Molecular genetics of Drosophila hybrid lethality

描述(申请人提供)：最近的研究表明，正向选择正在推动物种间生殖隔离所涉及的基因的快速分化。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)最近发现，Hmr基因导致了果蝇与其近亲物种之间的F1杂交致死，并暗示第二个基因LHR也参与了这种致死。在这项建议的目的1中，我们建议克隆LHR基因，以检验杂交致死是由黑腹金龟Hmr基因和兄弟种LHR基因相互作用引起的假说。我们将尝试完全在/)内重建种间不亲和性。使用转基因构建物的黑猩猩菌株。为了了解LHR在物种中的功能，我们还将在黑腹毛虫中创建LHR功能缺失突变。目的2从种内功能和杂交功能两个方面探讨分子进化与ct HmR功能特性的关系。我们将对HMR功能缺失突变体和种间杂交进行发育分析，使用分子进化和群体遗传学技术来识别HMR在选择下可能分化的区域和密码子，然后使用转基因分析来检验这些进化分析得出的假设的功能后果。我们还将调查LHR是否在黑腹金龟及其近缘物种之间的选择下发生了分化。在目标3中，将对黑腹金丝猴进行基因筛查，以确定与HMR和LHR相互作用导致杂交致死的新基因。即将公布的来自近亲物种拟果蝇和其他几个果蝇物种的全基因组序列将极大地增强这一提议作为测试序列分歧的功能后果的模型的技术可行性和潜在影响。

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.