MOLECULAR EVOLUTION OF A HOMEODOMAIN GENE OF SPECIATION

作为通向了解物种这一长期目标的第一步 在分子水平上的分化，我们计划研究最近 克隆了果蝇生殖隔离基因。 毛叶石杉适当染色体区域的导入 含有消耗臭氧层物质的基因座会导致拟态石斑菌(Perez et 艾尔1993年；Perez和Wu 1995年)。最近的进展表明，消耗臭氧层物质是一个 含有同源结构域的基因。这种基因的不同寻常之处在于它的 同源结构域经历了极快的氨基酸替换 果蝇。它的快速发展加上新收购的 在雄性生殖系中的表达表现为杂交雄性不育。这个 这项提议的目的是：1)研究分子基础 种系转化导致的ods分化：杂交的两个原因 通过外显子探索不育性和消耗臭氧层物质的正常功能 转基因研究中的交换。2)研究基因表达模式 应用原位抗体染色检测ODS值与其表达的相关性 在雄性生殖细胞中，快速序列进化和遗传 将探讨导致不育的不亲和性。3)分析 消耗臭氧层物质同源域蛋白的DNA结合特性：这将是一个 向最终鉴定下游基因迈出的第一步。4) 为了研究消耗臭氧层物质的分子进化和种群遗传学： 将是第一次对起关键作用的基因进行DNA序列分析 处于生殖隔离状态。

As a first step toward the long term goal of understanding species differentiation at the molecular level, we plan to study the recently cloned gene of reproductive isolation in Drosophila, Odysseus (Ods). Introgression of an appropriate D. mauritiana chromosomal region containing the Ods locus causes male sterility in D. simulans (Perez et al. 1993; Perez and Wu 1995). Recent progress suggests that Ods is a homeodomain-containing gene. This gene is unusual in that its homeodomain has experienced extremely rapid amino acid substitution in Drosophila. Its rapid evolution coupled with the newly acquired expression in male germline is manifested as hybrid male sterility. The objectives of this proposal are: 1) To investigate the molecular basis of Ods divergence by germline transformation: Both the causes of hybrid sterility and the normal functions of Ods will be explored by exon swapping in transgenic studies. 2) To study the expression pattern of Ods by in situ antibody staining: The correlation between the expression in male germ cells, the rapid sequence evolution and the genetic incompatibility leading to sterility will be explored. 3) To analyse the DNA binding property of the Ods homeodomain protein: This will be a first step toward the eventual identification of downstream genes. 4) To study the molecular evolution and population genetics of Ods: This will be the first DNA sequence analysis of a gene that plays a key role in reproductive isolation.