hindu sci tech may 2016 xaam.in

8/16/2019 Hindu Sci Tech May 2016 Xaam.in

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Tattoos on the Moon

» Nasa research reveals the source of swirling dark and light patterns on themoon as due to brawny electricpotentials that could deflect solar windparticles.

FILE PHOTO

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EducationPlus02 THE HINDU | MONDAY | MAY2, 2016- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

NOIDA/DELHI

SNAPSHOTS

Pesticide sprays link tohealth

» Using aeroplanes to spray anti-mosquito pesticides may increase therisk of autism spectrum disorder anddevelopmental delays among children,scientists have found.

Care for your gut

» Your food intake affects yourintestinal bacteria and, in turn, yourhealth. Researchers report in Science that yoghurt or buttermilk increasestheir diversity while whole milk or high-calorie diet decreases it.

PHOTO: SHIVAJI RAO

Unique rocky comet fromOort cloud

» Astronomers report in Science Advanceson finding a rocky likely madeof inner Solar System material from thetime of Earth’s formation, preserved inthe Oort Cloud far from the Sun forbillions of years.

PHOTO: K. MEECH (IFA/UH)/CFHT/ESO

cant association,” said HamdiMbarek from Vrije Universi-teit in Amsterdam, who ledthe study, in an email to me.

Mothers who had one spe-cific variant of the FSHB genewere more likely to have giv-en birth to non-identicaltwins. This variant is linked toincreased production of folli-cle stimulating hormone(FSH), leading to more thanone egg maturing and conse-quently multiple ovulation.The second, SMAD3, likelyaffects how the ovaries re-spond to FSH. Mothers of non-identical twins were sig-nificantly more likely to carrya variant of SMAD3 whichmakes her ovaries more sen-sitive to the same amount of FSH.

Lessons from past

failuresEfforts to characterise the

genes that contribute to non-identical twinning in humanshad been largely unsuccessfuluntil this study. But these fail-ures did not go in vain. “Theytaught us that non-identicaltwinning in humans is a poly-genic trait and that muchmore powerful genome-wideassociation studies (like thisone) are required to find thegenes which may offer in-sights for new treatments,”said Mbarek.

He added that rigorous se-lection of their cohort moth-ers to make sure none re-ceived any kind of fertilitytreatment was also a crucialfactor for enabling theseresults.

The scientists stress thattheir findings are probablyjust the beginning. “There is avery clear suggestion and in-dication that more loci arecontributing,” said co-authorDorret Boomsma in a pressrelease.

Knowing one’s predisposi-tion to multiple births can bevery useful in the light of riskslike premature birth associat-ed with twinning. Mbarekadded that future studies intoSMAD3, the totally new can-didate for twinning, may offera novel avenue for fertilitytreatments, particularly inwomen who poorly respondto ovarian stimulation and al-so help in prevention of pre-mature ovarian ageing.

(Nandita Jayaraj is a freelancer based in Bengaluru.)

Two genes that affect awoman’s likelihood of giving birth to twinshave been identifiedin a new study pub-

lished in American Journal of Human Genetics . This couldhave implications for fertilityresearch and help predicthow women will respond totreatments for infertility.

Identical, or monozygotic(MZ), twins occur at a fairlystable frequency of 3 to 4 per1,000 births all around theworld. In contrast, the occur-rence of fraternal, or dizygot-ic (DZ) twins (non-identicaltwins) varies wildly acrossdifferent kinds of populations— only 6 per 1,000 in Asia but40 per 1,000 in Africa. Oldermothers are four times morelikely to have non-identicaltwins than younger ones; tall-er, heavier women whosmoke and have family histo-ry of twinning are also report-edly more prone to havingfraternal twins. All of thislends to the long-held suspi-cion that there exist geneticfactors that affect a woman’ssusceptibility to give birth tofraternal twins.

Usually, ovulation involvesthe maturation and release of exactly one egg, called the“single dominant follicle.”This chosen egg, if fertilisedby a sperm cell, can lead to apregnancy. The result of thisis a fused cell called the zy-gote which then develops intoan embryo. Very rarely, thezygote divides early on intotwo and each one develops in-to an individual embryo, end-ing up in identical twins. Inthe case of non-identical orfraternal twins, an extra eggcell is released during ovula-tion, opening the possibilityof both getting fertilised bytwo different sperms and theformation of two non-identi-cal embryos.

Before they arrived at thetwo genes, the scientistscombed through the entiregenomes of 1,980 mothers of non-identical twins and 12,953control subjects (motherswith no non-identical twins).They found 30 spots thatseemed to be linked withtwinning and kept narrowingdown. “Two genetic variants,one near FSHB gene and thesecond one in SMAD3 geneshowed a statistically signifi-

The genetics behindfraternal twinningNANDITA JAYARAJ

An extra egg cell is released during ovulation, fertilised bytwo different sperms, forming two embryos. PHOTO: REUTERS

The nuclear industrywould like to forgetApril 26, 1986, the daythe worst nuclear di-saster hit the world.

Ironically, the Chernobyl ac-cident occurred when an ex-periment to improve the re-actor safety system wentterribly wrong. The oper-ators wanted to find outwhether an electrical systemthey made by using the kinet-ic energy of the slowing tur-bo-generator, could provideenough electrical power tooperate the emergencyequipment and the core cool-ing water circulating pumpsuntil the diesel emergencypower supply kicks in.

Writing in The Guardian on April1, 2016 Dr David Rob-ert Grimes, a scientist at Ox-

ford University, aptly notedthat “the mixture of flaweddesign, disabled redundan-

cies and a tragic disregard forexperimental protocol allfeature heavily in the blue-print of the disaster.”

A massive steam explosionblew the 1,000-ton top steelcase through the roof of thereactor building. A secondexplosion threw out burningfragments of nuclear fuel andgraphite starting fires at fivelocations on the roof made of bitumen!

The unprepared and un-protected firemen becamethe first victims of the acci-dent. Investigators estimatedthat about six tonnes of ura-nium dioxide fuel and solidfission products includingmany radio-nuclidesescaped.

Health effects

The authentic report of theUnited Nations ScientificCommittee on the Effects of

Atomic Radiation (UN-SCEAR-2008) published in2011 stated that 28 out of 134heavily exposed plant staff and emergency workers dieddue to radiation exposure.Further 19 of the survivorsdied by 2006. They died dueto various reasons, usuallynot associated with radiationexposure.

“Among the severalhundred thousands of recov-ery workers, apart from an in-dication for an increase in theincidence of leukemia andcataracts among those whoreceived higher doses, thereis no evidence of health ef-fects attributable to radiationexposure,” UNSCEAR noted.

Since authorities did notinitiate prompt countermea-sures against contamination

of milk with iodine 131, somemembers of the general pub-lic received large doses to

their thyroid; this led to asubstantial fraction of themore than 6,000 thyroid can-cers observed to date amongpeople who were childrenand adolescents in April 1986(15 of them died by 2005).

“To date, there has been nopersuasive evidence of anyother health effect in the gen-eral population that can beattributed to radiation expo-sure,” UNSCEAR concluded.In “NucNet Chernobyl FactFile,” NucNet, a global nucle-ar news agency updated thegrisly details of the disasterthis month.

Authorities evacuatedabout 45,000 inhabitants of Pripyat, the nearby town, onApril 27, never to return; thetown remains how it was left.Later they resettled 210,000

people into less contaminat-ed areas, The accident result-ed in the radioactive contam-

ination of 18,000 squarekilometre of agriculturalland, of which people couldno longer farm 2,640 squarekilometre.

Present status

International Atomic En-ergy Agency (IAEA) notedthat “since 1986, radiation

levels in the environmenthave fallen by a factor of sev-eral hundred, due to naturalprocesses and counter-mea-sures and most of the landcontaminated with radio-nu-clides has been made safe

and returned to economic ac-tivity.” Except in areas veryclose to the stricken reactor,

increase in doses were low,often within natural back-ground radiation present

everywhere.About 2,500 workers are

assembling at site a humon-gous 36,000-ton new con-tainment shell (cost $2.45 bil-lion) 350-foot high and500-foot long with a designlife of 100 years. This marvel-lous piece of engineering willbe slid over the stricken reac-tor and the old shelter(sarcophagus).

The Chernobyl accidentforced Russia to eliminatethe deficiencies that causedthe accident in 15 similar re-actors. There are no such de-ficient reactors operating inany country.

A study led by Prof. J. T.Smith, University of Port-smouth, U.K. has revealedabundant wild life popula-tions at Chernobyl (Current Biology,October 5, 2015).

“Chernobyl led to a leap

forward in global coopera-tion on nuclear safety. Coun-tries with nuclear power be-

gan sharing information andexperience in a way they nev-er had before. The IAEA’s

mandate on nuclear safetywas enhanced. IAEA SafetyStandards were expanded,”Mr. Yukiya Amano, the Di-rector General, IAEA statedon April 26.

He listed other notable de-velopments: IAEA adoptedimportant international legalinstruments including theConvention on Nuclear Safe-ty; the agency set up an inter-national coordinated re-sponse system, with theIAEA's Incident and Emer-gency Centre at its heart andan IAEA peer-review systemwhich involves the deploy-ment of international teamsof experts to advise countrieson the operational safety of their nuclear reactors or theeffectiveness of their regula-tory system.

K.S. PARTHASARATHY [email protected]

(The writer is a formerSecretary of the Atomic Energy

Regulatory Board.)

Never again another Chernobyl

A view of the sarcophagus that covers the destroyedreactor at the Chernobyl nuclear power plant. PHOTO: REUTERS

Researchers recentlyspotted 101 species of spiders belonging to65 genera fromChinnar Wildlife

Sanctuary in Idukki, Kerala,when documenting spiderdiversity in the Sanctuary.The spider population fromthe sanctuary accounted for6.98 per cent of the Indianspider species.

Lycosidae, better known aswolf spiders and withexcellent eyesight and agilemovements, were thedominant species in thesanctuary. The researchersencountered multiple webcast in the sanctuary andspotted as many as 10 speciesof Araneidae. These orb-weaver spiders cast theircarefully knitted web ingardens, fields, and forestsand wait for the prey to walkin. The documentation,which was carried out byC.K. Adarsh and P.O Nameerof the Centre for WildlifeSciences of the College of

Forestry, Kerala AgriculturalUniversity, Kerala, waspublished in the Journal of Threatened Taxa.

The spiders were surveyedin bushes, tree trunks, ferns,forest floor, foliage andgrasslands and werehandpicked fordocumentation.

Two endemic genera of

Indian spiders —Annandaliella andNeoheterophrictus — wereidentified during the study.Also, seven feeding guilds of spiders namely orb-weavers,stalkers, ground runners,foliage runners, sheet-webbuilders, space-web builders,and ambushers wereidentified. The report of

Latrodectus hasselti fromChinnar is the first record of the species from Kerala.There are only very fewreports on the occurrence of L. hasselti in other parts of India.

Spiders perform importantecological services byfunctioning as predators innature. They feed on otherinsects and even smallvertebrates. The loss of spiders could lead toecosystem imbalances. Littlehas been understood aboutthe spiders of India,especially that of theWestern Ghats, they pointedout.

The world of spiders isoften shrouded in mystery,and much misunderstandinghas been woven aroundthem. There are popularmisconceptions that allspiders are poisonouscreatures. But, in reality, avery few spiders arepoisonous and harmful tohuman beings, theresearchers pointed out,quoting earlier studies.

101 species of spiders found in Chinnar Wildlife SanctuaryK. S. SUDHI

One of the spiders, known as Gea subarmata, found atChinnar. PHOTO: SPECIAL ARRANGEMENT

ago. A fully grown Rapetosau- rus could measure about 15metres in length, which is abouttwo metres longer than a Volvobus. The generic name Rapeto- saurus itself stands for “giantlizard,” suggestive of the factthat it was among the largest di-nosaurs that walked the earth.While paleontologists knew theshape and size of this dinosaurfrom observations of skeletal re-mains, until recently, the early

life of these so-called titano-saurs has remained a mystery.

“We have lots of adult, sub-adult, and juvenile Rapetosau- rus bones, and these tiny speci-mens literally look like littleminiatures of the bigger bonesin our sample. We could tellright away that the skeleton wasfrom Rapetosaurus, on the basisof the shapes of bones and thepositions of muscle scars...it wasjust from a baby, only 11 per cent

the size of the biggest knownspecimen,” she says.

Using bone histology and x-ray computer tomography, theresearchers were able to under-stand the dinosaur’s growth pat-tern. From the compactness of the bones, the researchers de-duced that the bones likely re-tained their shape as the youngone grew into the adult. Thusthe young ones resembled theadults to a very close degree, un-like in the case of other dino-saurs like theropods and ornith-ischians. The authors furtherpropose that the young onesmust have been independent ata very early age.

Lines of evidenceDr Curry Rogers explains,

“We used three lines of evidenceto support this hypothesis [thatthe young ones were preco-ciously independent]: (1) boneproportions stay the samethroughout life, as in modernprecocial animals; (2) under themicroscope, bones show evi-dence of remodeling, which in-dicates that bones are beingstressed during locomotion, andneed to repair themselves al-ready — this is not seen in otherbaby dinosaurs (like Maiasaura,a duck-billed dinosaur; orTroo- don, a theropod dinosaur); and(3) we looked carefully at thepreserved calcified cartilages atthe ends of long bones — theseprovide a clue about how bonesgrowth in length, and theirthickness in baby Rapetosaurus was very similar to the observedthicknesses in modern preco-cial birds.” These led the au-thors to propose that R. krausei must have been independent of parental care even at very earlystages in their development.

Starting from a reasona-ble size of about 3.5 kg atbirth, a specimen of thedinosaur Rapetosaurus krausei shot up to about

40 kg in just about 39-77 days,when it succumbed to starva-tion. Kristina Curry Rogersfrom Macalester College, U.S.,and collaborators, who werestudying the fossil remains of ayoung one of this species, de-duced that the juveniles closelyresembled the adult in shape.This meant that the young oneswere quite independent at anearly age unlike other species

where young ones enjoyed pa-rental care till they were able tofend for themselves. The resultswere published recently in thejournalScience.

Identifying the fossilsThe fossils of these titano-

saurs, so called for their hugesize, were originally collectedduring the researchers’ fieldseasons in Madagascar, butwere not “discovered” until theyhad been prepared in the lab,and placed within drawersalong with unidentified fossilsof smaller animals from thesame geological formation. “Iwas working in those drawers insearch of bones for another re-search project about growth inthose reptiles, and began find-ing so many tiny titanosaurbones,” writes Dr Curry Rogersin an email to this correspond-ent. In fact, in 2001, along withCatherine Forster, it was DrCurry Rogers who gave this di-nosaur its name.

R. krausei is a dinosaur thatused to inhabit the Madagascarislands about 70 million years

Bone histology and x-ray computer tomography helped study its growth pattern.

SHUBASHREE DESIKAN

Even as an infant the rapetosaurus looks very similar to a full-grown adult. PHOTO: RAUL MARTIN, KRISTINA CURRY ROGERS

Independence comes early

for Rapetosaurus dinosaur

PHOTO: AP


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EducationPlus02 THE HINDU | MONDAY |MAY 9, 2016- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

NOIDA/DELHI

SNAPSHOTS

Decline of dinosaurs

» A study published in Proceedngs of National Academy of Sciences finds thatdinosaurs were in decline long beforetheir final extinction 66 milli on yearsago. The reason was the failure toreplace extinct species with new ones.

Seeded by ducks

» In Europe alone, dabbling ducks maydisperse more than five million seedsdaily, a study of seeds ingested by 7species of migratory, dabbling ducks,from more than 400 plant species,revealed.

A test on galaxies

» Astronomers have estimated the

pressure of interstellar gas in nearbygalaxies, the Small and Large MagellanicClouds and found it to be higher than inthe Milky Way. This can help compareother galaxies with the Milky Way.

Garden lizards may dream

» Slow wave and rapid eye movementpatterns of brain sleep were thought tobe restricted to birds and mammals.Now, brain recordings of lizards pushesback these patterns at least to amniotes,

according to work published in Science.

Anear-invisible silica

gel that would serve asa thermal barrier incryogenic fuel tanks,boot soles and sun

films may sound like a magicalproduct straight from a sci-fi.

But it’s a tangible reality thatresearchers of the Indian SpaceResearch Organization at itsVikram Sarabhai Space Centre(VSSC), Thiruvananthapuram,have made possible.

The yet to be christenedproduct, the hydrophobic silicaaero gel as it is known now, issupposed to have low thermalconductivity and density andhigh specific surface area andcan be applied on any surface.

With its “exotic properties,”

silica aero gels are attractivecandidates for many uniquethermal, optical, acoustic, cata-lytic and chemical applicationsand are best known for their“super-insulating property.”

Silica aero gels can be madein chunks (granular), beads,powder and tape or sheet form,and may be used as the applica-tion demands, according toVSSC.

As air fills the gel up to 95 percent of its size, it comes as superlightweight material. The airmolecules trapped inside thegel would act as insulators, andits heat conductivity is close tozero. They could be used forcoating the windows of housesand vehicles as they would let in95 per cent of the light that fallson the surface and fully deflectthe heat.

“The researchers stumbledupon the exotic properties of the gel during their search for asuper thermal insulator for thecryogenic fuel tanks of rockets.The temperature on the surfaceof the rockets is likely to be be-tween 300 and 400 degree Cel-sius during its flight, and the

cryogenic fuel needs to be insu-lated. Thus, the gel was devel-oped,” explained K. Sivan, di-rector, VSSC.

As the gel acts as a thermalbarrier, it could be used as a pro-tective component of clothesand boots of solders stationedin extremely cold regions suchas Siachen and Kargil. Theweight of military clothes couldbe brought down to ordinarydresses after applying the gelover it thus giving the much re-quired freedom of movementfor the soldiers. To coat a jacketmay require around 500 gramsof gel. “Discussions are on withsome textile developers for thedesign of cloths by applying gelover it,” said Dr. Sivan.

“Besides apparel for soldiers,the gel could also be used forheavy duty dresses used by re-

searchers working in Arctic/Antarctic expeditions. For insu-lating cryogenic fuel tanks, 2.8kg of gel is required. It needs tobe produced in large quantitiesfor commercial use and discus-sions are on with some entre-preneurs,” he explained.

“ISRO has offered the know-how of the technology to suita-ble entrepreneurs in India andthe benefits from the transfer of technology would go to thecountry,” he said.

The other applications of thematerial include acoustic insu-lations, building and pipelineinsulation and window facadesas translucent panels which al-low natural light but not heat forhot areas where air condition-ers are and trapping heat in coldplaces.

It would also be used for con-trolling oil spills and vibration.Other applications includeacoustic damping materials andinsulation in refrigerators, fill-ers or additives in paints, sea-lants, adhesives, cement, coat-ings, foams, and for increasingthe heat resistance of the mate-rial, according to VSSC sources.

Exotic heat-resistant gel:a spinoff from ISRO

K.S. SUDHI

Even as Exomars 2016 , the mars mission launched jointlyby Russia and Europe, is well on its course towards thered planet, the second mission, planned for 2018 has suf-fered a delay. It will now be launched in 2020 instead, ac-cording to a release posted in the European Space Agen-cy's website.

Like the first mission, the second Exomars missionwill also be launched from Baikonur in Kazakhstan withthe help of a Proton rocket. It involves a Russian-led sur-face platform and a European-led rover.

Though efforts were made to reduce delays and launchthe second mission as planned in 2018, the Joint ExomarsSteering Board concluded at a meeting of the team that alaunch in 2020 would be best.

On March 14, the Roscosmos State Corporation andthe European Space Agency had launched the Exomars2016 mission which is due to reach Mars in October thisyear.

The successful implementation of both missions willallow Europe and Russia to jointly explore and validatecutting-edge technology for Mars entry, descent and

landing, control of surface assets and to develop moresystems that can be used in other missions to explore thesolar system.

Second Exomars

mission in 2020

Exomars 2016 was launched using the Proton-Mrocket, at the Baikonur cosmodrome. PHOTO: REUTERS

SHUBASHREE DESIKAN

tionarily conserved, namely,that they would be replicatedin the case of humans. But thisbelief has been shattered as thenew observations show thatboth with respect to the timeof onset of differentiation andthe pathways taken, humansdiffer from mice! Thus, the ma-jor discovery is in figuring outthat cell lineage specificationis species specific.

Janet Rossand, writing inNature, comments that thereare limitations to this study asthe cultured embryos arelargely two-dimensional andare imperfect models of nor-mal ones.

The methods, therefore,need to be refined to yield use-ful results.

In a major breakthrough inhuman embryology, re-searchers have breachedthe 7-day limit to studyinghuman embryos outside

the maternal womb. The im-proved techniques employedby them in nurturing the “blas-tocyte,” a small hollow ball of cells formed after fertilizationof the egg by the sperm in thelab, allowed them to study themolecular and cellular devel-opment that occurs during thefirst 14 days after fertilization.Being able to clinically ob-serve the blastocyte beyond

seven days is important be-cause this is the time when theblastocyte normally attachesitself to the mother’s womb ina process termed implanta-tion. Over the next few days,the blastocyte undergoes a dif-ferentiation process into threebasic cell layers (called gastru-lation) from which the bodilystructures of the embryo, and,eventually, the individual, arederived. Studying the blasto-cyte beyond seven days hasbeen extremely challenginguntil these new techniqueswere developed by the Rock-feller University, researchers,who published their results inNature recently.

“This portion of human de-velopment was a completeblack box,” says Ali Brivanlouan author of the paper.

The development of mouseblastocyte “lineage specifica-tion” as this process is called,was studied previously by co-author Magdalena Zernicka-Goetz and colleagues fromUniversity of Cambridge. Theprocess is now well under-stood. It was earlier believedthat these pathways are evolu-

The 14-day rule

There are also external lim-its to how researchers in thisfield may proceed. For in-stance, there is the 14-day ruledisallowing research on hu-man embryos beyond fourteendays after fertilization. This isa law in some countries includ-ing Canada, the U.K. and Spainand falls under the list of rec-ommended scientific regula-tions in countries such as In-dia, the U.S., Japan and China.

Though it sounds arbitrary,the fourteenth day is an impor-tant day in the development of the embryo because it is whenthe “primitive streak,” a faintband of cells marking thehead-to-tail axis, is formed.The primitive streak is the first

indication that the embryo hasdeveloped a biological identi-ty, because, before this stage,the embryos can divide in two.

This has therefore been cho-sen as the point to draw theline for human embryoresearch.

In a comment piece in Na- ture, Insoo Hyun and co-au-thors argue for a relaxation of this rule, as such researchcould be crucial not only in theprevention of early pregnancyloss, but also in understandingearly development. In revisit-ing the 14-day rule, the authorsdissuade people from viewingit as an ethical tenet en-trenched in biological fact;rather, they urge them to viewit as a “public-policy tool de-signed to carve out a space forscientific research and simul-taneously show respect for thediverse views on human em-bryo research.” They furtheradvocate having discussions atthe international and nationallevels, with researchers takingan active part.

In the context of India, thesubject offers a good scope forsetting up lines of discussionand informed debate, with re-searchers taking the initiativeto educate and inform the pub-lic as well as the policymakers.

Studying the blastocyte beyond seven days is an extremely challenging task.

SHUBASHREE DESIKAN

LIFE BEGINS | A human embryo 12 days after fertilization in vitro.Different cell types marked different colours.Photo: AP/Rockfeller University

The majordiscovery isin figuringout that celllineagespecificationis speciesspecific.

A first look into early human

embryonic development

The year 2016 marks anend of the era of Mil-lennium Develop-ment Goals (MDGs),which drove the glob-

al development agenda sincethe new millennium. TheMDGs have paved the way forSustainable DevelopmentGoals (SDGs) that the worldwill strive to achieve over thenext fifteen years. It is an op-portune moment to reflect onthe successes and the lessonslearnt from the MDG era andthe possible way forward forachieving the ambitious and

inclusive agenda of SDGs inthe health sector.

Lessons learntFirst, high-level political

commitment globally and na-tionally drove much of theprogress towards MDGs. Weneed nothing less for theSDGs. Second, while MDGshelped improve the overallhealth of nations, the focuswas on the aggregate targetsignoring inequities withincountries. To understand thereal progress and challengesthere is a need to disaggre-gate data by gender, econom-ic status and geographical ar-ea. Thirdly, neither theeconomic benefits of goodhealth nor the direct financialconsequences of ill-healthwere sufficiently captured byMDGs. We know that nationsrequire a healthy population

to prosper. When people dofall sick, high out-of-pocketexpenditures on healthcare

lead to financial hardship anddiminish the ability of thepopulation to contribute tothe economy. In India, nearly60 million people fall intopoverty just paying forhealthcare, while many moreabstain or delay seekinghealthcare due to financialdifficulties.

Fourthly, MDGs did notcapture the importance of prevention, early detectionand response to diseasethreats. The growing non-communicable disease(NCD) epidemic and conse-

quent premature deathscould be prevented by reduc-ing lifestyle risk factors, spe-cifically tobacco use, food in-take, inactivity, and alcoholconsumption. In addition,diseases like SARS, Ebola,MERS and Zika pose threatsto global health security andhave the potential to cripplecountries. MDGs missed thisimportant issue.

Lastly, it is not only about‘more money for health, butalso more health for money’;the MDGs focused on ad-dressing specific disease andsymptoms, which led to frag-mentation, duplication andinefficiencies in the healthsystems. WHO estimates thatnearly 20-40 per cent of allhealth resources are wasted.

The way forwardUnlike MDGs, which had

three dedicated health goals,the SDG agenda has only onehealth goal (SDG-3) which

aims to ‘ensure healthy livesand promote well-being forall in all ages’. The 13 broadtargets under health goal arein-tune with current globalepidemiological reality. Be-sides the unfinished MDGagenda of reducing maternaland child mortality and tack-ling the communicable dis-ease, the SDG-3 also aims totackle the epidemic of NCDs,substance abuse and ill-ef-fects of environmental haz-ards. Health is also interlin-ked to several other SDGsrelated to poverty, genderequality, education, food se-curity, water sanitation etc.

The unprecedented scopeof SDGs provides immense

opportunity to bring health atthe centre of economicgrowth agenda, which is PM

Modi’s topmost priority. Uni-versal Health Coverage(UHC), which is an explicittarget under SDG-3, can act asthe anchor to guide and in-form SDG goals in health.

It is interesting that thesethoughts have their roots inwhat was envisioned by Ma-hatma Gandhi. He said, “Re-call the face of the poorestand weakest man you haveseen, and ask yourself if thisstep you contemplate is goingto be any use to him.” It is thisthinking, which was reflectedin the MDGs and is now evenmore central in the SDGs.

Towards sustainabledevelopment

India can progress towardssustainable development in

health if it follows the follow-ing five steps.

First, health must be highon the national and stateagenda, as it is the corner-stone for economic growth of the nation. This requires highpolitical commitment andcollective long-term effortsby ministries beyond theMinistry of Health to investin health. The proposal in In-dia’s draft National HealthPolicy 2015 to raise public tohealth expenditure to 2.5 percent of the GDP by 2020 iscommendable.

Second, India should in-vest in public health and fin-ish the MDG agenda throughfurther improvements in ma-ternal and child health, con-fronting neglected tropicaldiseases, eliminating malaria,and increasing the fightagainst tuberculosis. For allthese challenges, it is clearwhat needs to be done; pro-grammes and interventionsneed to be taken to scale, witha central emphasis on equityand quality of services.

Third, accelerate the im-plementation of universalhealth coverage. UHC is im-portant to prevent peopleslipping into poverty due toill health and to ensure every-one in need has access togood quality health services.To complement tax revenuebased health financing, incre-mental expansion of prepay-

ment and risk pooling mecha-nisms such as Social HealthInsurance are worth consid-

ering. UHC is at the core of SDGs and in the interest of people and governments.

Fourth, build robust healthsystem in all aspects andstrengthen both the rural andurban components, withcomprehensive primaryhealth care at its centre. Giv-en the magnitude of the pri-vate sector in India, more ef-fective engagement withprivate healthcare providersis vital. Appropriate contract-ing modality, which is an im-portant feature under the So-cial Health Insurance or

RSSY, can be worked out andprivate sector can be instru-mental in complementing thepublic sector as demonstrat-ed by different country expe-riences, including Thailandand Philippines.

Finally, develop a strongsystem for monitoring, eval-uation and accountability. Itis absolutely essential to reg-ularly review and analyse theprogress made for feeding in-to policy decisions and revis-ing strategies based on thechallenges.

In conclusion, the SDGshave the potential to create aworld where no one is left be-hind.

The SDGS also make it pos-sible to achieve what theWHO constitution mandates:attainment by all peoples of the highest possible level of health.

Henk Bekedam(The author is the WHO

Representative for India)

SDGs: big agenda, big opportunities for India

AWARENESS | Cardiovascular diseases, cancer, respiratorydiseases and diabetes are the big four NCDs. PHOTO: K GAJENDRAN

Studying a nearby starhas given scientists afascinating insight intohow the Sun may havebehaved billions of

years ago.A team of international as-

tronomers, including professorStefan Kraus of the Universityof Exeter in Britain, used cut-ting-edge techniques to createthe first direct image of surfacestructures on the star Zeta An-dromedae, found 181 light yearsfrom Earth.

In order to image the star’ssurface during one of its 18-dayrotations, the researchers useda method called interferometrywhere the light of physicallyseparate telescopes is com-bined in order to create the re-solving power of a 330 mtelescope.

Found in the northern con-stellation of Andromeda, thestar showed signs of “starspots”the equivalent of sunspotsfound within our own solar sys-tem. The pattern of these spots

differs significantly from thosefound on the Sun.

The researchers suggestthese results challenge currentunderstandings of how magnet-ic fields of stars influence theirevolution.

Furthermore, they believethat the findings offer a rareglimpse of how the Sun behavedin its infancy, while the solarsystem was first forming.

“Most stars behave like giantrotating magnets and ‘starspots’are the visible manifestation of

this magnetic activity. Imagingthese structures can help us todecipher the workings that takeplace deep below the stellar sur-face,” said Kraus.

“While imaging sunspots wasone of the first things that as-tronomer Galileo Galilei didwhen he started using the newlyinvented telescope, it has takenmore than 400 years for us tomake a powerful enough tele-scope that can image spots onstars beyond the Sun,” added

John Monnier, professor of as-

tronomy in University of Michi-gan. It’s important to under-stand the Sun’s history becausethat dictates the Earth’s history:its formation and the develop-ment of life.

“The better we can constrainthe conditions of the solar envi-ronment when life formed, thebetter we can understand therequirements necessary for theformation of life,” said RachaelRoettenbacher, who conductedthis research as part of her doc-toral thesis at University of Michigan.

The findings were publishedin the scientific journal Nature.

IANS

Starspots on nearby star give fresh insight into Sun's infancy

Some of the sun’s mysteriesunravelled. PHOTO: REUTERS


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EducationPlus02 THE HINDU | MONDAY |MAY 16,2016- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

NOIDA/DELHI

SNAPSHOTS

How flytraps work

» Though venus flytraps consumeinsects, their ancestors probably did not.A paper published in Genome Research suggests that flytraps may have rewiredthe traditional plant defence machineryto eat insects in nutrient-poor soils.

Chewbacca on earth

» A recently discovered black,flightless, hairy species of weevil, about4 mm long, living in the tropical forestsof New Britain, an island off the coast of Papua New Guinea, has been namedTrigonopterus chewbacca after thewookie Star Wars character.

Wind around blackholes

» Astronomers have detected a strongwind of fast-moving, neutral particlesflowing from the black hole, V404 Cygni.Published in Nature, this study helpsexplain how blackholes absorb materialfrom their accretion discs.

LHC restarts after delay

» On May 9, the Large Hadron Colliderre-started its experiments in collidingproton beams and looking for newphysics. The delay in starting was due toa weasel-like animal that caused a shortcircuit

SUNTAN

Why do we tan after being exposed to sunlight? - Janani Nilahari, Chennai.

It is a protective mechanism exhibited by the skin to protect thebody against sunburn, skin damage and, sometimes, skin cancer. Onabsorbing the UV-A and UV-B portions of the sunlight, DNA damagecan take place with the formation of pyrimidine dimers. In order toprevent this, melanocytes present in the skin produce melaninthrough a process called melanogenesis. Melanin (Pheomelanin isred and Eumelanin is brown in colour) is a dark pigment which, onreaching the site of exposure, prevents further damage due tosunlight by absorbing the sunlight. Concentration of melanin in theexposed areas leads to darkening of the skin. This is generally knownas tanning.

UV-A radiation (315 nm to 400 nm) oxidises existing melanin fromthe melanocytes and reorganises it, causing the actual tan in theskin. Tan due to UV-A is immediate and it cannot give long-termprotection unlike UV-B. UV-A is not blocked properly by sunscreensbut blocked to some degree by clothing. Excessive exposure to UV-Acan cause DNA damage and also cancer.

UV-B ranges from 280 nm to 315 nm. It can cause direct DNAdamage and actual melanogenesis which results in delayed tanning.UV-B gives much protection against sun burn on a long-term basis. Itis effectively controlled by sunscreens. But UV-B is associated withthe risks of ageing, skin cancer (due to DNA damage) and long-termtanning. UV-B is responsible for production of vitamin D in our body.

Hence, one can judiciously choose the time and extent of exposureto sunlight to enjoy the benefits of the sunlight and at the same timenot becoming vulnerable to its ill effects.

- Dr. T. Bhavani, Bengaluru

THIS WEEK’S QUESTION

Why is the wave height of tsunami not so big in open seas? - Dr. Sagar Chahar, Delhi

»QUESTIONCORNER

Readers may send their questions/answers [email protected]

Aquarter century of or-nithological observa-tions of wetland birdsof Kerala come with amixed bag of joy and

despair for birders.At a time when the wetlands

of the State are facing multi-pronged threats, the populationof a few bird species has beenfound soaring whereas someothers have nose-dived in thepopulation chart. Researchersfocused their attention on thedata generated from the fourRamsar sites of the State - Sas-thamkotta Lake, AshtamudiLake, Vembanad Lake and KoleWetlands - and also the otherimportant wetland habitats toget a bird’s eye view of the pop-ulation trends of wetland avian

fauna.The brightly coloured purple

swamphen is one species thathave thrived amidst widespreaddestruction of its habitats. Itspopulation trend analysis dem-onstrated that the species hasincreased in Kerala during thelast decade.

Ornithologists arrived at theconclusion after evaluating thebird data picked up from theAsian Water bird Census(AWC) held between 1987 and2014. The annual census, coordi-nated by Wetlands Internation-al, also happens to be the firstcountry-wide citizen science

activity on natural history in In-dia. An influx of Eurasian coot,which was an added to the list of Kerala birds during the late

1980s, has been reported in theState during winter season,noted P.O. Nameer of KeralaAgricultural University, the leadauthor of the population assess-ment paper.

The painted stork, earlierevaluated as a vagrant visitor towetlands of Malabar and southKerala has spread beyond the re-gion they are generally foundpredicted ornithologists, aftertaking into account the reportsof its sightings in other parts of the State.

The population of AsianOpenbill, extremely rare duringthe 1970s, has remarkably in-

creased since 2001, with at leastfour census reporting the pres-ence of more than 3,000 birds.So is the case of Eurasian spoon-bill as there have been severalreports of sighting of largeflocks from Kole Wetlands,Vembanad Lake and KuttanadWetlands. Same is the case withblackheaded Ibis.

Indian spotbilled duck, glossyibis, oriental darter, Asian wool-lyneck and spotbilled pelicanrecorded increased presencewhereas the population of theriver terns and cormorants re-mained stable.

But the bird group of terns un-derwent a steady decline overthe years. From the nearly

30,000-strong population in1993-94, it had plummeted tojust near 10,000 in the last dec-ade. The loss of estuarine hab-

itat like Purathur in Malappu-ram district and disturbances inother estuaries might have con-tributed to this decline. The de-cline was evident in the relative-ly stable sites such as KoleWetlands, rued theornithologists.

The population of whiskeredtern, which form the majorchunk of the population of theterns in the State, too has fallensignificantly. Gulls too painted agloomy picture as they weresighted in lesser number duringthe past few censuses. The Bird-Life International has recordedthat 11 water bird species of Ker-

ala come under the IUCN Redlist threatened categories withthe black bellied tern being oneof the ‘Endangered’ waterbirdspecies in Kerala.

The only report of black bel-lied tern during AWC was fromthe Kole Wetlands. great knot, a‘vulnerable,’ trans-continentalmigrant, has been reported fromfour sites whereas the Asianwoolly neck stork (another vul-nerable species), has been re-ported from 44 wetlands acrossthe State.

Threats identifiedDemographic pressure, in-

dustrial development, pollu-tion, urbanisation, agricultureand aquaculture and watertransport have been addingpressure on the wetlands of theState.

Reclamation of wetlands andthe aquatic ecosystems, whichare often considered as waste-lands, is spelling trouble to sev-eral taxa. The stake nets used forfishing removes a wide array of non-target organisms, which arefunctionally important to theaquatic environment. Destruc-tive fishing practise are also tak-ing a toll on the bird population,it was reported.

Unregulated fishing, reclama-tion of wetlands, dumping of solid waste and domestic sew-age too posed threats to the wet-lands of Kerala, according toornithologists.

Asian waterbird census data causes mixed feelings

Painted stork and purple swamphen (top right) which have increased in number; whiskered tern (below) whose count has reduced.PHOTO: SPECIAL ARRANGEMENT

K.S. SUDHI

This is the first country-wide citizen science activity on this scale on natural history in India.

The climate change that oc-curred about 34 millionyears ago may hold thereason as to why humansoriginated in Africa and

not in Asia. More specifically, thedeterioration of climate markingthe Eocene-Oligocene Transition(which occurred about 34 millionyears ago) could have acted as anevolutionary filter, allowing dif-ferent types of primates to evolvein Africa as compared to Asia.The ensuing dominance of thesubset of primates known as an-thropoids in African regionsmust have led to the evolution of humans there, according to a pa-per in Science. Therefore, eventhough the earliest primate fos-sils have been found in Asia, theactual evolution of humans tookplace in Africa.

Geological calendar

The geological calendar relat-ing to the evolution of primatesand humans encompasses the so-called periods of which two are of interest here — the Paleogeneand the Neogene. The Paleogene,which lasted over 43millionyears, beginning 66 million yearsago (mya) and ending about 23mya, was the time when mam-mals evolved from simpler forms.

This was followed by the Neo-gene period (starting from theend of Paleogene to about 2.5

mya) during which time early hu-mans evolved.The Paleogene itself is divided

into three epochs: the Paleocene,Eocene and Oligocene.

Nearly 55 mya, the earth suf-fered a global increase in temper-ature of about 5 degrees Celsius.This is known as the Paleocene-Eocene Thermal Maximum. Dur-ing this, the primates, from a sub-

set of which humans eventually

evolved, being highly sensitive totemperature changes, migratedfrom their place of origin in lowerlatitudes, to the northern land re-gions. Subsequently, temper-atures fell during the Eocene-Oli-gocene Transition. Marking thiswas a deterioration of climatewhich caused these primates toagain retreat to lower latitudes.

Asian anthropoidsIn a paper published in Science,

Xijun Ni and coworkers study arecently discovered set of fossilsof primates from the early Oligo-cene period found in the Yunnanprovince of southern China.These fossils point to an Africanorigin of humans in the Neogeneperiod, even though anthropoidsoriginated in Asia.

“The global climate deteriora-tion, which happened 34 millionyears ago, changed the fate of an-thropoids. We suggest that this

global climate deterioration is anevolutionary filter for primates,”says Xijun Ni in an email to thiscorrespondent.

The authors find that of the sixfossils studied, only one is an an-thropoid. Earlier known recordsof primate fossils from the LateEocene period from China,Myanmar and Thailand haveshown a domination of stem an-

thropoids. So the lack of anthro-

poids in the set of fossils discov-ered now, which date latergeologically, could be attributedto the filtering mechanismcaused by lowering of temper-ature and deterioration of climatethat marked the Eocene-Oligo-cene Transition, the authors infer.

Dr Ni clarifies, “In Asia, this[evolutionary] filter removedmost of the anthropoids but leftlemur-like primates. In Africa,the effect of this filter is on the op-posite side. It removed most of the lemur-like primates but gaveanthropoids more opportunities.After the filtering, the evolution-ary center of anthropoids movedfrom Asia to Africa.”

They also consider a fossil col-lection from Pakistan, dated at alate early-Oligocene and find evi-dence of a few primates. Howev-er, these were identified as be-longing to those species of small-bodied primates which did

not evolve into humans later.In a complementary manner,the late Eocene-early Oligoceneprimates from the Afro-Arabianregion had shown a very differentresponse to the Eocene-Oligo-cene Transition. There the an-thropoids diversified “taxonomi-cally and ecologically,” leading tothe eventual evolution of humansin the Neogene period.

Oligocene fossils explain anthropoid distribution

SHUBASHREE DESIKAN

The fossils found in Yunnanprovince, China. PHOTO: REUTERS

Syncytin is known to be more abun-dant in the first trimester embryo than

later stages, but Moore and Bikem Soy-gur from Akdeniz University, Turkey,wanted to narrow down further. “Wewere surprised it was present on em-bryos before implantation,” said Moore.This indicated that syncytin may beplaying a role in another hallmark of early embryonic development, implan-tation. They duo presented the results of their investigation in a paper publishedon April 12 in Human Reproduction journal.

Stickiness mattersImplantation is the stage at which the

5-7 day old embryo fixes itself on the wallof the uterus. To probe into syncytin’spossible role in implantation, the scien-tists looked at pre-implantation em-bryos donated for research to identifywhich cells of the embryo first producethe protein. They found that most of thesyncytin was on cells which stick theembryo to the womb at implantation,suggesting syncytin is important at thisstage.

The mechanism by which syncytin-1facilitates implantation is still not entire-ly clear, but Moore presented a likely ex-

planation: “Most probably (it does this)by helping the embryo to first stick toand then squeeze between the cells of the lining of the womb.”

Before this evolutionary event, and inother mammals, there have been genesidentified that function similar to syncy-

More than 25 million yearsago, a virus infected pri-mates and left some geneticmaterial behind. Many suchviral genes were passed on

to future generations and eventuallysome of them became a permanent fea-ture of the human genome. About 8 percent of human DNA is estimated to havecome from viruses; many segments ap-pear to be “junk,” but a number of themhave been found to have important func-tions. Syncytin-1 is one such gene.

In viruses, syncytin-1 produced a pro-tein that helped it stick to host cells andfuse with them so that they could repli-cate without getting noticed by thehost’s immune system, explained stemcell biologist Harry Moore from the Uni-versity of Sheffield in an email interview.Syncytin-1 has been a gene of interest ev-er since it was discovered in human pla-centa, the organ that appears duringpregnancy and mediates nutrient uptakeby the foetus from the mother. It ap-peared that this gene was crucial for the

formation of placenta and its altered ex-pression was linked with conditions of abnormal placentation.

tin to enable embryo implantation and aplacentation, explained Moore. “But

they evolved, new retroviral infectionsoccurred and if this was better for theembryo the genes were retained and theprevious genes then became dysfunc-tional,” he said, adding that if not for thisviral infection of our ancestors and sub-sequent incorporation of syncytin-1, hu-mans probably would not have evolved.

Possible applicationsUnderstanding early embryonic de-

velopment is required for refining cur-rent treatments of pregnancy-related is-sues. The scientists look forward tobeing able to develop blood tests basedon their results to identify pregnanciesthat might be at risk and also develop ap-propriate therapies. But before this,more functional studies are needed. “Itwill be necessary to see if embryos fromwomen who suffer with conditions suchas recurrent miscarriage have unusualsyncytin production,” said Moore, add-ing that efforts were also underway tofind better ways to mimic embryo im-plantation such as in 3D cell cultures in

order to study the process more closely.Nandita Jayaraj is a freelance writer

based in Bengaluru.

The gene syncytin's role was key, according to the researchers.

NANDITA JAYARAJ

Altered expression of syncytin-1 waslinked to abnormal placentation. Photoused for illustrative purpose FILE PHOTO

Early viral infection may have facilitated humanevolution

A

faint blue galaxy situatedabout 30 million light yearsfrom the Earth and locatedin the constellation “Leo Mi-nor” can shed new light on

birth of the universe.Astronomers from Indiana Univer-sity (IU) found that a galaxy nick-named Leoncino or “little lion” con-tains the lowest level of heavychemical elements or “metals” everobserved in a gravitationally boundsystem of stars.

“Finding the most metal-poor gal-axy ever is exciting since it can helpcontribute to a quantitative test of theBig Bang,” said professor John J. Sal-zer from Indiana University’s Bloo-mington College of Arts andSciences.

There are relatively few ways to ex-plore conditions at the birth of theuniverse. Studying low-metal galax-ies is among the most promisingmethods that scientists pursue.

This is because the current accept-ed model of the start of the universemakes clear predictions about theamount of helium and hydrogen pre-sent during the Big Bang.

The ratio of these atoms in metal-poor galaxies provides a direct test of the model.

To find these low-metal galaxies,

however, astronomers must look farfrom home.

Our own Milky Way galaxy is apoor source of data due to the highlevel of heavier elements created

over time by “stellar processing,” inwhich stars churn out heavierelements.

“Low metal abundance is essential-ly a sign that very little stellar activityhas taken place compared to mostgalaxies,” added Alec S Hirschauer,graduate student.

The results were presented in a pa-per that appeared the Astrophysical Journal.

Leoncino is considered a memberof the “local universe,” a region of space within about one billion lightyears from Earth and estimated tocontain several million galaxies.

Aside from low levels of heavierelements, Leoncino is unique in sev-eral other ways.

A so-called “dwarf galaxy,” it is on-ly about 1,000 light years in diameterand composed of several millionstars.

The Milky Way, by comparison,contains an estimated 200 billion to400 billion stars.

“We’re eager to continue to explorethis mysterious galaxy,” Salzer noted.

IANS

Rare blue galaxy can shed

light on birth of the universe


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SNAPSHOTS

Most efficient solar cell

» University of New South Walesresearchers have developed a new solarcell configuration which has unfocusedsunlight-energy conversion efficiency of 34.5 per cent, according to a reportposted on the university website. This isa world record and is close to thetheoretical limits for such a device.

GM mosquitoes set to takewing

» Science journal reports that millionsof genetically modified mosquitoes areabout to be released in the GrandCayman island. It s hoped that these willmate with other mosquitoes, whichhelps spread Zika virus, and produceunviable offspring. This is expected toprevent spread of Zika virus.

How hornbills keep cool

» Thermal imaging on a species of hornbill has shown that they vent heatfrom their beaks. They manage to cooldown by dilating their blood vessels toincrease the blood flow in theiruninsulated beaks, a study published inPLOS ONE revealed.

Early eukaryote fossil

» A 1.56 billion year old fossil of anorganism may well be the earliestmulticellular life form, says a studypublished in Nature Communications.This pushes back evidence formulticellular life forms to a time whenthe Earth was very hot and oxygen wasscarce. This pushes the timeline back bynearly a billion years.

TSUNAMI HEIGHT

Why is the wave height of tsunami not so big inopen seas? - Dr. Sagar Chahar, Delhi

Tsunami is a Japanese word meaning harbour wave. Tsunamiwaves are somewhat similar to the wind generated waves wesee at a beach. Wind generated waves are restricted to a thinlayer below the water surface and the up-down oscillations of the water particles (typically 0.1 – 3 m at the surface) quicklydecrease as one moves down from the water surface. We cancreate such waves by a paddle.Tsunami waves, on the other hand, are created by a large motionof the earth’s crust, for example in an earthquake. A large plate(hence large wavelength) of the earth’s crust creates thesewaves by displacing water and the energy liberated is huge.Wave amplitudes are small (0.1 – 1 m) but the wavelength islarge, typically 100 to 1,000 km. Oscillations of water particlesare not just restricted to the water surface but are distributed inthe entire depth. We cannot create such waves by a paddle.Because of the large volume of water involved, energy of tsunami

waves is large even though the amplitudes are small. This is whyit is difficult to observe the height of tsunami waves in the opensea.But the destructive power of the tsunami waves is felt when theyreach the seashore. Here the same energy gets concentratedinto a smaller depth and hence amplitude becomes very largeand gets noticed.Thus, the tsunami waves correspond to large amount of energyliberated in a large volume with relatively small amplitudebecoming noticeable only when the waves reach shallow waters.- Prof. Mohan D. DeshpandeM.S. Ramaiah University of Applied Sciences, Bengaluru

THIS WEEK’S QUESTION

How does an ATM work on touching t he glass onthe machine? - K Ananthanarayanan, Kanyakumari, Tamil Nadu

» QUESTIONCORNER


The Earth could contain near-

ly one trillion species, of which 99.999 percent are yet tobe discovered, says a studybased on the largest analysis of microbial data. The findings,published in the journal Pro- ceedings of the National Acad- emy of Sciences, suggest thatonly one-thousandth of onepercent of all the species havebeen identified till now.

“Estimating the number of species on Earth is among thegreat challenges in biology,”said one of the study authors Jay Lennon from Indiana Uni-versity in Bloomington, Indi-ana. The scientists combinedmicrobial, plant and animal da-tasets from government, aca-demic and citizen sciencesources, resulting in the largestcompilation of its kind.

Altogether, these data repre-sent more than 5.6 million mi-croscopic and non-microscop-

ic species from 35,000 locationsacross all the world’s oceansand continents, except Antarc-tica. “Our study combines thelargest available datasets withecological models and new ec-ological rules for how biodiver-sity relates to abundance. Thisgave us a new and rigorous esti-mate for the number of micro-bial species on Earth,” Lennonexplained. The estimate isbased on universal scaling lawsapplied to large datasets.

The authors are Jay Lennonand Kenneth Locey of IndianaUniversity. “Until recently,we’ve lacked the tools to trulyestimate the number of micro-bial species in the natural envi-ronment. The advent of new ge-netic sequencing technologyprovides a large pool of new in-formation,” Lennon added.

IANS

Earth home to atrillion species

The Vedic People,since 1600 BCE, havebred and used thecow in their homes,community and so-

ciety. While these ancient In-dians were familiar with alarge number of animals(horses, cats and tigers, dogs,deer, elephants and even therhinoceros) the cow has al-ways been held and wor-shipped in maternal terms(go-matha ). This sanctity of the cow is respected to thisday. She is tame, gentle, givesus our daily milk, and we useeven her droppings for a va-riety of purposes.

These are already enoughreasons to admire and adoreher; yet some people have

tried to thrust several‘unique’ but, alas, scientifi-cally untenable properties on

the cow. My cousin Sunda-ram had sent me one such setof claims, which are found inthe site https://www.iskcon-bangalore.org/blog/why-should-i-not-kill-cow/.There are a few other siteswith similar ‘scientific’claims. In this column, I wishto point out whey theseclaims are scientificallyuntenable.

Here is one such claim.“One cow was regularly fed aparticular quantity of a poi-son every day. After 24 hours,its blood, urine, dung andmilk were tested in a lab tocheck where the poisoncould be found. In this way,the tests were done not for 1or 2 days, but continuouslyfor 90 days in All India Insti-tute of Medical Sciences (AI-IMS) New Delhi. The re-searcher did not find any

trace of poison in milk, blood,urine or dung of that cow.Then where did this poison

fed for 90 days go? The go- matha hid the entire poisonin her throat. This is a specialquality that no other animalhas”.

Comment: Well, my en-quiries with some facultymembers at the AIIMS sug-

gest that no such experimentwas done there at all. The In-stitute’s Animal Ethics Com-mittee would not have al-lowed feeding any poison to

animals in the first place —and for 90 continuous days!!

Claim 2: “The cow is the

only creature that inhales ox-ygen and also exhalesoxygen.”

Comment: Other thanplants and mosses that pho-tosynthesise, there is no liv-ing being that exhales ox-ygen. The oxygen that isnoted upon exhalation is partof the (unused) oxygen in-haled. The lungs of any ani-mal are not efficient in deliv-ering all oxygen from theinhaled air. Some of this ox-ygen that was not absorbed isexhaled. As https://www.qu-ora.com/Do-cows-really-ex-hale-oxygen. points out, thisis the reason why mouth-to-mouth resuscitation works.

Claim 3: “Cow milk hasthe quality of counteringpoison.”

Comment: Poison is awide word. What poison?Cyanide? DDT? And what

proof do we have? Sciencewill not accept (neither willlaw) unless proof is given.

How do we prove (or dis-prove) the unprovable?

Claim 4: “Cow urine is thebest killer of microbes.”

Comment: That urine(human, cow’s…) can kill bac-teria is known. The mecha-nism is also known; it is theacidity of any animal urea(low pH value around 5), thepresence of urea, and ammo-nium compounds (vide D.Caye, 1968, Journal of Clinical Investigations, pp. 2374-90)The cow’s urine is no differ-ent (paper by A. Ahuja et al.,International Journal of Re- cent Advances in Pharma- ceutical Research,April 2012;2(2): 84-87).

Claim 5: “We can savefrom radio-waves by plaster-ing the home floors and areaoutside the home withcow-dung.”

Comment: “Radio-

waves” is a broad term, withno specification of the fre-quency/wavelength or

strength/intensity. Ordinaryradio and TV operate verywell indeed, whether thehouse is plastered with cowdung or not, and so do cellphones and wi-fi. Indeed, thetrouble with such statementsis their very generality.

Claim 6: “If 10 grams of cow-ghee is put in fire (yag-nya), 1 ton of oxygen isgenerated.”

Comment: This claim istotally against the laws of physics. 10 grams simply can-not generate 1,000 kilogramsin any manner.

None of the claims made inthe above article can be sup-ported by science, bar per-haps one, namely, that cowurine has the ability to killsome microbes, and that too,with some reservation aboutthe uniqueness of the cow inthis context. And there is no

point or logic in dismissingscience, saying “they willprove it some day,” or “they

are just against Hindubeliefs.”

Many of us Hindus reverethe cow. This sense of rever-ence is touching, and uniqueindeed. We are moved in ad-miration and gratitude to thegreat help she has offered tomankind through her milkand her ability to producehealthy babies (cows andbulls). The cow has been dei-fied not only as Kamadhenu,but even as the ordinaryhousehold variety.

But with claims such as theabove, the holy cow losessome of her nobility, and westart thinking of her more inutilitarian terms, which issomewhat demeaning to her.Plus such tall claims, so easilydismissed by science, make itworse. As the French philos-opher Blaise Pascal so aptlysaid: the heart has its reasons,

which reason does not know. D. BALASUBRAMANIAN

[email protected]

On the sanctity of the cow: the heart has its reasons

Many scientifically untenable properties are bestowed bypeople on the cow, which science can only refute.PHOTO: CH VIJAYA BHASKAR

» SPEAKINGOF SCIENCE

In the current global warm-ing scenario, extreme rain-fall events can be expectedto increase in both dry andwet land regions of the

world, according to a recentstudy published in the journalNature Climate Change.

The water vapour concentra-tion increase in the atmosphereper degree Celsius rise in tem-perature is 7 per cent accordingto the Clausius-Clapeyron theo-ry. Over the ocean, where evapo-ration is greater than precipita-tion (rainfall), such as in dryareas, the atmosphere will get

drier with increased globalwarming as the evaporated wa-ter, in the form of vapour, is car-ried away by winds, leaving be-hind a dry atmosphere. Andwhere the precipitation is grea-ter than evaporation such as inwet areas the areas will getwetter.

But over the land masses it hasbeen less clear as to how therainfall patterns change withglobal warming. Based on mod-els and observations it has beenfound that global average pre-cipitation increases only about 2per cent. In some way the atmo-sphere produces less rain.

One way that this could hap-pen is if rain increases at theClausius–Clapeyron rate whenit does fall, but falls less often,making precipitation eventsmore extreme. This is what isseen typically in general circula-tion models (GCM), the mostdetailed models of the climatesystem.

Another point is that the heatreleased by the condensation of water itself tends to pull moremoisture into a precipitatingsystem. This suggests that in-tense rain might instead in-

crease with warming at evenhigher rates than the Clausius-–Clapeyron rate— perhapstwice as fast, as some observa-tions for short timescales (min-utes to hours) seem to show. Onthe other hand, as the atmo-sphere’s capacity to evaporatemoisture from arid regions andto transport it away will increaseat the Clausius–Clapeyron rate,arid regions are expected to be-come drier still, and it seemsplausible that this would reduceall precipitation (from light toheavy) in these regions.

In the study, Dr Markus Donatof the Climate Change ResearchCentre, University of New SouthWales, Australia and colleaguesanalyse the changes in observa-tions of annual total and extreme(the most to fall on any singleday in the year) precipitationover land for 1951–2010. Theyfind that the fraction of theyear’s rain that falls on the wet-test day increases consistentlywith the Clausius–Clapeyronrate across both these regions.

GCM simulations of the sameperiod are consistent with theseobservations, and those of thelate 21st Century show that thetrend continues. Therefore, we

can have some confidence thatextreme precipitation risk willincrease not only in wet regionsbut also in dry ones.

The study, though significantfor its findings has the drawbackthat the tropics were poorly cov-ered. The global warming effectsare most severely felt in the trop-ics where complex physical in-teractions make prediction har-dest. Also, extreme rainfall datais widely available only on thedaily timescale. It cannot beknown how it will change onshorter and longer timescales,which will indicate the flood riskin different places.

More extreme rainfall on land masses predictedK.S. RAJGOPAL

Though significant, the study does not cover tropical land massesadequately. Photo: M. Vedhan

below is warmer, it is heavierthan the cooler, less saline layeron top..

“Warm, but salty water — ul-timately originating from theAtlantic Ocean resides near thebottom of the Arctic Ocean. If turbulence could somehowmix this water with that above,then, eventually, the surfacecould warm more rapidly, andthis would increase the rate of sea-ice melt. One mechanismfor mixing is the result of break-ing internal waves,” says BruceSutherland, University of Al-berta, Canada, the author of thepaper, in an email interview.

The internal movement of water within seas from cold,dense regions to warmer, light-er ones constitutes the largestobservable waves. These canstretch to wavelengths of over a

Internal waves, which movevertically through theocean, can sometimes passthrough “water staircases,”which are steplike varia-

tions of density of water, insuch as manner as to churn upthe underlying warm, salty wa-ter, thereby increasing the tem-perature of the top, cooler lay-ers, according to a paperpublished in Physical Review Fluids. This suggests a possiblemechanism by which the upperlayers of the Arctic Oceanwarm up, causing the ice tomelt.

Water staircases are steplikevariations of density of waterdue to steplike changes in tem-perature and salinity. Thoughinternal waves exist where the

density gradually increaseswith depth, they cannot propa-gate where the density is uni-form, for instance, within thesteps of the staircase. While thepassage of waves through a sin-gle step was studied earlier, theinteraction between waves andmultiple steps was not reallyunderstood well and is consid-ered for the first time in thispaper.

Ocean warmingThe Arctic Ocean has in-

flows coming from the PacificOcean and Atlantic Ocean. Inthis, the top layers consist of cooler and less saline water andbelow that is a layer of watercoming from the AtlanticOcean which is more saline andwarmer, too. The effect of salin-ity wins over that of temper-ature and so, though the water

hundred metres and travelfrom top to bottom. Like nor-mal water waves, these propa-gate due to a variation of densi-ty of the water and not whenthere is constant density. In astaircase-like formation,though the density is constantwithin the step, there is a jumpin density from one step to an-other. Hence, the wave’s energycan be transmitted from one in-terface to another.

Though not predominant,thermohaline staircases do oc-cur in many places. “As well asthe Arctic, they are persistentin the Caribbean Sea. This isdue to surface heating andevaporation resulting in warmsalty water overlying colderfresher water. They do not existwhere there are strong cur-rents, as in the Antarctic, which

have enough energy to stir upany staircases that might form,”says Dr Sutherland.

Selective filteringSo the scenario is that when

an internal wave strikes a den-sity staircase, a part of its ener-gy may be transmitted throughthe staircase. In other words,density staircases in the oceancan act to reflect short wave-length internal waves andtransmit longer wavelengthwaves. This is analogous to theselective transparency of glasswindows on modern buildingsthat have multilayered coatingsdesigned to reflect red light(long wavelength light) and al-low green-blue (shorter wave-length) light through

On reaching the ocean floor,the long-wavelength waves

which have been transmittedcause turbulence and mix upthe water. The warm watersthen rise to the top and warmthe top layers.

“Strong storms passing over

the Arctic typically generatewaves on the order of 10-100 kmhorizontal scale. As sea-ice re-treats and storms passing overthe increasingly non-ice-cov-ered ocean generate more andmore waves, it seems that still asubstantial fraction of this en-ergy can transmit to depth, andthis may consequently causemixing at depth that couldbring those deep warm (butsalty) waters closer to the sur-face. The filtering that my theo-ry predicts suggests that the en-ergy transmitted to depthmight be moderately smallerthan one would expect in theabsence of density staircases.But, for the most energeticwaves — those transmitted bystorms — the decrease is notsubstantial,” says DrSutherland.

When a vertical internal wave strikes this formation, a part of its energy may be transmitted through it.

SHUBASHREE DESIKAN

Unlike the surface waves we usually observe, internal waves in the ocean can stretch over scalesof 10-100 kilometres. This photo is used for illustrative purposes only. Photo: C. Ratheesh Kumar.

Waterstaircases aresteplikevariations ofdensity ofwater due tosteplikechanges intemperatureand salinity.

Water staircases in seas


5/5


NOIDA/DELHI

SNAPSHOTS

Interstellar driveover

» NASA has been called upon to launchan interstellar mission to Alpha Centauri,our nearest star system which is about4.35 light years from the sun, in 2069,the centenary of the Apollo 11 moonlanding.

Surviver squids

» A new study, published in Current Biology, says that the population of cephalopods – animals that includeoctopuses, squids and so on — is onthe rise. Their short life spans and rapidbreeding could have made themadaptable to environmental changes.

Citizen science triumphs

» A study published in Icarus, ofMoon Zoo, a website that asks citizenscientists to identify and classify craterson the moon, found that the citizenscientists' crater count was comparableto that done by experts, showing theway for citizen science projects.

Super-sized sperm

» In certain species of fruit fly, such asDrosophila bifurca, males, just a fewmillimetres in size, produce sperm withtail nearly 5.8 centimetres long. ANature report says, this could be arunaway-train effect resulting fromcomplex interplay of male and femalebenefits.

TOUCH SCREEN TECHNOLOGY

How does an ATM work on touching t he glass on the mac hine? - K. Ananthanarayanan, Kanyakumari, Tamil Nadu

There are many types of technology available but of them two are most common. The first is the‘Resistive’ touch screen. There is a flexible upper layerof conducting polyester plastic bonded to a rigidlower layer of conducting sheet, separated by aninsulating membrane.When the screen is pressed at a specific spot, itforces the polyester to touch the glass and completea circuit—ju st like pressing the key on a keyboard. Achip inside the screen figures out the coordinates of the place which is touched.The other one is ‘capacitive’ type screen. Thesescreens behave like two electrical conductorsseparated by an insulator—in other words, acapacitor. When the user brings his finger up to the

screen, it alters the electrical field by a certainamount that varies according to where the finger is.Capacitive screens can be touched in more than oneplace at once.Other technologies use are infrared, surface acousticwave, and near field imaging ones.The great thing about touch-screen technology isthat it's incredibly easy for people to use.- S. P. S. Jain, Greater Noida.

THIS WEEK’S QUESTIONS

According to Eins tein, a partic le moving at the speed of light reaches infinite mass.Then why is a photon massless? - Sivaranjani Senthilvel

Why do we feel urinating sensation beforeor during bathing? - Sanathan Das, Cuttack

»QUESTIONCORNER


In a study published in Cell Reports, Scien-

tists have discovered how a gene muta-tion found in several human cancers, in-cluding leukaemia, gliomas and melanoma,promotes the growth of aggressive tu-mours, a finding that may help develop newtreatment for the deadly diseases.

“We’ve found the mechanism throughwhich this mutation leads to a scramblingof the genome. That’s when you get reallymassive tumours,” said Eros Lazzerini Den-chi, associate professor at The Scripps Re-search Institute (TSRI) in the U.S. The re-search also suggests a possible way to killthese kinds of tumours by targeting an im-portant enzyme.

The researchers studied mutations in agene that codes for the protein POT1. Thisprotein normally forms a protective caparound the ends of chromosomes (calledtelomeres), stopping cell machinery frommistakenly damaging the DNA there andcausing harmful mutations.

POT1 is so critical that cells withoutfunctional POT1 would rather die than passon POT1 mutations. Stress in these cellsleads to the activation of an enzyme, called

ATR, that triggers programmed cell death.Knowing this, scientists in recent yearswere surprised to find recurrent mutationsaffecting POT1 in several human cancers,including leukaemia and melanoma.

“Somehow those cells found a way tosurvive and thrive. We thought that if wecould understand how that happens, may-be we could find a way to kill those cells,”said Lazzerini Denchi, who led the studyalong with Agnel Sfe ir of New York Univer-sity , School of Medicine.

Using a mouse model, the researchersfound that mutations in POT1 lead to can-cer when combined with a mutation in agene called p53.

When mutated, P53 overrides the protec-tive cell death response initiated by ATR.

Then, without POT1 creating a protec-tive cap, the chromosomes are fused to-gether and the DNA is rearranged, drivingthe accumulation of even more mutations.These mutant cells go on to proliferate andbecome aggressive tumours.

The findings led the team to consider anew strategy for killing these tumours.

PTI

Insight into tumour-causing mutations

Some pregnant womenwho are infected with Zi-ka virus transmit the in-fection to the foetus(vertical transmission).

Researchers now know how thevirus is able to cross the placen-tal barrier and infect the foetus.

The Zika virus infects and rep-licates in immune cells of the pla-centa (Hofbauer cells). The in-fected cells, which are not killed,allow the virus to pass throughthe placenta of pregnant womenand infect the brain cells of thefoetus. The results are publishedon May 27 in the journal Cell Host & Microbe .

That Zika virus infects theHofbauer cells became clearwhen an earlier study found Zikaviral antigen in these cells that

were collected from the placen-tal tissue of a foetus that unfortu-nately died as a result of Zika vi-

rus infection.Since Hofbauer cells have di-

rect access to foetal blood ves-sels, transmission of the virus tothe foetus becomes easy whenthese cells are infected with Zikavirus.

Mehul S. Suthar, the Corre-sponding author from the EmoryUniversity School of medicine,Atlanta, U.S., and his team foundthat the virus can also infect an-other type of placental cell calledthe cytotrophoblasts, but only af-ter a couple of days unlike in thecase of Hofbauer cells. Cytotro-phoblasts cells are found in themiddle layer of the placentalbarrier.

The team undertook lab stud-ies using Hofbauer cells and cy-totrophoblasts derived from full-term placentae of five womenwho delivered by Caesarean sec-

tion. They found that both cellstypes were permissive to Zika vi-rus infection. The Zika virus

used for the study was a straincurrently circulating in PuertoRico.

“Our study indicates that Hof-bauer cell type may be a targetfor Zika virus in the placenta andreplication in these cells may al-low the virus to cross the placen-

tal barrier and enter the foetalcirculation,” Rana Chakraborty, aco-author of the paper from

Emory said in a release.The placental cells from the

five donors showed different lev-els of viral replication, inflamma-tion and antiviral gene expres-sion, likely reflecting differencesin genetics in these individuals.

Hence, some women may have

the capacity to restrict Zika virusat different stages of the viral rep-lication cycle. Such differences

in pregnant women may be thereason why some women end uptransmitting the virus to the foe-tus while some others don’t.“Women with more susceptibleHofbauer cells may supporthigher levels of the virus replica-tion and subsequent spread tothe developing foetal nervoussystem,” they write.

Since infection during the firsttrimester or early second trimes-ter has been associated with theobserved increase in infantsborn with microcephaly, futurestudies should be directed atfinding out when the Hofbauerand Cytotrophoblasts cells aremost susceptible to Zika virus in-fection (first, second or third tri-mester).

As Hofbauer cells have beenfound to be the target cell withinthe placenta, antiviral therapies

should be developed to preventvirus replication within thesecells.

More light on how Zika virus infects the placenta

Infection during the first and early second trimesters has beenassociated with increase in cases of microcephaly. PHOTO: AP

R. PRASAD

Scientists report in Science Ad- vances of directly detected keyorganic compounds in comet 67P/Churyumov-Gerasimenko.

This bolsters the notion thatthese celestial objects deliveredsuch chemical building blocks forlife long ago to Earth and through-out the solar system.

The European Space Agency'sRosetta spacecraft made severaldetections of the amino acid gly-cine, used by living organisms tomake proteins, in the cloud of gasand dust surrounding the comet.

Glycine previously was indi-rectly detected in samples return-ed to Earth in 2006 from anothercomet, Wild 2. But there were con-tamination issues with the sam-ples, which landed in the Utah

desert, that complicated the scien-tific analysis.

“Having found glycine in more

than one comet shows that neitherWild 2 nor 67P are exceptions,”said Rosetta scientist Kathrin Alt-wegg of the University of Bern inSwitzerland, who led the research.

“Amino acids are everywhere,and life could possibly also start inmany places in the universe,” Alt-wegg added.

Altwegg and colleagues alsofound phosphorus, a key elementin all living organisms, and otherorganic molecules in dust sur-rounding comet 67P. It was thefirst time phosphorus was foundaround a comet.

Scientists have long debated thecircumstances around the originof life on Earth billions of yearsago, including the hypothesis thatcomets and asteroids carrying or-

ganic molecules crashed into theoceans on the Earth in early times.

Reuters

Rosetta finds building blocksfor life in comet 67P

Coral ecosystem thriving inthe Indian waters hascome under severe stresswith instances of coralbleaching being reported

from islands of Lakshadweep andsome parts of Andaman.

It is the thermal stress in theform of increase in Sea SurfaceTemperature (SST) during Aprilthat has proved disastrous for thecorals.

While bleaching has been wide-ly reported in the coral islands of Lakshadweep, some isolated inci-dents were reported from Anda-

man. Joint observations carriedout by the National Institute of Ocean Technology, Chennai, andthe Indian National Centre forOcean Information Services (IN-COIS), Hyderabad, confirmed thedevelopments, said Satheesh She-noi, director of the INCOIS.

Sea surface temperatureDuring the last couple of

months, an increase in the Sea Sur-face Temperature was observed inthe waters around the AndamanIslands, the Gulf of Mannar, andthe Lakshadweep Islands. Follow-ing the observations, warning wassounded in these areas for coralbleaching. The in-situ observa-tions carried out at North Bay,

South Andaman revealed the pri-mary signs of bleaching, accordingto a communication from theINCOIS.

“Coral bleaching takes placewhen the symbiotic relationshipbetween algae (zooxanthellae) andtheir host corals breaks down un-der certain environmental stress-es. This results in the host expell-ing their zooxanthellae. In theabsence of symbiotic algae, thecorals expose their white underly-ing calcium carbonate coral skele-ton and the affected coral colonybecomes pale in colour. Coral

bleaching can be activated andpersist during varied environmen-tal stresses,” explains a scientificdocument released by the Centre.

The SST was in the range of 32degree Celsius when in situ tem-perature observations were madeduring the last week of April in An-daman coast. However, the rainfollowing the development of a de-pression in the Bay of Bengal hasbrought down the SST therebyaverting the massive incidents of bleaching, Dr. Shenoi explained.

There existed a strong trend forbleaching but not to an alarming

level and only a few species werefound to be vulnerable to the trend,he explained.

In Lakshadweep, bleaching wasreported in the water around theislands of Kavarathy, Agathy andBangaram. The damage to the cor-al ecosystem was reported as deepas 30 metres, according to IdreesBabu, a scientist of the Departmentof Science and Technology,Lakshadweep.

The SST in the Lakshadweepwaters rose to 32 degree Celsiusagainst the normal temperature of 25 degree Celsius. There has notbeen much rain in region exceptthe scattered showers, said Mr.

Babu.The Lakshadweep region wit-

nessed a massive destruction of corals in 1997 when around 85 percent of the coral reef wasdestructed.

Coral regenerationAmidst growing concern about

the impact of coral bleaching, sci-entists have also brought out somegood news from the ocean depthsof Andaman. The branching coralsthat were destructed during the2004 South Asian tsunami havestarted regenerating in the region.The impact of bleaching would bedifferent in different species andsome may take 10 years or longer toregenerate, Dr. Shenoi pointed out.

Thermal stress impacts corals in Indian watersK.S. SUDHI

During the last couple of months an increase in sea surfacetemperatures was observed in these waters. PHOT

hindu sci tech may 2016 xaam.in

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