牦牛瘤胃微生物组的变异与牦牛高原适应

The yaks are the largest mammals only living in Qinghai-Tibet Plateau. The yaks themselves do not produce fiber-degrading enzymes, but they harbors microorganisms (including bacteria, fungi, and protozoa) that can. The yaks provide the microorganisms with a suitable habitat for growth, and the microbes supply protein, vitamins, and short-chain organic acids for the yaks. However, to date, the relationship between genome variation of yak rumen microbiome and the adaptation of the yak to high-altitude remains poorly elucidated, especially that associated with energy metabolism. For this reason, across key scientific issue 'genomic variation of yak rumen microbiome and the adaption of yak to extreme environment', this project will be performed on the basis of our discovered variation pattern of gut microbial diversity amongst yak population from three different altitudes in Qinghai-Tibet Plateau. Firstly, we will obtain yak rumen microbial metagenomic data from different altitudes, and also collect known cow rumen microbiome data. Secondly, via tools of comparative metagenomics and population genomics, we will large-scale dig yak-specific rumen microbial components and function genes (including metabolic pathways) associated with the adaptation to high-altitude. Finally, aross energy metabolism, we will deeply reveal the patterns of both adaptive evolution and gene-gene interaction of yak rumen microbiome and further perform comparative analysis with those of low-altitude cow rumen microbiome. Collectively, across the yak rumen microbiome, we expect that this project will provide much more comprehensive insights into understanding genomic mechanism of yak adaption to high altitude.

牦牛是青藏高原特有的大型哺乳动物，其自身不能产生纤维素降解酶，必须依赖瘤胃微生物协助消化纤维类食物，进而获得自身所需能量物质。然而，牦牛瘤胃微生物组的变异与牦牛高原适应性的关系知之甚少，尤其在能量代谢方面。为此，本项目将在前期已揭示的三个不同海拔下牦牛群体间肠道微生物多样性演变规律的基础上，紧紧围绕"牦牛瘤胃微生物组的变异及牦牛适应极端环境的分子机制"这一重大科学问题，通过获取不同海拔下牦牛群体瘤胃微生物宏基因组数据，结合已知的黄牛瘤胃微生物宏基因组数据，运用比较宏基因组学和群体基因组学手段，规模化发掘牦牛物种特异的、与高原适应相关的瘤胃微生物类群、功能基因及代谢通路，着重从能量代谢角度出发，来探究牦牛瘤胃微生物组的演化规律及基因互作模式，并与近缘种黄牛进行比较。在扎实的前期研究基础之上，该项目有望从新的视角（即牦牛瘤胃微生物组）出发，为更加全面地阐述牦牛高原适应基因组学机制提供新的线索。

本项目围绕“肠道微生物组和动物适应性进化”国际学术热点问题，整合宏基因组学、系统生物学和进化生物学等方法，取得以下两个方面的突破性进展：1. 揭示了肠道微生物组趋同进化是同域哺乳动物（牦牛和藏绵羊为例）适应进化的内在驱动力之一，也是动物宿主和其共生肠道微生物长期协同进化的结果，为全面理解自然选择下动物适应性进化的生物学机制提供了新见解；2. 进一步发现熊蜂肠道微生物存在两种保守的生态型，这是继发现哺乳动物（人类和大猩猩）的肠道微生物存在特定生态型后首次在传粉昆虫熊蜂上发现的，表明昆虫和哺乳动物的肠道微生物组是平行进化的。相关研究成果以第一或通讯作者在领域顶级杂志Current Biolology发表SCI论文2篇，明确了肠道微生物组是动物适应性进化研究的新视角。

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