Microbiomes are often associated with the beneficial microorganisms that live in our gut. However, researchers from Japan and the USA have discovered how microbes living in fruit flies can enhance their reproduction.
A study published in Communications Biology revealed that microbes in the fruit fly microbiome are involved in controlling germline stem cells that form eggs and subsequent egg maturation in female fruit flies.
The microbiome, the community of microorganisms that live in and on a host, plays a significant role in enabling vital functions, including regulating metabolism, nutrient uptake, and reproduction. However, the specific molecular mechanisms that allow microbes to control germline maturation within an organism continue to be a mystery.
„We propose that microbes control different stages of oogenesis, which regulate the production of eggs in the ovary,“ said the study’s lead author, Ritsuko Suyama. „They can do this by altering hormone levels and their subsequent signaling pathways, thus promoting the host’s fertility under poor nutrition.“
The researchers examined the effects of microbes on oogenesis in fruit flies, Drosophila melanogaster. Through genetic analysis, the team demonstrated that microbes promote oogenesis by accelerating both the division of ovarian cells and suppressing programmed cell death, as well as increasing germline stem cell (GSC) production through enhanced cell division and ultimately increasing the number of mature eggs in females.
„We found that the enhancement of microbial reproductive function was controlled by activating the hormone pathways for ecdysone and juvenile hormones in germline stem cells, the cells that develop into eggs,“ said senior author Toshie Kai.
Ecdysone is a steroid hormone that regulates insect molting. The researchers found that the ecdysone pathway could be a key mediator for a microbial-induced increase in GSCs and egg maturation. Meanwhile, the juvenile hormone pathway is only involved in GSC proliferation, indicating that the hormone pathways are activated at different stages of oogenesis.
„Our results demonstrate that environmental microbes can enhance the host’s reproduction by controlling hormone secretion and boosting oogenesis in their hosts,“ added Suyama.
These new findings on host-microbe interactions could open up new avenues to improve reproductive health, such as through novel probiotic treatments. In particular, the results of this study will contribute to understanding how microbes boost their host’s reproductive processes, paving the way for new methods to improve fertility and treat infertility.
Suyama, R., et al. (2023). Microbes control Drosophila germline stem cell proliferation and egg maturation via hormonal pathways. Communications Biology. doi.org/10.1038/s42003-023-05660-x.