genetic dissection of associative and non-associative learning in c. elegans

A10.311:00 Tuesday 30th June 2009Peptidergic neuromodulation in olfactory circuits of the Droso-phila brain

Dick R. Nässel (Stockholm University), Mikael A. Carlsson (StockholmUniversity), Asa M. Winther (Stockholm University)

Neuropeptides are likely to be important in neuronal modulationand plasticity. Most of the neuropeptide genes identified in Drosophilaare expressed in the brain and many of the peptide products of thesegenes are produced by central interneurons. Although there is a largenumberof different neuropeptides in theDrosophilabrain, relatively fewpeptides have been detected in each neuronal subsystem (neuropilregion). As anexample, the olfactory neuronsof the antennal lobes seemtoutilizepeptide products of only three genes and themushroombodiesthat of one gene. Neuropeptide signaling in the olfactory system istractable for functional analysis by means of targeted Gal4-UASmediated interference, and we can benefit from great advances thathave been made in understanding the processing of odor information.We approach the system both at the level of the first synapses in theantennal lobes and more centrally in the mushroom bodies. Twopeptides, and their receptors, will be discussed here, short neuropeptideF (sNPF) and Drosophila tachykinin (DTK). A subset or the olfactoryreceptor neurons (ORNs) of antennae and maxillary palps expressessNPF, and DTK signaling is seen in a feedback from local antennal lobeinterneurons ontoORNs. The possible roles of thesepeptides in olfactionwill be discussed. Furthermore, we have found that most of the intrinsicneuronsof themushroombodies, theKenyoncells, express sNPFand thefunctional consequences of these are under study.

Email Address for correspondence: [email protected]

doi:10.1016/j.cbpa.2009.04.294

A10.411:30 Tuesday 30th June 2009Glutamate uptake system in Lymnaea stagnalis

Etsuro Ito (Tokushima Bunri University), Dai Hatakeyama (TokushimaBunri University), Koichi Mita (Tokushima Bunri University), SuguruKobayashi (Tokushima Bunri University), László Hiripi (BalatonLimnological Research Institute), Károly Elekes (Balaton LimnologicalResearch Institute)

A series of previous data derived by the aspects of glutamate andits receptors suggested that glutamate is used as a neurotransmitterfor the generation of feeding rhythm in the pond snail Lymnaeastagnalis. The uptake mechanism of glutamate, however, is not yetknown, and so in the present study we characterized glutamatetransporters and examined the functions of these transporters in thefeeding circuits of Lymnaea central nervous system (CNS). First,measuring the accumulation of 3H-labeled glutamate showed thepresence of glutamate transport systems with different types ofglutamate transporters, excitatory amino acid transporter (EAAT) andvesicular glutamate transporter (VGluT), in Lymnaea CNS. The highestaccumulation rate was measured in the buccal ganglia, suggesting theinvolvement of glutamate transport systems in the feeding behavior.Second, we succeeded in cloning 2 types of glutamate transporter ofLymnaea, LymEAAT and LymVGluT, and showed that the functionaldomains in both types of transporters are well conserved incomparison to these amino acid sequences with those of mammalianEAATs and VGluTs. Third, in situ hybridization showed that themRNAs of LymEAAT and LymVGluT are transcribed in the major

feeding motoneurons in the buccal ganglia. Finally, the changes infiring patterns of the feeding motoneurons, which have glutamatergicinputs, by inhibition of LymEAAT were similar to those by stimulatingwith glutamate. These results showed that glutamate uptake systemsare located in the feeding circuits and they are required for thegeneration of feeding rhythm of Lymnaea.


doi:10.1016/j.cbpa.2009.04.295

A10.511:50 Tuesday 30th June 2009Comparison of aversive and reward one-trial classical condition-ing in the Lymnaea feeding system

Ildiko Kemenes (University of Sussex), Michael O'Shea (University ofSussex), Paul R. Benjamin (University of Sussex)

We previously developed a one-trial reward classical conditioningparadigm using amyl-acetate as the conditioned stimulus (CS) andsucrose as the unconditioned stimulus (US), to study the electrical andmolecular changes underlying long-term memory formation in thefeeding system of the pond snail Lymnaea. Here, we compare thefeatures of one-trial reward conditioning with an alternative aversiveconditioning paradigmwhere quinine was used as the US while the CSwas the same (amyl acetate) as in reward conditioning. Here, a singlepairingof CSandUS led to aversive conditioning. Anelectrophysiologicalcorrelate of both types of conditioning was measured in semi-intactpreparations. The same CS caused excitation or inhibition depending onthe type of the training. The source of the inhibition in case of aversiveconditioningappears tobe innon-feedingganglia in the rest of the brain.Our results indicate that the same CS can trigger alternative responsesdepending on the type of training (US). These two types of responsesinvolve different pathways within the CNS.

The sensitivity of the aversive and appetitive memory trace to NO,dopamine and octopamine blockers was also studied. We establishedthat while NO and dopamine are important in the development of along-term appetitive memory trace at an early stage after condition-ing they do not play a role in aversive memory formation.Octopamine, on the other hand is not needed for appetitive memoryformation, but seems to be the key transmitter needed shortly afteraversive training.


doi:10.1016/j.cbpa.2009.04.296

A10.613:30 Tuesday 30th June 2009Genetic dissection of associative and non-associative learningin C. elegans

Catharine H. Rankin (University of British Columbia)

Caenorhabditis elegans are able to show a variety of forms ofassociative and non-associative learning as well as long-termmemory for mechanosensory habituation. Our data suggests thatthere are multiple mechanisms mediating short-term habituation,and that there are several different forms of lasting memory. Proteinsynthesis dependent long-term memory for habituation in C. elegansis produced by spaced, but not massed training protocols. This long-term memory is mediated by CREB dependent down-regulation of a

Abstracts / Comparative Biochemistry and Physiology, Part A 153 (2009) S151–S158S152

http://dx.doi.org/10.1016/j.cbpa.2009.04.294



Kainate/AMPA type glutamate receptor subunit, glr-1. Long-termhabituation training is hypothesized to lead not to a change in thenumber of synapses, but to a decrease in the average size of synapses.A second, protein synthesis independent form of lasting memory canbe seen 12 h after massed training. This memory is dependent on anincrease in the release of an inhibitory neuropeptide from the sensoryneurons. We have also shown associative learning in the form ofcontext dependent habituation. In this procedure animals that aretrained and tested in the same environment (chemosensory cue)show greater memory for training than worms trained and tested indifferent environments. We are using this paradigm to differentiategenes involved in associative and non-associative learning. We havefound that a C. elegans homologue of AMPA/Kainate type glutamatereceptors is critical for long-term memory for habituation, and that ahomologue of NMDA-type glutamate receptors is critical for contextconditioning. These data support the hypothesis that many mechan-isms and characteristics of memory are highly conserved acrossevolution.


doi:10.1016/j.cbpa.2009.04.297

A10.714:30 Tuesday 30th June 2009Synaptic organization and function in a single behaviorallyrelevant neuron

JannW. Gardner (University of Utah), Andres Villu Maricq (Universityof Utah), David M. Madsen (University of Utah), Frédéric Hörndli(University of Utah), Jerry E. Mellem (University of Utah), Craig S.Walker (University of Utah)

Many animals can associate temperature with favorable environ-mental resources and thermotax to the most favorable temperature.However, the neural mechanisms that regulate thermotaxis are notwell understood. In the nematode C. elegans, a small neural circuitconsisting of sensory neurons and interneurons detects temperatureand directs movement. Our goal is to understand how this simplecircuit functions at the level of individual synapses and receptors. Acritical element in the thermotaxis circuit is the pair of RIAinterneurons, which appear to have a major integrating function indetermining the appropriate motor output. We have discovered thatglutamatergic signaling mediated by the kainate class of ionotropicglutamate receptors (iGluRs) is required for thermotaxis. Thesekainate iGluRs are exclusively expressed in RIA, which receive inputsfrom the thermal sensing circuitry. Deletion mutations in kainatereceptor subunits eliminate a subset of the glutamate-gated current inRIA and modify the thermotactic behavior. In contrast, no change inthis behavior is observed inmutants that lack AMPA-class iGluRs. Thus,a single neuron differentially localizes classes of iGluRs to subserveinformation processing and control of behavior.


doi:10.1016/j.cbpa.2009.04.298

A10.815:40 Tuesday 30th June 2009Hangovers, hairy dogs and worms: Modeling alcohol inducedplasticity in C. elegans

Lindy Holden-Dye (University of Southampton), James Dillon (Uni-versity of Southampton), Philippa Mitchell (University of South-

ampton), Yiannis Andrianakis (University of Southampton), RichardMould (University of Southampton), Steven Glautier (University ofSouthampton), Christopher James (Universityof Southampton), VincentO'Connor (University of Southampton)

The ability of neural systems to undergo homeostatic adaptation inresponse to chronic ethanol exposure is well-documented in bothinvertebrates and mammals. Unpicking the precise molecular andcellular determinants of the adaptive responses to ethanol isconfounded by the interaction of ethanol with multiple neuralsignalling pathways. Here we define a paradigm in which the abilityof the simple genetically tractable animal C. elegans to perform anintegrative behavioural task, navigation towards food, provides a read-out of distinct ethanol-induced behavioural states. In particular weshow that chronic exposure to, and subsequent withdrawal from,ethanol impairs navigational performance. Evidence that this is due toa direct neuroadaptive response to ethanol is provided by theobservation that the behaviour in ethanol withdrawal is alleviated bya sub-intoxicating dose of ethanol. This ‘withdrawal relief’ effectsubstantiates the use of this behavioural paradigm to define neuralsubstrates of ethanol-induced plasticity.

We acknowledge the financial support of the Biotechnology andBiological Sciences Research Council, UK and the CGC for provision ofstrains.


doi:10.1016/j.cbpa.2009.04.299

A10.916:20 Tuesday 30th June 2009Cockroaches keep predators guessing by using preferred escapetrajectories

Paolo Domenici (CNR-AMCIMC, Italy), David Booth (University ofSussex, UK), Jonathan M. Blagburn (University of Puerto Rico),Jonathan P. Bacon (University of Sussex, UK)

Anti-predator behaviour is vital for most animals, and calls foraccurate timing and swift motion. Whereas fast reaction times andpredictable, context-dependent, escape-initiation distances arecommon features of most escape systems, previous work hashighlighted the need for unpredictability in escape directions, inorder to prevent predators from learning a repeated, fixed pattern.Ultimate unpredictability would result from random escape trajec-tories. Although this strategy would deny any predictive power tothe predator, it would also result in some escape trajectoriestowards the threat. Previous work has shown that escape trajec-tories are in fact generally directed away from the threat, althoughwith a high variability. However, the rules governing this variabilityare largely unknown.

Here, we demonstrate that individual cockroaches (Periplanetaamericana, a much-studied model prey species) keep each escapeunpredictable by running along one of a set of preferred trajectoriesat fixed angles from the direction of the threatening stimulus. Theseresults provide a new paradigm for understanding the behavioralstrategies for escape responses, underscoring the need to revisit theneural mechanisms controlling escape directions in the cockroachand similar animal models, and the evolutionary forces drivingunpredictable, or ‘protean’, anti-predator behaviour.


doi:10.1016/j.cbpa.2009.04.300

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genetic dissection of associative and non-associative learning in c. elegans

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