基于肠道菌群-宿主共代谢研究三疣梭子蟹响应海洋酸化的机理

Increased anthropogenic CO2 emissions accelerates the ocean acidification (OA). As decapod crustaceans, crabs are thought to be particularly vulnerable to OA. There is a need to unravel the physiological mechanism of crabs responding to OA. Gut microbiomes play a central role in nutrition and immunity in animals. Whether are they important for the response of crabs to OA? Our hypothesis is that OA stress leads to the alteration of gut microbial composition, consequently resulting in the cascading effects including changes in the co-metabolism between gut microbes and host, changes in the gut digestive and immune function, and changes in the crab phenotype. In this proposed research, we will combine advanced molecular technologies such as high throughput sequencing, nuclear magnetic resonance (NMR)- and gas chromatography-mass spectrometer (GC-MS)-based metabolomics, and real-time quantitative PCR (RT-qPCR) as well as immune and enzymatic methods to investigate the dynamic changes of function and structure of gut microbiota, metabolite compositions of intestine and its microbiomes, and activities of immune related genes and enzymes of intestine during the response of Portunus trituberculatus to OA stress. Furthermore, we will use multivariate data analysis and multivariable correlation analysis to reveal the interaction between gut microbiota and crab host and its function implicated in crab response to OA. The results of this study will provide theoretical foundation for unraveling the effects of OA on the crustaceans.

人类活动导致海洋水体的快速酸化，蟹类作为钙化动物，对海洋酸化尤其敏感。解明蟹类对海洋酸化的响应机制是应对海洋酸化的前提。肠道菌群在动物的营养和免疫中发挥着中心地位作用，它在蟹类响应海洋酸化的过程中是否也具有重要作用？我们的假设是：蟹类受到海洋酸化胁迫后，其肠道菌群结构改变，导致其与肠道的共代谢改变，进而影响肠道的消化和免疫功能，最终影响蟹类表型。本项目拟以三疣梭子蟹为研究对象，通过人工模拟海洋酸化环境，采用高通量测序、核磁共振和气相色谱质谱相结合的组合代谢组学、实时定量PCR等分子技术，并结合免疫学和酶学方法，分析肠道菌群结构和功能、代谢物组成以及免疫相关基因和酶表达活性等变化，揭示海洋酸化对梭子蟹肠道及菌群的影响；再借助多变量统计分析和多元相关分析，明确肠道菌群与宿主的互作关系，阐明肠道菌群在梭子蟹响应海洋酸化中的作用。本项目研究成果可为揭示海洋酸化对甲壳类动物的影响提供重要的理论依据。

探究三疣梭子蟹对海洋酸化（OA）的响应对于了解该具有商业意义的中国蟹类物种的未来发展至关重要。近来的研究报道了OA对甲壳类动物的负面影响。本项目对三疣梭子蟹进行了为期4周的CO2胁迫（当前：380 μatm；2100年：750 μatm；2200年：1500 μatm），分析了OA对梭子蟹的存活、生长、消化、抗氧化能力、免疫功能、组织代谢物和肠道细菌以及海水细菌的影响，并分析了OA对海水水质和海水微生物碳氮磷硫生物地球化学循环相关基因的影响。结果表明，OA能增强梭子蟹的存活率，但显著延滞了其生长。生长的延滞与梭子蟹肠道、肌肉和肝胰腺代谢物的变化呈显著正相关，而存活率的提高与碳酸盐系统、海水细菌和肠道细菌的变化以及抗氧化和消化酶的活性显著相关。其中，碳酸盐体系通过降低水体中的活性氨浓度促进梭子蟹的存活，还通过改变水体细菌的多样性、群落组成和相互作用关系，改变水体细菌的碳氮磷硫代谢潜力，进而改变水体的水质指标，最终促进了梭子蟹的存活。总之，本项目研究表明OA可导致水体水质、梭子蟹抗氧化能力，免疫功能、代谢物和肠道菌群发生改变，也可导致海水细菌的菌群及其代谢功能潜力的显著改变，从而影响梭子蟹的存活和生长。