Abstracts - Association for Chemoreception Sciences

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P O S T E R S therefore these proteins are not likely to be involved in the discrimination of the ECB and ACB pheromones. This is the first report of multiple PBPs and SNMPs in ECB and ACB. #P163 POSTER SESSION IV: CHEMOSENSORY TRANSDUCTION AND SIGNALING Behavioral and Olfactory Consequences of Slipping Imaginal Discs Between Two Moth Species Seong-Gyu Lee 1 , Kathy R. Poole 2 , Charles E. Linn, Jr. 2 , Neil J. Vickers 1 1 University of Utah Salt Lake City, UT, USA, 2 Cornell University Geneva, NY, USA Two heliothine moths, Heliothis virescens (Hv), and Heliothis sublfexa (Hs), are sympatric species in North America and have a close phylogenetic relationship. Both species use the same chemical substance as a key component of their respective sex pheromone blends and show homology in their pheromonerelated antennal lobe structures, the macroglomerular complex. Despite the significant overlap in the sex pheromone communication systems of these two species, interspecific attraction is avoided by the presence of different behaviorally essential minor pheromone components that can also serve to inhibit males of the other species. Since the olfactory receptor neurons (ORNs) for these minor pheromone components are functional on the male antennae of both species, further processing in the brain must play a critical role in precise pheromonal perception and is reliant upon establishment of the correct wiring connections between ORNs and second-order neurons, the projection neurons (PNs), in the antennal lobe. Forced wiring of heterogeneous ORNs to the indigenous PNs in the brain can be accomplished through interspecific transplants of male antennal imaginal discs. The behavioral responses of male Hv to Hs transplants were assayed in a wind tunnel. Males exhibited a strong preference (56%) for a blend intermediate between Hv and Hs. Electrophysiological recordings from central PNs (N=47) revealed that 32% responded to Z9-14:Ald, as a result of the presence of donor-type antennal ORNs. Both PNs (N=3 out of 5 stains) and ORNs (N=3) exhibited unusual patterns of arborization in the antennal lobe. These results suggest that the predicted spatial relationships between specific peripheral inputs and second-order olfactory neurons were not necessary for successful odor discrimination and behavior to occur. Acknowledgements: Supported by NSF-IOS 0641014 to NJV and CEL. #P164 POSTER SESSION IV: CHEMOSENSORY TRANSDUCTION AND SIGNALING Modulation of pheromone responses by cyclic nucleotides and DAG in antennal trichoid sensilla of the hawkmoth Manduca sexta Andreas Nolte, Christian Flecke, Monika Stengl Universitiy of Kassel Kassel, Germany Manduca sexta males detect sex pheromones with antennal trichoid sensilla. One of the two olfactory receptor neurons which innervate the pheromone-sensitive sensilla always responds to bombykal (BAL), the main pheromone component. The pheromone-dependent signal transduction cascade in insects is still under debate since evidence from different investigators indicated the involvement of several different signal transduction cascades. In tip recordings of pheromone-sensitive trichoid sensilla of the hawkmoth antenna we investigated BAL responses with a non-adapting stimulation protocol (dosage 10 or 1 µg BAL, duration 50 ms, interstimulus interval 5 min) for 3 hours at Zeitgebertimes (ZT) 1-4 (beginning of day = end of activity phase) and 8-11 (rest phase). Perfusion of the sensillar lymph with 100 µM 8bcAMP, a membrane-permeable cAMP analog, increased the sensillar potential (SP) amplitude but did not significantly affect the initial action potential (AP) frequency at ZT 1-4. In accordance, the perfusion with 50 µM forskolin increased the SP amplitude but did also increase the AP frequency at the beginning of the recordings. However, perfusion with 100 µM of a diacylglycerol (DAG) analog inhibited the BAL-dependent AP response and decreased the SP amplitude at ZT 8-11. Our results are consistent with our previously posted hypothesis of pheromone transduction suggesting that BAL activates a phospholipase C-dependent signal transduction cascade, with IP3- dependent activation of Ca 2+ -permeable ion channels. The increase of intracellular Ca 2+ and DAG is suggested to decrease the sensitivity of the signal transduction cascade via activation of protein kinase C. Furthermore, time-dependent sensitization of the pheromone transduction is suggested via octopaminedependent rises of cAMP. Acknowledgements: [Supported via DFG grant STE 531/20-1 to MS] #P165 POSTER SESSION IV: CHEMOSENSORY TRANSDUCTION AND SIGNALING Subunit Contributions to Insect Olfactory Receptor Function Andrew S. Nichols, Charles W. Luetje University of Miami Miller School of Medicine Miami, FL, USA Insect olfactory receptors (ORs) are heteromeric ligand-gated ion channels consisting of at least one common subunit (OR83b in Drosophila) and at least one subunit that confers odorant specificity. We expressed several ORs in Xenopus oocytes to investigate features of the receptor complex and odorant-binding site. First, we examined the sensitivity of Drosophila ORs to inhibition by ruthenium red (RR), a cation channel blocker. Inhibition was non-competitive and the reduction in receptor current amplitude by 50 mM RR varied among the ORs, ranging from 40.6 ± 3.1% inhibition for OR35a/83b to 105.4 ± 7.1% inhibition for OR67a/83b. Since OR83b is common to each receptor, these results suggest the odorant specificity subunit in each receptor contributes to the structure of the site of RR action, the ion pore of the receptor. Next, we found that ORs formed by Drosophila OR35a and an OR83b from either Drosophila melanogaster, Apis mellifera, or Ostrinia nubilalis, displayed highly similar odorant response profiles, suggesting that the OR83b subunit does not contribute to the structure of the odorant-binding site. Finally, a rational expansion of ligand structures based on known activators of Drosophila OR67a/83b enabled us to identify new odorant ligands for this receptor. Comparing the structures of full agonist, partial agonist, and antagonist structures allowed prediction of odorant-binding site requirements, including accommodation of a ring structure and an electronegative functional group on the odorant. Hydrophobic pockets available in either active or inactive conformations of the receptor may provide steric buttressing support and help explain activation or inhibition of the receptor by particular odorants. Acknowledgements: This work was supported by grants from the USDA (2008-35302-18815) and the NIH (DC008119). A.S.N. was supported, in part, by T32 HL07188. 82 | AChemS Abstracts 2010 Abstracts are printed as submitted by the author(s)
#P166 POSTER SESSION IV: CHEMOSENSORY TRANSDUCTION AND SIGNALING Enzymatic conversion of odorants in nasal mucus affects olfactory glomerular activation patterns and odor perception Ayumi Nagashima, Kazushige Touhara The University of Tokyo Tokyo, Japan Odor information is decoded as a combination of olfactory receptors, and thus transformed into discrete spatial patterns of olfactory glomerular activity, which reflect differences in the quality of odorants. We previously found that there were differences between the ligand specificity of an olfactory receptor in vitro and of its corresponding glomerulus in vivo for some odorants. These observations led us to hypothesize that there existed pre-receptor events that affected the local concentration of a given odorant in the nasal mucus, which causes the apparent specificity differences. Here we show that odorants with functional groups such as aldehyde and ester are targets of metabolic enzymes secreted in the mucus, resulting in the conversion to corresponding acid and alcohol. Using in vivo imaging, comparison between the activation patterns in the olfactory bulb in the presence or absence of an enzyme inhibitor in the mucus suggested that the spatial glomerular activity pattern elicited by an enzyme-targeted odorant, acetyl isoeugenol, for example, was not purely the representation of the receptor code for acetyl isoeugenol but for the mixture of acetyl isoeugenol and the enzymatically converted odorant, isoeugenol. Importantly, olfactory discrimination tests revealed that the mice behaviorally trained to associate acetyl isoeugenol to sugar rewards could not discriminate acetyl isoeugenol after the treatment with the enzyme inhibitor, suggesting that they perceive acetyl isoeugenol as a different odor from the odor of acetyl isogenol during training. These results reveal that the enzymatic conversion of odorants in the nasal mucus appear to affect the odor quality at the level of perception, shedding light on a unappreciated role of nasal mucosal enzymes in odor sensation. #P167 POSTER SESSION IV: CHEMOSENSORY TRANSDUCTION AND SIGNALING PI3K-dependent Inhibitory Signaling in Mammalian Olfactory Receptor Neurons Kirill Ukhanov 1 , Daniela Brunert 1 , Barry W. Ache 1,2 1 Whitney Laboratory, Center for Smell and Taste, and McKnight Brain Institute Gainesville, FL, USA, 2 Depts. of Biology and Neuroscience Gainesville, FL, USA with lilial-dependent inhibition of the response to bourgeonal, suggesting the finding can generalize to other odorant pairs. Collectively, our findings raise the interesting specter that either PI3K constitutively modulates OR binding, or ligand-directed binding to the OR targets both cyclic nucleotide and phosphoinositide signaling in mammalian ORNs. Acknowledgements: NIH NIDCD DC001655, DC005995 #P168 POSTER SESSION IV: CHEMOSENSORY TRANSDUCTION AND SIGNALING Functional implication of PI3K beta and gamma in rodent olfaction Daniela Brunert 1 , Katharina Klasen 1 , Elizabeth A. Corey 1 , Kirill Ukhanov 1 , Barry W. Ache 1,2 1 Whitney Laboratory, Center for Smell and Taste and McKnight Brain Institute, University of Florida Gainesville, FL, USA, 2 Depts. of Biology and Neuroscience, University of Florida Gainesville, FL, USA Phosphatidylinositol 3-kinase (PI3K)-dependent signaling couples to receptors for many different ligands in diverse cellular systems, including rat olfactory receptor neurons (ORNs). Here, we generalize the latter finding to mice by showing PI3K-dependent inhibition of the calcium response of mouse ORNs to odorant stimulation as well as odorant-dependent increase in phosphoinositides in the mouse olfactory epithelium (OE) measured in ELISA. Like rat ORNs, mouse ORNs express two known GPCR -activated isoforms of PI3K, PI3Kb and PI3Kg. Both isoforms are expressed in many, if not most ORNs. Isoform specific blockers, TGX-221 (PI3Kb) and AS252424 (PI3Kg), are equally effective in reducing both the odorant dependent rise in phosphoinositides as well as the PI3K-dependent inhibition of the calcium response to odorants. ORNs from transgenic mice deficient for PI3Kg show a residual response to pan-specific PI3K blockers, suggesting that PI3Kg plays a role but is not exclusively responsible for PI3K mediated signaling in murine ORNs. Collectively, our results suggest that PI3Kb and g may have redundant function in rodent ORNs, as known to occur in bone marrow-derived macrophages and blood platelets. Further studies using mice deficient for PI3Kb alone and double deficient mutants are targeted to help resolve the relative roles of the two isoforms of PI3K in rodent olfaction. Acknowledgements: Supported by the National Institute on Deafness and Other Communication Disorders (DC001655, DC005995) and a Feodor Lynen Research Fellowship from the Alexander von Humboldt Foundation P O S T E R S Phosphoinositide-3-kinase (PI3K)-dependent signaling can modulate the response of mammalian olfactory receptor neurons (ORNs) to complex odorants. We now extend this observation to single odorant pairs. Citral inhibited the response to octanol in 13 of 91 octanol-responsive acutely dissociated rat ORNs measured with calcium imaging. Citral itself was not an effective ligand for these ORNs while inhibiting the response to octanol in a concentration-dependent manner. Blocking PI3K relieved the citral-dependent inhibition but had no effect on the response to octanol. Citral also inhibited in a PI3K- and concentrationdependent manner the response to IBMX/Forskolin (IF) in about 1% of IF-responsive ORNs. We argue that citral affects PI3Kdependent signaling being otherwise weak agonist in these ORNs. The PI3K-dependent enhanced response to citral was blocked by MDL12330A and SQ22536, implicating cyclic nucleotidedependent signaling in the output. Similar results were obtained #P169 POSTER SESSION IV: CHEMOSENSORY TRANSDUCTION AND SIGNALING Regulation Of Sodium Calcium Exchanger (Ncx) Activity By Calmodulin Or Omp In The Olfactory Signaling Transduction Cascade Manoj Tyagi, Frank L Margolis Anatomy and Neurobiology, University of Maryland Baltimore Baltimore, MD, USA Dynamic changes in the concentrations of Na + and Ca 2+ modulate signaling in the olfactory sensory neuron (OSN). Na/Ca exchanger (NCX) activity plays an important role in this process and its activity is modulated by different proteins. We reported reduced efficiency of Ca2+ extrusion by NCX in Abstracts are printed as submitted by the author(s) Abstracts | 83
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AChemS Association for Chemorecepti
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AChemS Association for Chemorecepti
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We are pleased to announce that sev
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#1 GIVAUDAN LECTURE Normal and Canc
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and against delta ENaC is being pur
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#13 SYMPOSIUM - GENETICS OF HUMAN O
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#19 SYMPOSIUM - CILIA, SENSORY DYSF
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#26 PLATFORM PRESENTATIONS - POLAK
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esponse selectivity for both OSNs a
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elicit glucagon-like peptide-1 (GLP
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contrast, changing the concentratio
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of OBPs, we have systematically sup
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whereas mouse and joystick reaction
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POSTER PRESENTATIONS #P1 POSTER SES
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PROP strips and PROP solutions. PAV
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possibly suggesting non-apoptotic m
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#P325 POSTER SESSION VII: OLFACTORY
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of 7/10, and causing eyes to water
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showed that N1/P2 latencies were lo
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differentiated patients with AD (M=
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pleasantness 3)of mixtures (A,B), A
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Index Aarts, H - P328 Abe, K - P88,
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Haase, L - P3, P4, P29, P355 Haddad
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Murata, Y - P272 Murphy, C - P3, P4
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Veldhuizen, M - P7, P24, P25, P242,
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Registration 7:30 am to 1:00 pm, 6:
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See you next year! AChemS 33rd Annu
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