深海偏顶蛤发育过程中含菌上皮组织的显微结构变化及分子调控机制

深海偏顶蛤是深海化能生态系统的广布种和优势种，与化能细菌的稳定共生关系对深海“黑暗食物网”的稳态维持至关重要。因缺少对深海偏顶蛤共生体系动态互作过程的认知，所以难以解析共生体系稳定维持的机制。由此，本项目以南海F冷泉平端深海偏顶蛤(Gigantidas platifrons)的稚贝期为切入点，聚焦其稚贝阶段存在共生菌由全身上皮组织感染到鳃上皮组织感染的动态变化过程，采取亚细胞尺度的三维重构技术与高空间分辨率的转录组技术，揭示G. platifrons非鳃(外套膜和足)上皮组织中共生菌丢失前后的细胞亚显微变化和基因调控网络差异，推测非鳃上皮中共生菌丢失的原因。同时，根据稚贝生长过程中非鳃上皮组织和鳃上皮组织的结构及基因表达模式差异，进而剖析鳃上皮组织可以持续维持共生状态的原因。本项目的实施将拓展深海偏顶蛤化能共生体系的认知，为深海生物极端环境适应性提供数据支撑和理论依据。

Deep-sea mussels are dominant species in the deep-sea chemosynthesis ecosystem worldwide. The stable symbiosis relationship between the chemosynthetic bacteria and the mussel has strengthen their nutrition linkages and facilitate the energy transport in the deep-sea. Thus, the interaction plays important roles on the homeostasis of dark food web. However, due to the lack of knowledges on dynamic cross-talking of the symbionts and the mussel, it is difficult to understand the maintenance mechanism of the symbiosis system. The mussels interact with the bacteria extensively during their juvenile period, providing us a good model to study the symbiosis. Therefore, this project focused the ultramicroscopic and gene expression profiles of the juvenile of Gigantidas platifrons from the cold seep (F site) to reveal the special-specialized mechanism of the symbionts in the G. platifrons. Serious-TEM 3d reconstruction and high-resolution spatial transcriptome sequencing were applied in the project. The reason for the loss of symbiotic bacteria in non-gill (mantle and foot) epithelial tissues would be analyzed from tissue structural changes and gene expression regulation. Simultaneously, the reasons why gill epithelial tissue can continue to maintain a symbiotic state could be further interpreted by comparing the differences in the structure and gene expression patterns of bacteriocyte from non-gill epithelial tissues and gill epithelial tissue during the growth of juveniles. The implementation of this project will expand the understanding of the deep-sea mussel chemosynthesis, and provide insights into the extreme environmental adaptation of the deep-sea mussels.