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derived from the ecological relevant sources of this insect species.
This study will be an important contribution in understanding the
olfactory neural mechanisms used by insects to select their hosts
Acknowledgements: Untill now, I do not have any grant/finace to
travel to USA and present my work at AChemS 2012 meeting.
Thats why I applied for travel grant from AChemS. If AChemS
awards a travel grant to me, it will make possible for me to join
AChemS 2012 Meeting.
#P208
POSTER SESSION V:
TRIGEMINAL SYSTEM; BEHAVIOR
AND PSYCHOPHYSICS; ODORANT
RECEPTORS & OLFACTION PERIPHERY
Investigating the structural basis for odorant recognition in an
odorant receptor from the malarial vector,
Anopheles gambiae
David T Hughes, Charles W Luetje
University of Miami, Miller School of Medicine/Molecular and
Cellular Pharmacology Miami, FL, USA
Insect vector-borne diseases are a leading cause of morbidity and
mortality among humans. Insects employ olfaction to find food,
mates and egg-laying sites, making the acquisition of detailed
knowledge of the structure of odorant receptors (ORs) important
for developing more effective insect repellents. To identify
structural features of the odorant binding site of an insect OR, we
examined the odorant responsiveness of two highly homologous
(82% amino acid identity)
Anopheles gambiae
odorant binding
subunits. AgamOr13 and AgamOr15 were expressed in
Xenopus
oocytes (each in combination with AgamOrco) and assayed by
two-electrode voltage clamp electrophysiology. These ORs
displayed distinct odorant specificities, allowing us to develop an
assay based on the ratio of responses of the two receptors to
acetophenone and 4-methylphenol. Each residue in the predicted
transmembrane and extracellular domains of AgamOr15 that
differed from AgamOr13 was mutated to the residue present in
AgamOr13, generating a panel of 34 mutated ORs. Screening this
panel with acetophenone and 4-methylphenol identified A195I as a
mutation that partially shifted the response ratio from that of
AgamOr15 toward that of AgamOr13. Concentration-response
analysis for activation of AgamOr13, AgamOr15 and
AgamOr15,A195I by several odorants confirmed that the A195I
mutation partially shifts the odorant specificity of AgamOr15 to
that of AgamOr13. Our results implicate residue 195, located near
the interface of the predicted second extracellular loop and the
fourth transmembrane helix, as playing a critical role in odorant
activation. We are currently examining residue 195 and its
surrounding area to gain a better understanding of the role of this
region in odorant recognition. Acknowledgements: NIH
RO1DC011091, NIH T32NS007044
#P209
POSTER SESSION V:
TRIGEMINAL SYSTEM; BEHAVIOR
AND PSYCHOPHYSICS; ODORANT
RECEPTORS & OLFACTION PERIPHERY
Characterization and expression of lobster olfactory variants
of ionotropic glutamate receptors
Elizabeth A Corey
1
, Yuriy V Bobkov
1
, Kirill Ukhanov
1
,
Barry W Ache
1,2
1
Whitney Laboratory, Center for Smell and Taste, and McKnight
Brain Institute St Augustine, FL, USA,
2
Depts. of Biology and
Neuroscience, University of Florida Gainesville, FL, USA
The molecular basis of olfactory signal transduction in crustaceans,
a major group of arthropods, is still uncertain, in particular the
nature of the olfactory receptors. We have cloned and analyzed full
length sequences of multiple orthologs of
Drosophila
olfactory
variants of ionotropic glutamate-like receptors (IRs) from the spiny
lobster olfactory organ. Odorant-induced responses from HEK cells
heterologously expressing a combination of two IRs, 1 and 2,
indicate that lobster IRs can form functional odorant receptors and
suggests that, as in insects, they function as heteromers. Unlike the
IR expression pattern in insect olfactory receptor neurons (ORNs),
most, if not all, lobster ORNs express IR1 (ortholog of
Drosophila
IR25a), as confirmed by
in situ
hybridization. IR1 can be further
localized to the transduction compartment (outer dendrites) of the
ORNs by western blotting and immunocytochemistry. While IR1
appears to be a common subunit, other IRs are expressed in very
few ORNs, suggesting specific receptor function. Characterizing
the receptive range of lobster ORNs
in situ
using calcium imaging
shows that single biologically-relevant odorants, e.g., amino acids,
trigger calcium increase in only 0.3-6% ORNs, consistent with the
IR expression pattern. In the context of long-standing evidence for
odorant-activated metabotropic signaling in lobster ORNs,
expression of IRs in the same cells argues that ionotropic and
metabotropic signaling work in concert to effect lobster olfactory
transduction. Acknowledgements: This work was supported by
National Institute on Deafness and Other Communication Disorders
(DC009730, DC005995 and DC001655).
#P210
POSTER SESSION V:
TRIGEMINAL SYSTEM; BEHAVIOR
AND PSYCHOPHYSICS; ODORANT
RECEPTORS & OLFACTION PERIPHERY
Environmentally Regulated Patterns of Olfactory Receptor
mRNA Expression In Pacific Salmon
Andrew H. Dittman
1
, Darran May
2
, Marc A. Johnson
3
1
Northwest Fisheries Science Center, NOAA
Fisheries/Environmental Physiology Program Seattle, WA, USA,
2
University of Washington/School of Aquatic and Fishery Sciences
Seattle, WA, USA,
3
Corvallis Research Laboratory, Oregon
Department of Fish and Wildlife Corvallis, OR, USA
Salmon are well known for their extraordinary homing migrations
from oceanic feeding grounds back to their river of origin to spawn.
These migrations are governed by olfactory discrimination of
homestream odors that juvenile salmon learn (imprint to) prior to
their seaward migrations. Our previous laboratory studies have
suggested that one component of imprinting involves sensitization
of the peripheral olfactory system to specific odorants and up-
regulation of specific odorant receptor (OR) mRNAs. Therefore,
we hypothesized that juvenile salmon exposed to tributary waters
with distinct chemical constituents would display different patterns
of OR expression. To test this hypothesis, we sampled two cohorts
Abstracts | 97
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