| Title: | Relaxation of selective constraint and loss of function in the evolution of human bitter taste receptor genes |
| Author(s): | Wang X; Thomas SD; Zhang J; |
| Address: | "Department of Ecology and Evolutionary Biology, University of Michigan, 830 North University Avenue, Ann Arbor, MI 48109, USA" |
| ISSN/ISBN: | 0964-6906 (Print) 0964-6906 (Linking) |
| Abstract: | "Bitter taste perception prevents mammals from ingesting poisonous substances because many toxins taste bitter and cause aversion. We hypothesize that human bitter taste receptor (TAS2R) genes might be relaxed from selective constraints because of the change in diet, use of fire and reliance on other means of toxin avoidance that emerged in human evolution. Here, we examine the intra-specific variations of all 25 genes of the human TAS2R repertoire. Our data show hallmarks of neutral evolution, including similar rates of synonymous (d(S)) and non-synonymous (d(N)) nucleotide changes among rare polymorphisms, common polymorphisms and substitutions; no variation in d(N)/d(S) among functional domains; segregation of pseudogene alleles within species and fixation of loss-of-function mutations. These results, together with previous findings of large numbers of loss-of-function mutations in olfactory, pheromonal and visual sensory genes in humans, suggest surprisingly reduced sensory capabilities of humans in comparison with many other mammals" |
| Keywords: | "Africa Black or African American/genetics Animals Asian People/genetics *Evolution, Molecular Genetic Variation Humans Indians, South American/genetics Mammals/genetics Mutation Native Hawaiian or Other Pacific Islander/genetics Pan troglodytes/genetics P;" |
| Notes: | "MedlineWang, Xiaoxia Thomas, Stephanie D Zhang, Jianzhi eng GM67030/GM/NIGMS NIH HHS/ Comparative Study Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, P.H.S. England 2004/09/16 Hum Mol Genet. 2004 Nov 1; 13(21):2671-8. doi: 10.1093/hmg/ddh289. Epub 2004 Sep 14" |
