor-tant CO2 activation process occurs naturallyduring photosynthesis. It was proposed thatduring photosynthetic CO2 fixation, an oxygen-coordinated CO2 ligand (�1-OCO) is enzymat-ically reduced by ribulose-1,5-bisphosphatecarboxylase-oxygenase (RuBisCO) (10). Oxy-gen coordination appears to be an indispensablestep for C-functionalization in this system. Re-cently, the relevance of the �1-OCO coordina-tion mode for biological systems was fueled bya crystallographic study on a deacetoxycepha-losporin C synthase (DAOCS) mutant. Thepresence of electron density in proximity to theactive site’s iron center was found to be con-sistent with a monodentate O-bound CO2 mol-ecule (11). However, definitive structural char-acterization of inorganic coordination complex-es with a linear oxygen-bound �1-OCO coor-dination mode has remained elusive (2).
Department of Chemistry and Biochemistry, Univer-sity of California, San Diego, 9500 Gilman Drive, MC0358, La Jolla, CA 92093, USA.
*To whom correspondence should be addressed. E-mail: [email protected] Scheme 1.
R E P O R T S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1757
The large negative reduction potential andoxophilicity of trivalent uranium complexescan be applied to CO2 fixation. Coordinationcomplexes of uranium have undergone a re-naissance in the past few years (12). It hasbeen shown that, if stabilized by a suitablesupporting ligand set, uranium compoundsare highly reactive (13) and can engage in theformation of carbon monoxide (14, 15),dinitrogen (16, 17), and even alkane com-plexes through f -orbital interaction (18).
Here, we report carbon dioxide coordi-nation by a uranium compound resulting inreductive activation of the CO2 ligand. Forthe exploration of CO2 coordination andredox chemistry with a reactive uraniumcenter, we sought to use the electron-richuranium(III) complex [((AdArO)3tacn)UIII][1, (AdArOH)3tacn � 1,4,7-tris(3-adaman-tyl-5-tert-butyl-2-hydroxybenzyl)1,4,7-triazacyclononane] (19).
The uranium center of coordinatively un-saturated 1 is located deep inside a cavityformed by the hexadentate aryloxide-func-tionalized polyamine chelator. Intramolecularhydrophobic interactions between the hydro-carbyl substituents displace the U ion belowthe trigonal plane of the three aryloxideligands. The sterically demanding adamantylgroups form a narrow cylindrical cavityabove the uranium ion, thereby providingrestricted access to an incoming ligand andprotecting the uranium center from bimolec-ular decomposition reactions.
Exposure of toluene solutions or even solidsamples of intensely colored 1 to CO2 gas (1atm) results in instantaneous discoloration of thesamples (20). After filtration and concentrationof the toluene reaction mixture, colorless crystalsof [((AdArO)3tacn)UIV(CO2)] (2) are isolated in�50% yield (Scheme 2). The infrared spectrumof the crystalline sample in Nujol clearly exhibitsa distinct vibrational band centered at 2188cm�1, indicative of a coordinated and signifi-cantly activated CO2 ligand. When 1 is exposedto isotopically labeled 13CO2 gas, this band shiftsto 2128 cm�1 (fig. S1). The 12C/13C isotopicratio R (2188/2128) of 1.0282 is close to thatof free CO2 gas (R � 1.0284), indicative of amolecule that has the linear geometry of freeCO2 as well as the same carbon motion,�3(�asOCO), in this vibrational mode.
An x-ray diffraction analysis of single crys-tals obtained from a mixture of methylene chlo-ride and diethyl ether confirms the presenceof a coordinated carbon dioxide ligand(21). Unexpectedly, the CO2 ligand in[((AdArO)3tacn)UIV(CO2)] � 2.5 Et2O (2 � 2.5Et2O) is coordinated to the uranium ion in alinear, oxygen-bound �1-OCO fashion (Fig. 1).This CO2 coordination mode likely is enforcedby the adamantyl substituents of the supportingligand platform. The U�OCO group has a U�Obond length of 2.351(3) Å (here and below,values in parentheses are errors in the last sig-
nificant digit); the neighboring C–O bond lengthis 1.122(4) Å; and the terminal C�O bondlength is 1.277(4) Å. The U�O�C andO�C�O angles of 171.1(2)° and 178.0(3)°, re-spectively, are close to linear. These metric pa-rameters, together with the frequency redshift ofthe vibrational bands (�3:�O
12CO � 2188 cm�1,
�O13
CO � 2128 cm�1), strongly suggest a mo-lecular structure with charge-separated reso-nance structures UIV�O�C•–O� 7 UIV–O C–O�. Such an electronic structure wouldresult from a metal-centered one-electron oxida-tion upon CO2 coordination.
This bonding assignment is further supportedby comparison of complex 2 with a structurallysimilar azido complex (Fig. 2). Uranium(III) com-plex 1 reacts with one-electron oxidizers, such astrimethylsilyl azide (22), benzyl chloride, benzylbromide, and iodine to form the respective seven-coordinate halide and pseudohalide UIV complex-es [((AdArO)3tacn)UIV( X)] [X � N3 (3), Cl, Br,I] (20). The azido ligand, which typically adopts abent orientation at metal centers, is linearly coor-dinated in complex 3 [�(U�N��N�) �175.6(3)°, �(N��N��N�) � 177.2(5)°,d (U�N�) � 2.372(3) Å, d (N��N�) � 1.128(4)Å, d (N��N�) � 1.147(5) Å] (21). As with theCO2 coordination mode in 2, this bondingmotif is most likely imposed by the stericallyencumbering substituents. The azido ligand
allows estimation of the cavity depth of thesupporting ligand framework, which is ap-proximately equal to the sum of the d (U�N)and d (N�N) bond distances (4.65 Å).
Comparison of the CO2 and azido complexes2 and 3 with the starting compound 1 reveals thatafter axial ligand coordination, the central urani-um ion is situated closer to the trigonal planararyloxide ligand environment. Whereas the ura-nium(III) ion in 1 is located 0.88 Å below theligand plane, the uranium center in 2 and 3 isdisplaced only 0.274 Å and 0.291 Å below theplane, respectively. The average U�Ntacn andU�OArO distances in 3 were determined to be2.659(3) and 2.155(2) Å and thus are almostidentical to those found in 2 [2.673(2) and2.157(2) Å]. The U�OArO bond distances in 2and 3 are significantly shorter than those foundin the parent trivalent complex 1 [2.226(9) Å], aswell as UIII complexes of the related(t-BuArO)tacn ligand system (23), namely[((t-BuArO)3tacn)UIII(CH3CN)] [2.265(5) Å](22) and [((t-BuArO)3tacn)UIII(MeCy-C6)][2.244(3) Å] (18). Given the assignment of thevalence in 3 as UIV with an N3
– azido ligand andthe structural similarities of complexes 2 and 3,the oxidation state for the uranium center in 2 isalso assigned as UIV with a CO2
� ligand.The electronic structure of 2 was examined
by comparison of superconducting quantum in-
Fig. 1. ORTEP (OakRidge thermal ellipsoidplot) of uranium CO2complex 2 and in crys-tals of 2 � 2.5 Et2O (topleft) with core structureand metric parametersin angstroms and de-grees (top right) andspace-filling representa-tions (bottom). Urani-um, magenta; nitrogen,blue; oxygen, red; car-bon, gray.
Scheme 2. Synthesis of complexes.
R E P O R T S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1758
terference device (SQUID) magnetization dataand electronic absorption spectra of 1, 2, and 3(20). Over the temperature range 5 to 300 K,solid samples of 2 display a distinctly tempera-ture-dependent magnetic moment (Fig. 3).
The magnetic moment eff of 2 was deter-mined to be 2.89 B (where B is in units ofBohr magnetons) at 300 K; it slowly decreaseswith decreasing temperatures, reaching a valueof 2.6 B at 100 K. Below 100 K, eff decreasesrapidly, reaching a value of 1.51 B at 5 K.Between 300 K and 75 K, the temperature de-pendence of the eff value of 2 shows a curvaturereminiscent of data obtained for the UIV complex3. Although the room-temperature eff value of 2is close to that found for the azide complex 3, thelow-temperature value is similar to that of theUIII ( f 3) starting material 1 (1.73 B at 5 K),which has a doublet ground state at low temper-atures (19). Generally, UIV complexes with an f 2
(3H4) electron configuration have a singletground state that exhibits temperature-indepen-dent paramagnetism at very low temperatures,resulting in eff values of �0.5 B like that of 3(fig. S2) (20). The CO2 complex 2, however, hasa significantly greater eff value at low temper-ature, which reinforces the description of the
CO2 ligand as one-electron reduced CO2•� rad-
ical anion coordinated to a UIV ion. The transferredcharge (virtually one unpaired electron) is localizedon the coordinating CO2 ligand. In contrast to theclosed-shell N3
� ligand of 3, the open-shell CO2•�
likely contributes to the observed increase in eff
value of 2 at low temperatures.To further probe the formal oxidation
state of the uranium ion, we recorded theultraviolet/visible/near-infrared (NIR) elec-tronic absorption spectrum of 2 and com-pared it to spectra of known UIII and UIV
complexes (figs. S3 and S4) (20). Mostnotably, although UIII and UV complexes ofthe (ArO)3tacn ligand are deeply colored(22), UIV complexes of this ligand system,as well as the uranium-CO2 complex 2,appear colorless to very pale blue-green insolution and in the solid state (22, 23). Theabsorption spectra of deep red uranium(III)complexes of the ((ArO)3tacn)U system,such as 1, are dominated by an intenseabsorption band centered at 455 nm (ε �1945 M�1 cm�1) (20), which can be as-signed to either an allowed d�f ligandfield or ligand-to-metal charge-transfertransition. In addition, f �f transitions give
rise to a number of weak absorption bandsin the NIR region between 800 and 2200nm (ε � 50 to 150 M�1 cm�1). In con-trast, the colorless uranium(IV) com-plexes [((ArO)3tacn)U(CO2)] (2) and[((ArO)3tacn)U(N3)] (3) exhibit weak ab-sorption bands over the entire visible andNIR region (20). The band intensities andpositions are characteristic of the UIV f 2 ion(24). Taken together, the metrical and spec-troscopic data thus support a one-electrontransfer from U to CO2 in formation of thislinearly bound, O-coordinated complex.
References and Notes1. P. Falkowski et al., Science 290, 291 (2000).2. D. H. Gibson, Chem. Rev. 96, 2063 (1996).3. M. Aresta, C. F. Nobile, V. G. Albano, E. Forni, M.Manassero, J. Chem. Soc. Chem. Commun. 1975, 636(1975).
4. M. Aresta, C. F. Nobile, J. Chem. Soc. Dalton Trans.1977, 708 (1977).
5. T. Herskovitz, J. Am. Chem. Soc. 99, 2391 (1977).6. H. J. Freund, R. P. Messmer, Surf. Sci. 172, 1 (1986).7. D. H. Gibson, Coord. Chem. Rev. 185–186, 335 (1999).8. P. F. Souter, L. Andrews, J. Am. Chem. Soc. 119, 7350
(1997).9. L. Andrews, M. F. Zhou, B. Y. Liang, J. Li, B. E. Bursten,
J. Am. Chem. Soc. 122, 11440 (2000).10. H. Mauser, W. A. King, J. E. Gready, T. J. Andrews,
J. Am. Chem. Soc. 123, 10821 (2001).11. H. J. Lee et al., J. Mol. Biol. 308, 937 (2001).12. D. L. Clark, A. P. Sattelberger, R. A. Andersen, Inorg.
Synth. 31, 307 (1997).13. P. L. Diaconescu, P. L. Arnold, T. A. Baker, D. J.Mindiola, C. C.
Cummins, J. Am. Chem. Soc. 122, 6108 (2000).14. J. G. Brennan, R. A. Andersen, J. L. Robbins, J. Am.
Chem. Soc. 108, 335 (1986).15. M. delMar Conejo et al., Chem. Eur. J. 5, 3000 (1999).16. P. Roussel, P. Scott, J. Am. Chem. Soc. 120, 1070 (1998).17. A. L. Odom, P. L. Arnold, C. C. Cummins, J. Am. Chem.
Soc. 120, 5836 (1998).18. I. Castro-Rodriguez et al., J. Am. Chem. Soc. 125,
15734 (2003).19. H. Nakai, X. Hu, L. N. Zakharov, A. L. Rheingold, K.Meyer, Inorg. Chem. 43, 855 (2004).
20. See supporting material on Science Online.21. Data collections were performed at 100(2) K on a Bruker
SMART APEX diffractometer with a charge-coupled device(CCD) area detector, with graphite-monochromated MoK� radiation (� � 0.71073 Å). Molecular structures weresolved by direct methods and refined on F2 by full-matrixleast-squares techniques. For 2 � 2.5 Et2O: monoclinic,P21/n, a � 16.0494(12) Å, b � 21.0575(16) Å, c �22.2629(17) Å, � � 93.3720(10), V� 7510.9(10) Å3, Z �4, R � 0.0326, wR2 � 0.0772. For 3 � 3 CH2Cl2: ortho-rhombic, P212121, a� 10.7294(6) Å, b� 23.0272(13) Å,c � 28.5498(17) Å, V� 7053.7(7) Å3, Z � 4, R� 0.0529,wR2 � 0.1191.
22. I. Castro-Rodriguez, K. Olsen, P. Gantzel, K. Meyer,J. Am. Chem. Soc. 125, 4565 (2003).
23. I. Castro-Rodriguez, K. Olsen, P. Gantzel, K. Meyer,Chem. Commun. 2002, 2764 (2002).
24. J. J. Katz, L. R. Morss, G. T. Seaborg, The Chemistry of theActinide Elements (Chapman & Hall, New York, 1980).
25. Supported by the University of California, San Diego,and U.S. Department of Energy grant DE-FG02-04ER15537. We thank W. L. S. Andrews and N.Edelstein for insightful discussions and NIH for afellowship to I.C.R. (3 T32 DK07233-2651). K.M. is anAlfred P. Sloan fellow. Crystallographic data weredeposited in the Cambridge Crystallographic Data-base Centre (2: CCDC-244303; 3: CCDC-244304).
Supporting Online Materialwww.sciencemag.org/cgi/content/full/305/5691/1757/DC1Materials and MethodsSOM TextFigs. S1 to S4
9 July 2004; accepted 13 August 2004
Fig. 2. Molecular struc-ture of precursor com-plex 1 in crystals of 1 �C6H14 (top left) andazido complex 3 in crys-tals of 3 � 3 CH2Cl2 (topright) and respectivespace-filling representa-tions (bottom).
Fig. 3. Temperature-dependent SQUIDmagnetization data for trivalent 1 (�),uranium CO2 complex 2 (●), and tetrava-lent azido complex 3 (}) measured in thetemperature range 5 to 300 K at 1 T.
R E P O R T S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1759
Age and Timing of the PermianMass Extinctions: U/Pb Dating of
Closed-System ZirconsRoland Mundil,1* Kenneth R. Ludwig,1 Ian Metcalfe,2
Paul R. Renne1,3
The age and timing of the Permian-Triassic mass extinction have been difficultto determine because zircon populations from the type sections are typicallyaffected by pervasive lead loss and contamination by indistinguishable olderxenocrysts. Zircons from nine ash beds within the Shangsi andMeishan sections(China), pretreated by annealing followed by partial attack with hydrofluoricacid, result in suites of consistent and concordant uranium/lead (U/Pb) ages,eliminating the effects of lead loss. The U/Pb age of the main pulse of theextinction is 252.6 � 0.2 million years, synchronous with the Siberian floodvolcanism, and it occurred within the quoted uncertainty.
Despite intensive study, the cause and timingof events associated with the Permian-Trias-sic (P-T) extinction—the most profound suchextinction known over the history of life onEarth—remain uncertain. Most scenariosproposed in the past few years have invokeda catastrophic event, which almost by defini-tion requires unusually precise geochronol-ogy for a meaningful test. Geochronology onthe volcanic deposits intercalated with thesediments at the Global Stratotype Sectionand Point (GSSP) section in Meishan is dif-ficult using the U/Pb method on zircon (1)—the most accurate available method and theonly suitable mineral for U/Pb isotopic datingin these ashes. Zircon populations from thesebeds are typically contaminated with slightlyolder xenocrysts indistinguishable in appear-ance and corrupted by variable amounts ofpostdepositional Pb loss. Age lowering fromthe latter is pervasive (2) even when thesurfaces of the crystals are removed by airabrasion (2, 3). A previous U/Pb-zircon study(4), using analyses of both single- and mul-ticrystal samples of air-abraded zircons, aswell as subsequent research on extinctionpatterns (5) and using the ages in (4), pro-posed (i) an age of 251.4 � 0.3 million years(Ma) for the main pulse of the extinction (5),(ii) a duration of no more than 0.165 Ma(from the sedimentation rate implied by thebracketing ages) for the carbon isotope(�13C) excursion, and (iii) an age of 251 Mafor the P-T boundary (base Triassic) definedby the First Appearance Datum (FAD) of theconodont Hindeodus parvus (at the GSSPsection in Meishan, eastern China). This dataset was complex (such that most of the data
were excluded from consideration). Recenttime-scale compilations and most subsequentstudies regarding causes and rates of the bi-otic crisis have adopted these ages. A subse-quent study (1) on samples from the same ashbeds but analyzing single zircons concludedthat reliable U/Pb ages with such low uncer-tainties are difficult to obtain from such com-plex zircon populations, and suggested thatthe age of the base of the Triassic is�252.5 � 0.3 Ma (on the basis of an age foran ash layer postdating the P-T boundary).The maximum age of the mass extinction wasplaced at 254 Ma [which was acknowledgedto be “a weak conclusion” (1) on the basis ofan incoherent data set from an ash bed at themass extinction level]. Here we present a newanalysis of single zircons from the type sec-tions in which the pretreatment pioneered in(6, 7) removes the problems of lead loss andyields coherent data sets for all of the ana-lyzed ash layers.
Most of our samples are from the Shangsisite (32°20N, 105°28E, north Sichuan Prov-ince, central China). The late Permian–earlyTriassic sedimentary rocks are exposed in aroad cut and in a parallel section in a riverbed(fig. S1C). Upper Permian limestones gradeinto fine-grained lowermost Triassic sand-stone. As at Meishan (Zhejiang province,southeast China), volcanic ash beds are inter-calated within the sediments. The successionis correlated in detail with the GSSP sectionin Meishan (8–10). The extinction horizoncoincides with the base of bed 28 [bed num-bers are according to (8)], just postdating ashhorizon SH10(27) [bed numbers for all ashsamples according to (8) are given in paren-theses]. The first appearance of H. parvus isfound in bed 30 at the 104.6-m level where itoccurs together with Isarcicella turgida. Thelatter is regarded as the descendent of H.parvus, and this indicates that the true P-Tboundary level (equating to the first appear-
ance of H. parvus in the GSSP section atMeishan) may be some short distance belowthe 104.6-m level at Shangsi. The �13Crecord at Shangsi, although based on sparsersampling, shows a minimum of � �5‰, asignificantly lower value than at Meishan (5).One study placed the �13C minimum (11) atShangsi 5 m above the mass extinction hori-zon, whereas another (12) placed it with theextinction (within bed 28).
In general, the commonly used techniquesfor eliminating regions of zircons that haveexperienced Pb loss (e.g., air abrasion, leach-ing by hot HF at 1 atm.) are only moderatelysuccessful (1, 3, 13). However, application ofa pretreatment method (6, 7) involving high-temperature annealing, followed by partialHF digestion at high temperature and pres-sure, can be effective at removing portions ofzircons that have lost Pb, without affectingthe isotopic systematics of the remaining ma-terial. The aggressiveness of the techniquenaturally evokes concerns of laboratory arti-facts in the resulting analyses. However, dif-fusion of Pb out of the zircons during theannealing step is ruled out by the studies of(14, 15), as well as by the striking statisticalcoherence of the resulting U/Pb ages. Scan-ning electron microscopy (SEM) images(Fig. 1) of annealed and “chemically abrad-ed” (7) zircon crystals show that domainsaffected by Pb loss are specifically removedduring the partial HF-attack phase. Unlike airabrasion, this approach seems to access suchdomains well into the crystal interior.
We analyzed zircons from eight volcanic-ash layers of Late Permian age in the marinesuccession of Shangsi (north Sichuan, China)and also from the boundary clay [bed 25 in (9),sample D3t in this study] from the GSSP sec-tion in Meishan (Zhejiang, China). Unless oth-erwise stated, all ages reported here are weight-ed-mean 206Pb/238U ages [uncertainties are giv-en at 2� or 95% confidence (Fig. 2 and tableS1); see (2) for analytical procedures].
Six zircons from sample SH01(7), from alower Wuchiapingian ash horizon at 23.5 m,yield an age of 259.1 � 1.0 Ma. Zircons fromthe lower Wuchiapingian ash layer SH03(8)(36.3 m) are small and low in U, so that, likeSH01(7), uncertainties for individual analy-ses are relatively large. Isotopic data from allfive analyzed zircon crystals define a coher-ent cluster, with an age of 260.8 � 0.8 Ma.Analysis of the leachate from the combinedzircons indicates that the chemically abradedportions of the crystals had lost an average of8% of their radiogenic Pb. The weighted-mean 206Pb/238U ages of SH01(7) andSH03(8) are not in stratigraphic order. Al-though the error ellipses of both analysesoverlap concordia, the centroid of theSH01(7) ellipse falls to the left of concordia,SH03(8) to the right. As a result, the most-probable age of SH01(7) is slightly older than
1Berkeley Geochronology Center, 2455 Ridge Road,Berkeley, CA 94709, USA. 2Asia Centre, University ofNew England, Armidale NSW 2351, Australia. 3De-partment of Earth and Planetary Science, Universityof California, Berkeley, CA 94720, USA.
R E P O R T S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1760
the 206Pb/238U age, and that of SH03(8) isslightly younger. The concordia age algo-rithm (16), which makes use of all of theU/Pb isotopic ratios, errors, and error corre-lations at once, provides the best tool forevaluation of the SH01(7)-SH03(8) data. Theconcordia ages of SH01(7) and SH03(8) are259.5 � 0.9 Ma and 260.4 � 0.8 Ma, respec-tively, indicating that an apparent reversal ofage-order for the two samples is not particu-larly improbable [and can be used as a Bayes-ian constraint—see later discussion—to inferthat SH01(7) is 0.06�0.06
�0.81 Ma older thanSH03(8)].
Eight analyses of single zircons from vol-canic-ash layer SH08(15) [upper Wuchiap-ingian (8)] at the 72.5-m level yield a tightcluster of analyses with an age of 257.3 � 0.3Ma. These zircons also are low in U, but withmuch larger crystal size (hence lower errors)than those from SH03(8).
Thirty-four zircons from ash layerSH16(18) (upper Wuchiapingian) were sub-jected to a variety of pretreatments (Fig. 1).More than half of the zircons pretreated witheither air abrasion (3, 4) or mild HF leachingalone (1) yield scattered and younger agesindicative of Pb loss. The median U concen-tration of untreated zircons and of those sub-jected to air abrasion and mild HF leaching issignificantly higher than those of annealed/chemically abraded crystals, which indicatesthat zones high in U are preferentially re-moved by the latter pretreatment. All six ofthe analyzed leachates from individual an-nealed and chemically abraded zircons fromSH16(18) have younger ages, implying do-mains with 12 to 42% Pb loss (Fig. 1).
Of the 16 annealed and chemically abradedzircons, two are slightly but resolvably olderand were excluded from the mean because we
assumed that they either represent xenocrysts orharbor inherited components. We so excludedonly 3 of the 79 concordant analyses of thisstudy, and none of these were from the young(Pb loss) side of the distributions. The remain-ing 14 analyses form a coherent cluster andyield an age of 253.7 � 0.2 Ma.
Eight zircons from sample SH27(23)(97.1-m level), less than 3 m below the ex-tinction horizon, yield an age of 253.2 � 0.3Ma. One crystal was slightly but resolvablyolder than the other eight and was rejected asabove. Another crystal appears marginallyolder than the main cluster, but its inclusionwith the main group does not lower the prob-ability of fit (0.15) to an unacceptable level,and in any case has a negligible effect on theweighted-mean age and uncertainty. Sevenother analyses have 207Pb/206Pb ages be-tween 860 and 2700 Ma and thus indicate thepresence of significantly older inherited zir-con, almost certainly as cores.
All analyses from 12 zircons from sampleSH09(25) (99.7-m level, about 0.3 m belowthe extinction horizon) cluster within analyt-ical error and define an age of 252.5 � 0.3Ma. All five zircon analyses from ash bedSH10(27) (100.05-m level), which underliesthe extinction horizon, form a coherent clus-ter with an age of 252.2 � 0.4 Ma—indistin-guishable from that of SH09(25).
Sample SH32(29) is from an ash layer atthe 103.4-m level, 1.1 m below the first ap-pearance of H. parvus but most likely withinthe lowermost Triassic (see above). One ofthe 13 analyzed zircons from SH32(29) con-tains an inherited component (207Pb/206Pbage � 890 Ma). The remaining 12 yield anage of 252.5 � 0.2 Ma. Although the crystalwith the youngest age of these 12 appears justdistinguishable from the other 11, the weight-
B
0.026
0.034
0.20 0.30
abraded
HF leached
untreated
160
200
240
206 P
b/23
8 U
207Pb/235U
annealed/"chemically abraded"
leachates
abra
ded
HF
leac
hed
untr
eate
d
20µ
m
Different approachesaimed at minimizing Pb lossSH16
A
annealed (850°C, 36 hrs)
age
(Ma)
leac
hate
s
hp leached (HF@220°C, 16 hrs)
260
Fig. 1. Concordia diagram (A) and ranked ages (B) of zircon analyses from sample SH16(18)obtained from different approaches aimed at minimizing the effects of Pb loss. SEM image of azircon shows the effects of chemical abrasion following annealing (uncertainties are given at the95% confidence level).
248
252
256
260
264
248
252
256
260
264
248
252
256
260
264
248
252
256
260
264
248
252
256
260
264
248
252
256
260
264
248
252
256
260
264
252
256
260
264
0.24 0.28 0.32207Pb/235U
264
260
256
252
248
264
260
256
252
248
264
260
256
252
248
264
260
256
252
248
264
260
256
252
248
264
260
256
252
248
264
260
256
252
248
0.039
0.040
0.041
0.039
0.040
0.041
0.039
0.040
0.041
0.039
0.040
0.041
0.039
0.040
0.041
0.039
0.040
0.041
0.039
0.040
0.041
SH08(15)
SH16(18)
SH27(23)
SH09(25)
SH10(27)
SH32(29)
D3t-bed 25
precision
257.3 ± 0.3 MaMSWD = 0.6
253.7 ± 0.2 MaMSWD = 1.0
253.2 ± 0.3 MaMSWD = 1.1
252.5 ± 0.3 MaMSWD = 1.6
252.2 ± 0.4 MaMSWD = 1.1
252.5 ± 0.2 MaMSWD = 0.8
252.4 ± 0.3 MaMSWD = 0.5
age
(Ma)
Meishan
Shangsi
260
concordia age
SH01(7)/SH03(8)
206 P
b/23
8 U
259.1 ± 1.0 MaMSWD = 0.3
260.8 ± 0.8 MaMSWD = 0.8
Fig. 2. Concordia diagrams (left) and individ-ual 206Pb/238U ages (ranked by their uncer-tainties) of zircon analyses from volcanic-ashlayers from Shangsi [sorted by stratigraphicage from oldest (bottom) to youngest (top)]and Meishan. SH01(7) and SH03(8) (gray) arecombined, showing the overlap of the x-yweighted mean of the single-zircon analysesfor each sample (thick outline).
R E P O R T S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1761
ed-mean age and error are almost identical,whether or not the suspect analysis is includ-ed. The leachate of the combined sampleshows that the leached parts have lost anaverage of 20% of their radiogenic Pb.
For comparison with the Shangsi ages, sixzircons were analyzed from sample D3t (1)from the GSSP section in Meishan (bed 25,overlying the extinction horizon). The analysesare coherent, with an age of 252.4 � 0.3 Ma—indistinguishable from the age of SH10(27), aswell as SH09(25) and SH32(29). The strati-graphic order of the Shangsi ash horizons canbe used to refine the ages and errors one more
step. The methodology for doing so involvesthe use of Bayesian statistics and is like thatapplied to suites of radiocarbon ages (17–19).Prerequisites of the method for zircon geochro-nology are that (i) sufficient statistically coher-ent single-crystal replicate analyses exist to val-idate the assumption of a unimodal age-popu-lation, and (ii) there is little or no data culling,so that the assigned age-errors are both realisticand Gaussian.
For our purposes, the most useful appli-cation is to determine the differences in agesbetween beds whose ages are otherwise un-resolvable [thus circumventing the problemof the “push-apart” effect on the ages them-selves (20, 21)]. Using the SH27(23),SH09(25), SH10(27), and SH32(29) ages andstratigraphic order and Isoplot 3 (22) to per-form the calculations, we find that the most-probable duration between SH09(25) andSH10(27) is less than 0.3 Ma. Similarly, theduration between SH10(27) and SH32(29) isfound to be less than 0.3 Ma (that is, 0.0�0.0
�0.3
Ma, 95% confidence), compared to the strati-graphically unconstrained estimate of�0.2 � 0.5 Ma. The bracketing ages of250.7 � 0.3 and 251.4 � 0.3 Ma used asconstraints for the age of the P-T boundaryand for the duration of the negative �13Cexcursion in (4) imply a time interval of nomore than 0.7 � 0.4 Ma, but these ages areunsuitable for such a calculation, in that theyare based on both multi- and single-crystalanalyses and excluded data.
Because we cannot detect complexities ata level much less than the precision of theindividual analyses (�3‰), we cannot re-solve the presence of pervasive Pb loss at the1‰ to 3‰ level, zircons from eruptions onlya few hundred thousand years earlier, or zir-cons with long magma-residence times. Suchconsiderations imply that the practical limitof the resolution of U/Pb zircon dating maynot be much better—perhaps a factor of2—than the precision of a single good anal-ysis, with unquantified magma-residencetime imposing another limit of perhaps asmuch as 0.3 Ma (23, 24).
From these new, unambiguous ages weconclude the following: (i) The biotic crisisoccurred at 252.6 Ma. The age of the bios-tratigraphic P-T boundary (FAD of H. parvusin Meishan) is slightly but unresolvablyyounger. This age is consistent with the pre-vious estimate for the age of bed AW3 atMeishan [bed 28 in (9)], 8 cm above the P-Tboundary (1), whereas the age of the extinc-tion is younger than our earlier, tentativeestimate (1). (ii) The tempo and duration ofthe main pulse of the P-T mass extinction arenot resolvable, even with age precisions at orbelow the per mil level. (iii) The interpolatedage of the Wuchiapingian-Changxingianboundary is 256 Ma [on the basis of third-order polynomial fit; a linear regression be-
tween SH08(15) and SH16(18) yields thesame result (Fig. 3)], younger than the esti-mate in (1). (iv) The inferred age for the baseof the Wuchiapingian stage and the endGuadalupian extinction is �260 Ma. (v) Thecarbon-isotope anomaly at Shangsi may havecommenced as much as 2 million years be-fore the P-T boundary, although the sparseavailable data leave this question open.
Several scenarios for the P-T extinctionhave been proposed and critically evaluated,including (i) a bolide impact (25–29), (ii)catastrophic environmental change caused bygiant-scale volcanism (30, 31), and (iii) meth-ane release (32, 33). Geochronology (40Ar/39Ar) applied to a purported impact brecciainterpreted to be of P-T boundary age (27)shows unambiguous evidence of disturbanceand, even if such evidence is ignored, is onlyconstrained within a 20-million-year interval.The end of the Permian Period is character-ized by an abundance of short and volumi-nous pulses of continental flood basalts, andthe timing of the volcanism appears to beindistinguishable from that of the mass ex-tinctions at the end of the Middle Permian(end Guadalupian, Emeishan basalt) and theend of the Permian [Siberian flood basalt (30,31)]. Synchrony between the end Guadalu-pian extinction (34) and the Emeishan igne-ous province is loosely constrained by a U/Pbsensitive high-resolution ion microprobe(SHRIMP) age of 259 � 3 Ma for the Xinjieintrusion (35) and the estimate of �260 Mafor the base of the Wuchiapingian presentedhere, although tighter constraints are needed.The synchrony of Siberian flood volcanismwith the P-T mass extinction has been dem-onstrated by indistinguishable 40Ar/39Ar agesof 250 Ma for the main pulse of the volca-nism and for ash beds close to the extinctionlevel from Meishan and Shangsi (30). 40Ar/39Ar ages based on conventional calibrationsare systematically younger in the Paleozoicand Mesozoic by about 1% than U/Pb ages[most likely due to a miscalibration of the40K decay constants and data for standards(36)]. The 40Ar/39Ar age reported for Meis-han bed 25 (30) recalculates to 252.1 � 1.6Ma based on the standard and decay-constantcalibration suggested in (37), in agreementwith the U/Pb ages presented here. We thusconclude that (i) the Siberian volcanism andthe P-T extinction event are essentially syn-chronous (with the same scenario possiblyapplying to the Emeishan volcanism and theend Guadalupian extinction) and (ii) that theextinction occurred over a very short time.
References and Notes1. R. Mundil et al., Earth Planet. Sci. Lett. 187, 131
(2001).2. Analytical procedures are available as supporting ma-
terial on Science Online.3. T. E. Krogh, Geochim. Cosmochim. Acta 46, 637
(1982).
Wuc
hiap
ingi
anC
hang
ian
0
20
40
80
100
Wuc
hiap
ing
Fm
Dal
ong
Fm
Fei
xian
guan
Fm
Grie
sbac
hian
Tria
ssic
Per
mia
n
volc
anic
ash
es
δ13C (â )
31
18
16
15
14131211
10
9
7
6
5
3
2
SH01
SH03
SH08
252 256 260
extinction
FAD H. parvus
98
100
102
104
252 253 254
28
29
30
23
SH16
age (Ma)
(m a
bove
bed
4)
-5 0 5
extinction
FAD H. parvus
98
100
102
104
252 253
SH27SH09SH10
SH32
254
28
29
30
23
31
extinction
FAD H. parvus
98
100100
102
104
252 253
7SH27777SH09SH10
SH32
254
28
29
30
23 S
SH27
SH09
SH10
SH32
sedi
men
tatio
n ra
teof
10m
/1m
.y.
Fig. 3. Schematic diagram of the Shangsi sec-tion showing subdivision of stages, formationsand bed numbers (8), position of ash layers, andages versus stratigraphy including estimatedsedimentation rate (third-order polynomial fitthrough ages is obtained from a Bayesian ap-proach, not corrected for decompaction) aswell as �13C values [(11), blue and (12), red).The P-T transition is shown in detail in theenlargement.
R E P O R T S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1762
4. S. A. Bowring et al., Science 280, 1039 (1998).5. Y. G. Jin et al., Science 289, 432 (2000).6. J. M. Mattinson, paper presented at the American
Geophysical Union Meeting, San Francisco, 10 to 14December 2001.
7. J. M. Mattinson, in preparation.8. Z. Li et al., Dizhixue Bao [Acta Geol. Sin.] 60, 1 (1986).9. H. Yin, K. Zhang, J. Tong, Z. Yang, S.Wu, Episodes 24,
102 (2001).10. R. S. Nicoll, I.Metcalfe, C.Wang, J. Asian Earth Sci. 20,
609 (2002).11. A. Baud,M.Magaritz,W. T. Holser, Geol. Rundsch. 78,
649 (1989).12. W. C. Sweet, Y. Zunyi, J. M. Dickins, H. Yin, in Permo-
Triassic Events in the Eastern Tethys, W. C. Sweet, Y.Zunyi, J. M. Dickins, H. Yin, Eds. (Cambridge Univ.Press, Cambridge, 1992), pp. 1–8.
13. J. M. Mattinson, Contrib. Mineral. Petrol. 116, 117(1994).
14. D. J. Cherniak, E. B.Watson, Chem. Geol. 172, 5 (2000).15. J. K. W. Lee, I. S. Williams, D. J. Ellis, Nature 390, 159
(1997).16. K. R. Ludwig, Geochim. Cosmochim. Acta 62, 665 (1998).17. C. E. Buck, W. G. Cavanagh, C. D. Litton, BayesianApproach to Interpreting Archaeological Data (Wiley,Chichester, UK, 1996).
18. C. D. Litton, C. E. Buck, Archaeometry 37, 1 (1995).
19. C. B. Ramsey, Radiocarbon 40, 461 (1998).20. G. Nicholls, M. Jones, “Radiocarbon dating with tem-
poral order constraints,” Tech. Rep. No. 407 (Univ. ofAuckland, New Zealand, 1998).
21. C. Stein, paper presented at the 3rd Berkeley Sym-posium on Mathematical Statistics and Probability,Berkeley, December 1954, July–August 1955.
22. K. R. Ludwig, User’s Manual for Isoplot 3.00 (BerkeleyGeochronology Center, Berkeley, CA, 2003).
23. M. R. Reid, C. D. Coath, T. M. Harrison, K. D. McKee-gan, Earth Planet. Sci. Lett. 150, 27 (1997).
24. S. J. A. Brown, I. R. Fletcher, Geology 27, 1035 (1999).25. L. Becker, R. J. Poreda, A. G. Hunt, T. E. Bunch, M.
Rampino, Science 291, 1530 (2001).26. A. R. Basu, M. I. Petaev, R. J. Poreda, S. B. Jacobsen, L.
Becker, Science 302, 1388 (2003).27. L. Becker et al., Science 304, 1469 (2004).28. K. A. Farley, S. Mukhopadhyay, Science 293, U1
(2001).29. C. Koeberl, I. Gilmour, W. U. Reimold, P. Claeys, B. V.
Ivanov, Geology 30, 855 (2002).30. P. R. Renne, Z. Zhang, M. A. Richards, M. T. Black, A. R.
Basu, Science 269, 1413 (1995).31. V. E. Courtillot, P. R. Renne, C. R. Acad. Sci. Geosci.
335, 113 (2003).32. E. S. Krull, G. J. Retallack, Geol. Soc. Am. Bull. 112,
1459 (2000).
33. G. Ryskin, Geology 31, 741 (2003).34. S. M. Stanley, X. Yang, Science 266, 1340 (1994).35. M. Zhou et al., Earth Planet. Sci. Lett. 196, 113
(2002).36. K. Min, R. Mundil, P. R. Renne, K. R. Ludwig, Geochim.
Cosmochim. Acta 64, 73 (2000).37. J. Kwon, K. Min, P. J. Bickel, P. R. Renne, Math. Geol.
34, 457 (2002).38. This study was supported by the NSF (EAR-0125799),
the Australian Research Council, and the Ann andGordon Getty Foundation.We thank J. Mattinson forgenerously sharing his ideas; B. Nicoll and ZhihaoWang for help and support in the field; M. Cover, A.DeHollan, and G. Johnson for lab assistance; and J.Feinberg for SEM imaging. This work is dedicated tothe late Rudolf H. Steiger.
Supporting Online Materialwww.sciencemag.org/cgi/content/full/305/5691/1760/DC1Materials and MethodsFig. S1Table S1References
2 June 2004; accepted 6 August 2004
Molecular Cloud Origin for theOxygen Isotope Heterogeneity
in the Solar SystemHisayoshi Yurimoto1* and Kiyoshi Kuramoto2
Meteorites and their components have anomalous oxygen isotopic composi-tions characterized by large variations in 18O/16O and 17O/16O ratios. On thebasis of recent observations of star-forming regions and models of accretingprotoplanetary disks, we suggest that these variations may originate in a parentmolecular cloud by ultraviolet photodissociation processes. Materials withanomalous isotopic compositions were then transported into the solar nebulaby icy dust grains during the collapse of the cloud. The icy dust grains driftedtoward the Sun in the disk, and their subsequent evaporation resulted in the17O- and 18O-enrichment of the inner disk gas.
Oxygen is the most abundant element in thesolid phases that formed early in the solarsystem, and it has three stable isotopes ofmass numbers 16, 17, and 18. On a three-oxygen isotope diagram, 18O/16O and 17O/16O abundance ratios of most terrestrial ma-terial constitute a line with slope of �0.5,called the terrestrial fractionation (TF) line.This slope is due to isotope fractionationprocesses that depend on the mass differencebetween each pair of isotopes. In contrast,most meteorites have oxygen isotopic com-positions that diverge from the TF line (1).Refractory inclusions and some chondrules inprimitive meteorites have the most 16O-en-riched isotope compositions, shifted from the
TF line with magnitudes of several percent in17O/16O and 18O/16O ratios (1, 2). Nonradio-genic effects in the other major elements(e.g., Mg and Si) in these meteorite constitu-ents have isotope compositions close to theterrestrial compositions, and their small devi-ations can be explained by isotope fraction-ation due to thermal processes, e.g., evapora-tion, condensation, aqueous alteration, andlow-temperature chemical reaction (3).
The origin of mass-independent fraction-ation of oxygen isotopes and the lack of suchfractionation in other major elements in me-teorites remains poorly understood. It cannotbe due to nucleosynthetic processes or nucle-ar reactions that involve energetic particlesfrom the Sun or from Galactic cosmic rays,because these processes would also changethe isotopic compositions of the other ele-ments (1). In addition, presolar grains en-riched in 16O are rare in meteorites (4). Al-though some types of molecular reactions ingaseous phases have been found to induce
such mass-independent isotope fractionationin oxygen (5), they are observed among gasspecies (e.g., O3, O2, and CO2) that are minorin the solar nebula (6). Furthermore, even ifsuch fractionation occurs, no plausible mech-anism has been proposed for trapping thefractionated products into chondrite constitu-ents. Oxygen isotope changes due to selectiveultraviolet (UV) dissociation of molecules inthe solar nebula gas have been proposed (5, 7,8); however, a mechanism for transferringthese effects to the chondritic constituents hasnot been identified.
Recently, variations in C16O/C18O ratiohave been observed in diffuse molecularclouds (9, 10). These variations are explainedby selective predissociation (11) of C18O byUV radiation. In the environment of molecu-lar clouds, predissociation due to line spec-trum absorption of UV photons is the domi-nant mechanism for photodissociation of CO(12–17). UV intensity at the wavelengths ofdissociation lines for abundant C16O rapidlyattenuates in the surface layer of a molecularcloud, because of its UV self-shielding. Forless abundant C17O and C18O, which haveshifted absorption lines because of differenc-es in vibrational-rotational energy levels, theattenuation is much slower. As a result, C17Oand C18O are dissociated by UV photonseven in a deep molecular cloud interior. Thisprocess results in selective enrichment of COin 16O and enrichment of atomic oxygen in17O and 18O.
Because CO and atomic oxygen are thedominant oxygen-bearing gas species in molec-ular clouds (18), their isotopic fractionationmay propagate to other oxygen-bearing species.Water ice is the dominant oxygen-bearing spe-cies among ices in molecular clouds (19),where it nucleates and grows on silicate dustgrains by surface hydrogenation reactions be-
1Department of Earth and Planetary Sciences, TokyoInstitute of Technology, Meguro, Tokyo 152–8551, Ja-pan. 2Division of Earth and Planetary Sciences, HokkaidoUniversity, Sapporo, Hokkaido 060–0810, Japan.
*To whom correspondence should be addressed. E-mail: [email protected]
R E P O R T S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1763
tween atomic oxygen and hydrogen (20, 21).Therefore, oxygen isotopic compositions ofH2O ice should be close to those of gaseousatomic oxygen enriched in 17O and 18O (22).Water ice is observed in molecular clouds withtotal visual extinction (AV) greater than 3.2(23); abundance of water ice increases withincreasing AV (24). As a molecular cloud be-comes dense, most of the atomic oxygen reactsto form H2O ice, and CO becomes the mostdominant gas species within 105 years (25).Thus, the oxygen isotopic composition of thegas in a dense molecular cloud becomes en-riched in 16O with time.
Low-mass (less than two solar masses) starsform by collapse of individual cores or clumps ina cold, dark molecular cloud with moleculardensities of hydrogen (nH2) of 104 to 105 cm�3,AV of 5 to 25, and temperatures as low as �10 K(26). According to a model simulating photo-chemical isotope fractionation in a molecularcloud (17), under these typical cloud parameters,the isotopic compositions of ice and gas areexpected to be in the ranges �18OMC � �100 to�250 per mil (‰) and �18OMC � –60 to–400‰, respectively, where �18OMC {[(18O/16O)/(18O/16O)MC] – 1} � 1000; (18O/16O) and(18O/16O)MC are the isotopic ratios of corre-sponding chemical species and the bulk molec-ular cloud (MC), respectively. The degrees offractionation for calculated 18O/16O ratios areconsistent with astronomical observations (9,10). Although the lack of experimental data forC17O predissociation prevents us from a detailedanalysis of 17O/16O fractionation, its degree islikely near that for 18O/16O, because the absorp-tion lines of these minor isotope species areunsaturated at least over several tens of AV (15,16). Such expected similarity has been recentlyobserved for diffuse interstellar gas (27).
In denser and more evolved cold molecu-lar cloud cores, most CO may become frozenonto dust grains. Because of the low temper-ature, oxygen isotope exchange between COand H2O ices is inefficient, and the originalisotope fractionation of oxygen is preservedin each phase. Transient external heating byshock waves or by other mechanisms wouldcause vaporization of both H2O and CO icesand local homogenization in such a cloud.However, as long as H2O and CO moleculesdo not decompose into radicals and atoms,the oxygen isotope fractionation in each mol-ecule is probably preserved.
Here we examine how such isotopic het-erogeneity in a molecular cloud may causethe variations of oxygen isotopic composi-tions observed in our solar system. Takingrelative oxygen abundances of silicates, ice,and gas to be 1:2:3 in molecular clouds (20),we assumed that both �17OMC and �18OMC
(�17 and 18OMC) are 0‰ for silicates, �120‰for ice, and – 80‰ for gas (Fig. 1A). The�17 and 18OMC values for H2O ice and CO gaswere chosen to be within the simulated rang-
es and to conserve the mean isotopic compo-sition of the bulk molecular cloud. The 16O-depleted nature of ice relative to silicates isconsistent with evidence from a primitivemeteorite. The most 16O-depleted knowncomponent formed in the solar system is theproduct of aqueous alteration of Fe,Ni-metalby H2O in the most primitive ordinary chon-drite, Semarkona (28).
A protoplanetary disk is formed by col-lapse of a molecular cloud core. In the outerregion of the disk, because of low tempera-tures (29), the primordial oxygen isotopiccompositions of the molecular cloud compo-nents are preserved (Fig. 1B). CO sublimeswhile preserving its own oxygen isotopecomposition outside the orbits of outer plan-ets, even in the case of frozen CO. In theinner region of the disk, H2O ice evaporates.During an early stage of disk evolution ac-companied by vigorous gas accretion, gas-dust fractionation is probably minor, and themean oxygen isotopic composition of the in-ner disk gas is reset to the value of the bulkmolecular cloud, �17 and 18OMC � 0‰. Be-cause transient heating events, such as the
formation of refractory inclusions and chon-drules, were common in the inner solar neb-ula (30), silicate grains would equilibratewith such gas and have similar oxygen iso-topic compositions.
As the gas accretion rate decreases, dust-gas fractionation processes begin to proceedin the disk. One such fractionation process isthe dust sedimentation toward the disk mid-plane (31) (Fig. 1D). In addition, dust parti-cles may preferentially migrate toward thecentral star (32), and ice in the dust evapo-rates after passing the snow line, releasing16O-depleted water vapor into the inner diskgas (33) (Fig. 1D). This increases the mean�17 and 18OMC of disk gas along the mixingline between the oxygen isotopic composi-tions of CO and of H2O ice (Fig. 1C), corre-lating with the degree of H2O enrichmentrelative to the H2O/CO ratio in the parentmolecular cloud (22). Although enrichmentof H2O by a factor of 10 is justified in thesolar nebula (34), even moderate enrichmentcan produce extreme 17O- and 18O-enrich-ment of the disk gas (Fig. 2). For example, ifthree times the H2O enrichment occurs (i.e.,
Fig. 1. Schematic diagram of oxygen isotope evolution from a molecular cloud to a protoplan-etary disk with dust sedimentation. (A) Oxygen isotopic compositions in a molecular cloud. CO(open circle) is the most abundant species next to H2 and He in a molecular cloud. UV radiationselectively destroys C17 and 18O, leaving behind CO enriched in 16O and producing atomicoxygen enriched in 17O and 18O. This heavy oxygen later becomes incorporated into water ice(snowflake). �17,18OMC values of 0‰, �120‰, and – 80‰ for silicate (solid circles), ice, andgas, respectively, are assumed. (B) Oxygen isotopic compositions in the outer disk. The oxygenisotopic composition produced in the molecular cloud is preserved in the individual phases inthe outer disk after accretion because of low temperature. (C) In the inner disk, oxygen isotopiccomposition of gas (J) shifts to a 16O-poor one. (D) In the disk, solid materials settle down tothe mid-plane and spiral into the proto-sun. Water ice evaporates inside the snow line (29),leading to the shift in oxygen isotopic composition shown in (C). Degrees of the shift dependon the H2O enrichment factor (Fig. 2) and on oxygen isotopic compositions of the individualphases in the molecular cloud. The relationship between � notation relative to SMOW and thatto the molecular cloud possibly corresponds to �17 and 18OSMOW � �17 and 18OMC – 50‰,assuming the traditional 16O-rich reservoir in the solar system. The setting of lighter silicatesand heavy disk gas with respect to oxygen isotopic composition in the inner disk is consistentwith meteoritic observations.
R E P O R T S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1764
if relative oxygen abundances of ice:gas are2 :1), the mean �17 and 18OMC of the inner diskgas will be about �50‰. Therefore, oxygenisotopic compositions of the disk gas arealtered easily by dust-gas fractionation pro-cesses (35). Silicate grains equilibrated withsuch H2O-enriched gas during transient heat-ing events would acquire isotope composi-tions with high �17 and 18OMC values (36).
Organic materials may also accommodatea significant fraction of oxygen. In hot mo-lecular cloud cores observed for high-massstar-forming regions, CO is probably deplet-ed because of conversion to refractory organ-ics (37). Free radical reactions in ices aredominant processes to form refractory organ-ics in molecular clouds (38). These organicsare interpreted as UV photolysis products inH2O ice contaminated with CO during theprevious cold evolutionary stage of a molec-ular cloud (20). Because oxygen contained insuch organics seems to come from H2O andCO, its isotope composition is expected tobe somewhere between those of both spe-cies, possibly �17 and 18OMC of �20‰ if a
1:1 contribution of H2O and CO is assumed.If we accept a refractory organic abun-
dance and composition in a comet nucleus(20), the oxygen abundance of organics willbe comparable to that of silicate (i.e., silicate:ice:organics:gas � 1:1.5 :1:2.5). Because re-fractory organics evaporate under higher tem-peratures than H2O, they may affect the meanoxygen isotopic composition of inner diskgases at high temperatures. Even though thisdiminishes the amount of change in the iso-topic composition because of H2O enrich-ment, the disk gas probably has 16O-poorcompositions (Fig. 2).
The proposed scenario can reproduce ox-ygen isotope heterogeneity in the inner solarnebula with an 17O- and 18O-enriched gas,i.e., 16O-depleted gas, relative to silicate dust,consistent with the conventional O isotopereservoirs inferred from meteorite studies (1).Under such an environment, the silicate dustevolves into an 16O-depleted compositionthrough isotope exchange with the surround-ing gas, because of transient heating events inthe nebula. Therefore, the average oxygenisotopic composition of the solar nebula nor-malized to the standard mean ocean water(SMOW) may be �17,18OSMOW � –50‰ orsmaller (39) (Fig. 1).
We have shown that even small massfractionation for CO and atomic O in themolecular cloud can explain the formation of16O-rich or -poor reservoirs observed for thesolar nebula. The 16O-rion or -poor reservoirscan easily form if we use larger mass frac-tionation factors as expected by chemicalmodels (16, 17) and observations (27) ofmolecular clouds. Thus, the 16O isotope vari-ations may not be unique to our solar systembut instead ubiquitous in any planetary sys-tem. A direct test of this scenario would be tomeasure the oxygen isotopic compositionsof cometary ices and that of solar wind.We predict the oxygen isotopic values as�17 and 18OSMOW � �50 to �200‰, –100 to–450‰, and –50‰ for cometary H2O, co-metary CO, and solar wind, respectively.
References and Notes1. R. N. Clayton, Annu. Rev. Earth Planet. Sci. 21, 115
(1993).2. S. Kobayashi, H. Imai, H. Yurimoto, Geochem. J. 37,
663 (2003).3. R. N. Clayton, R.W. Hinton, A. M. Davis, Philos. Trans.R. Soc. London Ser. A 325, 483 (1988).
4. L. R. Nittler, C. M. O. Alexander, J. Wang, X. Gao,Nature 393, 222 (1998).
5. M. H. Thiemens, J. E. Heidenreich, Science 219, 1073(1983).
6. M. H. Thiemens, Science 283, 341 (1999).7. Y. Kitamura, M. Shimizu, Moon Planets 29, 199
(1983).8. R. N. Clayton, Nature 415, 860 (2002).9. C. J. Lada, E. A. Lada, D. P. Clemens, J. Bally, Astrophys.
J. 429, 694 (1994).10. M. Ando et al., Astrophys. J. 574, 187 (2002).11. Dissociation of a molecule occurs through its excita-
tion to a certain bound state that is coupled to adissociative continuum. Predissociation is caused byinteraction between discrete levels of a given elec-
tronic state and the dissociative continuum of anoth-er electronic state.
12. J. Bally, W. D. Langer, Astrophys. J. 255, 143 (1982).13. Y.-H. Chu,W. D.Watson, Astrophys. J. 267, 151 (1983).14. A. E. Glassgold, P. J. Huggins,W. D. Langer, Astrophys.
J. 290, 615 (1985).15. E. F. van Dishoeck, J. H. Black, Astrophys. J. 334, 771 (1988).16. S.Warin, J. J. Benayoun, Y. P. Viala, Astron. Astrophys.
308, 535 (1996).17. P. Marechal, Y. P. Viala, L. Pagani, Astron. Astrophys.
328, 617 (1997).18. P. Marechal, Y. P. Viala, J. J. Benayoun, Astron. Astro-
phys. 324, 221 (1997).19. Condensation temperatures of H2O are �90 K in a
molecular cloud and �150 K in the solar nebula,whereas those of CO are �16 K in a molecular cloudand �25 K in the solar nebula (38).
20. J. M. Greenberg, Astron. Astrophys. 330, 375 (1998).21. D. P. Ruffle, H. Eric, Mon. Not. R. Astron. Soc. 324,
1054 (2001).22. H. Yurimoto, K. Kuramoto, Meteorit. Planet. Sci. 37,
A153 (2002).23. AV is a measure used to distinguish diffuse, translu-
cent, and dense clouds; AV � 2.5log10(IV0/IV), whereIV0 and IV are the intensities of visual light from abackground star before and after the transverse ofthe cloud.
24. D. C. B. Whittet, P. A. Gerakines, J. H. Hough, S. S.Shenoy, Astrophys. J. 547, 872 (2001).
25. E. A. Bergin et al., Astrophys. J. 539, L129 (2000).26. E. F. van Dishoeck, G. A. Blake, B. T. Draine, J. I. Lunine,
in Protostars and Planets III, E. Levy, J. I. Lunine, Eds.(Univ. of Arizona Press, Tucson, 1993), pp. 163–241.
27. Y. Sheffer, D. L. Lambert, S. R. Federman, Astrophys. J.574, L171 (2002).
28. B.-G. Choi, K. D. McKeegan, A. N. Krot, J. T. Wasson,Nature 392, 577 (1998).
29. D. J. Stevenson, J. I. Lunine, Icarus 75, 146 (1988).30. H. C. Connolly, S. G. Love, Science 280, 62 (1998).31. S. V. W. Beckwith, T. Henning, Y. Nakagawa, in Pro-
tostars and Planets IV, V. Mannings, A. P. Boss, S. S.Russell, Eds. (Univ. of Arizona Press, Tucson, AZ,2000), pp. 533–558.
32. S. J. Weidenschilling, J. N. Cuzzi, in Protostars andPlanets III, E. H. Levy, J. I. Lunine, Eds. (Univ. of ArizonaPress, Tucson, AZ, 1993), pp. 1031.
33. Because of partial support by the radial pressuregradient, disk gas tends to rotate with slightly lowervelocity than the Keplerian orbital motion. This caus-es the frictional loss of angular momentum of im-mersed solid particles in the disk gas, resulting intheir inward migration. The migration speed dependson the particle size and reaches a maximum of �100m/s at about a meter in diameter (32). The inwardradial velocity of gas (vg) can be estimated from massaccretion rate M as vg � M/(2�R�) where R is thedistance from the disk center and � is the gas columndensity. Taking M � 10�8 solar masses per year,which is typical for the disks around classical T-Tauristars (40), and � � 3 � 103 kg/m3 at R � 3astronomical units of the minimum-mass solar neb-ula (41), vg � �0.1 m/s. In such a disk, the inwardradial velocities of solid particles as small as �1 mmcould be several times faster than vg. Relative motionsbetween the snow line and gas-dust during the diskevolution will also influence the amount of H2O enrich-ment in the inner disk. As the disk accretion decays, thesnow line would move inward because of disk coolingand in some cases pass the migrating solid particles.However, the snow line cannot enter a warm zonedetermined by the radiative heating from the centralstar. Thus, the inward particle migration across thesnow line seems to occur unavoidably during disk evo-lution. Alternatively, H2O vapor could be depleted fromthe inner disk if the diffusive outward transport of H2Ovapor and the cold trap outside the snow line areeffective (29). However, because molecular diffusion isextremely slow, the main mechanism of the outwardtransport should be the turbulent diffusion. The turbu-lent flow also causes the inward gas flow because ofassociated turbulent viscosity. Taking into account theinward gas flow, H2O vaporized from the solid compo-nent migrating inward is eventually supplied into theinner disk. The cold trap mechanism can work onlywhen the solid component is sequestered into bodies
Fig. 2. �17 and 18OMC of inner disk gas as a func-tion of the H2O enrichment factor relative tomolecular cloud abundance. The H2O enrichmentfactor times the H2O/CO ratio in a molecularcloud represents the H2O/CO ratio in the diskgas, excluding chemical equilibria. The solid curverepresents a case that neglects refractory organ-ics as an oxygen carrier. Here we assume the�17 and 18OMC values of silicate, H2O ice, and COgas to be 0‰, �120‰, and –80‰, respective-ly, and their relative oxygen abundances in amolecular cloud to be 1:2:3. Significant 16O-depletion of the gas is expected even for smallH2O enrichments. Long and short-dashed curvesincorporate the effect of organics, providing thatthe �17 and 18OMC values of silicate, ice, organics,and gas are 0‰, �120‰, �20‰, and –80‰,respectively, and that the relative oxygen abun-dances are 1:1.5 :1:2.5 in the molecular cloud. Thelong-dashed curve indicates the case of highertemperature than the sublimation point of organ-ics, assuming the same enrichment factor withH2O. The short-dashed curve indicates the case ofthe temperature between sublimation points ofH2O ice and of organics. In either case, significant16O-depletion of the gas occurs for small H2Oenrichment factors.
R E P O R T S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1765
larger than kilometer-size, which have negligible radialdrift. Therefore, H2O enrichments in the inner diskwould be expected before the appearance of kilometer-size bodies in the outer disk.
34. J. N. Cuzzi, K. J. Zahnle, Astrophys. J., in press.35. Recently, UV dissociation of CO at high altitudes in
the disk has been numerically estimated (42). Lyonsand Young assume H2O ice as a carrier of the 16O-poor oxygen formed by their photodissociation pro-cess to generate 16O-poor gas in the disk midplanesimilar to an idea that we had presented in ourpreliminary study (22). However, the degree of frac-tionation by the disk photochemistry is dependent onmany unconstrained factors, including far-UV flux,the intensity of vertical eddy mixing, and the effi-ciency of H2O formation. A more detailed studycoupled with disk dynamics is needed to evaluate thecontribution of their CO dissociation at high altitudesin the disk to oxygen isotopic heterogeneity observedin the solar system.
36. The bulk differences in oxygen isotopic composi-tion observed among the meteorite groups andplanets (1) could be explained by accretion at
different times or by the incorporation of differentamounts of nonvaporized water ice and solids withdifferent degrees of the solid-gas equilibration. Thesolid-gas equilibration and the evolution of oxygenisotopic compositions of the gas in the inner regionof the disk may have been recorded by refractoryinclusions and chondrules in primitive meteorites.
37. S. Kurtz, R. Cesaroni, E. Churchwell, P. Hofner, C. M.Walmsley, in Protostars and Planets IV, V. Mannings,A. P. Boss, S. S. Russell, Eds. (Univ. of Arizona Press,Tucson, 2000), pp. 299–326.
38. W. D. Langer et al., in Protostars and Planets IV, V.Mannings, A. P. Boss, S. S. Russell, Eds. (Univ. ofArizona Press, Tucson, 2000), pp. 29–57.
39. We use this value according to the traditional16O-enrichment observed in most Ca-A1–rich in-clusions (1). Recently, a chondrule having twice thetraditional enrichment (�17 and 18OSMOW of about–75‰) has been reported (2). Although such chon-drules are rare, its least fractionated bulk chemicalcomposition from the solar abundance suggeststhat the average oxygen isotopic composition ofsilicate in the solar system was originally more
enriched in 16O than the traditional value. Accord-ing to our model, such an extreme 16O-rich chon-drule is interpreted as a closer representation ofthe pristine solar nebula value, implying that theordinary refractory inclusions are no longer repre-sentative of the bulk solar nebula but moderatelyreprocessed by the interaction with the 17O- and18O-rich H2O.
40. N. Calvet, L. Hartmann, S. E. Strom, in Protostars andPlanets IV, V. Mannings, A. P. Boss, S. S. Russell, Eds.(Univ. of Arizona Press, Tucson, 2000), pp. 377–399.
41. C. Hayashi, K. Nakazawa, Y. Nakagawa, in Protostarsand Protoplanets II, D. C. Black, M. S. Matthews, Eds.(Univ. of Arizona Press, Tucson, 1985), pp. 1100–1153.
42. J. R. Lyons, E. D. Young, Lunar Planet. Sci. 35, 1970(2004).
43. We thank T. J. Fagan, A. N. Krot, and E. R. D. Scott forhelpful discussion and improvement of the Englishand two anonymous reviewers for helpful comments.Supported by Monbu-Kagaku-sho grants.
2 June 2004; accepted 2 August 2004
Middle Miocene Southern OceanCooling and AntarcticCryosphere Expansion
Amelia E. Shevenell,* James P. Kennett, David W. Lea
Magnesium/calcium data from Southern Ocean planktonic foraminifera demon-strate that high-latitude (�55°S) southwest Pacific sea surface temperatures(SSTs) cooled 6° to 7°C during the middleMiocene climate transition (14.2 to 13.8million years ago). Stepwise surface cooling is paced by eccentricity forcing andprecedes Antarctic cryosphere expansion by �60 thousand years, suggesting theinvolvement of additional feedbacks during this interval of inferred low-atmo-spheric partial pressure of CO2 (pCO2). Comparing SSTs and global carbon cyclingproxies challenges the notion that episodic pCO2 drawdown drove this majorCenozoic climate transition. SST, salinity, and ice-volume trends suggest insteadthat orbitally paced ocean circulation changes altered meridional heat/vapor trans-port, triggering ice growth and global cooling.
The middle Miocene climate transition(MMCT), 14.2 to 13.8 million years ago(Ma), is one of the three major steps inEarth’s Cenozoic climate evolution (1–3).The �1‰ increase in the oxygen-isotopiccomposition (�18O) of benthic foraminiferadescribes a combination of Antarctic icegrowth and global cooling at �14 Ma, as isalso indicated by Southern Ocean ice-rafteddetritus, eustatic change, and the fossil record(1–6). However, because �18O records bothtemperature and global ice volume, funda-mental questions and uncertainties exist con-cerning the magnitude and phasing of middleMiocene ice growth and cooling. The devel-opment of Mg/Ca, an independent paleotem-perature proxy measured on the same forami-niferal calcite (CaCO3) as �18O, has facilitat-
ed isolation of the ice-volume component of�18O records (7–12). The Mg/Ca content offoraminifera increases exponentially withtemperature (�9 � 1% per 1°C) and is rela-tively insensitive to salinity and ice-volumefluctuations (7, 8). Low-resolution pairedbenthic foraminifer Mg/Ca and �18O studiesdesigned to constrain the timing and magni-tude of pre-Quaternary ice-volume fluctua-tions suggest substantial Antarctic ice growth(�0.85‰) and a concomitant deep oceancooling (2°C to 3°C) during the MMCT (11,12). The magnitude of Antarctic ice growthand rapidity of this climate transition [�0.5million years (My)] suggests that Earth’s cli-mate system was highly sensitive to oceanic,atmospheric, and cryospheric feedbacks.
Ocean circulation and atmospheric pCO2
variations are often cited as potential cata-lysts of the MMCT (13–17). Large-scale re-organizations of ocean circulation driven byatmospheric circulation changes and/or tec-tonic reorganizations of gateway regions mayhave altered poleward heat and moisture
transport, resulting in Antarctic ice growthand global cooling (13–15). Ocean circula-tion hypotheses are supported by �13C proxyevidence (14, 15, 18, 19) and the timing oftectonic events in the eastern Tethys/Indone-sia (4, 20) and the North Atlantic (13). Alter-natively, atmospheric pCO2 drawdown,through organic carbon sequestration on themid-latitude continental margins (16) and/orenhanced silicate weathering rates (17), mayhave driven Antarctic ice-sheet expansionand cooling at �14 Ma. Support for this“Monterey Hypothesis” comes from thick,organic carbon-rich Miocene sedimentary se-quences around the Pacific Rim (4, 16) and acorresponding � 1‰ increase in global deepsea �13C (4, 16, 21, 22). A potential compli-cation of the hypothesis is revealed by paleo-pCO2 estimates (23–25), which indicate thatatmospheric pCO2 levels declined �3 Mybefore the MMCT and provide little supportfor either elevated atmospheric pCO2 duringthe warm Miocene climatic optimum (MCO)(17 to 14 Ma) or a semipermanent atmospher-ic pCO2 decrease at the MMCT. These esti-mates indicate that factors other than thoserelated to global carbon cycling may contrib-ute to this major Cenozoic climate transition.To evaluate the processes and feedbacks in-volved in the MMCT, detailed information isneeded regarding the phasing of carbon cy-cling, Antarctic ice growth, and high-latitudeoceanic/atmospheric cooling. Acquiring thisinformation has thus far proven difficult be-cause of the limited availability of CaCO3-rich Southern Ocean sediments and the lackof an unambiguous paleotemperature proxy.
Here, we present an independent record ofmiddle Miocene high-latitude SouthernOcean sea surface temperature (SST). To es-tablish the thermal and hydrographic re-sponse of Southern Ocean surface waters andthe phasing of high-latitude SST change,Antarctic cryosphere expansion, and globalcarbon cycling between �17 and 13 Ma, we
Department of Geological Sciences and Marine Sci-ence Institute, University of California, Santa Barbara,CA 93106–9630, USA
*To whom correspondence should be addressed. E-mail: [email protected]
R E P O R T S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1766
generated paired Mg/Ca and �18O recordsfrom surface dwelling planktonic foraminiferGlobigerina bulloides in conjunction withbenthic foraminifer (Cibicidoides mundulus)�18O and �13C records at Ocean DrillingProgram (ODP) Holes 1170A (47°90’S,146°02.98’E; 2704 m) and 1171C (48°30’S,149°06.69’E; 2150 m) on the South TasmanRise (STR) (26) (Fig. 1). Plate tectonic re-constructions indicate that Sites 1170 and1171 were situated at �55°S in the middleMiocene (27), with calculated paleodepths of2100 m and 1600 m, respectively (28). Weused G. bulloides for several reasons. First, awell-defined modern subantarctic G. bul-loides Mg-temperature calibration exists (7).Second, previous studies demonstrate theutility of G. bulloides Mg/Ca in reconstruct-ing Quaternary subantarctic SSTs (7, 9). Fi-nally, G. bulloides is continuously presentthrough both STR middle Miocene sequences(26). Hole 1171C Miocene G. bulloides Mg/Ca ranges between �1.7 and 4.3 mmol/mol(Fig. 2 and table S1); minimum Mg/Ca val-ues are similar to those from subantarcticcore tops (7, 9). The main feature of the G.bulloides Mg/Ca record is the 1.8 mmol/molpoint-to-point decrease centered at 166.4 mbelow sea floor (mbsf) that marks the transi-tion from relatively high to relatively lowMg/Ca. Three step-like features are superim-posed on this transition (Fig. 2). Hole 1171CG. bulloides �18O ranges between �0.0‰and �1.8‰ (29) (Fig. 2 and table S1). Themain feature of the G. bulloides �18O recordis the 0.9‰ point-to-point increase centeredat 165.6 mbsf that marks the transition tomore positive �18O values. The step-likestructure of the Mg/Ca transition does notappear in the G. bulloides �18O record, whichreflects ice volume and salinity influences inaddition to temperature.
Diagenesis and dissolution may potentiallyalter the primary Mg/Ca signal encoded inplanktonic foraminiferal calcite and, thus, theinferred SST record (8–11) (SOM Text). Sev-eral lines of evidence suggest that these pro-cesses have not biased our STR middle Mio-cene Mg/Ca values: (i) G. bulloides ultrastruc-tures are visible, and shells do not exhibit ex-tensive pitting, fragmentation, infilling, orovergrowth; (ii) the average CaCO3 content ofthe middle Miocene ooze is stable at �94% byweight (26) as a result of the intermediate STRpaleodepths (28); and (iii) benthic and plank-tonic foraminifers exhibit interspecific �18Oand �13C offsets (30).
We converted STR G. bulloides Mg/Cavalues to temperatures using the calibrationof Mashiotta et al. (7): SST � ln(Mg/Ca/0.474)/0.107 (SE, �0.8°C). This calibrationsuccessfully estimates subantarctic Pacific(45°S to 56°S) and Indian Ocean (43°S) aus-tral spring SSTs in both the modern andQuaternary (7, 9). As ours is the first pre-
Quaternary study employing this calibration,we assume that the environmental preferenc-es of middle Miocene subantarctic G. bul-loides and physical processes governing Mguptake are similar to those in modern subant-arctic G. bulloides. These processes and sea-water Mg/Ca (31) may have changed throughtime and could contribute an additional un-certainty of up to 3°C in the conversion ofMg/Ca to absolute temperature (SOM Text).However, this uncertainty would not affectthe magnitude of inferred temperature shiftson time scales �1 My. Age models derivedfrom magnetostratigraphy, biostratigraphy,and stable isotope datums (32) provide the
chronologic framework for the STR records(SOM Text).
Mg/Ca evidence from Hole 1171C indi-cates that regional SSTs were �2°C coolerafter �14 Ma (14.7 � 1.1°C; 13.9 to 12 Ma)than during the preceding MCO (17.0 �1.2°C; 17 to 14 Ma) (Fig. 3) (3, 4). Paleobo-tanical and faunal paleotemperature estimatesfrom southern Australia and New Zealandsupport this trend and are similar to, or slight-ly cooler than, G. bulloides Mg/Ca-derivedSST estimates (4, 33). The major feature ofthe STR SST record is a �7°C (point-to-point) transition (14.2 to 13.9 Ma) from thewarmest MCO to cooler post-MMCT SSTs
170°E160°140°E
30°S
50°S
Australia
Tasmania
TF
ODP 1170A
16
14
12
108
64
18
20
22
24
ODP 1171C
SAF
STC
150°
40°S
NewZealand
EAC
ACC
Fig. 1. Annual average SSTs inthe subantarctic southwest Pa-cific (39) with Ocean DrillingProgram (ODP) South TasmanRise (STR) sites indicated. ODPSite 1171 is located at the inter-section of the southward-flow-ing East Australian Current (EAC)and the eastward-flowing Ant-arctic Circumpolar Current(ACC), one of three locationswhere heat is introduced to theSouthern Ocean (26). ODP Site1170 is located 50 km northwestof Site 1171, beyond the influ-ence of the EAC (26). In the mid-dle Miocene, the STR was situat-ed at �55°S, 5° to 7° south of itspresent location (27 ). Back-tracked middle Miocene pa-leodepths of Sites 1170 and1171 are 2100 m and 1600 m,respectively (28). Currently, STRhydrography is controlled by the Subtropical Convergence (STC) to the north and the Subantarctic Front(SAF) to the south. Seasonal SST variation is �4°C (26, 39). G. bulloides calcifies in the mixed layerduring the austral spring when regional surface temperatures range between 8°C and 12°C (9, 39).
120 140 160 180 200
0
1.0
Depth (mbsf)
G. b
ullo
ides
Mg
/Ca
(mm
ol/m
ol)
G. b
ullo
ides
δ18
O (
‰)
2.0
4.5
1.5
2.5
3.51.5
0.5
Fig. 2. Climate proxy data from South Tasman Rise (STR) ODP Hole 1171C (48°30’S, 149°06.69’E;2150 m). The Mg/Ca record was generated on planktonic foraminifer species G. bulloides at 20-cmintervals from 125 to 154mbsf and from 154 to 207 mbsf and at 10-cm intervals between 154 and172 mbsf. Each point represents an average of one to four analyses; pooled SD of all replicates(df � 64) is �0.21 mmol/mol (�7.8%). Measured modern southwest Pacific core top Mg/Ca is�1.6 mmol/mol (9). Oxygen isotope (�18O) data were generated from G. bulloides at 10-cmintervals between 125 and 207 mbsf. The black arrow denotes the midpoint of the major 1.8mmol/mol Mg/Ca transition, and the gray arrow denotes the midpoint of the 0.9‰ G. bulloides�18O transition. Gaps in the data are due to incomplete core recovery (26 ).
R E P O R T S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1767
(Fig. 3). Inferred orbital-scale [�400 and 100thousand years (ky)] SST variability is par-ticularly pronounced during the MMCT.Cooling occurred in three distinct steps (mid-points, 14.2, 14.0, and 13.9 Ma) and wasfollowed by an interval of relatively coldSSTs (13.7 � 1.1°C; 13.9 to 13.8 Ma) (Figs.3 and 4). At �13.8 Ma, regional SSTs warmby �2°C to 3°C and remain relatively stableuntil �12 Ma. We confirmed the Hole 1171CSST estimates by measuring G. bulloidesMg/Ca at a second STR location, Hole1170A [�54°S (27); 2100 m (28)] (Figs. 1and 3, table S2), with a different depositionalhistory (26). Similarities in both magnitude(�0.5°C) and structure of the two records(Fig. 3) further support our interpretation ofSTR G. bulloides Mg/Ca as a primary climatesignal. We attribute several offsets betweenthe records to age model and sampling reso-lution differences (30) (SOM Text).
Large-amplitude SST fluctuations overthe STR suggest substantial reorganization ofSouthern Ocean surface waters during theMMCT. One possible explanation is an orbit-ally paced intensification of the AntarcticCircumpolar Current (ACC) system, perhapsrelated to increased westerly wind strength.This idea is supported by a paleobotanicrecord of regional wind strength (4, 34), sub-stantial evidence for increased meridionalthermal gradients (4), the timing of majorSouthern Ocean unconformities (4, 5), and
STR surface water �18O (�18Ow). We usedHole 1171C G. bulloides Mg/Ca SST and�18O (table S1) to calculate �18Ow (7, 8)(SOM Text) (fig. S1), which should reflectsome combination of ice volume and localsalinity effects. Large SST fluctuations dur-ing the MMCT obscure the G. bulloides �18Oincrease, which indicates that STR �18Ow
likely reflects regional salinity variations.Strict interpretation of the �18Ow results sug-gests a gradual freshening of regional surfacewaters between 14.2 and 13.8 Ma, consistentwith enhanced ACC strength and the result-ant increased influence of subantarctic sur-face waters over the STR. A notably similarpattern of oceanographic change is recog-nized in the southwest Pacific during Quater-nary glaciations (9, 35).
Orbital-scale cyclicity (400 and 100 ky) isinferred in the STR records of G. bulloidesMg/Ca and C. mundulus �18O and �13C. Thiscyclicity indicates a potential role for Mi-lankovitch forcing during the MMCT, whichsuggests that Earth’s climate system was par-ticularly sensitive to forcing at eccentricityfrequencies between �15 and 13.5 Ma. Com-parison of orbital curves (36) to untuned STRSST and C. mundulus �18O, an ice-volumeproxy (32) (SOM Text), reveals that theMMCT occurred within an interval of highobliquity and moderate eccentricity variance(Fig. 4) (36). This relationship suggests that,at 14.2 Ma, Antarctic ice sheets were large
enough to survive warm summer orbital con-figurations but small enough to respond dy-namically to orbital forcing (37). Surfacecooling generally corresponds with long-pe-riod (�400 ky) eccentricity minima between14.2 and 13.8 Ma (which are similar in am-plitude to previous and subsequent minima)and precedes Antarctic ice growth by �60 ky(as judged by the midpoints of the majorMg/Ca and C. mundulus �18O transitions).Our data suggest that orbital forcing pacedboth Southern Ocean SSTs and Antarctic icegrowth during the MMCT. There is, howev-er, no obvious orbital anomaly akin to thatrecognized at the Oligocene/Miocene bound-ary (38), and, assuming a synchronous atmo-spheric and SST response, the substantialtime lag (�60 ky) between orbital forcingand ice growth supports the notion that addi-tional feedbacks (e.g., carbon cycling, oceancirculation, and/or ice/albedo feedbacks) maybe required for substantial and rapid Antarc-tic ice growth. Heightened sensitivity to ec-centricity forcing between 14.2 and 13.8 Maand the phasing of SST and ice volume(�18O) are clues to identifying the feedbacksinvolved in this climate threshold.
Model results stress a fundamental rolefor atmospheric pCO2 in Cenozoic climatechange and indicate that the Antarctic cryo-sphere may react sensitively to climate feed-backs only when atmospheric pCO2 is rela-tively low and within some narrowly defined
G. b
ullo
ides
Mg
/Ca
(mm
ol/m
ol)
SS
T (
°C)
G. b
ullo
ides
δ18
O (
‰)
C. m
un
du
lus
δ18
O (
‰)
4.0
3.5
3.0
2.5
2.0
1.5
12
14
16
18
20
ODP 1171ODP 1170
12 13 14 15 16 17Age (Ma)
2.5
1.5
0
1.0
2.0
2.0
3.0
0.5
1.5
Fig. 3. Hole 1171C mid-dle Miocene (12 to 17Ma) G. bulloides �18O,SST, and benthic fora-minifer (C. mundulus)�18O (32) records ver-sus age.Mg/Ca–derivedSSTs from Hole 1170A(open circles) are plot-ted with the Site 1170age model. Age modelsat Sites 1170 and 1171were constructed usingmagnetostratigraphy,biostratigraphy, andstable isotope datums(26, 32). The G. bul-loides Mg/Ca valueswere converted to SSTby using the equation ofMashiotta et al. (7).Both the Mg/Ca andSST scales are given.The C. mundulus �18Orecord serves as a gen-eral proxy for Antarcticice volume (11, 30)(SOM Text).
R E P O R T S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1768
range (37). Sensitivity to eccentricity forcingis apparent in many middle Miocene �13Crecords between 17 and 13.5 Ma (4, 14, 15,18, 21, 22), which suggests at least some rolefor the carbon cycle in the MMCT. However,the �3 My discrepancy between the initialatmospheric pCO2 decline (23, 24) and theMMCT has shifted focus to the role of epi-sodic pCO2 drawdown, associated with morepositive �13C carbon maxima (CM) events, intriggering this major climate step (21). Mod-erate resolution records suggest that CMevents, which are attributed to climate-in-duced variations in marine organic carbonsequestration, co-vary with analogous �18Oevents at the 400-ky frequency (14, 15, 18).Comparison of STR G. bulloides Mg/Ca to C.
mundulus �18O (ice volume) and �13C, ageneral proxy for carbon cycling and atmo-spheric pCO2, reveals that Southern Oceansurface-water cooling and Antarctic icegrowth occurred between CM5 and CM6 dur-ing an interval of increasing pCO2 (Fig. 4)(23). This sequence of change challenges thenotion that episodic pCO2 drawdown was theprimary forcing that triggered the MMCT,again implying that other feedbacks (e.g.,ice/albedo) played a more significant role inthis climate transition. Our records also indi-cate that CM6, one of the largest CM events,corresponds with maximum Antarctic icevolume and a slight warming of the highsouthern latitudes. This relationship raises thepossibility that feedbacks related to Antarctic
cryosphere expansion may have exerted con-trol over the global carbon cycle throughenhanced ventilation of intermediate anddeep ocean waters and falling sea levels (4, 6,23). The long-term trend observed in theglobal �13C record after the rapid expansionof Antarctic ice volume supports this inter-pretation (3).
Our results demonstrate that STR SSTscooled 6°C to 7°C between 14.2 and 13.8 Ma,revealing that the Southern Ocean was a dy-namic component of the MMCT. Eccentricity-paced Southern Ocean surface cooling andfreshening suggest that atmospheric/oceaniccircumpolar circulation intensified in responseto orbital forcing, increasingly thermally isolat-ing Antarctica during the MMCT (14.2 to13.8Ma). Middle Miocene intensification of theACC may have played a major role in Cenozoicclimate evolution, both directly through chang-es in meridional heat transport and indirectlythrough changes in vapor transport. We specu-late that sensitivity to eccentricity forcing in-creased at 14.2 Ma, immediately followingpeak warmth of the MCO (23–25) as a resultboth of low atmospheric pCO2 (37) and of afundamental reorganization of the climate sys-tem, specifically a tectonically mediated reduc-tion in meridional heat/vapor transport relatedto the constriction of the Eastern Tethys at �15Ma (4, 14, 20). The presence of 100-ky vari-ability (14.2 to 13.8 Ma) and a rare shift ineccentricity cadence between 15 and 14 Ma(36) are intriguing, and future efforts shouldfocus on understanding the evolution of theclimate spectrum on orbital time scales duringthe MMCT.
References and Notes1. N. J. Shackleton, J. P. Kennett, in Initial Reports of the
Deep Sea Drilling Project (U.S. Government PrintingOffice, Washington, DC, 1975), vol. 29, pp. 743–755.
2. K. G. Miller, R. G. Fairbanks, G. S. Mountain, Pale-oceanography 2, 1 (1987).
3. J. Zachos, M. Pagani, L. Sloan, E. Thomas, K. Billups,Science 292, 686 (2001).
4. B. P. Flower, J. P. Kennett, Palaeogeogr. Palaeoclima-tol. Palaeoecol. 108, 537 (1994).
5. J. P. Kennett, P. F. Barker, Proc. Ocean Drill. ProgramSci. Results 113, 937 (1990).
6. B. U. Haq, J. Hardenbol, P. Vail, Science 235, 1156 (1987).7. T. A. Mashiotta, D. W. Lea, H. J. Spero, Earth Planet.
Sci. Lett. 170, 417 (1999).8. D.W. Lea, D. K. Pak, H. J. Spero, Science 289, 1719 (2000).9. K. Pahnke, R. Zahn, H. Elderfield, M. Schulz, Science
301, 948 (2003).10. Y. Rosenthal, G. P. Lohmann, Paleoceanography 17,
1044 (2002).11. C. H. Lear, H. Elderfield, P. A. Wilson, Science 287,
269 (2000).12. K. Billups, D. P. Schrag, Paleoceanography 17, 1003 (2002).13. D. Schnitker, Nature 284, 615 (1980).14. F. Woodruff, S. M. Savin, Paleoceanography 4, 87
(1989).15. J. D. Wright, K. G. Miller, R. G. Fairbanks, Paleocean-
ography 7, 357 (1992).16. E. Vincent, W. H. Berger, in The Carbon Cycle andAtmospheric CO2: Natural Variations Archean toPresent, E. T. Sundquist, W. S. Broecker, Eds. (Ameri-can Geophysical Union, Washington, DC, 1985), vol.32, pp. 455–468.
17. M. E. Raymo, Paleoceanography 9, 399 (1994).
200
240
280
pC
O2 (
pp
mv)
SS
T (
°C)
C. m
un
du
lus
δ13
C (
‰)
C. m
un
du
lus
δ18
O (
‰)
12
14
16
18
20
13 14 15Age (Ma)
1.0
2.0
2.0
2.5
3.0
CM5
CM6
1.5
0.06
0.04
0.02
0
Ecc
entr
icit
y
0.38
0.4
0.42
Ob
liqu
ity
Fig. 4. Expanded view of the 13-to 15-Ma interval. Site 1171SSTs are compared with C. mun-dulus �18O and �13C records(32). Orbital solutions (36) areplotted; eccentricity (black) andobliquity (gray). Paleo-pCO2 esti-mates derived from southwestPacific alkenone �13C (23); max-imum (solid line) and minimum(dashed line) estimates are plot-ted. All records are plotted onthe Site 1171 age scale (32)(SOM Text). Midpoints of theSST and C. mundulus �18O tran-sitions are 14.07 Ma (black ar-row) and 14.01 Ma (gray arrow),respectively. The final �13C in-crease of the “Monterey” �13Cexcursion (CM6) begins at 13.8Ma and terminates at 13.6 Ma.
R E P O R T S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1769
18. B. F. Flower, J. P. Kennett, Paleoceanography 10, 1095(1995).
19. I. R. Hall et al., Paleoceanography 18, 1040 (2003).20. K. J. Hsu, D. Bernoulli, in Initial Reports of the Deep
Sea Drilling Project (U.S. Government Printing Office,Washington, DC, 1975), vol. 42, pp. 943–950.
21. B. F. Flower, J. P. Kennett, Geology 21, 877 (1993).22. D. A. Hodell, F.Woodruff, Paleoceanography 9,405 (1994).23. M. Pagani, M. A. Arthur, K. H. Freeman, Paleoceanog-
raphy 14, 273 (1999).24. P. N. Pearson, M. R. Palmer, Nature 406, 695 (2000).25. D. L. Royer et al., Science 292, 2310 (2001).26. N. F. Exon et al., Proc. Ocean Drill. Prog., Init. Rep.
(Ocean Drilling Program, College Station, TX 2001),vol. 189.
27. L. A. Lawver, L. M. Gahagan, M. F. Coffin, in TheAntarctic Paleoenvironment: A Perspective on GlobalChange, J. P. Kennett and D. A. Warnke, Eds. (Amer-ican Geophysical Union, Washington, DC, 1992), pp.7–30.
28. J. G. Sclater, L. Meinke, A. Bennett, C. Murphy, in The
Miocene Ocean: Paleoceanography and Biogeogra-phy, J. P. Kennett, Ed. ( The Geological Society ofAmerica, Boulder, CO 1985), pp. 1–21.
29. Materials and methods are available as supportingmaterial on Science Online.
30. A. E. Shevenell, unpublished data.31. B. Wilkinson, T. Algeo, Am. J. Sci. 289, 1158 (1989).32. A. E. Shevenell, J. P. Kennett, in The Cenozoic South-
ern Ocean: Tectonics, sedimentation, and climatechange between Australia and Antarctica, N. F. Exon,J. P. Kennett, M. J. Malone, Eds. (American Geophysi-cal Union, Washington, DC, in press).
33. I. R. K. Sluiter, A. P. Kershaw, G. R. Holdgate, D.Bulman, Int. J. Coal Geol. 28, 277 (1995).
34. S. Locker, E. Martini, Geol. Rundsch. 78, 1165 (1989).35. F. Lamy et al., Science 304, 1959 (2004).36. J. Laskar et al., Astron. Astrophys., in press.37. R. M. DeConto, D. Pollard, Nature 421, 245 (2003).38. J. C. Zachos, N. J. Shackleton, J. S. Revanaugh, H.
Palike, B. P. Flower, Science 292, 274 (2001).39. S. R. Rintoul, J. L. Bullister, Deep-Sea Res. 46, 1417
(1999).
40. Supported by NSF grant OPP0229898 to J. P. Kennettand JOI/USSSP postcruise funds to A. E. Shevenell.This research used samples provided by the OceanDrilling Program. Mass spectrometer operation/sup-port by G. Paradis and H. Berg and laboratory assist-ance from K. Thompson were critical to the successof this study. We thank the Gulf Coast Repositorystaff for providing samples; I. Hendy, M. Hommeyer,P. Martin, and D. Pak for discussion; and reviewers forsuggestions.
Supporting Online Materialwww.sciencemag.org/cgi/content/full/305/5691/1766/DC1Materials and MethodsSOM TextFig. S1Tables S1 and S2References
7 May 2004; accepted 10 August 2004
Crystal Structure of a SharkSingle-Domain Antibody V Region
in Complex with LysozymeRobyn L. Stanfield,1* Helen Dooley,3* Martin F. Flajnik,3
Ian A. Wilson1,2†
Cartilaginous fish are the phylogenetically oldest living organisms known topossess components of the vertebrate adaptive immune system. Key to theirimmune response are heavy-chain, homodimeric immunoglobulins callednew antigen receptors (IgNARs), in which the variable (V) domains recognizeantigens with only a single immunoglobulin domain, akin to camelid heavy-chain V domains. The 1.45 angstrom resolution crystal structure of the typeI IgNAR V domain in complex with hen egg-white lysozyme (HEL) revealsa minimal antigen-binding domain that contains only two of the threeconventional complementarity-determining regions but still binds HEL withnanomolar affinity by means of a binding interface comparable in size toconventional antibodies.
The cartilaginous fish (sharks, skates, rays,and chimeras) diverged from a common an-cestor with other jawed vertebrates approxi-mately 500 million years ago and includeover 700 extant species. Nevertheless, theypossess an adaptive immune system based onimmunoglobulin (Ig), T cell receptors(TCRs), and the major histocompatibilitycomplex. Three immunoglobulin isotypeshave been identified in cartilaginous fish: twostandard heavy (H)-light (L)-chain isotypes,designated IgM and IgW (IgW is also calledIgX or IgNARC); and an atypical isotype,
IgNAR. IgNAR is an H-chain homodimerthat does not associate with L chain (1, 2),unlike conventional human and murine anti-
bodies (Fig. 1). Each H chain has one vari-able (V) and five constant (C) domains.Electron microscopy studies of IgNAR haverevealed that their V regions are single do-mains, tethered to the C domains by means offlexible hinge-like regions (2). The V regionsof IgNAR are not closely related to the VH
regions of either shark IgM or IgW in phy-logenetic tree analyses; rather, they clusterwith the V regions of TCR or immunoglob-ulin L chains (1, 3).
In addition to the two canonical cys-teines typical of immunoglobulin domains,IgNAR V domains carry a number of non-canonical cysteines that enable classifica-tion into two closely related subtypes, I andII. Type II V regions have an additionalcysteine in complementarity-determiningregions (CDRs) 1 and 3, which have beenproposed to form a domain-constrainingdisulfide bond, akin to those observed incamelid H-chain V (VHH) domains (2, 4),whereas the extra cysteines in type I Vregions are in framework regions (FRs) 2and 4, and another two or four cysteines are
1Department of Molecular Biology, 2Skaggs Institutefor Chemical Biology, The Scripps Research Institute,10550 North Torrey Pines Road, La Jolla, CA 92037,USA. 3Department of Microbiology and Immunology,University of Maryland at Baltimore, Baltimore, MD21201–1559, USA, and the National Aquarium inBaltimore, 501 E. Pratt Street, Baltimore, MD 21202,USA.
*These authors contributed equally to this work.†To whom correspondence should be addressed. E-mail: [email protected]
Fig. 1. Schematic representationof the overall IgG and IgNAR ar-chitectures. (A) A conventionalIgG is composed of two H chains(blue) and two L chains (yellow)that assemble to form one Fcand two Fab regions or superdo-mains. The H chain has three Cdomains (CH1, CH2, and CH3)and one V domain (VH), whereasthe L chain has one C domain(CL) and one V domain (VL). TheV region is made up of two im-munoglobulin domains (VH andVL). (B) IgNAR has only two Hchains, each consisting of one V and five C domains, where the V domainis unpaired and constitutes a single-binding module. The IgG and theIgNAR domains are represented by their harmonic surfaces generated fromatomic coordinates (27); the IgNAR C domains are represented by ovalsbecause their structures are unknown.
R E P O R T S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1770
in CDR3. These CDR3 cysteines are usu-ally encoded by the diversity (D) regions intheir preferred reading frame (2) and areunder strong selection in the primary rep-ertoire (5). A deletion in the FR2-CDR2region gives the IgNAR V domain itscharacteristically small size (�12 kD). Fur-thermore, somatic mutations that are found inthe CDR1 of type II and in the shortenedFR2-CDR2 region of type I appear to corre-late with the acquisition and particular loca-tion of these extra disulfides in shark Vregions (5).
IgNAR genes are found in the “clusterconfiguration” typical of cartilaginous fishimmunoglobulins (6), with each cluster con-taining a single V region, three diversity el-
ements, and a single joining gene (1). Be-cause rearrangement only occurs within acluster (1, 6–8) and only a single functionalcluster is present for each IgNAR type I ortype II (1, 9), diversity encoded by the Vgermline genes is severely limited. However,the repertoire is expanded greatly through thegeneration of enormous diversity in CDR3through four rearrangement events, which in-clude nucleotide (N)–region additions at eachjoining region, and by a high rate of antigen-driven somatic hypermutation (10).
Dimeric H-chain antibodies are alsopresent in camels and llamas, where each Hchain contains one VHH domain and two Cdomains. Unlike IgNAR H chains, which arenot known to have ever associated with L
chains, camel H-chain antibodies have losttheir ability to associate with L chain as aresult of a deletion of their CH1 domains andmodification of VH residues that would nor-mally interact with VL in conventional anti-bodies (11). Crystal and nuclear magneticresonance structures for camel and llamaVHH single domains (12–24) have inspiredantibody engineering of single-domain anti-gen-binding fragments for use in biotechnol-ogy and medicine (25).
The IgNAR V region clone HEL-5A7 wasselected from a phage-displayed library de-rived from a nurse shark (Ginglymostomacirratum) immunized with HEL. The HEL-5A7 single domain is highly stable, highlyspecific, and binds HEL with nanomolar af-finity (26). The crystal structure of the Ig-NAR HEL-5A7 at 1.45 Å resolution is pre-sented here (27) (Fig. 2 and table S1). Com-parison of this shark IgNAR V domain withantibody and TCR immunoglobulin domainsfrom higher vertebrates (Fig. 3) now permitsmore informed speculation about the originsand evolution of these immunologically im-portant antigen-binding receptors.
The IgNAR V domain has an immuno-globulin � sandwich fold (Figs. 2A and 3A)consisting of only 8 � strands, rather thanthe 10 in a conventional antibody or TCR Vdomain, because of the deletion of the Cand C strands that normally compriseCDR2 (Fig. 3). As in CL domains, the Cstrand connects directly to the D strand(Fig. 3, A and D). The CDR3 loop is long(28) compared with most human and espe-cially murine CDR H3s, but it is of averagelength for IgNAR type I V regions [15 to 27residues (5, 26)]. The type I IgNAR CDR3contains unusual disulfide bonds [N35(FR2) to N92 (CDR3) and N97 (CDR3) toN104 (FR4)] (Fig. 2A) that constrain theCDR3 loop to fold over the outside sheetthat would usually associate with VL (Ig-NAR and lysozyme residues are designatedby N- and L-chain identifiers, respective-ly). CDR3 residues N93 to N99 form a 310
helix, similar to CDR3 conformations inseveral camelid VHH domains.
The IgNAR V domain shares featureswith several types of vertebrate immunoglob-ulin domains, making it difficult to classify.Sequence homology is highest (�35% iden-tity) between IgNAR V and TCR V� or im-munoglobulin V� chains, whereas structuralhomology is greatest with V�, VL, and VH
domains (29). From a gross topological com-parison, IgNAR V (Fig. 3A) is similar to aC1-type domain (Fig. 3D), which does nothave C and C� strands. However, as in con-ventional V-type domains, the IgNAR A-strand hydrogen bonds to both “top” and“bottom” sheets, by means of a bend atProN7. Strand A most resembles A strands inV� (Fig. 3B) and V� (Fig. 3C) domains by
Fig. 2. Crystal structure ofthe IgNAR-HEL complex. (A)Stereoview of the IgNAR Vdomain. Regions of hyper-variability are CDR1 andCDR3, as well as a shortstrand in place of the con-ventional CDR2 (termedHV2) and the region corre-sponding to HV4 in TCRs. Ig-NAR framework, light gray;CDR1, green; CDR3, yellow;HV2 region, magenta; HV4region, cyan. The two unusu-al disulfide bonds (orange)that constrain the CDR3 loopare between Cys residuesN35 to N92 and N97 toN104. (B) The IgNAR/HELcomplex. The HEL is shownin light blue and the IgNAR Vis colored as in (A). IgNARCDR3 residues ArgN100 andTyrN101 are deeply buried in the HEL active site. (C) The crystal structure of the HEL Asp523Ser52
mutant in complex with oligosaccharide [PDB accession code 1LSZ (27)] highlights the location of thelysozyme active site. The lysozyme is oriented as in (B).
R E P O R T S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1771
length (one residue shorter than V� and VH)and in the cis conformation of ProN7 (highlyconserved in V� domains). This structuralhomology with V� or V� domains reflects theprevious clustering of IgNAR V sequenceswith V regions of TCR and immunoglobulinL chains during the original phylogeneticanalysis (1).
With the exception of CDR H3, the CDRloops of human and murine antibodies gen-erally have “canonical” structures (30). How-ever, the IgNAR CDR1 loop does not closelyresemble human or murine canonical CDR1s(Fig. 3, A, B, and E) but instead converges onthe “type 4” CDR1 conformation found intwo camel VHH domains, cAb-Lys3 andcAb-RN05 (31) (figs. S1 and S2). This sim-
ilarity suggests that its conformation may beinfluenced by structural features and func-tional requirements specific to single-domainantibodies.
The IgNAR V region only contacts HEL bymeans of CDR1 and CDR3, with CDR3 resi-dues inserted directly into the HEL active-sitecleft (Figs. 2, B and C, and 4; tables S2 to S4).IgNAR ArgN100 forms a salt bridge with thecatalytic AspL52, which explains its partial in-hibition of HEL enzymatic activity (9) and lackof cross-reactivity with turkey egg-white ly-sozyme (26, 32). The molecular surface areaburied in the complex is extensive, consideringthat only two CDRs are used for antigen inter-action (33), with 666 and 734 Å2 of surfaceburied on IgNAR V and HEL, respectively (34).
A model was constructed of the IgNARtype II V domain, primarily on the basis ofthis type I V region structure (fig. S3) (35),which supports a proposed noncanonicaldisulfide between CDR3 and CDR1. Thetype II CDR3 would then adopt a moreextended conformation and protrude fromthe antibody framework akin to the camelidVHH AMD10 CDR3 (fig. S3). Both theIgNAR Type II model and AMD10 have anexposed lysine at the structurally equiva-lent positions 84 (IgNAR) or 96 (AMD10)(36) rather than a Gly, as in IgNAR Type Iand most other camelid VHH structures.Glycines at this position are not solventexposed, but instead are covered by thelong CDR3 that folds over and masks thishydrophobic surface (the VH/VL interface inconventional antibodies).
In a study of random IgNAR V cDNAs(5), a number of residues were identified ashaving either high (positive selection) or low(negative selection) ratios of replacement tosilent mutations. In addition to the CDR1 andCDR3 regions, residues in hypervariable re-gion 2 (HV2) (N45 to N51) were found to beunder strong positive selection (37). Theirhypermutation among different IgNAR V re-gions could be either because of the directrecognition of the antigen [as observed incamelid domains AMB7 and AMD10 (20)]or because they maintain and influence theconformation of the CDR3, which does di-rectly contact the antigen (supporting onlinematerial text).
Some species of shark respond readilyto foreign antigens with a potent IgNARresponse (9), and several libraries ofIgNAR V regions displayed in bacterio-phage have already been constructed (26,38, 39), which should facilitate engineeringof high affinity, minimal antigen-bindingdomains for biotechnological and biomed-ical use. The type I V region structure andtype II model presented here suggest thatthese single-domain shark antibodies cangenerate sufficient structural diversity torecognize a wide array of antigens by vary-ing the positions of their germline-encodedcysteines, which then markedly affect theconformation of CDR3 and the binding-sitearchitecture. Whether this single-domainantibody did indeed evolve from a primor-dial antigen-binding receptor or whether itwas derived later in phylogeny will remainunresolved until IgNAR (or IgNAR-like)molecules are found in more phylogeneti-cally distant vertebrates, such as the jaw-less vertebrates, lamprey (40, 41), andhagfish.
Note added in proof: While this paperwas in production, a paper reporting thestructures of the two unliganded type 2IgNAR variable domains was published(42).
Fig. 3. Comparison ofthe IgNAR V domainwith other immuno-globulin domains. (A)In IgNAR, the frontsheet consists ofstrands A, B, E, and D,whereas the back sheetconsists of strands A,G, F, and C. The bendbetween A and A issimilar to that seen inmost V� domains, witha cis-Pro residue at po-sition N7. (B) IgG V�domain from Fv B1-8(PDB accession code1A6V ). (C) TCR V� do-main from TCR KB5-C20 (PDB accessioncode 1KJ2). (D) IgG CLchain domain from Fab50.1 (PDB accessioncode 1GGB). (E) IgG VHdomain from Fab DB3(PDB accession code1DBB) (F) Camel VHHdomain from cAb-Lys3(PDB accession code1JTT) (27).
Fig. 4. Stereoview of the IgNAR V region/HEL interface. The main interactions of IgNAR HEL-5A7(gray) are from CDR3 (yellow) and CDR1 (green) with lysozyme (light blue). Waters are shown asred balls and disulfides in orange. Noninteracting portions of the HEL have been omitted for clarity.The residues with side chains depicted are those that make van der Waals contacts or hydrogenbonds in the complex. A, Ala; C, Cys; D, Asp; I, Ile; K, Lys; L, Leu; N, Asn; R, Arg; S, Ser; V, Val; W,Trp; and Y, Tyr.
R E P O R T S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1772
References and Notes1. A. S. Greenberg et al., Nature 374, 168 (1995).2. K. H. Roux et al., Proc. Natl. Acad. Sci. U.S.A. 95,
11804 (1998).3. M. H. Richards, J. L.Nelson, Mol. Biol. Evol. 17, 146 (2000).4. S. Muyldermans, T. Atarhouch, J. Saldanha, J. A. Bar-
bosa, R. Hamers, Protein Eng. 7, 1129 (1994).5. M. Diaz, R. L. Stanfield, A. S. Greenberg, M. F. Flajnik,
Immunogenetics 54, 501 (2002).6. K. R. Hinds, G. W. Litman, Nature 320, 546 (1986).7. F. Kokubu, R. Litman, M. J. Shamblott, K. Hinds, G.W.
Litman, EMBO J. 7, 3413 (1988).8. S. S. Lee, D. Fitch, M. F. Flajnik, E. Hsu, J. Exp. Med.
191, 1637 (2000).9. M. J. Flajnik, H. Dooley, unpublished data.
10. M. Diaz, M. F. Flajnik, Immunol. Rev. 162, 13 (1998).11. C. Hamers-Casterman et al., Nature 363, 446 (1993).12. A. Desmyter et al., Nature Struct. Biol. 3, 803 (1996).13. S. Spinelli et al., Nature Struct. Biol. 3, 752 (1996).14. K. Decanniere et al., Struct. Fold. Des. 7, 361 (1999).15. K. Decanniere, S. Muyldermans, L. Wyns, J. Mol. Biol.
300, 83 (2000).16. S. Spinelli et al., Biochemistry 39, 1217 (2000).17. S. Spinelli, M. Tegoni, L. Frenken, C. van Vliet, C.
Cambillau, J. Mol. Biol. 311, 123 (2001).18. A. Desmyter, K. Decanniere, S.Muyldermans, L.Wyns,
J. Biol. Chem. 276, 26285 (2001).19. K. Decanniere et al., J. Mol. Biol. 313, 473 (2001).20. A. Desmyter et al., J. Biol. Chem. 277, 23645 (2002).21. W. Vranken et al., Biochemistry 41, 8570 (2002).22. R. Loris et al., J. Biol. Chem. 278, 28252 (2003).23. M. Dumoulin et al., Nature 424, 783 (2003).24. Camel and llama VHH domains share about 65%
sequence identity with mouse and human VH do-mains; however, several mutations in the canonicalVH interface region render the camelid VHH domainsmore soluble than isolated human or murine VHdomains. Additionally, the long CDR3s in several ofthe camelid VHH domains are folded back across thisinterface region, partially rescuing it from solventexposure. The camelid CDR3 is sometimes anchoredto the immunoglobulin core by formation of a disul-fide bridge between CDR3 and CDR1 or FR2. Further-more, some camelid VHH domains can access re-cessed cavities, such as the HEL active-site cleft, bymeans of long CDR3 loops (12).
25. J. Davies, L. Riechmann, FEBS Lett. 339, 285 (1994).26. H. Dooley, M. F. Flajnik, A. J. Porter, Mol. Immunol.
40, 25 (2003).27. Materials and methods are available as supporting
material on Science Online.28. The IgNAR CDR3 is 20 residues in length, spanningN84 to N103 (Gly-Leu-Gly-Val-Ala-Gly-Gly-Tyr-Cys-Asp-Tyr-Ala-Leu-Cys-Ser-Ser-Arg-Tyr-Ala-Glu).
29. Comparison of the IgNAR V domain structure withother antibody x-ray structures with the programs Daliand SSM (27) reveals similar root mean square devia-tions for the IgNAR V domain from V�, VL, and VHdomains of around 0.7 to 1.0 Å for 45 core C� atoms.
30. C. Chothia, A. M. Lesk, J. Mol. Biol. 196, 901 (1987).31. The IgNAR CDR1 has root mean square deviations
from the cAb-Lys3 and cAb-RN05 CDR1s of 1.2 and1.5 Å, respectively, for 15 C� atoms (IgNAR residuesN22 to N36).
32. Of the seven residues that differ between HEL andturkey egg-white lysozyme, two (Arg733Lys73 andAsp1013Gly101) are found in the IgNAR-HEL interface.ArgL73 makes six van derWaals contacts, one hydrogenbond, and one salt bridge, and AspL101 makes 17 van derWaals contacts and five hydrogen bonds in the interfacewith IgNAR. The camelid VHH cAb-Lys3 also binds anepitope encompassing the recessed HEL active site,similarly using its CDR3 for access (12). Several murineantibodies to lysozyme (HyHEL10, HyHEL8, HyHEL26,and HyHEL63) recognize a common epitope around theactive site, but do not penetrate this site as deeply as docAb-Lys3 and IgNAR.
33. The camelid anti–ribonuclease A VHH domain cAb-RN05 uses only CDR1 and CDR3 for binding antigen,whereas the camelid anticarbonic anhydrase VHHdomain cAb-CA05 uses CDR3 almost exclusively withonly two van derWaals contacts to the antigen fromCDR1. Similarly, the camelid anti–�-amylase VHHdomains AMB7 and AMD10 use all three CDR loops,
but CDR1 contributes only 5% of the total buriedsurface area on the antibody upon antigen binding.
34. The IgNAR-lysozyme interface is comparable in sizeto those seen in lysozyme-Fab (Fv) complexes thatrange from 538 to 829 Å2 for the Fab and 540 to 831Å2 for the lysozyme (table S3). Similar interface sizeshave also been observed for lysozyme complexeswith camel VHH domains. A total of 122 van derWaals contacts (table S2), eight hydrogen bonds, andthree charged interactions are made between HELand the IgNAR (table S4). The majority of the buriedsurface on the IgNAR V domain is contributed byCDR3 residues N85 to N89, N91, N93, N95 to N96,and N98 to N103 (75%), with the remainder byCDR1 N26 to N33 (Fig. 4). The HEL-IgNAR V regioninterface has a good shape-complementarity index of0.70 (0.72 and 0.70 for crystal form 2) (27), withwaters filling several cavities in the interface (fig. S4).A total of 14 water molecules contact both theIgNAR V domain and HEL, with 7 of these (waters 2,4, 7, 8, 60, 114, and 266) sequestered from contactwith external solvent.
35. Type I and type II sequences are 90% identical.IgNAR type II V domains have only four conservedcysteines, rather than the six or more found in typeI, and tend toward smaller CDR3 lengths [9 to 18amino acids (26)].
36. The structurally equivalent positions LysN84 (IgNAR)or Lys96 (AMD10) correspond to positions Leu89 orHis93 of conventional V domains.
37. IgNAR residues AsnN45, GluN46, SerN48, SerN50,LysN51, GlyN62, SerN63, and LysN64 are under strongpositive selection.
38. S. D. Nuttall et al., Mol. Immunol. 38, 313 (2001).
39. S. D. Nuttall et al., FEBS Lett. 516, 80 (2002).40. Unexpectedly, a set of receptors (variable lympho-
cyte receptors) that may modulate immune recogni-tion in lamprey has recently been identified. Thesereceptors are arranged from leucine-rich repeats andmay constitute a component of a primitive immunesystem in lampreys (41).
41. Z. Pancer et al., Nature 430, 174 (2004).42. V. A. Streltsov et al., Proc. Natl. Acad. Sci. U.S.A. 101,
12444 (2004).43. We thank P. Horton for technical assistance. I. Hol-
ton, G. Meigs, the staff of Advanced Light SourceBeamline 8.3.1 for support during data collection, andThe National Aquarium in Baltimore for meticulouscare of the sharks. Supported by NIH grants GM38273(R.L.S. and I.A.W.) and RR06603 (H.D. andM.F.F.). Thisis manuscript no. 16602-MB from The Scripps Re-search Institute. The coordinates and structure fac-tors have been deposited in the Protein Data Bank(PDB) with accession codes 1SQ2 (crystal form 1)and 1T6V (crystal form 2).
Supporting Online Materialwww.sciencemag.org/cgi/content/full/1101148/DC1Materials and MethodsSOM TextFigs. S1 to S4Tables S1 to S4References and Notes
7 June 2004; accepted 4 August 2004Published 19 August 2004;10.1126/science.1101148Include this information when citing this paper.
Defining a Link with Asthmain Mice Congenitally Deficient
in EosinophilsJames J. Lee,1,2* Dawn Dimina,1,2 MiMi P. Macias,1,2†
Sergei I. Ochkur,1,2 Michael P. McGarry,1,2 Katie R. O’Neill,2,3
Cheryl Protheroe,2,3 Ralph Pero,2,3 Thanh Nguyen,1,2
Stephania A. Cormier,1,2‡ Elizabeth Lenkiewicz,1,2
Dana Colbert,2,3 Lisa Rinaldi,4 Steven J. Ackerman,5
Charles G. Irvin,4 Nancy A. Lee2,3*
Eosinophils are often dominant inflammatory cells present in the lungs ofasthma patients. Nonetheless, the role of these leukocytes remains poorlyunderstood. We have created a transgenic line of mice (PHIL) that are specif-ically devoid of eosinophils, but otherwise have a full complement of hema-topoietically derived cells. Allergen challenge of PHIL mice demonstrated thateosinophils were required for pulmonary mucus accumulation and the airwayhyperresponsiveness associated with asthma. The development of an eosino-phil-less mouse now permits an unambiguous assessment of a number ofhuman diseases that have been linked to this granulocyte, including allergicdiseases, parasite infections, and tumorigenesis.
The underlying features of asthma display amarked heterogeneity (1, 2), yet the presence ofeosinophils in the airway lumen and lung tissuehas been recognized even in the earliest studies(3) and is often regarded as a defining feature ofthis disease (4, 5). Moreover, the recruitment ofeosinophils occurs in animal models of aller-gen-mediated respiratory inflammation; in par-ticular, mouse models have offered unique op-portunities with which to examine detailedpathologic features of this disease. However,
the availability of clinical studies and numerousmouse models of asthma have not led to anunambiguous description of eosinophil ef-fector functions in asthma, and questionsremain as to the specific role(s), if any, ofthese leukocytes (6).
A line of mice devoid of eosinophils wascreated to test hypotheses that link eosinophilsand asthma-related pathogenesis. Transgenicmice devoid of eosinophils were created by lin-eage-specific expression of a cytocidal protein
R E P O R T S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1773
with a promoter fragment identified from studiesof secondary granule protein genes expressed inmouse eosinophils (7–11). A candidate promoterfrom the gene for eosinophil peroxidase (EPO)was selected on the basis of transfection studieswith EPO promoter–luciferase reporter con-structs in the eosinophilic cell line AML14.3D10
(12). These studies revealed that upstream se-quences from the mouse EPO gene were capableof supporting high-level expression that wasunique to eosinophil lineage–committed cells(fig. S1). In addition to mouse EPO-derivedsequences, the transgenic construct developedincluded the diphtheria toxin A (DTA) chain
open reading frame (13). The cytocidal charac-ter of diphtheria toxin is mediated by the DTAchain (the B chain provides entry into eukary-otic cells) through the catalytic degradation ofelongation factor-2 and the subsequent col-lapse of protein synthesis (14).
Assessment of circulating leukocytes (15) inthe resulting EPO-DTA transgenic (PHIL) micedemonstrated that these animals were devoid ofeosinophils but otherwise have a full comple-ment of hematopoietically derived cells (Fig.1A). An examination of splenic lymphoid cells(15) revealed normal numbers of B cells, T cells,and the T lymphocyte CD4� and CD8� sub-types (Fig. 1B). Assessments of lung sectionsand peritoneal cavity exudates from PHIL micerevealed wild-type levels of mast cells (fig. S2,A and B). Moreover, circulating basophils wereidentified in peripheral blood from PHIL mice(fig. S2C), demonstrating that even a leukocytelineage sharing a direct common precursor withthe eosinophil lineage was unaffected. The spe-cific ablation of eosinophils in PHIL mice alsooccurred with no effects on either erythropoiesisor the production of platelets (Fig. 1C). A nom-inal elevation of total white blood cell countswas consistently observed in PHIL mice relativeto negative littermates. This increase, however,was not specific to any one cell type and did notelevate circulating cell numbers beyond the nor-mal observable range in wild-type mice.
The loss of eosinophils in PHIL mice wasnearly absolute, with only an occasional eosino-phil identified in surveys of blood films from 1of 20 animals examined. This eosinophil defi-ciency is lifelong and a Mendelian inheritabletrait of the line. The specificity of the eosinophildeficiency in PHIL mice was achieved through across with interleukin (IL)–5 transgenic animals(16). These IL-5 transgenic mice have circulat-ing eosinophil levels that, in some cases, exceed100,000 per mm3 of blood, representing �50%of all white blood cells. Analyses of blood fromdouble transgenic animals (i.e., mice carryingboth the DTA and IL-5 transgenes) again revealeda complete absence of eosinophils (Fig. 1D).
The eosinophil-deficient character ofPHIL mice was extended further by immu-nohistochemistry with antibodies specific forMajor Basic Protein (MBP) (15, 17, 18).Tissues with abundant resident populations ofeosinophils (i.e., bone marrow, uterus, small
1Division of Pulmonary Medicine, 2Department ofBiochemistry and Molecular Biology, 3Division ofHematology/Oncology, Mayo Clinic Arizona,Scottsdale, AZ 85259, USA. 4Vermont Lung Center,Department of Medicine, University of Vermont,Burlington, VT 05405, USA. 5Department of Bio-chemistry and Molecular Biology, University of Il-linois, College of Medicine, Chicago, IL 60612, USA.
*To whom correspondence should be addressed. E-mail:[email protected] (J.J.L.) and [email protected] (N.A.L.)†Present address: The EAR Foundation of Arizona,Phoenix, AZ 85008, USA.‡Present address: Department of Biology, LouisianaState University, Baton Rouge, LA 70803, USA.
Fig. 1. The eosinophil deficiency of PHIL mice is specific and definitive. (A) Peripheral blood of PHILmice is devoid of eosinophils without effects on the composition of other leukocytes (mean � SE,n � 17 animals per group). (B) The targeted loss of eosinophils had no effects on lymphocytesubtypes (n� 5 animals per group). (C) The specific ablation of eosinophil lineage–committed cellshad no additional effects on other hematopoietic parameters, although a nonspecific marginalincrease in the steady-state levels of total circulating white blood cells was observed. (D)Fluorescence-activated cell sorting analyses demonstrated that the marked blood eosinophilia (i.e.,the presence of CCR3� cells) of the IL-5 transgenic line NJ.1726 (16) was completely abolished inNJ.1726/PHIL double transgenic mice. PE, phycoerythrin. (E) Immunohistochemistry (dark purple–stained cells) with eosinophil-specific rabbit polyclonal antisera to MBP demonstrates that tissuesor organs with prominent resident populations of eosinophils at baseline in wild-type mice weredevoid of these granulocytes in PHIL mice. Scale bar, 100 m.
R E P O R T S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1774
intestines, and thymus) in wild-type animalswere shown to be devoid of these granulo-cytes in PHIL mice (Fig. 1E).
PHIL mice were subjected to an acute aller-gen sensitization/aerosol challenge model ofasthma (15) to determine if the presence ofeosinophils was causatively linked to the devel-opment of disease symptoms. Whereas wild-type mice sensitized/aerosol challenged withchicken ovalbumin (OVA) developed a signifi-cant airway eosinophilia [�50% of bronchoal-veolar lavage fluid (BAL) cells], PHIL micewere essentially devoid of eosinophils, with onlytrace numbers (�0.5%) of eosinophils identifi-able in the BAL of one of four OVA-treatedanimals (Fig. 2A). The loss of eosinophils fromthe lungs of OVA-treated PHIL mice also ex-tended to tissue-infiltrating cells. Specifically,the lungs of OVA-treated PHIL mice were de-void of eosinophils, unlike the significant tissueeosinophilia that occurred in the areas surround-ing the central airways (peribronchial) and thevasculature (perivascular) of OVA-treated wild-type animals (Fig. 2, B to D, and fig. S3).Examination of blood films and bone marrowsmears from OVA-treated PHIL animals againrevealed only an occasional eosinophil in afraction of the animals examined.
The targeted ablation of eosinophils had sig-nificant effects on allergen-induced pulmonarypathology, suggesting a causative role for thesegranulocytes. Overall, OVA-induced histopa-thology in PHIL mice was attenuated relative toOVA-treated wild-type littermates. This lack ofpathology was manifested by the reduced airwayepithelial hypertrophy in OVA-treated PHILmice (Fig. 2, B and C). In addition, assessmentof airway mucins by periodic acid–Schiff (PAS)staining (15) demonstrated that OVA-inducedgoblet cell metaplasia/mucus accumulation(GM/MA) in PHIL mice was significantly re-duced (Fig. 3, A to C). A quantitative assessmentof the staining in these tissue sections revealed a68% reduction of PAS staining in PHIL micerelative to OVA-treated wild-type animals (Fig.3D). However, the GM/MA observed in OVA-treated PHIL mice was still significant whencompared to allergen-naive animals. This obser-vation suggests that eosinophils contribute to,and are necessary for, the levels of pathologyobserved in wild-type mice, but that they are notalone sufficient to account for these wild-typelevels. That is, both eosinophil-dependent and-independent mechanisms exist in the lung thatelicit GM/MA after allergen challenge.
The association between allergen-inducedpulmonary eosinophilia and the development oflung dysfunction in both asthma patients andmouse models has been, at best, a collection ofconfusing and often contradictory observations.The lack of symptom improvement in asthmapatients after administration of antibodies to IL-5exemplifies the ambiguous character of clinicalstudies that attempt to ablate eosinophils (6).Mouse models purporting to ablate eosinophils
Fig. 2. The pulmonary eosinophilia associated with OVA sensitization/aerosol challenge was abolishedin PHIL mice. (A)OVA-induced eosinophilia of the airway lumen was lost (decreased by �99%) in PHILmice (mean � SE, n � 5 animals per group). *, P � 0.001. (B and C) Assessments of infiltratingeosinophils in (B) wild-type and (C) PHIL mice by immunohistochemistry (dark purple–stained cells)with rabbit polyclonal antisera to mouse MBP revealed that OVA-induced accumulation of eosinophilswas also extinguished in PHIL mice. Scale bar, 100 m. (D) Quantitative assessments of the number ofeosinophils infiltrating peribronchial areas (i.e., eosinophils per mm2) demonstrated that OVA-treatedPHIL mice were devoid of tissue eosinophils (mean � SE, n � 5 animals per group). Ø indicates theabsence of eosinophils in any of the sections of any of the mice in the cohort examined.
Fig. 3. The specific loss of eosinophils in PHIL mice resulted in a significant reduction in OVA-inducedGM/MA. Representative lung sections after PAS staining are shown for (A) saline control and (B) OVAsensitized/OVA aerosol challenged wild-type mice in comparison to (C) OVA sensitized/OVA aerosolchallenged PHIL mice. The sections of each panel show early-branching central conducting airways,whereas the insets show smaller, more distal bronchioles. Scale bars, 100 m. (D) Quantitativeassessments of airway epithelial mucus content showed a marked decrease (relative to wild type) inPHIL mice (mean � SE, 5 to 10 animals per group). All evaluations of histopathology were performedin duplicate as independent observer-blinded assessments. *, P � 0.05.
R E P O R T S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1775
are also ambiguous, as they either do not com-pletely eliminate pulmonary eosinophils or theyelicit the loss of eosinophils by mechanisms thatdo not differentiate between effects on eosino-phils and other potentially important cellulartargets (19–22). However, measurements of lungfunction after OVA sensitization/aerosol chal-lenge of PHIL mice (15) showed that methacho-line-induced airway hyperresponsiveness wasdependent on the presence of eosinophils (Fig.4). Moreover, the specific loss of eosinophilsalso led to improvement of other pulmonaryfunction parameters associated with the distalregions of the lung (fig. S4).
The lack of observable phenotypes in knock-out mice deficient for the abundant secondarygranule proteins MBP-1 (18) and EPO (17)suggests that activities other than degranulation,including antigen presentation (23), the releaseof small molecule mediators of inflammation[e.g., the synthesis and release of eicosanoidmediators of inflammation (24)], and immuneregulation of the pulmonary microenvironmentthrough either modulations of T cell activities(21) or eosinophil-derived cytokine and/or che-mokine expression (25) are likely to be therelevant effector functions. Eosinophil-derivedcytokine and/or chemokine expression, in partic-ular, is noteworthy as it may account for thechronic and seemingly self-sustaining characterof allergic pulmonary inflammation, which oftenleads to lung remodeling events (26, 27). Signif-icant decreases of Th2 cytokine levels in BAL ofOVA-treated PHIL mice (28) lend support tothis hypothesis and suggest that a prominenteosinophil effector function in the lung is local-ized immune regulation.
This study shows that eosinophil activitiesare important contributory factors leading to
symptoms that are classically defined as hall-mark features of asthma. More importantly,these data provide validation of earlier studiesthat independently concluded that a causativelink exists between eosinophils and allergic pul-monary pathologies (22, 29). The dependency ofallergen-induced pulmonary pathologies on eo-sinophils suggests that these granulocytes partic-ipate at a significant level in underlying inflam-matory responses. Regardless of the ultimatedefinition of the causative activities mediated byeosinophils, the challenge of future studies willbe to develop confirmatory clinical studies tounambiguously define the role(s) and extent ofeosinophil effector functions in asthma patients.The results of such studies will not only widenour understanding of the principle causes ofasthma, but are also likely to lead to targetedtherapeutic approaches previously dismissedand/or overlooked.
References and Notes1. P. O’Byrne, J. Allergy Clin. Immunol. 102, S85 (1998).2. W.W. Busse, R. F. Lemanske Jr., N. Engl. J. Med. 344,
350 (2001).3. H. L. Huber, K. K. Koessler, Arch. Intern. Med. 30, 689
(1922).4. J. Bousquet et al., N. Engl. J. Med. 323, 1033 (1990).5. W. W. Busse, W. F. Calhoun, J. D. Sedgwick, Am. Rev.Respir. Dis. 147, S20 (1993).
6. M. J. Leckie et al., Lancet 356, 2144 (2000).7. K. A. Larson et al., J. Immunol. 155, 3002 (1995).8. M. P. Macias et al., J. Leukoc. Biol. 67, 567 (2000).9. S. A. Cormier et al., Mamm. Genome 12, 352 (2001).
10. K. A. Larson et al., Proc. Natl. Acad. Sci. U.S.A. 93,12370 (1996).
11. M. A. Horton, K. A. Larson, J. J. Lee, N. A. Lee,J. Leukoc. Biol. 60, 285 (1996).
12. C. C. Paul et al., J. Leukoc. Biol. 56, 74 (1994).
13. R. D. Palmiter et al., Cell 50, 435 (1987).14. R. J. Collier, Toxicon 39, 1793 (2001).15. Materials and methods are available as supporting
material on Science Online.16. J. J. Lee et al., J. Exp. Med. 185, 2143 (1997).17. K. L. Denzler et al., J. Immunol. 167, 1672 (2001).18. K. L. Denzler et al., J. Immunol. 165, 5509 (2000).19. W. Henderson et al., J. Clin. Invest. 100, 3083 (1997).20. S. P. Hogan et al., J. Immunol. 161, 1501 (1998).21. J. Mattes et al., J. Exp. Med. 195, 1433 (2002).22. J. P. Justice et al., Am. J. Physiol. Lung Cell. Mol.
Physiol. 284, L169 (2003).23. H. Z. Shi, A. Humbles, C. Gerard, Z. Jin, P. F. Weller,
J. Clin. Invest. 105, 945 (2000).24. C. G. Irvin, Y. P. Tu, J. R. Sheller, C. D. Funk, Am. J.
Physiol. 272, L1053 (1997).25. J. P. Justice et al., Am. J. Physiol. LCMP 282, L302
(2002).26. J. Y. Cho et al., J. Clin. Invest. 113, 551 (2004).27. P. Flood-Page et al., J. Clin. Invest. 112, 1029 (2003).28. S. I. Ochkur, G. Cieslewicz, J. J. Lee, N. A. Lee, in
preparation.29. H. H. Shen et al., J. Immunol. 170, 3296 (2003).30. We wish to acknowledge the kind gift of the gene
encoding DTA by I. Maxwell.We also thank the MayoClinic Arizona Core Facilities (L. Barbarisi, T. Brehm-Gibson, S. Savarirayan, M. Ruona, B. Schimeck, J.Caplette, and J. Protheroe) and our administrativestaff (L. Mardel, J. Ford, and P. McGarry). Supportedby the Mayo Foundation; an American Heart Associ-ation grant to J.J.L. (no. 045580Z ); grants from NIHto J.J.L. (no. HL065228), N.A.L. (no. HL058723), S.J.A.(nos. AI033043 and AI025230), and C.G.I. (nos.NCRR-COBRE P20RR15557, P01-HL67004, and HL-EB67273); and by NIH postdoctoral fellowships toMM.P.M. (no. HL10105) and S.A.C. (no. AR08545).
Supporting Online Materialwww.sciencemag.org/cgi/content/full/305/5691/1773/DC1Materials and MethodsFigs. S1 to S4References and Notes
22 April 2004; accepted 23 July 2004
A Critical Role for Eosinophils inAllergic Airways Remodeling
Alison A. Humbles,1*† Clare M. Lloyd,2*† Sarah J. McMillan,2
Daniel S. Friend,3 Georgina Xanthou,2 Erin. E. McKenna,1 SorinaGhiran,1 Norma P. Gerard,1 Channing Yu,4 Stuart H. Orkin,5
Craig Gerard1
Features of chronic asthma include airway hyperresponsiveness, inflammatoryinfiltrates, and structural changes in the airways, termed remodeling. The contri-bution of eosinophils, cells associated with asthma and allergy, remains to beestablished. We show that in mice with a total ablation of the eosinophil lineage,increases in airway hyperresponsiveness and mucus secretion were similar to thoseobserved in wild-type mice, but eosinophil-deficient mice were significantly pro-tected from peribronchiolar collagen deposition and increases in airway smoothmuscle. These data suggest that eosinophils contribute substantially to airwayremodeling but are not obligatory for allergen-induced lung dysfunction, andsupport an important role for eosinophil-targeted therapies in chronic asthma.
Since its discovery by Paul Erlich in 1879,there has been a wealth of information doc-umenting the association between eosinophilsand parasitic or allergic diseases (1). The roleof eosinophils in allergic disease remainscontroversial. Although T helper cell 2 (TH2)lymphocytes are thought to drive asthmatic
responses, increasing evidence suggests thateosinophils are associated with developmentof lung dysfunction and subsequent immuno-pathology (2–4).
Asthma is a chronic disease characterizedby airway hyperresponsiveness (AHR), air-way inflammation, and reversible airway ob-
Fig. 4. In the absence of eosinophils, OVA-induced airway hyperresponsiveness does notdevelop. Lung function was assessed as airwayresistance (Rn) in response to aerosolizedmethacholine, in saline-treated (WT/Saline)and OVA sensitized/OVA aerosol challenged(WT/OVA) wild-type mice in comparison tosaline-treated (PHIL/Saline) and OVA sensi-tized/OVA aerosol challenged (PHIL/OVA) PHILmice (n � 5 to 10 animals per group). Asterisksindicate a significant difference (P � 0.01) be-tween WT/OVA and either WT/Saline, PHIL/Saline, or PHIL/OVA mice.
R E P O R T S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1776
struction. In addition, structural changes inthe airway, termed remodeling, occur as aresult of an imbalance in tissue regenerationand repair mechanisms (5, 6). Subepithelialfibrosis is a distinctive feature of airway re-modeling and contributes to the thickenedairway walls due to the deposition of collagentypes I, III, and IV, fibronectin, and otherextracellular matrix (ECM) proteins such astenascin and laminin (7, 8). Increased airwaysmooth muscle (ASM) mass and excessivemucus secretion from hyperplastic gobletcells are also features of airway remodeling(9, 10).
To define the role of eosinophils in asth-ma pathophysiology, we used the recentlydescribed eosinophil lineage–ablated line,�dbl GATA mice (11). Deletion of a high-affinity GATA site in the GATA-1 promotorresults in a complete ablation of the eosino-phil lineage without affecting the develop-ment of the other GATA-1–dependent lin-eages (erythroid, megakaryocytic, and mastcell) (11).
We examined the extent of this mutation oneosinophil recruitment following acute andchronic allergen challenge in a murine model ofallergic airways disease (12, 13). Histologicalexamination confirmed that sham-treated �dblGATA mice were completely devoid of eosin-ophils and that allergen challenge failed to in-duce eosinophilia in the airways and bone mar-row of �dbl GATA mice (Fig. 1, A to D).Eosinophil peroxidase (EPO) analysis (13) oflung tissue (fig S2) and bone marrow (Fig. 1E)confirmed the absence of eosinophils in thesetissues. During acute and chronic phases, wild-type (WT) mice showed significant increases inpulmonary eosinophils and lymphocytes. Aller-gen challenge induced similar numbers of alve-olar macrophages and lymphocytes in both WTand �dbl GATA mice, confirming that the �dblGATA mutation was selective for eosinophils[bronchoalveolar lavage (BAL) cell counts andlung EPO are shown in figs. S1 and S2)]. Giventhe role of GATA-1 in mast cell differentiation(14), histological analysis of chloroacetate es-terase–stained tissue sections demonstrated thatthis mutation had no effect on mast cell num-bers (15).
Airway function was assessed usingwhole-body plethysmography (13). Pulmo-nary conductance (GL) and compliance(Cdyn) (16), and Penh [a calculated value thatcorrelates with measurement of airway resis-tance, obstruction, and intrapleural pressurein the same mouse (17)] were assessed on day25 after acute challenge on days 21 to 24. WTallergen-challenged mice developed a signif-icantly enhanced response to methacholine(Mch) when compared to WT sham-treatedanimals. In the absence of eosinophils, aller-gen-challenged �dbl GATA mice displayedenhanced responses to Mch relative to base-line sham controls that were comparable tothose displayed by challenged WT mice (Fig.2, A and B). Similarly, the Penh responses ofovalbumin (OA)-challenged �dbl GATAmice to Mch were almost identical to those oftheir WT-challenged counterparts (fig. S3).During the chronic phase, mice were assessed
for changes in lung function weekly until day55. Although the enhancement following al-lergen challenge was lower than that seenduring the acute phase (at day 25), allergen-challenged WT and �dbl GATA mice dis-played similar enhanced responses to cholin-ergic stimulation relative to baseline shamcontrols (fig. S4). Thus, eosinophil deficien-cy conferred no protection against Mch-in-duced AHR (during acute and chronic aller-gen challenge), suggesting that eosinophilsare not obligatory for allergen-inducedchanges in airway physiology.
Given the role of TH2 cells in the allergicresponse, we examined TH2 cytokine expres-sion in the lungs of acute and chronicallychallenged WT and �dbl GATA mice. TH2responses in �dbl GATA mice appeared nor-mal and were similar to those of their WTlittermates. �dbl GATA mice displayed in-creased BAL and lung interleukin-4 (IL-4),
1Department of Pediatrics, Children’s Hospital, Har-vard Medical School, Boston, MA 02115, USA. 2Leu-kocyte Biology Section, Division of Biomedical Scienc-es, Faculty ofMedicine, Imperial College, London SW72AZ, UK. 3Department of Pathology, Brigham andWomen’s Hospital, Harvard Medical School, Boston,MA 02111, USA. 4Department ofMedicine,Massachu-setts General Hospital, Harvard Medical School, Bos-ton, MA 02114, USA. 5Department of Pediatric On-cology, Dana Farber Cancer Institute and Children’sHospital, Harvard Medical School and the HowardHughes Medical Institute, Boston, MA 02115, USA.
*These authors contributed equally to this work.†To whom correspondence should be addressed.E-mail: [email protected], [email protected]
Fig. 1. Acute allergen challenge induceseosinophil accumulation in the lung andbone marrow of WT (A and C) but not�dbl GATA mice (B and D). Originalmagnification, �20 m. (E) EPO analy-
sis of bone marrow confirmed that �dbl GATA mice (solid bars) are devoid of eosinophils comparedto WT controls (open bars) before (sham) and after (OA) allergen challenge. Results are means �SEM (Sham, n � 4 mice; OA, n � 5 mice). Significant differences between respective sham-treatedand sensitized/challenged WT or �dbl GATA mice are indicated as *P � 0.03 and **P � 0.008.
Fig. 2. AHR following acute allergen challenge. Sham-treated (dashed lines)WT (�) or �dbl GATAmice (�) mice were exposed to aerosolized saline, and OA-sensitized (solid lines)WT (e) and �dblGATA mice (f) were exposed to aerosolized OA on days 21 to 24. About 21 to 24 hours after thelast aerosol challenge, mice were anesthetized, intubated, and mechanically ventilated, and airwayresponses to increasing concentrations of intravenous Mch were assessed. The dose-responsecurves for (A) pulmonary conductance (GL) and (B) pulmonary compliance (Cdyn) are shown.Results are means � SEM (Sham, n � 4 mice; OA, n � 8 or 9 mice) of the percentage minimaldecrease in pulmonary conductance or compliance obtained after Mch challenge compared withthe baseline value just before challenge. Significant differences between respective sham-treatedand sensitized/challenged WT or �dbl GATA mice are indicated as *P � 0.05 to P � 0.01.
R E P O R T S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1777
IL-5, and IL-13 protein following acute aller-gen challenge. Likewise, IL-4 and IL-5 ex-pression during the chronic phase were com-parable for WT and �dbl GATA mice (fig.S5). Numbers of TH2 cells, determined bystaining lungs for the TH2 surface markerT1/ST2, were found to be comparable be-tween WT and �dbl GATA mice (15). More-over, serum-specific OA–immunoglobulinE was similar (acute OA WT � 3713 � 539ng/ml versus OA �dbl GATA mice �4059 � 789 ng/ml; chronic OA WT �5204 � 716 ng/ml versus OA �dbl GATAmice � 5635 � 741 ng/ml; n � 6 to 9mice). These data demonstrate that aller-gen-driven TH2 responses develop in theabsence of eosinophils.
TH2 cytokines (IL-4, IL-5, IL-9, and IL-13) and transforming growth factor–� (TGF-�) have been shown to induce subepithelialfibrosis (18–24). Recent reports support apotential role for eosinophils in the develop-ment of airway remodeling (2–4). Increasedeosinophils in the bronchial mucosa of severeasthmatics have been associated with base-ment membrane thickening (25), and eosino-phils are capable of secreting an array ofprofibrotic mediators (22, 23). However,studies in which IL-5 activity was inhibited,although associated with a decrease in eosin-ophil numbers, could theoretically be operat-ing on a number of pathways independent ofthe eosinophil (2–4). In light of this ambigu-ity, we examined the effects of specific eo-sinophil deficiency on airway remodeling fol-lowing chronic challenge.
Increased mucus secretion from hyperplastic
goblet cells, shown by periodic acid-Schiff(PAS)–positive cells in the bronchial epithelium(13), was similar in WT and �dbl GATA micecompared to sham controls after acute challenge,and these increases were sustained throughoutchronic challenge (fig. S6). Thus, enhanced mu-cus secretion occurs in allergic airways indepen-dent of eosinophils.
Increased subepithelial deposition ofECM proteins, specifically collagen, is aprominent feature of airway remodeling. Weexamined matrix deposition (collagen and fi-brin) in lung sections stained with Martiusscarlet blue (MSB) (13, 26). Sham miceshowed a thin uniform layer of matrix inperibronchiolar subepithelial regions (Fig. 3,A and B), whereas acute challenge marginal-ly increased fine matrix in both WT and �dblGATA mice within some infiltrates (15). Pro-longed challenge of WT mice significantlyincreased matrix deposition in the subepithe-lial layer of the bronchioles and perivascularregions. Dense fibrils were seen in the sub-epithelial and submucosal areas and in be-tween the inflammatory cells. In marked con-trast, matrix deposition in these same regionswas consistently reduced in �dbl GATAmice when compared with that in WT mice(Fig. 3, A to D; fig. S7, A to D). Quantitativeimage analysis of MSB-stained lung sectionsand biochemical measurement of total colla-gen in lung tissue (13) confirmed that pro-longed allergen challenge of WT mice pro-voked a marked increase (up to threefold) inmatrix deposition, as compared with that seenin sham mice, and levels were significantlyreduced in challenged �dbl GATA mice (Fig.
3, E and F, respectively). These results con-clusively demonstrate that eosinophils con-tribute to allergen-induced subepithelial col-lagen deposition.
The effects of eosinophil deficiency onASM hyperplasia and proliferation were deter-mined by counting the numbers of total andproliferating cell nuclear antigen (PCNA)–posi-tive smooth muscle cells along the basementmembrane of three or four bronchioles per an-imal (13). Prolonged allergen challenge of WTmice induced a significant increase in the totaland proliferating number of ASM cells com-pared with that seen in sham mice. This in-crease was absent from airways of chronicallychallenged �dbl GATA mice (Fig. 4 and fig.S8). Prolonged allergen challenge induces phe-notypic changes in ASM cells (27), whichcould conceivably induce secretion of a numberof growth factors, like TGF-�, which contributeto ECM formation. We investigated expressionof active TGF-�1 in WT and �dbl GATA miceand consistently found no differences in TGF-�1 expression between chronically challengedWT and �dbl GATA mice (either protein ormRNA). These data suggest that reduced sub-epithelial fibrosis in our model is independentof TGF-�1 expression.
Our work contrasts with a recent reportdemonstrating that IL-5–deficient mice areprotected from collagen deposition becauseof a reduction in TGF-�–positive eosinophils(4). We have previously shown that mononu-clear cells, presumably macrophages, and not
Fig. 3. In the absence of allergen challenge,WT (A) and�dbl GATA (B) mice exhibited minimal subepithelialMSB staining (blue). In contrast, chronic OA challengeinduced a significant increase inMSB staining (C), whichwas markedly reduced in challenged �dbl GATA mice (D). Data are representative of 8 to 12 miceper group; original magnifications, �40. (E) Image analysis ofMSB-stained lung sections from shamor chronically challenged WT (open bars) and �dbl GATA mice (solid bars) confirmed thatchallenged �dbl GATA mice were significantly protected from collagen deposition (**P � 0.0001).Results are means � SEM (n � 8 to 12 mice per group). Significance between Sham WT and OAWT is indicated (*P � 0.0001). (F) Lung collagen was measured in sham and chronically challenged�dbl GATA mice. Individual values and means (solid lines) for each group are shown (n � 10 to 16mice per group). Significant differences between Sham WT and OA WT, and between OA WT and�dbl GATA mice, are indicated as *P � 0.001 and **P � 0.003, respectively.
Fig. 4. Eosinophil deficiency protects againstincreases in ASM. (A) Number of ASM cells(round and elongated) and (B) proliferating(PCNA-positive) ASM cells along the basementmembrane of three or four bronchioles permouse were determined in sham and chroni-cally challenged WT (open bars) and �dblGATA mice (solid bars). Results are means �SEM for each group (Sham, n� 4mice;OA, n�6 mice). Significant difference between OAWTand �dbl GATA mice is indicated (*P � 0.004).
R E P O R T S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1778
eosinophils are the main secretors of TGF-�1protein during chronic challenge (12). Thereason for this disparity is unclear (4), butvariability in protocols may account for thedifferences seen in the cell source and expres-sion levels of TGF-�. A number of otherfactors have been demonstrated to be profi-brotic in the lung, notably the chemokineMCP-1, thrombin, endothelin-1, and plas-minogen activator inhibitor 1 (28). It is dif-ficult to link the presence of these factors toeosinophils specifically. However, the cystei-nyl leukotrienes have been shown to belinked to both profibrotic remodeling re-sponses and eosinophils (29, 30). In fact, theeosinophil may be a major source of leuko-trienes, often overlooked.
Of importance is that these animal studiesare in accordance with observations made inhumans. Mild asthmatic patients pretreatedwith IL-5–specific antibody exhibited signif-icant reduction in tenascin, lumican, and pro-collagen III (3). Our results independentlydemonstrate that eosinophils are in part re-sponsible for both collagen and smooth mus-cle changes in a chronic model of asthma.Further, although the contribution of eosino-phils to lung dysfunction has been controver-sial, we show here that eosinophils are notobligatory for airway physiology changes as-sociated with this disease. Taken together,these data provide a rationale for anti-eosin-ophil–based therapeutics in chronic allergicairways disease.
References and Notes1. G. J. Gleich, C. R. Adolphson, K. M. Leiferman, Annu.Rev. Med. 44, 85 (1993).
2. D. I. Blyth, T. F.Wharton, M. S. Pedrick, T. J. Savage, S.Sanjar, Am. J. Respir. Cell Mol. Biol. 23, 241 (2000).
3. P. Flood-Page et al., J. Clin. Invest. 112, 1029 (2003).4. J. Y. Cho et al., J. Clin. Invest. 13, 551 (2004).5. P. J. Jeffery, A. J. Wardlaw, F. C. Nelson, J. V. Collins,
A. B. Kay, Am. Rev. Respir. Dis. 140, 1745 (1989).6. J. Bousquet, P. K. Jeffery, W. W. Busse, M. Johnson,
A. M. Vignola, Am. J. Respir. Crit. Care Med. 161,1720 (2000).
7. J. A. Elias, Z. Zhu, G. Chupp, R. J. Homer, J. Clin. Invest.104, 1001 (1999).
8. W. Busse, J. Elias, D. Sheppard, S. Banks-Schlegel,Am. J. Respir. Crit. Care Med. 160, 1035 (1999).
9. C. E. Brewster et al., Am. J. Respir. Cell Mol. Biol. 3,507 (1990).
10. A. Wanner, Chest 97, 11S (1990).11. C. Yu et al., J. Exp. Med. 195, 1387 (2002).12. S. McMillan, C. M. Lloyd, Clin. Exp. Allergy 34, 1
(2004).13. Materials and methods are available as supporting
material on Science Online.14. A. R. Migliaccio et al., J. Exp. Med. 197, 281 (2003).15. A. A. Humbles et al., unpublished observations.16. T. R. Martin, N. P. Gerard, S. J. Galli, J. M. Drazen,
J. Appl. Physiol. 64, 2318 (1988).17. E. J. Hamelmann et al., Am. J. Respir. Crit. Care Med.
156, 766 (1997).18. J. A. Rankin et al., Proc. Natl. Acad. Sci. U.S.A. 93,
7821 (1996).19. J. J. Lee et al., J. Exp. Med. 185, 2143 (1997).20. U. A. Temann, G. P. Geba, J. A. Rankin, R. A. Flavell, J.
Exp. Med. 188, 1307 (1998).21. Z. Zhu et al., J. Clin. Invest. 103, 779 (1999).22. I. Ohno et al., Am. J. Respir. Cell Mol. Biol. 15, 404
(1996).
23. E. M. Minshall et al., Am. J. Respir. Cell Mol. Biol. 17,326 (1997).
24. A. M. Vignola et al., Am. J. Respir. Crit. Care Med.156, 591 (1997).
25. S. E.Wenzel et al., Am. J. Respir. Crit. Care Med. 160,1001 (1999).
26. A. C. Lendrum, J. Clin. Pathol. 15, 401 (1962).27. L. M. Moir et al., Am. J. Physiol. Lung Cell. Mol.
Physiol. 284, L148 (2003).28. H. A. Chapman, J. Clin. Invest. 113, 148 (2004).29. T. C. Beller et al., Proc. Natl. Acad. Sci. U.S.A. 101,
3047 (2004).30. C. Bandeira-Melo, P. F. Weller, Prostaglandins Leukot.
Essent. Fatty Acids, 69, 135. (2003).31. We thank J. Brewer for technical assistance and the
staff of Animal Resources Children’s Hospital foranimal care. This work was supported by the NIH(grants AI39759 and HL10463). C.M.L. and S.J.M.were supported by the Wellcome Trust (award057704) and G.X. by the European Molecular BiologyFoundation.
Supporting Online Materialwww.sciencemag.org/cgi/content/full/305/5691/1776/DC1Materials and MethodsFigs. S1 to S8References
13 May 2004; accepted 21 July 2004
Children Creating Core Properties ofLanguage: Evidence from an
Emerging Sign Language in NicaraguaAnn Senghas,1* Sotaro Kita,2 Aslı Ozyurek3,4,5
A new sign language has been created by deaf Nicaraguans over the past 25years, providing an opportunity to observe the inception of universal hallmarksof language. We found that in their initial creation of the language, childrenanalyzed complex events into basic elements and sequenced these elementsinto hierarchically structured expressions according to principles not observedin gestures accompanying speech in the surrounding language. Successive co-horts of learners extended this procedure, transforming Nicaraguan signingfrom its early gestural form into a linguistic system. We propose that this earlysegmentation and recombination reflect mechanisms with which children learn,and thereby perpetuate, language. Thus, children naturally possess learningabilities capable of giving language its fundamental structure.
Certain properties of language are so central tothe way languages operate, and so widely ob-served, that Hockett termed them “design fea-tures” of language (1). This study asks whetherthese properties can arise naturally as a productof language-learning mechanisms, even whenthey are not available in the surrounding lan-guage environment. We focus here on two par-ticular properties of language: discreteness andcombinatorial patterning. Every language con-sists of a finite set of recombinable parts. Thesebasic elements are perceived categorically, notcontinuously, and are organized in a principled,hierarchical fashion. For example, we have dis-crete sounds that are combined to form words,that are combined to form phrases, and thensentences, and so on. Even those aspects of theworld that are experienced as continuous and
holistic are represented with language that isdiscrete and combinatorial. Together, these prop-erties make it possible to generate an infinitenumber of expressions with a finite system. It isgenerally agreed that they are universal hall-marks of language, although their origin is thesubject of continued controversy (2–7).
Humans are capable of representationsthat lack these properties. For example, non-linguistic representations such as maps andpaintings derive their structure iconically,from their referent. That is, patterns in therepresentation correspond, part for part, topatterns in the thing represented. In this way,half a city map represents half a city. Unlikelanguage, such nonlinguistic representationsare typically analog and holistic.
The present study documents the emer-gence of discreteness and combinatorial pat-terning in a new language. Over the past 25years, a sign language has arisen within acommunity of deaf Nicaraguans who lackedexposure to a developed language. This situ-ation enables us to discover how fundamentallanguage properties emerge as the nonlin-guistic becomes linguistic.
Before the 1970s, deaf Nicaraguan childrenand adults had little contact with each other.Societal attitudes kept most deaf individuals athome, and the few schools and clinics available
1Department of Psychology, Barnard College of Co-lumbia University, 3009 Broadway, New York, NY10027, USA. 2Department of Experimental Psycholo-gy, University of Bristol, 8 Woodland Road, BristolBS8 1TN, UK. 3F. C. Donders Center for CognitiveNeuroimaging, Nijmegen University, Adelbertusplein1, 6525 EK Nijmegen, Netherlands. 4Max Planck In-stitute for Psycholinguistics, Wundtlaan 1, 6525 XDNijmegen, Netherlands. 5Department of Psychology,Koc University, Rumeli Feneri Yolu, 34450, Sariyer,Istanbul, Turkey.
*To whom correspondence should be addressed.E-mail: [email protected]
R E P O R T S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1779
served small numbers of children. Interviewswith former students reveal little evidence ofcontact with classmates outside school, or aftergraduation (8, 9). In this context, no sign lan-guage emerged, as evidenced by the lack oflanguage in today’s adults over the age of 45.
In such situations, deaf people will oftendevelop “home signs”: communication sys-tems built up out of common gestures, usedwith family members. Although not full lan-guages, home signs exhibit some of the rudi-ments of language (10, 11). The home signsystems developed by Nicaraguans appear tohave varied widely from one deaf person toanother in form and complexity (12).
This situation changed abruptly with theopening of an expanded elementary schoolfor special education in 1977, followed by avocational school in 1981, both in Managua.Deaf enrollment in the programs initiallycomprised about 50 students, growing tomore than 200 by 1981 and increasing grad-ually throughout the 1980s. For the first time,students continued their contact outsideschool hours, and by the mid-1980s deafadolescents were meeting regularly on theweekends (8). Although instruction in schoolwas conducted in Spanish (with minimal suc-cess), these first children began to develop anew, gestural system for communicating witheach other. The gestures soon expanded toform an early sign language (13, 14).Through continued use, both in and out ofschool, the growing language has beenpassed down and relearned naturally every
year since, as each new wave of childrenentered the community (15).
Today there are about 800 deaf signers ofNicaraguan Sign Language (NSL), rangingfrom 4 to 45 years of age. Previous researchon NSL has found that changes in its gram-mar first appear among preadolescent sign-ers, soon spreading to subsequent, youngerlearners, but not to adults (16). This pattern oftransmission, when combined with the rapidand recent expansion of NSL, has created anunusual language community in which themost fluent signers are the youngest, mostrecent learners. Consequently, much of thehistory of the language can be surveyed byperforming a series of observations, progress-ing from the older signers, who retain muchof NSL’s early nature, to younger, more re-cent learners, who produce the language in itsexpanded, most developed form.
Following this logic, the present studycompares the signed expressions of 30 deafNicaraguans, grouped into cohorts accordingto the year that they were first exposed toNSL: 10 from a first cohort (before 1984), 10from a second cohort (1984 to 1993), and 10from a third cohort (after 1993). All of thedeaf participants have been signing NSLsince the age of 6 or younger. Their signedexpressions are compared to the gestures pro-duced by 10 hearing Nicaraguan Spanishspeakers while speaking Spanish (17).
In particular, we examine the gestures andsigns in expressions that describe complex mo-tion events, such as rolling down a hill or climb-
ing up a wall. We chose descriptions of motionfor two reasons. First, previous research hasfound that when speakers describe motionevents, they often produce co-speech gesturesthat iconically represent the movement (18, 19).Such gestures (unlike speech) are fully availableto deaf observers, likely providing raw materialsto shape into a sign language. Second, the de-scription of motion offers a promising domainfor detecting the introduction of segmented, lin-ear, and hierarchical organization of informationinto a communication system. Motion eventsinclude a manner of movement (such as rolling)and a path of movement (such as descending).These characteristics of motion are simultaneousaspects of a single event and are experiencedholistically. The most direct way to iconicallyrepresent such an event would be to representmanner and path simultaneously. Languages, incontrast, typically encode manner and path inseparate elements, combined according to therules of the particular language (20). For exam-ple, English produces one word to express man-ner (rolling) and another to express path (down),and assembles them into the sequence “rollingdown.” Signing that dissects motion events intoseparate manner and path elements, and assem-bles them into a sequence, would exhibit thesegmentation and linearization typical of devel-oped languages and unlike the experience ofmotion itself.
To collect samples of signing and gesturingthat describe motion events, we presented par-ticipants with an animated cartoon and video-taped them telling its story to a peer. Deafsubjects signed their narratives. Hearing sub-jects spoke Spanish, and only their co-speechgestures were analyzed. Those expressions thatincluded both manner and path informationwere coded with respect to how the informationwas integrated: (i) simultaneously, as a singlehand movement, and/or (ii) sequentially, artic-ulated separately within a string of simple man-ner-only and path-only elements (Fig. 1). Notethat a single multigesture expression can in-clude both means of integration.
Two analyses compared, across groups, theuse of each method of integration. Figure 2Ashows the proportion of the expressions pro-duced by each participant that include mannerand path simultaneously. All of the Spanishspeakers’ gestures (1.0) and most of the first-cohort signers’ expressions (0.73) use this ap-proach. Second- and third-cohort signers pro-duce relatively fewer expressions of this type(0.32 and 0.38). Figure 2B shows the proportionof expressions produced by each participant thatarticulate manner and path sequentially. Suchsequences are never observed in the Spanishspeakers’ gestures (0). First-cohort signers some-times include such sequences (0.27); second-and third-cohort signers include such sequencesin most of their expressions (0.78 and 0.73).
In appearance, the signs very much re-sembled the gestures that accompany speech.
Fig. 1. Examples of motionevent expressions from par-ticipants’ narratives. (A)Manner and path expressedsimultaneously. This exam-ple shows a Spanish speakerdescribing an event in whicha cat, having swallowed abowling ball, proceeds rapid-ly down a steep street in awobbling, rolling manner.The gesture shown here nat-urally accompanies hisspeech. Here, manner (wig-gling) and path (trajectoryto the speaker’s right) areexpressed together in a sin-gle holistic movement. (B)Manner and path expressedsequentially. This exampleshows a third-cohort signerdescribing the same rollingevent in Nicaraguan SignLanguage. Here, manner(circling) and path (trajecto-ry to signer’s right) are ex-pressed in two separatesigns, assembled into a se-quence. (The video clipsfrom which the frames weredrawn can be viewed at Sci-ence Online.)
R E P O R T S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1780
The movements of the hands and body in thesign language are clearly derived from a ges-tural source. Nonetheless, the analyses reveala qualitative difference between gesturingand signing. In gesture, manner and pathwere integrated by expressing them simulta-neously and holistically, the way they occurin the motion itself. Despite this analog, ho-listic nature of the gesturing that surroundedthem, the first cohort of children, who startedbuilding NSL in the late 1970s, evidentlyintroduced the possibility of dissecting outmanner and path and assembling them into asequence of elemental units. As second andthird cohorts learned the language in the mid-1980s and 1990s, they rapidly made this seg-mented, sequenced construction the preferredmeans of expressing motion events. NSL thusquickly acquired the discrete, combinatorialnature that is a hallmark of language.
Note that this change to the language, inthe short term, entails a loss of information.When representations express manner andpath separately, it is no longer iconically clearthat the two aspects of movement occurredsimultaneously, within a single event. Forexample, roll followed by downward mighthave instead referred to two separate events,meaning “rolling, then descending.”
However, the communicative power gainedby combining elements more than offsets thispotential for ambiguity. Elements and sequenc-ing provide the building blocks for linguisticconstructions (such as phrases and sentences)whose structure assigns meaning beyond thesimple sum of the individual words. We ob-served one such structured sequence pattern thathas emerged specifically for expressing simulta-neity. A sign can be produced before and afteranother sign or phrase in an A-B-A construction,essentially embedding the second element withinthe first, yielding expressions such as roll de-scend roll. This string can serve as a structuralunit within a larger expression like cat [rolldescend roll], or can even be embedded withinanother sign, as in waddle [roll descend roll]waddle, and so on. These A-B-A constructionsappeared in about one-third of the coded expres-sions (0.37) by participants from all three co-horts: four first-cohort signers, seven second-cohort signers, and six third-cohort signers. Theywere used to link various simultaneous aspectsof events, including agent and action (cat climbcat), ground and action (climb pipe climb), andmanner and path (roll descend roll). We ob-served 15 examples of these constructions ap-plied specifically for combining manner andpath information, again by signers of all threecohorts: two first-cohort signers, four second-cohort signers, and four third-cohort signers.They never appeared in the gestures of the Span-ish speakers, and they represent a temporal hier-archy not found in motion events themselves.
Such hierarchical combinations are centralto the language engine, enabling the production
of an infinite set of utterances with a finite set ofelements. Thus, the emergence of this construc-tion in NSL represents a shift from gesture-liketo language-like expression.
It is informative that the first-cohort signers,who originated the language when they werechildren in the late 1970s, continue to produce ittoday in a form closer to its gestural model. Wetake this as an indication of the extent of theirimpact on NSL before the mid-1980s, when theyreached adolescence. The children who werearriving in the mid-1980s then became NSL’ssecond wave of creative learners, picking upwhere the first cohort left off and making chang-es that were never fully acquired by now-ado-lescent first-cohort signers (15, 16). The differ-ence today between first- and second-cohortsigners therefore indicates what children coulddo that adolescents and adults could not. It ap-pears that the processes of dissection, reanalysis,and recombination are among those that becomeless available beyond adolescence. Such an ageeffect is consistent with, and would partiallyexplain, the preadolescent sensitive period forlanguage acquisition discussed in other work(21, 22). Using their early learning skills, thosewho were still children in the mid-1980s devel-oped NSL into the more discrete and combina-torial system that they, and the children whofollowed in the 1990s, still exhibit today.
Because NSL is such a young language, re-cently created by children, its changes reveallearning mechanisms available during child-hood. Our observations highlight two of thesemechanisms. The first is a dissecting, segmentalapproach to bundles of information; this analyt-ical approach appears to override other patternsof organization in the input, to the point ofbreaking apart previously unanalyzed wholes.
The second is a predisposition for linear se-quencing; sequential combinations appear evenwhen it is physically possible to combine ele-ments simultaneously, and despite the availabil-ity of a simultaneous model. We propose thatsuch learning processes leave an imprint on lan-guages—observable in mature languages in theircore, universal properties—including discrete el-ements (such as words and morphemes) com-bined into hierarchically organized constructions(such as phrases and sentences).
Accordingly, these learning mechanismsshould influence language emergence andchange as long as there are children availableto take up a language. Consistent with thisaccount, linear sequencing of elements (evenwhen representing simultaneous aspects of anevent) appears to be an initially favored de-vice in language emergence (23). For exam-ple, strong word order regularities are welldocumented in creoles, young languages thatarise out of particular social situations oflanguage contact (24–26). Some theories ofcreolization hold that child learners drive thisprocess (27, 28). Our findings, in line withthese approaches, favor a degree of childinfluence in identifying and sequencing ele-ments (29).
However, these learning predispositionswill not fully determine a language’s eventualstructure. For example, many sign languagesuse simultaneous combinations in addition tosequential ones. Nonetheless, even in caseswhere adults use simultaneous constructions,the pattern of children’s acquisition points toa preference for linear sequencing (23). Forexample, research on the acquisition ofAmerican Sign Language (ASL) (23, 30) hasshown that children initially break complex
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
Cohort 3 Cohort 2Cohort 1 Gesturers Cohort 3 Cohort 2Cohort 1 Gesturers
Pro
po
rtio
n o
f ex
pre
ssio
ns
A BFig. 2. (A) The proportion of ex-pressions that include mannerand path that articulate themsimultaneously within a singlegesture or sign. Proportions werecomputed for each participant.Bars indicate mean proportionsfor each of the four groups; errorbars indicate SE. All of the co-speech gestures and most of thefirst-cohort signers’ expressionsarticulated manner and path si-multaneously. Second- andthird-cohort signers produce rel-atively fewer expressions of thistype. Proportions differ signifi-cantly across the four groups (Kruskal-Wallis, P � 0.02, df � 3, �2 � 10.8). Post hoc analyses withBonferroni adjustment indicate that the Spanish speakers differ significantly from second-cohortsigners (Mann-Whitney, P � 0.04) and marginally from third-cohort signers (Mann-Whitney, P �0.06). (B) The proportion of expressions that include manner and path that articulate themsequentially in a string of manner-only and path-only elements. Proportions were computed foreach participant. Bars indicate mean proportions for each of the four groups; error bars indicate SE.These sequential expressions are never observed in the co-speech gestures. First-cohort signerssometimes produce such sequences; second- and third-cohort signers include them in most of theirexpressions. Proportions differ significantly across the four groups (Kruskal-Wallis, P � 0.01, df �3, �2 � 14.7). Post hoc analyses with Bonferroni adjustment indicate that the Spanish speakersdiffer significantly from both second-cohort signers (Mann-Whitney, P � 0.02) and third-cohortsigners (Mann-Whitney, P � 0.03).
R E P O R T S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1781
verb expressions down into sequential mor-phemes, rather than produce multiple verbelements together in the single, simultaneousmovement found in adult models. In ASL,oversegmentation during acquisition was ob-served across a number of element types,including the agent and patient of a transitiveevent, and, as in NSL, the manner and path ofa motion event. These elements correspond tosemantic units that are relevant to lexicaliza-tion patterns in many (possibly all) languages(20). Thus, the elements chosen for segmen-tation may reveal the very primitives thatchildren are predisposed to seek out as basic,grammatical units.
Such primitives, and the processes thatisolate and recombine them, are central tochildren’s language-learning machinery to-day. Whether these drove the formation of thevery first human languages depends onwhether languages shaped learning abilities,or vice versa. We speculate that a combina-tion of the two was the case. Once languagedeveloped a discrete and hierarchical nature,children who tended toward analytical andcombinatorial learning would have an advan-tage acquiring it (3). In this way, evolutionarypressures would shape children’s language-learning (and now, language-building) mech-anisms to be analytical and combinatorial. Onthe other hand, once humans were equippedwith analytical, combinatorial learning mech-anisms, any subsequently learned languageswould be shaped into discrete and hierarchi-cally organized systems (4, 5).
Although our findings are consistent withboth directions of effect in the evolution oflearners and languages, they are at odds withaccounts in which such attributes evolvedexternally, were passed from generation togeneration solely through cultural transmis-sion, and were never reflected in the nature ofthe learning mechanism (7). In studies ofmature languages, the potential imprint of thelearning mechanism is redundant with, andhence experimentally obscured by, preexist-ing language structure. But the rapid restruc-turing of Nicaraguan Sign Language as it ispassed down through successive cohorts oflearners shows that even where discretenessand hierarchical combination are absent fromthe language environment, human learningabilities are capable of creating them anew.
References and Notes1. C. F. Hockett, Refurbishing Our Foundations: Elemen-
tary Linguistics from an Advanced Point of View (Ben-jamins, Philadelphia, 1987).
2. M. H. Christiansen, S. Kirby, Trends Cognit. Sci. 7, 300(2003).
3. R. Jackendoff, Foundations of Language: Brain, Mean-ing, Grammar, Evolution (Oxford Univ. Press, NewYork, 2002).
4. M. D. Hauser, N. Chomsky, W. T. Fitch, Science 298,1569 (2002).
5. S. Pinker, P. Bloom, Behav. Brain Sci. 13, 707 (1990).6. S. Kirby, Function, Selection, and Innateness: The
Emergence of Language Universals (Oxford Univ.Press, New York, 1999).
7. M. Tomasello, in Language Evolution, M. H. Chris-tiansen, S. Kirby, Eds. (Oxford Univ. Press, New York,2003), pp. 94–110.
8. L. Polich, But with Sign Language You Can Do So Much(Gallaudet Univ. Press, in press).
9. R. J. Senghas, thesis, University of Rochester (1997).10. S. Goldin-Meadow, in Language Acquisition: The State
of the Art, E.Wanner, L. R. Gleitman, Eds. (CambridgeUniv. Press, New York, 1982), pp. 51–77.
11. J. P. Morford, Lang. Commun. 16, 165 (1996).12. M. Coppola, thesis, University of Rochester (2002).13. J. Kegl, A. Senghas, M. Coppola, in Language Creationand Language Change: Creolization, Diachrony, andDevelopment, M. DeGraff, Ed. (MIT Press, Cambridge,MA, 1999), pp. 179–237.
14. A. Senghas, thesis, Massachusetts Institute of Tech-nology (1995).
15. A. Senghas, M. Coppola, Psychol. Sci. 12, 323 (2001).16. A. Senghas, Cogn. Dev. 18, 511 (2003).17. See supporting data on Science Online.18. S. Kita, A. Ozyurek, J. Mem. Lang. 48, 16 (2003).19. D. McNeill, Hand and Mind: What Gestures RevealAbout Thought (Univ. of Chicago Press, Chicago,1992).
20. L. Talmy, in Grammatical Categories and the Lexicon,Vol. III, T. Shopen, Ed. (Cambridge Univ. Press, Cam-bridge, 1985), pp. 57–149.
21. E. Lenneberg, Biological Foundations of Language(Wiley, New York, 1967).
22. E. L. Newport, Cogn. Sci. 14, 11 (1990).23. E. Newport, in Aspects of the Development of Com-
petence, W. A. Collins, Ed., vol. 14 of MinnesotaSymposia on Child Psychology (Erlbaum, Hillsdale, NJ,1981), pp. 93–124.
24. J. Holm, Pidgins and Creoles, Vol. 1: Theory andStructure (Cambridge Univ. Press, Cambridge, 1988).
25. M. DeGraff, Ed., Language Creation and LanguageChange: Creolization, Diachrony, and Development(MIT Press, Cambridge, MA, 1999).
26. R. W. Anderson, in Pidginization and Creolization asLanguage Acquisition, R. Anderson, Ed. (Newbury,Rowley, MA, 1983), pp. 1–56.
27. D. Bickerton, Behav. Brain Sci. 7, 173 (1984).28. G. Sankoff, S. Laberge, Kivung 6, 32 (1973).29. Unlike NSL, creoles draw much of their vocabulary
and possibly some grammatical structure from thelanguages in contact where they arise; much debatesurrounds the question of the nature and degree ofthis influence (25).
30. R. P. Meier, J. Mem. Lang. 26, 362 (1987).31. We thank the Nicaraguan participants for their en-
thusiastic participation; the Melania Morales Schoolfor Special Education, the National Nicaraguan Asso-ciation of the Deaf (ANSNIC), and the NicaraguanMinistry of Education, Culture, and Sports (MECD) fortheir assistance and cooperation; Quaker House,Managua, for providing testing facilities; A. Engelman,M. Flaherty, E. Housman, S. Katseff, S. Littman, J.Pyers, M. Santos, and P. Shima for assistance withdata collection and analysis; and S. Bogoch, P. Ha-goort, S. Pinker, and R. Short for comments on earlierversions of the manuscript. Supported by the Lan-guage and Cognition Group at the Max Planck Insti-tute for Psycholinguistics, the Netherlands Organiza-tion for Scientific Research (NWO) project051.02.040 (A.O.), National Institute on Deafnessand Other Communication Disorders (NIDCD) grantR01 DC00491 (Susan Goldin-Meadow and A.O.),Turkish Academy of Sciences grant HAO/TUBA-GEBIP/2001-2-16 (A.O.), a visiting faculty position inpsychology at Harvard University (A.S.), and NIDCDgrant R01 DC05407 (A.S.).
Supporting Online Materialwww.sciencemag.org/cgi/content/full/305/5691/1779/DC1Materials and MethodsMovies S1 and S2
11 May 2004; accepted 15 July 2004
Two Distinct Actin NetworksDrive the Protrusion ofMigrating Cells
A. Ponti, M. Machacek, S. L. Gupton, C. M. Waterman-Storer,*†G. Danuser*†
Cell migration initiates by extension of the actin cytoskeleton at the leadingedge. Computational analysis of fluorescent speckle microscopy movies ofmigrating epithelial cells revealed this process is mediated by two spatiallycolocalized but kinematically, kinetically, molecularly, and functionally distinctactin networks. A lamellipodium network assembled at the leading edge butcompletely disassembled within 1 to 3 micrometers. It was weakly coupled tothe rest of the cytoskeleton and promoted the random protrusion and retrac-tion of the leading edge. Productive cell advance was a function of the secondcolocalized network, the lamella, where actomyosin contraction was integratedwith substrate adhesion.
Cell migration involves a coordinated cycleof plasma membrane protrusion at the lead-ing edge, adhesion site formation under theprotrusion, disruption of older adhesionsites at the cell rear, and cytoskeleton con-traction against adhesions to yield cell bodymovement (1). Protrusion is thought to re-sult from actin filament (F-actin) polymer-ization against the plasma membrane (2),with the polymerization rate regulated bythe rate of monomer addition to the fast-
growing (“barbed”) ends of filaments. Thismay depend on actin-related protein 2/3(Arp2/3) complex activation, which createsfree barbed ends by branching and de novonucleation of filaments (dendritic nucle-ation) (3), and on actin depolymerizing fac-tor (ADF) cofilin, which creates freebarbed ends by severing preexisting fila-ments and promoting depolymerization offree filament “pointed” ends (4). Filamentgrowth is limited by barbed end–capping
R E P O R T S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1782
proteins and depletion of the polymeriza-tion-competent pool of actin monomers (5).
We exploited quantitative fluorescentspeckle microscopy (qFSM) (6) to studythe dynamic organization of F-actin in mi-grating cells and define its relationship tocell protrusive behavior. In FSM, a nonuni-form pattern of fluorophores forms by co-polymerization of F-actin from a pool ofactin monomers with a very low ratio be-tween fluorescently labeled and unlabeledmonomers. In high-resolution images, flu-orophore clusters are detected as local in-tensity maxima called speckles (fig. S1).We imaged speckles containing 2 to 8 flu-orescent monomers. Computational track-ing of �105 speckles per FSM movie (7)and statistical processing of their intensityfluctuations (8) allowed us to map F-actinflow (kinematics) and turnover (kinetics)with submicrometer resolution (9).
We quantified F-actin dynamics in newt lungepithelial cells (Fig. 1, A and B, and movie S1)and potoroo kidney (PtK1) epithelial cells (Fig.1, C and D, and movie S2). In kinematic maps,both cell types exhibited a thin (1 to 3 m) bandalong the leading edge where speckles under-went fast flow (300 to 500 nm/min) toward thecell center (Fig. 1, A and C, and movies S3 andS4). The band abutted a much larger area ofslower retrograde flow (100 to 250 nm/min).Steady-state maps of F-actin kinetics showed a�1-m-wide band of strong polymerizationalong the leading edge that transitions into anequally narrow band of depolymerization (Fig.1, B and D), which corresponded in kinematicmaps to the region of negative speed gradients.Animated kinetic maps (movies S5 and S6) re-vealed that bursts of depolymerization also oc-curred at the leading edge. Beyond these bands,kinetic maps displayed a random pattern of foci1 to 2 m in diameter, where F-actin assembledand disassembled in cycles of �40 to 50 s. Werefer to the zone with fast retrograde flow andjuxtaposed narrow bands of polymerization anddepolymerization as the lamellipodium and thezone characterized by slower flow and a punc-tate pattern of filament turnover as the lamella.The lamellipodium and lamella had distinct mo-lecular signatures, with high concentrations ofArp2/3 and ADF/cofilin in the lamellipodiumand myosin II and tropomyosin present exclu-sively in the lamella (fig. S2).
Given the kinematic, kinetic, and moleculardifferences, we sought mathematical criteria thatwould allow us to determine the relationshipbetween the lamellipodium and lamella overtime. We tracked the cell border and calculated
the rates of network assembly, disassembly, andretrograde flow along regularly spaced profilesperpendicular to the edge (Fig. 1E). In 80 pro-files analyzed, the assembly rate peaked at �1m from the leading edge, followed closely by apeak in depolymerization (Fig. 1F). Before thevariation in both rates diminished, a second peakof net assembly (Fig. 1F, arrowhead) indicatedthe location where lamellipodium kinetic behav-ior turned into lamella kinetic behavior. Thiskinetic boundary colocalized with the first localminimum of the retrograde flow speed (Fig. 1G).Together, these criteria permitted robust auto-matic extraction of the lamellipodium-to-lamellatransition (Fig. 1E, white line).
Integration of the net assembly rate (thedifference between areas A and D in Fig. 1F)revealed the amount of polymer generated anddisassembled within the boundary of the lamel-lipodium. Most (85 to 90%) of the actin net-work underwent a complete cycle of assemblyand disassembly within the first 1 to 3 m fromthe cell edge. Thus, lamellipodium and lamellaare composed of materially nearly decouplednetworks, suggesting that the lamellipodiumdoes not supply substantial filaments to otheractin assemblies in the cell (10). The tightspatial juxtaposition of assembly and dis-assembly likely generates monomer gradientshigh enough to maintain an efficient treadmill
Department of Cell Biology, The Scripps ResearchInstitute (TSRI), La Jolla, CA 92037, USA.
*These authors contributed equally to this work.†To whom correspondence should be addressed.E-mail: [email protected] (C.M.W.-S.) [email protected] (G.D.)
B F-actin turnover
210 3 4 5 6
210 3 4 5 6210 3 4 5 6
2100
1
-101
3 4 5 6
A F-actin flow
C D
E Net assembly of F-actin F
G
(s)
-1
Depolymerization Polymerization Profile (1) Profile (2)
(µm/m
in)(s
-1 )
5 µm
5 µm
5 µm
Polymerization
Depolymerization
Lamella
Lamellipodium
500 nm
350
300
250
200
150
100
50
nm/min
0
300200100
0
400500
(µm)(µm)
(µm)
Retrograde flow rateRetrograde flow rate
Net assembly
Net assembly rate
Net assembly
Depolymerization rate
Polymerization rate
A
D
Fig. 1. F-actin dynamics characterized by qFSM in (A and B) a newt lung cell (movies S1, S3, andS5) and (C and D) a PtK1 cell (movies S2, S4, and S6). [(A) and (C)] Time-averaged F-actin flow (60frames); colors encode flow speed, and vectors, flow direction. Inset: Individual speckle trajectoriesover 200 s; time evolution, dark blue to light green. [(B) and (D)] Time-averaged F-actin turnover(60 frames). Red channel, assembly rate; green, disassembly rate. (E) Net F-actin assembly. Black,negative assembly rates; white, positive assembly rates. The lamellipodium-to-lamella transition(white line) (movie S8) was computed from rate profiles (along the red lines) of net assembly andflow. (F) Rate profiles indicate that the lamellipodium-to-lamella transition coincides with the firstlocal maximum of net assembly (arrowhead) after the first maximum in depolymerization (dashedgreen line). A, integrated assembly; D, integrated disassembly. (G) The kinetically defined transition(black asterisks) colocalizes with the first local minimum in flow rate (blue asterisks). Examples arecalculated from the yellow profiles (1) and (2) in (E).
R E P O R T S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1783
of actin turnover based on diffusive transport(11–13).
Next, we partitioned speckles into two class-es (Fig. 2A): fast-moving and short-living (class1) and slow-moving and long-living (class 2).Class 1 speckles clustered in the lamellipodium,whereas 90% of the speckles in the lamellabelonged to class 2 (Fig. 2B). However, 33% ofthe speckles falling into the area between theleading edge and the lamellipodium-lamellatransition had the characteristics of lamellaspeckles (Fig. 2B, inset). We examined the en-semble behavior of these speckle classes andfound that class 1 speckles displayed the kineticsignature of the lamellipodium (Fig. 2C), where-as class 2 speckles displayed the signature of alamella network (Fig. 2D) that extended all theway to the leading edge. This coexistence of twospatially overlapping yet kinetically and kine-matically distinct networks was masked in jointevaluation of all speckles (Fig. 1, B and D),because class 1 speckles outnumbered class 2speckles near the cell boundary.
We probed the molecular characteristicsof the two networks in a series of pharmaco-logical perturbation experiments. First, weapplied blebbistatin to inhibit nonmuscle my-
osin II adenosine triphosphatase activity (14).In agreement with myosin II localization data(fig. S2), blebbistatin reduced lamella retro-grade flow but not lamellipodium flow (Fig.3A), with little effect on the rates of filamentturnover in either network.
We next treated cells with 0.5 M cy-tochalasin D (cytD) (Fig. 3B) to inhibit po-lymerization of free barbed ends (15). Space-time diagrams of F-actin turnover, edge dis-placement, and network flow computed alongthe leading edge (Fig. 3C) (9) revealed that,before cytD perfusion, periodic bursts of po-lymerization at the leading edge transformedin equal parts into protrusion and F-actinretrograde flow (Fig. 3C, dashed white lines).Cross-correlation analysis of the three param-eters (Fig. 3D) confirmed a positive correla-tion between edge displacement and networkturnover and negative correlations for the twoother parameter combinations. This behaviorchanged after cytD perfusion. The correlationbetween turnover and both edge displacementand network flow broke down, and the cor-relation between edge displacement and net-work flow switched from negative to positivevalues (Fig. 3D). Thus, cytD selectively re-
moved the lamellipodium network by cap-ping the free barbed ends, and the synchro-nous retraction of the leading edge and net-work (movie S7) is associated with lamellacontraction (16). Despite cytD treatment, thelamella was in a state of predominant disas-sembly for only �6 min (disassembly:assem-bly ratio of 1.8 � 0.2). Subsequently, peri-odic patterns of assembly and disassemblywere re-established (disassembly:assem-bly ratio of 1.2 � 0.1 in cytD versus 1.4 �0.1 before perfusion), indicating that much ofthe kinetic activity in the lamella network isinsensitive to cytD. However, the mainte-nance of the lamella position and its advance-ment required barbed end assembly. Washoutof cytD immediately re-established the lead-ing edge position and lamellipodial kineticand kinematic signatures.
Similarly, inhibiting depolymerization bystabilizing filaments with 1 M jasplakinolide(11) also affected the lamellipodium selectively.Within minutes of jasplakinolide application,both filament turnover and retrograde flow werestopped in the lamellipodium, whereas the la-mella appeared unaffected (Fig. 3E). The loss ofthe lamellipodium did not alter edge position,and the same region now showed the signaturesof the lamella, providing additional evidence fortwo distinct yet spatially overlapping networks.
Which of the two networks drives cell pro-trusion? We compared leading edge displace-ment, network turnover, and retrograde flow inmovies of cells that displayed very slow netadvancement to those with persistent rapid pro-trusion. For cells with slow edge advancement,without exception, we found periodic cycles ofedge protrusion and retraction (17). They corre-lated with cycles of polymerization and depoly-merization and of faster and slower retrogradeflow. F-actin flow in the lamella (measuredproximal to the lamellipodium-lamella transi-tion) exhibited a periodicity highly correlatedwith the lamellipodium flow (Fig. 4A), but theamplitude modulation was damped by 69% (fig.S4), confirming the rather weak material cou-pling between the two networks.
Next, we examined cells with rapid, persis-tent edge protrusion (Fig. 4B and movie S2).One possibility was that the balance betweenforward edge movement and lamellipodium ret-rograde flow could be tipped toward edge move-ment. However, when polymerization increased(movie S6), it was still accompanied by acceler-ation of retrograde flow (movie S4). Alternative-ly, propulsion of the leading edge by increasedpolymerization could be accompanied by a wid-ening of the lamellipodium. Instead, we foundthat the cell boundary and lamellipodium-to-lamella transition advanced in concert (Fig. 4C),creating the impression of a lamellipodium surf-ing on a forward-growing lamella (movies S8and S9). Thus, persistent protrusion depends onthe local expansion of the lamella network. La-mellipodium polymerization is not sufficient.
Fig. 2. Distinction of spatially overlapping lamellipodium and lamella by classification of specklevelocity and lifetime. (A) Separation of fast-moving and short-living speckles (class 1, red) andslow-moving and long-living speckles (class 2, black). LTth, lifetime threshold; Vth, velocity thresh-old. (B) Thresholds are set to minimize the number of class 1 speckles in the lamella whilemaximizing the number in the lamellipodium. This multi-objective optimization has a uniquesolution, because class 1 speckles cluster in the lamellipodium with a residual occurrence of �10%in the lamella. Class 2 speckles dominate the lamella but expand all the way to the leading edge,contributing 33% to the lamellipodium region. (C) Turnover calculated from class 1 speckles showsthe spatial kinetic signature of the lamellipodium. (D) Turnover calculated from class 2 specklesshows the spatial kinetic signature of the lamella.
R E P O R T S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1784
To determine if the expansion of the lamellaspatially correlated with the establishment oflinkages between the cytoskeleton and the extra-cellular matrix, we filmed actin dynamics byFSM and localized focal adhesions using greenfluorescent protein (GFP)-tagged vinculin.Protrusive edge sections (Fig. 4D, arrow-heads) were consistently positioned just be-yond the distalmost portion of focal adhesionswhere the adhesions initiated at the lamellipo-dium-to-lamella transition.
Thus, qFSM of F-actin dynamics in migrat-ing cells reveals two kinetically, kinematically,and molecularly distinct F-actin networks at theleading edge of epithelial cells, which spatiallyoverlap and yet are only weakly coupled, andwhose transition may be defined by the initiationof substrate-cytoskeleton linkages (fig. S5). Pro-ductive advancement of the leading edge re-quires expansion of the lamella, where actomy-osin contractile forces are coupled to substrateadhesion and which depends on cytD-insensi-tive filament assembly, possibly mediated byformins (18, 19). In contrast, lamellipodiumprotrusion and retraction probably serve anexploratory function or could provide rapidresponses to extracellular cues. However, per-sistent advancement of the cell relies on theunderlying lamella.
References and Notes1. D. A. Lauffenburger, A. F. Horwitz, Cell 84, 359 (1996).2. J. A. Theriot, T. J. Mitchison, Nature 352, 126 (1991).3. R. D. Mullins, J. A. Heuser, T. D. Pollard, Proc. Natl.Acad. Sci. U.S.A. 95, 6181 (1998).
4. M. Ghosh et al., Science 304, 743 (2004).5. T. D. Pollard, G. B. Borisy, Cell 112, 453 (2003).6. G. Danuser, C. M. Waterman-Storer, J. Microsc. 211,
191 (2003).7. P. Vallotton, A. Ponti, C. M. Waterman-Storer, E. D.
Salmon, G. Danuser, Biophys. J. 85, 1289 (2003).8. A. Ponti, P. Vallotton,W. C. Salmon, C.M.Waterman-
Storer, G. Danuser, Biophys. J. 84, 3336 (2003).9. Materials and methods are available as supporting
material on Science Online.10. J. V. Small, K. Rottner, I. Kaverina, Curr. Opin. Cell
Biol. 11, 54 (1999).11. L. P. Cramer, Curr. Biol. 9, 1095 (1999).12. R. S. Fischer, K. L. Fritz-Six, V. M. Fowler, J. Cell Biol.
161, 371 (2003).13. V. C. Abraham, V. Krishnamurthi, D. L. Taylor, F. Lanni,
Biophys. J. 77, 1721 (1999).14. A. F. Straight et al., Science 299, 1743 (2003).15. P. Sampath, T. D. Pollard, Biochemistry 30, 1973
(1991).16. P. Forscher, S. J. Smith, J. Cell Biol. 107, 1505 (1988).17. G. Giannone et al., Cell 116, 431 (2004).18. S. H. Zigmond et al., Curr. Biol. 13, 1820 (2003).19. C. Higashida et al., Science 303, 2007 (2004).20. Supported by research grant no. RGY5-2002 from the
Human Frontiers Science Programme and no.GM67230 from the National Institutes of Health.This is TSRI manuscript no. 16575-CB.
Supporting Online Materialwww.sciencemag.org/cgi/content/full/305/5691/1782/DC1Materials and MethodsFigs. S1 to S5Movies S1 to S9
20 May 2004; accepted 6 August 2004
Fig. 3. Probing molecular characteristics of the two networks by small molecule inhibitors. (A)Perfusion with 100 M blebbistatin slows lamella F-actin flow exclusively (left two panels),with little effect on F-actin turnover (right two panels). P, polymerization; D, depolymerization.(B) Perfusion with 0.5 M cytD decreases F-actin flow in the lamellipodium and inducesretraction of the leading edge (white lines) (fig. S3). Washout rescues cell edge position andlamellipodium flow rate. (C) Space-time diagrams of F-actin network turnover, edge displace-ment, and F-actin flow along the leading edge (fig. S3) (9) during perfusion and washout ofcytD.White dashed lines highlight periodicities. (D) Correlation between edge displacement (E)and F-actin flow (F); between edge displacement and F-actin turnover (T); and between flowand turnover. (E) Perfusion with 1 M jasplakinolide selectively removes the kinetic andkinematic signature of the lamellipodium. The white line indicates the lamellipodium-to-lamella transition before drug application.
R E P O R T S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1785
Zooming In on a QuantitativeTrait for Tomato Yield UsingInterspecific Introgressions
Eyal Fridman,1*† Fernando Carrari,2† Yong-Sheng Liu,1‡Alisdair R. Fernie,2 Dani Zamir1§
To explore natural biodiversitywe developed and examined introgression lines (ILs)containing chromosome segments of wild species (Solanum pennellii) in the back-ground of the cultivated tomato (S. lycopersicum). We identified Brix9-2-5, whichis a S. pennellii quantitative trait locus (QTL) that increases sugar yield of tomatoesand was mapped within a flower- and fruit-specific invertase (LIN5). QTL analysisrepresenting five different tomato species delimited the functional polymorphismof Brix9-2-5 to an amino acid near the catalytic site of the invertase crystal,affecting enzyme kinetics and fruit sink strength. These results underline the powerof diverse ILs for high-resolution perspectives on complex phenotypes.
The genetic basis of many natural phenotypestakes the form of a continuous range rather thandiscrete classes. The complexity of traits show-ing continuous distribution often results fromthe segregation of numerous QTL, whose ex-pression is modified both by the environment
and by genetic background (1). Genetic resolu-tion of quantitative traits in populations thatsegregate simultaneously for different QTLscattered throughout the genome [e.g., secondfilial generation (F2), backcross, and recombi-nant inbreds] is low compared with QTL anal-
ysis in lines that segregate for a single region(i.e., ILs in plants and congenic strains in ani-mals) (2). Multiple segregating QTL at thewhole-genome level tend to mask the effects ofone another by introducing high variances instatistical analyses. In sharp contrast, ILs areidentical for the entire genome except for asingle introgressed region, and therefore allthe phenotypic variation in these lines isassociated with the introduced segment.The use of such targeted population struc-tures increased the identification power for
1The Robert H. Smith Institute of Plant Sciences andGenetics in Agriculture, Faculty of Agriculture, TheHebrew University of Jerusalem, Post Office Box 12,Rehovot 76100, Israel. 2Department Willmitzer, Max-Planck-Institut fur Molekulare Pflanzenphysiologie,Am Muhlenberg 1, 14476 Golm, Germany.
*Present address: Department of Molecular, Cellularand Developmental Biology, University of Michigan,Ann Arbor, MI 48109–1048, USA.†These authors contributed equally to this work.‡Present address: Laboratory of Plant Molecular Biol-ogy, The Rockefeller University, 1230 York Avenue,New York, NY 10021, USA.§To whom correspondence should be addressed.E-mail: [email protected]
Fig. 4. The contribution of lamellipodium and lamella to edge protrusion. (A)Space-time diagrams of F-actin turnover, edge displacement (displ.), andF-actin flow along the leading edge and lamella F-actin flow adjoining thelamellipodium-to-lamella transition (fig. S4). Cycles of assembly and disas-sembly at the leading edge (period, 0.01 Hz) are transformed in equal partsinto oscillatory edge movement and retrograde flow (white dashed lines).The same period is found in lamella flow (there is a high correlation
between flow at the leading edge and lamella flow, F versus LF), but theamplitudes are markedly decreased (cf. fig. S4). (B and C) Co-movement ofthe leading edge and the lamellipodium-to-lamella transition during persis-tent cell protrusion [the red arrow in (B) and arrows in (C)] (movie S9). (D)Overlay of GFP-vinculin (white), marking focal adhesions on the actinturnover map and showing protrusions of the leading edge (arrowheads) andthe position of the lamellipodium-lamella transition (white line).
R E P O R T S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1786
QTL by several times in both plants andanimals (3, 4).
QTL cloning projects in plants have fo-cused primarily on variation derived fromnaturally divergent genetic resources andhave generated new biological insights aboutplant development, whereby some of the ef-fects could be delimited to single-nucleotidealterations (5–8). Biodiversity research incrop plants has shown that when chromo-some segments of wild species are intro-gressed into cultivated varieties, it is possibleto identify genomic regions that substantiallyimprove yield (9). To enhance the progress oftomato breeding, we developed a populationof 76 segmental ILs that are composed ofmarker-defined genomic regions of the wildspecies S. pennellii (accession code LA716),substituting for the homologous intervals ofthe cultivated variety M82 [S. lycopersicum;the taxonomic classification of tomato in thegenus Solanum is available in (10)]. The ILsthat represent the entire genome partition thegenetic map into 107 bins, which are definedby singular or overlapping segments (11).Over the past 10 years, the tomato ILs havebeen assayed for yield-associated traits andthe data are presented, in silico, in a searchengine that displays the components of thegenetic variation (12).
The QTL database creates a firm basis toinvestigate the genetic control of yield-asso-ciated traits. An important yield componentin “ketchup tomatoes” is the total solublecontent of the fruit measured in refractometerbrix units (consisting mainly of the sugarsglucose and fructose). The S. pennellii ILdata for brix (B) show 25 different genomicregions with significant effects on the traitrelative to M82; in the majority of thesecases, the S. pennellii alleles increased B (fig.S1). To uncover the molecular control of B,we characterized the QTL Brix9-2-5, the ef-fects of which ranged from an increase of 11
to 25%, depending on genetic backgroundand environmental factors (13, 14). Thismoderate QTL improves B without reducingtotal yield, thus increasing the sugar outputper unit area, which is a key yield parameterin industrial tomatoes (9). High-resolutiongenetic mapping delimited Brix9-2-5 to a sin-gle-nucleotide polymorphism (SNP)–definedregion of 484 base pairs spanning part of thethird exon and the third intron of the cell-wall(CW) invertase (LIN5) (14). Another compo-nent of the complexity in the molecular anal-ysis of this gene is that LIN5 is a member ofa larger gene family including three addition-al CW invertases (LIN6, LIN7, and LIN8).After investigating the RNA profile of theLIN family, we concluded that the windowof exclusivity of LIN5 expression is in theconductive tissue of the flower’s ovary,fruit placenta, and pericarp during the earlystage of cell division (15) (Fig. 1). Theexpression of LIN5 in the conducting tissuenext to a potential “sugar-unloading site”near the ovaries is consistent with the roleof LIN5 as a “sink gene” that regulates theability of the fruit to import photosyntheticsugars (16). Because of the partially dom-inant nature of the S. pennellii allele inelevating fruit B (14), we compared tran-scription rates of the wild and cultivatedspecies alleles in young ovaries of het-erozygous plants. Steady-state mRNA lev-els of the S. pennellii allele relative to the S.lycopersicum allele were statistically simi-lar (fig. S2), indicating that the QTL effectwas not due to differential transcriptionmodulation by the third intron (14). Tocompare the quantities of the LIN5 protein,we extracted the CW-bound enzymes fromthe ovules of the Brix9-2-5 nearly isogenic
lines and analyzed them on protein gelblots with antibodies raised against CWinvertase (17). The lines did not differ sta-tistically in the mean quantity of LIN5 pep-tide (fig. S3). However, CW invertase ac-tivity was statistically different (P � 0.01)between the genotypes, with values three tofive times as high in lines homozygous forthe S. pennellii allele compared with thoseof the S. lycopersicum lines (Table 1).
The fact that the IL9-2-5 differed from thecontrol for enzyme activity in flowers did notmean that these differences map to the sameLIN5 interval as the fruit sugar QTL, which ismanifested 50 days after flowering. An ex-ample for the complexity of the genetic fac-tors that regulate quantitative traits was re-vealed for Drosophila alleles of alcohol de-hydrogenase of differing activity, which iscontrolled by at least three different zones ofthe gene (18). To evaluate whether the dif-ferences in CW invertase activity were asso-ciated with the 484–base pair B QTL inter-val, we assayed the high-resolution recombi-nant families that span the gene (Fig. 2). Themapping analysis demonstrates that maturefruit B and CW invertase activity in flowerovaries are associated with the same LIN5interval. The data presented so far imply thatthe three amino acid differences in the thirdexon are responsible for the QTL effects(Fig. 3A).
Interspecific advanced backcross breedingpopulations in tomato involving S. pimpineli-follium, S. habrochaites, S. neorickii, and adifferent accession of S. pennellii (LA1657)from that used for the IL construction werenext assayed for yield-associated traits (in-cluding B) in three to seven locations. Brix9-2-5 maps to the middle of the short arm of
Fig. 1. LIN5 expression in the conductive tissuesof the developing tomato fruit. In situ localiza-tion of LIN5 transcripts in a longitudinal sectionof an ovary at anthesis showing expressionmainly in the conductive tissues within theplacenta that lead to the developing seeds aswell as the surrounding pericarp.
Fig. 2.Map of the effect of Brix9-2-5 on B and on CW invertase activity. Each recombinant is shownby a combination of empty and hatched bars, representing the S. lycopersicum and S. pennelliisequence, respectively. Each SNP is represented by its position in the S. pennellii (top) and S.lycopersicum nucleotides. The SNP2878, which underlines the QTN effects, is boxed. Phenotypiceffects of each recombinant family’s alleles on the B and the CW invertase activity is shown as thepercentage difference from the S. lycopersicum line. Full bars and asterisks denote a significantdifference from the control (P � 0.001).
R E P O R T S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1787
chromosome 9; none of these populationsrevealed a B QTL on the short arm of chro-mosome 9, in any of the sites tested (19–22)(Fig. 3A). Sequencing of the QTL region ofLIN5 from the above accessions showed thatthey all share the Asp366 and Val373 residueswith S. pennellii (LA716). However, Asp348
was uniquely associated with LA716 (Fig.3A). Interestingly, multiple alignment ofLIN5 with its duplicated family members(LIN6, LIN7, and LIN8) and other plant in-vertases exposed aspartate as a conservedresidue at this position (Fig. 3B), suggesting anonneutral role for this amino acid.
The candidate quantitative trait nucleotide(QTN) (SNP2878; Fig. 2) responsible for theAsp348 substitution was evaluated in comple-mentation tests in an attempt to study itseffects on enzyme activity. We used a yeastinvertase–deficient strain that completelylacks the ability to degrade sucrose (23) as ahost for plasmids harboring the tomato LIN5cDNA from S. lycopersicum (LIN5lyc-E,where the letter in the superscript depicts theidentity of the amino acids at positions 348),IL9-2-5 (LIN5pen-D), and the mutated S. lyco-persicum allele engineered to code for aninvertase with the Asp348 residue (LIN5lyc-D).Unlike the empty-vector control transfor-mants, the three invertase-transformed yeaststrains exhibited substantial growth on su-crose, with LIN5pen-D and LINlyc-D allelesseemingly complementing the invertase defi-ciency of the yeast strain more faithfully thandid the LIN5lyc-E allele (fig. S4). These dif-ferences could not be attributed to changes inthe quantity of the enzyme because immuno-blot quantification did not reveal significantdifferences in the total amount between thethree different yeast genotypes (fig. S5).
When sucrose hydrolysis activities of the ex-pressed invertases from the three strains wereplotted as a function of substrate concentra-tion, the double reciprocal plots were linear(Fig. 4) and the Michaelis constant for su-crose (Km[sucrose]) values calculated fromthese plots are 31.0, 11.6, and 5.1 mM forLIN5lyc-E, LIN5pen-D, and LIN5lyc-D alleles,respectively. The values for the S. pennelliiand the mutated S. lycopersicum enzymeswere similar to those previously reported forplant invertases, but the nonmutated S. lyco-persicum was considerably less efficient thanthe values documented in the BRENDA da-tabase (www.brenda.uni-koeln.de). Thecomplementation data indicate that Asp348
plays a role in enhancing the activity of LIN5and establish that SNP2878 (Fig. 2) is theQTN responsible for this phenotype as wellas for fruit sugar yield. The recent resolutionof the three-dimensional structure of Thermo-toga maritima invertase revealed a bimodulararrangement of the protein with a catalyticactive site that has a pocket topology (24).The S. pennellii Asp348 aligns with the aminoacid Tyr266 in T. maritima, which is within 10Å of the catalytic site that is likely associatedwith sucrose recognition and binding. Theresults presented in our QTL study appear tobe consistent with the crystal structure anal-ysis, thus providing a clue about how a pointmutation can alter tomato invertase kineticsand sugar yield in a quantitative way.
The present study relies on the high-resolution QTL mapping attributes of themultispecies tomato IL resource and pre-sents a zoom-in view of a QTN, from thewhole-genome perspective to a single func-tional amino acid in the crystal structure. InDrosophila, which is a model organism forthe dissection of complex traits, most of thepolymorphisms affecting quantitative vari-ation are in putative regulatory regions thattend to fractionate into multiple linkedQTL upon high-resolution analysis (25).This is in contrast to Brix9-2-5 and otherplant QTL, which in most cases maintaintheir distinct “single-factor” identity in finemapping (5). It is too early to tell whetherthe difference in the genetic architecture ofquantitative traits between Drosophila andplants reflects different biology or relatesto the amount of diversity between theparents that were used in the analyses. Thecultivated and wild species that parentedthe ILs are highly divergent in sequence,but more importantly in phenotype, thusproviding abundant segregation for natural-ly selected variation affecting yield, mor-phological, and biochemical traits. For ILs,chromosome substitution strains (4), andother permanent populations, resource con-struction must be followed by the muchmore daunting task of phenotyping of dif-ferent traits over varied environments and
Fig. 3. Alignment of the Brix9-2-5 peptide sequence (28). (A) Tomato species Brix9-2-5 allelicseries. The relevant three amino acid substitutions between S. lycopersicum and S. pennellii are inbold. The phenotypic effect (�, present; –, absent) of the wild species’ alleles located along theshort arm of chromosome 9 on B is indicated on the right and is based on multiple-site testings ofadvanced backcross populations (18–21). (B) Sequence alignment of the protein region spanningBrix9-2-5 in several plants showing a conserved aspartate (D).
Table 1. IL9-2-5 effects on invertase activity inflowers. Invertase activity (mmol reducing sugarsper gram fresh weight per hour) was determined inthe insoluble fraction of ovaries before anthesisand during anthesis. Mean values were calculatedbased on five replicates of 10 ovaries each (�TE).
Genotype/stageCell wall invertase activity
Preanthesis Anthesis
M82 9.5 � 4.1 20.4� 4.1IL9-2-5 32.0 � 4.1 63.2 � 4.1
Fig. 4. Biochemical analysis of invertase-deficient yeast complemented by LIN5 alleles.Kinetic analysis of the LIN5 enzymes from yeaststrains overexpressing the proteins from S. ly-copersicum (LIN5lyc-E), IL9-2-5 (LIN5pen-D), andmutated S. lycopersicum (LIN5lyc-D). Acid inver-tase activity was measured in soluble fractionsof a 3-day yeast culture with different sub-strate (sucrose) concentrations. Each point rep-resents a mean of four replicates.
R E P O R T S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1788
genetic backgrounds (26, 27). Such QTLdatabases, housing hundreds of phenotypesmeasured on a common set of ILs, will leadto association between seemingly unrelatedtraits and allow us to explore higher levelorganization of complex phenotypes andthe role of pleiotropy.
References and Notes1. T. F. Mackay, Annu. Rev. Genet. 35, 303 (2001).2. D. Zamir, Nature Rev. Genet. 2, 983 (2001).3. Y. Eshed, D. Zamir, Genetics 141, 1147 (1995).4. J. B. Singer et al., Science 304, 445 (2004).5. I. Paran, D. Zamir, Trends Genet. 19, 303 (2003).6. M. Koornneef, C. Alonso-Blanco, D. Vreugdenhil,Annu. Rev. Plant Biol. 55, 141 (2004).
7. S. El-Din El-Assal, C. Alonso-Blanco, A. J. Peeters, V.Raz, M. Koornneef, Nature Genet. 29, 435 (2001).
8. J. N. Maloof et al., Nature Genet. 29, 441 (2001).9. A. Gur, D. Zamir, PLoS Biol. 2, e245 (2004).
10. S. Knapp, L. Bohs, M. Nee, D. M. Spooner, Comp.Funct. Genomics 5, 285 (2004).
11. Y. S. Liu et al., Plant Biotech. J. 1, 195 (2003).12. A. Gur, Y. Semel, A. Cahaner, D. Zamir, Trends Plant
Sci. 9, 107 (2004).13. E. Fridman et al., Mol. Genet. Genomics 266, 821
(2002).14. E. Fridman, T. Pleban, D. Zamir, Proc. Natl. Acad. Sci.
U.S.A. 97, 4718 (2000).15. E. Fridman, D. Zamir, Plant Physiol. 131, 603 (2003).16. K. Koch, Curr. Opin. Plant Biol. 7, 235 (2004).17. G. Q. Tang, M. Luscher, A. Sturm, Plant Cell 11, 177
(1999).18. L. F. Stam, C. C. Laurie, Genetics 144, 1559 (1996).19. S. D. Tanksley et al., Theor. Appl. Genet. 92, 213
(1996).20. D. Bernacchi et al., Theor. Appl. Genet. 97, 170
(1998).21. T. M. Fulton et al., Theor. Appl. Genet. 100, 1025
(2000).22. A. Frary, T. M. Fulton, D. Zamir, S. D. Tanksley, Theor.Appl. Genet. 108, 485 (2004).
23. D. Gozalbo, S. Hohmann, Curr. Genet. 17, 77 (1990).24. F. Alberto, C. Bignon, G. Sulzenbacher, B. Henrissat,M. Czjzek, J. Biol. Chem. 279, 18903 (2004).
25. T. F. Mackay, Curr. Opin. Genet. Dev. 14, 253 (2004).
26. H. Ge, A. J. Walhout, M. Vidal, Trends Genet. 19, 551(2003).
27. N. Freimer, C. Sabatti, Nature Genet. 34, 15 (2003).28. Single-letter abbreviations for the amino acid resi-
dues are as follows: A, Ala; C, Cys; D, Asp; E, Glu; F,Phe; G, Gly; H, His; I, Ile; K, Lys; L, Leu; M, Met; N, Asn;P, Pro; Q, Gln; R, Arg; S, Ser; T, Thr; V, Val;W, Trp; andY, Tyr.
29. We thank L.Willmitzer for support and discussions, T.Pleban for the technical assistance, A. Sturm for theinvertase antibody, A. G. Heyer for advice on yeasttransformations, and D. Spooner for updating thenew tomato taxonomy. We are grateful to Y. Eshed,E. Pichersky, and S. Wolf for the helpful discussions.This research was supported by a grant from theGerman-Israeli Cooperation Project (DIP).
Supporting Online Materialwww.sciencemag.org/cgi/content/full/305/5691/1786/DC1Materials and MethodsFigs. S1 to S5References
18 June 2004; accepted 5 August 2004
R E P O R T S
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1789
Bookmark the custom AAAS online bookstore at Barnes & Noble.com(www.aaas.org/bn) and get great deals on all your books:
• Save an additional 5% off the already great prices on every product — including all textbooks
• Stay up-to-date with our Science Editor’s and AAAS’srecommendations
• Find out about special sales, promotions, and other moneysaving offers
You'll also find the huge selection, award-winning customer service,and low prices you've come to expect from Barnes & Noble.com.
Bookmark the AAAS Bookstore and start saving NOW!www.aaas.org/bn
SPECIAL SAVINGS FOR AAAS MEMBERS
Co-ChairmenAllen Spiegel, M.D.Director, National Institute of Diabetes &Digestive & Kidney Diseases, NationalInstitutes of Health
Walter Cohen, D.D.S.Chairman of the Board, National DiseaseResearch InterchangeChancellor Emeritus, Medical College ofPennsylvania, Hahnemann University
Keynote Speaker
James Shapiro, M.D., Ph.D.Director, Clinical Islet TransplantProgram, University of Alberta, Edmonton
Historic Perspective/Islet Cell Transplant
Paul E. Lacy, M.D., Ph.D.Chairman Emeritus,Department ofPathology, University of Washington
For conference information and to make a reservation, visit the NDRIweb site at www.ndriresource.org. Reserve now, limited seating available.
December 1 - 2, 2004Rittenhouse Hotel
Philadelphia, PA
Join our roundtable discussions with these scientists:
“Obstacles and Challenges to Islet Cell Transplant”
Co-Chair: Paul Robertson, M.D.Chief Executive Officer, Pacific Northwest Research InstituteCo-Chair: Camillo Ricordi, M.D.Scientific Director and Chief Academic Officer,Diabetes Research Institute, University ofMiami School of Medicine
“Alternative Paths to the New Therapy,the Face of the Future”
Chair: Ali Naji, M.D., Ph.D.Professor of Surgery, University of Pennsylvania
Presentations:
Paul E. Lacy Medal for “OutstandingScientific Achievement” toJames Shapiro, M.D., Ph.D.Presenter: Lee DucatPresident, NDRI
Islet Cell Transplant, Prelude to the FutureIn Honor of Paul E. Lacy in his 80th Year
www.sciencemag.org SCIENCE VOL 305 17 SEPTEMBER 2004 1791
3-D CULTURE MATRIXCultrex 3-D Culture Matrix RGFBME is the first basement mem-brane extract produced and quali-fied specifically for use in three-dimensional (3-D) culture studies.
It provides the foundation for cells to grow in three dimensions,allowing for the formation of structures in vitro. To provide astandardized basement membrane extract for use in 3-Dcultures, a special process is employed to reduce growth factorsand provide material at a standard concentration of about 14mg/mL. 3-D cell culture is an innovative approach to modelingthe morphological effects of early oncogenesis in 3-D environ-ments. Healthy cells undergoing differentiation exhibit a struc-tured, polarized morphology that is critical for cellular formationand function. During carcinoma development, cell cycle controlsassociated with cellular development, proliferation, and deathare lost, and, as a result, these structures are disrupted. In effect,the morphology of these structures can be used as a measure tostudy factors in early carcinoma development.
SERUM BIOMARKER CHIPThe serum biomarker chip is an af-fordable research tool to profileserum biomarkers and discriminatestages of disease progression. Thedetection of over- and under-abun-
dant serum biomarkers has value in cancer research. The SerumBiomarker Chip enables proteomics researchers to profile andpattern the molecular signature of human serum.
The chip addresses the need for high-throughput technologiesused to study and develop a range of research applications includ-ing risk stratification, disease prognosis, and drug eligibility, pre-dictions of safety, and efficacy. The chip contains 120 differentantibodies spotted on FAST slides, a widely used protein microar-ray surface. It is the first high-density antibody chip specific toserum biomarkers related to human cancers of every major organ.
FIXATION AND DEAD CELLDISCRIMINATION KITThe MACS Fixation and Dead CellDiscrimination Kit for advancedflow cytometry allows fixation ofcells to be combined with dead cell
exclusion. Dead cells can be stained irreversibly, so the samplecan be fixed and the dead cells can be excluded from flow-cyto-metric analysis. The kit provides several advantages, includingstorage of cell samples for up to 24 hours, reduced biohazard ofinfectious samples, and performance of rare cell analysis.
EXPANDED MASS SPECTROMETERTwo electrochemical (EC) systems,the Coulochem CoulArray and theDiscovArray, can be used in conjunc-tion with a mass spectrometer (MS)to expand the number and types of
molecules for analysis. The EC systems can be integrated into virtu-ally any MS or liquid chromatography/MS system to oxidize andionize many different types of compounds. Typical ionization
sources are often not enough to ionize “difficult” compounds foranalysis. This necessitates a lengthy and risky derivatization processin order to analyze the compound. Another problem is that themass spectrometer may be unable to analyze every component ofa sample containing multiple compounds. To address these issues,these EC systems make use of simple oxidation reactions to ionize,or otherwise oxidize, compounds to make them amenable to MSanalysis. The systems can be used in-line with the mass spectrome-ter to ionize or otherwise react poorly ionizing compounds.
TABLETOP CENTRIFUGEAvailable with quick-setting rotaryknobs or an easy-to-clean soft-touchcontrol keypad, the versatile LegendMach 1.6 is the latest model in theLegend series of tabletop centrifuges.
Refrigerated and non-refrigerated versions offer high capacities.Five interchangeable rotors offer capacities to 1.6 liters and speedsup to 15,000 rpm (24,652 × g) for versatility that makes the Mach1.6 at home in microbiology, biotechnology, pharmaceutical, clini-cal, and general laborato-ry environments. A swing-ing bucket rotor accom-modates round, square,and tissue culture buck-ets, with adapters avail-able for all popular tubesand bottles. Microplate,microliter, fixed-angle,and windshielded swing-ing bucket configurationscomplete the rotor line-up, each offering independently certifiedbiocontainment protection for samples and personnel. PatentedSMARTspin imbalance detection provides run stability for all rotorsat all speeds, and allows samples to be balanced by eye alone.
ROTARY MICROTOMEThe Leica RM2265 high-performancemicrotome is designed primarily foruse in industry and biomedical re-search. Its developers placed specialemphasis on translating the require-
ment of discriminating users and on increasing safety and reliability.The instrument housing has been adapted to modern user require-ments for enhanced ergonomy. The RM2265 includes accessoriessuch as an ergonomically integrated section waste tray and optionalgel cushions that support the user’s wrists and make long hours orroutine work much less fatiguing.While the proven precision microm-eter feed mechanism remains unchanged, the microtome base platehas been dynamically strengthened to improve the stability of the in-strument. The entire line of accessories—the knife-holder base, knifeholders, and the specimen clamping system—has been reworked.
Newly offered instrumentation, apparatus, and laboratory materials of interest to re-searchers in all disciplines in academic, industrial, and government organizations arefeatured in this space. Emphasis is given to purpose, chief characteristics, and availabil-ity of products and materials. Endorsement by Science or AAAS of any products ormaterials mentioned is not implied. Additional information may be obtained from themanufacturer or supplier by visiting www.scienceproductlink.org on the Web, whereyou can request that the information be sent to you by e-mail, fax, mail, or telephone.
N E W P R O D U C T STrevigen
For more information 800-873-8443
www.trevigen.comwww.scienceproductlink.org
LeicaFor more information +49 (0) 6224/143 233
www.leica-microsystems.comwww.scienceproductlink.org
KendroFor more information
828-658-2856www.kendro.com
www.scienceproductlink.org
ESAFor more information
978-250-7000www.esainc.com
www.scienceproductlink.org
Schleicher & SchuellFor more information
+49 5561-791www.schleicher-schuell.de
www.scienceproductlink.org
Miltenyi BiotechFor more information
+49 2204-8306-0www. MiltenyiBiotec.com
www.scienceproductlink.org
Drug Discovery andBiotechnology Trends
special advertising section
Genomics 3:It’s a Knockdown!
In this issue:
> Gene knockout systems> siRNAs> siRNA libraries> Isolation and
characterizationof siRNA
> Transfection methodsfor cells
> Cell signaling> Target identification
and validation> Therapeutic applications
of siRNA
>> >> >>
When scientists introduce segments of double-stranded RNA into cells, the segments break up intostrands of RNA 21 to 25 base pairs in length. Those“small interfering RNA” (siRNA) strands cause RNAinterference, a natural phenomenon that blocksgenes from being expressed inside a living cell.Referred to as RNAi, the effect plays a key role inantiviral defense, gene regulation, and genomicrearrangements in plants, insects, and mammals.
Within the past few years, RNAi has taken theworld of life science by storm, becoming an essentialtool for both fundamental and applied research.“RNAi is the hottest technology in biotechnologytoday; it has the potential to revolutionize biologyresearch and drug target discovery,” says Jean-LouisRoux dit Buisson, CEO of Elchrom Scientific. “Ican’t think of a single biological area, in industry,academe, or government, that’s not using RNAi,”says David Brown, senior scientist and head of thesiRNA project group at Ambion. “I’ve heard of sev-eral instances where reviewers comment thatpapers should be validated by RNAi.” ChristopheEcheverri, lead founder, CEO, and chief scientific offi-cer of Cenix BioScience, agrees. “It’s changingeverything,” he says. “We’re seeing the beginning ofthe era of RNAi-based functional genomics.”
METHOD OF CHOICE
Jim Hagstrom, vice president of scientific opera-tions at Mirus Bio Corporation, explains whyscientists have welcomed the technology soheartily. “RNAi has become the method of choice
for looking at the cause and effect of an individualgene’s expression as it relates to other genes,” hesays. “The impact has been enormous,” adds RonHerzig of Upstate. “For the first time, scientistshave been able to determine the function of a genevery quickly. This technology made it very easy andeconomical to accomplish that.”
RNAi has developed with remarkable speed. “Thestart came in the late 1990s in a paper by Craig Melloand Andrew Fire [of the University of MassachusettsMedical School and The Carnegie Institute, respec-tively] on the use of double stranded DNA for genesilencing,” says Echeverri. “But the big explosionhappened when Tom Tuschl, then at the Max PlanckInstitute in Göttingen, Germany and now atRockefeller University, demonstrated a way tomake it work in human cells.” The emergence ofthe approach surprised much of the life sciencecommunity. “Nobody really expected that such fun-damental new mechanisms were still to be discov-ered,” says Nagesh Mahanthappa, director of corpo-rate development at Alnylam Pharmaceuticals.“We’ve probably only seen the tip of the iceberg yet.”
Suppliers of RNAi-related tools, technologies,and reagents have furthered the advance of the
m o r e > > >
With its ability to silence genes, RNA interference has made a loud
noise in life science laboratories. Researchers have started to apply it
in areas as diverse as research on cell signaling, drug discovery, and
human therapeutics. by peter gwynne and gary heebner
1793
The companies in this article were selected at random. Theirinclusion in this article does not indicate endorsement byeither AAAS or Science, nor is it meant to imply that theirproducts or services are superior to those of other companies.
This is the third of four supplements this year on genomics.The first two appeared in the 6 February and 9 April issues ofScience. The last will appear in the 22 October issue.
Drug Discovery and Biotechnology TrendsGenomics 3: It’s a Knockdown
approach. “They realized that it worked and then made it available toresearchers and drug companies by providing tools off the shelf,” saysHagstrom. “That raised awareness of the technology; it created the buzz.”
Vendors also improved the basic tools. “They have contributed mostnotably in the chemistry of siRNA. They have driven the advancement ofsiRNA’s purity, stability, and design, and have minimized off-targeteffects,” Herzig says. “The siRNA design tools available free on many aca-demic sites give you about 70 percent success,” adds Walter Tian, busi-ness director of Qiagen. “Commercial companies such as Qiagen havedeveloped much better computer-generated design algorithms that giveyou up to 90 percent efficiency.” Commercial suppliers also emphasizeuser friendliness. “They have brought a level of standardization so thatyour laboratory doesn’t have to start from scratch,” says Joel Hansen,application development director at NanoDrop Technologies.
SUPPRESSING GENES
RNAi’s value stems from its ability to suppress genes – a capability alsocalled knocking down, or silencing genes. Doing that enables scientists tofocus on the function of individual genes. RNA interference isn’t the firsttechnology to achieve that goal. Charles River Laboratories, TheJackson Laboratory, and Taconic, among other organizations, offerknockout mice, in which specific genes have been completely suppressed.ArtisOptimus supplies primary mouse embryo fibroblasts from a largevariety of knockout and transgenic mice. Altered tissue culture cells withknocked out genes are also available. And several researchers have usedantisense technology to dampen down the functions of genes.
However, RNAi shows significant advantages over those olderapproaches. Thus, while knockout systems suppress genes entirely, RNAireduces their expression level – a simpler and faster approach for basicunderstanding of gene function. On the other hand, RNAi silences genesmore effectively than antisense technology. “Antisense has never beenbroadly adopted. It’s too hard to do, it takes too long to optimize, and itcauses too many undesired side effects,” explains Tian of Qiagen. “RNAiis much more efficient than the antisense oligos in terms of gettingknockdown in vivo,” Hagstrom adds.
Bill Marshall, executive vice president research and operations atDharmacon, summarizes RNAi’s benefits. “The ease of implementa-tion, time to receive a quality answer, and the robustness of the technol-ogy are all optimal with RNAi compared with past technologies,” he says.“It’s probably the most enabling reverse genetics tool that the scientificcommunity has ever encountered.”
Methods of producing siRNAs include chemical synthesis, in vitrotranscription, digestion of long double stranded RNA (dsRNA) by a so-called dicer enzyme, and expression in cells. Each method has uniquefeatures and benefits appropriate for different scientific approaches.Chemical synthesis, for example, facilitates research that requires a large
amount of defined siRNA, while in vitro transcription methods are idealfor screening siRNA sequences or short-term studies. Digestion of longdsRNA produces a heterogeneous population of siRNAs but does notrequire the design and testing of specific siRNA sequences before hand.Expression systems allow researchers to insert antibiotic resistancemarkers that help them to select transfected cells.
KITS AND REAGENTS
Companies such as Ambion, Epicentre, and Invitrogen offer kits andreagents that permit scientists to produce their own siRNAs via whichevermethod they choose. Alternatively, they can buy siRNA for a large numberof published genes, including BRCA1, HPRT, and Lamin, from Dharmacon,Proligo, Qiagen, Stratagene, and other vendors. These suppliers notonly offer tested siRNAs; they also synthesize custom siRNA forresearchers and provide items for newcomers to the technology.
“We offer a variety of control products and starter kits for people whohave limited experience with siRNA. For example, our RNAi control kitoffers all reagents needed to set up and optimize an RNAi protocol,” saysQiagen’s Tian. The company has also extended the reach of siRNA algo-rithms. “Working in partnership with Novartis Pharmaceuticals, wehave studied design using a unique algorithm that’s different from thoseprimarily based on Tuschl’s design rules,” Tian continues. “The result ismore potent siRNA to target the genes of interest with high specificity.”
Ambion has contributed research as well as products. “We were thereat the beginning with our rapid uptake kit,” Brown says. “And ourresearch effort has allowed us to develop products in-house that permitresearchers to focus on the biology. We’re the tinkerers in the corner whocreate the protocols that enable everyone else to do the biology and getimportant insights into the science.” Now, he continues, “We pride our-selves on being a one-stop shop. We have siRNA tools that target everyknown gene in mouse, human, and rat. Our delivery reagents cover thebroadest spectrum of cells on the market. We’ve also developed trans-fection based reagents that enable us to get into any cell type.”
The company also offers siRNA libraries. Its Silencer Nuclear HormoneReceptor siRNA Library targets 51 human nuclear hormone receptor geneproducts, and accelerates functional analyses of this class of proteins.“It’s very effective in reducing target gene expression,” Brown says. “It’suseful in validating hits from a screening experiment.”
ISOLATION AND PURIFICATION
Traditional procedures for isolating RNA generally focused on largerRNAs, such as transfer, ribosomal, and messenger RNA. Isolating siRNA,by contrast, demands a method that works well with smaller RNAs.Scientists must also ensure that all solutions and materials involved inpreparing siRNA are free of the RNase enzyme, which is not a concernwhen isolating DNA.
Elchrom Scientific has introduced a purification method that gives ayield of typically 60 percent of an incoming full length oligo at 98 percentpurity within three hours. “It’s a nontoxic hydrogel-based technology thatinvolves electrophoresis followed by a revolutionary elution technology,”says Anatoli Tassis, Elchrom’s manager of oligo purification. “We’ve doneit so far at a research scale,” says Roux dit Buisson. “But we’re workingwith a partner to get it up to industrial scale.”
1794
special advertising section
Drug Discovery and Biotechnology Trends OnlineNeed to refer to this article or others in this series? Want a colleagueto read it? Visit www.science-benchtop.org. Benchtop givesyou access to this article as well as past special advertising sections.
Need instant product information? Visit http://scienceproductlink.org.
m o r e > > >
At SANYO we’re introducing a whole new generation oflife science laboratory products and professional appliancesdeveloped to meet new standards in performance, accuracyand biosecurity.
As one of the world’s largest and most innovative corporations, SANYO continues to explore and shareunique technologies acquired from internal resources andglobal consumer and industrial markets, while testingand applying our ideas with creativity and confidence.
As a result, SANYO biomedical products deliver realsolutions in inventory efficiency, intelligent controls,
refrigeration, compliance, data communications,ergonomics, energy management and more.
Depend on SANYO integrated product solutions to shape the future, one lab at a time.
For your free North American Product Guide go to www.sanyobiomedical.com, call SANYO toll-free800-858-8442 or contact your local SANYO SalesRepresentative.
Products shown Left to Right: CO2 Incubator, -86Cº Freezer,Portable Autoclave, -30C º Freezer and Laboratory Refrigerator
Products Designed To Shape the Future
SANYO Sales and Supply Co. • 1062 Thorndale Avenue, Bensenville, IL 60106 USA • Toll-Free USA 800-858-8442 • Fax 630-238-0074 • www.sanyobiomedical.comSANYO Canada, Ltd. • 300 Applewood Crescent, Concord, Ontario L4K 5C7 • 416-889-3107 • FAX 416-889-3117
© 2003 OW6966US
I n c u b a t o r s , U l t r a - L o w a n d C r y o g e n i c F r e e z e r s ,
B i o m e d i c a l R e f r i g e r a t o r s , A u t o c l a v e s , E n v i r o n m e n t a l C h a m b e r s
Detecting and measuring quantities of siRNA presents another prob-lem, because their small sizes prevent their amplification via the favoredreverse transcriptase PCR procedure. Most researchers use Northernblots with polyacrylamide gel electrophoresis for this process.Companies such as GE Healthcare (formerly Amersham Biosciences)and Bio-Rad Laboratories offer instruments and reagents to detectand quantitate RNA and other biological molecules.
MEASUREMENT AND TRANSFECTION
NanoDrop Technologies offers a unique spectrophotometer to measurevery small sample volumes by eliminating the need for cuvettes. It canmeasure concentrations of RNA as low as two nanograms per microliterusing a single microliter of sample. “The design is based on the principleof surface tension, which retains the one-microliter sample in placebetween two optical fibers,” Hansen explains. “So you have a direct con-tact between the sample and the optics without any external sample cap-ture mechanism. With its shorter path length of 0.2 millimeters, thespectrophotometer permits accurate measurement of samples 50 timesmore concentrated than conventional methods.” Since the path lengthdoes not depend on the exact volume, the instrument offers excellentaccuracy while conserving precious samples.
Once purified, siRNA must be inserted into a living cell to examine itseffects on the cell. Some transfection methods accommodate specific celltypes; for example, scientists can transfect a plant cell by literally shoot-ing siRNA from a gun through its rigid cell wall. More sensitive cellsrequire more delicate treatment. Amaxa and Gene Therapy Systemsoffer such methods as electroporation, viral-mediated transfection, andchemical transfection with cationic liposomal and polyamine basedagents for mammalian cells. Mirus Bio, which specializes in technologiesfor delivering and labeling genes, has developed the first broad spec-trum, siRNA-specific transfection reagent, which it calls TransIT-TKO. Thisreagent facilitates highly efficient siRNA transfection with significantlyless cell damage than that caused by cationic-liposome based transfec-tion reagents. “We developed it so that scientists could use modestamounts of siRNA, which is costly, and have the ability to knock out thespecific gene they want to,” Hagstrom says. The company’s most recentproduct, the TransIT-siQUEST transfection reagent, complements TKO byboosting the efficiency of knockdowns for which TKO is not maximallyeffective. “Our goal is to attain the highest knockdown efficiencies – inthe 80 or 90 percent range,” Hagstrom says.
VARIETY OF APPLICATIONS
Gene silencing mediated by siRNA has a wide variety of applications.Prominent examples include research on cell signaling, drug discoveryand validation, and human therapeutics.
Upstate offers siRNA/siAb assay kits for studying genes involved in cellsignaling. The kits supply what is necessary to knock down a targetedmessage and determine the level of the knockdown. The kits resultedfrom a collaboration with Dharmacon. “Dharmacon contributes the siRNAdesign and chemistry and we contribute the antibody and cell lysate com-ponents,” Herzig says.
Each kit guarantees the knockdown of the targeted mRNA by at least75 percent within 24 hours and allows scientists to detect the targeted
protein in a Western blot. Dharmacon designed its reagents to make thesiRNA more effective in its ability to knock down the targeted messageand to reduce the chances of any off-target effects mediated by siRNA.“Our reagents have a high reliability to function in assays,” Marshallsays. “We want to make sure that anyone who does an RNAi experimentwith an interesting outcome will be able to correlate the knocked downgene with the outcome.”
Cenix Bioscience, meanwhile, has developed expertise with RNAi-based screens that can be carried out in several model organisms,including C. elegans and Drosophila cells, to identify new disease-rele-vant genes. “By doing this we can start looking at the idea of RNAi-basedphenotypic profiling of genes that we call phenoprinting,” Echeverri says.“That means that we can go through small, medium, and large collec-tions of genes, up to an entire genome, and identify therapeutically rele-vant genes. We can also use the approach to determine how drugs work,by combining drug treatments with RNAi screens.” The company’s spe-cialization in the high throughput application of RNAi allows it to savetime and reduce costs in carrying out even the most complex and large-scale, cell based validation projects. “Most of our work now is in culturedcells,” Echeverri says. “But we look forward to doing some in vivo in ani-mals, although obviously not as high throughput.”
1798 m o r e > > >
Four Conferences in One
Individuals who register for Assays & Cellular Targets (ACT), an inter-national event that will take place in the Sheraton San Diego Hotel& Marina for four days starting on October 18, will have the chanceto attend four international conferences under a single roof. Theevent, organized by IBC Life Sciences, will feature the ninthannual conferences on assay development and on G-protein cou-pled receptors (GPCRs), the fourth conference on cell based assaysand screening, and the third conference on ion channel drug targets.
The conference on assay development will provide updates onnew assay technologies and creative assay strategies, and will out-line anticipated developments in the field. The GPCR meeting willdetail advances in such areas as dimerization, activation, signaltransduction, functional validation, and modulation. Individuals whoattend the meeting on cell based assays and screening will learnabout high content screening, applications of cell based assays toabsorption, distribution, metabolism, excretion and toxicology, andstrategies for target validation and lead optimization. And attendeesat the event on ion channel drug targets will be exposed to efforts tomaximize the therapeutic potential of ion channels.
Among them, the four conferences will feature more than 100speakers and a unified exhibit hall. Special events include themedluncheon discussions, a poster networking area, and scientificposter award presentations.
www.IBCLifeSciences.com/ACT
Drug Discovery and Biotechnology TrendsGenomics 3: It’s a Knockdown
special advertising section
GEArray DNA Microarrays are ideal tools for yourgene expression studies. Each GEArray includesa thoroughly researched set of relevant, pathway-or disease-focused genes. GEArray is the mostsensitive microarray. It is easy to use and cost effective.Choose from our comprehensive list of standard
GEArrays covering applica-tions including cancer,immunology, apoptosis,cell signaling and more. Ororder a custom GEArraytailored to your specialapplication. GEArrays arepriced from $50/array.
Pathway Focused GEArray® DNA Microarrays Focus on your target. Catch the most relevant genes.
888-503-3187 (USA) 301-682-9200
Let us show you what focused microarraytechnology can do for you. Find your pathwayfocused microarray at www.SuperArray.com.
sensitivef l e x i b l e
focused
Pathway-Centric Tools and Technology™
Pathway focused design: includes 100–500
relevant, pathway specific genes.
Sensitive and reproducible: requires as little as0.1 µg total RNA
Open platform: Designed for use in any mole-cular biology lab; a thermal cycler, hybridizationoven and X-ray film or CCD imager system arerequired equipment. Can be detected by eitherchemiluminescence or fluorescence.
Complete microarray hybridization/analysis service also available.
POTENTIAL DRUG CANDIDATESScientists can synthesize small interfering RNAs chemically in the lab andthen introduce them into cells, thereby opening up great possibilities forusing siRNAs as potential drug candidates. Such drugs have severalpotential advantages over small molecules. For example, they can targetvirtually any protein without the class restrictions common to some smallmolecule drugs. They can also simplify the process of drug discovery, asthey may not require the extensive lead optimization seen with small mol-ecule drugs. Pharmaceutical companies, including AcuityPharmaceuticals and Sirna Therapeutics, are also betting on siRNAfor their therapeutic programs.
Two years ago Alnylam, named for the bright star in the center ofOrion’s belt, became the world’s first company focused on RNAi thera-peutics. “The major focus of our internal R&D program is to impart chem-ical modifications to RNAs to give them desir-able attributes like increased chemical stability– siRNAs being fragile molecules that don’t lastlong in the bloodstream,” Mahanthappaexplains. “We have explored chemical modifi-cations that improve siRNA’s stability and willincrease the probability that the cells we wantto treat will see the molecule and turn the geneoff.” The company is also working on covalentmodifications of siRNA to increase its half-lifewhile circulating in the bloodstream and toincrease its cellular uptake.
Mahanthappa sees two broad categories ofdisease that RNAi could treat. “We have sys-temic RNAi in which we’ll inject the siRNA intothe bloodstream,” he says. “And there’s directRNAi in which we’ll administer siRNA directlyinto the region of the body affected by the dis-ease – such as the appropriate part of thebrain for Parkinson’s disease.”
AGGRESSIVE THERAPYThe most promising therapeutic application ofthe technology relies on the direct approach.“We aim to inhibit the growth of new bloodvessels in the retina that cause macular degen-eration,” Mahanthappa explains. “We’ll injectsiRNA into the vitreous humor and expect it tofind its way to the retina.” Alnylam has takenan aggressive approach to the therapy. “It’sour goal to be in the clinic with macular degen-eration by 2005,” Mahanthappa asserts.
For the alterative approach, he continues,“The liver is a great locus for systemic treat-ments. We think that therapeutic possibilitiesinvolve the regulation and treatment of variousblood disorders and hepatitis B and C.” Otherconditions that could benefit from RNAi ther-apy include metabolic diseases such as dia-
betes, high cholesterol, and obesity; viral diseases; autoimmune dis-eases; and cancer.
The relative simplicity of using siRNA for gene silencing has persuadedmany researchers to start using this new research tool. Suppliers havedeveloped a significant offering of tested siRNAs and siRNA libraries, aswell as kits and reagents for research use. And biopharmaceutical com-panies are exploring the tool for therapeutic use. RNA interference hasgenerated more excitement and activity in a shorter time than mostadvances in research technology. Scientists will soon see what potentialthis new tool can bring to genomics, cell biology, and medicine.
1801
special advertising section
Peter Gwynne ([email protected]) is a freelance science writer based on Cape
Cod, Massachusetts, U.S.A. Gary Heebner ([email protected]) is a mar-
keting consultant with Cell Associates in St. Louis, Missouri, U.S.A.
Drug Discovery and Biotechnology TrendsGenomics 3: It’s a Knockdown
Dharmacon, Inc., siRNA kits andreagents, www.dharmacon.com
Elchrom Scientific AG, siRNA kitsand reagents, www.elchrom.com
Epicentre Technologies,siRNA kits and reagents, www.epicentre.com
GE Healthcare (formerlyAmersham Biosciences),instruments and reagents,www.amershambiosciences.com
Gene Therapy Systems, Inc.,transfection reagents,www.genetherapysystems.com
IBC Life Sciences, scientificconference organizer,www.IBCLifeSciences.com/ACT
Invitrogen Corporation,siRNA kits and reagents,www.invitrogen.com
The Jackson Laboratory,knockout mice and services,www.jax.org
Mirus Bio Corporation,siRNA kits and reagents,www.mirusbio.com
NanoDrop Technologies, Inc.,micro-volume spectrometers,www.nanodrop.com
Novartis Pharmaceuticals,pharmaceutical company,www.novartis.com
Proligo, Inc., siRNA, www.proligo.com/splash
Qiagen GmbH, instruments andreagents, www.qiagen.com
Sirna Therapeutics,biotechnology company,www.sirna.com
Stratagene, siRNA, www.stratagene.com
Taconic, knock-out mice and services, www.taconic.com
Upstate, siRNA kits and reagents,www.upstate.com
Dharmacon, Inc., synthetic siRNA and customRNA oligos. 303-604-9499, www.dharmacon.com
Quantum Dot Corporation, quantum dotsused for the detection of nucleic acids andproteins. 510-887-8775, www.qdots.com
SANYO Sales & Marketing Corporation /SANYO Electric Biomedical Co., Ltd.,constant temperature equipment (incubators,ovens, refrigerators, and freezers).www.sanyo-biomedical.co.jp
SuperArray Bioscience Corporation,pathway-focused kits, including gene arrayproducts, RNA interference products, and PCRproducts. 301-682-9200, www.superarray.com
TAKARA BIO INC., kits and reagents formolecular biology research, including genomicsand proteomics. +81 77 543 9254, www.takara-bio.co.jp/english
A D V E R T I S E R S
Acuity Pharmaceuticals,pharmaceutical company,www.acquitypharma.com
Alnylam Pharmaceuticals,RNAi-based biopharmaceuticalcompany, www.alnylam.com
Amaxa Biosystems, transfectionreagents, www.amaxa.com
Ambion, Inc., siRNA kits andreagents, www.ambion.com
ArtisOptimus, Inc., knockoutmouse embryo fibroblasts,www.artisoptimus.com
Bio-Rad Laboratories,instruments and reagents,www.expressionproteomics.com
Cenix BioScience GmbH,siRNA-based target discoveryand validation services,www.cenix-bioscience.com
Charles River LaboratoriesInternational, Inc.,knockout mice and services,www.criver.com
F E A T U R E D C O M P A N I E S
POSTDOCTORAL FELLOWSHIP PROGRAMInstitut Pasteur, Paris, France
Founded in 1887 by Louis Pasteur and located inthe heart of Paris, the Institut Pasteur is one of theworld’s leading private research organizations. ThePasteur Foundation of New York is seeking outstand-ing Fellowship Applicants who are open to an inter-national laboratory experience. Candidates may applyto any laboratory within the 12 departments: Struc-tural Biology and Chemistry, Microbial Pathogenesis,Parasitology, Immunology, Structure and Dynamicof Genomes, Cell Biology and Infection, Develop-mental Biology, Molecular Medicine, Fundamentaland Medical Microbiology, Virology, Neuroscience,and Ecosystems and Epidemiology of Infectious Dis-eases.
Open only to U.S. citizens. Fellowships are $60,000per year for three years ($45,000 stipend plus$15,000 bench fees). Application deadline: February4, 2005. For details, please visit website: http://www.pasteurfoundation.orgore-mail:[email protected].
POSTDOCTORAL POSITIONUniversity of Vermont College of Medicine
NeuroscienceBurlington, Vermont
NIH-funded Postdoctoral position to study mech-anisms underlying lower urinary tract dysfunction fol-lowing spinal cord injury or bladder inflammation.The roles of neurotrophic factors in injury/dysfunc-tion/development are investigated with a multidisci-plinary approach that includes: anatomical tracing,immunostaining, electrophysiology, biochemical,and molecular assays. Previous experience in several ofthese approaches is required. Applicants must havestrong motivation and excellent communicationskills. Funding is available for at least two years. Ap-plicants should send curriculum vitae, bibliography,and names and addresses of three references to:Margaret A. Vizzard, Ph.D., and Gary M. Mawe,Ph.D., University of Vermont, Department ofAnatomy and Neurobiology, D-411 Given, Burl-ington, VT 05405; telephone: 802-656-3209;e-mails: [email protected] and [email protected].
POSTDOCTORAL FELLOWNEUROPHYSIOLOGY
The Neurosciences InstitutePosition available immediately to study neural sub-
strates underlying navigational abilities and goal-directed behavior of rodents. Experiments involveelectrophysiological measurements of activity pat-terns within the frontal and parietal cortices and thehippocampus of behaving animals. A recently devel-oped paradigm also allows for the study of neuronalactivity in behaving mice lacking dopamine receptors.Experience with behavioral paradigms involving nav-igation, multiple single unit recordings, and/or anal-ysis of electrophysiological data is preferred. Send cur-riculum vitae, statement of research interests, andnames of three references to: Douglas Nitz, Ph.D.,The Neurosciences Institute, 10640 John JayHopkins Drive, San Diego, CA 92121. E-mail:[email protected].
POSTDOCTORAL POSITION: A positionfunded by the American Heart Association is availableto study the role of protein tyrosine phosphatases onneointima formation in vascular injury. Our projectaddresses basic science questions but also has rele-vance to clinical problems. Experience in rat andmouse surgery is essential. Competitive salaries areoffered. Please send curriculum vitae and the names ofthree references to: Dr. Yingzi Chang or Dr. AvivHassid, Department of Physiology, University ofTennessee, 894 Union Avenue, Memphis, TN38163. E-mails: [email protected] [email protected]. Fax: 901-448-7126.
POSTDOCTORAL POSITIONS in molecularmicrobiology and pathogenesis of bacterial and viralinfections. NIH-training grant Postdoctoral positionsat the University of Colorado Health Sciences Centerare available to study molecular mechanisms of bacte-rial infections (with Randall Holmes, Michael Vasil,or Martin Voskuil), viral infections (with BruceBanfield, David Barton, Thomas Campbell, Rob-ert Garcea, Donald Gilden, Kathryn Holmes,Jerome Schaack, Aleem Siddiqui, Kenneth Tyler,or Linda Van Dyk), innate immunity (with CharlesDinarello, Sonia Flores, or Andres Vazquez-Torres) or structural biology of microbial pathogen-esis (with Mair Churchill). See website: http://www.uchsc.edu/sm/microbio/ for informationabout many of our research programs. We will occupyentirely new research laboratories in November 2004.Candidates must be citizens or permanent residents of theUnited States. Candidates with Ph.D. or equivalent re-search degrees must have experience in microbiology,bacteriology, virology, immunology, molecular biol-ogy, genetics, biochemistry, cell biology, structuralbiology, or a related field. Candidates with M.D.,D.V.M., or equivalent clinical degrees must havedemonstrated competency for research related to ourprogram. Compensation is determined by NIH poli-cies. Submit curriculum vitae, bibliography, andnames of three professional references to: TrainingProgram Director, Department of Microbiology,Box B-175, University of Colorado Health Sci-ences Center, 4200 East Ninth Avenue, Denver,CO 80262. The University of Colorado Health SciencesCenter is committed to Equal Opportunity and AffirmativeAction. Individuals from underrepresented groups are encouragedto apply.
POSTDOCTORAL FELLOWSHIP INTROPICAL FOREST ECOLOGY
Center for Tropical Forest Science-ArnoldArboretum Asia Program
of the Smithsonian Tropical Research InstituteThe Center for Tropical Forest Science-Arnold Ar-
boretum (CTFS-AA) Asia Program coordinates a net-work of long-term research programs in the tropicalforests of eight Asian countries. A Postdoctoral Fel-low is sought in forest ecology and the evolution andbiogeography of forest communities. Strong analyti-cal background preferred; established record of re-search and scholarly publication in tropical forestecology and/or evolution required. Field experiencenot essential. Positions based at Harvard University.Send curriculum vitae and names of three referencesto: Stuart Davies, CTFS-AA Asia Program, TheArnold Arboretum, Harvard University, 22 Di-vinity Avenue, Cambridge, MA 02138, U.S.A.E-mail: [email protected]. The Arnold Ar-boretum of Harvard University and SmithsonianTropical Research Institute are Equal Opportunity/Affir-mative Action Employers.
POSTDOCTORAL FELLOWSHIP, CanadianInstitute of Health Research (CIHR) Group in Skel-etal Development and Remodeling, The University ofWestern Ontario, London, Canada; Ion channels inosteoclasts will be studied using patch clamp, fluores-cence, and molecular approaches. Applicants shouldhave a Ph.D. or equivalent training in biophysics,physiology, or cell biology with experience in electro-physiology. Send curriculum vitae, one-page state-ment of research interests and goals, and names ofthree references to: Drs. Stephen Sims and JeffreyDixon at e-mail: [email protected]. Forinformation, visit website: http://www.med.uwo.ca/research/skeletal-web/.
POSTDOCTORAL/RESEARCH ASSOCI-ATE POSITION for a Ph.D. or equivalent to per-form studies on the involvement of peptidases in betaamyloid metabolism and Alzheimer’s disease. Sendcurriculum vitae and names of three references to:Dr. Louis Hersh, Department of Molecular andCellular Biochemistry MS607, University of Ken-tucky, Lexington, KY 40536-0298. An AffirmativeAction/Equal Opportunity Employer.
POSITIONS OPEN POSITIONS OPEN
17 SEPTEMBER 2004 VOL 305 SCIENCE Science Careers www.sciencecareers.org1802
Classified AdvertisingFor full details on advertising rates,deadlines, mechanical requirements,and editorial calendar go towww.sciencecareers.organd click on How to Advertiseor call one of our representatives.
UNITED STATES & CANADA
E-MAIL: [email protected]: 202-289-6742Jill Steinberg(CT, DE, DC, FL, GA, MD, ME, MA, NH,NJ, NY, NC, PA, RI, SC, VT, VA)PHONE: 914-834-8733Kristine von Zedlitz(AK, AR, CA, CO, HI, ID, IL, IA, KS, LA,MN, MO, MT, NE, NV, NM, ND, OK,OR, SD, TX, UT, WA, WI, WY )PHONE: 415-956-2531Beth Dwyer – Internet Sales Manager(AL, IN, KY, MI, MS, OH, TN, WVand Internet Sales)PHONE: 202-326-6534Emnet Tesfaye(Line Advertising)PHONE: 202-326-6740Daryl Anderson – Assistant SalesManager (Canada and Meetings andAnnouncements)PHONE: 202-326-6543AD MATERIALS: Send to:Science Classified Advertising,1200 New York Avenue, NW, Room 911,Washington, DC 20005
EUROPE & INTERNATIONAL
Tracy Holmes– Sales ManagerPHONE: +44 (0) 1223 326 525FAX: +44 (0) 1223 326 532E-MAIL: [email protected] StottPHONE: +44 (0) 1223 326 527Claire GriffithsPHONE: +44 (0) 1223 326 528AD MATERIALS: Send to:Science International, Advertising Dept.,Bateman House, 82–88 Hills Road,Cambridge CB2 1LQ, United Kingdom
To subscribe to Science:In U.S./Canada call 202-326-6417or 1-800-731-4939In the rest of the world call+44 (0) 1223 326 515Science makes every effort to screen our ads foroffensive and/or discriminatory language. However, theremay be occasions when we fail to catch such ads, andwe encourage our readers to alert us to any ads thatthey feel are discriminatory or offensive.
advertising supplement
Success Factors for Postdocs
Ensuring a Fruitful FellowshipA survey sponsored by Science Careers reveals the factors that past
and present postdocs regard as most critical to the success of their
fellowships. BY P E T E R G W Y N N E
What factors have the most influence on the success of a postdoctoral fellowship? In an onlinesurvey sponsored by Science Careers, more than 900 present and past postdocs, the majority ofthem in life science departments, ranked the importance of characteristics of principal investiga-tors (PIs), including mentoring skills, publishing records, and the laboratory environment that thePIs create, in determining the success of the postdoctoral experience. Survey respondents alsorated institutions responsible for postdocs on such factors as their ability to fund research andtheir commitment to career fairs and general job guidance.
The survey asked participants to rate the significance of a dozen specific characteristics of theirprincipal investigators or supervisors. Of those, respondents generally assigned the most signifi-cance to five factors: mentoring (which 83 percent of participants viewed as very important orextremely important); a sense of direction and vision (81 percent); the ability to obtain fundingand grants for postdoctoral work (79 percent); encouraging postdoctoral fellows to carry out andpublish research that appeals to potential employers (78 percent); and helping postdocs to net-work with the scientific community (75 percent).
Biogen Idecwww.biogenidec.com
Cornell Universitywww.cornell.edu
Harvard Medical Schoolwww.hms.harvard.edu
National Cancer Institutewww.nci.nih.gov
National PostdoctoralAssociationwww.nationalpostdoc.org
St. Jude Children’s Research Hospitalwww.stjude.org
University of California,Los Angeleswww.ucla.edu
University of Iowawww.iowa.edu
Wyeth Researchwww.wyeth.com
1803
techniques, expanding their skill sets, publishing research papers, andultimately establishing a permanent scientific career.
One survey taker defined the expectations as follows: “A successfulpostdoctoral experience would include gaining useful technical andintellectual experience by which to broaden future career opportuni-ties. This is achieved by interaction with a PI who is dedicated to bothquality research and developing the postdoctoral candidate for futurecareer opportunities. Interaction with fellow postdocs and scientists isalso an essential component of a successful postdoc experience.”Another postdoc put it rather more philosophically: “A successful expe-rience must be one that fosters independence, provides a strong foun-dation in the area of study, and promotes a continuing relationshipwith the postdoctoral mentor.” Another individual summarized the sit-uation succinctly: “The postdoctoral experience should be viewed as anapprenticeship with the purpose of gaining scientific, technical, andother skills that advance the postdoc’s professional career.”
Current postdocs focused more on the activities with which theywere involved at the time of the survey, while individuals who had com-pleted their fellowships took a longer view, emphasizing to a greaterextent the need to establish a career path and to develop networks andrelationships with scientific colleagues. Scientists who had completedtheir fellowships also had more realistic understanding of career oppor-tunities available to postdocs. While 58 percent of current postdocswant to obtain tenure-track academic positions, only a quarter of for-mer postdocs had managed to land that type of job. And while only 18percent of present postdocs expect to find jobs in biotechnology orpharmaceutical companies, 31 percent of former fellows actually workfor biopharmaceutical firms.
The PI’s InfluenceRespondents agree that a postdoctoral fellow’s principal investigator orsupervisor has far more influence on the success of the fellowship than theinstitution. That’s hardly surprising. Fewer than half of the survey’s partic-ipants indicated that the institution played a significant role in their choiceof location for their fellowship. Respondents predominantly see the selec-tion of their PI as the fundamental factor in the success of their fellowship.
Those conclusions confirm anecdotal findings by organizations thatfocus on the concerns of postdocs. “They are very much consistent withwhat we’ve been hearing from our members and the postdoctoral com-munity,” says Alyson Reed, executive director of the NationalPostdoctoral Association. “In particular, the mentoring theme is onethat has paramount importance.”
Supervisors of postdocs take an even stronger view of the impor-tance of choosing the right PI. Some assert that the choice has many aspects of the selection of a marriage partner. “The postdoc-supervisor relationship has to be viewed as a lifelong relationshiprather than one that lasts a few years,” says David Eisenberg, investi-gator of the Howard Hughes Medical Institute at the University ofCalifornia, Los Angeles. “I make this explicit when a new fellow joinsthe lab. I say: ‘We are linked for the rest of my life. I accept your careeras being largely my responsibility. The corollary is that you have towork productively in the crew to make discoveries, write effectivepapers, meet people, and communicate well.’ As a supervisor I canwarn them of problems in the way they want to go.”
The choice of institution obviously has some impact on a postdoc-toral experience. Academic organizations, in particular, have recentlystarted to realize that they have an obligation to help school their post-doctoral fellows. “For years universities didn’t pay attention to postdocsat all, even though they are the next generation of professors,” saysKevin Campbell, an investigator for the Howard Hughes MedicalInstitute and professor and interim head of physiology and biophysicsat The University of Iowa. “But there’s a lot that universities can do tobetter support their postdocs, such as giving them opportunities toteach and helping them with long-term career plans.”
This supplement will detail the methodology and results of the sur-vey. It will feature comments from survey takers, on an anonymousbasis. And, it will include the observations of individual PIs whom sur-vey participants nominated as being among the best in ensuring effec-tive fellowship experiences for their postdocs.
Methodology and ResultsScience Careers surveyed members of the American Association for theAdvancement of Science, which publishes this magazine, and readersof Science. Because other organizations have recently carried out theirown studies of postdocs, the team limited the number of potential par-ticipants to 10,000 Ph.D.s in the United States who were participatingin or had completed postdoctoral fellowships. An online invitation toparticipate issued in March 2004 resulted in 932 completed surveys, asignificant proportion for this type of endeavor.
Wherever they received their training, respondents to the survey hadsimilar expectations for their time as a postdoctoral fellow. The largemajority expected their experience to include learning new research
1804 continued >>
Success Factors for Postdocs
advertising supplement
Success Factors for Postdocs
Between 55 percent and 66 percent of survey participantsconsidered the group of factors in this tier as very orextremely important.
� Advancement Opportunities/ � Quality of LifeCareer Options � Training
� Work Culture/Environment � Communication� Compensation and Benefits
At least 75 percent of survey participants regarded the groupof factors in this tier as very or extremely important.
� Mentoring � Employer/Situation
� Direction and Vision � Networking
� Funding/Grants
Tier Two
Tier One
1806 continued >>
Success FactorsWhat factors play the strongest roles in determining the success of fel-lowships as defined by the past and present postdocs? Organizers of thesurvey provided a choice of 12 specific characteristics controlled by thefellow’s principal investigator and five determined to some extent by theinstitution that hosts the postdoc. Respondents were asked to rate thosecharacteristics’ contributions to successful fellowships on a sliding scale.
Respondents’ rankings of the dozen factors under the control of PIs fit-ted neatly into three separate tiers. The first tier contains five character-istics that at least three quarters of the respondents consider very impor-tant or extremely important to their success as postdoctoral fellows: men-toring, direction and vision, funding and grants, assistance in findingemployment, and networking. The second tier, which 55 percent to 66percent of respondents rate as very important or extremely important,consists of advancement opportunities and career options; the work andculture environment of the PI’s laboratory; compensation and benefits;quality of life; training; and communication between PI and postdoc. The
final tier contains a single factor: Just 34 percent of the sample rankedthe influence of a postdoc’s spouse or partner as very important orextremely important. That doesn’t come as a surprise; many respondentsdo not have spouses or partners who might influence their decisions.
The institution plays a much smaller role in postdocs’ criteria for thesuccess of their fellowships. Even the highest rated factor controlled bythe institution – funding and grants, viewed as very important orextremely important by just 63 percent of survey takers – would nothave reached the top tier of characteristics determined by principalinvestigators. Of the other institutionally influenced factors, compensa-tion and benefits garnered a 48 percent ranking as very important orextremely important, quality of life 44 percent, networking 36 percent,and spouses or partners just 28 percent.
Other factors that participants in the survey regarded as importantto successful postdoctoral experiences include transitioning into a per-manent career, networking and collaborating with other scientists, andteamwork and other interpersonal skills. Individuals also point out the
Top Principal Investigators by Success Factor
Mentoring� Joseph Bonventre* Harvard-MIT Division of Health Sciences Brigham and Women's Hospital, Boston, MA
and Technology and Department of Medicine Harvard Medical School and MIT� Kathryn Holmes Department of Microbiology University of Colorado Health Sciences Center Denver, CO� Richard Lyttle* Women's Health & Bone Discovery Wyeth Research Collegeville, PA
Direction and Vision� Kevin Campbell* Departments of Physiology and University of Iowa College of Medicine Iowa City, IA
Biophysics; Neurology� Richard Dixon Plant Biology Division Samuel Roberts Noble Foundation Ardmore, OK� Juli Wade Departments of Psychology and Zoology; Michigan State University East Lansing, MI
Program in Neuroscience
Funding/Grants� John Cunningham* Department of Hematology/Oncology St. Jude Children's Research Hospital Memphis, TN� Adrian Whitty* Drug Discovery Biogen Idec Cambridge, MA� Allen Wilcox Epidemiology Branch National Institute of Environmental Health Sciences Durham, NC
Employer/Situation� Ashutosh Chilkoti Department of Biomedical Engineering Duke University Durham, NC� David Eisenberg* HHMI, Departments of Chemistry & University of California at Los Angeles (UCLA) Los Angeles, CA
Biochemistry and Biological Chemistry� Matthew Mescher Center for Immunology (and Dept. University of Minnesota Minneapolis, MN
of Laboratory Medicine & Pathology)
Networking� Karlyne Reilly* Mouse Cancer Genetics Program, National Cancer Institute Frederick, MD
Center for Cancer Research� John Tamkun Department of Molecular, Cell and University of California, Santa Cruz Santa Cruz, CA
Developmental Biology� Watt Webb* School of Applied and Engineering Physics Cornell University Ithaca, NY
PRINCIPAL INVESTIGATOR DEPARTMENT INSTITUTION CITY, STATE
Note: Individuals listed in the above table are representative of those with top scores in each category and are listed by alphabetical order. An asterisk indicates individuals interviewed for this article.
Success Factors for Postdocs
advertising supplement
Computing and Computational SciencesThe Oak Ridge National Laboratory (ORNL) in Tennessee is a leading center for basic and applied research inhigh-performance computing, computational sciences, systems engineering, intelligent systems, mathematics,and computer sciences. Our mission includes work on national priorities in advanced computing systems,work for U.S. government and industry customers to enable efficient and cost-competitive design, and workwith universities to enhance science education and scientific awareness. Our researchers are finding newways to solve problems beyond the reach of most computers and are putting powerful software tools into thehands of government and academic researchers and industrial scientists throughout the country.
DOE Leadership-Class ComputingFacility for Science at ORNLEnergy Secretary Spencer Abraham announced onMay 12 that Oak Ridge National Laboratory will builda leadership-class computing facility for science overthe next five years at a total estimated cost between$150-$200 million. When finished, this computer willhave a sustained capacity of 50 trillion calculationsper second — or 50 teraflops — and more than 250trillion teraflops per second at its peak.
OpportunitiesMany new scientific and technical staff are needed now in specific initiatives or strategic research areas inthe Computing and Computational Sciences Directorate. Opportunities also exist for joint tenure-basedpositions with our university partners (see http://www.ornl.gov/ornlhome/university_partners.shtml). Weanticipate openings in the following research and applications areas:
To apply for specific current job openingsTo apply for specific current job openings, please visit: http://computing.ornl.gov/Employment
For additional information about these opportunities, please send an email, referencing a specific positionof interest in your subject line, to: [email protected]
ORNL, a multiprogram research facility managed by UT-Battelle, LLC, for the U.S. Department of Energy, isan equal opportunity employer committed to building and maintaining a diverse work force.
• Ultrascale Computing and Simulation• Visualization Research• Architecture/Software Research• Computer Science Research• Computational Biology• Computational Mathematics• Computational Materials• Computational Fusion (ITER)• Computational Chemistry• Computational Nanosciences• Climate Research and Modeling
• Systems Engineering• Complex Systems (Optical & Quantum Computing,
Laser Arrays, Optical Radars, and High-Performance Networks)
• Networking Research• Geospatial/Remote Sensing Science• Energy Infrastructure Modeling• Communications Infrastructure Modeling• Cyber Security and Information Infrastructure
Research
•
•
•
•
Oak Ridge National LaboratoryOak Ridge National Laboratory
1808 continued >>
necessity of doing one’s homework – that is, learning as much as pos-sible about the PI and the institution – before accepting any fellowship.
The Meaning of MentoringIf postdocs had to choose a single characteristic of a principal investi-gator that will ensure the success of a fellowship, the survey says thatthey would almost unanimously select mentoring. “Mentoring is key toa successful postdoc experience,” one respondent wrote. “Guidance/mentoring from a PI regarding career options and planning for a careerafter my postdoc should be required. When postdocs enter a lab, theyshould design a plan for what they hope to accomplish during theirpostdoc. Periodically, this plan should be evaluated by the postdoc andmentor to make sure progress is being made.”
Principal investigators mentioned as particularly effective mentorsby survey participants agree. “Mentoring is probably the most impor-tant factor in ensuring a successful postdoc experience,” says C. RichardLyttle, vice president of discovery in the Women’s Health ResearchInstitute and co-chair of the women’s health and bone therapeutic areaat pharmaceutical company Wyeth. “Doing a postdoc means movingfrom being a student to becoming an independent investigator.Mentors are there to help fellows grow up and go out to compete.”
While highly regarded mentors have a variety of styles, they agreeon the need for communication. “I try to talk with my fellows on anindividual basis twice a week in the lab,” says Joseph Bonventre, adirector of the Harvard-MIT Division of Health Sciences andTechnology (HST), and director of the renal division at Brigham andWomen’s Hospital in Boston. Lyttle recalls that he had a regularlyscheduled weekly meeting with his most recent postdoctoral fellow.“But he knew that he could see me at any time,” he adds. “Most of mypeople are able to find their way,” says Watt Webb, professor of physicsat Cornell University. “But when I see that they’re not, I step in.”
Effective mentoring involves two major strands. “A lot of mentoringis done by example. The PI sets the tone for the personal interactionsin the laboratory,” Bonventre explains. “But it’s also important to mon-itor what postdocs are doing and to avoid overlaps between the work
of different postdocs as much as possible.” Bonventre also encourageshis postdocs to learn how to write papers and grant applications andto develop the management skills necessary to run their own laborato-ries. Webb, meanwhile, aims to help his postdocs to work comfortablyin an interdisciplinary environment. “Mentoring in my lab is done large-ly by collaboration across disciplines,” he says.
Direction and VisionThe second most important characteristic of PIs – providing a sense ofdirection and vision for postdoctoral research – is a somewhat ambiva-lent concept. “It is essential that postdocs work in a group in which theyhave a defined project that will lead to significant publications,”explains Campbell of the University of Iowa. “But the contradiction isthat real research is not well defined. You need to give each postdoc avision that encourages them to think of novel and creative experiments.”
Adrian Whitty, head of quantitative biochemistry at biopharmaceu-tical firm Biogen Idec, takes a similar view. “It is very important that thegroup has a clear vision of what it is trying to achieve and what kindof questions are or are not relevant to these broad scientific objectives,”he says. “However, this vision should not be so constraining that itdeprives the postdoc of any flexibility when selecting the specific ques-tions to be studied and the approaches to be used. Only in this waydoes the postdoc have an opportunity to gain firsthand experience atmaking such judgments, which to my mind is a key component of com-prehensive postdoctoral training.”
Effective PIs must walk a narrow path between too much and too lit-tle autonomy for their fellows. “Postdocs often have better ideas of whatto do,” says Eisenberg of UCLA. “I as a supervisor can warn them of prob-lems in the way they want to go.” Whitty adds “I feel strongly that a fair-ly high level of autonomy is key to maximizing the value of the postdoc-toral experience. Within broad bounds set by the mentor, the postdocshould be free to make strategic and tactical decisions concerning thedirection of his or her work.” However, he points out, that approachinvolves a tradeoff. “By allowing the postdoc more say in the direction ofthe project, even at the cost of making the occasional mistake or false
Demographics of Survey Participants
Positions Desired by Current Postdocs/Positions Obtained by Former Postdocs
Postdoc Status ofSurvey Participants
Number of PostdocPositions Held
Type of PostdocInstitution Rated
TENURE-TRACKACADEMIC POSITION
PHARMACEUTICAL/BIOTECHNOLOGY
NONTENURE-TRACKRESEARCH SCIENTIST
GOVERNMENT
NONPROFIT RESEARCH
SELF-EMPLOYED
OTHER
58%
4%
0% 10% 20% 30% 40% 50% 60% 70%
WAS A POSTDOCTORALFELLOW 18%
ONE 68%
IS CURRENTLY APOSTDOCTORALFELLOW 82%
ACADEMIC 70%
TWO 26%
THREE 6%
BIOTECH/PHARMA 3%HOSPITAL 7%
NONPROFIT RESEARCH 7%GOVERNMENT 13%
23%
18%31%
11%3%
2%5%
3%12%
1%
4%
Success Factors for Postdocs
advertising supplement
25%
FORMER POSTDOCSCURRENT POSTDOCS
start,” he says, “the work may advance more slowly.” Eisenberg points outa further key factor in any lab’s or scientist’s vision of research. “There hasto be flexibility about what the goal is,” he says. “It can change.”
Funding and GrantsSurvey participants also pinpoint the ready availability of funding andgrants for their research as a key success factor. Here again, successfulPIs agree. Most aim to fund their postdoctoral research fully, whileencouraging the fellows to search for ancillary grants.
“Our postdocs have no pressure obtaining research grants. I say thatwhatever experiments they want to do, we can support financially. Afterall, a postdoctoral fellowship is still an educational process,” says JohnCunningham, an associate member in hematology-oncology at St. JudeChildren’s Research Hospital in Memphis. “But I encourage my postdocsto apply for other grants. Learning how to do so is important for theircareers.” Campbell at The University of Iowa has a similar attitude. “Themajor funding in the laboratory is the PI’s responsibility,” he says. “I wantto keep the postdoc free of that pressure, but I expect all of my postdocsto pursue their own fellowship funding even though I have the fundingfor their research activities. This is an important part of their postdoc-toral training; writing individual grant applications is part of the learn-ing process for becoming a successful, independent professor.”
Principal investigators usually accept the need to prepare their post-doctoral fellows for careers, in academe, government, or industry, andthereby fulfill the demands of respondents to the survey. “You can haveall the good mentoring in the world,” says Wyeth’s Lyttle, “but how youare judged ultimately is based pretty much on your resume. It’s yourticket to get in there.” The company lists cutting edge science and theopportunity to publish in good journals as key criteria in determiningthe need for postdoctoral positions. And it aims to include its postdocsas the first authors on papers that it submits to journals.
Working up a research project into a publishable paper is a skill thatmost postdocs must learn. Here again the PI should take a leading rolein the instruction. “Success in research depends critically on communi-cation,” UCLA’s Eisenberg says. “Learning to write and speak is essential.We need to have a culture in which the communication is continuous.”
Using ConnectionsHelping a postdoc to take the first career step involves more thanencouraging publications. PIs routinely use their connections to helpplace their fellows. “You encourage people you know in the field to goto postdocs’ presentations,” Lyttle says. “And you need to find outwhere your postdocs are best suited to work, whether in the pharma-ceutical business or in academe.”
Equally important, and recognized by participants in our survey, isgiving postdocs the opportunity to network within the scientific com-munity, by making presentations, attending meetings, and gettingtogether informally with specialists in their fields. “Often, individualsare recruited for a job interview because of a personal contact – thepeople in charge of hiring have met the individual or have seen theirwork at a meeting, and have felt it fit the program’s goals,” says KarlyneReilly, a principal investigator at the National Cancer Institute.“Because there’s an element of luck to finding the right job, the more
A former science editor of Newsweek, Peter Gwynne ([email protected]) cov-
ers science and technology from his base on Cape Cod, Massachusetts, U.S.A.
1810
you can increase your luck by getting to know people in your field.”Reilly encourages her fellows to present a poster at at least one
national meeting a year and to attend as many local meetings as pos-sible. “There they can meet people with different ideas from the waywe think about our science within our lab,” she says. “They should alsoget practice defending their ideas, an important factor for their futurework. And when I’m meeting colleagues, I try to have postdocs work-ing on relevant research come with me.”
Webb at Cornell also encourages his fellows to network at meet-ings and through personal introductions. “It’s crucial that they shouldstart thinking about it more than a year before they start looking fora job,” he says. “Early on, it’s really networking to communicate in sci-ence; the job business comes later.”
Bonventre of Brigham and Women’s Hospital and HST wants toexpose his postdocs to the entire range of networking opportunities.“No matter what they are going to do,” he says, “it’s important to havenetworking across the academic-industry barrier. You’ll tend to focusmore on one direction, but try to expose fellows to the other side.”
Institutional ContributionsWhile institutions feature as relatively minor contributors to postdoc-toral success in the survey, authorities have recently started to increasetheir support for fellows. The National Cancer Institute provides dedi-cated funds to send fellows to meetings. “We also have local facultymeetings to which we’re encouraged to bring our postdocs,” Reilly says.“And when we have speakers visit, we set up lunches for them with ourpostdocs.” At St. Jude, adds Cunningham, “We have a five-year-oldAcademic Programs department that recruits postdocs and providessupport throughout their time here.” Biogen Idec also has a formalsetup for dealing with its fellows. “The director of our postdoctoral pro-gram meets individually with each postdoc on a quarterly basis, to dis-cuss whether the program is meeting their expectations,” Whitty says.
Other organizations are adapting their programs to the growingneeds of fellows. “We’re looking at our whole postdoc program,” saysWyeth’s Lyttle. “We have a postdoc day when the postdocs meet withsenior staff here and present their work. And we often try to set upexternal collaborations with academics. That lets the postdocs see whatgoes on in the academic side.” Universities increasingly recognize theneed to provide more institutional support for postdoctoral fellows.“They can make it easier for them to apply for grants, give special work-shops on applying for fellowships, and take away some of the admin-istrative load that comes with grants,” Iowa’s Campbell says.
The National Postdoctoral Association offers its own encouragement topostdocs and their mentors. “We’re developing toolkits that postdoctoralassociations and offices can use to bring about institutional changes,”Reed says. “We’re working through institutional and postdoctoral leader-ship to create opportunities for PIs to focus on issues of importance topostdocs to a greater extent than in the past. And, we’re particularly inter-ested in the bigger picture as seen by former postdocs. We’re trying tofind ways to connect the wisdom of former postdocs to present postdocs.”
Success Factors for Postdocs
advertising supplement
Otherscall it research.
We call it changing the medical textbooks.
www.gene.com
For over 28 years, Genentech has been at the forefront of the biotechnology industry, using human geneticinformation to discover, develop, commercialize and manufacture biotherapeutics that address significant unmetmedical needs.
With more than 500 scientists publishing at a rate of 200+ papers a year and more than 4,600 patents,Genentech provides a vibrant and intense environment for advanced scientific training. As a member of ourPostdoctoral Program, you will conduct basic and applied research in collaboration with world-class researchers as well as publish in scientific journals and present at scientific meetings. Genentech combines the best of theacademic and corporate worlds, allowing researchers not only to pursue important scientific questions but also to watch an idea move from benchside to bedside. Postdoctoral work at Genentech offers an unrivaled opportunity to put yourself at the forefront of biomedical science.
Postdoctoral OpportunitiesMammalian Cell Culture Development(Ph.D. in Molecular/Cellular Biology or related discipline) • Study of CHO cell biology utilizing gene chip and
molecular biology techniques to improve cell culture processes.Req. #1000004062
• Engineering of CHO cell lines to manipulate glycosylation profiles. Req. #1000004063
Protein Engineering(Ph.D. in Biochemistry or related discipline)• Investigate biochemical aspects of protein/protein
interactions and structure function relationships. Collaborative multidisciplinary projects in protease enzymology, growth factors/receptors, molecular recognition. Background in molecular biology, proteins, structure, phage display. Req. #1000003757
Pharmaceutical Development and Technology(Ph.D. in Chemical Engineering or related discipline) • Evaluate technologies for analyzing protein aggregation,
including light scattering, field flow fractionation and analytical ultracentrifugation. Req. #1000004075
• Focus on mathematical modeling and laboratory characterization of transport phenomena in biopharmaceutical processing (e.g. lyophilization, freezing and thawing of protein solution).Req. #1000004076
Analytical Chemistry Development(Ph.D. in Analytical Chemistry or related discipline) • Develop capillary electrophoresis (CE) based methods for
nucleic acid analysis. Req. #1000004060• Develop qualitative and quantitative mass spectrometric
methods for profiling glycosylation and other heterogeneity of natural and recombinant antibodies. Req. #1000004061
Molecular Oncology(Ph.D. in Molecular Oncology or related discipline or M.D.)• Study the mechanism of regulation of angiogenesis, with an
emphasis on tumor angiogenesis. Apply genomic and proteomic approaches to identify novel angiogenic regulatorsand utilize state-of-the-art tools to elucidate the in vivo and in vitro functions of these molecules. Req. #1000002928
Immunology(Ph.D. in Immunology or related discipline or M.D.)• Extensive research experience in immunology and
molecular biology with good publication record, to study T cell differentiation and development, cytokine function, and the roles of T cell subtypes in autoimmune diseases. Req. #1000001009
Molecular Biology(Ph.D. in Immunology or related discipline or M.D.)• Explore and define the function of recently discovered
cytokines at the molecular level. Make use of animal models and sophisticated in vitro techniques. Applicants should have a strong immunology background. Req. #1000001513
Consistently recognized as one of the top companies to work for in the United States, Genentech offers employees one of the most comprehensive benefits programs in the industry. For immediate consideration, visit www.gene.com/careers and reference theReq. #. Please use “Science Magazine” when a “source” is requested. Genentech is an equal opportunity employer.
RESEARCH POSITIONSPOSTDOCTORALandJUNIORRESEARCH-
TRACK POSITIONS are available for highly moti-vated career-oriented individuals to: (1) study thefunctions of estrogen receptor coregulators and up-stream growth-factor signaling components as relatedto hormone-resistant, non-genomic, and chromatinremodeling functions; (2) characterize transgenicmice expressing MTA1 family members and PELP1/MNAR mutants; (3) Characterize knockout mousemodels of MTA1 and PELP.
(For recent publications from the laboratory, see:NCB 3:30, 2001; Nature 418:654, 2002; NCB4:681, 2002; Cell 113:142, 2003. J. Biol. Chem. 276:38272, 2001, 2002; EMBO J. 21:5437, 2002; J. CellBiol. 161:583, 2003.)
Candidates should have a Ph.D. in molecular biol-ogy, cell biology, or genetics. Candidates with priorpublications and direct experience will be preferred.Salary is highly competitive and commensurate withexperience.
For immediate consideration, send curriculum vitaeto: Rakesh Kumar, Professor and John G. andMarie Stella Kenedy Memorial Foundation Chair,The University of Texas M. D. Anderson CancerCenter–108, 1515 Holcombe Boulevard, Hous-ton, TX 77030. E-mail: [email protected].
The University of Texas M. D. Anderson Cancer Center isan Equal Opportunity Employer and does not discriminate onthe basis of race, color, national origin, gender, sexual orienta-tion, age, religion, disability, or veteran status, except wheresuch distinction is required by law. All positions at M. D.Anderson are considered security sensitive; drug screening andthorough background checks will be conducted. The University ofTexas M. D. Anderson Cancer Center values diversity in itsbroadest sense. Diversity works at M. D. Anderson. Smoke-freeenvironment.
POSTDOCTORAL SCIENTISTAnalytical Biochemistry
The Biosystems Research Department at SandiaNational Laboratories in Livermore, California, seeksPostdoctoral Scientists to perform research in bioana-lytical chemistry. The individual will work in a multi-disciplinary team involving analytical chemists, bio-chemists, and engineers to develop portable devicesand assays for clinical diagnostics. Responsibilities willinclude developing novel protein modification, label-ing, and immobilization chemistries; protein purifica-tion and characterization; and developing immunoas-says for clinical analytes. Research may also involveworking with mammalian cells and bacteria.
Qualifications: Ph.D. in chemistry, biochemistry, ora related field is required. Experience with one ormore of the following is necessary: bioconjugatechemistry, immunoassays, enzyme assays, protein sep-aration, protein purification, and cell culture tech-niques. Experience with spectroscopy, optical micros-copy and/or mass spectrometry is desired.
Interested candidates should apply electronically atwebsite: http://www.sandia.gov. The job requisi-tion number is 050879.
Sandia is an Equal Opportunity Employer.
POSTDOCTORAL RESEARCH ASSOCIATENational Jewish Medical and Research CenterPosition immediately available in the laboratory of
Dr. Brian J. Day to help discover and develop novelcatalytic antioxidants and apply these novel com-pounds in acute and chronic lung injury models.Seeking Ph.D. in molecular biology/pharmacologyor toxicology with experience in cell culture, molec-ular biology, biochemistry, and analytical chemistry(high-performance liquid chromatography, gas chro-matography/mass spectroscopy). Excellent benefitsand competitive salary. Please send curriculum vitaeand three references to:
Dr. Brian J. DayNational Jewish Medical and Research Center
1400 Jackson Street, K706Denver, CO 80206
E-mail: [email protected] Action/Equal Employment Opportunity
Employer.
THE CENTER FORGENOMIC SCIENCES
www.centerforgenomicsciences.orgPOSTDOCTORAL POSITION to study the
molecular biology of medically important mucosalbiofilms, and to explore the clinical relevance of hor-izontal gene transfer among bacterial strains duringchronic biofilm infections. The Center for GenomicSciences is seeking an energetic person to work inmultidisciplinary team environment who is interestedin bacterial evolution and genetics. Applicants shouldhave extensive experience in all aspects of bacterialstrain construction with preference given to thosewith experience in H. influenzae or S. pneumoniae. Po-sition is NIH-grant supported. Send letter of interest,curriculum vitae, and copies of manuscripts to e-mail:[email protected].
POSTDOCTORAL POSITIONS in molecular/cell biology of bacterial pathogenesis. Postdoctoralpositions are available in the laboratory of Dr. Ran-dall Holmes at the University of Colorado HealthSciences Center. Potential projects include: investi-gating structure, function, and trafficking of choleratoxin from V. cholerae, and the related heat-labile en-terotoxins from E. coli; characterizing the closely re-lated metalloregulatory proteins DtxR and IdeR fromC. diphtheriae and M. tuberculosis and their roles in globalregulation of iron-dependent gene expression and vir-ulence; and developing novel structure-based meth-ods for treatment and prevention of diseases caused bythese bacterial pathogens. Research facilities and pro-fessional environment are excellent, and we will occu-py entirely new research laboratories later this year.Recreational facilities of the beautiful Rocky Moun-tains are easily accessible. Salary is commensurate withtraining and experience. Submit curriculum vitae,bibliography, and names of three professional refer-ences to: Dr. Randall Holmes at the Departmentof Microbiology, Campus Box B-175, Universityof Colorado Health Sciences Center, 4200 EastNinth Avenue, Denver, CO 80262. The University ofColorado Health Sciences Center is committed to Equal Em-ployment Opportunity and Affirmative Action. Citizens andpermanent residents of the United States may be considered forpositions on an NIH-funded training grant, and individualsfrom underrepresented groups are encouraged to apply.
POSTDOCTORAL POSITIONDepartment of Health and Human Services
National Institutes of HealthNational Cancer Institute
The Biomolecular Structure Section (BSS) of theMacromolecular Crystallography Laboratory, Na-tional Cancer Institute at Frederick is inviting appli-cations for a Postdoctoral position. Training and ex-perience in macromolecular crystallography are essen-tial. Knowledge and skills in protein engineering, ex-pression, purification, and characterization aredesirable. Information about the research activities ofthe BSS can be found at website: http://mcl1.ncifcrf.gov/ji.html. Excellent work environ-ment, state-of-the-art facilities, and regular access tothe Advanced Photon Source at Argonne NationalLaboratory will be provided. Please send curriculumvitae, research summary, and contact information ofthree references to: Dr. Xinhua Ji at e-mail:[email protected]. We offer competitive salary andcomprehensive health insurance. DHHS and NIH/NCI are Equal Opportunity Employers.
A POSTDOCTORAL POSITION is available inthe laboratory of Anna Aldovini at Children’s Hos-pital and Harvard Medical School to support a re-search program on HIV biology and AIDS vaccinedevelopment. Highly motivated applicants must havea Ph.D. degree, strong experience in molecular biol-ogy and/or immunology techniques, and good com-munication skills. Send curriculum vitae with namesand addresses of three references to: Anna Aldovini,Children’s Hospital, Enders 861, 300 LongwoodAvenue, Boston, MA 02115 or to e-mail:[email protected].
POSTDOCTORAL SCIENTISTMicrofluidics/Microseparations
The Biosystems Research Department at SandiaNational Laboratories in Livermore, California, seeksPostdoctoral Scientists to perform research in applica-tion of microfluidics/microseparations to chemicaland biochemical analysis. The individual will work ona multidisciplinary project involving analytical chem-ists, polymer chemists, biochemists, and engineers todevelop miniaturized devices and techniques for clin-ical diagnostics and proteomics research. The researchwill involve work with laboratory-on-a-chip tech-niques, spectroscopy, microscopy, and mass spec-trometry.
Qualifications: Ph.D. in analytical chemistry, ana-lytical biochemistry, or engineering (chemical, me-chanical, or biological) is required. As is extensiveexperience in one or more of the following areas:microfluidic devices or components, theoretical fluiddynamics, microarrays, electrophoresis, chromatogra-phy, immunoassays, and enzyme assays. Knowledgeof one or more detection technologies such as fluo-rescence, electrochemical, and mass spectrometry isalso desired.
Interested candidates should apply electronically atwebsite: http://www.sandia.gov. The job requisi-tion number is 050878.
Sandia is an Equal Opportunity Employer.
POSTDOCTORAL POSITION is available tostudy transcriptional control of mammalian oogenesis(Rajkovic et al., Science 305 (5687):1157�1159,2004). We have identified several oocyte-specifictranscription factors essential in mammalian oogene-sis and continue to use genomic approaches to iden-tify novel genes involved in oogenesis. We utilizemouse knockouts to study the function of these novelgenes in mammalian oogenesis.
Experience in molecular biology, cellular biology,protein biochemistry, microarray, and/or animalmodels are desirable.
The position is available as of September 1, 2004.Please forward your curriculum vitae and names, ad-dresses, and telephone numbers of at least three ref-erences to e-mail: [email protected].
Aleksandar RajkovicBaylor College of Medicine
Department of Obstetrics and GynecologyHouston, TX 77030
E-mail: [email protected]: 713-798-8410
Fax: 713-798-5833Equal Employment Opportunity Commission/Equal Ac-
cess/Affirmative Action Employer.
Three POSTDOCTORAL POSITIONS areavailable starting January 2005 in the Department ofMedical Microbiology and Immunology, School ofMedicine, University of California at Davis (UCD)with Dr. Shirley Luckhart to study cell signaling ofinnate immunity during malaria parasite infection inAnopheles mosquitoes. Candidates with peer-reviewedpublications and Ph.D. background in molecular cellbiology, protein analysis, and/or immunology of in-fectious diseases preferred. Salary commensurate withexperience. Send curriculum vitae and names andcontact information for three references to: Dr.Shirley Luckhart, 3146 Tupper Hall, Universityof California Davis, One Shields Avenue, Davis,CA 95616. UCD School of Medicine is an Equal Employ-ment Opportunity/Affirmative Action Employer.
POSTDOCTORAL/POSTDOCTORALSCHOLAR
A position is available to work on aspects of theMdm2-PTEN-p53 oncogene-tumor suppressor net-work (Trends in Biological Sciences 27:(9)462�466,2002). Effective communication skills are an absoluterequirement. Salary depending on experience. Ph.D.and/or M.D. required. Interested candidates shouldsend a letter stating interests, curriculum vitae, andthree references to: Dr. Lindsey Mayo (e-mail:[email protected]). Applicants must be U.S. residents orhave current visa status.
POSITIONS OPEN POSITIONS OPEN POSITIONS OPEN
17 SEPTEMBER 2004 VOL 305 SCIENCE Science Careers www.sciencecareers.org1812
At Roche Palo Alto, we are dedicated to discovering and developing medicines that improve the lives of people affected
by serious illness. Our formula for success: highly talented, results-driven scientists and a world-class environment
equipped with cutting-edge technologies. Through our Postdoctoral Fellowship Program, we bring together
outstanding researchers to formulate the medicines of the future. We are currently seeking Postdoctoral Fellows for
opportunities in DMPK, Virology, Genetics/Genomics, and Modeling/Simulation.
Located in the San Francisco Bay Area, our park-like campus offers a wide array of professional amenities. We are
pleased to provide competitive compensation and benefits, including relocation assistance and a generous vacation
and holiday schedule.
http://paloalto.roche.com
As an equal opportunity employer, we are committed to workforce diversity.
Postdoctoral FellowshipsA meeting of great minds
PO
ST
DO
CTO
RA
L O
PP
OR
TU
NIT
IES
NIH POSTDOCTORAL POSITIONION CHANNEL BIOPHYSICS
The National Institute of Neurological Disordersand Stroke (NINDS), a major component of the NIH,and the Department of Health and Human Services, isrecruiting to fill a Postdoctoral position to study themechanisms of gating and selectivity of chloride-conducting ion channels in the chloride channel (ClC)family. Our laboratory (website: http://intra.ninds.nih.gov/Lab.asp?Org_ID�477) uses several ap-proaches, including fluorescence spectroscopy andelectrophysiology, to understand these phenomena,taking advantage of recently solved chloride channelcrystal structures to focus our attention on critical pro-tein domains. Projects include using site-directed flu-orescence labelling to monitor conformational chang-es in prokaryotic ClC proteins, as well as electrophys-iology of prokaryotic and eukaryotic chloride channelsin cells and lipid-bilayer membranes. The laboratory ispart of a lively community of ion channel researchers atthe NIH. Candidates must have a Ph.D. and/or M.D.and should have a strong background in electrophysi-ology or membrane protein biophysics. Salary is com-mensurate with experience. Interested candidatesshould send curriculum vitae and a statement of re-search interests to:
Joseph A. Mindell, M.D./Ph.D.Membrane Transport Biophysics Unit
NIH/National Institute of NeurologicalDisorders and Stroke
36 Convent Drive, Building 35Room 3B1014, MSC 3701Bethesda, MD 20892-3701Telephone: 301-402-3473
E-mail: [email protected], NIH, and NINDS are Equal Opportunity Employers.
RESEARCH IN GERMANYThe Alexander von Humboldt Foundation’s Re-
search Fellowship Program supports scientists of allnationalities and fields as they conduct research inGermany for a period of six to 12 months. Applicantsmust be under 40 and have a Ph.D. Scientific excel-lence and the feasibility of the proposal are the prima-ry selection criteria.
U.S. citizens and residents may also apply for: (1) 3 x 3(Summer) Research Fellowship (three months peryear in three consecutive years and visits may be anytime of year); (2) Two-year Research Fellowship (24consecutive months).
Applications are accepted at any time. For informa-tion on these and other programs, see website:http://www.humboldt-foundation.de or contactthe Foundation’s U.S. Liaison Office at e-mail:[email protected].
ADVANCED POSTDOCTORAL FELLOW-SHIP. Laboratory of Stephen B. Liggett is seeking afellow with potential for subsequent faculty positionat the University of Cincinnati College of Medicine.Research expertise in G protein coupled receptor bi-ology, pharmacogenetics, or transgenic mice prefera-ble. Send resume to: Stephen B. Liggett, Universityof Cincinnati College of Medicine, 231 AlbertSabin Way, Room G167, P.O. Box 670564, Cin-cinnati, OH 45267-0564; telephone: 513-558-0484;fax:513-558-0835;e-mail:[email protected]. The University of Cincinnati is an Equal Opportu-nity Employer and encourages the application of women andminorities.
POSTDOCTORAL POSITIONCOMPUTATIONAL BIOLOGY
Johns Hopkins UniversityImmediate position available in the Bader laborato-
ry for a Ph.D. trained in computational biology,bioinformatics, or related theoretical/computationalfields. Research areas include biological networks,protein-DNA structural biology, and genetic screens.See website: http://www.jhubiomed.org and Sci-ence 302:1727, 2003. Applications should be sent toe-mail: [email protected] and include curriculumvitae, research interests, and the names of three refer-ences with permission to contact them directly.
THE CENTER FORGENOMIC SCIENCES
www.centerforgenomicsciences.orgPOSTDOCTORAL POSITION to study the
molecular biology of scarless wound healing. TheCenter for Genomic Sciences is seeking a highly mo-tivated individual to join a dynamic multidisciplinaryteam committed to identifying and translating funda-mental biological findings in wound repair into im-proved patient care. The successful applicant willwork in a highly cooperative basic research environ-ment in superbly equipped laboratories set within arenowned clinical care facility. Applicants should beproficient in differential gene expression, molecularcloning, and related technologies. Position is NIHfunded. Send letter of interest, curriculum vitae, andcopies of manuscripts to e-mail: [email protected].
RESEARCH FELLOWSHIPSArnold Arboretum
The Arnold Arboretum of Harvard University in-vites applications for one- and two-year POSTDOC-TORAL FELLOWSHIPS in the areas of plant evo-lutionary biology, biogeography, plant systematics,plant development, and plant physiology. Priority willbe given to candidates whose research makes use ofthe extensive living (Putnam Fellowships), preserved(Mercer Fellowships), and library botanical collec-tions of the Arboretum and the Harvard UniversityHerbaria. Candidates must be associated with a re-search scientist or faculty member based at the ArnoldArboretum, Harvard University Herbaria, or Depart-ment of Organismic and Evolutionary Biology. Appli-cations should consist of curriculum vitae, researchproposal, required support, statement from a Harvardsponsor, and three letters of recommendation. Re-view of applications will begin on December 1, 2004.Applications should be sent to: Dr. Robert E. Cook,Director, Arnold Arboretum, 125 Arborway, Ja-maica Plain, MA 02130. The Arnold Arboretum ofHarvard University is an Equal Opportunity/Affirmative Ac-tion Employer.
POSTDOCTORAL POSITIONSBaylor College of Medicine
Department of Pediatrics andCenter for Cell and Gene Therapy
NIH-funded Postdoctoral positions available im-mediately to investigate novel oncolytic agents andimmunotherapy for treatment of solid tumors. Specif-ic focus is on incorporating therapeutic genes intooncolytic herpes simplex virus to enhance its antitu-mor effect and to boost antitumor immune responses.Applicants with a strong background in molecularbiology and immunology is highly desirable. The can-didate must have a Ph.D. and/or M.D. degree, andbe able to work independently and communicate ef-fectively. If interested, please contact: Dr XiaoliuZhang at telephone: 713-798-1256 or send resumeand contact information for three references throughe-mail: [email protected].
Baylor College of Medicine is an Equal Opportunity/Affirmative Action/Equal Access Employer.
POSTDOCTORAL POSITIONDepartment of Pharmacology, Toxicology,
and TherapeuticsUniversity of Kansas Medical Center
Tumor Molecular Biologist, Ph.D. To study therole of cell cycle, Aurora-A kinases, and centrosomalprotein interactions in animal models of estrogen on-cogenesis. Strong background in molecular and tu-mor biology, cell culture, use of bacterial artificialchromosome/cosmid libraries, and co-immuno-precipitation required. Applicants must be proficientin the use of the English language. Please apply onlineonly at website: http://jobs.kumc.edu. Search forposition # J0201299.
The University of Kansas Medical Center is proud to be anEqual Opportunity/Affirmative Action Employer.
Two NIH-funded POSTDOCTORAL RE-SEARCH POSITIONS are available immediately tostudy calcium-dependent signaling in fungal patho-gens during host infection. The successful candidateswill join a highly motivated and committed researchteam and use a multidisciplinary approach to resolvethe role of calcium channels in promoting fungalpathogenesis. One individual will use patch-clamptechniques and molecular biology to performstructure-function studies of a newly identified calci-um channel found in the pathogen. This individualshould have extensive experience with electrophysiol-ogy and molecular biology. A second individual willexamine the interactions between the channel andsignaling cascades by identifying protein interactors ofthe channel and using a murine model of fungal in-fection. A background in signal transduction, yeastgenetics, and ion transport would be an asset. Send ore-mail curriculum vitae, research interests, and namesof three references to: Dr. Angela Gelli, Genomeand Biomedical Sciences Facility, Department ofMedical Pharmacology and Toxicology, Universi-ty of California, Davis, 451 East Health SciencesDrive, Room 3502, Davis, CA 95616. E-mail:[email protected].
POSTDOCTORAL POSITION in ecology andevolution of a bird-borne alphavirus. An NIH-fundedPostdoctoral position is available immediately tostudy the population dynamics of Buggy Creek virus,an alphavirus associated with cliff swallows and theircimicid ectoparasites (see: Proc. R. Soc. Lond. B 268:1833, 2001). The position includes both field- andlaboratory-based work and requires travel to and fromperformance sites in Nebraska, Colorado, Oklahoma,and Munich, Germany. Applicants should have aPh.D. and background in virology, epidemiology, orphylogenetics. To apply, send curriculum vitae andnames and addresses of three references to: CharlesR. Brown, Department of Biological Sciences,University of Tulsa, 600 S. College Avenue, Tul-sa, OK 74104; e-mail: [email protected] University of Tulsa is an Equal Opportunity/AffirmativeAction Employer.
POSTDOCTORAL FELLOW POSITIONS areavailable in cell biology, The Hospital for Sick Chil-dren Research Institute, to join our interdisciplinaryprogram studying quality control of membrane pro-tein, structure-function relationship, proteomics, andtrafficking determinants of cystic fibrosis transmem-brane conductance regulator (CFTR), as well as therole of CFTR in inflammation (see: Nature Struct. Biol.5:180�183, 1998; J. Cell Biol. 164:923, 2004, and153:957, 2001). Candidates must hold a Ph.D. andhave a strong background in molecular-, cell-biology,and protein biochemistry. Experience in mass spec-troscopy, transgenic mice, or electrophysiology is anasset. Submit curriculum vitae, three references, anddescription of research interest to: Gergely L. Lukacsat e-mail: [email protected].
A POSTDOCTORAL POSITION is available inthe laboratory of Dr. David Dooley, Department ofChemistry and Biochemistry at Montana State Uni-versity, Bozeman. This position is open immediatelyfor an individual with a Ph.D. in chemistry, biochem-istry, or related field. The individual will conduct re-search on the molecular biology and protein engi-neering of metalloenzymes and will utilize spectro-scopic and kinetic methods to characterize these en-zymes. For more information on how to apply, pleasesee the following website: http://www.montana.edu/cgi-bin/msuinfo/fpview?ctype�p&csn�247-3. ADA/Affirmative Action/Equal Opportunity Em-ployer/Veteran’s Preference.
POSTDOCTORAL POSITION for one and ahalf years to develop a novel method to identify syn-thetic genetic relations in yeast and animal cells usingmicroarrays. To begin at once. U.S. citizens and perma-nent residents. Contact e-mail: [email protected]. (Pathology, Case Western Reserve Universi-ty, Cleveland, Ohio).
POSITIONS OPEN POSITIONS OPEN POSITIONS OPEN
17 SEPTEMBER 2004 VOL 305 SCIENCE Science Careers www.sciencecareers.org1814
The Argonne National Laboratory Named Postdoctoral Fellowship Program
The Director’s Office initiated these special postdoctoral fellowships at Argonne National Laboratory, to be awarded internationallyon an annual basis to outstanding doctoral scientists and engineers who are at early points in promising careers. The fellowshipsare named after scientific and technical luminaries who have been associated with the Laboratory and its predecessors, and theUniversity of Chicago, since the 1940’s.
Candidates for these fellowships must display superb ability in scientific or engineering research, and must show definite promiseof becoming outstanding leaders in the research they pursue; the Laboratory intends to award four such fellowships this comingyear. Fellowships are awarded for a two-year term, with a possible renewal for a third year, and carry a stipend of $70,000 perannum with an additional allocation of up to $20,000 per annum for research support and travel.
Applying for an Argonne Named Postdoctoral Fellowship:
Your application requires the following documents which must be sent via e-mail to: [email protected] by November 12, 2004.• Letter of Nomination (Recommendation from individual who supports your candidacy for the fellowship.)• Curriculum Vitae (Include the names of the Nominator and two additional references.)• Two letters of reference (It is the candidate’s responsibility to arrange that the two reference letters be sent to the Laboratory
via e-mail prior to the November 12, 2004 deadline.) • Bibliography of publications• Bibliography of preprints• Description of research interests to be pursued at the Laboratory (We encourage applicants to contact Argonne staff in their
areas of interest in order to explore possible areas of research.)
All correspondence should be addressed to ANL Named Postdoctoral Fellowship Program. One application is sufficient to beconsidered for all named fellowships.
For additional details, visit the Argonne web site at http://www.anl.gov.
Argonne is an equal opportunity employer.
individual
find morewww.jnj.com/careers© Johnson & Johnson Services, Inc. 2004. Johnson & Johnson companies are equal opportunity employers.
SMALL-COMPANY ENVIRONMENT/BIG-COMPANY IMPACT is a service mark of Johnson & Johnson.Johnson & Johnson Services, Inc. is a member of the Johnson & Johnson Family of Companies.
At the Johnson & Johnson companies, we believe everyone has something to contribute, and we empower them to have an impact.
You’d like to find an organization that values your own experience, thinking style, and perspective. Youwant to work for a trusted company, within a culture that fosters teamwork. At the same time, you needan organization that encourages community and professional involvement.
At the Johnson & Johnson companies, we celebrate and promote small-company environments thatsupport the needs of individuals, families, and communities—with deeply rooted values that enhanceleadership opportunity for every qualified person. Through our global organization of over 200 companies,selling products in more than 175 countries, we enable each employee to take part in shaping globalhealth care. Our decentralized, adaptive organization reflects the diversity of a dynamic, global environment.
Discover how your individual talents can drive success within the Johnson & Johnson Family of Companies.
THE SUCCESS OF OUR COMPANIES
STARTS WITH THE
PO
ST
DO
CTO
RA
L O
PP
OR
TU
NIT
IES
EYE AND VISION RESEARCHAT HARVARD
THE POSTDOCTORAL PROGRAM “Molecular Bases of Eye Disease,” funded by the National Eye Institute, isdesigned to provide expertise in the most current molecular research techniques within the context of ophthalmic dis-eases. Thirty faculty mentors, all with appointments or affi liations with the Department of Ophthalmology at Harvard Medical School, are drawn from laboratories of the Massachusetts Eye and Ear Infi rmary, the Schepens Eye Research Institute, the Brigham and Women’s Hospital, the Massachusetts General Hospital, the Longwood Campus Basic ScienceDepartments, and the Department of Molecular and Cell Biology on the Cambridge campus.
Participants are expected to spend three-to-four years in training. Training involves (i) participation in full-time research to obtain a mastery of molecular techniques in biochemistry, cell biology, genetics, immunology, or neurobiology as applied to ophthalmology and vision; (ii) exposure to ophthalmic problems through a series of didactic courses, clinical grand rounds, seminars, journal clubs, and meetings; and (iii) writing grant proposals to obtain individual support for years two through four.
Positions are available for individuals immediately after the awarding of their terminal degree, and for those who have completed their postdoctoral clinical training. Candidates must have a Ph.D. or M.D. degree, and be citizens or perma-nent residents of the United States.
Applicants for this program can obtain information on the mentors and their research at the website: http://www.eri.harvard.edu/training/index.html. More detailed information on the application process and the program is available through Jennifer Schleicher, Schepens Eye Research Institute, 20 Staniford Street, Boston, MA 02114; phone: 617-912-7401; fax: 617-912-0117; email: [email protected].
The Schepens Eye Research Institute is an Equal Employment Opportunity Employer M/F/D/V.
Millennnium Pharmaceuticals Inc. is launching a Postdoctoral FellowshipProgram in the rapidly advancing area of Protein Homeostasis. Following on the success of the first-in-class proteasome inhibitor, bortezomib (VELCADE®), for the treatment of cancer, the initiation of this program presents a uniqueopportunity to join one of the industry’s leading multidisciplinary researchgroups in the field of protein homeostasis. We’re looking for highly talented and motivated PhDs in all research areas spanning chemistry, biochemistry,molecular, cellular and in vivo biology, algorithms and mathematics to participatein this exciting program. Fellows will integrate closely with the Discovery organization and have a real opportunity to learn the science of drug-discovery.They will be encouraged to present their findings at major scientific meetingsand will be expected to publish in leading peer-reviewed journals. We are lookingfor candidates to work in the following broad areas:
• Analysis and modeling of complex networks related to protein homeostasis• Biochemistry of the 26S proteasome: expression, localization, associated
proteins, regulation• Biochemistry and regulation of the unfolded protein response• Biochemistry and regulation of ubiquitin and ubiquitin-like protein
modification systems• Molecular genetic studies (in vitro and in vivo) of the cellular response
to VELCADE®
Preferred candidates will have recently received their PhD or have completed 2 to 3 years of postdoctoral studies. Experience in the area of protein homeostasis is an advantage, although candidates from other scientific backgrounds are encouraged to apply. Appointments will be for one year initiallywith renewal for a second and possibly a third year.
We are an equal opportunity employer committed to discovering the individual in everyone.
Breakthrough science. Breakthrough medicine.
Postdoctoral Program — Protein Homeostasis
Apply online at www.millennium.com
PO
ST
DO
CTO
RA
L OP
PO
RT
UN
ITIE
S
POSTDOCTORALPOSITIONS
To apply online and for information, see www.postdocs.stonybrook.edu or mail résumés to:Murray Lamond, Office of the President, Stony Brook University, Stony Brook, NY 11794-0701.
The Research Foundation of Stony Brook University/SUNY anticipates the following postdoctoral positions being available between October 2004 and May 2005.
• APPLIED MATH AND STATISTICSStudy protein-ligand binding.James Glimm, #WC-R-1614-04-09-S
• BIOCHEMISTRY AND CELL BIOLOGYBiochemical mechanism of Wnt signaling.Jen-Chih Hsieh, #WC-R-1616-04-09-SBiosynthesis, folding, degradation of glyco proteinsin yeast. William J. Lennarz, #WC-R-1603-04-09-SCrystallographic studies of ubiquitin-dependent proteindegration. Herman Schindelin, #WC-R-1618-04-09-SExpression, purification, and biophysical characterization of membrane proteins.Smita Mohanty, #WC-R-1625-04-09-SGlycosylation and cell wall biogenesis in yeast andpathogenic fungi. Neta Dean, #WC-R-1620-04-09-SPlant cell and molecular biology plant-pathogen interactions. Vitaly Citovsky, #WC-R-1600-04-09-SRegulation of endocannabinoid (andandamide) expression. Dale Deutsch, #WC-R-1619-04-09-SRole of novel virulence factors; molecular mechanism of bacterial pathogenesis.Wali Karzai, #WC-R-1629-04-09-SStructure and function of caveolin-1 and caveolae.Deborah Brown, # WC-R-1637-04-09-S Yeast chromatin modifying enzymes.Rolf Sternglanz, #WC-R-1624-04-09-S
• BIOMEDICAL ENGINEERINGBiopolymeric hydrogels for deliveringcytokines/DNA to enhance wound repair.Weiliam Chen, #WC-R-1611-04-09-SCardiovascular biofluid mechanics, computational fluid dynamics, thromboembolism.Danny Bluestein, #WC-R-1634-04-09-SIdentification of molecular, protein, andhistological markers of bone adaptation.Stefan Judex, #WC-R-1613-04-09-S
• CHEMISTRYBioorganic approaches to enzyme inhibition, tuberculosis drug discovery.Peter Tonge, #WC-R-1617-04-09-SDNA, surfactant complexes, colloids, fibers, modified fullerenes, and membranes.Ben Chu, #WC-R-1628-04-09-SFlow-induced polymer crystallization, spinning pro-cesses, nanoparticles, biodegradable polymers, andnanocomposites. Ben Hsiao, #WC-R-1627-04-09-SMembrane structure: enzymatic probes of lipid domains. Nicole Sampson, #WC-R-1632-04-09-S Vibrational, NMR, and fluorescence spectroscopy offluorescent proteins. Peter Tonge, #WC-R-1622-04-09-S
• ECOLOGY AND EVOLUTIONCommunity/ecosystem ecology of biological invasions. Jessica Gurevitch, #WC-R-1607-04-09-SGenetics and Phylogeography of herbivorous insects and their host plants. Douglas Futuyma,#WC-R-1612-04-09-S
• MINERAL PHYSICSHigh pressure and synchrotron X-rays studies.Jiuhua Chen, #WC-R-1623-04-09-S
• NEUROBIOLOGY AND BEHAVIORElectrophysiological analysis of spinal cord functions in rodents. L. Mendell, #WC-R-1604-04-09-SStudy of the structure/function of glutamate receptors. L. Wollmuth, #WC-R-1606-04-09-SVertebrate development genetics: axis formation and early patterning in zebrafish.H. Sirotkin, #WC-R-1605-04-09-S
• NUCLEAR CHEMISTRYNuclear Chemistry/Physics expertise in nuclear reactions, relativistic energies.Roy Lacey, #WC-R-1602-04-09-S
• PHYSICS AND ASTRONOMYAccelerator-based experimental particle Physics. John Hobbs, #WC-R-1609-04-09-SExperimental nucleon decay and neutrino particlephysics. Clark McGrew, #WC-R-1610-04-09-SNuclear and computational astrophysics: neutron starts, supernovae, gamma-ray bursters. James Lattimer, #WC-R-1631-04-09-SX-Ray diffractive imaging of biological and materials science specimens.Chris Jacobsen, # WC-R-1608-04-09-S
• PSYCHIATRYStructure/function of non-image-forming visual system. Larry Morin, #HS-R-1630-04-09-S
• PSYCHOLOGYData management and analysis, manuscript preparation, supervision of undergraduate RA’s.Anne Moyer, #WC-R-1621-04-09-S
������
• MOLECULAR GENETICSG protein-coupled receptors/morphogenesis f-pathogenic yeast. James Konopka,#HS-R-1633-04-09-S
• PATHOLOGYInteractions of francisella tularensis withcells of innate immunity. Marie Furie, #WC-R-1615-04-09-S
• PHARMACOLOGICAL SCIENCESMolecular cellular pharmacology; moleculartoxicology; structural biology; cell biology; animal pharmacology. Jeffrey E. Pessin, #HS-R-1636-04-09-SNeuroimmue interactions in the physiological and pathological mammalia central nervous system. Styliani-Anna Tsirka, #HS-R-1635-04-09-SStudy of molecular mechanisms of carcino-genesis. Arthur Grollman, #WC-R-1601-04-09-S
Cancer Immunology Training Program
The Ohio State University Comprehensive CancerCenter invites applications from motivated youngscientists for postdoctoral positions in an NCI-sponsored Cancer Immunology Training Program.Applicants must have a PhD and/or MD and be a US citizen or green card holder. Women and minorities are encouraged to apply. The mentors and their expertise are as follows:Yang Liu (Professor and Program Director):T cell recognition in cancer and autoimmunity; Clark Anderson (Professor): Biology of Fcreceptor; Rolf Barth (Professor): Neutron capture therapy of brain cancer; John Byrd(Professor): Antibody therapy of cancer;Michael A. Caligiuri (Professor): NK Cellimmunobiology and cancer therapy; William Carson (Associate Professor): Clinical cancer immunology; Philip Johnson (Professor):Gene therapy for HIV and cancer; Clay Marsh (Professor): Signal transduction and apoptosis; Fredika Robertson (Professor): Infl ammation and carcinogenesis; Susheela Tridandapani(Assistant Professor): Fc Receptor and antibodytherapy; Christopher Walker (Professor): T cellresponse to hepatitis virus C; Caroline Whitacre(Professor): Immunobiology of autoimmunity;Pan Zheng (Associate Professor): Cancer evasion of host immunity.
Please send an application to: Dr. Yang Liu, c/o Lynde Shaw, Division of Cancer Immunology, Department of Pathology, Ohio StateUniversity Medical Center, 1645 Neil Avenue, 129 Hamilton Hall, Columbus, OH 43210 ore-mail to: [email protected]. Specifythe name of the mentor that you are interested in working with.
Department of Health and Human ServicesNational Institutes of HealthNational Institute of Environmental Health Sciences
Human health and human disease result from threeinteractive elements: environmental factors, individualsusceptibility and age. The mission of the National Instituteof Environmental Health Sciences (NIEHS) is to reducethe burden of human illness and dysfunction fromenvironmental causes by understanding each of theseelements and how they interrelate. The NIEHS achievesits mission through multidisciplinary biomedical researchprograms.
Several postdoctoral positions are available immediatelyat NIEHS/NIH/DHHS to study: 1) the role of estrogenreceptors in the lung; 2) the role of eicosanoids inpulmonary immune function; and 3) the biologicalsignificance of cytochrome P450-derived eicosanoidsin the cardiovascular system. These projects will utilizenewly developed knockout and transgenic mice inestablished models of disease including allergic and non-allergic lung inflammation, lung fibrosis, cardiacischemia/reperfusion injury, hypertension andatherosclerosis. Applicants should possess a Ph.D.degree in Molecular Biology, Cellular Biology,Biochemistry, Immunology, Pharmacology, or a relatedfield, and have no more than five years of relevantpostdoctoral experience. Salary will be commensuratewith experience according to NIH guidelines. For detailsregarding on-going projects in the laboratory and a listof recent publications, please visit:http://dir.niehs.nih.gov/dirlpp/groups/zeldin/members.htm
For prompt consideration, send or e-mail cover letter,curriculum vitae including list of publications in peer-reviewed journals, and the names/phone numbers ofthree people who could provide letters of reference to:
Postdoctoral Research Opportunities
Darryl C. Zeldin, M.D.National Institute of Environmental Health Sciences111 T.W. Alexander Drive, Bldg. 101, MD: D2-01Research Triangle Park, NC [email protected]
DHHS and NIH areEqual Opportunity Employers
PO
ST
DO
CTO
RA
L O
PP
OR
TU
NIT
IES
Postdoctoral Positionsat the
University of Alabama at BirminghamThe University of Alabama at Birmingham (UAB) is one of the premier research universities in the US with internationally recognized research programs in bone biology and disease, trauma and infl ammation research,cancer, diabetes, digestive and kidney diseases, basic mechanism in AIDS pathogenesis, lung disease and Free Radical Biology among others. UABis committed to the development of outstanding postdoctoral training programs. It is one of the fi rst universities in the US to establish an offi ceof postdoctoral education.
UAB is recruiting candidates for postdoctoral positions for a variety of research projects. UAB faculty are well funded (20th in 2003 NIH funds nationally), utilize multidisciplinary approaches, and provide excellent research training environments that can lead exceptional candidates to entry level positions in academia, government or the private sector. Full medical coverage (single or family), competitive salaries/stipends, sick leave, vacation, and maternity/paternity leave are offered with everyposition. Depending on the source of funding, other benefi ts are avail-able. Birmingham is a mid-size city centrally located in the southeast near beaches and mountains and enjoys a moderate climate for yearround outdoor activities and a cost of living rate lower than most met-ropolitan areas.
If interested visit our web site at www.postdocs.uab.edu, under Postdoc-toral Opportunities to view posted positions. Alternatively, you may sendus your cv and cover letter with four key words for research interests (pdfonly) to [email protected] and we will post this on our web site so that investigators may contact you. University of Alabama at Birmingham,
Offi ce of Postdoctoral Education, 205-975-7020.
Minority candidates are encouraged to apply.
Research Associateship Programs Postdoctoral Research Awards
Senior Research AwardsDavies Teaching Fellowships
offered for research in residence atUS Government Laboratories
��������� �������� ��� �� ����� �� ������ ������ �� ��������������������������� �� ������ ������
Questions should be directed to :National Research CouncilTEL: (202) 334-2760E-MAIL: [email protected]
Detailed program information, including instructions on how to apply, is available on the NRC Web site at :www.national-academies.org/rap
• 350 awards for independent research at over 120participating laboratories
• 12-month awards renewable for up to 3 years• Annual stipend $36,000 to $65,000 - higher for senior researchers• Relocation, professional travel, health insurance• Application deadlines February 1, August 1, November 1,
Opportunities for postdoctoral and senior research in all areas of science and engineering
����������� ����� ���
������������� �� ��� ����������� �������� �� �����
����������� ��������� ��� ������ �� ��� � ������
������ ��� ���������� �������� ����� ���� �� ������
�� � ���������� ������� �������� ����� �� ����
����� ���� ����� ��� ������� � ���� ����������
��������� ����� ���� ��������� ��������� �
����������� ���������� ������� �� �������� �� � �
������ ���� � �������� ������ �� ������ ���������
���� �� ���� ���� ������ ����� �������� ��
�� ����� �������� ����� !����� ����� � ���������
����� ����� ��� ���������� � ����������� �����
��� �������� ������� ������� ��"�� #��� ����
��������� � ���������� �������� ��������� �
���������� �������� �� ���������� �������� ���
����� ����������� �������� �� ������� �� �������
�� �������� � ������������ �������$��� �����%�
������� � �� � ����� ����� �� ��� ������� ���
��������� �������� ������ �� � ����������� �����
������ � ����������� ������ ����� � ������� �����
��� ����� ����� ��� ��������� � ������ ����������
�� ����� ��� �������� ���������� �� ����������
���� ������ �� ��� ���� ����� ���������� �� ���
��������� � �������������� �������� �� ���������
����������� ��������� ����������
&��� �������� � ��� �� ���� %���� �� ��� '� �� (���
������ � �������� �� �������� ���������
%�� ���� ������������ )* ���� � ��������� �������
&�� ������� ��� �������� �� ��� %��+� ������ '��
'���� �� (���� �� �������� ���� ��� ������ ������%�
����������
,� ��� ����� �� ��� ���� ������ �� ���������
������� �� ��� ��������� ����� �� ��� �������� ��
� �� ������������ ���������� �� ��������� � ����
��������� ������� 0���� ��� ���� �1 2������ ���
� ����������� ������ ������ �� �������� � ��������3
�� ������456������������������
�� �� ���� ����� � � ������ �� ������ �� �� ��������
�� � ������ � ����� � �� ��� �� ���� ������ ������ �
� ��� ���� �� ����� � ��� �������� ���� ����������� ����
����� ���� ��� ����� � ������� ����� ���������� �� � � ����
������� ����
�� �� ���� �� ����� �� ���������
PO
ST
DO
CTO
RA
L OP
PO
RT
UN
ITIE
S
Department of Health and Human ServicesNational Institutes of Health
National Institute of Diabetes and Digestive and Kidney DiseasesPOSTDOCTORAL FELLOWSHIPS IN DNA REPAIR AND RECOMBINATION AT THE NIHWe are a group of molecular and structural biologists whose main interests are in the areas of DNA repair and recombination. We are all located in a single building on the main intramural campus of the NIH in Bethesda, Maryland, a 20-minute ride from Washington, D.C. The intramural program of the NIH offers an outstanding research environment and many opportunities for collaborations. Applications are invited from individuals of the highest caliber with Ph.D., M.D., or M.D., Ph.D. degrees. The current research interests of the group include:
• Biochemistry and molecular biology of double-strand break repair and homologous recombination. Currentinterests include mouse meiosis (Mol. Cell 6:975, 2000; Dev Cell 4:497, 2003) and evolutionary genomics (Nat. Genet. 36:642, 2004). (Dan Camerini-Otero)
• Molecular mechanism of retroviral DNA integration. Biochemical, structural and functional analysis of HIV integrase and other proteins and nucleoprotein complexes involved in retroviral integration (http://orac.niddk.nih.gov/www/craigie/crahome.html). (Bob Craigie: [email protected])
• Structural Biology of Site-Specifi c DNA Recombination. Current interests include the Adeno-Associated Virus (Mol. Cell 10:327, 2002; 13:403, 2004), and other eukaryotic and prokaryotic recombination systems.(Mol. Cell 5:1025, 2000; EMBO J. 23:2972, 2004). (Fred Dyda: [email protected])
• Biochemistry and molecular biology of gene rearrangement in the immune system. Current work focuses on the RAG1/2 recombinase, its relation to transposases, and its covalent modifi cation (EMBO J. 21:6625,2002; PNAS 100:15446, 2003). (Marty Gellert: [email protected])
• Molecular Mechanisms of DNA repair. Current interests include the role of DNA mismatch repair proteins in homologous recombination and meiosis. (Nature 407:703, 2000; J. Mol. Biol. 334:949, 2003; Proc. Natl. Acad. Sci. 100:14822, 2003). (Peggy Hsieh: [email protected])
• Single-molecule biochemical study of macromolecular complex assembly/disassembly dynamics involvedin DNA transposition, site-specifi c recombination and related reactions. (Mol. Cell 10:1367, 2002). (KiyoshiMizuuchi: [email protected])
• Structural and functional studies of DNA repair (Mol. Cell 7:1, 2001; EMBO J. 19:5962, 2000), and rep-lication (Nature 424:1083, 2003; Mol. Cell 13:751, 2004). (Wei Yang: [email protected])
Interested candidates should send a letter stating their interests, their curriculum vitae and list of publications,and arrange to have letters from three references e-mailed to one of the investigators above or if you would like to be considered for more than one lab to: Dan Camerini-Otero ([email protected]) at: Bldg. 5, Rm. 201, 5 Memorial Dr., MSC 0538, National Institutes of Health, Bethesda, MD 20892-0538.
HHS and NIH are Equal Opportunity Employers.
Endocrine, Reproductive, and Developmental Biology-
Postdoctoral Fellow
CIIT Centers for Health Research, Research Triangle Park, NC is seeking a postdoctoral fellow in its Endocrine, Reproductive andDevelopmental Biology program to studycellular and molecular mechanisms of action of endocrine-active chemicals on reproduc-tive development. A Ph.D. in Endocrinology, Pharmacology, Toxicology, Molecular Biol-ogy, Biochemistry, or related discipline isrequired. Experience in cellular and molecularbiology, or biochemistry is preferred.
Interested applicants should send a completedPostdoctoral Fellowship Application Form(available from www.ciit.org), curriculumvitae, statement of research interests, andthree letters of recommendation to:
Human ResourcesP.O. Box 12137
Research Triangle Park, NC 27709-2137
Applications may also be submitted electroni-cally to: Dr. Kevin Gaido, 919-558-1236 [email protected].
CIIT is an EEOC Employer.
PO
ST
DO
CTO
RA
L O
PP
OR
TU
NIT
IES
POSTDOCTORAL FELLOWSHIP OPPORTUNITIES
The Santa Fe Institute (SFI) anticipates several openingsfor postdoctoral fellowships beginning in September 2005.
SFI research is devoted to complex phenomena drawinginput from a wide variety of fields, including biology (e.g.,genomics, evolution, ecology, immunology, biochemistry &cellular organization, systems & bioinformatics, structure of non-human social groups), computer science (adaptive & resilient computa-tion, novel forms of computation, simulation), physics and mathematics(nonlinear systems, statistical physics, biophysics), and the sciences ofhuman behavior (cognition, neuropsychological development, culturalevolution, market structure & function, evolution of human language).Applications are also welcome from disciplines other than those listed here.
SFI research is integrative, and there are no formal programs or depart-ments. Postdoctoral Fellows have the opportunity to work either onexisting research projects or on projects of their own initiation. Researchat the Institute focuses primarily on mathematical and computationalapproaches, although applicants whose research will include an experimen-tal or data-collection component in collaboration with off-site colleaguesare also encouraged to apply. Further details about SFI's current researchcan be found at <http://www.santafe.edu/indexResearch.php>.Postdoctoral Fellows are appointed for two-year terms on a full-time basis,with the possibility of a one-year extension contingent on funding andperformance.
Candidates should have a Ph.D. (or expect to receive one beforeSeptember 2005), with an academic record of scientific excellence, anability for independent research, and a strong interest in interdisciplinaryapproaches and collaboration.
Applications are welcome from candidates in any country. Women andminorities are especially encouraged to apply. Successful foreign applicantsmust acquire an acceptable visa (usually a J-1) as a condition of employ-ment.
TO APPLY: Please view the full position announcement and applicationinstructions at <http://www.santafe.edu/postdoc05.html>. All applicationmaterials must be received via post or electronically submitted no laterthan December 1, 2004. For further information, [email protected] or call (505) 946-2746.
SFI is an equal opportunity employer.
Postdoctoral Fellows Program in SustainableDevelopment of the Planet
The Earth Institute at Columbia University is the world’s leading academic centerfor the study, teaching, and implementation of sustainable development. It buildson excellence in the core disciplines—earth sciences, biological sciences, engi-neering sciences, social sciences, and health sciences—and stressescross-disciplinary approaches to complex problems. Through research, training,and global partnerships, the Institute mobilizes science and technology to advancesustainable development and address environmental degradation, placing specialemphasis on the needs of the world’s poor.
The Earth Institute seeks applications from innovative postdoctoral candi-dates interested in path-breaking disciplinary research as well asmultidisciplinary initiatives on sustainable development issues. ThePostdoctoral Fellows Program in Sustainable Development provides schol-ars with the opportunity to enhance their foundation in one of the Institute’score disciplines while at the same time acquiring the cross-disciplinaryexpertise and breadth needed to address critical issues related to reducingpoverty, hunger, disease, and environmental degradation.
Candidates for the Postdoctoral Fellows Program should submit a proposalfor research based in one of the core disciplines mentioned above that wouldcontribute to the goal of global sustainable development. This could take theform of participating in and contributing to an existing multidisciplinaryEarth Institute project, an extension of an existing project, or a new projectthat connects existing Institute expertise in novel ways. Candidates shouldidentify their desired small multidisciplinary mentoring team, i.e., two ormore senior faculty members or research scientists/scholars at Columbiawith whom they would like to work during their fellowship. Visit theInstitute’s Postdoctoral Fellows Web site (http://www.earthinstitute.colum-bia.edu/postdoc/) for a list of research units and relevant ColumbiaUniversity and Barnard College departments. Fellowships will ordinarily begranted for a period of 24 months.
More information on the program is available on the Postdoctoral Fellows Web site.
Application forms should be completed online at
http://www.earthinstitute.columbia.edu/postdoc/.
Applications submitted by December 1, 2004, will be considered for fellowships starting in the summer or fall of 2005.
For more information contact:
Hilary Cisneros DewhurstManager, Fellows Program
The Earth Institute at Columbia University405 Low Library, MC 4335
535 West 116th StreetNew York, NY 10027
E-mail: [email protected]
Columbia University is an affirmative action/equal opportunity employer.Minorities and women are encouraged to apply.
PO
ST
DO
CTO
RA
L OP
PO
RT
UN
ITIE
S
The National Institute of General Medical Sciences (NIGMS) inBethesda, Maryland is seeking applications from outstandingcandidates for one Health Scientist Administrator position in theDivision of Genetics and Developmental Biology which supportsbasic, non-disease-oriented research and training.
The incumbent for this position will be responsible for developingand managing a portfolio of research grants that emphasizesgenomic and post-genomic approaches to understanding basicbiological problems; a portfolio of grants in a related area ofgenetics, and some of the Division’s postdoctoral fellowships.The ideal candidate will have a broad background in geneticsand specialized experience in one or more of the following areas:human or mammalian genetics and genomics, proteomics, com-parative genomic analysis, and data management and analysis.
Applicants must possess a Ph.D. or M.D. plus scientific knowledgeand demonstrated expertise in at least one of the following areas:Biochemistry, microbiology, physiology, genetics, or relatedareas, and knowledge of the NIH peer review and grantsprocess. Salary is commensurate with qualifications, andincludes a full package of benefits. A detailed vacancy announce-ment (NIGMS-04-0005) with the mandatory qualifications andapplication procedures can be obtained via NIGMS web page athttp://www.nigms.nih.gov/about/job_vacancies.html and NIHHome page at http://www.jobs.nih.gov. Questions on applicationprocedures may be addressed to Erica Greene at (301) 594-2234.Applications must be received by close of business on October 15,2004.
Department of Health and Human ServicesNational Institutes of Health
National Institute of General Medical Sciences
DHHS and NIH are Equal Opportunity Employers
�� ����� � �������� ��
������������ ��� �����������
�������� ���
������������� �� ��� �������� ���������� ������� �����������
�������� ������� �� ������� �� ����� ��� ������� ���
������ �� ��� � ������ ������ ��� ����<����� �������� �����
������� � ���������� ������� ������� ����� �� �������� �����
������ �� ������� � ��� ��� � ������������ �� ��������
���� ����� ��� ������� � ���� ���������� &��� �������� � ���
�� ���� ����� �� ��� '� �� (��� ������ � �������� ��
�������� ��������� ��� ���� ������������ =( )* ���� �
��������� ������� �� �������� ���� ��� ������ ������ �� ������
���� � ��� ������ '�� '���� �� (����
>��� ��� �����+� ������ �������� ���������� �� � ������� �����
�� �������� � �������� ����� �������������� ���������
����� �� �������� ����������� �� ����������� �����?���
�� ������ ����������� ����������� ����� ������ ��� ������
� ��� ������ �� �� ������� ������� � ��� ���� � �������
�������� �� ������� ������ (������ � ��������� �� ��
������ ����� ���� � ����� � ��� ����+� ����� ��������
���� �������� �� ���������� �� �� ���� ��� ���������� ��
�� �� ����������� � � ������� ������������ ������ ���� ���
�������� ������� �������� ��� �� ���� ������� ��������
���� ����� ��� ���� � ������� ��������� �� ��������
(������ ��������� �� ���� � ���������� ������������
������� � �������� ��"�� �������� ������������ � ��������
������� �������� ��������� ������ ������������ �� � ������
����� 0��������� ������ ����� � ��������� ����� ����� �����
� ����������� ���������� ����������� �������� ������ ��
��������� ������� ������� ������@����� ��� ������ � ����
������� �������� �������� ������ ������� ��������� ���� ����
���� ��������� �� >(J� ������ ��� ����� �� ������� � ��
� ����� ����� �� ��� ������� ��� ��������� �������� ������
�� � ����������� ����� ������ � ����������� ,� ��� ��������
�� ������ ���������� ���?��� ��� ��������� ���� ������
������ �����������
0���� ��� ���� ��������� ����� 2������ ��� � �����������
������ ������ �� �������� � ��������3 ��
������456������������������
�� �� ���� ����� � � ������ �� ������ �� �� ������� �� �
������ � ����� � �� ��� �� ���� ������ ������ � � ��� ���� ��
����� � ��� �������� ���� ����������� ���� ����� ����
��� ����� � ������� ����� ���������� �� � � ���� ������� ����
�� �� ���� �� ����� �� ���������DEPARTMENT OF HEALTH AND HUMAN SERVICESNational Institutes of HealthNational Cancer Institute
With nation-wide responsibility for improving the health and well being of all Americans, the Department of Health and Human Services (DHHS)oversees the biomedical research programs of the National Institutes of Health (NIH) and those of NIH’s research Institutes.
POSTDOCTORAL POSITION TO STUDY THE MECHANISM OF PROTEIN FOLDING USING MULTI-DIMENSIONAL NMR. A post-doctoral fellow position is currently available in DHHS, NIH, National Cancer Institute (NCI), Center for Cancer Research (CCR). The goal of the project is to study the mechanism of protein folding using multi-dimensional NMR. Applicants should have some experiences with NMRand an interest with protein folding, structure, and function. Applicants should have a Ph.D. and fewer than 5 years post-doctoral experiences.
Please send a CV and bibliography, and a list of at least three refer-ences to:
Dr. Yawen Bai Laboratory of Biochemistry
CCR, NCI, NIH, Building 37, Room 6114E37 Convent Drive
Bethesda, MD 20892-4255 U.S.A.
or by e-mail: [email protected]
For additional information on the Laboratory of Biochemistry, CCR, NCI please see our website at: http://ccr.cancer.gov/Staff/Staff.asp?profi leid=5607
DHHS, NIH and NCI are Equal Opportunity Employers.
PO
ST
DO
CTO
RA
L O
PP
OR
TU
NIT
IES
LAWRENCE POSTDOCTORALFELLOWSHIP
The Lawrence Livermore National Laboratory (LLNL) has openings available under itsLawrence Fellowship Program. This is a highly desirable, prestigious postdoctoralposition with ample resources and freedom to conduct cutting-edge research in a fieldof the candidate’s choice. The duration of the Fellowship is up to three years. Typicallytwo to four openings are available each year. Fellowships are awarded only to candidateswith exceptional talent, credentials, and a track record of research accomplishments.
Candidates will do original research in one or more aspects of science relevant to themission and goals of LLNL which include: Physics, Applied Mathematics, ComputerScience, Chemistry, Material Science, Engineering, Environmental Science, AtmosphericScience, Geology, Energy, Lasers, and Biology. Successful candidates may participate inexperimental or theoretical work at LLNL, and will have access to LLNL’s extensivecomputing facilities, specialized laboratory facilities, and field equipment. A seniorscientist will serve as a mentor to each of the Fellows. The candidates will receive fullmanagement and administrative support. The salary is $7,583/mo.
Please refer to our web page http://fellowship.llnl.gov for eligibility requirements andapplication information. Please reference source code AJSC9H4DO. The deadline forapplication is December 1, 2004. LLNL is operated by the University of California forthe National Nuclear Security Administration/Department of Energy. We are an EqualOpportunity Employer with a commitment to workforce diversity.
http://jobs.llnl.gov
Assistant Professor PositionMolecular and Cellular Biology
Harvard University
The Department of Molecular and CellularBiology (MCB), Harvard University, has sev-eral openings for candidates for the position of Assistant Professor.
Our department covers a broad range of topics including cellular biology, developmental biol-ogy, molecular biology, molecular evolution,molecular genetics, neurobiology, and structural biology. We are particularly interested in candi-dates working in the following areas: cellularand molecular approaches to neural circuits,cell biological and evolutionary approaches to development, systems biology and the analysis ofgenome organization and function, mechanistic analysis of biological action at the molecular andstructural levels.
We strongly encourage applications fromwomen and minority candidates. Applications should include: curriculum vitae, reprints ofpublications, and a statement of present andfuture research plans (1-3 pages). Completeapplications and three letters of recommendation,solicited by the applicant, should be received notlater than 19 November 2004. Mail applicationsto: J. Blackbourn/MCB Search Committee,Department of Molecular and Cellular Biol-ogy, Harvard University, 7 Divinity Avenue, Rm. 127, Cambridge, MA 02138.
Harvard University is an Affi rmative Action/Equal Opportunity Employer.
www.mcb.harvard.edu
FACULTY POSITIONBioinformatics
Children’s Hospital Boston (CHB)Harvard Medical School (HMS)
andThe Harvard-M.I.T. Division of Health Sciences and Technology (HST)
The Department of Medicine at Children’s Hospital Boston and the Harvard-M.I.T. Divi-sion of HST at Harvard Medical School seek an outstanding Assistant or Associate Professor in Bioinformatics. Applicants should possessPh.D., M.D., or M.D./Ph.D. degrees and rele-vant postdoctoral experience. Areas of particularinterest include, but are not limited to: design and application of tools and databases for analy-sis of genomic sequences, transcriptional profi l-ing data and polygenic contributions to human disease. The successful applicant will enjoy an outstanding competitive startup package, excel-lent space and state-of-the-art core facilities, andwill be able to interact with existing Bioinfor-matics initiatives at CHB, HMS and MIT. Send CV and description of research and teachinginterests, and arrange to have three letters ofreference sent by October 15, 2004 to:
Isaac Kohane, M.D., Ph.D.Director, Children’s HST
Informatics ProgramChildren’s Hospital Boston
300 Longwood AvenueEnders 6
Boston, MA 02115
CHB, HMS and HST are Equal Opportunity Employers.
POSTDOCTORAL OPPORTUNITIES
POSTDOCTORAL OPPORTUNITIES
The Sallie Rosen Kaplan Fellowship is an opportunity for women postdoctoralscientists in cancer research, made possible by a generous bequest to the Foundationfor NIH (FNIH). Candidates for the Kaplan Fellowship must possess a doctoraldegree, have less than 5 years postdoctoral research experience, and have U.S.citizenship or U.S. permanent residency (green card). Fellowship training at theNCI can serve as a first postdoctoral assignment, or offer more experienced post-doctoral scientists an opportunity to further their training. The starting date will beno earlier than May 1, 2005 and program duration is normally 2 to 5 years.
NCI’s Maryland campuses boast the best funded and equipped research facilities inthe United States. Postdoctoral fellows have the opportunity to interact with inter-nationally renowned scientists from a wide range of disciplines. Fellowship stipendsare $37,100 to $56,200 commensurate with level of experience. Kaplan Fellowfirst-year stipends will be augmented with funds generated by the bequest.Standard self and family health insurance is provided and high-option coverage isavailable.
Applications and supporting letters must be received by December 15, 2004.Applicants are required to apply online. For eligibility information and applicationinstructions for this special opportunity, please go to our training and employmentWeb site http://generalemployment.nci.nih.gov or contact: NCI Office ofWorkforce Development, phone: 301-435-8524, fax: (301) 402-3509, e-mail:[email protected]
DEPARTMENT OF HEALTH AND HUMAN SERVICESNATIONAL INSTITUTES OF HEALTH
SALLIE ROSEN KAPLAN FELLOWSHIP
FOR WOMEN IN BASIC, CLINICAL, EPIDEMIOLOGICAL
OR PREVENTION SCIENCE
DHHS, NIH and NCI are Equal Opportunity Employers
Postdoctoral Positions Available
American Society for Microbiology and National Center for Infectious Diseases
2005 Postdoctoral Research Program
Up to ten associate positions will be awarded by the American Society for Microbiology for full-time research on infectious diseases which cause signifi cant public health problems. Associates will perform research in residence at the National Center for Infectious Diseases (NCID) which is headquartered at the Centers for Disease Control and Prevention (CDC) in Atlanta, GA. In addition to Atlanta, NCID operates laboratories in Ft. Collins, CO, Anchorage, AK, and San Juan, Puerto Rico.
Eligible fi elds of study include: Bacterial and Mycotic DiseasesViral and Rickettsial Infections
Nosocomial Infections HIV/AIDS
Vector-borne Infectious Diseases Sexually Transmitted Diseases
Parasitic Diseases
The associate positions are limited to individuals who either earned their doctorate degree (Ph.D., Sc.D., M.D., D.V.M., or D.D.S.) or have completed a primary residency within three years of their proposed start date. The program provides an annual stipend of $35,800, health care benefi tspackage and up to $4,000 for professional development.
The application deadline is November 15, 2004. For more information, visit ASM’s home page at http://www.asm.org/Education/index.asp?bid=15497 or e-mail: [email protected]. The brochure and application are available on line.
American Society for Microbiology Centers for Disease Control and Prevention National Center for Infectious Diseases
UNIVERSITY OF CALIFORNIASAN FRANCISCO
Lung Biology
A faculty position in UCSF’s CardiovascularResearch Institute (CVRI) is available. The suc-cessful candidate will be expected to establish an exciting independent research program andto contribute to CVRI and graduate training pro-grams. Laboratory space and salary support will be provided by the CVRI. A primary academic appointment in an appropriate basic science or clinical department at the Assistant, Associate, orFull Professor level and membership in UCSF’s graduate programs will also be provided. Indi-viduals working in any system (Drosophila tohuman) and any area broadly related to pulmo-nary biology will be considered. Possible topics include, but are not limited to, invertebrate airwaydevelopment, mammalian lung development,epithelial cell biology, airway-related innate and adaptive immunity, and the genetics and patho-physiology of pulmonary diseases. Candidates foran Assistant Professor appointment should hold aPh.D. or M.D. and have substantial postdoctoral experience.
By October 31, 2004, please submit curriculum vitae, summary of research accomplishments andplans, reprints of major publications, and three tofi ve letters of recommendation to: Hal Chapman,M.D., c/o Julie Tom, CVRI, (Search# M2508), 505 Parnassus Avenue, M1316, University of California, San Francisco, CA 94143-0130.
The University of California, San Francisco is an Equal Opportunity/Affi rmative Action
Employer. Women and minorities are encouraged to apply.
UNIVERSITY OF CALIFORNIASAN FRANCISCO
A faculty position in UCSF’s CardiovascularResearch Institute (CVRI) is available. The suc-cessful candidate will be expected to establish an exciting independent research program and tocontribute to CVRI and graduate training pro-grams. Laboratory space and salary support will be provided by the CVRI. A primary academic appointment in an appropriate basic science orclinical department at the Assistant, Associate, orFull Professor level and membership in UCSF’s graduate programs will also be provided. Indi-viduals working in any system (from C. elegansto human) in any area broadly related to cardio-vascular biology and disease will be considered. Target areas include cellular signaling, molecular imaging at the cell and tissue level, developmentalbiology, vascular and cardiac biology, genetics/genomics, including human genetics, molecular physiology and disease-focused programs. Out-standing candidates working in other areas will beconsidered. Candidates for an Assistant Professorappointment should hold a Ph.D. or M.D. and havesubstantial postdoctoral experience.
By October 31, 2004, please submit curriculum vitae, summary of research accomplishments and plans, reprints of major publications, and threeto fi ve letters of recommendation to: Shaun R. Coughlin, M.D., Ph.D., c/o Julie Tom, CVRI, (Search# M-2254), 505 Parnassus Avenue, M1316, University of California, San Fran-cisco, CA 94143-0130.
The University of California, San Francisco is an Equal Opportunity/Affi rmative Action
Employer. Women and minorities are encouraged to apply.
POSTDOCTORAL OPPORTUNITIES
POSTDOCTORAL OPPORTUNITIES
SCIENTIFIC LEADERSHIPPOSITIONS AT ROSWELL PARK
CANCER INSTITUTE (RPCI)As part of an ongoing scientific expansion, RPCI is seeking nationally-recognized leaders in three key research areas described below. Duringthe past five years, RPCI has undergone major changes including thehiring of approximately 100 new senior scientists and clinicians. A newgovernance structure, initiated in 1999, allows for unprecedentedadministrative flexibility and competitive compensation and benefits.An expanded academic program offers graduate training to approximately180 doctoral and masters students at any given time. A $240 millionmajor modernization effort led to a new, state-of-the-art hospital and a160,000 sq ft medical research complex. In addition, RPCI’s new170,000 sq ft Center for Pharmacology and Genetics will open inJanuary 2006, adjacent to the new University at Buffalo Center forBioinformatics & Life Sciences and the Hauptman-Woodward InstituteStructural Biology Research Center.
At RPCI, basic scientists and clinicians interact in a cancer-focusedenvironment organized into five major research programs supported byan NCI Cancer Center Support Grant (CCSG). Each program emphasizesmission-oriented research culminating in the clinical validation of basicscience findings and concepts. In addition to Departmentaladministration, successful candidates are expected play a leadershiprole in their respective CCSG program. All applicants should havesubstantial and sustained funding.
CHAIR, MOLECULAR PHARMACOLOGY &THERAPEUTICS
The Therapeutics Department is comprised of 20 scientists and clinicianswith interests in target discovery, drug action and resistance and therapydevelopment. Possible areas of applicant research could include, but arenot limited to, pharmacogenomics, proteomics, targeted therapies, drugaction and resistance, and mechanism-based drug combinations. Inaddition to developing Department research by recruitment andcollaborations, the successful candidate will be expected to coalesceopportunities for target discovery and exploitation being generated bythe Genetics faculty and the Center for Bioinformatics, and to expandinteractions with the nearby University at Buffalo.
CHAIR, CELLULAR STRESS BIOLOGYThe Cellular Stress Biology Department at RPCI is comprised of 11scientists and clinicians and focused on radiation therapy, photodynamictherapy and cellular stress responses supported by two P01 awards.Successful candidates will be expected to expand existing programmaticefforts through collaboration and recruitment and to complement clinicalresearch activities by furthering translationally focused researchinteractions. Areas of research being sought include, but are not limitedto, radiation biology, proteomics, photodynamic therapy and oxidativestress biology.
HEAD, DIVISION OF MOLECULARPATHOLOGY
RPCI is establishing a Division of Molecular Pathology which willsupport a research interface between clinical and basic science programs.Areas of applicant interest should include biomarker development, geneexpression profiling, proteomics or image analysis. The successfulcandidate will recruit additional faculty in building a strong andcollaborative research team responsible for bridging basic and clinicalresearch efforts.
Each position will be provided withcompetitive space and financial resources forfurther development of Departments andCancer Center Programs. Applicants shouldsubmit a CV that includes funding record,three references, and a cover letterindicating the position of interest to:Michael Brattain, PhD, Senior VicePresident, Basic Research, Roswell ParkCancer Institute, Elm & Carlton Streets,Buffalo, NY 14263, Fax: 716-845-4437,email [email protected].
Roswell Park is anEqual Opportunity Employer
UNIVERSITY OF CALIFORNIA, RIVERSIDE
DEAN
BOURNS COLLEGE OF ENGINEERING
The University of California at Riverside, invites applicationsand nominations for the position of Dean of the BournsCollege of Engineering. UC Riverside offers undergraduateand graduate education to nearly 18,000 students and hasa projected enrollment of 21,000 students by 2010. It isthe fastest growing and most ethnically diverse campus ofthe preeminent ten-campus University of California system.
The Bourns College of Engineering is one of the mostrapidly expanding engineering schools in the country. It isnow on the cusp of a new era for the Riverside Campus.Founded just 15 years ago, the College has 70 faculty andapproximately 2,000 students with continued growthexpected over the coming years. The College is composedof four departments: Chemical and EnvironmentalEngineering; Computer Science and Engineering; ElectricalEngineering; and Mechanical Engineering. The College’sphysical plant will double in size to 310,000 sq. ft. with thecompletion of a new engineering building for ComputerSciences and Electrical Engineering. We expect the Collegeprograms to grow in size and complexity in the areas ofNanotechnology, Bioengineering and Material Science. Moreinformation about the College of Engineering and theUniversity can be found at www.engr.ucr.edu/deansearch.
Major responsibilities of the Dean include academicplanning, fiscal management, faculty development, industryrelations, and fund raising. Because of the relative youth ofthe College, program development at both theundergraduate and graduate levels will also be a primaryresponsibility. The Dean reports to the Executive ViceChancellor/Provost.
The University seeks energetic, highly motivated andvisionary candidates. Essential requirements include arecord of distinction in scholarship and the profession,significant management and leadership experience,demonstrated experience in strategic planning, andeffectiveness in building collaborative programs across theacademic enterprise and with industry and government. TheUniversity of California, Riverside, has a strong institutionalcommitment to the achievement of diversity among itsfaculty, staff, and students and seeks an individual whoshares that commitment.
Salary will be commensurate with experience andqualifications. The starting date is July 1, 2005, or asnegotiated.
Review of candidates will begin November 1, 2004; theposition will remain open until filled. Applications andnominations should be addressed to:
Professor Jerome S. Schultz, ChairBCOE Dean Search Committeec/o Sharon Vander Veen
Office of the Executive Vice Chancellor and ProvostUniversity of California, Riverside
Riverside, CA 92506
The University of California, Riverside, is an equalopportunity/affirmative action employer committed toexcellence through diversity.
������ �������� ��� ������� � ����������� ����������
��� ��� ����
�������� �����������������
�������� ����� �� ��� ����� �� ����
� ����� ������ ��!�" #�"����!#! $% ��$�$��"�� %'�"(�$� �( �(! "$*�+ (��
��(��(�$� �! (��( ��; <��� ��!$ =*$#$(� (�� >����$=#��( $% ��< �#���
��� ��> $(��* #�(�$>! ($ (*�"? ��> #���='��(� #$��"'��! �� ����� ��> ��
������ "���!+�! <��� �! ��< ����(�"� ��> >*'����!�> #�(�$>! ($ !���"(����J
���"(���(� $* �"(���(� =�*(�"'��* #$��"'��! �� !=�"�L" "���! �( >�!����(�>
(�#�!Q ��� ��; <��� �� �$'!�> �� � ��<+ T�"��*> ����*X>�!����>
Z[�+������� ��%� �"���"� ��"��$�$�J ;'��>��� \($ �� $""'=��> �� Z��[]
<��*� (�� "$*� ��!(�('(� %�"'�(J <��� �� "$#=��#��(�> �J+ ��> �� �##��
>��(� ^'_(�=$!�(�$� ($+ %�"'�(J <�$ �*� >����$=��� ��$=�J!�"��+ "��#�"��+
"$#='(�(�$���+ ��> �������*��� �==*$�"��! (��( "�� �� �*$'��( ($ ���*
$� ������#=�"( `'�!(�$�! �� ��!�" ��$�$�JQ $*���� �! =*�!��(�J !��*"����
%$* � >�*�"($*Q�==��"�(�$�! %$* !���$* ��> ^'��$* %�"'�(J =$!�(�$�! �� (��
��< ��!(�('(� <��� �� !$��"�(�> �� (�� ���* %'('*�Q
� �� ������ � � ���� ���� ���������� ��=�*(#��( $% �$��"'��* ;�$�$�J j {���(�"! !��?! (<$ (��'*��(*�"?
�!!�!(��( =*$%�!!$*! $% "��� ��$�$�J ��>|$* >����$=#��(�� ��$�$�J !('>J���
(�� %'�"(�$��� $*����}�(�$� $% "���! $* (�!!'�!Q���!� =$!�(�$�! �*� =�*( $% �
"�#='!�<�>� �_=��!�$� �� "��� ��$�$�J \!��~��!(�('(� $% �$��"'��* ��> ���
;�$�$�J� ���$���]Q�$* $�� $% (�� =$!�(�$�!+ (��*� �! =*�$*�(J %$* (�� '!� $%
(�� #$'!� �! � #$>�� $*����!#� (��! �! =�*( $% (�� "�#='!�<�>� ���(��(���
�� #�##����� ���$#�"!Q ��"� !'""�!!%'� "��>�>�(� <��� �� �_=�"(�> ($
�!(����!� � ���$*$'! ��>�=��>��( *�!��*"� =*$�*�# ��> =�*(�"�=�(� �� (��
(��"���� $% "��� $* >����$=#��(�� ��$�$�J �( �$(� �*�>'�(� ��> '�>�*�*�>'�
�(� �����!Q��� >�=�*(#��( ��"�'>�! %�"'�(J <�(� *�!��*"� =*$�*�#! �� "���
��$�$�J+>����$=#��(�� ��$�$�J+����(�"!+#$��"'��* ��$�$�J+"$#=�*�(��� ��>
=$='��(�$� ���$#�"!+ !(*'"('*�� ��$�$�J+ ��> ��$"��#�!(*J \�==>���???�@����ABC�DD���E]Q ��>�>�(�! !�$'�> !'�#�( �==��"�(�$� #�(�*���! ��>
�**���� %$* (�*�� ��((�*! $% *�"$##��>�(�$� ($ �� !��( ($��$�J ;*�(!"��*+
���|�����$=#��( ���*"� $##�((��+ ��[ ;�$(�"��$�$�J ;�>�Q+ $*����
����*!�(J+ �(��"�+�� �����Q�==��"�(�$�! "�� ��!$ �� !'�#�((�> ���"(*$���
"���J �! ��� L��! ($ ������ABC�DD���EQ��� "$##�((�� <��� ����� *����<���
�==��"�(�$�! $� �"($��* ��+ Z���Q
���� ����� ����� ����$*���� !��?! %�"'�(J <$*?��� �( (�� ��(�*%�"� $% �������*��� ��> ��%�
!"���"� <�$ (�*��� $� ��(�*>�!"�=����*J *�!��*"� ��> (��"����Q $*����
��! %$*#�> � ��< ��=�*(#��( $% ;�$#�>�"�� �������*��� \;��] (��(
!��?! ($ �*�>�� #�>�"���+ ��$�$�J+ ��> �������*���Q��� >�=�*(#��( �!
�'�>�> �J � ��!�$� $% >����$=��� � `'��(�(�(��� '�>�*!(��>��� $% (��
�'#�� �$>J �"*$!! !"���! �! � ��!�! %$* (�� *�(�$��� >�!��� $% >���"�!+
>����$!(�"!+ ��> (��*�=��! ($ �#=*$�� �'#�� ����(�Q ;�� �! *�!=$�!����
%$* �*��(��� ��|��� ��> ���� >��*��! ��> !=$�!$*! �� '�>�*�*�>'�(�
#��$* �� ;�� ��������� ($ ��� !('>��(! #�^$*��� �� �������*���Q�<$ (��'*��
(*�"? %�"'�(J =$!�(�$�! �� ;�$#�>�"�� �������*��� �*� ��������� <�(� *��?
$=��QT�!��*"� �� ��J �*�� $% ��$#�>�"�� �������*��� <��� �� "$�!�>�*�>+
��(�$'�� (��*� �*� =�*(�"'��* ���>! %$* %�"'�(J <�(� ��(�*�!(! �� "���'��*|(�!�
!'� ��$�������*���+ #$��"'��*|"���'��* �#����� (�"��$�$�J+ ��$#�(�*���!+
!J!(�#! ��$�$�J+ ��> �==��"�(�$�! $% #�"*$|���$%��*�"�(�$� �� #�>�"���Q
$*�����! ��(�* %$* ��(�*���! T�!��*"�+ ���$��$(�"��$�$�J ��(�*+
��(�* %$* ���$%��*�"�(�$�+�����$=#��(�� T�!$'*"�
%$* ;�$=�J!�"�� �#����� ��> �=($����"(*$��"!+ ��>
���$*J ��(�* =*$��>� $'(!(��>��� %�"���(��! ($ !'=�
=$*( ��(�*>�!"�=����*J *�!��*"� *������( ($ ��$#�>�"��
�������*���Q��>�>�(�! !�$'�> ���� � ��� �� ;�$#�>��
"�� �������*��� $* *���(�> (�"���"�� L��>Q ��(�*�!(�>
"��>�>�(�! !�$'�> !��> � ��((�* $% ��(�*�!(+ �������������+�*��% !(�(�#��( $% *�!��*"� ��> (��"���� ��(�*�!(!+
=����*J !('>J $% $*����!#! �� (�� =$!(����$#�"! �*�Q���! %�"'�(J�>*����
�%%$*( !�*��! ($ ��(��*�(� (�� ��%� !"���"�! <�(� $*�����! $'(!(��>���
=*$�*�#! �� (�� =�J!�"��+�������*���+��> "$#='(�(�$��� !"���"�! (�*$'��
�� ��(�*"$���"(�>+"�#='!�<�>� %$"'! �*��! "$#=$!��� � � ��! �� �� " ��������� Q ������ ���'� �� ���� ��> �_(��>��� (�*$'�� (��
��_( L�� J��*!+ $*���� �! �� (�� =*$"�!! $% #�?��� ��� =*$%�!!$*���
�==$��(#��(!+ �!(����!���� � ��< �*�>'�(� %���$<!��= =*$�*�#+ "*��(���
��< *�!��*"� "$*� %�"���(��!+ ��> �'��>��� !���*�� #�^$* "�=�(�� =*$^�"(!Q
�"(��� %�"'�(J !��*"��! �*� ��!(�> $� (�� ��_( (�*�� =���!Q �$* #$*�
��%$*#�(�$�+=���!� ��!�( $'* <��!�(�!��==>���???���CA@F�G��ABC�DD���E�+ �==>���DF��G�F�C��G��ABC�DD���E���AE=�FCF=F�=FH��>�>+
��> �==>���HFHA�DF�B�BI��ABC�DD���EQ
� ���� ����#" �! ���� �� ���� �"���+<��"� $��*�$$?! ���#����
�$�� �J'�� ��?�+ �! �$"�(�> �� (�� �����* ��?�! *���$� $% =!(�(� ��<
�$*?+� !"���" ����*$�#��( $% !=�"(�"'��* ��?�!+<�(�*%���!+�$*��!+*$�����
����!+ %�*#���>+ ����J�*>!+ ��> !(�(� =�*?!Q �( �! �� �*�� <�(� $'(!(��>���
*�"*��(�$��� ��> !'##�* ��> <��(�* !=$*(! $==$*('��(��! %$* ��>���>'�
��! ��> %�#����!Q��� $*���� "�#='! �(!��% �! $�� $% (�� #$!( ���'(�%'�
�� (�� "$'�(*JQ �! � =*���(� ��>$<�> '����*!�(J (��( ��"�'>�! !���*��
!(�(���!!�!(�> "$�����! ��> ��!$ �! (�� !(�(��! %�>�*�� ���>��*��( ��!(�('�
(�$�+ $*���� "$#=*�!�! �� '�'!'���J ��*��> �**�J $% �"�>�#�" '��(!Q �( �!
� #�#��* $% (�� ��J ����'�Q��� �(��"� "$##'��(J �! "'�('*���J >���*!�
<�(� �_"�����( (���(�*+#'!�"+!=$*(!+��> $(��* �"(���(��! ��L((��� � #�^$*
'����*!�(J ($<� J�( ��! (�� <�*#(� ��> %*���>����!! $% � !#��� "$##'��(JQ
��� �*�� �! ?�$<� %$* �(! #��J �$$?!($*�! ��> *�!(�'*��(!+�� �_(��!���
<��?��� (*��� !J!(�#+ �*�$*�('#+ $*��(�$�$�J $�!�*��($*J+ #�*���+ %�*#�
�*!� #�*?�(+ � ���>!�$� �"���"��(�*+ ��> �*( ��> !"���"� #'!�'#!Q �$*
#$*� ��%$*#�(�$� ��> ���?! ($ ��>���>'�� �((*�"(�$�! ��!�( �==>���???�HFGF=F=������A@��A@����@Q
��� �� ������ ���!! $(��*<�!� �$(�>+ �==��"��(! !�$'�> !��> �
"$��* ��((�* !(�(��� (�� =$!�(�$�\!] %$* <��"� (��J <�!� ($ �� "$��
!�>�*�>+ � �������� �����+ � "$�"�!� !(�(�#��( $% *�!��*"� =���! ��>
(��"���� ��(�*�!(!+ "$=��! $% *������( ='���"�(�$�!+ ��> (�� ��#�! $%
�( ���!( (�*�� *�%�*��"�! ($� ��< ��%� �"���"�! ���*"� $##�((��+
$*���� ����*!�(J+ Z�� �#�*!$� ����+ �(��"�+ �� �����X���� \�#����
�EDF��G�F�C��G��ABC�DD���E� =�$��� ��[XZ��X[Z��� %�_� ��[XZ��X
����]QT����< $% �==��"�(�$�! <��� ����� �$��#��* �+Z��� ��> "$�(��'�
'�(�� (�� =$!�(�$�! �*� L���>Q$*���� ����*!�(J �! �� �`'�� $==$*('��(J+
�%L*#�(��� �"(�$� �>'"�($* ��> �#=�$J�*Q
���� �� ��"���#� �! $�� �#��� ��� � �� �������$*���� ����*!�(J �! "*��(��� � ��< ��!(�('(� $% �$��"'��* ��> ��� ;�$�$�J
\��;] (��( ��! �! �(! �$�� (�� ����!(���(�$� $% %'�>�#��(�� ��$�$��"�� =*$�
"�!!�! (��( ��� �( (�� "��(�* $% ��%� ��> "���'��* %'�"(�$�Q��� ��< ��!(�('(�
<��� !�*�� �! � %$"�� =$��( %$* *�!��*"� �%%$*(! ����� ='*!'�> �� ��%� !"���"�
>�=�*(#��(! �"*$!! "�#='!+ *������ %*$# ����(�"! ��> ��'*$��$�$�J ($
=���( !"���"�+ ���#�� !"���"�+ ��> ��(�*���*J #�>�"���Q
� ?�J �!=�"( $% ��; <��� �� !(*$�� ��(�*>�!"�=����*J
��(�*�"(�$�!Q��� ��; <��� %$"'! $� (�*�� ?�J ��$�$���
"�� =*$"�!!�! (��( $""'* �� � *��'��($*J !'""�!!�$��\�]
"���'��* !��������+ \Z] (�� ��(�*=*�(�(�$� $% (��!� !�����!
�( (�� ����� $% ���� *��'��(�$� ��> �_=*�!!�$�+ ��> \�]
(�� �_�"'(�$� $% (��! *��'��(�$� (�*$'�� "�����! ��
"���'��* !(*'"('*�+ >J��#�"!+ ��> %'�"(�$�Q
($ *�"*'�( %�"'�(J ��> =*$��>� *�!$'*"�! (��( %$!(�* (�� #'�(�>�!"��
�� ������� �������
�������
������ ���� ����
���� �� ���� �������� ��������� �������� �� ���� �� ������������� ��� ��������������� ��� ���������
��������������� ��� ������������������� �������� ������ ���������� ��� � ��������������� ������� � ��� ������ � �� ��� �������� ���������� �������� �� ��� �������� ��������� ���������� ��������� ���� ����������� �� ������������ ����� ��� � ������ �� �������� � ������!������"������� ��� ��� ������� ����� ������� �� ��� �������������� �������� ������� � ���������� ���������������� ������ ������#�� ���$��� ����� �� ��������� �� ���� ����������� ����� %������� �� ������������ �� �������� ������� �� ������ ������������ ��� ��������& (�) ���� � ����� "������� � *����������� ������ ��$�� �������� �� ��� �"���� �� ���� ���� ��������� ����� �� ��*������ ��� ������� ���� ���������� ���+�� ������� �� ���� � ����� ������� ��������� ������ ���� ������� ������� �� ������� �� "� ��� )�������� �� ,�������� - ����������� �������� � ��� ������� �� &��������� �� .��� 1�����&������� ������ ��"��� � ������ �� ���������� ���������� �� ������ ����� �������� 3������ ���������� ���� �������� ��"���� ������� ���������4 ��� ,��� &���� 1���� ���������� ,������������ �� ,���������� 5��������� ,�������� - ���������� ���������89: !��� �!�"" ;���� ������ �������� � 5����� <=� >?@A8BAC:>������� "��� �������� ���������� 1�����"�� >A�9::?�D�� ���� ����������������� ������������ ��� ��� �������
�������������� ������������ ��� !���������� "����������������� ���������� ��� ������������� ������� �� � ���������������� ���� ��� � � ����� ���� � ������E� <�� .��� 1���� 5������������� ��� ��������� � ,� ���� ���������� "������������ ������������ ������� ������������� �� ��������������������� ����� ��������� ������� �������������� ��������� �������� ��� �������� ��������� "��+������ � ���� �� ������ ������������� ����"���������� ��� ������ ������� �� +�� �� ��� ������� �� ��� �������� ��������� ����� � ������� �� "������������ ����������� ������� �� ���������� �������!�*�������� ����� � (�) � ������� �������� "����� � "��������� �"������������������� ���������������������������� ������� ���� ��������������� ������� ������������ � �������
������������� ������� ��� ����������������� )�������� ���������� 1��� �� ������ �������� �� ��� ���� ��� ������������� ���������� �������� � ����������� "����� � &������� ������ ����� ��� ����� "������� � ������� ���� �� ������ ���� ���� ������ "������� �� ������� ������� � ����������� ������ ��"����� � !������ �� ����� ��� ����� �� ���������� �� ���������"����� "������������ "�������� �������� �� ��������� "����� ��� ��� ������ ��� �������� ���� ��������� ������� ���������� ��� �������� �� ������� � ������ ������� ����������������� �� ����������� " ��� F�+� �� �������� - 5��������1��� 3�514� � ������ ��� ���� � �������� ����� �������� � ���D���� �� �������� - 5�������� 1��� ���� � ��������� ������������ �������� ��� ���� ���� �� ��� ���������� <�� .���1���� 5�������� �� ������ ���� �������� ����� ������������ ����������������� ��������
D������ ��������� �"��� ��� ��������� �� ��� F�+� �� ��������- 5�������� 1��� �� ������"�� �� �������������� �������� ����������������� ���������� &������� ������ ��"��� � ������������� �� ��� ���� �� �� ����� ����� �������� ���������D���� !�������� ���������� )�������� �� �������� 1���� ?>8: ���� ;���������� �������� � 5����� <= >?@A8BCA:>�
#���� $��������� "������� % !�������������������� ������ ���� ��������� � ���� ���������� ������� ���������� ������� ��$�� ���������������� �� �������� � ��������� ��� ������������� ���� ����"������ �������� ��������� ������������� � �� ����"��� �������� �� ���� �� ������������� �� ���������� ��� ����� �� ��������� �������� � ���� ����"����� �� ���� ������� �� �������� ���� ���� ����� ������� ��
����"��� ������ � �� ����� �� �������� � ��� ���� �� �������������� ������������ ������� �� ���������� �� ��� ���������� �������� ��������� ����� � ��� )������ �� <���������1����� 1������� �������� ���� "� ��������� ���� � ��������� �������� ��������� ������ G����� - )����������
,��������� - %������� ,����� � �� ������������ ,����� �
&�� �������� % $������� �������� '��������� ���� �������� ��� ��� �������� ��������� �� ������� "��������� *������� �� ��� ������ ���� � ����� "���� � "����������������� H� ����� �� ������� ������ "�� ��� �� ������� ���
(�� ����� � )�������� !�����'��������������� �������� ��&���� ����� *� +������ ��� ,���� �������� $������� �����������(������������� ��������� ��� �� ���������������� ����������*��� ��"��� ���� ����� �������� �� ������ ��� � ������ �������� �� ����� �������I��� ��������� �� ���������� ��#������� ������� �� ������ ������ ������ �� ����������������������I �� ��� ��������� �� ������ � ������ �� ����� �������� ������������ �������� �� ����������
,��+��������� �� $��*��� )�������� ��������� ��� $�����-����� �������� ������ ��� ���� �� ���������� �� ����� ��������" ����� ����J���� ����� ���� ������� � �� ������ ������� I�������� ���� �� � ������ �������� �� ���"� �������� ��� ����I �� ��� ��������� �� ������ ����� �� ���������� ������������� ����������
(�� "��������� �+������ )�������� ��� ������� '�����������)���� ���� �� !��������� ���������� �������������� �������� ���������� ��������������� ���$�� ��� �� �� ���������� � ��� ������� ����#������ ��� ����� �� "�����������I ��� ����� �� ���� ���� ���I�� ��� ����"������� �� �� �� � �� ������� ������� ��������� " ��������J ���� �� �������� ������ � ������ ����"��� �� �������
(�� ���������� � ,�� ������������� )����� ��� +���-������ �� ������ /��������� ���������� ���������� ��� ������������ ��� !������ !����������� 0*����������������������� ���������� ��� ������ � ���� �� ��� ��������� ������� ����������� ��������� ��� ��� �� ���������� �� ������������ ��� ��� �� "����������� �� ���������� ������ �� ����� ������������ "����� � ����� ��� ���� �� ��������� "����� � &�� ����������� ���������� �� K���� �� ����� ������� ��������� ������ ������ �� �� ��� �����"�� ���� ���������� � ����� ���� �������
)�������� ���������� ��� ���������� "������������� �� �������� �� "������ �������� ���������� �������� ��������� ����������� �������� ��������� ������� ��� ����������� ����� ��� ������� ��������������� � �������� � �������� �������������� ������� �� ���� ������� � "��� �� ����� ������� "����� � & �� ����� ���L����"���� G����� ��� "�� ����"�������� ������� ������� �� ������ ��� �������� ��� �� �������� ������������� ������������
���� ���� ����� �������� � %������� G����� ���� �������� ���� ������ ���� ��������J�� ��� ��� �� ��� ����� �� � ������������� ;������� ��������� �������� ���� ����� �������� �������"���� � ����� ���� "� ������������ �� ��� ��������� � �������%�� ������������ ������� �� � ,������������ ��� ����������������� � ���� ������ ����� ��� ����� ����
$������������ "����������� �������� ������� ���� ��� ������������� ��������� ������� ��� ���� �� �� ��������� �������� �� ���������� ���������� ��������� ������ "�� ��� �� �������
��� ��� ��� ���� ��� ��������� ���+���� �� ����������� 5���� �������� ���� ��� ��� ������"�� ����� ����� ������� � ������� +���� �� �������������������=��� ,������� 3���� ��������4��� ���� ����������
���������� "��������M���� �� ����� ����������� ������"�� �� ��� ,���� 5������� ���&���� ;����� ������������� ���� �� ����� ������� �� ��� �����
�������
$*����}�(�$� $% >$#�!(�" #�##����� !=�"��!Q�==��"��(! <$*?���
�� (�� "����� !J!(�# �*� =�*(�"'��*�J ��"$'*���> ($ �==�JQ$�(�"(
�$'� ��("}�? \�������������"] %$* #$*� ��%$*#�(�$�Q
��� =$!�(�$�! �*� ��������� �� (�� >�=�*(#��(! $% ;�$#�>�"�� �"��
��"�!+�$��"'��* ;�$�$�J j {���(�"!+���#�� �"���"�+�$��"'��*
��>�"���+ ����"�� �"���"�!+ ��> (�� ;�?�* ��!(�('(� %$* ���#�� ����(�Q
��>�>�(�! !�$'�> ���� ���+ ��+ ��>|$* ��� >��*��!+ �� "$##�((�>
($ >����$=��� � !(�(��$%�(����*(+ �_(�*����J %'�>�> *�!��*"� =*$�*�#+
��> �� #$(���(�> ($ =�*(�"�=�(� �� (�� '����*!�(J�! (��"���� ��> ='���"
!�*��"� #�!!�$�!Q��� =$!�(�$�! �*� (��'*��(*�"?+ ��������� �( ^'��$* ��>
!���$* �����!+ ��> ��"�'>� "$#=�(�(��� !(�*(�'= =�"?���!Q�$ �==�J+ !��>
\=*�%�*���J �! � ��� L��] J$'* ���������� ���+ !(�(�#��( $% *�!��*"�
=���!+ ��> � "$��* ��((�* !=�"�%J��� $�� $% (�� �*��! ��!(�> ��$�� ($�
�$�� �"��#��(� \$�% ������������"]+ ��##����� {��$#�"! �$"'!
{*$'=+$����� $%��(�*���*J ��>�"���+$*���� ����*!�(J+�������T�+
�(��"�+�� �����Q��!$+�**���� %$* (�*�� ��((�*! $% *�%�*��"� ($ �� !��(
!�=�*�(��J \���! =*�%�**�>]Q{���*�� ��%$*#�(�$� $� $*�����! �$���(�*#
*�"*'�(��� $�^�"(���! �� ��##����� {��$#�"! "�� �� $�(����> (�*$'��
(�� !�#� "$�(�"(Q
��������� ��� �������� ������ $*���� ����*!�(J ��> (�� ;$J"� ��$#=!$� ��!(�('(� %$* ����( T��
!��*"� \;��] ����(� �==��"�(�$�! %$* (<$ %�"'�(J =$!�(�$�! \$�� ^'��$*+
$�� ������$=��] �� �$��"'��* ��> ��#�"�� �"$�$�J \���]Q�� !��?
!"���(�!(! '!��� #$��"'��*+ "��#�"��+ ����(�"+ ���$#�"+ ��$"��#�"��+
��>|$* =*$(�$#�" �==*$�"��! ($ !('>J "��#�"�� ��> ����(�" ��!�! $%
��(�*�"(�$�! ��(<��� ���#��!+ =���(!+ ��> #�"*$��! ��>|$* ��(<���
$*����!#! ��> (���* ����*$�#��(Q T�!��*"� �*��! ��"�'>�+ �'( �*� �$(
��#�(�> ($� #$��"'��! (��( #�>��(� ��(�*�"(�$�!+ (�� *�"�=($*! ��>
=�(�<�J! (��( (*��!>'"� (���* !�����!+ ��> ������$*��+ >����$=#��(��+
��>|$* #�(��$��" *�!=$�!�! ($ (��!� #$��"'��!Q �J!(�#! $% ��(�*�!(
��"�'>�+ �'( �*� �$( ��#�(�> ($+ �((*�"(��� $* >�%��!��� ��(�*�"(�$�!
��(<��� ���#��!+ =���(�#�"*$�� ��(�*�"(�$�!+ ��!�"( ��(�*�"(�$�! <�(�
=���(! $* #�"*$��!+ ��> ��('*�� =*$>'"(! "��#�!(*JQ��� !'""�!!%'� �=�
=��"��( <��� �� ��!�> �( ;�� $* �� $�� $% (�� %$��$<��� $*���� >�=�*(�
#��(!� ��#�!(*J j ��#�"�� ;�$�$�J+ �$��"'��* ;�$�$�J j {���(�"!+
��'*$��$�$�J j ;�����$*+ $* ����( ��(�$�$�JQ ��� %�"'�(J <��� ^$��
$'* �"(���+ ��(�*�"(��� ��� "$##'��(J+ <��"� ��*��>J !=��! !���*��
$*���� >�=�*(#��(! ��> ;��Q ��� ��� %�"'�(J "�� �""�!! #'�(�=��
���$#�"! ��> ��%� !"���"�! %�"���(��! $� "�#='! ��> �*� ��"$'*���> ($
%$*# "$����$*�(�$�! �"*$!! (�� "�#='!Q ���"���� <��� �� �==*$=*��(�
($ (�� %�"'�(J #�#��*�! �_=�*(�!� ��> �$#� >�=�*(#��(Q�==��"�(�$�
#�(�*���! !�$'�> �� !��( >�*�"(�J ($� ��*���� �$�%��*+ ��� ���*"�
$##�((��+ ��=�*(#��( $% �$��"'��* ;�$�$�J j {���(�"!+ �Z� ;�$�
(�"��$�$�J ;�>�Q+ $*���� ����*!�(J+ �(��"�+ �� �����XZ[��Q ��`'�*��!
�J �#��� !�$'�> �� !��( ($ &*�����������"Q
!��������� ����������� ��=�*(#��( $% ;�$�$��"�� ��> ����*$�#��(�� �������*��� �! !��?�
��� "��>�>�(�! %$* � (��'*��(*�"? =$!�(�$� �� ��$�$��"�� �������*���
=*�%�*���J �( (�� �!!�!(��( =*$%�!!$* �����Q��� �==$��(�� <��� �!(����!�
� *�!��*"� =*$�*�# �� �� �#�*���� �*�� $% ��$�$��"�� �������*��� <�(�
���$��$(�"��$�$�J �==��"�(�$�!Q T�!��*"� "$'�> ��"�'>� #$��"'��*
*�"$���(�$� ��> !��!���+ ���$!"��� ����J!�! $% ��$#$��"'��!+ #�(��$��"
�������*���+��$#�#�(�"!+��$#�(�*���!+$* ��$!J!(�#���!�> ���"(*$��"!Q
�==��"�(�$�! $% *�!��*"� "�� �� %$* ��$�$��"��+��$#�>�"��+����*$�#��(��+
��*�"'�('*��+$* %$$> !J!(�#!Q��� !'""�!!%'� "��>�>�(� <��� "$#=��#��(
$��$��� >�=�*(#��(�� =*$�*�#! �� ��$�$��"�� �������*��� �"(���(��!+
=�*(�"'��*�J �( (�� #$��"'��* �����+ �( (�� $*���� ���$��$(�"��$��
$�J ��(�*Q ��"'*��� �_(�*��� %'�>��� ($ !'==$*( *�!��*"� =*$�*�#
�! �_=�"(�>Q�J=�"�� (��"���� *�!=$�!�����(��! <��� ��
(<$ "$'*!�!+ ��"�'>��� $�� $% (�� "$*� >�=�*(#���
(�� "$'*!�!+ ��> (�� >����$=#��( $% �� '==�* �����
'�>�*�*�>'�(� $* �*�>'�(� "$'*!� (��( *���"(! (��
"��>�>�(��! �*��! $% �_=�*(�!�Q���($*��� ��> �>��!���
$% '�>�*�*�>'�(� ��> �*�>'�(� !('>��(! �! �_=�"(�>Q
�'���L"�(�$�!� � ��� �� �� �==*$=*��(� >�!"�=����
<�(� >�#$�!(*�(�> �_=�*(�!� $% ��(��*�(�$� $% ���
�����*��� ��> ��$�$��"�� !"���"�!Q �==��"��(! !�$'�>
!'�#�( � ��((�* $% �==��"�(�$�+ ���������� ���+ (*��!"*�=(!+ ��>
��#�! $% (�*�� *�%�*��"�! \��"�'>��� (���=�$�� �'#��*! ��>
�#��� �>>*�!!�!] ($� ��"���� �Q���(�*+ ��=�*(#��( $% ;�$�$���
"�� j ����*$�#��(�� �������*���+ ��� T���J�T$�� ����+ $*����
����*!�(J+ �(��"�+ �� �����X�[��Q
"�����������$*���� ����*!�(J ����(�! �==��"�(�$�! %$* (�*�� ^'��$* %�"'�(J =$!�(�$�!
�� ��'*$!"���"� (��( '!��
\�] ���$#�"|����(�"+ >����$=#��(��+ #$��"'��*+ "$#='(�(�$���+
��>|$* ��$=�J!�"�� �==*$�"��! ($ (�� !('>J $% �_"�(���� "���! $* (�!!'�!
\"$�(�"( ����> ��� �( �&������������" %$* #$*� ��%$*#�(�$�]�
\Z] "��� ��>|$* >����$=#��(�� �==*$�"��! ($ !('>J (�� %'�"(�$���
$*����}�(�$� $% (�� ��*�$'! !J!(�#� %$* (��! =$!�(�$�+<� �!=�"����J !��?
��>���>'��! <�(� �_=�*(�!� �� #'*��� #$>�� !J!(�#! (��( <��� "$�(*��'(�
($ � '����*!�(J�<�>� ��(�*>�!"�=����*J #$'!� =*$�*�# \"$�(�"( �$�J
;*�(!"��* �( 3 �����������" %$* #$*� ��%$*#�(�$�]� ��>
\�] ��(��*�(��� �==*$�"��! ($ �� %'�"(�$� <�(� ��(�*�!(! (��( "$'�>
��"�'>�+ �'( �*� �$( ��#�(�> ($+ (�� $*����}�(�$� $% !��!$*J $* #$($*
!J!(�#!� !$"��� ������$*+ !$"��� "$##'��"�(�$�+ !$"��� "$���(�$�� �#$�
(�$� $* ��J $(��* �!=�"( $% "$���(�$� !'"� �! ���*���� ��> #�#$*J �(
(�� ��(<$*? �����+ !=�(��� ������(�$�+ $* >�"�!�$��#�?���� � ��*��(J $%
"'**��( *�"$*>��� $* �#����� (�"���`'�! <$'�> �� <��"$#� \"$�(�"(
;�*��*� �����J �( �������������" %$* #$*� ��%$*#�(�$�]Q
��� =$!�(�$�! �*� ��������� �� (�� >�=�*(#��(! $% ;�$#�>�"�� �"���"�!+
�$��"'��* ;�$�$�J j {���(�"!+$* �!J"�$�$�JQ��'*$!"���"� %�"'�(J <���
���� �""�!! ($ #'�(�=�� ���$#�" ��> ��%� !"���"� %�"���(��! $� "�#='!
��> �*� ��"$'*���> ($ %$*# "$����$*�(�$�! (�*$'��$'( (�� "�#='!Q
�==��"��(! !�$'�> !��> � "$��* ��((�* ($� ��'*$!"���"� ���*"�+ ���
=�*(#��( $% ��'*$��$�$�J ��> ;�����$*+ �����J {Q �'>> ����+ $*����
����*!�(J+ �(��"�+ �� �����XZ[�ZQ
#���$ %�������#���$ &���������$�� !����� Q �==��"�(�$�! �*� !$'��( %$* (�� =$!��
(�$� $% �!!�!(��( $* �!!$"��(� =*$%�!!$* %*$# "��>�>�(�! <�$!� *�!��*"�
%$"'!�! $� (�� #$��"'��* ����(�" ����J!�! $% =���( >����$=#��(�� =*$�
"�!!�!+ =*�%�*���J %*$# �� ��$�'(�$��*J =�*!=�"(���Q��� !'""�!!%'� "���
>�>�(� <��� �� ��!�> �� (�� ��=�*(#��( $% ����( ;�$�$�J ��> �! �_=�"(�>
($ "$�(*��'(� ($ (��"���� �� (�� �*�� $% =���( >����$=#��(�� ��$�$�JQ
#���$ '(��$�� �� !��$�� )�$����$�����==��"�(�$�! �*� !$'��( %$* � (��'*��(*�"? %�"'�(J =$!�(�$� \�!!�!(��(
$* �!!$"��(� �����] %*$# "��>�>�(�! <�$!� *�!��*"� %$"'!�! $� =���(�
$*����!#�� ��(�*�"(�$�! $* *�!=$�!�!|!�������� *���(�> ($ ���$(�" !(*�!!Q
��*!=�"(���! �#=�$J��� ��('*�� ��*��(�$�+���$#�"!+#�(��$�$#�"!+��>|
$* =*$(�$#�"! �*� =*�%�**�>Q��� !'""�!!%'� "��>�>�(� <��� �� ��!�> �(
(�� ;$J"� ��$#=!$� ��!(�('(�+ �� ��>�=��>��( �$(�%$*�=*$L( ��!(�('(�
�$"�(�> $� (�� $*���� ����*!�(J "�#='!Q�==��"��(! !�$'�> !'�#�( �
���������� ��� ��> (�*���=��� !(�(�#��( $% *�!��*"� ��(�*�!(! ($ ��*��
�Q��**�!$�+��"'�(J ���*"� $##�((��+;$J"���$#=!$� ��!(�('(�+ �(��"�+
�� �����Q T����< $% �==��"�(�$�! <��� ����� �$��#��* �+ Z���Q
#���$ !����*����$������ �����T� ��(�* %$* ����(��;�!�> *$= {��$#�"! $� (��
$*���� ����*!�(J "�#='! �! !$��"�(��� �==��"�(�$�! %$* � %�"'�(J�
�`'������( !"���(�!( '!��� ��$��%$*#�(�" �==*$�"��! %$* =���( *�!��*"�Q
��� !'""�!!%'� "��>�>�(� <��� >����$= ��$��%$*#�(�" ($$�! ($ ��(��*�(�
��> #��� ���$#�"!+ =*$(�$#�"!+ ��> #�(��$��(� >�(� *���(�> ($ =���(
�'(*�(�$��� `'���(J ��> ���$(�" !(*�!! ($��*��"�Q�==��"��(! #'!( ����
� "�(�}��!��= ��> � ��� �� �� �==*$=*��(� >�!"�=����Q ����*J *����
�! ��+[�Z ($ �Z+��� =�* ���'#Q �$ $�(��� �==��"�(�$� ��%$*#��
(�$�+ ��!�( (�� ��� <�� !�(� �( �773���***�&��%�"%����9�����$� %�;���<��7&Q �==��"��(!
�*� ��!$ ��"$'*���> ($ "$�(�"( ��# {�$����$��
\$$��������������"] %$* #$*� ��%$*#�(�$�Q �=�
=��"�(�$�! �� *�!=$�!� ($ (��! �> #'!( ��"�'>� (��
��"��"J ���$'�"�#��( �'#��* �T���T������
����Q���! =$!�(�$� <��� *�#��� $=�� '�(�� L���>Q
�� � ����� �� � ���� ��������� �� � ����� ����� �������� ������
FACULTY POSITIONS AVAILABLE
Presidential Biological Scholar Program
The Carver College of Medicine and the College of Liberal Arts and Sciences at the University of Iowa are seeking new investigators of outstandingpromise in the basic biological and clinical sciences.Up to four young investigators will be named as Presidential Biological Scholars at the rank ofassistant professor in the tenure-track. The award will provide signifi cant fi nancial research support for a period of four years. Funding for salary and appropriate research space will be provided by a departmental appointment. Scholars may applydirectly to the Presidential Biological ScholarProgram or be nominated by Department Heads of the Carver College of Medicine’s basic andclinical academic departments, or by Department Chairs of units in the College of Liberal Arts and Sciences at the University of Iowa.
Candidates must have a Ph.D., or equivalent, and a demonstrated record of excellence in scholarshipas evidenced by publications in leading journals in appropriate disciplines.
Applications, including a cover letter indicating the faculty position of interest, curriculum vitae, list of references, and a summary of researchaccomplishments and future plans, can be sent to:
Presidential Biological Scholar ProgramRichard Smith, M.D., Chair
Attn: Sonya HousholderOffi ce of the Dean, 200 CMAB
The University of IowaCarver College of Medicine
Iowa City, IA 52242-1101
A list of eligible departments is available at: http://www.uiowa.edu/~pbschol
The University of Iowa is an Equal Opportunity and Affi rmative Action Employer. Women and
minorities are strongly encouraged to apply.
The Ohio State UniversityExecutive Dean, Colleges of the Arts and SciencesThe Ohio State University invites nominations and applications for the positionof Executive Dean of the Colleges of the Arts and Sciences.
Five colleges constitute the Colleges of the Arts and Sciences: Arts,Biological Sciences, Humanities, Mathematical and Physical Sciences, andSocial and Behavioral Sciences. The colleges are home to 41 departmentsand schools with over 1000 faculty. The colleges provide 60 percent of allcredit hours taught at the University, including 90 percent of the GeneralEducation Curriculum and 75 percent of all honors credit hours. They offer71 undergraduate major programs that attract more than 40 percent of theUniversity’s undergraduate students. The colleges are linked by a collectivemission and share a common commitment to basic research and creativeperformance and are united by their responsibility for the University’sGeneral Education Curriculum (GEC).
The Executive Dean of the Arts and Sciences, who reports to theExecutive Vice President and Provost, provides leadership to the fivecolleges. The position offers the opportunity to plan the direction andlead the development of world-class programs and initiatives in thearts and sciences in the 21st century; to work collaboratively with thedeans of the five arts and sciences colleges in coordinating commonprograms and services; and to facilitate synergies across the collegesand with other units at the University in research, teaching, and out-reach and engagement. The Executive Dean functions with delegatedauthority from the Provost. Responsibilities include overseeing the appoint-ment, reappointment and annual evaluations of the college deans, in con-sultation with the provost; developing college budget recommendations;allocating common funds; and providing administrative oversight of under-graduate student academic services, the honors and scholars programs inthe arts and sciences, The Ohio State University Press, interdisciplinary pro-grams in the arts and sciences, development activities, and communica-tions.
The Executive Dean also provides leadership to the University and serves onthe Coordinating Council, which provides advice to the Provost on major aca-demic matters; the Council of Deans Steering Committee, which develops theagenda for the Council of Deans; and the University Senate Fiscal Committee,which reviews fiscal policies and budgets.
Qualifications and expectations for the successful candidate include:
•a record of scholarly and teaching achievement appropriate for a senior faculty appointment in one of the disciplines in the Colleges of the Arts and Sciences;
•demonstrated excellence in the leadership and management of large, complex academic programs;
•the ability to serve as an effective advocate and energetic spokesperson for the arts and sciences within the university and externally to students, alumni, donors and funding agencies;
•a history of collaborative working relationships and promoting interdisciplinary partnership;
•a demonstrated commitment to diversity; and
•a record of successful fundraising.
The Executive Dean is appointed to a five-year renewable term, subject toannual reviews by the Provost and a satisfactory formal performance reviewprior to the end of each term.
The position is available January 1, 2005, or later. Salary and otherconsiderations will be consistent with the University’s commitment to recruitthe best-qualified individual. To assure full consideration, applications andnominations should be received by October 1, 2004. The Search Committeewill begin screening dossiers on that date and will continue to receiveapplications until the Dean is selected. Applications should include astatement of interest and a curriculum vitae. Applications and nominationsshould be addressed to:
Patrick Osmer, ChairSearch Committee for the Executive Dean186 University Hall230 North Oval MallColumbus, OH 43210To build a diverse workforce, Ohio Stateencourages applications from individuals withdisabilities, minorities, veterans, and women.EEO/AA employer.
www.rii.comMerck is an equal opportunity employer—proudly
embracing diversity in all of its manifestations.©2004 Merck & Co., Inc. All rights reserved.
Novel medicines thatmake a difference.
These are the end products of innovation, drive and a desire to improve the quality of human life. If the same basic principles and values guide your career, and if you would like to make a difference, we’d liketo hear from you. We are Rosetta Inpharmatics, a wholly-owned subsidiary of Merck and Co., Inc. We conductleading-edge genomic research and data analysis focused on how medical compounds affect biology, enabling moreaccurate selection of drug targets and more efficient drug development.
We currently offer over 20 exciting career opportunities in the following departments:
Cancer Biology/Gene Modification conducts laboratory experiments directed at developing pioneering applications ofRNA interference and DNA microarray technology.
• Senior Research Biologists
• Biologists, RNA Interference Technology
Informatics researches, develops, integrates and applies cutting-edge methods, databases and software solutions toempower drug discovery and development.
• Senior Project Manager, Bioinformatics
• Senior Research Scientist positions in Custom Analysis, Data Analysis for Gene ExpressionTechnology, Pathway Analysis, and Pathway Bioinformatics
• Software Engineering positions in Database Development and Integration, Application Design,and Tool Development and Integration
Preclinical Molecular Profiling designs and conducts experiments directed at understanding mechanisms of adversedrug responses (toxicity and aberrant drug metabolism) using advanced DNA microarray technology.
• Senior Investigator/Scientific Director
Research Genetics develops and applies methods to analyze and mine genetic and molecular profiling data in segre-gating mouse and human populations to elucidate complex human diseases and identify and validate novel targetsfor those diseases.
• Senior Statistical Geneticists
For more information about our company and our career opportunities, please visit our Web site: www.rii.com. To apply foror inquire about any of our open positions, e-mail us at: [email protected].
SECTION CHIEFThe House Ear Institute has an open-ing for an experienced Scientist todevelop and direct a researchprogram on the molecular pathogen-esis of NF2 (vestibular schwannoma).The House Ear Clinic is a major centerfor vestibular schwannoma surgeryand the House Ear Institute maintainsthe largest NF2 tumor bank in theworld. HEI offers a highly competitivesalary and an attractive startup pack-age.House Ear Institute is affiliated withthe University of Southern California.Its scientists have adjunct facultyappointments with USC.Qualified scientists who are interestedin this position should submit a com-plete curriculum vitae along with adescription of past accomplishmentsin NF or Schwann cell research to:
David J. Lim, M.D., EVP, ResearchHouse Ear Institute
2100West 3rd Street, 5th FloorLos Angeles, CA 90057
Fax: 213-483-5675or e-mail to [email protected]
Additional information on HEI can befound at www.hei.org. EOE.
FACULTY POSITION IN PHYSICS
The Department of Physics anticipates one or moretenure track faculty positions at the level of Assistantor Associate Professor. One line will be in biophysics.Applicants with expertise in condensed matter physics(including Bose-Einstein condensates or laserphysics) are desired for the second position.Candidates should have a Ph.D. degree and post-doctoral experience, a strong record of originalresearch and the ability to establish active,independent, extramurally funded researchprograms. They must also demonstrate ability andcommitment to teaching physics at both theundergraduate and graduate level. Applicants should submit a CV, a list of publicationsand a research plan and should arrange for threeletters of reference to be sent as soon as possible to:Faculty Search Committee, Department ofPhysics, Room J419, The City College of New
York, Convent Avenuea n d 1 3 8 t h S t r e e t , New York, NY 10031.Consideration of appli-cations will begin onOctober 15, 2004, andcontinue until the positionsare filled.
Additional information available atwww.ccny.cuny.edu/positions/.
The City College/CUNY is an EEO/AA/IRCA/ADA Employer.
THE CITY COLLEGEThe City University
of New York
Applications and nominations are solicited for an outstanding leadership opportunity asProfessor and Chair of the Department of Cariology, Restorative Sciences, and Endodontics.This will be a full-time, tenured position to lead the largest of six academic departments inthe School of Dentistry that comprises the fields of cariology, restorative sciences, andendodontics. The position offers opportunities to further develop interdisciplinary programsat an institution committed to the highest quality of education, excellence in basic, appliedand clinical research and service to the public. The department plays an integral role in thedelivery of comprehensive patient care, practice management and dental education at thepredoctoral and graduate levels. Current research themes are clinical research and cell andmolecular biology, and include funded programs in cariology, patient centered research,biomaterials, tooth regeneration, pulp biology and dental public health.
Qualifications include a DDS, PhD, or equivalent doctoral degree and administrativecredentials. The successful candidate will have an international reputation as a scholarwith outstanding and innovative research accomplishments and an understanding of keyaspects of dental education.
Nominations and applications, including curriculum vitae should be submitted to:
David H. Kohn, Ph.D., Chair, CRSE Search Committeec/o Office of the DeanSchool of Dentistry1011 North University AvenueUniversity of Michigan, Ann Arbor, MI 48109-1078Telephone: (734)763-3310
Review of applications will begin no later than November 30, 2004
The University of Michigan is an equal opportunity/affirmative action employer.
The University of Michigan
SCHOOL OF DENTISTRY
Chair Position Department of Cariology,
Restorative Sciences, and Endodontics
Postdoctoral Fellowships
The UNC Lineberger Comprehensive Cancer Center of the University of North Carolina at Chapel Hill will have openings in 2004–2005 in its training program, now in its 29th year, for persons com-pleting graduate studies to train with excellent investigators in basic research in tumor virology, molecular carcinogenesis, molecular therapeutics, cancer cell biology, genetics, tumor immunology and research that interfaces with clinical and physical sciences. Special programs are organized for Fellows including career opportunities in academia and biotechnology.
Training is available in DNA repair, replication and mutagenesis; regulation; regulation of cel-lular proliferation and differentiation including growth factors, signal transduction pathways and intercellular communication; molecular immunology; tumor virology and pathogenesis; molecular genetics and epidemiology of cancer; and human disease models and gene therapy. Unique training resources and core facilities are supported by the NCI-designated UNC Lineberger Comprehensive Cancer Center.
Preceptors are: Shawn Ahmed, Steven Bachenheimer, Albert Baldwin, Victoria Bautch, James Bear, Keith Burridge, Sharon Campbell, Stephen Chaney, David Clemmons, Edward Collins,Marila Cordeiro-Stone, Blossom Damania, Channing Der, Robert Duronio, Shelton Earp, Beverly Errede, Rosann Farber, Jeffrey Frelinger, Frank French, Jack Griffi th, Eng-Shang Huang, Clyde Hutchison III, Kenneth Jacobson, Rudolph Juliano, David Kaufman, William Kaufmann, Shannon Kenney, Ryszard Kole, David Lee, Jason Lieb, Terry Magnuson, Patricia Maness, William Marzluff, Beverly Mitchell, Andrew Morris, Joseph Pagano, Leslie Parise, Mark Peifer, Charles Perou, TomPetes, Nancy Raab-Traub, James Raleigh, Dale Ramsden, Matthew Redinbo, R. Jude Samulski, Aziz Sancar, Michael Schaller, Jeff Sekelsky, Norman Sharpless, Oliver Smithies, John Sondek, Brian Strahl, Ronald Swanstrom, James Swenberg, Lishan Su, Holden Thorp, David Threadgill, Jenny Ting, Michael Topal, Terry Van Dyke, Kevin Weeks, Bernard Weissman, Elizabeth Wilson, Yue Xiong and Yi Zhang.
Candidates must be U.S. citizens or permanent residents. For an informational brochure or to apply (include curriculum vitae, three letters of recommendation, a statement of research interests and graduate school records) write to: Joseph S. Pagano, M.D., CB# 7295, UNC Lineberger Com-prehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7295; http://cancer.med.unc.edu.
UNC’s Comprehensive Cancer Center is an Affi rmative Action/Equal Opportunity Employer. Minority applicants are encouraged voluntarily to identify themselves.
An Assistant Member position is available in the Neurobiology and Brain Tumor Program (NBTP) at St. Jude Children’sResearch Hospital (SJCRH). The NBTP is a Cancer Center Program that integrates research groups focused on finding cures
for brain tumors. The NBTP has three subdivisions led by Tom Curran (Basic Research), Larry Kun (Clinical Research) and AmarGajjar (Translational Research). Faculty from several departments studying the basic science and clinical management of brain tumors
participate in a collaborative, interdisciplinary research environment. The new Assistant Member would be appointed in an AcademicDepartment appropriate to the applicant's field of research. We are specifically seeking investigators whose research will enhance the translation
of basic research findings into the design of new clinical trials for brain tumors. Areas of research interest include, but are not restricted to, themolecular genetic analysis of human glial tumors and the use of animal models to advance understanding and treatment of glial tumors. Applicants
should have received their doctoral degree within the past five years and achieved recognition through high profile publications.
SJCRH is the only National Cancer Institute-funded Cancer Center devoted to pediatric cancers. The Hospital operates an active in-house Phase I/II clinicaltrials program in addition to participating in both the US Pediatric Brain Tumor Consortium and the Children’s Oncology Group. SJCRH offers a very competitive
package for incoming junior faculty. This includes: salaries for the investigator and their personnel; new laboratory space; as well as startup and continuing supportfor equipment and consumables. In addition, appointees have access to a range of state-of-the-art institutional core facilities for protein and nucleic acid chemistry,
microarray analysis, cell sorting, gene knockout and transgenic technologies and imaging capabilities.
NBTP faculty members with laboratory-based programs focused on brain tumors include:
Tom Curran Molecular basis of neurodevelopment and medulloblastomaSuzanne Baker Normal and neoplastic growth in brainMichael Dyer Retinal development and retinoblastomaRichard Gilbertson Molecular basis of pediatric brain tumorsPeter McKinnon Genotoxic stress in the nervous systemMartine Roussel Cell cycle regulation and brain tumors Charles J. Sherr Cell cycle regulation and brain tumors
Candidates interested in the position should arrange to have their CV, a brief research proposal and three letters ofrecommendation sent to: Developmental Neurobiology Search Committee, Mail Stop 322, Ms. Wilma Blankenship, St. Jude Children’s Research Hospital, 332 N. Lauderdale St., Memphis, TN 38105-2794.
SJCRH is an equal opportunity employment/affirmative action employer.
Faculty Position in Brain Tumor Research
An Assistant Member position is available in the Department of Developmental Neurobiology at St.Jude Children’s Research Hospital (SJCRH). We are specifically seeking applicants with research programs
that utilize high-resolution optical imaging in living cells to investigate contemporary issues in neurobiology. Areasof research interest include, but are not restricted to, intracellular macromolecule interactions and trafficking, synapse
or receptor dynamics, cell migration and axonal guidance in the nervous system. It is anticipated that successful applicantswill have received their doctoral degrees within the past five years and have already achieved recognition through high profile
publications.
SJCRH offers a very competitive package for incoming junior faculty. This includes: salaries for the investigator and their personnel; newlaboratory space; as well as startup and continuing support for equipment and consumables. In addition, appointees have access to a range
of institutional core facilities for protein and nucleic acid chemistry, microarray analysis, gene knockout and transgenic technologies andimaging capabilities that include a state-of-the-art multiphoton microscope. The Department is already well equipped for most aspects of anatomy
and histology, cell and molecular biology, transgenics, behavioral analysis and electrophysiology.
There are presently seven faculty members in Developmental Neurobiology with the following research interests:
Tom Curran (Chair) — Molecular basis of neurodevelopmentJim Morgan (Co-Chair) — Neuronal death and regenerationRichard Smeyne — Models of neurodegenerative diseaseSuzanne Baker — Normal and neoplastic growth in brainJian Zuo — Genetics of hearing and visionMichael Dyer — Retinal development and retinoblastomaRichard Gilbertson — Molecular basis of pediatric brain tumors
Those interested in joining this multidisciplinary department should arrange to have their CV, a briefresearch proposal and three letters of recommendation sent to the Developmental NeurobiologySearch Committee, Mail Stop 323, Attention: Ms. Carol Jacks, St. Jude Children’s Research Hospital,332 N. Lauderdale St., Memphis, TN 38105-2794.
SJCRH is an affirmative action/equal opportunity employer
Faculty Position inDevelopmental Neurobiology
R. Gaurth Hansen Assistant Professorship in Biochemistry
Department of Chemistry and BiochemistryUtah State University
Applications are invited for the position of R. Gaurth Hansen Assistant Professor in Biochemistry in the Department of Chemistry and Biochem-istry at Utah State University. Qualifi ed applicants will have a Ph.D. and postdoctoral experience in biochemistry or a related area. The successful applicant is expected to develop a competitive research program in some area of biochemistry, with preference given to areas that complementexisting strengths in the department. This position is one of two that were created in honor of the late Dr. R. Gaurth Hansen, former Provost and Academic Vice President at Utah State University and are supported by Dr. William J. Rutter, co-founder and former Chairman of the Board of Chiron Corporation.
The Department of Chemistry and Biochemistry (http://www.chem.usu.edu) offers Ph.D. and M.S. degrees in Chemistry and in Biochemistry and several degrees at the undergraduate level. The Depart-ment has a strong record of attracting extramural support. The recentcompletion of the new Widtsoe building brings the total departmental spaceto 124,000 square feet. Utah State University is a land-grant institution with an enrollment of approximately 20,000 undergraduate students and 4,000 graduate students and is located in Cache Valley, 90 miles north of Salt Lake City, in the Wasatch Range of the Rocky Mountains (http://www.usu.edu).
The Search Committee will begin screening applications on October 31, 2004. Applicants for the position should send a complete curriculum vitae,and the names, mailing addresses, phone numbers, and email addresses offi ve references to: R. Gaurth Hansen Search Committee, Department of Chemistry and Biochemistry, Utah State University, 0300 Old MainHill, Logan, UT 84322. Further information about the position can be found at http://www.usu.edu/hr and http://www.chem.usu.edu.
Utah State University is an Equal Opportunity/Affi rmative Action Employer.
Harvard UniversityTheoretical and Computational Biology
Faculty Positions
The Faculty of Arts and Sciences at Harvard University is building a broad, interdisciplinary community in theoretical and computationalbiology. Up to four faculty positions are open in this area. Successful applicants will be expected to establish a vigorous research program complementing existing activities in the Departments of Molecularand Cellular Biology, Organismic and Evolutionary Biology, Statistics, Mathematics, Physics, Chemistry and Chemical Biology, the Division ofEngineering and Applied Sciences, and the Bauer Center for Genomics Research. With the opportunity for synergistic appointments, we encour-age applicants to suggest other exceptional candidates including present or potential collaborators. Applications from, or nominations of, women
and minority candidates are especially encouraged.
We cannot guarantee that applications received after November 30, 2004, will be given full consideration. Please send a cover letter, cur-riculum vitae, a statement of research plans, and names and addresses of three references to:
Computational and Theoretical Biology Search Committee
Harvard University c/o Christine Sprovieri
7 Divinity Avenue, Fairchild 113 Cambridge, MA 02138
Harvard is an Affi rmative Action/Equal Opportunity Employer.
�������������������������������������
�������������������������������� �����
�������������������������������������������������������������
��� ������ �� ������ ��� ����������� ������ ��� � �������������� � ������ ���������� �� �� ������ ����� � ���� �� �������� � � � ����� � ������ � ���� ���� �� ��� ������ ���� �� ���� ���� ��� ������������ ���� ���� �� �� ����� �� �������� ��������������� ��� ���������� ��� ��� ��� ����� � ��� ���� �� ��������� ������� ��� �� ������� ����� ���� � ��� ������ ���� ������������ ��� ������� ������ �� ��� � � ����� � ������ ��� �������� � ����� ��� ��� ���� ������ ���� � ��� � ���������� ������ ���� ������ ���� �� �������� ���� �� ��� �������� ������ � � ���������� � ��� ��������� ��� ������ � � ��� ��������� � ������������� ���� �� ��� �� �� ���������� �������� ���������� � ������������ �� �� ������� ���� ��� ���� ��� ���������� � ����� ������������� � ��������� ��������� �� � ���� �� �� ������� ������ ����������� �� �� ����� ��� ���� �� �������� � ������ � ������ ����� ������ �� �� ���� ������ ������� � ������� ��� �����������!� ��� �� ������� ���������� �� ��� ���� � ��������� ������������ ������������ ������ ��� �� ��� � ������� ��� ������������ ���� ������� �� ���� �� ����� ��� ����� ���� ���������� ���� ��� ��������� ���� �� �������� � ����������� �� ��� ������������� �� �� �������� � ��� �������� ��������� ���� ����� ���� ���������� ������ ��� � �������� � ������� ��� ��� �� �� ��������� ��� ������� � ���� �� ��� � ����� ������ � ������������ ��� �>?��� ������� ��� UV������ ���� ��� ���� � ��������� �������� ������ � ��� ����������� ���������V � ���������� ������ ���������� ������� ������ ����+,-,��,,+��� ��� ����>?"��� ����� ������ ��� ��� ���������� �������� � ��������������� � ������������� �� � �� �������� �� "����� ��� ���� � ��� ���� ���� �� ���������
��� ��������� � � ������ �� � ��� � �������������� ��� ����������� ��� ���� ������� � ������� �� ��������� � ���� � � ������ ��� ��� � ������� �� ������ �� ������������
www.jax.org
The Jackson Laboratory, an independent, mammalian genetics research institution,and an NCI-designated Basic Cancer Center has just launched a major researchexpansion. New faculty will be recruited in the following areas:
• Neurobiology • Cancer Biology• Reproductive/Developmental Biology• Immunology/Hematology • Metabolic Disease Research• Computational Biology/Bioinformatics
We are recruiting scientists at all levels who hold a Ph.D., M.D. or D.V.M., have arecord of research excellence and have the ability to develop a competitive,independent research program, taking full advantage of the mouse as a research tool.
The Jackson Laboratory offers a unique scientific research opportunity, includingexcellent collaborative opportunities with our staff of 35 Principal Investigators,unparalleled mouse and genetic resources, outstanding scientific support services,highly successful Postdoctoral and Predoctoral training programs, and a major meet-ing center, featuring courses and conferences centered around the mouse as a modelfor human development and disease. For more information, please visit our Web site(www.jax.org).
Applicants for faculty positions should send a curriculum vitae, statement of research interests, and the names of at least three references to: Director’s Office,The Jackson Laboratory,600 Main St., Bar Harbor, Maine 04609, or email: [email protected] (preferred method of application).
The Jackson Laboratory is an EEO/AA Employer
FACULTY RECRUITING
FACULTY OF SCIENCESchool of Biotechnology and Biomolecular Sciences
Professors/Associate Professorsand Senior Lecturers/Lecturers The School is seeking to make five full-time continuingacademic appointments, at both senior and junior levels,across a broad spectrum of areas in Biotechnology andBiomolecular Sciences. These are designed to develop newframeworks and approaches to researching molecular cellbiology and biotechnology whilst simultaneously building thecapacity to exploit this research within the context of basic,biomedical, environmental and industrial applications.
The appointments will be in two broad areas:
People from EEO groups including suitably qualified womenare encouraged to apply. The University reserves the right tofill the positions by invitation or not to fill all of the positions.
Enquiries to Professor Peter Little, Head of School, on telephone(61 2) 9385 2032; facsimile (61 2) 9385 1483, or email:[email protected]
For an information package, email: [email protected], or telephone: (61 2) 9385 2730; facsimile: (61 2) 9662 2832.
Applications close 20 October 2004.
APPLIEDBIOTECHNOLOGY/
APPLIED CELL CULTURE
MOLECULAR CELL BIOLOGY/
SYSTEMS BIOLOGY
For full details of these positions see: http://www.hr.unsw.edu.au/employment/newjobaca.htm
U32813R
The Department of Biochemistryand Molecular Biology at the Uni-versity of Chicago invites applicationsand nominations for several tenure-trackfaculty positions. We seek candidates with outstanding programs and/or promise forengaging fundamental problems and basic molecular mechanisms at the interface ofthe biological and physical sciences andwho will value teaching in the departmental program. We are linked to sister programs inphysical sciences, bioinformatics and com-putation, cell biology, basic medical science,the Institute for Biophysical Dynamics and the Argonne National Laboratory. (See http://bmb.bsd.uchicago.edu/)
Applications should include a completecurriculum vitae, a list of publications, asummary of past accomplishments and aplan for future research. Applicants should also arrange for three letters of reference.Please submit applications or nominations by December 1, 2004 to: Faculty Search Committee, Department of Biochemistry and Molecular Biology, Mailbox #5, 920 East 58th Street, Chicago, IL 60637.
The University of Chicago is an Affi rma-tive Action/Equal Opportunity Employer.
The Biophysics Research Division at the Uni-versity of Michigan invites applications for twoopen positions in Biophysics. Positions will be at a rank appropriate to the candidate’s quali-fi cations and may be at the rank of Assistant,Associate, or Full Professor. Applications in allareas of Biophysics are encouraged, including both molecular and cellular biophysics and boththeoretical and experimental methods. Prefer-ence will be given to applicants that complementexisting strengths in structural biology, spectros-copy, molecular dynamics, and single-moleculestudies. Successful applicants will be appointedin the Research Professor track in Biophysics and will receive a tenure-track teaching appoint-ment in the appropriate department (Chemistry, Physics, Biology, or Biological Chemistry).
All candidates should send a curriculum vitae together with a brief description of their researchplans and a statement of their teaching interests, a summary of funding history (senior candidatesonly) and should arrange to have three letters of recommendation (junior candidates only)submitted to: Professor James Penner-Hahn, Biophysics Research Division, University of Michigan, 930 N. University Avenue, AnnArbor, MI 48109-1055. The positions willremain open until fi lled but preference willbe given to applicants who have submitted all requested materials prior to November 1, 2004.Electronic applications are preferred (send [email protected]).
The University of Michigan is supportive of the needs of dual career couples and is a non-discriminatory, Affi rmative Action Employer.
JOINT FACULTY POSITIONCourant Institute of Mathematical Sciences & Department of Biology
CENTER FOR COMPARATIVE FUNCTIONAL GENOMICS
As part of a new interdisciplinary initiative at NYU, applicants are invited to apply for a faculty
position (rank open) joint between the Courant Institute of Mathematical Sciences and the
Department of Biology/Center for Comparative Functional Genomics to begin September 1, 2005, or
as negotiated, subject to budgetary and administrative approval. Candidates working at the interface
of Biology (genomics, regulatory networks, cell biology) and Scientific Computation
(bioinformatics, simulation, data analysis and cellular modeling) are strongly encouraged to apply.
Candidates will be expected to have or to develop active, externally funded research programs, and
to participate in teaching activities at both the undergraduate and graduate levels.
The Courant Institute is a leading center in pure and applied mathematics and in computer science,
with research strengths of relevance to this initiative in ordinary and partial differential equations,
numerical analysis, machine learning, computational biology, and probability theory. The Biology
Department is undergoing rapid growth in Genomics Faculty and with its Center for Functional
Comparative Genomics offers an outstanding and dynamic research environment with a strong
emphasis on the integration of genomics, developmental genetics and evolution.
An application letter with research statement, curriculum vitae, and three letters of reference should
be sent to: Chair of the Search Committee, Dr. Leslie Greengard, Courant Institute, New York
University, 251 Mercer Street, NY, NY 10012. Selection of initial candidates will begin December1, 2004, and proceed on a rolling basis thereafter.
NYU is an Equal Opportunity/Affirmative Action Employer.
American Association for the Advancement of ScienceAmerican Association of Colleges of Pharmacy American Academy of Neurology American Chemical Society American Dental Association American Geological Institute American Geophysical Union American Meteorological Society American Nuclear Society American Physical Society American Psychological Association American Society for Microbiology American Society of Agronomy American Society of Civil Engineers
American Society of Mechanical Engineers American Veterinary Medical Association American Welding Society Crop Science Society of America Federation of Animal Science Societies Geological Society of America Institute of Electrical and Electronics Engineers – USA Institute of Food Technologists Institute of Navigation Materials Research Society Optical Society of America Society for Research in Child Development Soil Science Society of America SPIE-The International Society for Optical Engineering
2005-06 Congressional Science and EngineeringFellowship Program®
PROGRAM: Scientists and engineers spend one year as special assistants on the staffs of Members ofCongress or congressional committees, working in legislative areas requiring scientific and technicalexpertise. The program includes an orientation on congressional and executive branch operations, and ayear-long seminar program on issues involving science and public policy. Fellows receive stipends fromtheir sponsoring societies.
PURPOSE: To provide a unique public policy learning experience, to demonstrate the value of science-government interaction and to make practical contributions to the more effective use of scientific andtechnical knowledge in government.
CRITERIA: A prospective Fellow must be a postdoctoral to mid-career scientist or engineer; demon-strate exceptional competence in some area of science or engineering; be cognizant of and demonstratesensitivity toward political and social issues; and perhaps most importantly, have a strong interest andsome experience in applying personal knowledge toward the solution of societal problems.
SPONSORS: Approximately 30 national professional scientific and engineering societies will sponsor orcosponsor Congressional Fellows in 2005-06. Applicants should apply directly to the appropriate profes-sional society. Applicants may apply to more than one society. Stipends, application procedures, timetablesand deadlines vary by society. Persons from underrepresented minority groups and persons with disabilitiesare encouraged to apply.
For more details about the program and a list of the participating societies contact:
American Association for the Advancement of Science
Congressional Science and Engineering Fellowship Program
1200 New York Avenue, NW • Washington, DC 20005
Phone: 202.326.6700 • E-mail: [email protected]
www.fellowships.aaas.org
THE UNIVERSITY OF SOUTH DAKOTA
VICE PRESIDENT FOR RESEARCHThe Vice President for Research (VPR) will serve as the chief research officer for TheUniversity of South Dakota (USD), a doctoral/research intensive university with col-leges or schools of arts and sciences, medicine, business, law, education, and fine arts.The university is a multi-campus institution, with the main campus in Vermillion, off-campus work at a variety of locations around the state, and medical school campusesin Vermillion (basic sciences) and Sioux Falls (main clinical site). The university iscommitted to strengthening its competitive research, technology-transfer, and studentresearch involvement. Within the state of South Dakota and at the university, researchhas taken on an unprecedented level of priority, due in part to the Governor’s 2010Initiative, which has research as one of five major state goals. South Dakota is anEPSCoR/IdEA state and plays a national leadership role in those programs.The VPR will oversee all matters related to research and creative scholarship at theuniversity, including sponsored projects administration (preaward), internalresearch incentive programming, development of research-related policy and budg-eting, federal and state relations, undergraduate and graduate student research pro-gramming, intellectual property and technology transfer, and research compliance.The VPR reports to the Vice President for Academic Affairs, and is a member ofboth the President’s Executive Committee and the Academic Affairs WorkingGroup. As such the VPR interacts regularly with campus leadership at all levels.The VPR also represents the university on the Research Affairs Council of theBoard of Regents, along with the other chief research officers of the system and anewly created system vice president for research. The VPR serves as the principalcontact with federal funding agencies and other sources of research funding.The VPR is a full-time position with a competitive salary based upon experienceand potential for taking the university to a new level of research leadership and per-formance. The successful candidate will be a dynamic leader with intimate knowl-edge of research from the perspective of a successful, competitively fundedresearcher as well as a research administrator. An earned doctorate is necessary,preferably a Ph.D., along with a portfolio that demonstrates knowledge of research,leadership skills, creativity, and a high level of productivity.Send letter of application, resume, names and contact information for three refer-ences to: VPR Search Committee, ATTN: Emery Wasley, Human Resources.University of South Dakota. 414 East Clark Street, Vermillion, SD 57069.To receive full consideration, submit resumes before September 30, 2004. Searchwill continue until the position is filled.The University of South Dakota is an Equal Opportunity/AffirmativeAction Employer committed to increasing the diversity of its facul-ty, staff and students.
M. D. Anderson Cancer Center is an EOE employer and does not discriminate on the basis of race, color, national origin, gender, sexual orientation, age, religion, disability or
veteran status, except where such distinction is required by law. All positions atM. D. Anderson are considered security sensitive; drug screening and thoroughbackground checks will be conducted. The University of Texas M. D. Anderson
Cancer Center values diversity in its broadest sense. Diversity works at M. D. Anderson. Smoke-free environment.
ASSISTANT PROFESSORDepartment of Cancer Biology
The Department of Cancer Biology at The Universityof Texas M. D. Anderson Cancer Center is seekingapplicants for a tenure track faculty research position atthe Assistant Professor level.
Qualified candidates should have a Ph.D. or M.D.degree and must be self-motivated, independentscientists capable of establishing competitive research programs with a focus on cancer biology and the tumor microenvironment. Postgraduate training in the generalfield of cancer biology, cell biology and/or vascularbiology is essential.
Salary is competitive, with an excellent compensationand benefits package.
Interested applicants should send a letter and curriculumvitae to the search committee chair: Alan. J. Schroit,Ph.D., Department of Cancer Biology, 1515 HolcombeBlvd., Box 173, Houston, Texas 77030.
Tenure-Track Faculty PositionThe Department of Microbiology and Immunology
Medical University of South CarolinaCharleston, South Carolina
The Department of Microbiology and Immunology at the Medical Universityof South Carolina is seeking applicants for a tenure-track position at the Assistant/Associate level in the areas of microbiology, including biodefense,vaccinology, and microbial or viral pathogenesis of infectious disease or cancer. New faculty will have access to competitive salary and startup funds and benefi t from protected time for the establishment of a nationally competi-tive research program. Appointment requires independent funding.
The Department provides teaching to multiple colleges within the University,and all faculty participate in professional and graduate education as well as maintain an active research program. Laboratories are about to undergo major infrastructural renovations and a number of new faculty will be hired in the near future. The Medical University of South Carolina is a rapidly growing research environment. Extramural research support has consistentlyincreased over the past 10 years, topping $156 million last fi scal year. Major research centers include the Hollings Cancer Center, Gazes Cardiovascular Research Institute, Neuroscience Institute, Children’s Research Institute,Center for Aging and the Center for advanced Imaging Research. State-of-the-art research facilities include X-ray crystallography, mass spectrometry, proteomics, microarrays, functional imaging, and confocal microscopy. A BSL-3 small animal/wet lab has been funded and plans are underway for its construction. A major new facility in biomolecular NMR is under development. The Charleston area provides an outstanding quality of life in a historic coastal community offering excellent opportunities in the arts, sports, recreation, and cuisine.
Please send curriculum vitae, state of research interests, and three letters of recommendation addressing both research and teaching potential to:Microbiology Search Committee, c/o James S. Norris, Ph.D., Depart-ment of Microbiology and Immunology, Medical University of South Carolina, 173 Ashley Avenue, PIO Box 250504, Charleston, SC 29425; http://www2.musc.edu/MIC/Micro4803/index.html.
The Medical University of South Carolina is an Affi rmative Action/Equal Opportunity Employer.
ASSOCIATE PROVOST FOR RESEARCHRush University
As a major component of Rush University MedicalCenter, the largest private academic medical center inIllinois, Rush University integrates patient care, edu-cation, and research through the practitioner-teachermodel. More than 1,500 research projects�includinghundreds of clinical studies to test the effectivenessand safety of new therapies and medical devices�areunder way at Rush. Annual research funding hasgrown from $20 million in 1990 to nearly $70 milliontoday. Some of this important work is housed in thenew Robert H. and Terri Cohn Research Building, astate-of-the-art facility where Rush investigators areconducting genetic research to identify the causes of awide range of diseases.
The Associate Provost for Research will be expectedto provide leadership for advancing the research goalsof the University and will oversee a major expansion inthe base of research funding from federal and stateagencies, foundations, and the private sector. The in-cumbent will have a major role in setting the directionfor research in the medical college and other healthprofessional schools; the position entails both aca-demic and management responsibilities.
Candidate qualifications include an M.D., Ph.D.,M.D./Ph.D., or other appropriate terminal degree,with a commitment to achieving excellence in re-search; a strong background in a research-intensivediscipline with a clear understanding of the challengesand opportunities facing research faculty; and a distin-guished academic background. Also desirable are arecord of scholarly achievement, a record of adminis-trative effectiveness, and an acknowledged reputationin research administration.
Please send nominations or applications to: EugeneBauer, M.D. at e-mail: [email protected], ormail to: Korn/Ferry International, 1800 CenturyPark East, Suite 900, Los Angeles, CA 90067.
Rush University is an Affirmative Action/Equal Opportu-nity Employer.
St. John Fisher College in Rochester, New York,invites applications for a full-time, tenure-track AS-SISTANT PROFESSOR position in biology. Weseek a candidate with a strong commitment to teach-ing and undergraduate research. The successful can-didate’s primary responsibilities will include introduc-tory biology, anatomy/physiology, and upper-levelcourse(s) in an area of interest. Earned Doctorate withexperience in molecular biology required; postdoc-toral training preferred.
Applicants should submit curriculum vitae, state-ment of teaching philosophy, research interests, pastteaching experience, and a list of references to:Dr. Mel Wentland, Biology Department, St. JohnFisher College, 3690 East Avenue, Rochester, NY14618. Fax: 585-385-7311; e-mail: [email protected]. Applications must be received by November16, 2004, at which time the review will begin andcontinue until the position is filled.
To learn more about Fisher, please visit our web-site: http://www.sjfc.edu. Equal Opportunity Employ-er/Affirmative Action.
MOLECULAR AND CELLULARNEUROSCIENCE RESEARCH
POSTDOCTORAL RESEARCH ASSOCI-ATE sought to join multidisciplinary molecular andcellular neuroscience group in studies of native orrecombinant nicotinic acetylcholine receptors andsubunit genetics. Investigations encompass moleculargenetic, protein chemical, electrophysiological, im-munological, and pharmacological approaches in aunique and dynamic institution. Send curriculum vi-tae, names and addresses of three references, and briefstatement of research experience, interests, and careerobjectives to: R. J. Lukas, Ph.D., Division of Neu-robiology, Barrow Neurological Institute, St. Jo-seph’s Hospital and Medical Center, 350 WestThomas Road, Phoenix, AZ 85013. E-mail:[email protected]. Affirmative Action/Equal OpportunityEmployer.
TENURE-TRACK ASSISTANT PROFESSORIN POPULATION ECOLOGY
The Department of Zoology, University of BritishColumbia (UBC), seeks applications for a tenure-track position in population ecology. We encourageindividuals who conduct field research on animal pop-ulations, preferably terrestrial vertebrates or intertidalanimals, to apply. Duties include developing a strongresearch program, teaching courses in ecology or or-ganismal biology and actively participating in theUBC Biodiversity Research Centre.
Salary will be commensurate with experience. Ap-pointment will be at the Assistant Professor level andis subject to final budgetary approval.
Applicants should send curriculum vitae, summaryof research interests and teaching philosophy, andreprints of three key publications. Letters should besent directly from three referees. Address all materialsto: Dr. Bill Milsom, Head, Department of Zoolo-gy, University of British Columbia, 6270 Univer-sity Boulevard, Vancouver, BC, Canada, V6T 1Z4(e-mail: [email protected], fax: 604-822-5780). Applications accepted up to 20 September2004, or until a suitable candidate is found.
The University of British Columbia hires on the basis ofmerit and is committed to employment equity. All qualifiedapplicants are encouraged to apply; however, in accordance withCanadian immigration requirements, Canadian citizens andpermanent residents of Canada will be given priority.
POSTDOCTORAL POSITION available imme-diately to understand the mechanism and dynamics ofadenosine triphosphate-driven DNA packaging inviruses using bacteriophage T4 model. Novel combi-natorial mutagenesis, biochemical, and structural ap-proaches will be used. Strong background in proteinbiochemistry desired. Send curriculum vitae andnames of three references to: Dr. Venigalla Rao,Department of Biology, Catholic University, 620Michigan Avenue, N.E., Washington, DC 20064.E-mail: [email protected].
POSITIONS OPEN POSITIONS OPEN POSITIONS OPEN
17 SEPTEMBER 2004 VOL 305 SCIENCE Science Careers www.sciencecareers.org1836
ASSISTANT PROFESSOR OF BIOCHEMISTRYSPECIALIZING IN NMR SPECTROSCOPY
The DEPARTMENT OF BIOCHEMISTRY at the UNIVERSITY OF TEXAS HEALTH SCIENCE CENTER AT SAN ANTONIO invites applications for a tenure-track Assistant Professor position in the area of NUCLEAR MAGNETIC RESONANCE (NMR) studies of biologicalmacromolecules. Applicants are expected to have expertise in developing and/or applying techniques in NMR spectroscopy to gain insights intomacromolecular structure, function, and dynamics. The successfulcandidate will join a faculty with strong research programs in NMR, X-ray crystallography, and other biophysical approaches to structure/function analysis of proteins (see http://biochem.uthscsa.edu) and is part of theexpansion of the Department that will occur over the course of the next 3 – 4 years under the new leadership of Dr. Bruce Nicholson. Access will be provided to the state-of-the-art NMR equipment recently installed and operated by the Department including Bruker AV 500, 600, and 700 MHz NMR spectrometers and a high sensitivity cryogenically cooled probe for the 600 MHz spectrometer (see http://nmr.uthscsa.edu).
San Antonio offers a rich multicultural environment, excellent educational and recreational opportunities, a temperate climate, and a very reasonable costof living. A generous start-up package will be provided, along with access to a large array of other shared facilities/centers operated by the Department, including those for X-ray crystallography, analytical ultracentrifugation,mass spectrometry, surface plasmon resonance, and others. Candidates will be expected to develop a vigorous, externally funded research program and contribute to teaching in the graduate, medical, or dental curricula. Applicants should send by October 31, 2004 a curriculum vitae, a 1-3 page summary of past and proposed research, and three letters of reference to: Dr. Andrew P Hinck, Chair of the Search Committee, Department of Biochemistry, MC7760, Allied Health Building Room 5.206, U. Texas Health Sci. Ctr. at SanAntonio, 7703 Floyd Curl Dr., San Antonio, TX 78229-3900. Questions should be addressed to [email protected]. All faculty appointments are designated as security sensitive positions.
The University of Texas Health Science Center at San Antonio is an Equal Employment Opportunity/Affi rmative Action Employer.
������� �������� ��������
����������������������������������!"#���$%��$&'���#*�+
�+�/+$3�"#���'�4&'$+��$*!�/�#��"��$#5�6'�8$'��#;�4*"�&��<"��$���
��� ����� � �������� ����������� ��� ������ ��!������ "�#����� � ��� %���'��� ��� ���� *���� !� *��'���+� �������� ������ ��� 7+������ �� ��� ���� �������� �������� � ����� 8��� �+��� �''������� !� � '����� � �������� '���������< =''������� >�� �� ���� �� ��� ��+�� �! =������� � =������� ?������ @�Q�+����� �� ��� ��[ �! =������� � =������� ��!����\< *�������� �� �]'����� �� ��+���' ����������^ ���+��+� ������ '����� ���� ��� ����� ������^ ���'��������^ ������^ ��� ��������� �''������ �� ������ ��� ���� ������ �! '�������� ��� ���'��] ����#'�������� �����������'�<
��� %���'��� ��� ���� *���� � � ���������+� ��+������ >�� �]���� �������� � �������� ���������� �������� 7+������^ _�������� ������� ��� ������ ���+����< �� �!!� ��+�����^ ��� ������'�� !������ !� "`= ��Q������^ "`= ������� ��� ���'�������� ������< ?���#�' '��[��� ��� ����� � ���'���+�< ����� �+�> �! �''������� >�� ���� ��������� ��� ������� ���� �''�'��� �������� � ����{��<
_� !������ ����������^ '����� �''�� �� |��< }~^ ����< =''������ ������ ����� � ������� +���^ ��������� �! ������ ������� ��� ��� �! {+� �!������ �� ?��'��� �< 8����[^ � ������� �< ?���^ ��� ��� `���^ ����� � �������� ����������� ��� ������ ��!������ "������^ %���'��� ��� ���� *���� ���� �������� �������� � ��� ?����^ ����� 8���^ �= ����}<
������������!�"��#"$%�&'�*�"#+8��;"#!���*��!$8�%=!�?J*!K#�L�Q!�K���;8
Department of Health and Human ServicesNational Institutes of Health
The National Cancer Institute Center for Cancer Research
In collaboration with The National Heart, Lung, and Blood Institute, The National Institute of Allergy and Infectious Diseases, and The National Institute of Diabetes and Digestive and Kidney Diseases has formedgraduate education partnerships with North Carolina State University, Michigan State University, The University of Illinois, and The University of Maryland to offer combined comparative pathology and biomedical research training for doctors of veterinary medicine designed to addresstranslation of research fi ndings from animal models to the clinical setting. Following initial pathology and graduate training at a university partner, trainees transfer for additional training within the intramural research labo-ratories of the NCI, NHLBI, NIAID, or NIDDK. The training initiative provides for multidisciplinary training in animal pathophysiology, rodent or NHP pathology, human pathology, molecular biology, and medicalresearch. The program leads to a Ph.D. and eligibility for certifi cation as a veterinary pathologist. Support includes attractive stipend, tuitionand health insurance benefi ts, and other training assistance. The CCR website http://ccr.nci.nih.gov/resources/training/default.asp offers detailed descriptions of the programs and other links to important infor-mation. Candidate veterinarians must be U.S. citizens or U.S. permanent residents, and have less than fi ve years postdoctoral experience.
Apply on-line for fellowships beginning July 1, 2005, with up to 5 years sup-port, through the NIH Graduate Partnership Program at http://gpp.nih.gov/.On-line applications are due by December 2, 2004. For consideration, separate application must also be made directly to partnership university graduate schools of choice. For additional information contact either Dr. Jonathan S. Wiest at [email protected] or Dr. R. Mark Simpson, at [email protected].
DHHS and NIH are Equal Opportunity Employers.
FACULTY POSITIONSBiological Sciences
The Department of Biological Sciences at the University of Pittsburgh invites applications for two full-time tenure-track faculty appointments,pending budgetary approval. Appointments are anticipated to begin in September 2005. Our department has a broad-based, interactive group of researchers whose interests encompass nearly every area of modern biology. We are seeking colleagues from any discipline; those withinterests in gene expression, chromatin structure/function, genomics, host-pathogen interactions, cell or developmental biology, bioinformat-ics, biochemistry or biophysics are especially encouraged to apply. Theseappointments are expected to be made at the ASSISTANT PROFES-SOR level, but experienced candidates with outstanding records will be considered for appointment at higher ranks. The successful candi-dates must have a Ph.D. and extensive postdoctoral experience andwill be expected to establish extramurally funded research programs, train graduate students, and participate in undergraduate education. To ensure full consideration, applications should be received by November 1, 2004. Applicants should send curriculum vitae along with a summaryof research interests and goals as a single electronic document (PDF format preferred) to [email protected]. In addition, applicants should arrange to have at least three letters of reference sent to:
Search CommitteeDepartment of Biological Sciences
University of PittsburghPittsburgh, PA 15260
(412) 624-4266
Further information on the Department of Biological Sciences isavailable at: http://www.pitt.edu/~biology.
The University of Pittsburgh is an Affi rmative Action/Equal Opportunity Employer. Women and members of minority groups
underrepresented in academia are especially encouraged to apply.
Biomedical Tenure-Track Position-Assistant Professor
The Department of Biology at the University of Dayton, OH, USA,seeks applicants for a tenure-track Assistant Professor position, begin-ning August 2005. Requirements include a Ph.D., relevant post-doctoral experience, and a commitment to excellence in research and teaching. We seek an individual with primary research interest in mammalian physiol-ogy, cell biology, tissue regeneration, bionanotechnology or stem cell biology. The successful candidate is expected to develop an extramural funded research program that will complement existing faculty in the above areas, and to involve Ph.D., M.S. and undergraduate students in his/her research program. Teaching expectations will be one lecture courseper semester in mammalian physiology or cell biology, and supervision of the laboratory component. Start-up funds are available to establish a new research laboratory in the candidate’s area of expertise.
To apply, send curriculum vitae, statements of research direction and teaching interests, selected reprints, and at least three letters of recommen-dation to: Dr. Marie-Claude Hofmann, Chair of the Search Commit-tee, Department of Biology, University of Dayton, 300 College Park, Dayton, OH 45469-2320, USA. The committee will begin reviewing the applications by October 25, 2004, and the search will continue until the position is fi lled.
The University of Dayton is a private comprehensive universitylocated in the Columbus-Dayton-Cincinnati (Ohio) metroplex area.Please visit our web sites: http://biology.udayton.edu or http://artssciences.udayton.edu/Biology/ for further information.
The University of Dayton, a comprehensive Catholic University founded by the Society of Mary in 1850, is an Equal Opportunity/Affi rmative Action Employer. Women, minorities, individuals with disabilities and veterans are strongly encouraged to apply. The
University of Dayton is fi rmly committed to the principle of diversity.
UNIVERSITY of
invites applications for a tenure-track position at theASSISTANT/ASSOCIATE PROFESSOR level.
We seek highly interactive candidates with an interest in teachingand an outstanding record of research achievement in any area ofgenetics including, but not limited to, human genetics or genomicsand pathophysiology of genetic disease.
Candidates should have a Ph.D. and/or M.D. degree andpostdoctoral research experience. The new faculty member isexpected to participate in the teaching of graduate and medicalstudents, and to establish an independent research program thatstrengthens the diverse research interests of the currentdepartmental faculty members (http://genetics.stanford.edu).
Stanford University is an equal opportunity, affirmative actionemployer. Candidates are encouraged to apply electronically byOctober 31, 2004 with curriculum vitae, a statement of theirresearch interests, teaching experience and future research plans,and the names, phone numbers, email and postal addresses of threeor more individuals willing to serve as references, to:
Uta Francke M.D.Professor of Genetics and Pediatrics
Stanford University School of MedicineBeckman Center for Molecular and Genetic Medicine B203
Stanford, CA 94305-5323
email: [email protected]
S TAN F O R D U N I V E R I S T YSCHOOL OF MEDICINE
department of
PEGGY M. PENNINGTON COLEENDOWED CHAIR
in Maternal Biology and the Risk of ObesityThe Pennington Biomedical Research Center is an
internationally recognized nutritional research center.Its 70-member faculty apply multidisciplinary ap-proaches to understanding the interactions betweennutrition, health, and chronic disease primarily as itrelates to obesity, diabetes, cardiovascular disease,cancer, and aging. As a research center, its teachingand training is limited to mentoring of graduate stu-dents and postdoctoral fellows. The Center has madesignificant investments in a range of cutting-edgetechnologies including metabolic chambers, metabol-ic kitchen facilities, mass spectrometry laboratories,confocal microscopy suite, genomics, proteomics, mi-croarrays, and transgenics and has both inpatient andoutpatient facilities for clinical studies. The main re-search facility has about 400,000 square feet of re-search space. Further information on current facultyand their research may be found at website: http://www.pbrc.edu. All faculty appointments are aca-demic appointments within the Louisiana State Uni-versity System.
The Pennington Biomedical Research Center in-vites qualified applicants to apply for a FULL PRO-FESSOR POSITION to be appointed to the PeggyM. Pennington Cole Endowed Chair in Maternal Bi-ology and the Risk of Obesity. The chair holder isanticipated to have an M.D., Ph.D., or equivalentqualifications but would be expected to use basic sci-ence approaches to understand mechanisms underly-ing the fetal and maternal effects on health of theoffspring and on subsequent risks of adulthood dis-eases. The chair holder will have an international rep-utation as an accomplished researcher, a well-fundedresearch program, a strong publication record, andleadership abilities. The chair holder will have dem-onstrated ability to work well with other scientists incollaborative research. The overarching aim will be tostudy the mechanisms through which nutritional andenvironmental influences during pregnancy, lacta-tion, and the neonatal period influence the risk fordevelopment of obesity and its co-morbidities duringadult life. Identification of markers that can subse-quently be used in human populations to identify riskstatus of human infants is a likely outcome of thisresearch.
Applications, including cover letter, curriculum vi-tae, bibliography, names, addresses, and telephonenumbers of three references will be accepted until theposition is filled. Send to: Claude Bouchard, Ph.D.,Executive Director, Pennington Biomedical Re-search Center, 6400 Perkins Road, Baton Rouge,LA 70808. Telephone: 225-763-2513; fax: 225-763-0935. Louisiana State University System/PenningtonBiomedical Research Center is an Equal Opportunity/Affirma-tive Action Employer.
FACULTY POSITIONBiological Mechanism
MIT, Department of BiologyMIT is seeking an outstanding scientist with a
strong record of research accomplishment for atenure-track position. Applicants at all faculty levelswill be considered. A successful applicant will be ex-pected to have or develop a significant and indepen-dent research program and have a commitment toexcellence in undergraduate and graduate education.
Applicants should submit curriculum vitae, includ-ing a summary of current and proposed research pro-grams, and should arrange for three letters of recom-mendation to be sent to:
Biological Mechanism Search CommitteeAttn: Tania Baker
MIT 77 Massachusetts AvenueRoom 68-523
Cambridge, MA 02139Consideration of completed applications will begin
on November 15, 2004.MIT is an Affirmative Action/Equal Opportunity Employ-
er. Qualified women and minority candidates are especiallyencouraged to apply.
TENURE-TRACK FACULTYPOSITIONS
Department of Cellular andIntegrative Physiology
Indiana University School of Medicine
The Department seeks applicants for threetenure-track positions. Academic rank will becommensurate with experience. Applicantsmust have an M.D. or Ph.D. degree, at leastthree years of postdoctoral experience, high-quality peer-reviewed publications, evidenceof independent research, and competitivefunding potential. We seek innovative scien-tists using integrated molecular, cellular, andwhole animal approaches to study importantphysiological questions. All areas of researchwill be considered, but preference will be givento candidates who complement strengths inthe Department in smooth muscle, cytoskele-ton, mechanotransduction, growth, apoptosis,renal physiology, membranes (ion channels,caveolae, adhesion junctions), diabetes, imag-ing, and computational biology. Successful ap-plicants will be expected to maintain an extra-murally funded research program and partici-pate in the teaching of medical and graduatestudents. Significant resources available in-clude competitive startup packages, doublingof newly renovated laboratory space, and long-term research and salary incentives. This is thefirst phase of growth in the Department whichis expected to include six-to-eight new posi-tions in the next four-to-five years. Furtherinformation can be found at website: http://www.iupui.edu/��medphys. Review of appli-cations will begin immediately and the dead-line for receipt is October 12, 2004.
Applicants should send (preferably in elec-tronic format) their curriculum vitae, briefstatement of research interests and goals, andthe names of three references to: Dr. MichaelSturek, Chair, Department of Cellular andIntegrative Physiology, c/o Marlene Brown(e-mail: [email protected]), 635 Barn-hill Drive, M.S. 309, Indianapolis, IN46202-5120. Indiana University is an Equal Em-ployment Opportunity/Affirmative Action Employer.
STAFF AND POSTDOCTORAL POSITIONSLNLS/ABTLuS�BRAZIL
The Brazilian Synchrotron Light Laboratory(LNLS) is expanding its scientific and technical staff.The following qualified people are invited to apply forboth visiting and staff positions:
Researchers (code RSCR-SYN) with postdoctoralexperience in synchrotron X-ray scattering and/or ab-sorption spectroscopy, vacuum ultraviolet spectrosco-py, or surface science. Scientists and engineers inter-ested in the development of insertion devices, syn-chrotron light instrumentation, microfabrication, andlight sources. Postdoctoral candidates (code PDOC-SYN) with previous experience in synchrotron lightresearch as well as outstanding candidates without thisexperience but willing to work in the areas above.
Researchers (code RSCR-BIO) with postdoctoralexperience in the area of biophysics including proteinand peptide nuclear magnetic resonance, structure-driven drug design, protein chemistry, folding, mod-eling, crystallography, and molecular biology, andPostdoctoral candidates (code PDOC-BIO) in theareas above.
The LNLS offers an intellectually stimulating scien-tific environment and state-of-the-art facilities. Suc-cessful candidates will be expected to show an out-standing research record in science and/or technology.
Application deadline is November 30, 2004. Pleaserefer to the code when applying.
Send resume, list of publications, and the names ofthree references to: Director General, LNLS/ABTLuS, C.P. 6192, 13084-971 Campinas (SP),Brazil or e-mail: [email protected]. Website:http://www.lnls.br.
Department of Chemistry. DePauw University.Biochemistry or bio-organic chemistry. Applicationsinvited for TENURE-TRACK POSITION begin-ning August 2005. Ph.D. preferred, all but disserta-tion required. Commitment to teaching and researchwith undergraduates required. Prior teaching or post-doctoral experience desired. Successful candidate willteach biochemistry and organic chemistry in Depart-ment’s introductory core and advanced courses inspecialty area, and will be encouraged to developcourse for non-majors. Commitment to develop vig-orous research program involving undergraduate bio-chemistry majors required. DePauw has exceptionalprograms for supporting its faculty members, includ-ing a pre-tenure leave and funding for professionaland curriculum development activities (see website:http://www.depauw.edu/admin/acadaffairs/facdev.htm). Matching funds and other incentiveswill be provided to support search for external fund-ing. Submit letter of application, curriculum vitae,three letters of recommendation, graduate and under-graduate transcripts, statements of teaching and re-search interests and teaching philosophy, and evi-dence of teaching effectiveness to: Professor BryanHanson, Search Chair, Department of Chemistry,DePauw University, Greencastle, IN 46135. Ma-terials may be submitted electronically to e-mail:[email protected]. Review of applications beginsOctober 1, 2004, and continues until position isfilled. DePauw University is an Affirmative Action/EqualOpportunity Employer. Women and members of underrepre-sented groups are encouraged to apply.
ASSISTANT PROFESSORSystems Visual Neuroscience
The University of California at Berkeley invites ap-plications for a tenure-track position in the School ofOptometry at the Assistant Professor level beginningin the fall of 2005, with a joint appointment in theHelen Wills Neuroscience Institute (50 percent Op-tometry and 50 percent HWNI). Applicants shouldhold a doctoral degree in cognitive neuroscience,neuroscience, psychology, vision science, or a relatedfield. We are particularly interested in candidates em-ploying single unit neurophysiology or imaging (ei-ther optical imaging or functional magnetic resonanceimaging) to study the neural mechanisms of vision.Applications must be postmarked by November 15,2004, and should include a resume, selected publica-tions, a brief statement of research interests and futureplans. Send applications to: Chair, Faculty SearchCommittee, Systems Visual Neuroscience, Schoolof Optometry, University of California, Berkeley,CA 94720-2020. Candidates should also arrangeto have at least three letters of recommendation sentto the above address, and request that referencesread the University’s statement on confidentiali-ty (website: http://apo.chance.berkeley.edu/evalltr.html) prior to submitting their letters. Ap-plications postmarked after November 15, 2004,cannot be considered. The University of California is anEqual Opportunity/Affirmative Action Employer. All qual-ified applicants including minorities and women are encour-aged to apply.
The Center of Marine Biotechnology of the Uni-versity of Maryland Biotechnology Institute invitesapplications for a tenure-track ASSISTANT/ASSO-CIATE PROFESSOR position in fish immunology.Ph.D. with postdoctoral training in the application ofmolecular/biochemical approaches to understandinghumoral or cellular immunity preferred. Candidatesmust demonstrate strong research record, includingpublication of seminal papers on structure/functionof fish immune system. Applicants should submit let-ter of intent describing specific interest, experience,overall qualifications, future plans and career goals,with detailed curriculum vitae, including list of pub-lications, and names and addresses of at least threeprofessional references. Packages should be sent nolater than October 30, 2004, to: Search CommitteeChair, Fish Immunology, Center of Marine Bio-technology, 701 East Pratt Street, Suite 236, Bal-timore, MD 21202-3101.
POSITIONS OPEN POSITIONS OPEN POSITIONS OPEN
17 SEPTEMBER 2004 VOL 305 SCIENCE Science Careers www.sciencecareers.org1838
FACULTY POSITION IN BIOPHYSICSThe Johns Hopkins University
The Thomas C. Jenkins Department ofBiophysics seeks candidates for the firstof TWO TENURETRACK/TENUREDFACULTY POSITIONS in structural Biology/macromolecular function. We are particularly interested in candidates withexpertise in NMR and X-ray crystallography who apply these methods to the mechanism of biological regulation. Candidates shouldhave a strong background in the physical sci-ences. Faculty using NMR will participate in an expanding interdepartmental NMR center which includes faculty from Chemistryand Biology. The Biophysics Departmentanticipates significant growth during thenext several years, including a new building and additional faculty appointments. Positionsare at any rank. The fi rst position is available immediately; the successful candidate willparticipate in recruitment for the secondposition, which becomes available the fol-lowing year.
Please send by 15 December 2004 a cover letter, CV, and brief description of yourresearch plans to: Faculty Search Commit-tee, T. C. Jenkins Department of Biophys-ics, Johns Hopkins University, 3400 N.Charles St., Baltimore, MD 21218-2685;tel. 410-516-7245. Candidates should arrangefor three letters of reference to be sent to the same address.
The Johns Hopkins University is an Affi rmative Action/Equal Opportunity
Employer.
DHHS and NIH areEqual Opportunity Employers
Department of Health and Human ServicesNational Institutes of HealthNational Institute of Environmental Health SciencesResearch Triangle Park, North Carolina
COMPUTATIONAL CHEMISTLaboratory of Structural Biology
Ms. Cindy Garrard (Vacancy DIR04-08)
National Institutes of Health
National Institute of Environmental Health Sciences
P.O. Box 12233, Maildrop A2-06
Research Triangle Park, NC 27709
The Laboratory of Structural Biology (LSB) of the National Institute ofEnvironmental Health Sciences, Research Triangle Park, North Carolina, isseeking a computational chemist to serve as a staff scientist in LSB. Thesuccessful candidate will work very closely with a senior member of the LSB
and will provide computational chemistry expertise to the LSB. Applicantsshould have a Doctoral degree in physical or theoretical chemistry (orequivalent) with expertise in computational chemistry and demonstratedskills in a) computer modeling (chemistry, biochemistry), including 3D graphics,molecular mechanics and dynamics, docking, quantummechanics/chemistry),b) computer programming (Fortran and/or C essential, other languagesdesirable), c) managing computer hardware (single processor, multiprocessor,networks, printers), working knowledge of UNIX, LINUX, WINDOWS andother OS, and ability to evaluate, port and install modeling and visualizationsoftware d) helping to write scientific papers for quality journals, e)workingin group efforts as well as working largely independently towards commongoals. The level of appointment will be commensurate with the selectee'sbackground. For additional information about this position, contactDr. Thomas Darden, Head, Molecular Modeling Group, at 919-541-4933([email protected]).
Interested persons should send their curriculum vitae with a statement ofresearch interests, and arrange for three letters of recommendation to besent by November 15, 2004, to:
DEPARTMENT OF BIOCHEMISTRY
UNIVERSITY OF IOWA
ROY J. AND LUCILLE A. CARVER COLLEGE OF MEDICINEThe Dept. of Biochemistry of the Univ. of Iowa seeks highly
qualified applicants for one or more tenure track faculty positions at any rank.The department has broad interests (www.biochem.uiowa.edu) and currentfaculty have strong collaborative interactions with colleagues throughout theCarver College of Medicine and the University. They participate in multipleinterdisciplinary training programs including the Center for Biocatalysis andBioprocessing, Genetics, Molecular Biology, Molecular Parasitology and theMedical Scientist Training Program. Outstanding new and renovated researchspace with excellent shared instrumentation is available. We welcomeapplicants with research interests in any area of biochemistry includingcellular, developmental and molecular biology. All applicants must have arelevant graduate degree (Ph.D., M.D., or the equivalent) and productivepostdoctoral experience. They will be judged on their potential to initiate andmaintain a vigorous, independent research program, to teach and to trainstudents and postdoctoral fellows.
Applications should include a complete CV, a 3-page summary ofresearch accomplishments and future plans, and a brief statement of teachinginterests. These should be sent as a single pdf file [email protected], with the applicant’s last name in the filename;reprints in pdf format may be sent with the application. Applicants for therank of Assistant Professor should ask three scientists familiar with theirqualifications to submit letters of reference, preferably [email protected]. Applicants at this rank also will be consideredfor nomination to the Univ. of Iowa Presidential Biological Scholar Program(www.uiowa.edu/~pbschol). Senior candidates should provide names of 3references. Consideration of completed applications will begin on October15, 2004. Questions may be directed to Prof. Madeline A. Shea, Chair of theFaculty Search Committee, Dept. of Biochemistry, Roy J. and Lucille A.Carver College of Medicine, Univ. of Iowa, Iowa City, IA, 52242-1109,phone 319-335-7933, fax 319-335-9570. The University of Iowa is anAffirmative Action/Equal Opportunity Employer. Women and minorities arestrongly encouraged to apply.
FACULTY POSITIONS in BIOCHEMISTRY
�������� ������ ��������
�������� ������ ��� ������������� ��������
������ �� �������� ��� �����������
��W�A ����� �� �A��C�� ��� ��D�������G �A A������ � �����I JK������� A������
������C G� ��C��G G�� ��G����� X��G�C ��C ��D�C�����G�� �A��C��12�X�34
W�������GA �KAG ��D� � Y������CA ���C��51�C �����C51�� � ��A������� C���G�� G���D�C�����G�� A������ �C �������C��� M�G� �����AGC�G�� �����GI G� K���CAG��� ��K�G���A�������CI �C��C�� M�G� ��G����� ��D�C�����G�� �����I �������G���A41 ������G��� G� ��AA�AA��� ��C� �N��KG�D� JK�������G���A �� G�� �����C �N��KG�D� ��CD���5G�� ����D��K�� �KAG �����AGC�G� �����I �C��G�D� �C����� A��D��� A����A ��� �N���6G����� �����GI G� ����K����G� A������ �AAK�A51C�AK�GA51��� �����GA G� � �C��� C���� ��
�K������A ��� AG��������CA ����K���� ��W �C��C�� ������CA51�G��C ����C�� �������A5X���C�AA51��� �G��C A������ �C����Q�G���A4
��C �� �D�CD��M �� �X��A ��G�D�G��A51����A� �� G� MMM4���4��D7���C4
���A �A � �����C �N��KG�D� ��CD��� ��A�G���41 ��� ��A�G��� ����A �� �K�I18�59::� ��� ���A�A ���G����C �:519::�41 ��� A���CI C���� �A1;8:�5�9� G�1;8��5::��������� �� JK�������G���A4
W�������GA �KAG ���C�AA G�� �N��KG�D� ��� G�������� JK�������G���A ��A�C���� ��G�� D�����I ����K������G ��C G��A ��A�G���41 X��� �C MC�G� G� ����W7W�7�7��� �K��� �A�KC��A �G���12��:W35189::1����AI�D���� WD��K�51�4�451��A����6G��51�4X4119:�:41 ��K ��I ��M����� � �K�� ����K������G �G MMM4KA����A4���4��D4��� D�����I �K���C �A ��W6:�6���6�6�994
����� ���������� ��������������������� ���� �� ����� �� �! ��� ������� ���� �� ��������� ���������
��� �� �� ����� ����������! �����!���
ASSISTANT OR ASSOCIATE PROFESSOR(RESEARCH) IN SLEEP RESEARCH
Sleep Research CenterDepartment of Psychiatry and
Behavioral SciencesStanford University School of Medicine
The Department of Psychiatry and Behavioral Sci-ences at the Stanford University School of Medicine isrecruiting for the full-time Research Faculty positionin sleep research. This is a nontenure contract positionat the level of Assistant/Associate Professor (Re-search) in the School of Medicine, and is co-terminuswith funding. Applicants for this position must have aPh.D., M.D., or equivalent degree. They must berecognized by the scientific community as possessinga superior level of expertise in the neurobiology ofsleep and basic biological rhythms. A proven record ofinvestigative productivity in basic science related tothe neurobiology of sleep, electroencephalography(EEG), and its circadian timing is required. Experi-ence in fundraising and directing a multidisciplinaryresearch group/program is desirable. The selectedcandidate will direct an ongoing multidisciplinary re-search program to investigate the underpinnings ofcircadian and homeostatic elements of sleep-wakeregulation and the EEG. Expertise and interest inbasic or clinical sleep research, whether in humansand/or animal models is required. The applicant willbe expected to collaborate with other members of theSleep Research Center in the utilization of the existinglarge-scale rodent sleep research facility and partici-pate in joint projects. Candidates should demonstratean interest in and commitment to teaching includinggraduate/medical students, residents, and postdoc-toral fellows.
Applicants should forward curriculum vitae and thenames of three references within four weeks of thedate of publication of this advertisement to:
Dr. Emmanuel MignotChairman of the Search Committee
Department of Psychiatry and Behavioral SciencesStanford University School of Medicine
Sleep Research Center701 Welch Road, Suite 2226
Stanford, CA 94304Stanford University is an Equal Opportunity/Affirmative
Action Employer.
TENURE-TRACK BIOLOGY FACULTYDepartment of Biology, University of Wisconsin-
La Crosse (UW-La Crosse), invites applications fortwo, academic year, tenure-track positions at the levelof ASSISTANT PROFESSOR for fall 2005.
Plant Ecologist: Teach plant biology, a course inarea of expertise, and participate in teaching one ormore of the following: ecology, introductory biology,plant-microbe interactions.
Comparative Animal Physiologist: Teach compara-tive animal physiology or environmental physiology, acourse in area of expertise, and participate in teachingone or more of the following: human anatomy andphysiology, vertebrate zoology, and introductory bi-ology.
Ph.D. in a biological science is required. Must havea strong commitment to undergraduate education.Some previous teaching experience is desirable. Willbe expected to develop an externally funded researchprogram and direct undergraduate and graduate(M.S.) research. Positions contingent upon availabil-ity of funding. Submit letter of application, curricu-lum vitae, statements of teaching philosophy and re-search interests, graduate and undergraduate tran-scripts, and three letters of recommendation by No-vember 1, 2004, to: Dr. Mark Sandheinrich,Department of Biology, University of Wisconsin-La Crosse, La Crosse, WI 54601. Website:http://www.uwlax.edu/vacancies/.
UW-La Crosse is an Affirmative Action/Equal Opportuni-ty Employer. Women, persons of color, and individuals with adisability are encouraged to apply. “Reasonable accommoda-tions” are provided for applicants with disabilities.
ASSISTANT PROFESSOR,HOST-PATHOGEN
INTERACTIONSDepartment of Plant Pathology
Michigan State UniversityEast Lansing, Michigan
We seek to hire a tenure-system, academic-year ap-pointment faculty member at the Assistant Professorlevel who will use integrative and molecular approach-es to study important problems in host-pathogen in-teractions. The candidate is expected to establish aninternationally recognized research program on host-pathogen interactions involving any major group ofplant pathogens. Research emphasis may range fromfunctional genomics, proteomics, bioinformatics,sub-cellular imaging, molecular basis of pathogenicityand/or disease susceptibility/resistance of plant-pathogen interactions, or pathogen genetics/biolo-gy; the approach should contribute to an understand-ing of molecular events in the interactions of plantsand pathogens resulting in plant resistance or plantdisease. The successful candidate will also participatein graduate and/or undergraduate teaching.
The Department of Plant Pathology has 14 tenure-system faculty. Research facilities include modern lab-oratory and plant growth facilities. Michigan StateUniversity has a large and vibrant community of plantbiologists with research interests spanning all majorareas in the plant sciences. State-of-the-art analyticalcore facilities include the Genomics Technology Sup-port Facility, Mass Spectrometry/Proteomics Facilityand Center for Advanced Microscopy. Because of theopportunity for synergistic appointments, we encour-age applicants from candidates who are present orpotential collaborators. There is an option for a jointappointment in biochemistry and molecular biology,crop and soil sciences, forestry, horticulture, or plantbiology. Candidates must possess a Ph.D. and havegraduate and/or postdoctoral research experience inplant pathology with demonstrated productivity andevidence of potential for independent research. Theapplication should include: cover letter, curriculumvitae, statement of research interests and future direc-tions, and three or more letters of reference. Non-residents of the United States must satisfy requirements neces-sary for issuance of a U.S. work permit prior to the date ofappointment. Application materials should be addressedto:
Dr. George W. SundinDepartment of Plant Pathology
Michigan State UniversityEast Lansing, MI 48824-1311
Telephone: 517-355-4573E-mail: [email protected]
Closing date for applications is October 31, 2004,but search will continue until a suitable candidate isidentified. Michigan State University is an Affirmative Ac-tion/Equal Opportunity Employer.
A position is available for a nontenure-track ASSIS-TANT/ASSOCIATE RESEARCH PROFES-SOR within the Wells Center for Pediatric Researchat the Indiana University School of Medicine. Candi-dates must have Ph.D. or M.D. degrees, and a strongbackground in molecular and cellular biology, includ-ing experience with murine embryo development.The ideal candidate will have experience in hemato-poietic stem and progenitor cell biology and confocallaser microscopy. Expertise in the method of wholeembryo in vitro culture is also desirable. Applicantsshould send current curriculum vitae and contact in-formation for at least three professional references to:
Mervin C. Yoder, M.D.Professor of Pediatrics
and Biochemistry and Molecular BiologyHerman B. Wells Center for Pediatric Research
1044 W. WalnutBuilding R4-Room 402EIndianapolis, IN 46202
E-mail: [email protected] University is an Equal Employment Opportunity/
Affirmative Action Employer, Minorities/Females/Persons withDisabilities.
FACULTY POSITIONS IN NEW CARDIO-VASCULAR RESEARCH INSTITUTE
As part of its $500 million 10-year initiative, theUniversity of Rochester School of Medicine has pur-chased an 88,000 square foot building which willbecome home to a new Cardiovascular Research In-stitute. The Institute will build upon a well-estab-lished research base in the areas of vascular biology,ischemia-reperfusion injury, molecular pharmacolo-gy, signal transduction, and cardiovascular genetics(see website: http://www.urmc.rochester.edu/Aab/Cardio.htm). Competitive startup packages arepresently available for two developmental biologists atthe JUNIOR FACULTY level. The Institute is par-ticularly interested in outstanding candidates with de-monstrable promise in the area of zebrafish andmouse cardiovascular development. Qualified appli-cants should send curriculum vitae, research plan, andthree letters of recommendation to:
Faculty Search Committee,Cardiovascular Research Institute
Box 679University of Rochester Medical Center
601 Elmwood AvenueRochester, NY 14642Fax: 716-273-1497
University of Rochester is an Equal Opportunity Employer,committed to workforce diversity.
The Biology Department of Gonzaga Universityinvites applications for a tenure-track ASSISTANTPROFESSOR position. We seek to hire a broadlytrained biologist who will complement the existingfaculty. The position will begin fall 2005. Teachingassignments may include Diversity of Life(BIOL101), as well as upper-division courses in areaof specialization and courses for nonscience majors orK-12 educators. The area of specialization is open,but areas of particular interest to the Departmentinclude microbial ecology/evolution, entomology, oranimal physiology. To receive full consideration, ap-plications and three letters of recommendation shouldbe received by 1 November 2004. Applicationsshould consist of cover letter, curriculum vitae, state-ment of research interests and plans for undergradu-ate participation, and statement of teaching philoso-phy and interests. Applications and letters should besent to: Dr. Nancy Staub, AD Box 6, GonzagaUniversity, 502 E. Boone Avenue, Spokane, WA99258. For further information about applying forthis position and a temporary spring 2005 position,see our website: http://gonzology.gonzaga.edu/faculty-staff/jobs/. Gonzaga University is a Jesuit,Catholic, humanistic university looking for candidates who cancontribute to its educational needs and missions. Gonzaga is anAffirmative Action/Equal Opportunity Employer seeking toincrease its diversity.
MOLECULAR BIOLOGISTThe Department of Biology, College of Charleston,
invites applications for a tenure-track position in mo-lecular biology at the ASSISTANT PROFESSORlevel. Candidates must possess a Ph.D., a strong com-mitment to teaching, and an active research programwith the potential for undergraduate involvement.Teaching responsibilities include an upper-level lec-ture and laboratory course in molecular biology aswell as an upper-level course in the candidate’s area ofspecialization. Advising premedical students is alsoexpected. The College of Charleston is a public liberalarts and sciences institution of 10,000 students. TheCollege’s primary aims are teaching and research ex-cellence. In addition to its undergraduate programs,the Department offers M.S. degrees in marine biologyand environmental studies. Information about the Bi-ology Department can be found at website: http://www.cofc.edu/��biology/. Applicants should sub-mit curriculum vitae, statements of teaching philoso-phy and research interests, reprints of recent publica-tions, and three letters of reference by 1 November2004 to: Chair, Department of Biology, College ofCharleston, Charleston, SC 29424. The College ofCharleston is an Equal Opportunity/Affirmative Action Em-ployer and encourages the applications of qualified women andminorities.
POSITIONS OPEN POSITIONS OPEN POSITIONS OPEN
17 SEPTEMBER 2004 VOL 305 SCIENCE Science Careers www.sciencecareers.org1840
Department of Health and Human ServicesNational Institutes of Health
National Cancer Institute
Program Manager, Cancer Nanotechnology
The Offi ce of the Director of the National Cancer Institute (NCI), NationalInstitutes of Health (NIH), Department of Health and Human Services (DHHS) invites applications for a Program Manager, Cancer Nanotech-nology in the Offi ce of Technology and Industrial Relations. This is a key position responsible for providing leadership, management, and oversightin the fi eld of nanotechnology to lead programmatic development at NCI. NCI is seeking a visionary leader of national stature to coordinate the implementation of the NCI cancer nanotechnology plan (CNPlan).
The individual selected for this position will possess an M.D. or Ph.D. degree (or have equivalent training and experience) with independentresearch and administrative experience and a publication record in the application of nanotechnologies for biomedical purposes. In addition,individual will have experiences in materials development/synthesis/fabrication, physical/chemical properties of nanomaterials and nanode-vices, prototyping and beta-testing.
Salary is commensurate with research experience and accomplishments, and a full Civil Service package of benefi ts (including retirement, health, life and long-term care insurance, Thrift Savings Plan participation, etc.) is available.
The NCI vacancy announcement for this position contains completeapplication procedures and lists all mandatory information which youmust submit with your application. To obtain the vacancy announcement for this position which will be available on or about September 17, 2004 and posted under announcement number NCI-04-3109, you may visit the NIH Career website at: http://careerhere.nih.gov OR you can have it faxed to you by calling 1-800-728-JOBS (for local calls, 301-594-2953). Applications must be postmarked by October 29, 2004.
NCI, NIH and DHHS are Equal Opportunity Employers.
TEMPLE UNIVERSITYDEPARTMENT OF CHEMISTRY
BIOCHEMISTRY/CHEMICAL BIOLOGY FACULTY POSITION
The Department of Chemistry at Temple University invites applications and nominations for a tenured/tenure-track faculty position in the area of Biochemistry/Chemical Biology. The position is open with respect torank. Applicants at the Assistant Professor level are expected to demon-strate strong potential for establishing a vigorous research program funded by peer-reviewed research grants and for developing excellence in teaching. Applicants at the Associate and Full Professor levels are expected to have established research programs of high quality, supported by substantialexternally funded peer-reviewed research grants and demonstrated signifi cant teaching accomplishments. Salaries are highly competitive and substantial resources have been provided for startup funding. Ample modern laboratory space is available.
The Department of Chemistry (http://www.chem.temple.edu) is engaged ina new initiative of growth in research and education, and enjoys multiple col-laborative interactions with research groups in other departments in the Col-lege of Science and Technology, the College of Engineering, and the Health Sciences campus. Temple University (http://www.temple.edu), located in historic Philadelphia, is part of the Pennsylvania Commonwealth System of Higher Education, and serves over 34,000 students. Philadelphia is a vibrant center of the arts and sciences and a major locus of chemical, biomedical, pharmaceutical and biotechnological research and development.
Applicants should submit curriculum vitae; a statement of research interests and (if applicable) current grant support; a statement of teaching philosophy; and arrange to have four letters of recommendation sent to: Dr. Robert J. Levis, Professor and Chair, Department of Chemistry (016-00), Temple University, Beury Hall, 13th and Norris Streets, Philadelphia, PA 19122.Review of applications will begin immediately and will continue until suit-able candidates are identifi ed.
Temple University is an Equal Opportunity/Affi rmative Action Employer. The Department specifi cally invites and encourages applications from
women and minorities.
TEMPLE UNIVERSITYDEPARTMENT OF CHEMISTRY
ORGANIC CHEMISTRY FACULTY POSITION
The Department of Chemistry at Temple University invites applications and nominations for a tenured/tenure-track faculty position in the area of Organic Chemistry. The position is open with respect to rank. Applicants atthe Assistant Professor level are expected to demonstrate strong potential forestablishing a vigorous research program funded by peer-reviewed researchgrants and for developing excellence in teaching. Applicants at the Associate and Full Professor levels are expected to have established research programsof high quality, supported by substantial externally funded peer-reviewed research grants, and demonstrated signifi cant teaching accomplishments. Salaries are highly competitive and substantial resources have been providedfor startup funding. Ample modern laboratory space is available.
The Department of Chemistry (http://www.chem.temple.edu) is engaged ina new initiative of growth in research and education, and enjoys multiple col-laborative interactions with research groups in other departments in the Col-lege of Science and Technology, the College of Engineering, and the HealthSciences campus. Temple University (http://www.temple.edu), located in historic Philadelphia, is part of the Pennsylvania Commonwealth System ofHigher Education, and serves over 34,000 students. Philadelphia is a vibrantcenter of the arts and sciences and a major locus of chemical, biomedical, pharmaceutical and biotechnological research and development.
Applicants should submit curriculum vitae; a statement of research interestsand (if applicable) current grant support; a statement of teaching philosophy;and arrange to have four letters of recommendation sent to: Dr. Robert J. Levis, Professor and Chair, Department of Chemistry (016-00), Temple University, Beury Hall, 13th and Norris Streets, Philadelphia, PA 19122.Review of applications will begin immediately and will continue until suit-able candidates are identifi ed.
Temple University is an Equal Opportunity/Affi rmative Action Employer. The Department specifi cally invites and encourages applications from
women and minorities.
Faculty Positions in Neuroscience, Cell and Developmental Biology
Department of Cell BiologyEmory University School of Medicine
Applications are invited for tenure-track faculty positions at the ASSISTANT, ASSOCIATE and FULL PROFESSOR levels. The Department is interested in strengthening its programs in cell, developmental and neurobiology. All outstanding candidates are encouraged to apply, although particular areas of interest include:
• molecular and cellular neuroscience, and • the use of model genetic systems to study basic biomedical
problems.
Emory University is in the midst of a major growth initiative to be one of the premier research institutions in the nation. Within the past seven years, eight new investigators, including a new Chair, have joined the Department of Cell Biology, which recently relocated into the new Whitehead BiomedicalResearch Building. Virtually all other departments in the School of Medicine are experiencing similar growth, with the recruitment of new Chairs, faculty and occupancy of new physical facilities. Emory bioscience faculty participatein one or more of eight rapidly growing, interdisciplinary predoctoral train-ing programs. For questions contact: [email protected]. Interviewsbegin January 2005.
Send curriculum vitae, research plan, representative reprints and three refer-ence letters by December 1, 2004, to:
Chair, Search CommitteeDepartment of Cell Biology
Emory University School of MedicineWhitehead Research Building, Room 400
615 Michael StreetAtlanta, GA 30322
Emory University is an Equal Opportunity Employer. Women and members of underrepresented racial and ethnic groups
are encouraged to apply.
TENURED FACULTY POSITIONUniversity of California, Irvine
Department of ChemistryThe Department of Chemistry and the Program in
Pharmaceutical Sciences at the University of Califor-nia, Irvine (UCI), jointly seek applicants for a tenuredposition at the level of ASSOCIATE PROFESSORor PROFESSOR in the Department of Chemistrybeginning January 1, 2005. The successful candidatemust have a distinguished record of research achieve-ment in any area of chemistry related to pharmaceu-tical sciences, including (but not limited to) synthetic,computational, or biophysical chemistry. Excellentoral and written communication skills are essential, asare teaching experience and relevant, high-impactpublications in peer-reviewed journals. The successfulcandidate is expected to play a leading role in estab-lishing a new graduate program in pharmaceuticalsciences at UCI and will also advise on the develop-ment of an undergraduate major in this field. Accord-ingly, he or she must have, in addition to an interna-tionally recognized research program in chemistry, astrong interest in interdisciplinary research and expe-rience in pharmaceutical/medicinal chemistry or a re-lated discipline. Applicants should submit a letter ofapplication, curriculum vitae, a sample of recent sci-entific research papers, and a minimum of three refer-ences to:
Richard Chamberlin, Ph.D.Chair, Search Committee, Chemistry/
Pharmaceutical SciencesDepartment of Chemistry
University of California, IrvineIrvine, CA 92697
E-mail: [email protected] immediate consideration, applications should
be postmarked by October 15, 2004. Position willremain open until filled. Information about programscan be found at website: http://www.chem.uci.edu. The University of California is an Equal OpportunityEmployer committed to excellence through diversity.
TENURE-TRACK POSITIONIMMUNOLOGY
The Department of Microbiology and Immunolo-gy at the SUNY Upstate Medical University is recruit-ing new faculty at the rank of ASSISTANT or AS-SOCIATE PROFESSOR. Candidates should have aM.D., Ph.D., or equivalent and have sufficient expe-rience to establish an independent, funded researchprogram in molecular or cellular immunology. Com-petitive salary and startup packages are available in-cluding recently renovated laboratory and officespace. Applications should be received by November1, 2004, to receive full consideration but the searchwill continue until all positions are filled. Send curric-ulum vitae, summary of research interests, and threeletters of references to: Steven Taffet, Ph.D., Chair,Faculty Search Committee, Department of Micro-biology and Immunology, SUNY Upstate Medi-cal University, 750 E. Adams Street, Syracuse, NY13210. E-mail: [email protected].
The Upstate Medical University is an Affirmative Action/Equal Opportunity Employer.
Tenure-track ASSISTANT/ASSOCIATE PRO-FESSOR of Biology, Department of Biological Sci-ences, Hunter College, CUNY. Qualifications: Ph.Din molecular or cell biology, and a demonstrated com-mitment to research and teaching. Postdoctoral andteaching experience, publications in peer-reviewedjournals, and a record of extramural funding pre-ferred. Active, independent programs of extramurallyfunded research in genetics or cell biology are expect-ed to be established or sustained as well as teaching inone or more of these areas at the undergraduate andgraduate levels. Salaries and startup packages are com-petitive, commensurate with experience.
Send curriculum vitae, a statement of research in-terests, representative publications, and names of ref-erences to: Professor Shirley Raps, Chair SearchCommittee, Department of Biological Sciences,Hunter College, CUNY, 695 Park Avenue, NewYork, NY 10021.
TWO TENURE-TRACK FACULTYPOSITIONS IN GLYCOSCIENCE
The University of GeorgiaComplex Carbohydrate Research Center (CCRC)
is seeking candidates for two Tenure-track Facultypositions to enhance our emphasis in biomedical gly-cosciences. While we are particularly interested in can-didates with strong backgrounds in glycosaminogly-can structure/function, glyco-immunology, cell/de-velopmental, cancer, or chemical biology, we wel-come outstanding applicants from all areas ofglycobiology. Individuals who employ novel biophys-ical methods to address the biological functions ofglycoconjugates are also invited to apply. Demon-strated creativity, commitment to teaching excel-lence, and willingness to participate in a multidisci-plinary, collegial environment are essential. TheCCRC presently has 15 tenured/tenure-track facultymembers who have a common interest in the chem-istry and biology of complex carbohydrates and gly-coconjugates. The CCRC is home to five fundedCenters: two National Center for Research Resourc-es/NIH, one National Science Foundation, one De-partment of Energy, and the University of GeorgiaCancer Center. Successful candidates will occupy lab-oratory and office space in the new 140,000 squarefeet CCRC building equipped with outstanding ana-lytical, synthetic, biochemical, and cell culture/fer-mentation facilities. Applications received by Decem-ber 1, 2004, are assured of consideration. Rank, sala-ry, and startup funds will be commensurate with qual-ifications and experience. Applicants should send acover letter, curriculum vitae, a detailed description ofresearch goals, and arrange for four letters of recom-mendation to be sent to e-mail: [email protected] or to: Chair, Faculty Search Commit-tee, Complex Carbohydrate Research Center,University of Georgia, 315 Riverbend Road, Ath-ens, GA 30602-4712, U.S.A. An Affirmative Action/Equal Employment Opportunity Institution.
The Department of Biology invites applications foran anticipated tenure-track position at the rank ofASSISTANT or ASSOCIATE PROFESSOR avail-able September 2005. Qualifications include a Ph.D.in microbiology or a related discipline, substantialpostdoctoral/professional experience, and evidenceof outstanding research and academic potential. Can-didates are expected to have or to develop an inde-pendently funded research program of national cali-ber and to participate in teaching. All fields of micro-biology will be considered for this position. The suc-cessful candidate will complement the existingresearch strengths of our Department (website:http://www.biology.neu.edu) and will have an op-portunity to participate in the interdisciplinary Bio-technology Institute.
Applicants should send curriculum vitae, a state-ment of research interests and plans, and a statementof teaching experience and/or interests to: Microbi-ology Faculty Search Committee, 134 MugarHall, Northeastern University, Boston, MA02115. Please arrange to have at least three letters ofreference sent independently to the committee. Re-view of applications will begin November 15, 2004,and will continue until the position is filled. Northeast-ern is an Equal Opportunity/Affirmative Action Title IXUniversity. Women and minority candidates are especiallyencouraged to apply.
The University of Michigan, School of PublicHealth, Department of Environmental Health Sci-ences seeks applications for tenure-track ASSIS-TANT PROFESSOR positions in the areas of expo-sure assessment and environmental microbiology.Concurrent searches are underway for DEPART-MENT CHAIR and for an OPEN-RANK POSI-TION in risk science. Interested candidates shouldvisit website: http://www.sph.umich.edu/ehs.The University of Michigan is an Affirmative Action/EqualOpportunity Employer.
ASSISTANT PROFESSORVertebrate Developmental Biology
The University of Texas at Austin (UT-Austin)invites applications for a tenure-track position as anAssistant Professor in the Section of Molecular Celland Developmental Biology. We seek an outstand-ing investigator who will build an active researchprogram addressing important research questions invertebrate developmental biology. The successfulapplicant will be joining the biology community atUT-Austin during an exciting phase of growth, withrecent hires in cell biology, developmental biology,neuroscience, structural biology, and related areas.Very generous startup funds are available, and thesuccessful candidate will also be eligible for affilia-tion with the Institute for Cellular and MolecularBiology, which provides state-of-the-art facilitiesand supports an excellent graduate program.
To ensure full consideration, all application materi-als should be received by November 15, 2004. Appli-cants should send their curriculum vitae, a statementof current and future research interests, representativepublications, and three letters of reference to:
Chair, Search Committeec/o Maureen Meko
Section of Molecular Cell andDevelopmental Biology
University of Texas at Austin1 University Station A6700BIO 311, 205W 24th Street
Austin, TX 78712-0183
Websites: http://www.biosci.utexas.edu/MCDB/and http://www.icmb.utexas.edu/.
The University of Texas, Austin is an Equal OpportunityEmployer. Qualified women and minorities are encouraged toapply.
LIFE SCIENCES TEACHING POSITIONat the University of Houston
The Honors College and the Department of Biol-ogy and Biochemistry at the University of Houston(UH) invite applications for an Instructional ASSIS-TANT PROFESSOR to contribute to the teachingmission of these units. This position is a twelve-month, nontenure-track appointment, with the pos-sibility of annual renewal. The successful applicant willteach Honors sections of courses in Introductory Bi-ology and Genetics, and will coordinate special pro-grams for honors students in the natural sciences. Theposition requires an earned Doctorate in any appro-priate area of the life sciences, broad knowledge ofbiology and biochemistry, prior teaching experienceat the post-secondary level, and a commitment tohigh quality undergraduate teaching. Review of appli-cations will begin October 15, 2004. Start date: Jan-uary 2005 preferred. Please submit curriculum vitae, astatement outlining teaching experience and philoso-phy, and three letters of recommendation to: HonorsBiology Search Committee, The Honors College,212 MD Anderson Library, University of Hous-ton, Houston, TX 77204-2001. UH is an EqualOpportunity/Affirmative Action Employer. Minorities/Wom-en/Veterans/Persons with Disabilities are encouraged to apply.
THREE BIOLOGY FACULTY POSITIONSThe Department of Biology invites applications for
three tenure-track faculty positions at the rank of AS-SISTANT/ASSOCIATE PROFESSOR. A doc-toral degree and record of research productivity arerequired; postdoctoral training and teaching experi-ence are preferred. (Position 1) Microbiologist withinterests in teaching microbial physiology and/or en-vironmental microbiology preferred. (Position 2)Plant biologist with an interest in teaching plant phys-iology, plant taxonomy, and/or botany. (Position 3)Area of expertise is open, but an interest in developingan interdisciplinary, cross-curriculum research pro-gram is preferred. For more details and applicationinstructions,visitusatwebsite:http://www.westga.edu/��biology/.
The State University of West Georgia is committed toincreasing the diversity of our faculty and strongly encouragesapplications from minorities and women.
POSITIONS OPEN POSITIONS OPEN POSITIONS OPEN
17 SEPTEMBER 2004 VOL 305 SCIENCE Science Careers www.sciencecareers.org1842
THE UNIVERSITY OF SOUTH DAKOTASCHOOL OF MEDICINE
CHAIR, DEPARTMENT OF PSYCHIATRY/DIRECTOR, BRAIN RESEARCH CENTER
The University of South Dakota School of Medicine isseeking a person to both Chair the school’s Departmentof Psychiatry and to direct development and imple-mentation of a Brain Research Center. The School ofMedicine is a community-based medical school withmultiple campuses whose mission is to produce pri-mary care physicians for South Dakota. Departmentfaculty are primarily located and employed by a singleaffiliated hospital in Sioux Falls, South Dakota, wherethe Adult and Child and Adolescent PsychiatryResidency Programs are located. Responsibility formedical student education and community serviceextend across the entire state. A free-standing, 92-bedacademic psychiatric hospital is scheduled for comple-tion in 2006. The Department Chair must have BoardCertification in Psychiatry, academic qualifications forappointment at Associate or Full Professor, anddemonstrated skills in research, education, and admin-istration. Excellent leadership and interpersonal skillsare necessary. Priority will be given to candidates witha proven track record in nationally funded neuro-psy-chiatric research, as well as experience in the educationof medical students and residents. Applicants musthave experience in the clinical practice of Psychiatryand be licensable in South Dakota. Applicants must send a curriculum vitae and namesand addresses of three references to: Office of theDean, Psychiatry Search Committee, 1400 W. 22ndSt., Sioux Falls, SD 57105. Applications will bereviewed until the position is filled. The University of South Dakota School of Medicineis an Equal Opportunity/Affirmative ActionEmployer committed to increasing the diversity ofits faculty, staff and students.
Faculty Position in Mouse Genetics/Genomics
McLaughlin Research Institute has opened a searchfor an innovative mammalian geneticist. Candi-dates should possess a doctoral degree and a recordof research excellence as a postdoctoral fellow or independent investigator. The applicant should
have, or be capable of developing, a productive independent researchprogram that can compete successfully for grant funding. Applicants with interests in animal models for human disease, stem cell biology and differ-entiation, or novel strategies for mutant production or genome modifi cation are particularly encouraged to apply. Candidates should be able to establishboth intramural and extramural collaborative projects.
McLaughlin Research Institute offers a unique opportunity for research programs with an emphasis in mammalian genetics. The Institute is a smallnon-profi t organization and offers a non-bureaucratic, interactive researchenvironment. The Institute is housed in a spacious modern researchbuilding with an excellent mouse facility that includes a transgenic and gene-targeting service.
For additional information see www.montana.edu/wwwmri. For specifi c questions about the Institute contact George Carlson, Pin-Xian Xu, JohnMercer, or John Bermingham at MRI, or any of the following members of our Scientifi c Advisory Committee: Irv Weissman, David Baltimore, David Cameron, Neal Copeland, Jeff Frelinger, Leroy Hood, Nancy Jenkins, or James Spudich.
Applications, including names of individuals we may contact for refer-ences, should be sent to:
George A. Carlson, Ph.D.Director, McLaughlin Research Institute
1520 23rd Street SouthGreat Falls, MT 59405
An Equal Opportunity/Affi rmative Action Employer
RESEARCH GENETICIST or RESEARCH MOLECULAR BIOLOGIST
GS-13/14/15Salary Range of $72,454 to $130,930 per annum
The Western Human Nutrition Research Center at the University of Cali-fornia, Davis, invites applications for a permanent, full-time Research Scientist to study the role of genetics in dietary, behavioral and other factors that regulate energy balance, the metabolism of related nutrients, and/or obesity co-morbidities such as diabetes or cancer. The candidate isexpected to establish a strong research program, as a member of a team that investigates the nutritional, biological, genetic and environmental factors that contribute to achieving and maintaining a healthy body weightand reducing risk of chronic disease. The position offers outstanding opportunities for collaborations within the WHNRC and at UC Davis, in human nutrition intervention and community studies.
A PhD or equivalent degree in genetics, molecular biology, nutrition, physiology, biochemistry or another biological science that includes train-ing in genetics and molecular biology is desired. Demonstrated relevant expertise in studies with humans, non-human primates, or other models, and research related to human nutrition, obesity and its co-morbidities is desirable. U.S. citizenship is required. For details and applicationdirections see: http:www.afm.ars.usda.gov/divisions/hrd/vacancy/resjobs/0357. Specifi c questions may be directed to Dr. Lindsay Allenat 530 752-5268 or Dr. Nancy Keim at 530 752-4163.
For a printed copy by mail call 301-504-1482. Announcement closes December 3, 2004.
USDA/ARS is an Equal Opportunity Employer and Provider.
www.ars.usda.gov
The Department of Biology at Southwestern University invites applications from broadly trained Evolutionary Biologists for the Lillian Nelson Pratt Endowed Chair in Biology. Preference will be given to applicants with expertise in developmental and/or molecular approaches. Appointment will be at a rank commensurate with the experience of the individual fi lling the position, to begin August 2005. A PhD in a relevant discipline, a strong commitment to undergraduate teaching, and a record of distinction in both teaching and research are required.
Teaching responsibilities will include upper-level Evolutionary Biology for majors, participation in theIntroductory Biology sequence, and possible additional courses as required by Departmental needs. The successful candidate may elect to participate in Southwestern’s interdisciplinary Environmental Studies Program. The successful candidate will be expected to maintain a research program that actively involves undergraduates.
Southwestern University is a selective, undergraduate institution committed to a broad-based liberalarts, sciences, and fi ne arts education. Southwestern currently enrolls approximately 1,250 students and maintains a student to faculty ratio of 10 to 1. The University’s endowment ranks among the highest per student of undergraduate institutions in the country. In addition to a number of other national organizations, Southwestern University is a member of two consortia of liberal arts colleges,the Associated Colleges of the South and the Annapolis Group. Located in Georgetown, Texas, 28 miles north of downtown Austin, Southwestern is affi liated with The United Methodist Church. Southwestern University is committed to fostering a diverse educational environment and encourages applications from members of groups traditionally under-represented in academia. For information concerning the University, visit our web site at www.southwestern.edu.
Interested persons should send a letter of interest, curriculum vitae, statements of teaching and researchphilosophies, graduate and undergraduate transcripts (unoffi cial), and three current letters of recom-mendation to: Kendra Clovis, Faculty Secretary - Biology Search, Southwestern University, P.O.Box 770, Georgetown, TX, 78627-0770.
Applications received by October 22, 2004 will receive full consideration. For more information, contact the Biology Department Chair, Dr. Rebecca Sheller, [email protected].
Southwestern University is an Equal Opportunity Employer. EOE/M/F
Lillian Nelson Pratt Endowed Chair
PHYTOCHEMISTThe Department of Plant Biology at Southern Illi-
nois University, Carbondale (SIUC) has an openingfor a tenure-track ASSISTANT PROFESSORworking in any area of plant biochemistry, secondarymetabolism, phytopharmacognosy, or medicinalcompounds/nutraceuticals. Research should focuson model or non-agricultural plants, or utilize a sys-tems biology approach. Demonstrated experiencewith modern separation techniques is desired. Startupincludes a new high-performance liquid chromatog-raphy and gas chromatography. A Ph.D. in a relevantdiscipline is required. Applicants must have a record ofpeer-reviewed publications. Postdoctoral experienceand/or past evidence of external funding are pre-ferred. Candidates are expected to develop an exter-nally funded research program. The successful appli-cant will teach at the undergraduate level and offergraduate courses in the candidate’s field of expertise.Candidates should send a letter of application, curric-ulum vitae, representative publications, three lettersof reference, and statements of research goals andteaching philosophy to: Dr. Stephen Ebbs (e-mail:[email protected]) Search Committee Chair,Department of Plant Biology, Southern IllinoisUniversity, Carbondale, IL 62901-6509. De-partment and University information can be foundat website: http://www.science.siu.edu/plant-biology/. Review of applications begins October11, 2004, and will continue until the position isfilled. SIUC is an Affirmative Action/Equal OpportunityEmployer that strives to enhance its ability to develop adiverse faculty and staff, and to increase its potential to servea diverse student population. All applicants are welcome andencouraged and will receive consideration.
FACULTY POSITIONS, BIOLOGICALCHEMISTRY
University of Massachusetts, AmherstDepartment of Chemistry
Applications are invited for two tenure-track facultypositions in the areas broadly defined as experimentalbiological chemistry and biomaterials to begin in Sep-tember 2005. Individuals are sought who will developresearch programs at the interface of chemistry andbiology. Successful applicants will apply chemical ap-proaches to current problems in biology and/or bio-logical approaches to current problems in chemistry,in areas that are complementary to and synergisticwith an interdisciplinary and interdepartmental groupof faculty (visit website: http://www.chem.umass.edu/ for details). The search targets the AS-SISTANT PROFESSOR level, although outstand-ing applicants for higher ranks will be considered.Salary will be commensurate with qualifications andexperience. Evaluation of applications will begin onNovember 1, 2004, and continue until the position isfilled. Candidates should submit curriculum vitae,statements of research and teaching plans, and ar-range to have three letters of recommendation sentto: Faculty Search Chair, Department of Chemis-try, 701 Lederle Graduate Research Tower, Uni-versity of Massachusetts, 710 North PleasantStreet, Amherst, MA 01003-9336. The University ofMassachusetts is an Affirmative Action/Equal OpportunityEmployer.
The Department of Ecology and Evolutionary Biol-ogy, Tulane University, invites applications for twotenure-track positions, one in evolutionary systematicsand one in plant ecology, at the level of ASSISTANTPROFESSOR. See website: http://www.tu-lane.edu/˜eeob/faculty_search.html for details oneach position. Send curriculum vitae, statements ofresearch and teaching interests, selected publications,and names and addresses of three references to: eitherEvolutionary Systematist Search or Plant EcologistSearch at the Department of Ecology and Evolu-tionary Biology, 310 Dinwiddie Hall, Tulane Uni-versity, New Orleans, LA 70118-5698. Review ofapplications will begin October 14, 2004, and thesearches will remain open until the positions are filled.Tulane University is an Affirmative Action/Equal EmploymentOpportunity Employer.
DEPARTMENT HEADPlant Pathology, Physiology, and Weed ScienceThe College of Agriculture and Life Sciences invites
applications for the position of Professor and Head ofthe Department of Plant Pathology, Physiology, andWeed Science. The Department has 26 faculty mem-bers, with outstanding research programs in molecu-lar biology, functional genomics, and basic biology ofplant-microbe interactions, plant-plant interactions,abiotic stress physiology, metabolic engineering, con-ventional plant protection approaches, and weed bi-ology/management. A full position description andadditional information on departmental programs isavailable at website: http://www.ppws.vt.edu. Ap-plicants should complete a faculty application andsubmit complete curriculum vitae, a statement of in-tent, and names, addresses, and telephone numbers offive references online at website: http://jobs.vt.edu. Review will begin on October 1, 2004, andcontinue until the position is filled. Additional inquir-ies should be directed to: Mr. Don Ball, Fralin Bio-technology Center, Virginia Tech, at e-mail:[email protected] or by telephone: 540-231-6934.
Equal Opportunity/Affirmative Action Employer.
The Vollum Institute is seeking an outstanding sci-entist for a FACULTY APPOINTMENT. We areparticularly interested in individuals with a researchfocus in the general areas of molecular and cellularneuroscience, molecular genetics, and/or mecha-nisms of signal transduction. Although we would liketo fill this position at the ASSISTANT PROFES-SOR level, applications at more advanced levels willalso be considered. We offer an attractive startuppackage and the opportunity to work in an outstand-ing scientific environment that includes strong ties torelated departments at Oregon Health & ScienceUniversity. Applicants should have a strong record ofresearch, the potential to develop an independent,funded research program, and an interest in traininggraduate students. Candidates with a Ph.D. and/orM.D. and several years of postdoctoral experienceshould apply by November 15, 2004, sending a copyof their curriculum vitae, a description of researchplans and goals, and the names of three references to:
Vollum Faculty Search Committeec/o Richard H. Goodman, M.D., Ph.D.
Vollum Institute, L474Oregon Health & Science University
3181 SW Sam Jackson Park RoadPortland, OR 97201-3098
Website: http://www.ohsu.edu/vollumThe Vollum Institute is an Equal Opportunity/Affirmative
Action Employer committed to maintaining diversity in itsfaculty.
CHEMICAL OR BIOCHEMICALENGINEER
ProMetic BioSciences is a leading international bio-pharmaceutical company specializing in research, de-velopment, manufacture, and commercialization ofproducts and applications for the biopharmaceuticalindustry. The Research and Development Depart-ment of ProMetic BioSciences is searching for aChemical or Biochemical Engineer to work on spon-sored projects in laboratories in the Chemical Engi-neering Department at North Carolina State Univer-sity. Candidates should have a Ph.D. preferably withone-to-three years experience in process developmentand device design, particularly on membranes andchromatography, for the purification, detection, andremoval of proteins and/or pathogens such as prionprotein, viruses, and toxins. Forward curriculum vitaeto: Professor Ruben Carbonell, Chemical Engi-neering Department, North Carolina State Uni-versity, Campus Box 7006, Raleigh, NC 27695-7006. Fax: 919-515-5831. E-mail: [email protected]. ProMetic website: http://www.prometic.com.
CYTOGENETICS POSITIONDepartment of PathologyNorthwestern University
Feinberg School of MedicineMedical Director of Cytogenetics. Applications are
invited for a full-time, continuing tenure-track ap-pointment at the rank of ASSOCIATE PROFES-SOR/PROFESSOR level in the Department of Pa-thology, Northwestern University, Feinberg Schoolof Medicine, Chicago, to serve as Medical Director ofthe Cytogenetics Program, which will include prena-tal and tumor cytogenetics at the Northwestern Me-morial Hospital. This individual should hold M.D., orM.D./Ph.D. or Ph.D. degree(s) and be board certi-fied/eligible in clinical pathology, and/or medicalcytogenetics, as well as eligible for an unrestrictedmedical license in the state of Illinois. Full servicelaboratories in diagnostic molecular pathology, mo-lecular microbiology, FISH Laboratory, diagnosticbacteriology, virology, mycobacteriology, mycology,and parasitology are located in a superb physical facil-ity. Direction of these laboratories includes responsi-bility for College of American Pathologists accredita-tion. This individual is expected to establish a vigor-ous independent and interactive research program inbasic and/or translational research areas and requiredparticipation in the training and education of resi-dents and fellows. Salary and rank will be commensu-rate with experience. The start date for this positionwill be September 1, 2005. Please submit your curric-ulum vitae, a statement of areas of interest, expertiseand strengths, and names of three references to: Ja-nardan K. Reddy, M.D., Chair, Department ofPathology, Northwestern University, FeinbergSchool of Medicine, 303 East Chicago Avenue,Chicago, IL 60611, or to: Nancy Starks via e-mail:[email protected] no later than November30, 2004.
Northwestern University is an Affirmative Action/EqualOpportunity Employer. Hiring is contingent upon eligibility towork in the United States. Women and minorities are encour-aged to apply.
TENURE-TRACK FACULTY POSITIONSNorthwestern University
The Department of Biochemistry, Molecular Biol-ogy, and Cell Biology (BMBCB) seeks two outstand-ing scientists whose research addresses how individualmolecules combine to form complex structures thatcarry out the work of the cell. We are particularlyinterested in work on the biochemical and biophysicalaspects of molecular machines or the cell biology ofcomplex assemblies. The successful candidate will joina vibrant interdisciplinary community working on re-lated problems. Northwestern is expanding the lifesciences and has recently opened a new building, thePancoe/ENH Pavilion (website: http://www.biochem.northwestern.edu). Applicants shouldsubmit a cover letter, curriculum vitae, research sum-mary and statement of future research goals, andstatement of teaching experience and interests, andarrange for four letters of recommendation to be senton their behalf. Materials should be submitted elec-tronically as Adobe Acrobat or Microsoft Word filesto e-mail: [email protected] using “BM-BCB Search” as the subject. Mail correspondencemay be sent to: Faculty Search Committee, BM-BCB, 2205 Tech Drive, Northwestern University,Evanston, IL 60208-3500. Review will commenceimmediately and remain active until the positions arefilled.
Affirmative Action/Equal Opportunity Employer. Womenand minorities are especially encouraged to apply.
The Department of Biology at the University ofColorado at Colorado Springs (UCCS) invites appli-cations for a tenure-track ASSISTANT PROFES-SOR position in biochemistry. Review of applicationswill begin in October 2004. The academic appoint-ment begins August 2004. For details go to website:http://www.uccs.edu/��biology/Search.htm.The University of Colorado is an Equal Opportunity/Affir-mative Action Employer and encourages a diversity of appli-cants.
POSITIONS OPEN POSITIONS OPEN POSITIONS OPEN
17 SEPTEMBER 2004 VOL 305 SCIENCE Science Careers www.sciencecareers.org1844
Department of GeosciencesPRINCETON UNIVERSITY
The Department of Geosciences at Princeton University is seeking applications for a new tenure-track faculty position in the areas ofsolid-earth geophysics or geochemistry. We anticipate hiring at theassistant professor level, although candidates at a higher rank may be considered under exceptional circumstances. We are particularly interestedin outstanding individuals who will interact with and complementexisting research programs in global seismology, mineral physics,the physics of earthquakes, and structural geology (see our website at http://geoweb.princeton.edu). Examples of appropriate research areas include, but are not limited to, computational dynamics of the mantle and/or lithosphere, crustal deformation and active tectonics, physical or chemical evolution of the Earth or terrestrial planets, mantle petrology, earthquake seismology, and mineral or rock physics.
Applicants should send a curriculum vitae, including a publication list, a statement of research and teaching interests, and contact information for three references to: Search Committee, Department of Geosciences, Guyot Hall, Princeton University, Princeton, NJ 08544. The starting date is fl exible, ranging up to September 2006. Evaluation of applications will begin immediately; interviews of candidates will begin in September 2004 and continue until the position is fi lled.
For general information about applying to Princeton and how toself-identify, please link to http://web.princeton.edu/sites/dof/ApplicantsInfo.htm.
Princeton University is an Affi rmative Action Equal Opportunity Employer; women and members of minority groups are
encouraged to apply.
������� ��������� ���������������� ���������������
Z@J � Q� ������ �J� �X �@J ��XJ [Q�J�QJ�R �@J�J�����J�� �X�@J�������R ��Z �@J�J�����J�� �X ���Q@J������ ��Z �JQ ������[� ��J�� [���J �����J ����Q������ X�� ��� �J� �JZ��J� �J����Q� X�Q ����������� �� ���������R ����Q���J �� ��XJ���� J�J �� \����Q������[���@�� ]J ��J �����Q ��� ���J�J��JZ �� ��Q����JQ ��Q������[���@J�� ����J����[ �J�J��Q@ J�QJJ�QJ ��Z ���J�J��� ���JQ@������Q J������[�R �J�\���J ����J���R ^�� ��Z ^�������J�� ���J��Q�����R �� @�����J �JQJ����� �� \ �Z �� J������[���J�[�@� �� J�� [���J�
����Q������ �@� Z ��Q ZJ Q ��J�� Q ���Q � ����JR � � ����� �X���� �J�J��Q@ J��J��J�QJR ��Z � ����J�J�� �X X � �J �J�J��Q@ [������ �ZZ�����R �@�JJ J��J�� �X �JXJ�J�QJ X�� ����Q���� �� �����������XJ���� J�J �@� Z \J �J�� ���
���� ����������� J���� ��� JJ����� �� ����������� �� ����� �� ������
��������� �� �������K�� ��������� J��� L��������
L�������� ��� �� �����
����Q�������� \J �J��J�JZ �� �@J� ��J �JQJ��JZ�����J�JZ �����Q������ �JQJ��JZ \� �������� �� ���� �� �JQJ��J ���������
���� ����� �� ��������� �� ���������� ����������������������� ��� ��� ��������� �� ��� ����������
���������� ��
�����# �������� �� �����������#
�� ���� �� ����������� ���������� ��� ���� ������������ ������������������� �� ����������� ��������� ��������� �� ��� ���� � ������������ ����������� ����������� �� ����������� ���������� ���������������������� ���������� ��� ���������� ���������� �� ������
�����# �������� �� ���� ����������
�� ���� �� ����������� ���������� ��� ���� ����������� �������������������� ������ ������������� ���������� �� ����������� ��� ���� ����������� ���� ���������� �� ������� ��������
������������ �� ������������ ��������� ���� � ���������� �� ��� �������������������������� �������������������������� �������������� � �������� �� ����������� �� ������������� ��� �������� ������������� �� ������� � ������ ���������� ����� �������� �������������������������� � �������� �������������� �� ��� ����� �� ���������������������������� �� �� ����� �� ��� �������������������� ����������������� ������ ���������� ����� �� ������������ ��� ��������� ��������� ������������ ����������� ��� ������������ ����� ��������������������� ����� �� ������
������������ ������ ������� ��� �������� �� �������� ��������� � ����������� ��������� ��� �������� ��� ���� � ��������� ��� ���������� ��������������� ������ ��������� ��� � ������� � ���� �������� ����������������� ����� �������� ������ ��� �������� ���������� ��� �� �� ����� ������������ ������ ��������� ��� ��� ����� ������� � �������� ���� ����� ������������� ���������� �� ��������� ���� ������ ������ � ������������ �������� �� ������� ��� �����
��� ���������� ���� ������ �� ���� ������ ���� ������� ������� ��������� ������������ ��� ��������� ���� �� ��������� ���� ����� �� ������ � ��� ��� ��� ��������� � �������������
���� ����� �� ��������� �� ���������� ������������ �������������� ��� ��������� �� ��� ����������
&��������� ����
CCSG ADMINISTRATORThe University of Texas M. D. Anderson Cancer Center (MDACC) is seeking a talented individual to provide administrative coordination for its comprehensive Cancer Center Support Grant (CCSG). Currently, MDACC holds the largest number of NCI grants and the largest amount of NCI funding among academic institutions. The CCSG grant supports 19 programs and 19 shared resources. Working with the PI of the CCSG, President of MDACC, and the Co-PI of the CCSG, Vice President for Translational Research, the CCSG Administrator will coordinate, analyze, and support all aspects of our Cancer Center Support Grant. Other duties include developing databases, preparing budgets, initiating grant renewals, writing grants, and coordinating all financial and reporting activities. To qualify for this key position, you must possess a degree, preferably a Master’s or Ph.D.in Biology, Chemistry, Business or Health Administration. The successful candidate must also have had at least five years’ experience in preparing grants, developing budgets, and managing resources.
Qualified candidates may contact: Dr. Robert Bast Jr.,E-mail: [email protected]; Ph: 713-792-7743.
M. D. Anderson Cancer Center is an equal opportunity employer and does not discriminate on the basis of race, color, national origin, gender, sexual orientation, age, religion, disability or veteran status except where such
distinction is required by law. All positions at the University of TexasM. D. Anderson Cancer Center are security sensitive and subject to
examination of criminal history record information.Smoke-free and drug-free environment.
FACULTY OPENING IN EXPERIMENTALBIOLOGICAL PHYSICS
Washington University in St. LouisThe Department of Physics invites applications for a
tenure-track appointment in experimental biophysicsat the ASSISTANT PROFESSOR level, to beginfall 2005.
We seek individuals with an outstanding researchrecord and independent creativity in applying experi-mental tools combined with quantitative models tostudy living systems at an integrated level. Applicantsshould have a strong background in physics and anaptitude for teaching and mentoring both undergrad-uate and graduate students. The successful candidatewill complement and reinforce the Department’sstrength in biologically oriented physics and may takeadvantage of the top-ranked Washington UniversityMedical School and the vigorously growing Depart-ment of Biomedical Engineering. Applications will beconsidered until the position is filled, but priority willbe given to those received by November 15, 2004.Applicants should send their curriculum vitae with apublication list and a statement of research interestsand future plans, and ask three references to sendletters of evaluation. Correspondence should be sentto: Professor John W. Clark, Biological PhysicsSearch, Department of Physics, CB 1105, Wash-ington University, 1 Brookings Drive, St. Louis,MO 63130-4899 or by e-mail: [email protected] University is an Equal Opportunity/AffirmativeAction Employer. Women and minorities are encouraged toapply.
The Division of Cardiovascular Medicine at theBrigham and Women’s Hospital, directed by PeterLibby, M.D., invite applications for a faculty positionat the level of INSTRUCTOR/ASSISTANTPROFESSOR. Candidates should have an M.D.,Ph.D., or equivalent degree with a strong interest inbasic research in the areas of cardiac developmentand/or regeneration. It is anticipated that the candi-date will develop an independent research and secureextramural funding. Academic rank and salary will becommensurate with experience. The candidate willjoin a newly established Program in CardiovascularTranscriptional Biology under the direction ofMukesh K. Jain, M.D.
Applicants should send their curriculum vitae, sum-mary of present and future research plans, and namesof three references to:
Mukesh K. Jain, M.D.Chair, Search CommitteeCardiovascular Division
Brigham and Women’s HospitalThorn Research Building, Room 1127
20 Shattuck StreetBoston, MA 02115
E-mail: [email protected] Brigham and Women’s Hospital is an Equal Oppor-
tunity Employer, and encourages applications from female andminority candidates.
The Division of Pediatric Pulmonology at CWRU,Rainbow Babies and Children’s Hospital at CaseWestern Reserve University (CWRU) is seeking aPHYSICIAN-SCIENTIST interested in conduct-ing basic science and/or translational research in asth-ma. The Division operates a large children’s asthmacenter and is actively involved in a number of federallyfunded clinical trials. Areas of active research based inthe Division include cell signaling, airway and inflam-matory cell biology, and the genetics of inherited re-spiratory diseases. The Division currently includes 10full-time M.D.s and seven Ph.D.s; ample laboratoryspace and resources, as well as protected time, areavailable. Applicants should be board certified/boardeligible in pediatric pulmonology or allergy. Pleasesend inquiries or applications electronically to: Car-olyn M. Kercsmar, M.D. (e-mail: [email protected]). Applications should include full curriculum vi-tae, statement of goals, and names of three references.CWRU is an Affirmative Action/Equal Opportunity Employ-er and women and minority applicants are encouraged to apply.
PROTEIN MASS SPECTROMETRYDartmouth Medical School and the Norris Cotton
Cancer Center invite applications for a tenure-trackfaculty position at the level of ASSISTANT or AS-SOCIATE PROFESSOR. The ideal candidate is aninnovative, interactive protein mass spectrometristwith a strong research program. Qualified individualsshould submit a letter of application with a statementof career goals and curriculum vitae to: Dr. CharlesBrenner, Norris Cotton Cancer Center, One Med-ical Center Drive—Rubin 733, Lebanon, NH03756. Three letters of recommendation should besent to the same address. Dartmouth is an Equal Oppor-tunity/Affirmative Action Employer and encourages womenand minority candidates to apply.
ASSISTANT/ASSOCIATE PROFESSORCell/Developmental Biology
Eckerd CollegeFull-time, tenure-track position beginning fall
2005. Teaching responsibilities include introductorycourses in cell/molecular biology and genetics and anupper-level course in developmental biology. Dem-onstrated interest and potential in undergraduateteaching are essential. The successful candidateshould establish a research program involving under-graduate students and will contribute to anticipatedrevision of the biology program. Participation in aninterdisciplinary, values-oriented general educationprogram is expected, including a regular rotation in atwo-semester freshman course that explores westernand non-western traditions. Send letter of applicationincluding statements of teaching and research inter-ests, curriculum vitae, undergraduate and graduatetranscripts, and three letters of reference by October30, 2004, to: Dr. Steven H. Denison, Natural Sci-ences, Eckerd College, 4200 54th Avenue South,St. Petersburg, FL 33711. Telephone: 727-864-8456; fax: 727-864-8382; e-mail: [email protected]. Eckerd College is an outstanding collegeof the liberal arts and sciences with strong programs inbiology and marine biology and is located on TampaBay in St. Petersburg, Florida. Candidates with re-search interests in marine organisms are encouragedto apply. No electronic applications will be accepted.Equal Opportunity Employer/Minorities/Females/Veterans/ADA.
NEUROSCIENCE FACULTY POSITIONThe University of North Carolina at Chapel Hill
The Department of Cell and Molecular Physiologyin the School of Medicine invites applications for atenure-track faculty position (rank dependent onqualifications). Applicants must be at least two yearspostdoctoral. We seek candidates using novel ap-proaches to study the physiology or pathophysiologyof the nervous system. Preference will be given toindividuals with established record of exciting, con-temporary work on integrative neural function. Anattractive startup package and new laboratory spaceare available. The Department’s faculty are expectedto contribute to teaching of graduate and medicalstudents.
Please submit the names of four potential referenc-es, curriculum vitae, statement of the proposed re-search program, and career goals by e-mail to:
Neuroscience Search ChairEdward R. Perl
Department of Cell and Molecular Physiology5109 Neuroscience Research Building CB #7545
School of MedicineThe University of North Carolina at Chapel Hill
Chapel Hill, NC 27599-7545E-mail: [email protected]
Closing date for first consideration: October 11,2004. UNC is an Equal Opportunity Employer.
FACULTY POSITIONThe Fred Hutchinson Cancer Research CenterThe Division of Human Biology at the Fred
Hutchinson Cancer Research Center is soliciting ap-plications to fill an open faculty position in the broadareas of genomics and genetics. Applicants with out-standing accomplishments, particularly in the areas ofcomplex disease-gene mapping, population genetics,or large-scale approaches to functional genomics, pro-teomics, or bioinformatics are encouraged to apply.
The Human Biology Division fosters interdiscipli-nary, collaborative research at the interfaces of basic,clinical, and population sciences in order to furtherour understanding of human biology, cancer, andother complex human diseases.
The Division occupies state-of-the-art research lab-oratories on a new lakeside campus. The Center offersoutstanding shared resources, including DNA array,sequencing, and proteomics facilities. The Center hasactive graduate-student and postdoctoral trainingprograms and offers exceptional opportunities for sci-entific interactions with other investigators in theSeattle area.
Additional information about the Division can befound at website: http://www.fhcrc.org/science/human_biology/.
Candidates should send curriculum vitae, a concisestatement of research plans, and three letters of refer-ence to: Human Biology Faculty Search Commit-tee, Fred Hutchinson Cancer Research Center, Di-vision of Human Biology, Mailstop: C3-168,1100 Fairview Avenue North, P.O. Box 19024,Seattle, WA 98109-1024. The application deadlineis October 15, 2004.
The Fred Hutchinson Cancer Research Center is an EqualOpportunity Employer committed to work force diversity. Ap-plications from female and minority candidates are stronglyencouraged.
WATER RESOURCE SCIENTISTBaylor University
Baylor University seeks a candidate with skills inwater resource modeling and/or aquatic chemistryfor a tenure-track faculty position, ASSISTANTPROFESSOR level, beginning August 2005. Ph.D.or equivalent is required. Position responsibilities:teach at graduate and undergraduate levels and estab-lish a vigorous, externally funded research program.Will participate in the new interdisciplinary Ph.D.program in ecology and environmental sciences andin the Center for Reservoir and Aquatic Systems Re-search (website: http://www.baylor.edu/crasr).Applications will be reviewed beginning October 15,2004, and will be accepted until the position is filled.To ensure full consideration, your application must becompleted by November 5, 2004. Send applicationletter, statements of research interests and teachingphilosophy, curriculum vitae, reprints of up to threepublications, graduate and undergraduate transcripts,representative teaching evaluations, if available, andcontact information for three references to: SearchCommittee Chair, Department of EnvironmentalStudies, One Bear Place #97266, Baylor Univer-sity, Waco, TX 76798-7266. Telephone: 254-710-3405; fax: 254-710-3409; e-mail: [email protected];website:http://www.baylor.edu/Environmental_Studies/. Baylor is a Baptistuniversity affiliated with the Baptist General Conven-tion of Texas. As an Affirmative Action/Equal EmploymentOpportunity Employer, Baylor encourages minorities, women,veterans, and persons with disabilities to apply.
ASSISTANT PROFESSOR OF BIOLOGY.Saint Vincent College invites applications for atenure-track position beginning fall 2005. Require-ments include a Ph.D. and commitment to under-graduate education in a liberal arts setting. Postdoc-toral experience is preferred. Teaching responsibili-ties include general biology, comparative vertebrateanatomy, a course for nonscience majors, either de-velopmental biology or histology, and supervisionof required senior research projects. Please see de-tails and application procedures at website: http://www.stvincent.edu/services/hr/posting.jsp.Equal Opportunity Employer/Affirmative Action.
POSITIONS OPEN POSITIONS OPEN POSITIONS OPEN
17 SEPTEMBER 2004 VOL 305 SCIENCE Science Careers www.sciencecareers.org1846
��� ���������� � ������� �� ���� ! ���� �� ���������" ����#���� ��� �������� ��� ������� ��������� �� ��������% ��������� ������ ������� �������� �� ������� � �����*����� ������������� ���%����� +������� ��� ������ 8� ��#� �� ����< �����=������� � ��� �������� ���%��� �� 8� �����#� ��<������� ��������� �������� >���� � �������� ���� � ������� �� ����������� �� >%��%" ! ����� ������ �%� �� ������������������"!��� �������� �� ����%����#� �������" ����� ������ ������#��� �%� �� X�������" !����� �� �� ��� �� ��������
��� �������� ������� 8� ��#� �� ��" [���� �� �� ��\[�����%���]�^ �� ���� <� � �%�< � �� ���� �� �����
�� ���� ���� �<��� ���� ! ���� �� ���������" ��" � ���� #������������������
��������� ��� ������ ���� ��<��� � ������� �� #����" � ���������� �������� ��������� �� %�� �" � ��% 8��� ��� ���� � �������������� <� ��#��<�� _" `{{|" ��}
������ ������� ��!����" +����� !��������~����<��% X�� ��% +`|
���� ��� ��� � �� ������`{{ ����� +����� +����������" �� ���{�
���� ��������� � �� ��������� ����� ��� ���� ���������� �������� ����������� ���� �����"���#��������� ��� ������� � ��������
�%����� '������ ������ ������
���������" ���������
James P. Wilmot Cancer CenterUniversity of Rochester
Human Cancer Biology
The Wilmot Cancer Center and the Department of BiomedicalGenetics at the University of Rochester Medical Center invite applications from candidates interested in the biology of solid tumors. The Medical Center offers exciting opportunities for interdisciplinary/translational cancer research in an interactiveenvironment with strong programs in cancer and stem cellbiology, cell signaling, genetics in model organisms, genom-ics, proteomics and bio-mathematics. This is a tenure-track position at the Assistant/Associate Professor level. Candidatesshould have a strong record of accomplishment and evidence of extramural funding.
To apply, submit curriculum vitae, statement of researchinterests/plans, and the names of three referees via e-mail to:
Dr. Hartmut LandChair, Biomedical Genetics
Director, Basic Sciences, J.P. Wilmot Cancer CenterE-mail: [email protected]
See: http://www.urmc.rochester.edu/Aab/bg/http://www.stronghealth.com/services/cancer
The University of Rochester is an Equal Opportunity Employer.
PHYSIOLOGY UCLA
Assistant or Associate Professors (2)
TheDepartment of Physiology at the David Geffen School of Medi-cine at UCLA invites applications for tenure-track faculty positions, preferably at the level of Assistant or Associate Professor.
We are especially interested in candidates in molecular physiology withinterests in functional genomics, proteomics, or transgenics. Areas of departmental strength include molecular biophysics and cardiovascularresearch, and candidates in these disciplines are encouraged to apply. However, we will consider applicants in all areas of modern physiology.Areas in which we might hope to expand include renal and respiratory physiology. Candidates are expected to have a strong background in cellular and molecular biology and a demonstrated interest in the study of physiological systems in model organisms.
The successful candidate will be expected to develop an independent research program and participate in the teaching mission of the Depart-ment for medical, dental, and graduate students.
Interested applicants should e-mail their curriculum vitae, a letterwith a statement of research interests and career goals to Dr. Thomas O’Dell at [email protected]. Applicants should also arrange for three letters of reference to be sent to Dr. O’Dell atthe same e-mail address.
UCLA is an Affi rmative Action/Equal Opportunity Employer. Women and minorities are encouraged to apply.
The Cancer Institute of the NYU School of Medicine, under the direction ofDr. Steven Burakoff, announces an unprecedented expansion in its programsin cancer biology at the new Joan and Joel Smilow Research Building.
Faculty Recruitmentin Basic and Translational ResearchWe are seeking up to ten new tenure track faculty recruits engaged in basicand/or translational research related to cancer. All will be members of theNYU Cancer Institute with primary academic appointments in one of thebasic science or clinical departments. Laboratories will be available in theSmilow Research Building, currently under construction. Most positionswill be at the Assistant Professor level, although a few Associate orProfessor level recruitments will be considered. Areas of interest include,but are not limited to, Animal Models of Cancer, CancerImmunology, Cancer Neurobiology, DNA damage andCheckpoint Control, Molecular Carcinogenesis, MolecularControl of Cell Proliferation and Stem Cell Biology.Investigators whose research will enhance the translation of basic researchfindings into new therapeutic interventions and the design of new clinicaltrials are encouraged to apply. Successful applicants should hold an MDand/or PhD with established reputations in these areas of research andvisibility at the national level.
Interested investigators are encouraged to visithttp://www.med.nyu.edu/smilowcenter to learn more about theNYU Cancer Institute, qualifications for candidates and our recruitmentprocess. Qualified candidates can apply by following the instructionsfound on the web site. We are an equal opportunity employer and providea drug-free workplace.
FACULTY POSITIONS IN CHEMISTRYAND
BIOCHEMISTRYUniversity of California Santa Barbara
The Department of Chemistry and Biochemistry atthe University of California Santa Barbara announcesa search for a tenure-track faculty member to begin infall 2005 at the ASSISTANT PROFESSOR level.Outstanding candidates with research and teachinginterests in all sub-areas of inorganic chemistry includ-ing bioinorganic, inorganic materials, and organome-tallic chemistry are invited to apply. In addition tocontributing to the research, teaching, and servicemissions of the Department of Chemistry and Bio-chemistry, we anticipate campus-wide interactions ininterdisciplinary programs between departments inthe Colleges of Letters and Sciences and Engineering,along with other University-based Centers and Insti-tutes. Applicants should submit curriculum vitae, de-scription of their research plans, graduate and under-graduate teaching interests, and arrange to have threeletters of recommendation sent on their behalf to:Faculty Search Committee, Department of Chem-istry and Biochemistry, University of CaliforniaSanta Barbara, Santa Barbara, CA 93106-9510.Review of applications will begin October 1, 2004,and will continue until the position is filled. A Ph.D. isrequired at the time of appointment. The Departmentis especially interested in candidates who can contrib-ute to the diversity and excellence of the academiccommunity through research, teaching, and service.The University of California is an Equal Opportunity/Affir-mative Action Employer.
ANIMAL ECOLOGYUniversity of Wyoming
The Department of Zoology and Physiology at theUniversity of Wyoming invites applications for atenure-track position in animal ecology beginningAugust 2005 at the level of ASSISTANT PROFES-SOR, or at a higher rank for an individual with anoutstanding research and funding record. Ph.D. re-quired for faculty rank. Teaching responsibilities in-clude an introductory course in ecology or fisheriesand wildlife biology plus an upper-division course inthe candidate’s area of expertise. Research interestscan involve any aspect of animal ecology although afocus on spatial aspects of population dynamics andhabitat use would complement existing areas of ex-pertise in our Department. The candidate will be ex-pected to develop an extramurally funded researchprogram, advise undergraduates in our wildlife andfisheries biology major, and mentor graduate stu-dents. The candidate will be encouraged to interactwith natural resource agencies and with the Universityof Wyoming’s School of Environment and NaturalResources.
Review of applications will begin on November 1,2004. Applicants should send curriculum vitae, state-ments of research and teaching interests, and arrangeto have three letters of reference sent to: Chair, An-imal Ecology Search Committee, Department ofZoology and Physiology, University of Wyoming,Laramie, WY 82071-3166. Website: http://uwadmnweb.uwyo.edu/Zoology. The University ofWyoming is an Affirmative Action/Equal OpportunityEmployer.
CAREER IN OPTOMETRY, OPTOMETRICRESEARCH, OR TEACHING
The New England College of Optometry offers aunique program for those with a Doctorate in thesciences: biology, chemistry, physics, psychology,pharmacology, medicine, etc. Candidates have theopportunity to obtain the Doctor of Optometry(O.D.) degree in 27 months. The program beginsannually in early March. Employment opportunitiesexist in clinical practice, industry, optometric facultypositions, and research. Contact: the AdmissionsOffice, Department S, 424 Beacon Street, Boston,MA 02115. Telephone: 1-800-824-5526; e-mail:[email protected]. Website: http://www.ne-optometry.edu. Application deadline: Feb-ruary 1, 2005.
Nicholls State University (NSU) invites applica-tions for the position of ASSISTANT PROFES-SOR of molecular biology in the Department of Bi-ological Sciences. Visit website: http://www.ni-cholls.edu/hr for complete position announcementand application instructions. NSU is an Affirmative Ac-tion/Equal Opportunity Employer.
TENURE-TRACK FACULTY POSITION INMICROBIOLOGY
Indiana University, BloomingtonThe Indiana University (IU) Department of Biol-
ogy (website: http://www.bio.indiana.edu) andthe Interdisciplinary Human Biology Program in-vite applications for a Tenure-track Faculty positionin bacterial cell and molecular biology, with empha-sis on pathogenesis, including cellular microbiolo-gy. This position is part of a significant, continuingexpansion in the life sciences at IU Bloomingtonand represents an exceptional opportunity to join astrong Microbiology Program in the Department ofBiology and new interdisciplinary initiatives in hu-man biology and biotechnology linking togetherbiology, biochemistry, chemistry, and medical sci-ences. The successful candidate will be providedwith a competitive startup package and salary andwill have access to outstanding research resources.The successful candidate will be expected to developa vigorous externally funded research program andto participate in and develop courses at the under-graduate and graduate levels. Appointment is ex-pected to be at the ASSISTANT PROFESSORlevel, but outstanding SENIOR-LEVEL CANDI-DATES will also be considered.
Applicants should send curriculum vitae, a state-ment of research (past, present, and planned) andteaching interests, representative publications andpreprints, and arrange to have at least four letters ofrecommendation sent to: Malcolm E. Winkler, De-partment of Biology, Indiana University Bloom-ington, Jordan Hall, Room 142, Bloomington,IN 47405. Please address questions by e-mail:[email protected]. Review of applicantswill begin as soon as possible and continue until theposition is filled. Indiana University is an Affirmative Ac-tion/Equal Opportunity Employer. Women, minority candi-dates, and couples are encouraged to apply.
The Department of Biology of the University ofWaterloo invites applications for two tenure-track po-sitions at the ASSISTANT or ASSOCIATE PRO-FESSOR level in animal physiology. Applicants musthave a Ph.D. and postdoctoral experience and be pre-pared to establish an externally funded active researchprogram. We are particularly interested in candidatesusing cellular and/or molecular approaches to ex-plore an aspect of animal physiology. Duties includeresearch, teaching at the undergraduate and graduatelevels, and graduate student supervision. Candidatesshould be able to teach courses dealing with compar-ative animal physiology, reproductive animal physiol-ogy, endocrinology, and/or a specialized topicscourse within these disciplines. Salary will be com-mensurate with qualifications and experience. Appli-cants should send their curriculum vitae, the names ofthree individuals willing to furnish letters of reference,and an outline (one-to-two pages) of their proposedresearch program to: Chair, Department of Biolo-gy, Faculty of Science, University of Waterloo,200 University Avenue West, Waterloo, Ontario,Canada N2L 3G1.
The closing date for applications is November 15,2004, with a start date after May 1, 2005. Additionalinformation on the Department is available at web-site: http://www.sci.uwaterloo.ca/biology.
All qualified candidates are encouraged to apply; however,Canadians and permanent residents will be given priority. TheUniversity of Waterloo encourages applications from all qualifiedindividuals, including women, members of visible minorities,native peoples, and persons with disabilities.
FACULTY POSITIONPeripheral Nerve Regeneration
Johns Hopkins UniversityThe Departments of Orthopaedics and Neuro-
science, Johns Hopkins University, invite applicationsfrom scientists with outstanding training and poten-tial for a faculty position at the ASSISTANT or AS-SOCIATE PROFESSOR level. The appointmentwill be based in the Peripheral Nerve RegenerationLaboratories of the Department of Orthopaedic Sur-gery, and will include participation in the activities ofthe Department of Neuroscience. We seek a scientistwith a strong background in molecular neuroscienceto investigate factors contributing to the specificity ofperipheral axon development and regeneration. Thesuccessful candidate will be expected to collaboratewith ongoing studies as well as establish and maintaina strong extramurally funded research program. Com-mitment to excellence in teaching at the graduatelevel is also required. Candidates should send theircurriculum vitae, a statement of research goals, andcontact information for three references to: ThomasM. Brushart, M.D., Vice Chairman for Research,Johns Hopkins Orthopaedics, 601 N. CarolineStreet, Baltimore, MD 21287. E-mail:[email protected].
Johns Hopkins offers competitive compensation and compre-hensive benefits. As an Equal Opportunity Employer, we valuediversity.
FACULTY POSITIONS IN BIOCHEMISTRYUniversity of California, San Diego
The Department of Chemistry and Biochemistry ofUniversity of California, San Diego (website:http://chem.ucsd.edu) invites applications for ten-ure-track/tenured faculty positions in biochemistrywith a preference for candidates at the ASSISTANTPROFESSOR level. Candidates must have a Ph.D.and a demonstrated ability for creative research andteaching at the undergraduate and graduate levels.The Department will consider applicants in all areas ofstructural biology and biophysics for this position.Salary commensurate with qualifications and based onUniversity of California pay scale. Candidates shouldsend curriculum vitae, list of publications, reprints ofup to five representative papers, and a summary ofresearch plans to: Chair, Biochemistry Search Com-mittee 4-445S, University of California, San Di-ego, Department of Chemistry and Biochemistry,9500 Gilman Drive–0332, La Jolla, CA 92093-0332. Candidates should also arrange to have threeletters of reference sent under separate cover. Thedeadline for applications is October 8, 2004, but untilthe position is filled, all applications received will beassured full consideration. UCSD is an Equal Opportu-nity/Affirmative Action Employer with a strong institutionalcommitment to the achievement of diversity among its facultyand staff.
ASSISTANT PROFESSORBIOLOGICAL CHEMISTRY
The David Geffen School of Medicine at UCLAThe Department of Biological Chemistry is seek-
ing applications for a tenure-track faculty position inany area of biochemistry, or molecular, cell, anddevelopmental biology. The position is at the levelof Assistant Professor. The new faculty member willbe expected to develop a strong and creative re-search program and to contribute to the teachingmissions of the Department.
Selection of candidates will begin on November 1,2004, and will continue until the position is filled.Applicants should send curriculum vitae and a sum-mary of research interests and arrange for three lettersof reference to be sent to:
Gregory S. PayneChair, Search Committee
c/o Karen RonanHHMI—UCLA
5-748 MRLP.O. Box 951662
Los Angeles, CA 90095-1662The University of California is an Equal Opportunity
Employer.
POSITIONS OPEN POSITIONS OPEN POSITIONS OPEN
17 SEPTEMBER 2004 VOL 305 SCIENCE Science Careers www.sciencecareers.org1848
Vanderbilt University Medical CenterFaculty Positions in
Cell and Developmental BiologyThe Department of Cell and DevelopmentalBiology invites applications for several tenure-track positions at the rank of Assistant/Associate Professor. Our department covers a broad range of topics including cellular biology, cellularsignaling and traffi cking, cell cycle regulation, neurobiology, developmental biology and stem cell biology. Cell biologists using cellular, molec-ular, biochemical and/or genetic approaches are encouraged to apply. Candidates must have aPh.D. and/or M.D. degree, at least two yearspostdoctoral experience, a strong publicationrecord and strong potential for extramural fund-ing evident. Successful candidates will receive substantial start-up packages and be housed in newly constructed/renovated facilities. In addi-tion, there is a strong institutional commitment to core facilities, graduate programs, and aninterdisciplinary environment. Complete appli-cations should include curriculum vitae, reprints of recent publications, a brief statement of presentand future research plans, and three letters of rec-ommendation, solicited by the applicant. Reviewof applications will begin November 1, 2004,and will continue until the positions are fi lled. Please send materials to: Susan R. Wente, Ph.D.,Professor and Chair, Department of Cell and Developmental Biology, Vanderbilt UniversityMedical Center, 3120 Medical Research Build-ing III, Nashville, TN 37232-8240.
Vanderbilt University Medical Center is strongly committed to diversity in attracting faculty to fi ll these positions and is an Affi rma-tive Action, Equal Opportunity Employer.
Director of the Institute for Advanced Materials and Devices
Rutgers University seeks an outstanding scientist and academic leader to become the fi rst Director of the newly established Institute for Advanced Materials and Devices (IAMD). The primary mission of the Institute is to advance interdisciplinary research at the forefront of modern materials and devices. The IAMD is composed of approximately 75 faculty members drawnfrom various departments at the University, as well as several existing centersand laboratories. The Director will lead the coordination and integration of research and educational activities, develop new research and educational programs, seek new funding resources and serve as the Institute representativeto internal and external constituencies.
Major thrusts of the IAMD include multi-functional materials and devices, nanoscience and technology, sensors, theory and computational modeling. The Institute will also interface with the strong life sciences programs at Rutgers and the Robert Wood Johnson Medical School. It will develop innovative programs that foster close working relationships with industry, as well as other academic and governmental laboratories.
The Director will report to the Executive Vice President for Academic Affairs and will qualify for appointment at the rank of professor, to be made jointly between appropriate departments in the Rutgers School of Engineering and the Faculty of Arts and Sciences-New Brunswick. The successful candidate should have an international reputation for outstanding scholarly research in an area within the scope of the IAMD, demonstrated leadership in materials and devices disciplines, a keen interest in and appreciation for education, a proven record of external funding, and the ability to interact effectively with administrators, faculty, students, industry representatives, and government offi cials. The appointment starting date is fl exible. For more information aboutthe IAMD and how to submit nominations and applications for the position, visit the Institute website http://iamd.rutgers.edu.
An Affi rmative Action/Equal Opportunity Employer.
The Program in Molecular and Computa-tional Biology at the University of Southern California invites applications for multipletenure-track and tenured faculty positions.Our program continues to undergo sig-nifi cant expansion, including occupancy ofa new research building in Spring 2005. We are an interactive multi-disciplinary faculty looking for colleagues who will enhance and complement our present research strengths. Extramural funding is expected.
We seek scientists who use modern molecu-lar, genetic, or computational approaches to address fundamental molecular, cellular, ordevelopmental processes. Investigators withinthe disciplines of Evolutionary Biology, Neu-robiology, Plant Biology, Systems Biology, or Bioinformatics are especially encouragedto apply, although outstanding candidates in related fi elds will also be considered.
Review of applications will begin October 15, 2004. Please send a curriculum vitae, state-ment of research objectives, and three letters of recommendation to [email protected] additional information about our program,please visit http://www.usc.edu/dept/LAS/biosci/mcb/.
USC is an Affi rmative Action/Equal Opportunity Employer.
FACULTY POSITIONSTISSUE ENGINEERING AND REPAIR
The Hospital for Special Surgery, in conjunction with the Weill Medical College of Cornell University, is undertaking a major new initiative in tissue engineering and regenerative medicine. We are recruiting a Program Director and tenure track research faculty for a new Program in Tissue Engineering and Repair. An endowed Chair in Tissue Engineering has beenestablished at the Hospital to help meet this goal. The Hospital for SpecialSurgery is a leading hospital for musculoskeletal care, including treatmentof arthritis and osteoporosis, spine and sports injuries, and cerebral palsy and spina bifi da. The Research Division of the Hospital focuses on bone and cartilage physiology, tissue remodeling, infl ammation, autoimmunity, and the pathophysiology of orthopedic and rheumatic diseases.
Faculty in the Tissue Engineering and Repair Program will be respon-sible for developing an innovative and competitive program of research in tissue engineering, repair, or mesenchymal stem cell biology that will interface with existing research Programs in Musculoskeletal Integrity, Autoimmunity and Infl ammation, Arthritis and Tissue Degeneration, and Tissue Mechanics. There will be ample opportunity for collaboration withinvestigators at the adjacent Memorial Sloan-Kettering Cancer Center andRockefeller University. It is expected that faculty will establish links with the Weill Medical College of Cornell University in New York City and/or Cornell University in Ithaca and participate in the academic programs of Cornell University. Faculty will hold a joint academic appointment atCornell University.
HSS offers an extensive startup package and a highly competitive compen-sation package. Applicants should send a CV, a brief summary of researchaccomplishments and future objectives, and names and addresses of 3 references to: Dr. Lionel Ivashkiv, Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021.
An Equal Opportunity/Affi rmative Action Employer
Theoretical Population GeneticsUNIVERSITY OF CALIFORNIA, DAVIS
The Division of Biological Sciences, Univer-sity of California, Davis invites applicationsand nominations for a position in the Section of Evolution and Ecology at the tenure-trackASSISTANT, ASSOCIATE or FULL PROFES-SOR level. Candidates must have a Ph.D. (or equivalent) in the biological sciences or related fi elds. Candidates should have a strong record of research in theoretical population genetics, focusing on questions of interest to molecular population geneticists and molecular evolution-ists. The successful candidate will be expected to teach an undergraduate course in introductorybiology or evolution and to participate in theCore Course required of all fi rst-year graduate students in the Population Biology GraduateGroup.
Applicants should send the following items (as pdfs) to the Chair of the Theoretical Population Genetics Search Committee at [email protected]: curriculum vitae, description ofcurrent and projected research, summary ofteaching interests and experience, and up to fi vepublications. Applicants should also arrange to have three letters of recommendation sent bye-mail to [email protected]. Clos-ing Date: Open until fi lled, but all application materials, including letters of recommendation, must be received by November 1, 2004 to assure full consideration.
The University of California is an Equal Opportunity/Affi rmative Action Employer with a strong institutional commitment to the devel-opment of a climate that supports equality of
opportunity and respect for differences.
POPULATION/COMMUNITY ECOLOGISTDepartment of Biology
Indiana University, BloomingtonThe Department of Biology, Program in Ecology,
Evolution, and Behavior invites applications for anEcologist. We seek candidates with a conceptuallydriven research program utilizing theoretical, experi-mental, and/or field approaches to population and/or community ecology. The search is open to individ-uals working on any taxa, including microbes. Indi-viduals complementing department strengths in in-terspecific interactions, disease ecology, and plant-microbe interactions are particularly encouraged toapply.
We invite candidates at the tenure-track ASSIS-TANT PROFESSOR level, but outstanding candi-dates at any level will be considered. The successfulcandidate will be provided with a competitive startuppackage and will be expected to establish a vigorous,externally funded research program and to participatein teaching undergraduate and graduate courses. Forinformation about the Department of Biology and forlinks to the campus and the Bloomington communi-ty, see website: http://www.bio.indiana.edu.
Candidates should send curriculum vitae, a state-ment of research, and representative publications andshould arrange to have three (or more) letters of rec-ommendation sent to: Jim Bever, Population/Community Ecology Search, Department of Biol-ogy, Indiana University, 1001 East Third Street,Bloomington, IN 47405-3700. Review of applica-tions will begin October 20, 2004, and will continueuntil suitable candidates are identified.
Indiana University is an Affirmative Action/Equal Oppor-tunity Employer. Women and minority candidates are encour-aged to apply.
The Department of Chemistry at The University ofToledo, home of the Ohio Macromolecular Crystal-lography Consortium, invites applications or nomina-tions for a tenured or tenure-track FACULTY PO-SITION in macromolecular X-ray crystallography.This appointment will complement existing depart-ment strengths in structural biology and biologicalchemistry, and coincides with a major upgrade of theexisting crystallography laboratory that has added anew high brilliance diffractometer, and a roboticscrystallization and crystal imaging facility. The suc-cessful candidate will have a Ph.D. degree in chemis-try or a related field, will be expected to have or todevelop a vigorous, externally funded research pro-gram, and to have a commitment to excellence inteaching chemistry at both the undergraduate andgraduate level. The University of Toledo offers com-petitive salaries and an excellent benefits package to itsfaculty. Further information on available faculty posi-tions, the new research facilities for chemistry (WolfeHall), and the Instrumentation Center is available atwebsite: http://www.chem.utoledo.edu. Seniorapplicants should send their curriculum vitae and asummary of research accomplishments; junior-levelapplicants should also send a research plan and ar-range for three letters of recommendation to be sentto: Chair, X-ray Crystallography Faculty SearchCommittee, Department of Chemistry MS 602,The University of Toledo, Toledo, OH 43606.Review of applications will begin on October 1, 2004,and continue until a suitable candidate has been iden-tified. The Department encourages applications from minori-ties, women, and persons with disabilities. The University ofToledo is an Affirmative Action/Equal Opportunity Employer,Minorities/Females/Persons with Disabilities/Veterans.
FREELANCE SCIENCE EDITORSTranslations company seeks Editors to work on as-
needed basis. Receive work via computer. Will editdocuments translated from various languages intoEnglish, ensuring scientific accuracy and clarity. Edu-cation in biology, chemistry, or engineering. Editingexperience not required, but need a keen eye for de-tail. Subjects include chemical patents, biotech, med-ical studies, and industrial standards. Send resume viae-mail: [email protected].
RESEARCH GENETICIST (PLANTS)RESEARCH MOLECULAR BIOLOGIST
(PLANTS)GS-440/401-12/13/14
SALARY RANGE: $65,706 to $120,033The U.S. Department of Agriculture, Agricultural
Research Service, in Albany, California, is seeking apermanent, full-time Research Scientist. The success-ful applicant will conduct basic research in plant com-putational biology/plant genomics at the Plant GeneExpression Center, developing an independent pro-gram in plant genome research that enhances analysisand integration of data from the study of maize andother important agricultural genomes. The successfulapplicant will be considered for an ADJUNCT FAC-ULTY POSITION at the Department of Plant andMicrobial Biology, University of California, Berkeley.Candidates should have a Ph.D. degree and an excel-lent publication record. For application directionssee website: http://www.afm.ars.usda.gov/divisions/hrd/index.html, announcement numberARS-X4W-295. Applications must be postmarkedby September 17, 2004. For information about thePlant Gene Expression Center, see our website at:http://www.pgec.usda.gov/ or contact: Dr.Sarah Hake at e-mail: [email protected]. U.S. citizenship is required. USDA/ARS is an EqualOpportunity Employer and Provider.
Roosevelt University is seeking an ASSISTANTPROFESSOR of biology for a tenure-track positionto begin August 2005. The successful candidate willteach major courses in physiology, immunology, andgeneral biology, and supervise undergraduate andMaster’s level students’ research projects and intern-ships. Applicants should have a Ph.D., strong knowl-edge of modern techniques and computational meth-ods in biology, and a demonstrated commitment toteaching and undergraduate research. We especiallyencourage women and minority candidates to apply.Please send a letter of application, curriculum vitae,two-page statement of undergraduate teaching phi-losophy and research interests, and the names, tele-phone numbers, and e-mail addresses of at least threereferences to: Cornelius Watson, Assistant Direc-tor of the School of Science and Mathematics,Roosevelt University, Chicago, IL 60605. Screen-ing will begin on November 15, 2004, and continueuntil the position is filled. Telephone: 312-341-3678; fax: 312-341-4358; e-mail: [email protected]; website: http://www.roosevelt.edu. Roosevelt University is an institution dedicated to socialjustice that serves a diverse population of students with campusesin Chicago’s South Loop suburban Schaumburg.
FACULTY POSITIONCentral Nervous System Drug Delivery/Vascular
BiologyThe Department of Pharmaceutical Sciences at
Texas Tech University Health Sciences Center(TTUHSC) School of Pharmacy at Amarillo has anopening for a tenure-track faculty position at the AS-SISTANT/ASSOCIATE PROFESSOR level tojoin an established group of researchers investigatingbrain drug delivery and vascular biology. Preferencewill be given to applicants with an extramurally fund-ed program. In addition to maintaining their researchprogram, the successful candidate will teach in thebasic science components of the Pharm.D. and Ph.D.curriculum, and mentor graduate students. Startuppackages and laboratory space are competitive. Sub-mit curriculum vitae, a summary of research andteaching interests, and names and addresses of threereferences to: Dr. Margaret Weis, Search Commit-tee Chair, Texas Tech University School of Phar-macy, 1300 Coulter, Amarillo, TX 79106. E-mail:[email protected]; fax: 806-356-4034.TTUHSC is an Equal Opportunity/Affirmative Action In-stitution. Minorities and Women are encouraged to apply.
ASSISTANT OR ASSOCIATE PROFESSORTENURE TRACK
Cardiovascular Science�PharmacologyMedical College of Georgia
We are seeking an individual with outstanding po-tential and accomplishments in cardiovascular researchto complement and extend our current researchstrengths. We have established research programs incardiac, endothelial, and vascular smooth muscle phar-macology, with specific interests in nitric oxide, oxida-tive stress, second messenger signal transductionmechanisms, hypertension, endothelial dysfunction,myocardial disease, diabetes, and cardiovascular ionchannels. We encourage applicants with expertise in allareas of cardiovascular science, particularly in the fac-tors that control cardiovascular dysfunction associatedwith diabetes and heart failure. Physician scientists areencouraged to apply. We offer a generous startuppackage and outstanding facilities are available forelectron microscopy, cell imaging, microarray technol-ogy, genetically modified animals, primate research,and clinical collaborations. The successful applicantwill participate in teaching programs for professionaland graduate students. Please send curriculum vitae,summary of professional and research goals, and thenames and addresses of three references to: Richard E.White, Ph.D., Department of Pharmacology andToxicology, Medical College of Georgia (MCG),Augusta, GA 30912-2300. E-mail: [email protected] and visit the Medical College of Geor-gia homepage (website: http://www.mcg.edu).Application review will begin October 2004. MCG isan Equal Employment Opportunity/Affirmative Action EqualAccess Employer. PO# E000051148.
FACULTY POSITIONCOMMUNITY ECOLOGY
The Department of Biology, Skidmore College, in-vites applications for a tenure-track ASSISTANTPROFESSOR position in community ecology, be-ginning in the fall of 2005. The successful candidatewill complement the Department’s existing strengthsin population biology and will contribute to the envi-ronmental studies major. Applicants must have aPh.D. in biology or a related discipline, teaching ex-perience, a successful independent research program,and a primary interest in teaching undergraduates at aliberal arts and science institution; postdoctoral expe-rience is preferred. Yearly course load will be selectedfrom among a general ecology course for biologymajors, an environmental biology course for environ-mental studies majors, and specialty courses in thecandidate’s area of expertise. Establishment of astrong research program that involves undergraduatesis expected; excellent teaching and research facilitiesand support are available. Send curriculum vitae,statements of teaching and research interests, andthree letters of recommendation to: Corey R.Freeman-Gallant, Chair, Department of Biology,File #SI, Skidmore College, Saratoga Springs, NY12866, Community Ecologist Search. Review ofapplications will begin October 14, 2004.
Skidmore encourages applications from women and men ofdiverse racial, ethnic, and cultural backgrounds.
ASSISTANT PROFESSOR OF BIOLOGYSaint Mary’s College of California invites applicants
for a tenure-track position to begin in the fall of 2005.Candidates’ primary expertise must be in immunolo-gy or a closely related field. Teaching expectations willinclude courses in immunology, cell and molecularbiology, and human physiology. Successful candi-dates must share the College’s commitment to teach-ing excellence in a small liberal arts Catholic setting.An active program of scholarship involving participa-tion by undergraduates will also be expected. Sendcurriculum vitae, teaching and research statement,and three letters of recommendation to: Dr. AllanHansell, Search Committee Chair, Department ofBiology, Saint Mary’s College of California, P.O.Box 4507, Moraga, CA 94575. Review of applica-tions will begin October 15, 2004.
POSITIONS OPEN POSITIONS OPEN POSITIONS OPEN
17 SEPTEMBER 2004 VOL 305 SCIENCE Science Careers www.sciencecareers.org1850
Linus Pauling Institute Prize for Health Research
Call for Nominations
The Linus Pauling Institute Prize for HealthResearch is sponsored by the Linus PaulingInstitute at Oregon State University (http://lpi.oregonstate.edu). The Prize consists of$50,000 and a medal, and is awarded bienni-ally. The LPI functions from the basic premise that an optimum diet and a healthy lifestyle is the key to optimum health. The purpose of the Prize is to recognize innovation and excellence in research relating to the roles of micronutri-ents, vitamins, and phytochemicals in promotinghealth and preventing or treating disease; andthe roles of oxidative/nitrative stress and anti-oxidants in human health and disease. The aim is to stimulate innovative research that enhances our knowledge of the role of diet and lifestyle in the primary and secondary prevention of disease,and the role of oxidative/nitrative stress in the causation of disease.
Procedure: The nominator should submit anomination letter, two supporting letters solic-ited from his/her colleagues, and the candidate’s up-to-date curriculum vitae. The candidate’s research accomplishments in light of the purposeof the Prize should be amply described in the let-ters. The awardee must be present to accept the Prize and present a talk at the “Diet and OptimumHealth” conference organized by LPI in Portland,Oregon, May 18-21, 2005. Nominations should be sent to: Linus Pauling Institute, Attn: Barbara McVicar, Oregon State University, 571 Weniger Hall, Corvallis, OR 97331-6512.Complete nomination materials must be receivedby November 1, 2004.
UNIVERSITY OF TEXAS SOUTHWESTERN MEDICAL CENTER
Faculty Positions in Infectious Diseases
The Division of Infectious Diseases in the Department of Medicine at the University of Texas Southwestern (UTSW) Medical Center at Dallasis seeking new faculty members at the Assistant Professor, Associate Professor, or Professor levels. Faculty will be expected to developindependent and externally funded independent research programsthat focus on understanding the molecular pathogenesis of infectious diseases and/or host defense mechanisms. Preference will be given to applicants performing “cutting-edge” research on medically important pathogens, emerging pathogens, and/or agents of potential biothreat. Excellent opportunities exist for collaborations with faculty members in Infectious Diseases, the Department of Microbiology, and the Center for Immunology at UTSW and with the Regional Center of Excellence (RCE) for Biodefense and Emerging Infectious Diseases. UTSW is anoutstanding scientifi c environment with established strengths in struc-tural biology, biochemistry, molecular biology, genetics, and numerous other areas. Candidates will be expected to contribute to the teaching andresearch training of Infectious Diseases fellows. The position offers an attractive startup package and laboratory space. Candidates should have an M.D. and/or a Ph.D. degree with at least two years of postdoctoral experience and an outstanding publication record.
To apply, submit a C.V., three letters of reference, and a description of research interests to: Dr. Beth Levine, Chief, Division of Infectious Diseases, c/o Renee Talley, UT Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-9113. E-mail: [email protected].
UT Southwestern is an Equal Opportunity/Affi rmative Action Employer.
PROFESSOR OF BIOLOGY, CHEMISTRY, OR PHYSICS, AND DEPARTMENT CHAIRJOINT SCIENCE DEPARTMENTTHE CLAREMONT COLLEGES
Claremont McKenna, Pitzer and Scripps Colleges, selective liberal arts colleges in the Claremont Colleges Consortium, seek an accomplished teacher-scholar to serve as professor and chair of our integrative Joint Science Department (www.jsd.claremont.edu). The successful candidatewill be qualifi ed to hold a senior tenured faculty rank in biology, chemistryor physics. He/she will teach and do productive research in her/his fi eld and lead the Department for a three-year term. Teaching responsibilities will be reduced by 60% to allow for administrative duties. The Departmenthas 25 faculty in life and physical sciences and offers majors in the three disciplines, as well as in a variety of interdisciplinary areas. In addition, the Department serves the needs of nonscience majors with a series of specially designed courses. Faculty are extensively involved in research, particularly with undergraduates. The Department is housed in a single facility opened in 1992 and expanded in 2000, with excellent facilities forresearch and teaching. Adequate startup funds for the new chair’s research will be provided. The Department Chair reports to the Dean of Faculty, develops budgets, manages staffi ng, and provides leadership in assessingdepartmental needs and assisting in fundraising to meet those needs.
Applications will be reviewed beginning September 30, 2004, and continue until the position is fi lled. Please send a letter of application describing your interest in the position, a statement of teachinginterests and philosophy, curriculum vitae, and a statement of research accomplishments and goals, and have three letters of reference sent to: Dr. James Higdon, Professor of Physics, Keck Science Center, 925 N. Mills Ave., Claremont, CA 91711; [email protected].
In a continuing effort to enrich our academic environment and provide equal educational and employment opportunities, The Claremont
Colleges actively encourage applications from women and members of historically underrepresented groups in higher education.
MAYO CLINIC ANGIOGENESIS SYMPOSIUM - October 29-31, 2004Rochester, Minnesota
ATTENTION POSTDOCTORAL FELLOWS, RESIDENTS, and STUDENTS!
REASONABLE FEES ($200, includes food)! Don’t Miss This Opportunity To Register and Submit Abstracts.
Program DirectorsDebabrata Mukhopadhyay, Ph.D., Mayo Clinic
Philip Greipp, M.D., Mayo Clinic
Program Co-ChairpersonsDavid Cheresh, Ph.D., The Scripps Research Institute
Mary Hendrix, Ph.D., Northwestern UniversityRaghu Kalluri, M.D., Beth Israel Deaconess Medical Center
Neil Kay, M.D., Mayo Clinic
Guest FacultyKenneth Anderson, M.D.M. Luisa Iruela-Arispe, Ph.D.Vicki Bautch, Ph.D.Laura Benjamin, Ph.D.Peter Bohlen, Ph.D.Thomas Davis, M.D.Daniel Dumont, Ph.D.Harold Dvorak, M.D.
Jan Kitajewski, Ph.D.Jack Lawler, Ph.D.Charles Little, Ph.D.Donald McDonald, M.D., Ph.D.Suresh Mohla, Ph.D.Nikhil Munshi, M.D.Andras Nagy, Ph.D.Shahin Rafi i, M.D.
Sundaram Ramakrishnan, Ph.D.William Sessa, Ph.D.Mihaela Skobe, Ph.D.Shay Soker, Ph.D.George Yancopoulos, M.D., Ph.D.Alex Adjel, M.D., Ph.D.Vincent S. Rajkumar, M.D.Kalpna Gupta, Ph.D.
and Others…
Abstract deadline extended to: September 24, 2004. CME credit is available to qualifi ed physi-cians. Please see our website for registration, discounted travel, hotel, and abstract information:http://mayoresearch.mayo.edu/mayo/research/angiogenesis.cfm.
AWARDS SYMPOSIA
POSITIONS OPEN
PROFESSOR AND HEADDepartment of Chemistry and Molecular Biology
Nominations and applications are invited for theposition of Professor and Head of the Department ofChemistry and Molecular Biology at North DakotaState University (NDSU). All areas of these disci-plines will be considered. The appointment begins onor about May 2005. Applicants should have a Doc-torate in chemistry, biochemistry, or related field, andan outstanding record in research and undergradu-ate/graduate teaching appropriate to appointment atthe rank of PROFESSOR with tenure; leadershipand administrative skills; have an extramurally fundednationally competitive research program and the abil-ity to implement it at NDSU; demonstrated ability towork effectively with colleagues in an academic set-ting; and have effective oral and written communica-tion skills. The Department of Chemistry and Molec-ular Biology (website: http://www.chem.nd-su.nodak.edu) is a Ph.D.-granting unit of the Col-lege of Science and Mathematics, which enrolls 2,000of the University’s 12,000 students. The Departmenthas 18 faculty, with research expenditures averaging$3 million per year. Several lecturers assist with teach-ing and Ph.D.-level research specialists staff all themajor instrumentation facilities (molecular modeling,nuclear magnetic resonance, mass spectrometry, X-ray crystallography). The Department averages 90 un-dergraduate majors, 35 graduate students, and 20postdoctoral researchers. The University is expandingits research enterprise, particularly through its newResearch and Technology Park, graduate fellowships,and research centers. The Department is playing anintegral role in this growth. NDSU is located in Fargo(website: http://ci.fargo.nd.us), the largest city inNorth Dakota, which is often cited for its high qualityof life. Candidates should submit a letter of applica-tion, curriculum vitae outlining qualifications in re-search, teaching, and leadership, a discussion of theresearch program that would be conducted at NDSU,and contact information for five references to: Pro-fessor Gregory R. Cook, North Dakota State Uni-versity, Department of Chemistry and MolecularBiology, P.O. Box 5516, Fargo, ND 58105-5516.E-mail: [email protected]. Review ofapplications will begin on November 15, 2004, andcontinue until the position is filled. NDSU is an EqualOpportunity Institution.
DEPARTMENT OF HEALTH AND HUMANSERVICES
National Institutes of HealthNational Institute of Diabetes and Digestive and
Kidney DiseasesLaboratory of Molecular Biology
National Institute of Diabetes and Digestive andKidney Diseases, National Institutes of Health(NIH), is recruiting for a STAFF SCIENTIST po-sition in computational protein crystallography. Theposition entails responsibility for the system manage-ment of a cluster of computers that serves the compu-tational needs of three protein crystallographic groupsconsisting of about 12 scientists, as well as engaging inthe research program of the Section on MolecularStructure, which involves HIV and immunology.Qualifications should include experience with proteincrystallography and computer system management,including operating systems UNIX and LINUX. Sal-ary commensurate with experience and a full CivilService package of benefits (including retirement,health, life and long-term care insurance, thrift sav-ings plan participation, etc.) is available. Applications,together with three references, should be addressedto:
David R. DaviesBuilding 5, Room 338
NIH, Department of Health and Human Services5 Center Drive, MSC 0560Bethesda, MD 20892-0560
E-mail: [email protected] deadline for applications is November 14,
2004. DHHS/NIH are Equal Opportunity Employers.
ASSISTANT PROFESSOR of Biochemistry/Molecular Biology: The Department of BiologicalSciences at Michigan Technological University in-vites applications for a tenure-track position (fall2005) in biochemistry and molecular biology. Thesuccessful applicant must have postdoctoral experi-ence, a demonstrated expertise in the use of currentbiochemical and molecular techniques, and will beexpected to establish an extramurally funded re-search program, supervise graduate students, andinteract with departmental faculty in research areasranging from microbial to plant/animal systems.The position requires a commitment to undergrad-uate and graduate instruction in biochemistry andmolecular biology. Additional information can beobtained at the departmental website: http://ww-w.bio.mtu.edu/. Applicants should submit curric-ulum vitae, including a statement of research inter-ests, teaching philosophy, and three letters of rec-ommendation to: Chair, Search Committee, De-partment of Biological Sciences, MichiganTechnological University, 1400 TownsendDrive, Houghton, MI 49931. Telephone: 906-487-2025; e-mail: [email protected] of applications will begin on October 29,2004, and will continue until the position is filled.Michigan Technological University is an Equal OpportunityEducational Institution/Equal Opportunity Employer.
Tufts University, Department of Biomedical En-gineering, is seeking candidates for a faculty appoint-ment at the ASSISTANT, ASSOCIATE, or FULLPROFESSOR level. Rank will be determined by ex-perience and accomplishments. Preference will be giv-en to candidates whose research interests involve re-generative medicine systems, and complement theDepartment’s strengths in biomedical imaging andinstrumentation. The successful candidate will join anactive Ph.D.-granting department and must demon-strate the potential to develop an outstanding, inter-nationally recognized research program, excel inteaching, and develop strong inter-school collabora-tions. Teaching responsibilities include graduate andundergraduate courses. A Doctorate is required andpostdoctoral experience is desirable. Additional infor-mation about the Department can be found at web-site: http://ase.tufts.edu/biomedical/. Interestedapplicants should send curriculum vitae, cover letter,research plan, and names of three references to: Fac-ulty Search Committee, Department of Biomedi-cal Engineering, Tufts University, 4 Colby Street,Medford, MA 02155. Evaluation of candidates willbegin at the end of October 2004 and continue untilthe position is filled. Tufts University is an AffirmativeAction/Equal Opportunity Employer. We are committed toincreasing the diversity of our faculty. Applications from womenand members of underrepresented groups are strongly encouraged.
INVERTEBRATE ZOOLOGISTThe Department of Biology, College of Charleston,
invites applications for a tenure-track position in in-vertebrate zoology at the ASSISTANT PROFES-SOR level. Candidates must possess a Ph.D., a strongcommitment to teaching, and an active research pro-gram with the potential for undergraduate involve-ment. Teaching responsibilities include a lecture andlaboratory course in invertebrate zoology. We are par-ticularly interested in applicants who break disciplin-ary boundaries (e.g., biomechanics, larval biology,marine genomics). The College of Charleston is apublic liberal arts and sciences institution of 10,000students. The College’s primary aims are teaching andresearch excellence. In addition to its undergraduateprograms, the Department offers M.S. degrees in ma-rine biology and environmental studies. Informationabout the Biology Department can be found at web-site: http://www.cofc.edu/��biology/. Applicantsshould submit curriculum vitae, statements of teach-ing philosophy and research interests, reprints of re-cent publications, and three letters of reference by 1November 2004 to: Chair, Department of Biology,College of Charleston, Charleston, SC 29424. TheCollege of Charleston is an Equal Opportunity/AffirmativeAction Employer and encourages the applications of qualifiedwomen and minorities.
TENURE-TRACK POSITIONSBiology Department
The Department of Biology invites applications fortenure-track positions in the following areas to en-hance rapidly expanding programs.
(1) ASSISTANT/ASSOCIATE PROFESSOR.Freshwater wetland ecology within a Ph.D. programin aquatic resources. We seek a candidate broadlytrained with interdisciplinary abilities and experiencethat bridge basic and applied scientific and manage-ment problems at the community, ecosystem, or land-scape scales. Quantitative and spatial analysis skills aredesirable. Note #2005-24 on application.
(2) ASSISTANT PROFESSOR. Wildlife ecolo-gy. We seek a candidate with expertise in mammalianor avian ecology, especially related to distance sam-pling of wildlife populations and geographic informa-tion system application to such data. Note #2005-25on application.
Individuals are to establish extramurally funded re-search programs, train graduate students, and teach atthe undergraduate and graduate levels. Qualified ap-plicants are invited to submit curriculum vitae, copiesof up to five publications, statements of teaching andresearch interests, and a list of four references includ-ing telephone numbers and e-mail addresses to: Jo-seph Koke, Interim Chair, Biology Department,Texas State University�San Marcos, San Marcos,TX 78666. Review of applications begins on 30 Oc-tober 2004 and continues until successful candidatesare found. San Marcos is located in the scenic TexasHill Country midway between Austin and San Anto-nio. Texas State University owns and manages theheadwaters of the spring-fed San Marcos River andassociated ecosystems. For additional informationabout our Department, see website: http://www.bio.txstate.edu. Texas State University is an Equal Op-portunity Employer.
Department of Biology. DePauw University.MICROBIOLOGIST/MOLECULAR BIOLO-GIST. Tenure-track position beginning August2005. Rank and salary commensurate with experi-ence. Ph.D. preferred, all but dissertation required.Commitment to undergraduate teaching in liberalarts setting essential. Teaching responsibilities in-clude: laboratory courses in microbiology, molecularbiology, and cell biology. Successful candidate will beexpected to conduct summer research projects withundergraduate students. For information about theDepartment, visit website: http://www.depauw.edu/acad/biology/. DePauw has exceptional pro-grams for supporting its faculty members, including apre-tenure leave and funding for professional and cur-riculum development activities (see website: http://www.depauw.edu/admin/acadaffairs/facdev.htm). Submit letter of application, curriculum vitae,three letters of recommendation, transcripts, state-ments of teaching interests and philosophy, researchinterests, and evidence of teaching effectiveness to:Henning Schneider, Search Chair, Department ofBiology, DePauw University, Greencastle, IN46135. Review of applications begins October 1,2004, and continues until position is filled. DePauwUniversity is an Affirmative Action/Equal Opportunity Em-ployer. Women and members of underrepresented groups areencouraged to apply.
ANNOUNCEMENTS
STAGLIN FAMILY MUSIC FESTIVALSCHIZOPHRENIA RESEARCH AWARD
NARSADNational Alliance for Research on Schizophrenia
and Depression (NARSAD) announces a new Schizo-phrenia Research Award of $250,000 for one investi-gator with M.D., Ph.D., or doctoral degree and post-doctoral training applicable to schizophrenia, at As-sistant or Associate Professor level. Nomination fromdean, chair, or head of scientific program from em-ploying university required. Deadline: December 3,2004. Start date: July 1, 2005. See website: http://www.narsad.org or telephone: 516-829-5576.
POSITIONS OPEN POSITIONS OPEN POSITIONS OPEN
17 SEPTEMBER 2004 VOL 305 SCIENCE Science Careers www.sciencecareers.org1852
List your event in Science’s2005 Events Calendar
For full details contact:U.S. .................................................... Daryl Andersonphone ..................................................202-326-6543e-mail .................................... [email protected]
Europe/International .................... Emilie Stottphone ................................. +44 (0) 1223 326 527e-mail ........................ [email protected]
• American Society forCell Biology (ASCB)4–8 December 2004Washington, DC
• AmericanGeophysical Union13–17 DecemberSan Francisco, CA
• AAAS Annual Meeting17–21 February 2005Washington, DC
• Experimental Biology2–6 April 2005San Diego, CA
BONUS DISTRIBUTIONS
OCTOBER 1DEADLINE
FREE LISTINGAll organizations are eligiblefor one FREE listing. Go towww.sciencemeetings.orgto submit your listing.
ADVERTISING WITHCALENDAR LISTINGSYou may choose to run a printad in the special banneredMeetings & Announcementssection following the pulloutEvents Calendar. With your adplacement, you receive bonuscalendar listings.
Call for Innovative Ideas to Advance Prevention, Treatment and Cure of Type 1 Diabetes
Background: The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health (NIH), leads a Special Statu-tory Funding Program ($150 million/year) for Type 1 Diabetes Research, on behalf of the Secretary of the Department of Health and Human Services. The special program supports research to pursue compelling opportunities in type 1 diabetes research (more information on the program can be found at: http://www.niddk.nih.gov/fund/diabetesspecialfunds/). The program is framed around six broad, scientifi c goals:
Goal I: Identify the Genetic and Environmental Causes of Type 1 Diabetes Goal II: Prevent or Reverse Type 1 DiabetesGoal III: Develop Cell Replacement TherapyGoal IV: Prevent or Reduce HypoglycemiaGoal V: Prevent or Reduce the Complications of Type 1 DiabetesGoal VI: Attract New Talent and Apply New Technologies to Research on Type 1 Diabetes
Call to Identify New and Emerging Scientifi c Opportunities: The NIDDK invites submission of innovative ideas and approaches toward accelerating progress and overcoming research barriers to the prevention, treatment and cure of type 1 diabetes and its complications. There is signifi cant fl exibility in the use of these funds; opportunities could be pursued through solicitations for traditional research grants or through mechanisms to support larger col-laborative efforts. Suggestions should focus on identifying the opportunity and approaches, technology and expertise useful for its development rather than on a funding instrument or solicitation design. Suggestions that will involve creative scientists and scientifi c communities not currently working on type 1 diabetes, and with the potential to contribute to prevention, treatment and cure of type 1 diabetes, are particularly encouraged.
Use of Submissions: Submissions will be considered by NIH and CDC scientists and by an advisory panel to be convened by NIDDK as part of the pro-cess guiding use of the Special Statutory Funding Program for Type 1 Diabetes Research. Therefore, submissions will not be confi dential, although they may be anonymous. New research solicitations and/or program enhancements may be developed to address ideas submitted; however, there is no funding associated with this announcement.
Submitting an idea: Please describe your suggested opportunity or approach including: (1) how it could potentially have a major, positive impact on one or more of the six goals above, and/or (2) the current research barriers it could help overcome. You are welcome to submit more than one idea, but please limit the description of each to one page in length. For hard-copy submission, please mail or FAX your submission(s) to: Topics Regarding Type 1 Diabetes Research Opportunities, NIH/NIDDK/OSPPA, 9000 Rockville Pike, Building 31, Room 9A05, Bethesda, MD 20892-2560, Attn.: Mary C. Hanlon, Ph.D.; Phone: 301-496-6623; FAX: 301-480-6741. For electronic submissions, please visit the following website: http://www.niddk.nih.gov/forms/T1D-Opportunity.htm.
Deadline: For full consideration, submissions are due by Friday, October 22, 2004.
National Institute ofDiabetes & Digestive &
Kidney Diseases
ME
ET
ING
S a
nd
AN
NO
UN
CE
ME
NT
S
17 SEPTEMBER 2004 VOL 305 SCIENCE www.sciencemag.org1854
MARKETPLACE MARKETPLACEMARKETPLACE
1.415.883.8400www.biosearchtech.com
B I O S E A RC HT E C H N OLO G I E SChemistry for Genomics and Proteomics
SM
SO U RC I N G PCR PRO B E S?ON LY BI O S E A RC H
C U S TO M S Y N T H E S I Z E S T H E M A L L!
BLAC K HO L E SC O R PI O N S®
DI R E C T AM P L I F LU O R S™
MO L E C U LA R BE AC O N S™
TAQMA N™ PRO B E S
PU L S A R™ LI G H TCYC L E R™ PRO B E S
The World of Science Online
www.scienceonline.org
SAGE KEE-Marketplace
ScienceCareers.orgScience’s Next Wave
Science NOWSTKE
� � � � � � � � � � � � �
� � � � � � � � � ����� ���������_��������� � �`� � ���
_�� �z{�`�� �`� ]`|���`���|} ]`��}���� ��� �� ����� �� � � " � � � � # " $ � % # # #
��� � ��� � � � � � se rv ice^��� � � � � �
����������������������� �
�������������������������������������������������������
����������
������������������ ���
� ���� �
� ��
���� ��
�� ������������� �� �������� ��� � ������������ � ���� �� ������
����� ��� �� � ��� ����� ����� � ��� ��������� ��M �
�������
������� ���� ������� �� ��� � ��������
� �� ��� ������ � � �� ���� ��
d e s g n e rBe a c o n 3
Molecular beaconsTaqMan® probes
FRET probesFor real time QPCR
GCAT
G
GCAT
G
C
A
T
TGCA
ATGC
GCA
G
C
A
T
G
CT
GCA
GCAT
High throughput DNA sequencingGene synthesis $2/bp any sizeProtein expression & purificationYeast 2 hybrid/phage displaying
www.mclab.com, 888-625-2288
North America: 800-234-5362 • email: [email protected]
Now available at the 0.025 µmole scale!
Yield - 15-30 µgRP-HPLC purified
QC by MALDI-TOF Mass Spec. and UV analysis Ship in 2mL amber vial to protect dye integrity
Shipment in 3 - 5 days
U.S. Pricing starts at $110. See our website for details and special offers.
ISO 9001:2000 Certified
www.sigma-genosys.com
®
��� ������ ��� � ���� ���� �� �����
��� ���� ����� � � �� ������ ��� ����� ����������� ���� ��� �� �������
������������������������
����������� ������ ��
888-267-4436 • WWW.ORIGENE.COM
IS A COPY COMPROMISING THEVALUE OF YOUR RESEARCH?
TrueCloneTM CollectionOver 22,000 Authentic Full-Length Human cDNA Clones
10,000 priced under $200!
NOW $50 PER PEPTIDE!
• MALDI-TOF Mass Spec on all peptides• Traces supplied to customer
• Amount: 0.5-2mg• Length 6-20mers• Modifications available• Average purity: ~70% (based on 15mer)• Peptides supplied in 96-well format (tubes)• Delivery: ~7 working daysMinimum order size is 48 peptides
North America and Canada • 1-800-234-5362Email: [email protected]
www.sigma-genosys.com/MP
®
Guaranteed Silencing with Silencer™ Validatedand Pre-Designed siRNAs
The most extensively verified design algorithm – tested on >1100 siRNAs.Designed for maximum potency and specificity.
Point. Click. Silence.
Find effective siRNAs to >34,000 human, mouse, and rattargets in mere minutes at www.ambion.com/prod/siRNA
Silencer Validated siRNAs• Functionally tested in cells
• Every one guaranteed to reduce targetmRNA levels 70% or more
• Available to hundreds of human targets
Silencer Pre-designed siRNAs• Guaranteed – at least two siRNAs
guaranteed to reduce target mRNA levels by 70% or more when three purchased
• Available for >34,000 human, mouse, and rat targets