BGI-Shenzhen, Shenzhen 518083, China; School of Bioscience and Biotechnology, South China University of Technology, Guangzhou 510641, China.
Department of Integrative Biology, 3060 Valley Life Sciences Building, University of California, Berkeley, CA 94720, USA; Centre for GeoGenetics, Natural History Museum, University of Copenhagen, Øster Voldgade 5-7, 1350 Copenhagen K, Denmark.
Cell. 2014 May 8;157(4):785-94. doi: 10.1016/j.cell.2014.03.054.
Polar bears are uniquely adapted to life in the High Arctic and have undergone drastic physiological changes in response to Arctic climates and a hyper-lipid diet of primarily marine mammal prey. We analyzed 89 complete genomes of polar bear and brown bear using population genomic modeling and show that the species diverged only 479-343 thousand years BP. We find that genes on the polar bear lineage have been under stronger positive selection than in brown bears; nine of the top 16 genes under strong positive selection are associated with cardiomyopathy and vascular disease, implying important reorganization of the cardiovascular system. One of the genes showing the strongest evidence of selection, APOB, encodes the primary lipoprotein component of low-density lipoprotein (LDL); functional mutations in APOB may explain how polar bears are able to cope with life-long elevated LDL levels that are associated with high risk of heart disease in humans.
北极熊是高纬度北极地区特有的物种，为适应北极气候和以海洋哺乳动物为主的高脂饮食，它们在生理上发生了巨大变化。我们利用群体基因组建模分析了 89 只北极熊和棕熊的完整基因组，结果表明，这两个物种在 47.9 万至 34.3 万年前才开始分化。我们发现，北极熊谱系中的基因受到的正选择强于棕熊；在受强烈正选择影响的前 16 个基因中，有 9 个与心肌病和血管疾病有关，这意味着心血管系统发生了重要的重组。在受到最强选择证据支持的基因中，APOB 编码 LDL 的主要脂蛋白成分；APOB 的功能突变可能解释了北极熊如何能够长期应对与人类心脏病高风险相关的高 LDL 水平。
