1 1 Symposium Chemosensory Receptors Satellite DEVELOPMENT ...

349 Poster Chemosensory Molecular Genetics andVNO/PheromoneEXPANSION OF THE HONEY BEE ODORANT RECEPTORFAMILY SUPPORTS THE 1 NEURON/1 OR/1 GLOMERULUSMODEL OF INSECT OLFACTIONRobertson H.M. 1 , Wanner K. 1 1 Entomology, University of Illinois atUrbana-Champaign, Champaign, ILWe have built 170 odorant receptor (Or) gene models in the drafthoney bee genome sequence, of which about 10 are pseudogenes. Theseinclude a massive subfamily expansion of 157 receptors, including 60 ina perfect tandem array. This number of roughly 160 functional Or genesmatches well the number of glomeruli in the bee antennal lobe atroughly 160-165. This match supports the 1 neuron/1 Or/1 glomerulusmodel of insect olfaction. In stark contrast, bees encode just 10gustatory receptors (Grs), which represent most of the major Grlineages in insects, but with no subfamily expansions. Thus bees haveexpanded their Or repertoire significantly relative to flies (60-80 Ors),perhaps to meet their needs for floral odor recognition in addition totheir use of several pheromones in social communication and chemicalsfor kin recognition. The lack of Gr family expansion relative to the flies(68-76 Grs) might reflect their mutualistic relationship with plants, thusnot needing to detect toxic plant chemicals, as well as their nursing oflarval bees which do not need to forage. Bees might also employ Ors asgustatory receptors when antennating each other and other objects.350 Poster Chemosensory Molecular Genetics andVNO/PheromoneDIVERSITY AND CONSERVATION OF LEPIDOPTERANOLFACTORY RECEPTORSAnderson A.R. 1 , Jordan M. 2 , Newcomb R. 2 , Trowell S. 1 1 Entomology,CSIRO, Acton, Australian Capital Territory, Australia; 2 GeneTechnologies, HortResearch, Auckland, New ZealandThe ability of organisms to detect and discriminate between manyodours is pivotal to their survival and primarily due to the olfactorysystem. In vertebrates, C.elegans and Drosophila, odorant receptors(OR´s) provide the molecular basis for odor coding and belong to thelarge super family of G-Protein Coupled Receptors. In insects, OR´s areextremely diverse across orders and species with the exception of theOr83b homologues. The Or83b receptor exhibits a high level ofsequence conservation across four orders and appears to be required forlocalizing other OR proteins to the dendrites of olfactory neurons. Thegenomes of Drosophila, Anopheles gambiae and Bombyx mori, the silkmoth, are now available for sequence mining. We are mining thegenome of Bombyx for homologues of the known ORs of Drosophilaand Heliothis virescens and also for homologues of novel ORs isolatedexperimentally from other lepidopteran species (Jordan and Newcomb,unpublished). We are particulary interested in the extent to whichspecific OR sequences are conserved within an order or other taxon andthe functional significance of such sequence conservation. We are usingdegenerate RT-PCR to probe for conservation of OR sequences in sixlepidopteran species, besides Bombyx, representing another fivelepidopteran families. RNA in-situ hybridisation and functional studieswill help us to elucidate the functions of the ORs we have identified.351 Poster Chemosensory Molecular Genetics andVNO/PheromoneFEMALE SPECIFIC ODORANT RECEPTORS EXPRESSED INTHE ADULT ANTENNAE OF THE SILKMOTH, BOMBYXMORIWanner K.W. 1 , Anderson A.R. 2 , Trowell S. 3 , Theilmann D. 4 , RobertsonH.M. 1 , Newcomb R. 5 1 Entomology, University of Illinois at Urbana-Champaign, Urbana, IL; 2 School of Biological Sciences, MonashUniversity, Victoria, Victoria, Australia; 3 Entomology, CSIRO, Acton,Australian Capital Territory, Australia; 4 PARC, Agriculture and Agri-Food Canada, Summerland, British Columbia, Canada; 5 GeneTechnologies, HortResearch, Auckland, New ZealandOlfaction plays an important role in the life history of insects,including key pest behaviors such as host selection and oviposition byfemale moths. We identified 54 novel scaffolds encoding complete orpartial odorant receptors (Or) from the recently sequenced silkmoth(Bombyx mori, Bm) genome. This brings the total number of knownBmOrs to 60, a number that corresponds well to the approximate 61glomeruli in the silkmoth antennal lobe, supporting the one odorantreceptor- one sensory neuron- one glomerulus model of insect olfaction.Each Or was screened for female biased expression patterns in adultmoth antennae using quantitative PCR. Several Ors were moderatelyfemale biased, 3-10 times more abundant in female as compared to maleantennae. Three were of particular interest since their relativeabundance in female antennae was much greater, 40 to 800 times that ofmale antennae. The complete cDNA sequences of the three femalespecific Ors are currently being cloned and attempts to characterizetheir ligand binding specificity are underway. This work represents animportant step towards elucidating female specific olfactory pathwaysthat are involved in key female specific behaviors in lepidopteranmoths.352 Poster Chemosensory Molecular Genetics andVNO/PheromoneSHIFTS IN THE USE OF TWO ALDEHYDES AND THEEVOLUTION OF OLFACTORY COMMUNICATION INHELIOTHINE MOTHSHillier K.N. 1 , Hamilton J. 2 , Horovitz J. 2 , Vickers N. 1 , Gould F.L. 21 Biology, University of Utah, Salt Lake City, UT; 2 Entomology, NorthCarolina State University, Raleigh, NCIn heliothine moths, a cosmopolitan group with extant species on 6continents, divergence in olfactory communication is often manifestedby shifts in the use of two secondary, but essential compounds in thepheromone blend: (Z)-9-tetradecenal (Z9-14:Ald) and (Z)-9-hexadecenal (Z9-16:Ald). In several species, Z9-14:Ald has becomeantagonistic to male behavior and in two Helicoverpa species the blendshave shifted to the extreme inasmuch as Z9-16:Ald has become theprimary pheromone component. We seek to understand the geneticcomplexity underlying the shift in male preference for either of thesetwo odorants in the Heliothis virescens/Heliothis subflexa system wheremales have diverged to utilize Z9-14:Ald or Z9-16:Ald respectively.Through behavioral and olfactory studies of hybrid and backcross malesof interbred H. virescens and H. subflexa, we have shown that thepreference for either Z9-14:Ald or Z9-16:Ald is associated with achange in the specificity of peripheral olfactory receptor neurons. QTLanalysis from behaviorally phenotyped backcross males indicated thatmost variation in this character was explained by a single chromosome.Subsequent mapping revealed that the candidate pheromone receptorgene, HR14 (Krieger et al., 2004) also mapped to this samechromosome. In the current studies we report on the behavioral andolfactory phenotypes and genotypes of males generated by recurrentbackcrossing to H. virescens. In these males a single H. subflexachromosome was isolated in an H. virescens background. The resultsindicate that a major gene may play a fundamental role in maleolfactory preference and pheromone blend evolution in heliothine mothspecies. Supported by NSF, IOB-0416861 to NJV.88