Abstracts (first author)
Functional analysis of differentially expressed genes in the symbiotic association between the pill-bug Armadillidium vulgare and the feminising Wolbachia
Today, there is a wide consensus on the essential role of microbial associations to eukaryote evolution. In most cases, the relationship between host and symbiont is so close that the microorganisms cannot be cultured, making them difficult to study. However, high-throughput sequencing has offered new opportunities for symbiosis research. Due to their widespread association with the Wolbachia endosymbionts, terrestrial isopods represent a model system to understand intimate symbioses. Wolbachia are vertically transmitted facultative bacteria acting as reproductive parasites in isopods, inducing the feminisation of genetic males in the pill bug Armadillidium vulgare. Among the three feminising Wolbachia identified in this host, two strains (wVulC and wVulM) vary in their prevalence and extended phenotypes. wVulC, the most prevalent strain exhibiting the strongest feminising effect, is also the most virulent strain inducing various fitness costs. To decipher the conflicting associations between wVulC, wVulM and A. vulgare, we have constructed cDNA libraries from ovaries and from whole animals challenged by pathogenic intracellular bacteria according to their Wolbachia infection status. RNA from infected and uninfected animals was subjected to RNA-seq sequencing followed by de novo data assembly and annotation. This process generated a library of 33,120 annotated transcripts. Identification of differentially genes (DE) genes as well as overrepresented gene ontology (GO) terms was then carried out using the R packages DESeq and GOSeq. Interestingly the highest number of DE genes was recorded in the animals infected by the less virulent strain wVulM. In most treatments, these DE genes could be assigned to GO categories that are underrepresented when Wolbachia are on board. This study is part of the widest program ImmunSymbArt granted by the French National Research Agency which aims to determine the symbiotic syndrome in four model systems.