Romoli Ottavia, Serrato-Salas Javier, Gapp Chloé, Epelboin Yanouk, Figueras Ivern Pol, Barras Frédéric, Gendrin Mathilde
Microbiota of Insect Vectors Group, Institut Pasteur de la Guyane, Cayenne, French Guiana.
Viruses and RNA interference Unit, Institut Pasteur, Université Paris Cité, CNRS UMR3569, Paris, France.
Commun Biol. 2024 Dec 2;7(1):1603. doi: 10.1038/s42003-024-07319-7.
Mosquitoes rely on their microbiota for B vitamin synthesis. We previously found that Aedes aegypti third-instar larvae cleared of their microbiota were impaired in their development, notably due to a lack of folic acid (vitamin B9). In this study, we found that diet supplementation using a cocktail of seven B vitamins did not improve mosquito developmental success, but rather had a significant impact on the sex-ratio of the resulting adults, with an enrichment of female mosquitoes emerging from B vitamin-treated larvae. A transcriptomic analysis of male and female larvae identified some sex-specific regulated genes upon vitamin treatment. When treating germ-free larvae with individual B vitamins, we detected a specific toxic effect related to biotin (vitamin B7) exposure at high concentrations. We then provided germ-free larvae with varying biotin doses and showed that males are sensitive to biotin toxicity at a lower concentration than females. Gnotobiotic larvae exposed to controlled low bacterial counts or with bacteria characterised by slower growth, show a male-enriched adult population, suggesting that males require less bacteria-derived nutrients than females. These findings indicate that during larval development, mosquitoes have sex-specific nutritional requirements and toxicity thresholds, which impact the sex ratio of adults.
蚊子依靠其微生物群合成B族维生素。我们之前发现，清除了微生物群的埃及伊蚊三龄幼虫发育受损，特别是由于缺乏叶酸（维生素B9）。在本研究中，我们发现用七种B族维生素的混合物补充饮食并不能提高蚊子的发育成功率，反而对羽化出的成虫的性别比例有显著影响，用B族维生素处理过的幼虫羽化出的雌性蚊子增多。对雄性和雌性幼虫的转录组分析确定了维生素处理后一些性别特异性调控基因。在用单个B族维生素处理无菌幼虫时，我们检测到高浓度生物素（维生素B7）暴露会产生特定的毒性作用。然后我们给无菌幼虫提供不同剂量的生物素，并表明雄性比雌性对较低浓度的生物素毒性更敏感。暴露于受控低细菌数量或生长较慢细菌的无菌幼虫，羽化出的成虫群体中雄性居多，这表明雄性比雌性需要更少的细菌衍生营养物。这些发现表明，在幼虫发育过程中，蚊子有性别特异性的营养需求和毒性阈值，这会影响成虫的性别比例。
