Microbiota 16s rRNA genotyping in S. typhle eggs and broodpouch

While originally acquired from the environment, a fraction of the microbiota is transferred from parents to offspring. The immune system shapes the microbial colonization, while commensal microbes may boost host immune defences. Parental transfer of microbes in viviparous animals remains ambiguous, as the two transfer routes (transovarial vs. pregnancy) are intermingled within the maternal body. Pipefishes and seahorses (Syngnathids) are ideally suited to disentangle transovarial microbial transfer from a contribution during pregnancy due to their maternal egg production and their unique male pregnancy. We assessed the persistency and the changes in the microbial communities of the maternal and paternal reproductive tracts over proceeding male pregnancy by sequencing microbial 16S rRNA genes of swabs from maternal gonads and brood pouches of non-pregnant and pregnant fathers. Applying parental immunological activation with heat-killed bacteria, we evaluated the impact of parental immunological status on microbial development. Our data indicate that maternal gonads and paternal brood pouches harbor distinct microbial communities, which could affect embryonal development in a sex-specific manner. Upon activation of the immune system, a shift of the microbial community was observed. The activation of the immune system induced the expansion of microbiota richness during late pregnancy, which corresponds to the time point of larval mouth opening, when initial microbial colonization must take place.尽管微生物群（microbiota）最初从环境中获取，但其中一部分会由亲本传递给子代。免疫系统可调控微生物的定殖过程，而共生微生物（commensal microbes）则能够增强宿主的免疫防御能力。胎生动物（viviparous animals）的微生物亲本传递机制仍不明确，因为两种传递途径（经卵传递（transovarial）与孕期传递）在母体内相互交织。海龙（pipefishes）与海马（seahorses）隶属于海龙科（Syngnathids），由于其雌性产卵且具备独特的雄性妊娠特性，是区分经卵传递微生物与孕期传递微生物贡献的理想研究对象。 本研究通过对未妊娠雌性的性腺拭子以及妊娠与未妊娠雄性育幼囊（brood pouches）拭子的微生物16S rRNA基因进行测序，分析了雄性妊娠进程中雌雄生殖道微生物群的持久性与动态变化。本研究采用灭活细菌（heat-killed bacteria）激活亲本的免疫系统，以此评估亲本免疫状态对微生物群发育的影响。研究数据显示，雌性性腺与雄性育幼囊内的微生物群结构存在显著差异，且可能以性别特异性的方式影响胚胎发育（embryonal development）。当免疫系统被激活后，微生物群结构发生了显著偏移。免疫系统激活可在妊娠晚期促进微生物群丰富度的提升，而这一时期恰好对应幼鱼开口期（larval mouth opening）——此时正是初始微生物定殖的关键阶段。