蝙蝠翼手形成的分子机制研究

Bats are the only mammals capable of flight and form the second largest mammalian order. The most important feature of bats in morphology is a pair of wings. Bat wing digits which raise broad patagia are significantly elongated and the longest one is longer than its head-body length. However, the molecular mechanism of bat wing formation is unclear and becomes an important research problem in the field of devlopmental and evolutionary biology. In this project, we will perform mRNA-seq for the samples from different embryonic stages and wing positions in the great leaf-nosed bat (Hipposideros armiger). In a genomic scope, we will analyze the gene expression profiles and gene coding sequences. Key genes that regulate digit elongation and patagium formation will be found by the analysis of gene differential expression of the digits and webs. Genes that control limb development and have been under positive selections will be found by molecular and evolutionary analysis using the sequences from bats and other mammals. In the meantime, the significantly differentially expressed genes will be confirmed by in situ hybridization in Schreiber's long-fingered bat (Miniopterus schreibersii) and mouse. Finally, we will summarize the molecular mechanism of bat wing formation in the aspects of gene expression and molecular evolution, and compare it with the molecular mechanism of elongated foot digits in jerboas. These results will contribute to the researches in the development and evolution of mamalian limbs, as well as convergent evolution.

蝙蝠是唯一真正会飞行的、第二大哺乳动物类群，其最明显的形态特征是具有一对翅膀样的翼手。它的手指显著延长，最长的第三指超过自身的头体长，手指和臂膀撑起宽阔的翼膜。然而，蝙蝠翼手形成的分子机制仍然不明确，是发育与进化生物学领域的一个重要问题。本项目拟将大蹄蝠胚胎期翼手的各个部位进行高通量转录组测序（mRNA-seq），在基因组范围内做基因表达谱和编码区序列两方面的分析。通过延长指和非延长指/趾、翼膜和脚趾间膜的基因差异表达分析，发现导致蝙蝠手指延长和翼膜形成的关键基因；通过蝙蝠和其它哺乳动物基因序列的分子进化分析，发现蝙蝠加速进化的翼手发育调控基因。同时，在长翼蝠和小鼠中，将时空表达差异极显著的基因做原位杂交验证试验。最后，从蝙蝠基因表达谱和序列两方面的进化，总结出蝙蝠翼手形成的分子机制，并与跳鼠脚趾延长的分子机制进行比较，为哺乳动物四肢发育与进化和趋同进化的研究提供有益借鉴。

蝙蝠是唯一真正会飞行的、第二大哺乳动物类群，其最明显的形态特征是具有一对翅膀样的翼手。它的手指显著延长，最长的第三指超过自身的头体长，手指和臂膀撑起宽阔的翼膜。然而，蝙蝠翼手形成的分子机制仍然不明确，是发育与进化生物学领域的一个重要问题。本项目将大蹄蝠胚胎期翼手的各个部位进行高通量转录组测序（mRNA-seq），在基因组范围内做基因表达谱的分析。通过延长指和非延长指/趾、翼膜和脚趾间膜的基因差异表达分析，发现导致蝙蝠手指延长和翼膜形成的关键基因，并且在长翼蝠和小鼠中将时空表达差异极显著的基因做原位杂交验证试验，包括在翼手发育时高表达的5’HoxD基因、Tbx3和后肢高表达的Fam5c基因等。最后，结合近期蝙蝠翼手发育的研究进展，总结出蝙蝠翼手形成的分子机制。