For many of us, when we think of microbiomes, our first thoughts are probably about the beneficial microorganisms that live in our guts. But now, researchers from Japan and US have discovered how the microbes living in fruit flies can enhance their reproduction. In a recently published study in Communications Biology, the research group has revealed that microbes in the fruit fly microbiome are involved in controlling the germline stem cells that form eggs, as well as subsequent egg maturation, in female fruit flies.

The researchers investigated the effects of microbes on oogenesis in fruit flies, Drosophila melanogaster. Using genetic analysis, the team revealed that microbes boost oogenesis by both accelerating the division of ovarian cells and suppressing programmed cell death, as well as increasing the production of germline stem cells (GSC) by enhanced cell division and eventually increasing the number of mature eggs in females. We discovered that the microbes' enhancement of reproductive function was controlled by the activation of the hormonal pathways for ecdysone and juvenile hormones in the germline stem cells -- the cells that develop into eggs.

The researchers found that the ecdysone pathway may be an important mediator for a microbe-induced increase of GSCs and egg maturation. Meanwhile, the juvenile hormone pathway is involved only in GSC proliferation, which indicates that the hormonal pathways are activated during different stages of oogenesis. Specifically, the findings from this study will contribute to the understanding of how microbes boost their host's reproductive processes, which will open the door for new methods to improve fertility and infertility treatment.