如果你煮咖啡从来不放糖，抑或烤薄饼从不加糖浆，那么在你的血管里可能多少流淌着一些欧洲祖先的血液。新的研究显示，与那些拥有世界其他地区血统的人相比，欧洲人的后裔对甜味更为敏感。
由美国马里兰州贝塞斯达市国立耳聋与其他交流障碍研究所的Alexey Fushan领导的研究小组，调查了144名具有不同种族背景的志愿者，让他们对浓度为0%到4%的9种糖溶液的甜度进行了排序。结果显示，志愿者的蔗糖敏感性与一种名为TAS1R3的基因——它在主要碳水化合物甜味受体的编码过程中扮演了一个主要角色——的两种变异具有强烈的关联。
通过借鉴CEPH（法国基因数据库）提供的全球1050人的脱氧核糖核酸（DNA）信息，研究小组发现，大多数欧洲人都具有这两种与甜味敏感性有关的变异。这些变异较少出现在亚洲人和中东人之中，并且在非洲人中分布得最为稀少。研究小组在即将于8月11日出版的《现代生物学》（Current Biology）杂志上报告这一研究成果。
这篇论文的共同作者、遗传学家Dennis Drayna认为，甜度敏感性的这种差异或许在人类的进化过程中具有重要意义。他强调说：“那些研究食物与进化关系的科学家就曾经指出，大多数含糖量较高的植物，例如甘蔗，都是热带植物。因此在纬度较高的北方地区，为了获得卡路里，你不得不对甜味更为敏感。”美国达拉斯市得克萨斯大学西南医学中心的分子生物学家Stephen Wooding同样认为这一遗传差异可能是适应性的结果。但他表示，精确的适应机制现在尚未搞清。（生物谷Bioon.com）
生物谷推荐原始出处：
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.
