CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Center for Ocean Mega-Science, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao, 266071, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Center for Ocean Mega-Science, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao, 266071, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, 1 Wenhai Road, Qingdao, 266000, China.
Fish Shellfish Immunol. 2019 Mar;86:246-252. doi: 10.1016/j.fsi.2018.11.041. Epub 2018 Nov 17.
Deep-sea Bathymodiolus mussels depend on the organic carbon supplied by symbionts inside their gills. In this study, optimized methods of quantitative real-time PCR and fluorescence in situ hybridization targeted to both mRNA and 16S rRNA were used to investigate the gill symbionts of the cold-seep mussel Bathymodiolus platifrons, including species composition, environmental dependency and immune control by the host. Our results showed that methanotrophs were the major symbiotic bacteria in the gills of B. platifrons, while thiotrophs were scarce. In the mussels freshly collected from the deep sea, methanotrophs were housed in bacteriocytes in a unique circular pattern, and a lysosome-related gene (VAMP) encoding a vesicle-associated membrane protein was expressed at a high level and presented exactly where the methanotrophs occurred. After the mussels were reared for three months in aquaria without methane supply, the abundance of methanotrophs decreased significantly and their circle-shaped distribution pattern disappeared; in addition, the expression of VAMP decreased significantly. These results suggest that the symbiosis between B. platifrons and methanotrophs is influenced by the environment and that the lysosomal system plays an important immune role in controlling the abundance of endosymbionts in host. This study provides a reliable method for investigating symbionts in deep-sea mussels and enriches the knowledge about symbionts in B. platifrons.
深海贻贝依赖于其鳃内共生体提供的有机碳。在这项研究中，使用了优化的定量实时 PCR 和荧光原位杂交方法，针对 mRNA 和 16S rRNA，研究了冷渗贻贝 Bathymodiolus platifrons 的鳃共生体，包括物种组成、环境依赖性和宿主的免疫控制。我们的结果表明，甲烷营养菌是 B. platifrons 鳃中的主要共生细菌，而硫营养菌则很少。在刚从深海采集的贻贝中，甲烷营养菌被安置在细菌细胞中，呈独特的圆形模式，溶酶体相关基因 (VAMP) 编码囊泡相关膜蛋白，其表达水平很高，并且正好出现在甲烷营养菌所在的位置。在贻贝在没有甲烷供应的水族箱中饲养三个月后，甲烷营养菌的丰度显著下降，其圆形分布模式消失；此外，VAMP 的表达也显著下降。这些结果表明，B. platifrons 和甲烷营养菌之间的共生关系受到环境的影响，溶酶体系统在控制宿主内共生体的丰度方面发挥着重要的免疫作用。本研究为研究深海贻贝中的共生体提供了可靠的方法，并丰富了关于 B. platifrons 共生体的知识。
