Postgenomic, precursor, expressed sequence tag, and massspectrometric peptidomic analyses allowed us to identify a singlegene leading to a novel 18mer-isoform of a bety-type pigment-dispersing hormone (PDH) that is identical in two waterflea species,Daphnia magna and Daphnia pulex. PDH is restricted to interneurons,ten types in the brain and two types in the visual ganglia, and doesnot occur in neurosecretory cells connected to neurohaemal areas.The neurons individually identified by immunohistochemistry (IHC)were virtually identical in terms of their positions and projectionpatterns in both species. Whereas the brain neurons are foundassociated with almost all major neuropils incl. the central body, thevisual ganglia neurons adjacent to and innervating the medullaclosely resemble the insect so-called pigment-dispersing factormedulla lateral neurons based upon positional and projection criteria.Since the latter neurons are established members of insect circadianclock systems, we analysed these neurons for IHC-detectablecircadian changes. Preliminary results under 12:12 h light dark cyclesshowed significant circadian changes in numbers and stainingintensities of the Daphnia medulla PDH neurons. These PDH neuronscomprise a simple system currently studied in more depth inbehavioural contexts. The discovered homologies to PDH-systems indecapod crustaceans and the well known clock system in severalinsects suggest evolutionary conservation of an ancient peptidergicinterneuronal system in arthropods.

Email Address for correspondence: johannes.strauss@zoologi.su.se

doi:10.1016/j.cbpa.2009.04.311

A10.21Poster Session – Tuesday 30th June 2009Dissecting the resolution of a fruit fly retina

Paloma T. Gonzalez-Bellido (University of Sheffield), Mikko Juusola(University of Sheffield), Rita Kostyleva (Dalhousie University), Ian A.Meinertzhagen (Dalhousie University), Trevor J. Wardill (Universityof Sheffield)

The Drosophila visual system copes with the strains imposed by asmall body size and successfully guides complex behaviors. Tounderstand a visual system, knowing its acuity is paramount. Theacceptance angle Δρ, is the parameter used to describe spatialperformance. Stavenga (2003) calculated Δρ=4.2°. However,through in-vivo recordings of intracellular photoreceptor responses,we have measured Δρ=8.6±3 (Mean±S.D.; n=13) in darkadapted flies. Such a disparity could be explained if the feedbacksynaptic connections in the fly eye (Meinertzhagen and Sorra, 2001)change the spatial properties of photoreceptor cells. To investigatethis possibility, we aimed to “disconnect” the visual system from theinput of photoreceptors R1–R6 exclusively at high temperatures andin a reversible manner by overexpressing shibirets1 (shits1) inphotoreceptors. shits1 causes synaptic vesicle depletion above 31 °C,but leaves neural communication intact at temperatures below 19 °C(Kitamoto, 2001).

Our results show that at the reported permissive temperature(19 °C), overexpressing shits1 causes decelerated phototransductionand neurotransmission. Additionally, the photoreceptor cells appearenlarged and contain multi-vesicular bodies. Furthermore, theterminals of photoreceptors overexpressing shits1 have a low vesiclecount, apoptotic mitochondria and coated microtubules. Goldimmuno-labeling confirmed that shibire protein coated the micro-tubules. Shpetner and Vallee (1989) reported the dynamin-micro-tubule interaction in-vitro, but to our knowledge this is the first studyreporting such interaction in-vivo.

Kitamoto (2001). J. Neurobiol. 47:81-92. Meinertzhagen and Sorra(2001). Prog. Brain Res. 131: 53-69. Shpetner and Vallee (1989). Cell59: 421-32. Stavenga (2003). J. Comp. Physiol. 189: 7245-7256.

Email Address for correspondence: p.gonzalez@shef.ac.uk

doi:10.1016/j.cbpa.2009.04.312

A10.22Poster Session – Tuesday 30th June 2009Function of the Shaw potassium channel within the Drosophilacircadian clock

James J. Hodge (Bristol University), Ralf Stanewsky (Queen MaryCollege University of London)

In addition to the molecular feedback loops, electrical activity isimportant for the function of networks of clock neurons in generatingrhythmic behavior. In order to determine the cellular mechanismsthat regulate resting membrane potential (RMP) in the native clock ofDrosophila we modulated the function of Shaw, a widely expressedneuronal potassium (K+) channel known to regulate RMP inDrosophila central neurons.

We show that Shaw is endogenously expressed in clock neurons.Differential use of clock gene promoters was employed to express arange of transgenes that either increase or decrease Shaw function indifferent clusters of clock neurons. Under LD conditions, increasingShaw levels in all clock neurons, or in subsets of clock neurons (LNdand DNs or DNs alone) increases locomotor activity at night. In free-running conditions these manipulations result in arrhythmic loco-motor activity without disruption of the molecular clock. ReducingShaw in the DN alone caused a dramatic lengthening of thebehavioral period. Changing Shaw levels in all clock neurons alsodisrupts the rhythmic accumulation and levels of Pigment DispersingFactor (PDF) in the dorsal projections of LNv neurons. However,changing Shaw levels solely in LNv neurons had little effect onlocomotor activity or rhythmic accumulation of PDF.

Based on our results it is likely that Shaw modulates pacemakerand output neuronal electrical activity that controls circadianlocomotor behavior by affecting rhythmic release of PDF. The resultssupport an important role of the DN clock neurons in Shaw-mediatedcontrol of circadian behavior.

Email Address for correspondence: james.hodge@bristol.ac.uk

doi:10.1016/j.cbpa.2009.04.313

A10.23Poster Session – Tuesday 30th June 2009Transcriptional control of behavior: Engrailed knockout withRNAi changes cockroach escape trajectories

David Booth (University of Sussex), Bruno Marie (University of PuertoRico), Paolo Domenici (CNR-AMC), Jonathan M. Blagburn (Universityof Puerto Rico), Jonathan P. Bacon (University of Sussex)

The cerci of the cockroach are covered with identified sensoryhairs, which detect air movements. The sensory neurons whichinnervate these hairs synapse with giant interneurons (GIs) in theterminal ganglion which in turn synapse with interneurons and legmotorneurons in thoracic ganglia. This neural circuit mediates theanimal's escape behavior. The transcription factor Engrailed (En) isexpressed only in the medially born sensory neurons, whichsuggested it could work as a positional determinant of sensory

Abstracts / Comparative Biochemistry and Physiology, Part A 153 (2009) S151–S158 S157

neuron identity. Previously, we used RNA interference (RNAi) toabolish En expression, and found that the axonal arborization andsynaptic outputs of an identified En-positive sensory neuron changedso that it came to resemble a nearby En-negative cell, which was itselfunaffected. We thus demonstrated directly that En controls synapticchoice, as well as axon projections.

Is escape behavior affected as a result of this mis-wiring? Adultcockroaches keep each escape unpredictable by running along one ofa set of preferred escape trajectories (ETs) at fixed angles from thedirection of the threatening stimulus. The probability of selecting aparticular ET is influenced by wind direction. Early instar juvenilecockroaches use the same ETs as the adults and are amenable to RNAi.En knockout significantly perturbs the animals' perception ofposterior wind, altering the choice of ETs to one more appropriatefor anterior wind. This is the first time that it has been shown thatknockout of a transcription factor controlling synaptic connectivitycan alter the perception of a directional stimulus.

Email Address for correspondence: jblagburn@gmail.com

doi:10.1016/j.cbpa.2009.04.314

A10.24Poster Session – Tuesday 30th June 2009Costs and benefits of predator induced behaviour in larvae of theurban mosquito (Aedes notoscriptus)

Vincent O. Van Uitregt (The University of Queensland), Robbie S.Wilson (The University of Queensland), Tim Hurst (QueenslandInstitute of Medical Research)

Prey often exhibit behavioural and morphological responses thatconvey greater survival in the presence of predators. The evolutionand maintenance of such responses requires a functional trade-offbetween alternate phenotypes. That is, predator-adapted phenotypesmust be beneficial in the presence of predators but costly in theirabsence. While the cost/benefit trade-off of prey responses seemintuitive, they are often difficult to demonstrate empirically. In thisstudy, we examine the costs and benefits of the behavioural responseof larval mosquitoes Aedes notoscriptus to fish predators. Larval A.notoscriptus reduce activity in the presence of predator chemical cuesfrom firetail gudgeon, Hypseliotris galii. We will test the adaptivebenefits of the behavioural response by entering predator exposedand naïve larvae into predation trials with H. galii. Fitness costs willbe measured by comparing longevity and lifetime fecundity ofpredator exposed to predator naïve females. We predict that larvaeexposed to predator chemical cues throughout development willavoid detection from H. galii for longer, but suffer a shorter adult lifespan and/or reduced lifetime fecundity. We will discuss the findingsof these experiments and the potential use of aqueous predatorchemical cues as control agents of pest mosquitoes.

Email Address for correspondence: v.vanuitregt@uq.edu.au

doi:10.1016/j.cbpa.2009.04.315

A10.25Poster Session – Tuesday 30th June 20093-Dimensional organisation of the antennal lobe of the parasitoidCotesia plutella: A confocal microscopic study

Helga Groll (University of Southampton), Guy M. Poppy (University ofSouthampton), Phil L.Newland(Universityof Southampton), AnaCarolinaRoselino (Université de Toulouse),Martin Giurfa (Université de Toulouse)

Parasitoid wasps rely on the detection of plant volatiles, odourcompounds emitted by a plant after herbivore attack, to track downtheir host for successful reproduction. To determine how olfactoryinformation is processed in their brain, it is necessary to describe theunderlying anatomical brain structures. This study focuses on theantennal lobe of Cotesia plutellae and its glomerular organisation.Brain structures were stained with RH795 and observed by confocalmicroscopy. In addition, a 3D reconstruction of the antennal lobeswas created using AMIRA software.

The average head size of C. plutellae was 645±17 µm×446±14 µm (n=16), with two antennal lobes (AL) each measuring 185±3 µm×139±3 µm×119±3 µm (L×W×D) (n=73). The averagevolume of the AL, including measurements of females and males aswell as both sides valued 311.104 µm3. There was no significantdifference between length, width or depth neither of the antennallobe nor between left and right size and gender.

The glomeruli were located in the outer part of the antennal lobe,around a central area devoid of any apparent glomeruli in the ventralsections. A mean number of 54±7 (n=4) was counted. Glomerularsize was relatively constant throughout the different individuals, withan average diameter of 22×22 µm±0.5 (n=67). In addition toordinary glomeruli, males had 3–4 enlarged ones (52±3×31 µm±2)near the entrance of the antennal nerve,which leads to the speculationof a macroglomerular complex responsible for pheromone detection.

Email Address for correspondence: h.groll@soton.ac.uk

doi:10.1016/j.cbpa.2009.04.316

A10.26Poster Session – Tuesday 30th June 2009Exploring visual motion circuitry in Drosophila with ultravioletlight

Trevor J. Wardill (University of Sheffield), Mikko I. Juusola (Universityof Sheffield)

Compared to higher organisms, the relatively simple andgenetically malleable Drosophila can help us to make sense of motioncoding strategies and visually driven behaviour. We wish to studyhow visual motion-sensitive information is routed to and processedin lobula plate tangential neurons (LPTNs) which express calciumsensitive dyes. For this purpose we have built a 2-photon imagingsetup to record LPTN Ca2+ responses to moving patterns. Given thatphotoreceptor cells are likely to be excited by the Ca2+ fluorescenceand by the high power infrared laser, we have created flies whichhave R1–R6 photoreceptors that are solely ultraviolet (UV) sensitive.Through epifluorescence imaging, we obtained preliminary Ca2+

changes in LPTNs in response to moving UV patterns in vivo.To determine which neurons are involved in motion processing,

we now wish dissect the bottom-up and top-down circuitry to LPTNs.Using a flight simulator, we have shown that the responses of UV-fliesto UV stimuli correspond with wild-type responses to visible stimuli.Next, Ca2+ signals in UV sensitive LPTNs will be recorded andcompared to other transgenic flies. We aim to change the signaling inLPTNs, to understand which synaptic inputs control LPTN activity, byablating or by transgenic expression of light gated channels.Currently, we are working on expressing the light gated channel,Channel Rhodopsin2 (ChR2), to excite neurons. We are yet to see ifChR2 can influence UV-LPTNs. The results will be utilized to buildrealistic mathematical models of motion detection.

Email Address for correspondence: t.wardill@sehf.ac.uk

doi:10.1016/j.cbpa.2009.04.317

Abstracts / Comparative Biochemistry and Physiology, Part A 153 (2009) S151–S158S158