Project description: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.
Project description:Wolbachia is a maternally transmitted bacterium that manipulates arthropod and nematode biology in myriad ways. The Wolbachia strain colonizing Drosophila melanogaster creates sperm-egg incompatibilities and protects its host against RNA viruses, making it a promising tool for vector control. Despite successful trials using Wolbachia-transfected mosquitoes for Dengue control, knowledge of how Wolbachia and viruses jointly affect insect biology remains limited. Using the Drosophila melanogaster model, transcriptomics and gene expression network analyses revealed pathways with altered expression and splicing due to Wolbachia colonization and virus infection. Included are metabolic pathways previously unknown to be important for Wolbachia-host interactions. Additionally, Wolbachia-colonized flies exhibit a dampened transcriptomic response to virus infection, consistent with early blocking of virus replication. Finally, using Drosophila genetics, we show Wolbachia and expression of nucleotide metabolism genes have interactive effects on virus replication. Understanding the mechanisms of pathogen blocking will contribute to the effective development of Wolbachia-mediated vector control programs.
Project description:Using microarray-based comparative genome hybridizations (mCGH), the genomic content of Wolbachia pipientis wMel from Drosophila melanogaster was compared to the Wolbachia from D. innubila (wInn), D. santomea (wSan), and three strains from D. simulans (wAu, wRi, wSim).
Project description:The molecular mechanisms by which parasites mediate host behavioral changes remain largely unexplored. Here, we examine Drosophila melanogaster infected with Wolbachia, a symbiont transmitted through the maternal germline, and find Wolbachia infection increases female receptivity to male courtship and hybrid mating. Wolbachia colonize regions of the larval and adult female brain controlling sense perception and behavior. Quantitative global proteomics identified 177 differentially abundant proteins in infected female larval brains. Genetic alteration of the levels of three of these proteins in adults, the metabotropic glutamate receptor mGluR, the transcription factor TfAP-2, and the odorant binding protein Obp99b, each mimicked the effect of Wolbachia on female receptivity. Furthermore, >700 Wolbachia proteins were detected in infected brains. Through abundance and molecular modeling analyses, we distinguished several Wolbachia-produced proteins as potential effectors. These results identify networks of host and Wolbachia proteins that modify behavior to promote mating success and aid the spread of Wolbachia.
Project description:Transcriptional profiling of Drosophila melanogaster larval testes with and without the wMel strain of Wolbachia and found that 296 genes had at least a 1.5 fold change [q-value (%)<5%] in transcript levels, with 167 genes up-regulated and 129 genes down-regulated when comparing Wolbachia-infected flies to uninfected ones. Differential expression of genes related to metabolism, immunity, reproduction and other functions were observed.
Project description:Laodelphax striatellus is naturally infected with the Wolbachia strain wStri, which significantly increase the fecundity of its host. Wolbachia-infected females produce 30%–40% more eggs than Wolbachia-uninfected females. MicroRNAs (miRNAs) are a class of endogenous non-coding small RNAs that play critical roles in the regulation of gene expression at post-transcriptional level. Here we report the differentially expressed miRNAs between Wolbachia-infected and Wolbachia-uninfected strains of L. striatellus ovaries. Our data may be helpful to explore the molecular mechanisms by which Wolbachia increase the fecundity of Laodelphax striatellus.
Project description:Wolbachia pipientis is a worldwide bacterial parasite of arthropods that infects host germline cells and manipulates host reproduction to increase the ratio of infected females, the transmitting sex of the bacteria. The most common reproductive manipulation, cytoplasmic incompatibility (CI), is expressed as embryonic death in crosses between infected males and uninfected females. Specifically, Wolbachia modify developing sperm in the testes by unknown means to cause a post-fertilization disruption of the sperm chromatin that incapacitates the first mitosis of the embryo. As these Wolbachia-induced changes are stable, reversible, and affect the host cell cycle machinery including DNA replication and chromosome segregation, we hypothesized that the host methylation pathway is targeted for modulation during cytoplasmic incompatibility because it accounts for all of these traits. Here we show that infection of the testes is associated with a 55% increase of host DNA methylation in Drosophila melanogaster, but methylation of the paternal genome does not correlate with penetrance of CI. Overexpression and knock out of the Drosophila DNA methyltransferase Dnmt2 neither induces nor increases cytoplasmic incompatibility. Instead, overexpression decreases Wolbachia titers in host testes by approximately 17%, leading to a similar reduction in CI levels. Finally, strength of CI induced by several different strains of Wolbachia does not correlate with levels of DNA methylation in the host testes. We conclude that DNA methylation mediated by Drosophila's only known methyltransferase is not required for the transgenerational sperm modification that causes CI. Genomic DNA was extracted from pooled samples of Drosophila melanogaster adult testes. One sample from Wolbachia-infected males and one from uninfected males. Bisulfite sequencing was used to determine whether Wolbachia infection affects host DNA methylation in the testes.