国内研究

中科院发现裂腹鱼类适应青藏高原极端环境的机制

作者: 来源:中国科学研究院 2017-11-24 我要评论( )

青藏高原是世界上最高的高原,平均海拔高度4500米,面积250万平方公里,有“世界屋脊”和“第三极”之称。由于海拔高,青藏高原的空气干燥、稀薄,太阳辐射强,气温低,氧气含量低

中科院发现裂腹鱼类适应青藏高原极端环境的机制

青藏高原是世界上最高的高原,平均海拔高度4500米,面积250万平方公里,有“世界屋脊”和“第三极”之称。由于海拔高,青藏高原的空气干燥、稀薄,太阳辐射强,气温低,氧气含量低,这些极端环境对于世代生存在青藏高原上的生物来说是很大的考验。近年来,由于第二代测序技术的快速发展,从基因组水平对高原生物低氧适应性机制的研究已取得了许多进展,然而,裂腹鱼类对青藏高原极端环境适应的基因组学研究尚十分有限。

中国科学院水生生物研究所何舜平研究组和多伦多大学教授张兆雷合作,利用转录组测序技术对青藏高原裂腹鱼类进行了研究,对其高原适应性机制有了初步了解。结果表明:(1)高原鱼类显示出全基因组水平的进化速率加快的现象;(2)许多与低氧代谢和能量代谢相关的功能基因在高原鱼类中发生了加速进化;(3)正选择基因以及加速进化基因均显著地富集于与低氧代谢和能量代谢相关的功能分类中。

该研究结果近期在Genome Biology and evolution 在线发表(Comprehensive transcriptome analysis reveals accelerated genic evolution in a Tibet fish, Gymnodiptychus pachycheilus),是在基因组水平研究鱼类对于青藏高原极端环境适应机制的首次报道,具有重要的参考价值。该研究得到中科院先导专项、国家自然科学基金重大研究计划的资助。

原文标题:Comprehensive transcriptome analysis reveals accelerated genic evolution in a Tibet fish,Gymnodiptychus pachycheilus

Elucidating the genetic mechanisms of organismal adaptation to the Tibetan Plateau at a genomic scale can provide insights into the process of adaptive evolution. Many highland species have been investigated and various candidate genes that may be responsible for highland adaptation have been identified. However, we know little about the genomic basis of adaptation to Tibet in fishes. Here we performed transcriptome sequencing of a schizothoracine fish (Gymnodiptychus pachycheilus) and used it to identify potential genetic mechanisms of highland adaptation. We obtained totally 66,105 assembled unigenes, of which 7,232 were assigned as putative one-to-one orthologs in zebrafish. Comparative gene annotations from several species indicated that at least 350 genes lost and 41 gained since the divergence between G. pachycheilus and zebrafish. An analysis of 6,324 orthologs among zebrafish, fugu, medaka, and spotted gar identified consistent evidence for genome-wide accelerated evolution in G. pachycheilus and only the terminal branch of G. pachycheilus had an elevated Ka/Ks ratio than the ancestral branch. Many functional categories related to hypoxia and energy metabolism exhibited rapid evolution in G. pachycheilus relative to zebrafish. Genes showing signature of rapid evolution and positive selection in the G. pachycheilus lineage were also enriched in functions associated with energy metabolism and hypoxia. The first genomic resources for fish in the Tibetan Plateau and evolutionary analyses provided some novel insights into highland adaptation in fishes and served as a foundation for future studies aiming to identify candidate genes underlying the genetic bases of adaptation to Tibet in fishes.

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裂腹鱼,高原,极端环境

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