Molecular Genetics of Drosophila Hybrid Lethality

项目摘要 当分化的种群变得生殖隔离时，新物种就会形成。一 造成这种隔离的原因是杂交不亲和性，种间的不育性和致死性 混血儿。这项建议研究了两个先前发现的基因，它们相互作用，导致 果蝇品种黑腹果蝇与果蝇D。 人形动物。对这两个基因的序列分析表明，它们是在 适应性进化，在其他杂交不亲和基因中也观察到了这种模式。 识别导致这种分子进化模式的特定选择性作用力将 因此有助于阐明物种形成的生物学原因。这项建议是基于 最近的发现，这些果蝇杂交不亲和基因需要 抑制转座元件，可以动员的自私DNA，达到高拷贝数， 并对真核生物基因组造成重大破坏。一系列的遗传和分子 这里提出了检测这些基因如何在抑制中发挥作用的方法。 转座元件，包括描绘全基因组范围的转座模式 突变系。其他表型分析将调查这些基因是如何影响生育的。 以及在它们自己的寄主物种内的减数分裂表现。然后，注意力将转向一个 综合努力以确定序列分歧和适应性进化之间 物种已经改变了这些基因的特定功能。可转置的元素是 包括人类在内的真核生物自发突变和DNA损伤的主要原因。 拟议的研究将提供一个高分辨率的视角，了解转座子是如何 负载有助于宿主基因的进化和物种间的生殖隔离。

Project Summary New species form when diverging populations become reproductively isolated. One cause of this isolation is hybrid incompatibility, the sterility and lethality of interspecific hybrids. This proposal investigates two previously identified genes that interact to cause lethality in hybrids between the fruit fly species Drosophila melanogaster and D. simulans. Sequence analysis of both genes shows that they have evolved under adaptive evolution, a pattern also observed with other hybrid incompatibility genes. Identifying the specific selective forces causing this pattern of molecular evolution will therefore help elucidate the biological causes of speciation. This proposal is based on the recent discovery that these Drosophila hybrid incompatibility genes are required to repress transposable elements, selfish DNAs that can mobilize, reach high copy number, and cause significant damage to eukaryotic genomes. A range of genetic and molecular assays are proposed here to identify how these genes function in repressing transposable elements, including profiling the genome-wide pattern of transposition in mutant lines. Other phenotypic assays will investigate how these genes affect fertility and meiotic performance within their own host species. Attention will then turn to an integrated effort to determine how sequence divergence and adaptive evolution between species has altered specific functions of these genes. Transposable elements are a major cause of spontaneous mutation and DNA damage in eukaryotes including humans. The proposed studies will provide a high resolution view of how transposable element load contributes to host gene evolution and reproductive isolation between species.