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Unformatted text preview: Supertasting and PROP Bitterness Depends on More Than the TAS2R38 Gene John E. Hayes 1,2 , Linda M. Bartoshuk 3 , Judith R. Kidd 4 and Valerie B. Duffy 5 1 Department of Nutritional Sciences, College of Agriculture and Natural Resources, University of Connecticut, 3624 Horsebarn Road Ext, Storrs, CT 06269-2101, USA, 3 Department of Community Dentistry and Behavioral Science, College of Dentistry, University of Florida, PO Box 103628, Gainesville, FL 32610-3628, USA, 4 Department of Genetics, School of Medicine, Yale University, PO Box 208005, New Haven, CT 06520-8005, USA, and 5 Department of Allied Health Sciences, College of Agriculture and Natural Resources, University of Connecticut, 358 Mansfield Road, Unit 2101, Storrs, CT 06269-2101, USA 2 Present address: Center for Alcohol and Addictions Studies, Brown University, Box G-S121-4, Providence, RI 02912, USA Correspondence to be sent to: Valerie B. Duffy, Department of Allied Health Sciences, College of Agriculture and Natural Resources, University of Connecticut, 358 Mansfield Road, Unit 2101, Storrs, CT 06269-2101, USA. e-mail: email@example.com Abstract Polymorphisms in the TAS2R38 gene provide insight to phenotypes long associated 6- n-propylthiouracil (PROP) and phenylthio- carbamide bitterness. We tested relationships between TAS2R38 genotype, taste phenotype, and fungiform papillae (FP) num- ber in 139 females and 59 males (age range 2160 years), primarily of European ancestry. DNA was analyzed for 3 polymorphic sites, identifying common (alaninevalineisoleucine [AVI/AVI], heterozygotes, prolinealaninevaline [PAV/PAV]) and rare (prolinevalineisoleucine, alaninealaninevaline, AAI) forms. Individuals with PROP threshold > 0.15 mM were almost exclu- sively AVI/AVI; those with threshold < 0.1 mM could have any genotype. PAV/PAVs were more difficult to identify with PROP taste measures, although perceived bitterness of moderate PROP concentrations (0.32, 1 mM) had better correspondence with ge- notype than did threshold. For AVI/AVIs, increases in bitterness from 1 to 3.2 mM PROP nearly paralleled those of TAS2R38 heterozygotes and PAV/PAVs. Some bitterness gains were related to FP number sampled from a standard area on the tongue tip, yet the PROP bitternessFP relationship differed across genotype. Among homozygotes, FP was a significant determinant of PROP bitterness; heterozygotes showed a at relationship. Those tasting concentrated PROP as more bitter also tasted concen- trated sucrose, citric acid, sodium chloride, and quinine as more intense, even after statistically controlling for TAS2R38 genotype, FP, and intensity of tones (nonoral standard). To summarize, although PROP threshold generally exhibited single-gene complete dominance, PROP bitterness may involve additional bitter receptors as evidenced by misclassification of some nontaster homo- zygotes and the bitterness functions for concentrated PROP. Variability in receptor expression may explain attenuated bitternesszygotes and the bitterness functions for concentrated PROP....
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This note was uploaded on 06/13/2011 for the course PSYCH 115 taught by Professor Shaine during the Spring '07 term at UCLA.
- Spring '07