约300万年前,人类基因进化以便能产生较多的Omega-3和omega-6脂肪酸。这种基因进化可能在现代人独特的脑容量的发展中发挥至关重要作用。在如今生活环境下,这种基因进化的贡献可能更是诱发疾病如心血管疾病的风险因素。
人体神经系统和大脑中含有大量的多不饱和脂肪酸,这些对大脑的发育和功能都很重要。含含量的ω-3和Omega-6脂肪酸存在于少数食物品种如鱼类中。我们的身体利用某些植物油酸也可以生成这些重要的脂肪酸。
目前,乌普萨拉大学人类遗传学的科学研究人员在The American Journal of Human Genetics杂志上发表了一项新的研究论文,该研究关注于从植物油中合成Omega-3和ω-6脂肪酸需要两个关键酶的基因。研究人员发现人类有一个能导致Omega-3和ω-6脂肪酸产量增加的独特的遗传变异。高生成量Omega-3和Omega-6脂肪酸的基因进化只在人类身上发现,而我们灵长类亲戚黑猩猩、大猩猩和猕猴不存在。尼安德特人或丹尼索瓦人也没有这种遗传变异。
从植物油中生成更有效的Omega-3和Omega-6的遗传变化在非洲体现尤为明显,这一遗传变化对人们在有限的膳食脂肪酸生存环境中生存是一个重要因素。
生物信息学、免疫学、遗传学和病理学系的Adam Ameur说:在人类的早期发展阶段,当一般能源缺失时,这种遗传变化会让我们要满足了我们独特的脑容量所需的多不饱和脂肪酸伟大的需要成为可能。在如今营养过剩的生活状况下,这遗传适应的贡献往往可能是诱发疾病如心血管疾病的风险因素。
遗传学和病理学系医学分子遗传学教授Ulf Gyllensten说:这项研究首次证实人体脂肪代谢的遗传变异。这一基因进化对促进人类发展,增强人类的早期生存很重要,但在粮食过剩的今天,这一基因进化或许成为了疾病的危险因素。(生物谷:Bioon.com)
doi:10.1016/j.ajhg.2012.03.014
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Genetic Adaptation of Fatty-Acid Metabolism: A Human-Specific Haplotype Increasing the Biosynthesis of Long-Chain Omega-3 and Omega-6 Fatty Acids
Adam Ameur1, Stefan Enroth1, ?sa Johansson1, Ghazal Zaboli1, Wilmar Igl1, Anna C.V. Johansson1, Manuel A. Rivas2, Mark J. Daly2, Gerd Schmitz3, Andrew A. Hicks6, Thomas Meitinger9, Lars Feuk1, Cornelia van Duijn4, Ben Oostra5, Peter P. Pramstaller6, 7, 8, Igor Rudan10, 11, Alan F. Wright12, James F. Wilson11, Harry Campbell11 and Ulf Gyllensten1,
Omega-3 and omega-6 long-chain polyunsaturated fatty acids (LC-PUFAs) are essential for the development and function of the human brain. They can be obtained directly from food, e.g., fish, or synthesized from precursor molecules found in vegetable oils. To determine the importance of genetic variability to fatty-acid biosynthesis, we studied FADS1 and FADS2, which encode rate-limiting enzymes for fatty-acid conversion. We performed genome-wide genotyping (n = 5,652 individuals) and targeted resequencing (n = 960 individuals) of the FADS region in five European population cohorts. We also analyzed available genomic data from human populations, archaic hominins, and more distant primates. Our results show that present-day humans have two common FADS haplotypesdefined by 28 closely linked SNPs across 38.9 kbthat differ dramatically in their ability to generate LC-PUFAs. No independent effects on FADS activity were seen for rare SNPs detected by targeted resequencing. The more efficient, evolutionarily derived haplotype appeared after the lineage split leading to modern humans and Neanderthals and shows evidence of positive selection. This human-specific haplotype increases the efficiency of synthesizing essential long-chain fatty acids from precursors and thereby might have provided an advantage in environments with limited access to dietary LC-PUFAs. In the modern world, this haplotype has been associated with lifestyle-related diseases, such as coronary artery disease.