Abstracts - Association for Chemoreception Sciences

#P192 POSTER SESSION IV:
CHEMICAL SIGNALING AND BEHAVIOR;
ANIMAL BEHAVIOR/PSYCHOPHYSICS;
CHEMOSENSATION AND METABOLISM;
VOMERONSASAL AND CHEMICAL
COMMUNICATION
#P193 POSTER SESSION IV:
CHEMICAL SIGNALING AND BEHAVIOR;
ANIMAL BEHAVIOR/PSYCHOPHYSICS;
CHEMOSENSATION AND METABOLISM;
VOMERONSASAL AND CHEMICAL
COMMUNICATION
Insights into the Function of Darcin from the Three
Dimensional Structure
Robert J Beynon, Marie M Phelan, Lu-Yun Lian, Lynn McLean,
Jane L Hurst
University of Liverpool / Institute of Integrative Biology Liverpool,
United Kingdom
Mouse urine contains millimolar concentrations of major urinary
proteins (MUP) - eight stranded beta barrel lipocalins. MUPs
have a broad range of functions in chemical communication
between individuals. One MUP, darcin (MGI classification
Mup20) is highly expressed in males only and is responsible for
inherent female attraction to males, the subsequent memory of
the volatile odour profile of that male and the rapid induction
of memory of the precise physical placement of the scent mark
containing darcin. Darcin is responsible for the slow release
of the volatile pheromone, 2-sec-butyl 4,5 dihydrothiazole. To
better understand the unique properties of darcin, we have
solved the structure of this protein by NMR. Relative to other
MUPs, darcin has a large solvent exposed area and the greatest
exposure of hydrophobic residues in the beta barrel. Binding
to three ligands – NPN, menadione and a thiazole derivative
– were characterized in this study. Menadione and thiazole
bound to both darcin and MUP11 in the hydrophobic cavity
of the beta barrel, with NMR data indicating a similar binding
site for menadione and thiazole in both darcin and MUP11.
The largest ligand (NPN) bound only to MUP11, not darcin,
suggesting darcin adopts a more compact binding cavity. Darcin
is significantly more stable than MUP11, with 92% of darcin
structure retained in the native state at 7M urea compared to
only 45% in MUP11. The high stability of darcin is consistent
with the anomalous migration on SDS-PAGE and a tendency to
undercharge in electrospray ionisation mass spectrometers. All
this biophysical and ligand binding data point to darcin adopting
a more stable and compact conformation with a smaller ligand
binding cavity than related MUPs. Acknowledgements: These
studies were supported by the Biotechnology and Biological
Science Research Council (BB/J002631/1).
HCN Channels Mediate Proton-dependent Signaling in the
Mouse Vomeronasal Organ
Annika Cichy, Tobias Ackels, Jennifer Spehr, Marc Spehr
RWTH Aachen University, Dept. Chemosensation Aachen, Germany
The mouse vomeronasal organ (VNO) plays an important role in
the detection of semiochemicals and other social cues. However,
many of the basic mechanisms that control VNO physiology
remain largely unknown. Here, we investigate proton-mediated
activity in the mouse VNO. We show that mouse urine is not
only a rich source of social chemosignals, but can also create
an acidic environment for such cues. For females, in particular,
we find an experience-dependent variation of their generally
low urinary pH. Using whole-cell patch-clamp recordings from
visually identified sensory neurons in acute tissue slices of
the mouse VNO, we show that vomeronasal sensory neurons
are activated by protons. We describe that acidic solutions
dose-dependently induce inward currents in voltage-clamp
measurements and elicit robust action potential firing in currentclamp
recordings. Surprisingly, our investigations suggest
no substantial involvement of ‘classical’ candidate protonactivated
ion channels. Instead, the pharmacological profile and
biophysical properties of the proton-induced responses indicate
a critical role of hyperpolarization-activated cyclic-nucleotidegated
(HCN) ion channels in proton-mediated signaling of
vomeronasal sensory neurons. Together, our results implicate
HCN channel-dependent vomeronasal acid-sensing in gain
control of social chemosignaling.
#P194 POSTER SESSION IV:
CHEMICAL SIGNALING AND BEHAVIOR;
ANIMAL BEHAVIOR/PSYCHOPHYSICS;
CHEMOSENSATION AND METABOLISM;
VOMERONSASAL AND CHEMICAL
COMMUNICATION
Kirrel-3 is Required for the Coalescence of Vomeronasal
Sensory Neuron Axons into Glomeruli and for Male-Male
Aggression
Jean-François Cloutier 1,2 , Alexandra Brignall 1,2 , Tyler Cutforth 3 ,
Kang Shen 4 , Janet Prince 1,2
1
Montreal Neurological Institute Montréal, QC, Canada, 2 McGill
University Montréal, QC, Canada, 3 University of California Irvine,
CA, USA, 4 Stanford University Stanford, CA, USA
POSTER PRESENTATIONS
The accessory olfactory system controls social and sexual
interactions in mice that are critical for survival. Vomeronasal
sensory neurons (VSNs) form synapses with dendrites of
second order neurons in glomeruli of the accessory olfactory
bulb (AOB). Axons of VSNs expressing the same vomeronasal
receptor (VR) coalesce into multiple glomeruli within spatially
Abstracts are printed as submitted by the author(s).
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