BACKGROUND: During periods of human expansion into new environments, recognition of bitter natural toxins through taste may have conferred an important selective advantage. The G protein-coupled receptor encoded by TAS2R16 mediates response to salicin, amygdalin, and many bitter beta-glucopyranosides. beta-glucopyranosides are ubiquitous in nature, with many having a highly toxic cyanogenic activity. RESULTS: We examined evidence for natural selection on the human receptor TAS2R16 by sequencing the entire coding region, as well as part of the 5' and 3' UTRs, in 997 individuals from 60 human populations. We detected signatures of positive selection, indicated by an excess of evolutionarily derived alleles at the nonsynonymous site K172N and two linked sites and significant values of Fay and Wu's H statistics in 19 populations. The estimated age range for the common ancestor of the derived N172 variant is 78,700-791,000 years, placing it in the Middle Pleistocene and before the expansion of early humans out of Africa. Using calcium imaging in cells expressing different receptor variants, we showed that N172 is associated with an increased sensitivity to salicin, arbutin, and five different cyanogenic glycosides. CONCLUSION: We have detected a clear signal of positive selection at the bitter-taste receptor gene TAS2R16. We speculate that the increased sensitivity that is shown toward harmful cyanogenic glycosides and conferred by the N172 allele may have driven the signal of selection at an early stage of human evolution.
BACKGROUND: During periods of human expansion into new environments, recognition of bitter natural toxins through taste may have conferred an important selective advantage. The G protein-coupled receptor encoded by TAS2R16 mediates response to salicin, amygdalin, and many bitter beta-glucopyranosides. beta-glucopyranosides are ubiquitous in nature, with many having a highly toxic cyanogenic activity. RESULTS: We examined evidence for natural selection on the human receptor TAS2R16 by sequencing the entire coding region, as well as part of the 5' and 3' UTRs, in 997 individuals from 60 human populations. We detected signatures of positive selection, indicated by an excess of evolutionarily derived alleles at the nonsynonymous site K172N and two linked sites and significant values of Fay and Wu's H statistics in 19 populations. The estimated age range for the common ancestor of the derived N172 variant is 78,700-791,000 years, placing it in the Middle Pleistocene and before the expansion of early humans out of Africa. Using calcium imaging in cells expressing different receptor variants, we showed that N172 is associated with an increased sensitivity to salicin, arbutin, and five different cyanogenic glycosides. CONCLUSION: We have detected a clear signal of positive selection at the bitter-taste receptor gene TAS2R16. We speculate that the increased sensitivity that is shown toward harmful cyanogenic glycosides and conferred by the N172 allele may have driven the signal of selection at an early stage of human evolution.
Authors: John E Hayes; Margaret R Wallace; Valerie S Knopik; Deborah M Herbstman; Linda M Bartoshuk; Valerie B Duffy Journal: Chem Senses Date: 2010-12-16 Impact factor: 3.160
Authors: Anthony L Hinrichs; Jen C Wang; Bernd Bufe; Jennifer M Kwon; John Budde; Rebecca Allen; Sarah Bertelsen; Whitney Evans; Danielle Dick; John Rice; Tatiana Foroud; John Nurnberger; Jay A Tischfield; Samuel Kuperman; Raymond Crowe; Victor Hesselbrock; Marc Schuckit; Laura Almasy; Bernice Porjesz; Howard J Edenberg; Henri Begleiter; Wolfgang Meyerhof; Laura J Bierut; Alison M Goate Journal: Am J Hum Genet Date: 2005-11-21 Impact factor: 11.025
Authors: Michael C Campbell; Alessia Ranciaro; Daniel Zinshteyn; Renata Rawlings-Goss; Jibril Hirbo; Simon Thompson; Dawit Woldemeskel; Alain Froment; Joseph B Rucker; Sabah A Omar; Jean-Marie Bodo; Thomas Nyambo; Gurja Belay; Dennis Drayna; Paul A S Breslin; Sarah A Tishkoff Journal: Mol Biol Evol Date: 2013-10-30 Impact factor: 16.240