Abstracts - Association for Chemoreception Sciences

self renew, as well as produce post-mitotic cells which either
differentiate into lingual epithelial cells (K13+), or enter buds
and differentiate into type I, II and III taste cells (K8+). We
previously showed that Wnt/b-catenin signaling is active in
cells in and around taste buds of adult mice (Gaillard & Barlow,
2011), suggesting that this pathway may regulate several aspects
of taste cell renewal. To test this idea, we used inducible Cre-lox
technology to drive b-catenin gain of function (GOF) in K14+
basal keratinocytes throughout the tongue epithelium, including
the fungiform and circumvallate papillae (CVP). In the CVP
trenches, K13+ cells located between taste buds vanished in the
GOF, and instead all cells within the CVP epithelium expressed
K8. Using immunomarkers for each of the 3 taste cell types,
we found that this expanded taste CVP epithelium comprised
primarily NTPdase2+ type I cells, with little or no change in
the numbers of type II and III cells. Likewise, in the anterior
tongue, b-catenin GOF induced multiple K8+ cell clusters within
fungiform papillae, as well as numerous ectopic K8+ cell clusters
in non-taste epithelium; all of these cell clusters were exclusively
NTPdase2+, and were devoid of expression of markers for type
II and III taste cells. Our data indicate that excess Wnt/b-catenin
signaling drives epithelial progenitors to produce daughter cells
committed to a taste fate (K8+) at the expense of a non-taste
fate (K13+), and moreover constrains these newly generated
taste cells to a type I cell fate. We are now examining what
cellular mechanisms are triggered by excess b-catenin, and how
these changes in cell renewal result in the GOF phenotype.
Acknowledgements: Supported by an American Heart
Association fellowship to DG, NIH/NIDCD DC008373 and
DC012383 to LAB, and DC004657 to D. Restrepo.
#30 PLATFORM PRESENTATIONS —
POLAK YOUNG INVESTIGATOR AWARD WINNERS
Target-defined olfactory bulb output streams isolated using
retrograde infection with recombinant viral vectors
Markus Rothermel, Christine Zabawa, Daniela Brunert,
Marta Diaz-Quesada , Matt Wachowiak
Brain Institute and Department of Physiology Salt Lake City, UT, USA
Recombinant viral vectors are an attractive tool for cell-type
specific transgene expression, especially when Cre-dependent
vectors are combined with Cre-expressing mouse lines.
However, cell-type specific promoters do not always yield
sufficient specificity for isolating functionally distinct neuronal
populations. In the olfactory system mitral and tufted cells (MT)
of the olfactory bulb (OB) constitute a heterogenous population
with distinct dendritic organization, response properties and
projections to olfactory cortex. Here, we demonstrate that by
combining viral tools with retrograde infection via their axonal
processes, MT cells can be defined by projection target. We
injected Cre-dependent AAV vectors into various regions of
olfactory cortex in Cdhr1-cre mice. Virus injection into anterior
piriform cortex (PC) led to robust and widespread transgene
expression in MT cells throughout the OB. To establish that
expression patterns were due to retrograde infection we targeted
additional olfactory cortical areas: injection into posterior PC
or posterior cortical amygdala led to expression exclusively in
mitral cells with lateral dendrites in the deep external plexiform
layer, while injection into medial amygdala led to expression
solely in mitral cells of the accessory olfactory bulb. Retrograde
infection was effective using multiple transgenes including
GCaMP and ChR2, allowing for optical imaging, optical control
or optically-assisted electrophysiology of distinct OB output
streams defined by their projection target. Retrograde infection
was also effective for projection neurons in other brain regions.
These results establish a valuable, easily-used tool for achieving
combinatorial specificity in transgene expression to monitor
and manipulate precisely-defined neuron populations in vivo.
Acknowledgements: Supported by DFG and NIDCD
#31 PLATFORM PRESENTATIONS —
POLAK YOUNG INVESTIGATOR AWARD WINNERS
Major contribution of Gao-dependent vomeronasal
chemoreception to sexual and reproductive behavior in
female mice
Livio Oboti 1 , Trese Leinders-Zufall 1 , Eric Jacobi 1,3 , Lutz Birnbaumer 2 ,
Frank Zufall 1 , Pablo Chamero 1
1
Department of Physiology, University of Saarland School of
Medicine Homburg, Germany, 2 Laboratory of Neurobiology, Division
of Intramural Research, National Institutes of Health Research
Triangle Park, NC, USA, 3 Deutsches Zentrum für Neurodegenerative
Erkrankungen (DZNE) Heidelberg, Germany
Optimal reproductive fitness is essential for the biological
success and survival of species. The vomeronasal organ (VNO)
is strongly implicated in the display of sexual and reproductive
behaviors in female mice, yet the role that apical and basal
vomeronasal neuron populations play in controlling these
gender-specific behaviors remain largely unclear. To dissect
neural pathways underlying these functions, we genetically
inactivated the basal VNO layer using conditional, cell-specific
ablation of the G protein Gao. Female mice mutant for Gao
show severe alterations in mate recognition, mating, and
reproduction. Male pheromonal cues fail to accelerate puberty
onset and estrous synchronization in these mice. Gao mutant
females exhibit a striking reduction in sexual receptivity or
lordosis behavior to males, but gender discrimination seems
to be intact. These mice also show a loss in scent ownership
recognition that requires a learned association with a nonvolatile
ownership signal contained in the high molecular weight fraction
of urine, and they show high pregnancy failure rates in the
Bruce effect assay. These results indicate that sensory neurons
of the Gao-expressing vomeronasal subsystem, together with
the receptors they express and the molecular cues they detect,
control a diverse range of fundamental mating and reproductive
behaviors in female mice. Acknowledgements: This work was
supported by grants from the Deutsche Forschungsgemeinschaft
to P.C. (CH 920/2-1), F.Z. (SFB 894) and T.L-Z. (SFB 894),
the Intramural Research Program of the NIH to L.B. (Project
Z01 ES-101643), and the Volkswagen Foundation (to T.L.-Z.).
E.J. was supported by the DFG-funded International Graduate
Program GK1326. T.L.-Z. is a Lichtenberg Professor of the
Volkswagen Foundation.
ORAL ABSTRACTS
Abstracts are printed as submitted by the author(s).
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