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salicin, water, and for each of these combined with 0.5M sucrose.
Each of 12 hamsters received each stimulus once in a Latin square
design. Data were analyzed by ANOVA and post-hoc tests (p =
0.05). All 5 bitter stimuli presented alone were rejected at the
concentrations used (preference ratios 0.15 to 0.25). Sucrose alone
was preferred (preference ratio 0.7). Addition of sucrose improved
the palatability of quinine, chlorhexidine and salicin (preference
ratio 0.6 to 0.75) but had no effect on the palatability of
cycloheximide or caffeine. These results suggest that
cycloheximide and caffeine have different mechanisms of detection
or physiological responses than the other bitter stimuli. It is
noteworthy that cycloheximide and caffeine can have potent non-
sensory effects that could explain their resistance to sucrose
amelioration. Consistent with this interpretation, consumption of
cycloheximide, a known inhibitor of protein synthesis and an
unconditioned stimulus for aversion learning, was reduced in the
second 24-hr period as compared to the first; and learned aversions
to caffeine, a stimulant, are known for failing to generalize to the
bitter prototype quinine in hamsters. Acknowledgements:
Supported by UConn SDMAlumni Research Fellowship and
NIH grant DC004099.
#P160
POSTER SESSION IV:
CHEMICAL SIGNALING & BEHAVIOR;
PSYCHOPHYSICS; CHEMOSENSATION & DISEASE;
OLFACTION PERIPHERY; TASTE PERIPHERY
Contribution of Taste to Carbohydrate-Induced Obesity in
C57BL/6 Mice
John I. Glendinning
1
, Jennifer Gilman
1
, Haley Zamer
1
,
Robert F. Margolskee
2
, Anthony Sclafani
3
1
Barnard College, Department of Biology New York, NY, USA,
2
Monell Chemical Senses Center Philadelphia, PA, USA,
3
Brooklyn College, Department of Psychology Brooklyn, NY, USA
We asked whether taste contributes to carbohydrate-induced
obesity in C57BL/6 (B6) mice. Taste was manipulated by studying
B6 mice that lacked T1r3 or Trpm5. T1r3 is part of the T1r2+T1r3
sugar receptor, and Trpm5 mediates signaling for several G protein-
coupled receptors in taste cells. Previously, we established that the
taste of Polycose (a glucose polymer) stimulates intake in B6 and
T1r3 knock-out (KO) mice, but not in Trpm5 KO mice; whereas
the taste of sucrose stimulates intake in B6 mice, but not in T1r3
KO or Trpm5 KO mice. In Experiment 1, we maintained the B6,
T1r3 KO, and the Trpm5 KO mice on one of 3 diets for 38 days:
lab chow plus water (control diet), a 34% Polycose solution
(Polycose diet), or a 34% sucrose solution (sucrose diet). The B6
and T1r3 KO mice overconsumed the Polycose diet, exhibited high
feed efficiency (i.e., weight gained/kcal ingested) and became
obese. Although the B6 and T1r3 KO mice overconsumed the
sucrose diet, only the B6 mice exhibited a high feed efficiency and
became obese. In contrast, the Trpm5 KO mice consumed relatively
small quantities of both carbohydrate diets, and gained limited (but
significant) amounts of weight. In Experiment 2, we tested the
hypothesis that the T1r3 KO mice failed to become obese on the
sucrose diet because it lacked a highly palatable taste. We predicted
that adding a low (i.e., 1%) but highly palatable concentration of
soybean oil to the 34% sucrose solution would induce obesity in
T1r3 KO mice. The T1r3 KO mice became obese on the
oil+sucrose diet without ingesting extra calories. These findings
indicate that nutritive solutions must be highly palatable to cause
obesity in mice, and that palatability produces this effect in part by
enhancing feed efficiency. Acknowledgements: This research was
supported by grants from the NIH (DK-31135, DC03055 and
DC03155) and the Amgen Foundation.
#P161
POSTER SESSION IV:
CHEMICAL SIGNALING & BEHAVIOR;
PSYCHOPHYSICS; CHEMOSENSATION & DISEASE;
OLFACTION PERIPHERY; TASTE PERIPHERY
Proteomic analysis of ciliary membrane proteins
Judith L Van Houten
1
, Bryan A Ballif
1
, Anbazhagan Rajendran
2
,
Megan Valentine
1
1
University of Vermont, Biology Burlington, VT, USA,
2
Harvard
Medical School and Children’s Hospital Boston, MA, USA
To study ciliary membrane proteins (i.e. ion channels, receptors,
Ca
2+
pumps, and signal transduction components such as cyclases)
involved in the modulation of ciliary motility and sensory
transduction, we compared by LC-MS/MS the
Paramecium
tetraurelia
proteins that could be found in isolated cilia, the
purified ciliary membrane and the ciliary membrane in the
detergent phase after Triton X-114 phase separation. Proteins that
were identified by at least two unique peptides from each of these
preparations were filtered to false discovery rates of less than 0.7%.
Identified proteins were then ranked by spectral counts and the top
300 most abundant proteins were used for inter-preparation
comparisons. After Triton X-114 phase separation, we found that
64% of the proteins in the detergent phase were transmembrane or
membrane associated compared to 26% in the ciliary membrane
preparation. The voltage-gated Ca
2+
channel, small conductance
Ca
2+
dependent K
+
channel, adenylyl cyclases, plasma membrane
Ca
2+
ATPases and Na
+
/K
+
ATPases involved in the ciliary ion
homeostasis, Ca
2+
dependent protein kinases, and Rab GTPases
involved in the signal transduction were identified. Many of the
identified protein kinases and Rab GTPases have a putative
myristylation or prenylation site, respectively. To validate our
results, we confirmed using immunostaining and Western blots that
these channels and other signaling proteins are localized in the
cilia. The Triton X-114 phase separation proved to be a useful
method for separation of enrichment of integral ciliary membrane
proteins for analysis. Acknowledgements: Deconvolution
microscopy was completed with the help of NIH grants GM59988
and P20 RR016435-06. Mass spectrometry was carried out in the
VGN Proteomics Facility (P20 RR16462).
#P162
POSTER SESSION IV:
CHEMICAL SIGNALING & BEHAVIOR;
PSYCHOPHYSICS; CHEMOSENSATION & DISEASE;
OLFACTION PERIPHERY; TASTE PERIPHERY
Direct measurement of electrical signals in a sensory
primary cilium
Steven J. Kleene, Nancy K. Kleene
University of Cincinnati / Cancer and Cell Biology
Cincinnati, OH, USA
Most cells in the body possess a single primary cilium. These cilia
are key transducers of sensory stimuli, and defects in cilia have
been linked to several diseases. Evidence suggests that some
transduction of sensory stimuli by the primary cilium depends on
ion-conducting channels. However, the tiny size of the cilium has
been a critical barrier to understanding its electrical properties.
We report a novel method that allows sensitive, repeatable
electrical recordings from primary cilia. The cilia of cultured renal
epithelial cells were selected for study. Defects in renal cilia are
implicated in cystic kidney diseases including autosomal dominant
polycystic kidney disease (ADPKD). Adherent IMCD-3 cells were
grown on small, spherical beads that could be easily moved within
the recording chamber. In this configuration, an entire cilium could
Abstracts | 81
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