如果你煮咖啡從來不放糖,，抑或烤薄餅從不加糖漿，那么在你的血管里可能多少流淌著一些歐洲祖先的血液,。新的研究顯示,，與那些擁有世界其他地區(qū)血統(tǒng)的人相比，歐洲人的后裔對甜味更為敏感,。
由美國馬里蘭州貝塞斯達市國立耳聾與其他交流障礙研究所的Alexey Fushan領(lǐng)導(dǎo)的研究小組,，調(diào)查了144名具有不同種族背景的志愿者,，讓他們對濃度為0%到4%的9種糖溶液的甜度進行了排序,。結(jié)果顯示，志愿者的蔗糖敏感性與一種名為TAS1R3的基因——它在主要碳水化合物甜味受體的編碼過程中扮演了一個主要角色——的兩種變異具有強烈的關(guān)聯(lián),。
通過借鑒CEPH（法國基因數(shù)據(jù)庫）提供的全球1050人的脫氧核糖核酸（DNA）信息,，研究小組發(fā)現(xiàn)，大多數(shù)歐洲人都具有這兩種與甜味敏感性有關(guān)的變異,。這些變異較少出現(xiàn)在亞洲人和中東人之中,，并且在非洲人中分布得最為稀少。研究小組在即將于8月11日出版的《現(xiàn)代生物學(xué)》（Current Biology）雜志上報告這一研究成果,。
這篇論文的共同作者,、遺傳學(xué)家Dennis Drayna認為，甜度敏感性的這種差異或許在人類的進化過程中具有重要意義,。他強調(diào)說：“那些研究食物與進化關(guān)系的科學(xué)家就曾經(jīng)指出,，大多數(shù)含糖量較高的植物，例如甘蔗,，都是熱帶植物,。因此在緯度較高的北方地區(qū)，為了獲得卡路里,，你不得不對甜味更為敏感,。”美國達拉斯市得克薩斯大學(xué)西南醫(yī)學(xué)中心的分子生物學(xué)家Stephen Wooding同樣認為這一遺傳差異可能是適應(yīng)性的結(jié)果,。但他表示，精確的適應(yīng)機制現(xiàn)在尚未搞清,。（生物谷Bioon.com）
生物谷推薦原始出處：
Current Biology, 25 June 2009 doi:10.1016/j.cub.2009.06.015
Allelic Polymorphism within the TAS1R3 Promoter Is Associated with Human Taste Sensitivity to Sucrose
Alexey A. Fushan1,Christopher T. Simons2,Jay P. Slack2,Ani Manichaikul3andDennis Drayna1,,
1 National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20850, USA
2 Givaudan Flavors Corporation, Cincinnati, OH 45216, USA
3 University of Virginia, Charlottesville, VA 22904, USA
Human sweet taste perception is mediated by the heterodimeric G protein-coupled receptor encoded by the TAS1R2 and TAS1R3 genes [1,2,3,4,5,6,7]. Variation in these genes has been characterized [8], but the functional consequences of such variation for sweet perception are unknown. We found that two C/T single-nucleotide polymorphisms (SNPs) located atpositions 1572 (rs307355) and 1266 (rs35744813) upstream of the TAS1R3 coding sequence strongly correlate with human taste sensitivity to sucrose and explain 16% of population variability in perception. By using a luciferase reporter assay, we demonstrated that the T allele of each SNP results in reduced promoter activity in comparison to the C alleles, consistent with the phenotype observed in humans carrying T alleles. We also found that the distal region of the TAS1R3 promoter harbors a composite cis-acting element that has a strong silencing effect on promoter activity. We conclude that the rs307355 and rs35744813 SNPs affect gene transcription by altering the function of this regulatory element. A worldwide population survey reveals that the T alleles of rs307355 and rs35744813 occur at lowest frequencies in European populations. We propose that inherited differences in TAS1R3 transcription account for a substantial fraction of worldwide differences in human sweet taste perception.
