Genetic Dissection of Wolbachia Infection in Drosophila Melanogaster

University Of Chicago, Chicago IL

Investigators

Abstract

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.