Abstracts - Association for Chemoreception Sciences

#P240 POSTER SESSION V:
HUMAN TASTE PSYCHOPHYSICS;
OLFACTION RECEPTORS; TASTE DEVELOPMENT
The role of gene expression in the human TAS2R38
genotype-phenotype relationship
Sarah V. Lipchock 1 , Andrew I. Spielman 2 , Julie A. Mennella 1 ,
Danielle R. Reed 1
1
Monell Chemical Senses Center Philadelphia, PA, USA, 2 College of
Dentistry, New York University New York, NY, USA
Bitter taste is important for sensing and avoiding toxins, but the
aversion to bitter can lead to low consumption of vegetables,
an important source of phytochemicals. Single-nucleotide
polymorphisms in the genes that code for the 25 human bitter
receptors (TAS2Rs) result in different individual responses to
taste stimuli. One example of this phenomenon is the TAS2R38
gene, which encodes a receptor that recognizes compounds
including 6-n-propylthiouracil (PROP) and goitrin, found
in broccoli. Cell-based assays and psychophysical threshold
measurements confirm that receptor with the amino acid
sequence PAV responds to PROP, while the AVI form does not.
Heterozygous (PAV/AVI) individuals display a broad range of
abilities to taste PROP. To examine the role of allele-specific
gene expression in the TAS2R38 genotype-phenotype relationship
we recruited healthy, non-smoking adults with the PAV/AVI
diplotype (N=18). Psychophysical ratings for several bitter
compounds and vegetable juices were related to levels of TAS2R
gene expression from human fungiform taste papillae. Increased
levels of the PAV form of TAS2R38 were positively correlated
with the subject’s intensity ratings for PROP and broccoli juice.
Expression of TAS2R43 was associated with ratings for caffeine,
urea, denatonium benzoate and quinine. This relationship
resulted from copy number variation of TAS2R43 and suggests
that TAS2R43 acts as a proxy for bitterness sensitivity from the
cluster of receptors on chromosome 12. Our data provide a link
between genotype and phenotype in the taste system. Our work
lays a foundation for future studies about regulatory mechanisms
and implications of taste receptor expression as it relates to diet
and vegetable consumption in humans. Acknowledgements:
Supported by F32DC011975 (SVL), P30DC011735 (DRR) and
R01DC011287 (JAM).
#P241 POSTER SESSION V:
HUMAN TASTE PSYCHOPHYSICS;
OLFACTION RECEPTORS; TASTE DEVELOPMENT
Evidence that cooling affects the sweetness of sugars via 2
separate mechanisms.
Danielle J. Nachtigal 1 , Barry G. Green 1,2
1
The John B. Pierce Laboratory New Haven, CT, USA, 2 Department of
Surgery, Yale University School of Medicine New Haven, CT, USA
Previous experiments in our laboratory demonstrated that
temperature can affect the sweetness of sucrose, glucose, and
fructose solutions by modulating taste adaptation: Cooling from
37°C to 21°C significantly increased the rate and amount of selfadaptation
when the tongue tip was dipped into the solutions for
several seconds. However, cooling to 21°C did not reduce initial
sweet taste intensity, and thus did not directly affect sensitivity
to the sugars. In the present study we investigated whether
cooling to colder temperatures would further accelerate sweet
taste adaptation and/or begin to reduce sweet taste sensitivity.
Subjects rated the sweetness of 0.42 M sucrose solutions at
temperatures of 41°, 37°, 30°, 21°, 10° or 5°C after dipping
the tongue tip for 0, 3, or 10 sec into either 0.42 M sucrose or
pure dH 2
O of the same temperature. Sweetness ratings were
made prior to retracting the tongue back into the mouth. There
were two main findings: (1) sweet taste adaptation increased
significantly at 21°C (replicating our previous results), and
(2) pre-exposure to pure dH 2
O at 5° or 10°C significantly
reduced sweet taste intensity independent of taste adaptation.
These findings indicate that cooling interferes with the
perception of sucrose sweetness in two different ways: mild
cooling increases the rate of adaptation whereas more extreme
cooling reduces the initial sensitivity to sucrose. Experiments
are planned that will test the hypothesis that these two effects
occur at different stages of the transduction cascade, with the
former affecting the binding of sucrose to the transmembrane
region of the T1R2-T1R3 receptor, and the latter modulating a
temperature-sensitive intracellular mechanism that is common to
G-protein coupled receptors (e.g., TRPM5). Acknowledgements:
NIH grant RO1 DC005002
#P242 POSTER SESSION V:
HUMAN TASTE PSYCHOPHYSICS;
OLFACTION RECEPTORS; TASTE DEVELOPMENT
The Chemosensory Component in the 2012 National Health
and Nutrition Examination Survey (NHANES): Test-Retest
Analysis and Comparison with Laboratory-Based Measures
Shristi Rawal 1 , Howard J Hoffman 2 , Kathy Bainbridge 2 ,
Valerie B Duffy 1
1
University of Connecticut/Allied Health Sciences Storrs, CT, USA,
2
National Institute on Deafness and Other Communication Disorders/
Division of Scientific Programs Bethesda, MD, USA
The NHANES now includes a standardized chemosensory
protocol with brief assessments of taste intensity and odor
identification conducted in a mobile exam center. After
orientation to the general Labeled Magnitude Scale and scaling
intensity of LED-generated lights, participants report intensities
of 1 M NaCl and 1 mM quinine hydrochloride applied to the
tongue tip and these plus 0.32 M NaCl with the whole mouth.
Olfactory dysfunction is assessed with two 4-item, scratchand-sniff
tests (Pocket Tests (PT), Sensonics, Inc) with food
(strawberry, chocolate, onion, grape) and common (leather,
soap, smoke, natural gas) odors. Here we examined test-retest
reliabilities of the chemosensory protocol, compared the PT
with an olfactometer identification task, and added scaling
to all odor tests. Fifty adults (mean age=27, range 18-62 yrs),
primarily Caucasian and Asian, college-educated and reportedly
healthy, were tested in a laboratory twice within two weeks.
POSTER PRESENTATIONS
Abstracts are printed as submitted by the author(s).
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