野生金丝猴肠道微生物对环境适应性的研究

An ability to adapt to spatial and temporal dietary variation is important for allowing animals to survive in their natural environments. For instance, folivorous primates rely on fermentation by a specialist gut microbiota in order to digest plant foodstuffs that vary in their availability to hosts in space and time. Although there are many dietary adaptations that operate via multiple complex mechanisms, each folivorous primate species must have evolved a stable but dynamic process of extracting nutrient components from a variable plant-based diet. However, although the gut microbial communities of folivorous primates have evolved to process the multiple nutrients ingested by their hosts, it remains unclear how these gut microbiomes respond to variation in nutrient intake according to temporal and spatial variation in host foodstuff consumption. Such an understanding is, however, important for primate conservation, particularly in recognizing the fluctuations of nutrient intakes following environmental changes. We will use metagenomic analysis of faecal samples collected from different wild golden snub-nosed monkey populations in the Qinling Mountains, samples that will also capture seasonal dietary variation. This project will use qualitative analytical tools to measure the dynamic changes and functions of the gut microbiome community structure. We will also measure the responding gene profiles of the gut microbiomes through seasonal changes to the proportions of the three major dietary macronutrients ingested by the monkeys, fats, proteins and carbohydrates. By determining gene function, we will build a mechanistic picture of how these gut microbiomes adapt to temporal variation in the nutrients ingested by their hosts. This project will thus show how essential gut microflora are likely to react to predicted changes in spatial and temporal variation in the diets of their endangered, endemic monkey hosts changes caused by factors such as deforestation and climate change.

动物对食物的适应是其对环境适应的关键。食叶灵长类依靠消化道微生物群落的发酵，来协助它们适应叶食性的环境。虽然食叶灵长类食物种类复杂，但是动物的营养成分摄入却呈动态的稳定性。尽管我们已经发现食叶灵长类肠道微生物群落在长期进化中对宿主摄入的营养物质有了适应，可以发酵降解食入的纤维，但是对于肠道微生物如何应对养分摄入的波动的机制并不清楚。而野生动物研究和保护实践中，我们已经发现金丝猴经常面临如季节性、环境变迁时养分摄入波动的冲击，但对肠道微生物应答的机制并仍清楚。为此，我们在营养定量研究的基础上，拟通过对野生金丝猴粪便样本动态收集和宏基因组测序分析，掌握肠道微生物群落组成、结构与功能的动态变化规律；通过对野生金丝猴对三大营养成分的摄入比例的调节，研究肠道微生物的应答关系，进而揭示动物肠道微生物适应宿主食物波动的机制，回答食叶灵长类动物肠道微生物如何适应宿主环境食物波动这一重要的理论和实践问题。

动物消化系统的结构因食性特征有相应的特化。植食性哺乳动物在漫长的进化历史中，在消化系统内与微生物群落共生，借助其来发酵降解食物中的结构性碳水化合物，并将其转化成自身可以吸收的能量物质挥发性脂肪酸和其它营养成分。植食性哺乳动物的营养和能量摄取水平很大程度决定于肠道微生物群落的稳定性和发酵能力。.这些依靠肠道微生物发酵获取营养的动物对食性的适应，其实是对摄入的营养成分组成的适应。但是，哺乳动物的食物和养分摄入是动态变化的，肠道微生物要获得稳定可靠的营养产出供寄主需要，必须要动态的应答这种动态变化。这种应答机制是肠道微生物群落与宿主协同进化的关系研究中的核心问题，这个问题关键是要阐明宿主营养摄入和肠道微生物群落二者动态变化时的协同关系，但这也一直是研究的难点。.对此，本研究在营养定量研究的基础上，通过对野生金丝猴粪便样本动态收集和宏基因组测序分析，掌握肠道微生物群落组成、结构与功能的动态变化规律，研究肠道微生物的应答关系，进而揭示动物肠道微生物适应宿主食物波动的机制，回答食叶灵长类动物肠道微生物如何适应宿主环境食物波动这一重要的理论和实践问题。.研究发现川金丝猴蛋白质优先的营养平衡模式，阐明了秦岭金丝猴生活生存于在高寒高海拔山区根本原因是个体能在冬季通过摄入大量碳水化合物来实现能量平衡的适应策略。金丝猴的胃和盲肠与其它疣猴一样，体积并没有异常，但是进化出了更大的大肠。并且前后肠具有消化纤维的活性酶，且纤维在前后肠均可以被降解。前后肠内细菌的组成和功能特征具有显著差异。前肠的细菌种属较少，但之间连接更紧密，正向协同关系更多，说明前肠的微生物群落功能可能更加专一和高效，后肠微生物种类更多具有更广泛的代谢功能，可以补充前肠的代谢。金丝猴通过前后肠的互补协同作用充分提高了金丝猴对营养成分的吸收。研究系揭示了金丝猴冬季生理适应机制，还对当前大量仅利用后肠粪便做肠道微生物协同进化研究提供重要借鉴。