飞蝗对青藏高原低氧极端环境遗传适应的多基因互作机制

Different from other animals, insect species transport and diffuse O2 through trachea system. Therefore insects may have evolved different strategies to adapt to hypoxia. Tibetan populations of the locust species, Locusta migratoria, have presented distinct morphological, physiological and biochemical traits that have evolved in over ten thousand years’ history of their colonization of the Tibetan plateau. However, no study has been reported about the genetic mechanisms underlying insects’ adaptation to extreme hypoxic environment. Here based on improved methods for transcriptome sequencing and analysis, we will screen potential evolutionary signals and pathways subject to strong positive selection by comparing the SNP and gene expression between the Tibetan and lowland populations on a genomic level, to identify genes and loci that are highly associated with hypoxia adaptation by assoication study, finally to reveal the molecular mechanisms underlying gene expression or functional changes of key genes through in vitro and in vivo genotype-phenotype study. Based on our previous study on the Tibetan locusts and the respiratory characteristics of insects, we will focus on the study of genes involved in trachae development, respiratory-chain electric transportation and oxidative phosphorylation, and regulation of hemocyanin expression. As a result, our study will be the first to uncover the genetic and molecular mechanisms, including regulatory mechanis, by which insects adapted to eternal extreme hypoxic environments in the Tibetan plateau.

与其他生物不同，昆虫通过气管系统直接将氧气运输和扩散到细胞，因此，昆虫可能采用特定的机制适应低氧环境。飞蝗西藏种群在十多万年对青藏高原环境的适应过程中，进化出独特的形态和生理生化特征。但目前还没有对昆虫适应高原低氧极端环境的遗传机制的报道。本项目将基于优化的转录组测序分析，比较飞蝗西藏种群和平原种群全基因组水平的序列SNP变异和基因表达差异，筛选受自然选择的进化信号和潜在作用通路；通过关联分析，发现与高原低氧适应高度相关的基因和位点；对关键候选基因进行体内体外的基因型-表型关系实验，确定导致基因表达或者功能改变的分子机制。基于前期对西藏飞蝗生理生化研究基础和飞蝗呼吸代谢特性，本项目还将重点考察参与飞蝗气管发育、呼吸链电子传递和氧化磷酸化及血蓝蛋白表达调节的基因。该研究将首次在基因组水平揭示昆虫这一大类生物适应高原低氧极端环境的遗传和分子机理，包括调控进化机制。

与其他生物不同，昆虫通过气管系统直接将氧气运输和扩散到细胞，因此，昆虫可能采用特定的机制适应低氧环境。飞蝗西藏种群在十多万年对青藏高原环境的适应过程中，进化出独特的形态和生理生化特征。本项目第一次对昆虫适应高原低氧极端环境的遗传机制开展研究。本项目基于种群基因组重测序，比较了飞蝗西藏种群和平原种群全基因组水平的序列SNP变异和基因表达差异，筛选受自然选择的进化信号和潜在作用通路；对关键候选基因进行体内体外的基因型-表型关系实验，确定导致基因表达或者功能改变的分子机制。结果发现，高原飞蝗与平原飞蝗种群间发生明显的遗传分化。发现受选择基因集中在细胞大分子代谢功能方面。深入分析发现飞蝗HIF-а在西藏飞蝗发生重要的突变，该突变受自然选择。HIF-а具有与人类接近的功能域。飞蝗HIF-а能响应低氧诱导，显著上调其在mRNA水平和蛋白水平的表达。而且，HIF-а在其抑制调节因子PHD表达抑制后，HIF-а表达显著上调。我们另发现，昆虫胚胎呼吸需要一种呼吸蛋白，即血蓝蛋白（hemocyanin）的参与。血蓝蛋白响应低氧诱导高表达，而且西藏飞蝗表达显著高于平原飞蝗。研究揭示西藏飞蝗通过血蓝蛋白的高表达来适应低氧环境。该研究将首次在基因组水平揭示昆虫这一大类生物适应高原低氧极端环境的遗传和分子机理。