Genetic Dissection of Wolbachia Infection in Drosophila Melanogaster

Wolbachia pipientis是已知最广泛的内共生微生物之一。首先在尖音库蚊复合群的蚊子中发现，此后在超过20%的昆虫物种和约25%的用于遗传研究的黑腹果蝇中发现。沃尔巴克氏体专门操纵宿主的繁殖。在果蝇中，沃尔巴克氏体主要导致细胞质不相容性（CI），一种生殖隔离的形式。CI的表达使得感染的雄性在与未感染的雌性交配时不能生育后代。当受感染的雄性正常交配，转移精子，精子使卵子受精时，卵子不能完成核配而死亡。未受感染的雄性和受感染的雌性之间的相互杂交是可行的，但由于沃尔巴克氏体通过雌性垂直传播，所有产生的后代都被感染。该研究项目将试图了解黑腹果蝇睾丸中沃尔巴克氏体分布的遗传基础以及由此产生的对CI的影响。缺陷定位将确定基因座的沃尔巴克氏体分布和密度的大影响D。黑腹睾丸将对缺乏的库存进行筛选，以确定是否存在沃尔巴克氏体。这些菌株与不同模式的沃尔巴克氏体分布将进一步研究他们的能力（或不能），以导致CI以及宿主的差异细菌分布的遗传基础。在通过缺陷作图鉴定重要的候选基因座之后，将研究具有不同水平等位基因对细菌分布和CI的影响。参与确定沃尔巴克氏体分布模式的基因和生化途径的鉴定将促进对沃尔巴克氏体如何操纵果蝇宿主生殖和精子发生的理解。它还可能提供线索，说明当沃尔巴克氏体感染亲缘关系较远的昆虫时，特别是引起人类疾病的昆虫害虫（例如，蚊子传播的疟疾疾病）时，是什么途径被操纵的。这些知识也将有助于利用沃尔巴克氏体设计有效的害虫管理方案。

Wolbachia pipientis is one of the most widespread endosymbiotic microorganisms known. First characterized in mosquitoes of the Culex pipiens complex, it has since been found in greater than 20% of insect species and about 25% of Drosophila melanogaster used in genetic research. Wolbachia has specialized in the manipulation of host reproduction. In Drosophila, Wolbachia primarily causes cytoplasmic incompatability (CI), a form of reproductive isolation. The expression of CI renders infected males unable to father offspring when mated to uninfected females. While infected males mate normally, transfer sperm and the sperm fertilize the egg, the egg fails to complete karyogamy and dies. Reciprocal crosses between uninfected males and infected females are viable, but since Wolbachia are transmitted vertically through the female, all resulting progeny are infected. The research project will attempt to understand the genetic basis of Wolbachia distribution in Drosophila melanogaster testes and the resulting effects on CI. Deficiency mapping will identify loci with large effects on Wolbachia distribution and density within D. melanogaster testes. Deficiency stocks will be screened for the presence of Wolbachia. Those strains with dissimilar patterns of Wolbachia distribution will be studied further for their ability (or inability) to cause CI as well as the for the host genetic basis of differential bacterial distribution. Following identification of important candidate loci through deficiency mapping, alleles with different levels of penetrance will be studied for their impact on bacterial distribution and CI. The identification of genes and biochemical pathways involved in determining Wolbachia distribution patterns will advance the understanding of how Wolbachia manipulate host reproduction in Drosophila and spermatogenesis in general. It may also provide clues as to what pathways are manipulated when Wolbachia infect more distantly related insects, particularly insect pests that cause human diseases (for example, malarial diseases transmitted by mosquitoes. Such knowledge will also aid in the design of effective pest management programs utilizing Wolbachia.