Molecular genetics of Drosophila hybrid lethality

描述（由申请人提供）：最近的研究表明，积极选择正在推动物种之间生殖隔离相关基因的快速分化。因此，生殖隔离基因的详细特征将有助于我们了解物种特有的特征和适应以及物种形成过程本身。我们最近已经表明，Hmr基因导致黑腹果蝇和它的兄弟姐妹之间的Fl杂交致死；研究表明，另一种基因Lhr也与这种致命性有关。在本提案的目标1中，我们提出克隆Lhr基因，以验证杂交致死是由黑胃D. Hmr基因和兄弟种Lhr基因相互作用引起的假设。我们将尝试在/)中完全重构种间不兼容性。使用转基因结构的黑腹菌菌株。我们还将在D. melanogaster中创建Lhr的功能缺失突变，以了解Lhr在物种中的功能。目的2将探讨分子进化与Hmr在种内和杂交功能方面的功能特性之间的关系。我们将对Hmr失去功能的突变体和种间杂交体进行发育分析，使用分子进化和群体遗传技术来识别Hmr可能在选择下分化的区域和密码子，然后使用转基因分析来测试从这些进化分析中得出的假设的功能后果。我们还将研究Lhr是否在黑腹龙及其兄弟物种之间的选择中分化。在第3阶段，将对黑腹龙进行基因筛选，以确定与Hmr和Lhr相互作用导致杂交致死的新基因。即将到来的来自兄弟物种D. simulans以及其他几个果蝇物种的全基因组序列将极大地提高技术可行性和该提议作为测试序列分化功能后果的模型的潜在影响。

DESCRIPTION (provided by applicant): Recent studies suggest that positive selection is driving rapid divergence of genes involved in reproductive isolation between species. Detailed characterization of reproductive isolation genes will therefore contribute to our knowledge both of species-specific traits and adaptations and of the speciation process itself. We have) recently shown that the gene Hmr causes Fl hybrid lethality between Drosophila melanogaster and its sibling; species, and suggested that a second gene, Lhr, is also involved in this lethality. In Aim 1 of this proposal we propose to clone the Lhr gene in order to test the hypothesis that hybrid lethality is caused by the interaction of the D. melanogaster Hmr gene and the sibling-species Lhr gene. We will attempt to reconstitute the interspecific incompatibility entirely within /). melanogaster strains using transgenic constructs. We will also create a loss-of-function mutation in Lhr in D. melanogaster in order to understand the function of Lhr within species. Aim 2 will explore the relationship between the molecular evolution and the functional properties ct Hmr with respect to its intraspecific and hybrid functions. We will do developmental analyses of Hmr loss of- function mutants and of interspecific hybrids, use molecular evolutionary and population genetic techniques to identify regions and codons of Hmr that may be diverging under selection, and then use transgenic assays to test the functional consequences of hypotheses derived from these evolutionary analyses. We will also investigate whether Lhr has diverged under selection between D. melanogaster and its sibling species. In Aim 3 a genetic screen will be done in D. melanogaster to identify new genes that interact with Hmr and Lhr to cause hybrid lethality. The forthcoming whole-genome sequence from the sibling species D. simulans as well as several other Drosophila species will greatly enhance both the technical feasibility and the potential impact of this proposal as a model for testing functional consequences of sequence divergence.