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图片摘自：vegetarian.about.com
2016年4月11日 讯 /生物谷BIOON/ –喜好植物性饮食的个体或许天生就是这样；近日一项刊登于国际杂志Molecular Biology and Evolution上的研究报告中，来自康奈尔大学的研究人员在那些素食主义者机体中发现了一种特殊的遗传突变会随着一代又一代不断发生着进化。
从历史角度来讲，素食人群主要在印度、非洲和东亚部分地区居住，科学家们发现，这些遗传适应性可以促使素食主义者更加有效地加工omega-3和omega-6脂肪酸，并且将这些脂肪酸转化成为对早期大脑发育的有用化合物。
但本文中研究者发现，这些所谓的“素食基因”或许会增加部分人群患心脏病和结肠癌的风险，在那些绿色饮食并且机体中含有遗传变异的个体中，如果其机体中偏离了omega-3和omega-6饮食的平衡，或许就使得个体对炎症更加易感，同时也会增加这些个体患心脏疾病和结肠癌的风险。
研究人员对234名最初的素食印度人及311名美国人进行了机体中“素食”遗传突变频率的研究调查，仅有18%的美国研究对象机体中含有这种特殊的素食基因，而这种特殊的素食基因却在68%的印度人群中存在。后期研究者还将继续深入研究，他们希望可以揭示这些素食基因的发生机制及对人类机体的影响。（基因宝jiyinbao.com）
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Positive Selection on a Regulatory Insertion–Deletion Polymorphism in FADS2 Influences Apparent Endogenous Synthesis of Arachidonic Acid
Kumar S. D. Kothapalli*,1,†, , Kaixiong Ye2,†, Maithili S. Gadgil3, Susan E. Carlson4, Kimberly O. O’Brien1, Ji Yao Zhang1, Hui Gyu Park1, Kinsley Ojukwu1, James Zou1, Stephanie S. Hyon1, Kalpana S. Joshi3, Zhenglong Gu1, Alon Keinan*,2 and J.Thomas Brenna*,1
Long chain polyunsaturated fatty acids (LCPUFA) are bioactive components of membrane phospholipids and serve as substrates for signaling molecules. LCPUFA can be obtained directly from animal foods or synthesized endogenously from 18 carbon precursors via the FADS2 coded enzyme. Vegans rely almost exclusively on endogenous synthesis to generate LCPUFA and we hypothesized that an adaptive genetic polymorphism would confer advantage. The rs66698963 polymorphism, a 22-bp insertion–deletion within FADS2, is associated with basal FADS1 expression, and coordinated induction of FADS1 and FADS2 in vitro. Here, we determined rs66698963 genotype frequencies from 234 individuals of a primarily vegetarian Indian population and 311 individuals from the US. A much higher I/I genotype frequency was found in Indians (68%) than in the US (18%). Analysis using 1000 Genomes Project data confirmed our observation, revealing a global I/I genotype of 70% in South Asians, 53% in Africans, 29% in East Asians, and 17% in Europeans. Tests based on population divergence, site frequency spectrum, and long-range haplotype consistently point to positive selection encompassing rs66698963 in South Asian, African, and some East Asian populations. Basal plasma phospholipid arachidonic acid (ARA) status was 8% greater in I/I compared with D/D individuals. The biochemical pathway product–precursor difference, ARA minus linoleic acid, was 31% and 13% greater for I/I and I/D compared with D/D, respectively. This study is consistent with previous in vitro data suggesting that the insertion allele enhances n-6 LCPUFA synthesis and may confer an adaptive advantage in South Asians because of the traditional plant-based diet practice.