Abstracts - Association for Chemoreception Sciences

P O S T E R S
been isolated in P. shermani. The DNA sequences clustered into
3 subfamilies that are less than 80% similar in sequence
identity. In situ hybridization (ISH) using RNA probes revealed
2 different patterns of V2R RNA expression in the VNO. In one
pattern, the number of cells labeled by the RNA probe was
positively correlated to the volume of the VNO. In other words,
the density of cells expressing a particular class of V2R was similar
across individuals. In the other pattern, the number of labeled
cells was unrelated to the volume of the VNO. In this case,
individuals with a larger VNO had proportionally fewer labeled
cells than did individuals with a smaller VNO. Thus, individual
differences in V2R expression may contribute to differences in
sensory function. Since males typically have a larger VNO than
females, both in absolute size and relative to body size, this may
translate into sex differences in responses to sensory information.
Acknowledgements: NSF IOS-0818554 to LDH, NSF IOS-
0808589 to KMK and LDH, NSF predoctoral fellowship
to KMK.
#P157 POSTER SESSION IV: CHEMOSENSORY
TRANSDUCTION AND SIGNALING
Molecular characterization and localization of olfactoryspecific
ionotropic glutamate receptors in lobster olfactory
receptor neurons
Elizabeth A Corey 1 , Yuriy Bobkov 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 olfaction in crustaceans, a major group of
arthropods, is still uncertain. While there is accumulating evidence
that G protein activation of metabotropic signaling pathways is
involved in crustacean olfactory signal transduction, a lobster
olfactory-specific ionotropic glutamate receptor, OET07, appears
to be an ortholog of the recently discovered Drosophila olfactory
variant of ionotropic glutamate receptors (IRs). These results
suggest that crustacean olfactory transduction mechanisms are at
least in part similar to those of insects. As a first step towards
understanding the role of IR-mediated signaling in crustacean
olfaction, we have begun to characterize the expression of lobster
olfactory IRs. We have cloned two full length lobster IR
orthologs, including that of OET07, as well as partial sequences
from other additional potential IRs, and demonstrated that all of
the putative IRs can be detected in lobster olfactory tissue by
RT-PCR. The lobster ortholog of OET07 can be detected in most,
if not all, olfactory receptor neurons by in situ hybridization, and
can be localized to the transduction compartment (outer
dendrites) by western blot and immunocytochemistry. These
results support a role for IR-mediated signaling in the lobster
olfactory transduction mechanism. Using heterologous
expression, we are currently attempting to determine whether the
lobster IR orthologs can function as ionotropic
receptors. Acknowledgements: Supported by grants from the
National Institute on Deafness and Other Communication
Disorders.
#P158 POSTER SESSION IV: CHEMOSENSORY
TRANSDUCTION AND SIGNALING
Measuring Ensemble Activity in Lobster ORNs through
Calcium Imaging
Yuriy V. Bobkov 1 , Kirill Y. Ukhanov 1 , Ill Park 3 , Jose C. Principe 3 ,
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, 3 Dept. of Electrical and Computer
Engineering, University of Florida Gainesville, FL, USA
Lobster ORNs can be imaged in the olfactory organ in situ,
thereby maintaining the normal polarity of the cells and the ionic
environment of the olfactory cilia. The preparation gives
simultaneous access to hundreds of ORNs that are viable for
hours, thereby allowing rigorous characterization of their steadystate
and dynamic properties. Odorants change the level of
cytoplasmic Ca 2+ in a dose-dependent manner in ORNs loaded
with Ca 2+ -sensitive indicator either through bath application or
via a patch electrode. The kinetics and amplitude of the odorantevoked
Ca 2+ signal correlate with the excitatory inward current,
the degree of membrane depolarization, and the number of
evoked action potentials, thereby establishing the physiological
relevance of the Ca 2+ signal. Spontaneous periodic Ca 2+ transients
in many ORNs correlate with spontaneous bursts of action
potentials measured in single cells in the same cluster. We are
using signal processing algorithms to analyze the level of
correlated activity between these ORNs and the extent to which
periodic calcium oscillations in different ORNs are synchronized
by common intermittent excitatory input to test the predictions of
our computational model for ensemble burst coding in these cells
and the potential relevance of bursting input to olfactory scene
analysis. Acknowledgements: Supported by the NIDCD
(DC001655, DC005995)
#P159 POSTER SESSION IV: CHEMOSENSORY
TRANSDUCTION AND SIGNALING
Ca Imaging of Response Properties of Olfactory Receptor
Neurons of Spiny Lobsters, Panulirus argus
Manfred Schmidt, Tizeta Tadesse, Charles D Derby
Neuroscience Institute, Georgia State University Atlanta, GA,
USA
The spiny lobster, Panulirus argus, is an established model for
studying olfaction. Its olfactory organ consists of tufts of
specialized sensilla – aesthetascs – on the lateral flagella of the
antennules with each aesthetasc containing a cluster of > 300
olfactory receptor neurons (ORNs). Although transduction
mechanisms in aesthetasc ORNs have been analyzed in detail with
patch clamp electrophysiology (Ache and Young, Neuron 48:417-
430, 2005), very little is known about their basic response
properties such as sensitivity and spectral tuning. To study these
questions, we established Ca imaging of ORN responses in an in
vitro ‘slice’ preparation similar to that used for patch clamp
recordings. Short segments of lateral flagella were incubated in the
Ca indicator Fluo-4 AM, mounted in an experimental chamber
perfused with Panulirus saline, and imaged with an
epifluorescence microscope equipped with monochromator and
CCD camera. Our initial results showed that within each cluster
several ORNs took up Fluo-4 and responded with a robust
increase in fluorescence to global depolarization with high K +
80 | AChemS Abstracts 2010 Abstracts are printed as submitted by the author(s)