Transcription profiling of Drosophila infected with Wolbachia

The Drosophila-Wolbachia system is being used to study the molecular nature of the interactions between a host and a symbiont. This system offers a unique opportunity for such a study since the Drosophila genome sequence is available, several Wolbachi genomes will also be available soon and there are at least three known Wolbachia strains infecting Drosophila: a) mod+ strain that induces cytoplasmic incompatibility, b) mod- strain that cannot induce cytoplasmic incompatibility, and c) popcorn strain, a virulent strain which reduces in half the adult lifespan of Drosophila due to its massive proliferation in adult brain. The Drosophila-Wolbachia interaction manifests itself in 3 main ways; first, destruction of the CNS in infected adults, second, induction of some kind of modification or imprinting in the male germ-line resulting in an early failure in embryonic development, (cytoplasmic incompatability (CI)) and third, modification of the female germ-line resulting in resistance to modified sperm. We are interested in identifying Drosophila genes with changes in expression due to Wolbachia infection. We have generated a series of isogenic fly lines (those being used in the IGF P-element project) which we have infected with Wolbachia strains, infection is readily cured by growth on medium containing tetracycline. Thus, we have equivalent genetic background with and without the parasite. We have tested all of the transgenic lines for the level of CI and find strain-specific levels ranging from 0-50%. We also have a strain of D. simulans that shows over 95% CI. Plan: For our initial experiments we wish to make 4 comparisons, in all cases 2 day old males will be collected and for each comparison we will isolate 3 independent biological replicates: Melanogaster no CI [tet] x Melanogaster no CI [+wol] Melanogaster high CI [tet] x Melanogaster high CI [+wol] We will therefore identify genes with changed expression levels in the male upon Wolbachia infection by comparing the melanogaster strains with high or no CI in the presence of tetracycline and Wolbachia. We also hope to identify similar genes in simulans (where we expect the magnitude of the effect to be larger), differences between melanogaster and simulans are controlled for in the mel v sim comparison.