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14 | AChemS Abstracts 2012
Abstracts are printed as submitted by the author(s)
chemical stimuli. We plan experimental tests of DMS. We
hypothesize that whales, like seabirds, converged upon olfaction
and use DMS to locate dense swarms of patchy zooplankton prey.
Other patterns support this notion. Within whales, baleen species
that specialize on zooplankton (Suborder Mysticeti) have more
notable olfactory systems than toothed whales (Odonticeti).
A similar diet-based dichotomy occurs in seabirds between
tubenoses (Order Procellariiformes) and Charadriiformes. Applying
general principles of avian chemosensory behavior may help us
gain new insight into the feeding biology of whales. The approach
promises to yield information about an entirely overlooked mode of
perception in whale biology applicable to other key behaviors, such
as migration and social interactions. Acknowledgements: Alaska
Whale Foundation, Juneau Lighthouse Association
#14
PLATFORM PRESENTATIONS:
OLFACTION
Chemosensory Functions for Degenerin/Epithelial
Sodium Channels
Yehuda Ben-Shahar, Xiaoling Gu
Washington University in St. Louis/ Biology St. Louis, MO, USA
Asthma represents a major but poorly understood health concern.
In asthmatic individuals, noninfectious stimuli such as cold air or
strong odors can often induce and exacerbate disease conditions,
but the cellular and molecular mechanisms underlying these
pathologies are unknown. We have identified a rare population of
cells in the human airway epithelium that show the morphology of
immune-related dendritic cells but express members of the human
olfactory receptor family. Based on these findings, we tested the
novel hypothesis that direct activation of olfactory sensory
pathways in specialized non-neuronal olfactory sensory cells
(
olf
DCs) mediates asthma-related hyperreactivity via immune-
independent pathways. We further hypothesize that the sensory
activation of
olf
DCs leads to hyperreactivity via a local release of
5-HT, which mediates airway constriction. We discovered that
olf
DCs incidence was associated with airway disease states in both
COPD vs. normal humans as well as in primate models of asthma.
Furthermore, preliminary data suggest that stimulating primary
human airway cultures with strong odors can lead to release of
5-HT, which may provide a mechanistic explanation for odor
sensitivities in individuals suffering from airway diseases.
#15
PLATFORM PRESENTATIONS:
OLFACTION
Computational Assessments of Olfactory Receptor
Odorant Interactions
Chiquito J Crasto, Peter C Lai
University of Alabama at Birmingham, Department of Genetics
Birmingham, AL, USA
Computational methods have allowed a glimpse into the
mechanisms of the first step leading to olfaction. Odor molecules
follow a path from outside the nostrils through the mucus
membrane, bind, interact with and excite the olfactory receptor,
thereby facilitating a signal transduction process that leads to our
sense of smell. We have performed rigorous computational
assessments of several experimentally (functionally) well
characterized olfactory receptors: rat OR I7, mouse ORs S79 and
S86 (part of a comprehensive combinatorial functional analysis),
human ORs 17-209 (OR1G1) and the “functional pseudogene17-
210 (OR1E3P). Our computational methodology includes:
creating the protein model, computationally binding an odorant
(experimentally shown to bind the receptor) into the OR model
binding region, simulating an aqueous environment and a lipid
bilayer representing the plasma membrane, and performing long-
duration molecular dynamics simulation studies of the odorant
behavior in the OR binding pocket. Our results have, all firsts for
the field, allowed us to view in real time entry and exit paths from
and to the binding region of the OR. We have also observed how
specific residues contribute to odorant binding—a combination of
van der Waals and electrostatic interactions—over the course of a
simulation. We have observed the involvement of specific amino
acid residues from the inter-helical loops, an advancement over
traditional static docking methods. We have been able to show a
strong correlation between excitation of an OR by an odorant and
preferential binding between two binding regions of an OR. It has
long been surmised that OR excitation proceeds from a structural
change following OR-binding. We have been able to pinpoint this
structural excitation in the OR. Acknowledgements: NIH (NIDCD)
(1R21DC011068-01)
#16
PLATFORM PRESENTATIONS:
OLFACTION
Fasting induced-changes in the spatiotemporal representation
of odors in the main olfactory bulb
Mounir Bendahmane
1,2
, Claire Martin
1
, Monique Caillol
2
,
Christine Baly
2
, Hirac Gurden
1
1
Imagerie et Modélisation en Neurobiologie et Cancérologie
(IMNC), UMR 8165, Universités Paris 7 et 11 Orsay, F-91405,
France,
2
Unité de Neurobiologie de l’Olfaction et Modélisation
en Imagerie (NOeMI) Jouy en Josas, F-78350, France
Odors are major indicators of food palatability and essential for
food detection and feeding behavior. However, the nutritional
impact on the representation of odors in the olfactory system is
elusive. Therefore we studied the effects of fasting on the
spatiotemporal activity in the main Olfactory Bulb (OB), a
structure supporting the first step of odor coding in the brain.
We tested odor responses of the OB in 17 hours-fasted rats
compared to ad libitum-fed rats. We used two olfactory stimuli:
the first one (almond aroma odor) is associated to food since it is
incorporated to a homemade cake that rats are used to eat and are
excited about; the second is the pure odorant hexanal which is
neutral. We probed both types of coding (spatial and temporal) at
O R A L A B S T R A C T S