四川湍蛙性染色体形成机制

性染色体如何形成是进化生物学领域的研究焦点。对性染色体高度特化的类群（如哺乳类、鸟类等）研究发现，性染色体在演化过程中受到性选择、重组抑制和染色体重排等因素影响，但这些影响在性染色体分化早期类群并不明确。对处于性染色体形成初期类群进行研究，将有助于全面了解性染色体的形成和演化过程。本项目以兼具同形和异形性染色体的四川湍蛙及其近缘种为研究材料，采用单染色体显微切割、单细胞基因组扩增技术和高通量测序等方法以获得大量性染色体上的分子标记，并在此基础上运用染色体涂染及荧光原位杂交技术（FISH）、同源序列和微卫星分析，探索四川湍蛙性染色体的形成和分化。拟回答：（1）四川湍蛙性染色体是否由染色体重排（倒位）方式形成；（2）重组抑制是否存在于性染色体分化初期阶段；（3）性染色体重排是否促进重组抑制，从而强化性染色体的异形趋向。本项目的研究结果有助于了解两栖类以及脊椎动物的性染色体形成过程及演化机制。

The formation and differentiation of sex chromosome have interested to evolutionary geneticists for a long time. From the researches on the lineages with highly morphologically differentiated sex chromosomes (ie. mammals and birds), sex-chromosome evolution was influenced by sexual selection, recombination suppression, and chromosome rearrangement. However, it is unclear that how these factors affect the early stages of sex chromosomes differentiation. Studies of the early stages of their divergence in closely related species can provide insights into the processes of sex chromosome differentiation and evolution. In this study, we plan to get molecular markers on the sex chromosome of Amolops mantzorum, through chromosome microdissection, whole genome amplification (WGA), and high-throughput sequencing of microdissected sex chromosome. Based on these markers, we examine further the levels and patterns of genetic differentiation between sex chromosomes in A. mantzorum and A. kangtingensis. The purpose of this study is to answer three questions: (1) whether recombination suppression really exists in the early stages of sex chromosomes differentiation? (2) whether the heteromorphic sex chromosome of A. mantzorum is caused by chromosome rearrangement (inversion)? (3) if so, what is the substantive effect of inversion on sex chromosome differentiation? The results of this study will help to understanding the processes and patterns of sex chromosome differentiation in amphibians and vertebrates.