Rescue of the bag-of-marbles hypomorph fertility defect by Wolbachia pipientis is associated with expression changes in genes associated with ubiquitin and histone lysine methylation.

Wolbachia pipientis are maternally transmitted endosymbiotic bacteria commonly found in arthropods and nematodes. These bacteria manipulate reproduction of the host to increase their transmission using mechanisms, such as cytoplasmic incompatibility, that favor infected female offspring. The underlying mechanisms of reproductive manipulation by W. pipientis continue to be the subject of ongoing research. Interestingly, W. pipientis infection partially rescues female fertility in flies containing hypomorphic mutations of bag of marbles (bam) in D. melanogaster, which functions in germline stem cell (GSC) maintenance and differentiation. Our RNA-seq analysis using the W. pipientis infected relative to uninfected bam hypomorph genotype showed differential expression for many of bam’s genetic and physical interactors. The bam hypomorph showed enrichment of ubiquitination and histone lysine methylation genes, some of which have fertility rescue by W. pipientis when knocked down in the WT genotype. Our results show that W. pipientis interacts with ubiquitination and histone lysine methylation genes which could be integral to the bam hypomorph fertility rescue. To study whether the rescue of bam hypomorph (partial loss of function of bam) fertility by Wolbachia pipientis variants (wMel2a, wMel3, wMelCS2a, and wMelCS2b) in D. melanogaster occurs at the gene expression level, we conducted RNA-seq in bam hypomorph and WT ovaries followed by a differential expression analysis using uninfected controls.. We used unmated three-day old, mated three-day old and mated-six day old flies from each genotype to determine if the age-dependent rescue by W.pipientis of the bam hypomorph is due to gene expression differences in the host.