夏眠期间刺参肠道菌群结构、功能及与宿主互作特征研究

Apostichopus japonicus is an important economic species in China, aquaculture development has been heavily influenced by the deterioration of aquacultural environment as well as high frequency of diseases, and aestivation is a high rate of disease stage. Research indicates that gut microbiota is playing a critical role in metabolic regulation and immune remodeling in dormant animals. Hence it is profoundly theoretic and practically significant to study the mutual regulation between sea cucumber and its gut bacteria during aestivation. In this project, we will reveal the composition shift and biological function of gut microbiota in A. japonicus during each aestivation stage, will screen out the core aestivation microbiome and key differentially expressed genes, will analyze the host intestinal mucosal physiologic , functional and metabolite response characteristics, and will explore the interaction characteristics of gut microbiota and host during aestivation by using high-throughput sequencing of 16S rRNA amplicons and metatranscriptome. The results are significant to mine the potential function of sea cucumber gut microbiota, to enrich the intestinal microecology of marine invertebrates and to provide basic theoretical reference for the optimal community structure of gut microbiota and healthy aquaculture in sea cucumbers.

刺参是我国海水养殖的重要经济物种，但养殖环境恶化导致的病害问题严重制约了产业发展，探索刺参与肠道菌群的互作调控有望成为解决这一问题的关键。夏眠是刺参应对高温环境的重要生存策略，肠道菌群在刺参夏眠代谢重组和免疫重塑中很可能发挥了重要作用，因此夏眠可视为探索自然状态下刺参肠道菌群与宿主互作的良好模型。本项目采用基于高通量测序平台的16SrRNA扩增子测序和宏转录组技术，揭示夏眠不同时期刺参肠道菌群的群落组成结构和基因功能的动态变化，筛选刺参肠道菌群的核心群系和关键差异表达基因；结合宿主肠道结构、功能及菌群代谢物的响应特征，挖掘肠道共生微生物在夏眠中与宿主互作特征，探讨夏眠背景下刺参与肠道菌群的共生关系。项目的开展对挖掘刺参肠道共生微生物群落功能具有重要意义，有助于丰富海洋无脊椎动物肠道微生态学，并为优化刺参肠道微生物群落结构和刺参绿色健康养殖提供理论参考。

夏眠是刺参应对高温环境的重要生存策略，肠道菌群在刺参夏眠代谢重组和免疫重塑中很可能发挥了重要作用，因此夏眠可视为探索自然状态下刺参肠道菌群与宿主互作的良好模型。本项目基于高通量测序平台的16SrRNA扩增子测序技术查明了夏眠不同阶段刺参肠道共生菌群的种群组成、物种多样性、群落结构变化特征，结果表明夏眠刺参肠道菌物种丰富度和多样性最低并伴随物种丰度变化：依赖外源营养细菌丰度下降而可分解宿主内源营养的细菌丰度升高；利用宏基因组测序技术查明了刺参夏眠不同阶段肠道菌群功能基因的组成、注释信息库功能基因的丰度差异并筛选了不同夏眠阶段组间具有统计学差异的功能基因。组织切片结果表明夏眠阶段的刺参肠道萎缩退化严重，尤其体现在粘膜层并伴随着可分泌酸性黏蛋白Ⅱ型黏液细胞增多。同时夏眠刺参表现出明显的消化酶和抗氧化防御酶活力下降，但蛋白类消化酶（胃蛋白酶和胰蛋白酶）活性升高。此外，进一步的酶活和基因表达研究表明夏眠期间刺参免疫防御反应加强。基于超高效液相色谱-电喷雾电离飞行时间质谱(UPLC-ESI-Q-TOF/MS)代谢组技术对不同夏眠阶段的刺参肠道内容物进行分析，共鉴定获得了424个代谢产物，并筛选了不同夏眠对比组的差异代谢产物。结果表明刺参在夏眠期间倾向于抑制糖类代谢、促进脂质代谢来满足能量供应，并以增加非酶类抗氧化分子这种高效节能的策略应对氧化应激反应。进一步的相关分析则表明部分代谢物与肠道菌群存在显著的相关关系，表明肠道菌群很可能参与了宿主的代谢调控过程。项目的实施探讨了夏眠背景下刺参与肠道菌群的共生关系，对挖掘刺参肠道共生微生物群落功能具有重要意义，有助于丰富海洋无脊椎动物肠道微生态学，并为优化刺参肠道微生物群落结构和刺参绿色健康养殖提供理论参考。

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