黄鳍鲷肠道菌群对dmrt1基因调控影响机制研究

Gut microbiota, which can affect the growth and development of the host, is one of the most important symbiotic microbiotas. It’s of vital importance to investigate the interaction between the structure and function of gut microbiota and sex. Even though it has been proved that gut microbiota can affect hormone secretion level, few studies focused on the sexual regulation mechanism of gut microbiota. Protandrous yellowfin seabream (Acanthopagrus latus) can show male and female characteristics sequentially without changing genetic background. Sex-relating key gene dmrt1 can retain the function of testis and suppress the development of ovary. Preliminary results have proved that the composition of gut microbiota changed as the mature male fish went into sex reversal process. Meanwhile, dmrt1 showed differentially expression, which supports further exploration of regulating sex reversal process via gut microbiota is feasible. This research will build various gut microbiota in male yellowfin seabream, aiming to elucidate the regulation mechanism of dmrt1 gene expression through gut microbiota, with quantification of important HPG (hypothalamic-pituitary-gonadal) axis relevant gene expression, morphological observation of gonadal tissue, as well as secretion level detection of sexual hormone, as indirect evidences. The research can shed light on the dynamic change and internal connection between gut microbiota and dmrt1 gene expression in yellowfin seabream, which will offer implications about artificially regulating sex ratios through microbiological ways and has both scientific theoretical and aquaculture practical significance.

肠道菌群是鱼类最重要的共生菌群之一，与宿主生长发育密切相关。肠道菌群的结构功能与性别之间的相互影响备受关注。虽然已发现肠道菌群影响性激素水平，但是菌群对性别调控影响机制的研究甚少。黄鳍鲷（Acanthopagrus latus）性别决定系统属于雌雄同体、雄性先熟类型。dmrt1基因能够维持精巢功能、抑制卵巢发育，是黄鳍鲷性别相关关键基因。前期研究结果证实，黄鳍鲷在性逆转过程中其体内肠道菌群组分差异显著，同时dmrt1基因表达显著下调。本研究拟以全同胞家系黄鳍鲷雄鱼为实验对象，使用菌群移植方法构建不同肠道菌群，研究菌群对dmrt1基因表达的调控影响机制，并以重要下丘脑-垂体-性腺（HPG）轴相关基因定量检测、性腺组织形态观察、性激素水平测定为间接证据，揭示黄鳍鲷的肠道菌群与dmrt1基因表达变化之间的内在联系，为通过微生物学手段调节性别比例提供重要理论依据，对科学理论和水产实践具有重要意义。

肠道菌群是鱼类最重要的共生菌群之一，其结构功能与性别之间的相互影响备受关注。黄鳍鲷（Acanthopagrus latus）性别决定系统属于雌雄同体、雄性先熟类型。本项目以全同胞家系黄鳍鲷雄鱼为实验对象，使用菌群移植方法构建了具有不同肠道菌群的黄鳍鲷个体。通过分析自然条件下不同性别阶段黄鳍鲷和菌群移植后黄鳍鲷肠道菌群结构特征，结合性别相关基因定量检测、性腺组织形态观察、性激素水平测定，揭示黄鳍鲷的肠道菌群与dmrt1基因表达变化之间的内在联系。本研究主要结果包括：（1）建立黄鳍鲷菌群移植方法，可有效将不同性别阶段黄鳍鲷肠道菌群定植至受体中；（2）黄鳍鲷肠道菌群多样性和组成都具有显著的性别差异；（3）精巢发育相关基因cyp11a、cyp17a、piwil1、dmrt1、amh、sox9a在雄鱼中的表达水平显著高于雌性，卵巢发育相关基因cyp19a1a、hsd17b1、figla、zp3、foxl2、sox3在雌鱼中的表达水平显著高于雄性；（4）移植雌性肠道菌群个体的性腺组织形态和血清性激素水平等都表现出雌鱼特征；（5）相关性分析筛选出与性激素水平和性别相关基因表达水平具有显著相关关系的菌属，可作为候选微生物标志物用于进一步探究和验证。本研究可为通过微生物学手段调节性别比例提供重要理论依据，对科学理论和水产实践具有重要意义。