Research Progress in Area 3 方向 ( 三 ) 課題進展 159 Abstract Photosynthesis and chemosynthesis are two known processes on our planet to drive the primary production. Most organisms grow based on the carbon dioxide fixation through lightmediated photosynthesis process; while many animals thriving at dark deep-sea methane seeps live in a nutritional symbiosis with chemosynthetic bacteria that grow on chemical compounds, such as sulfide and methane, However, the molecular mechanisms of the host-symbiont relationship at cold seeps remain unclear. In this project, Prof. Qian’s team aims to provide a comprehensive information on the community structure of the chemosynthetic ecosystems in theWestern Pacific Ocean and Indian Ocean; to unveil the molecular mechanism of the symbiosis as a key adaptation to chemosynthetic ecosystem; and to study larval dispersal, connectivity, and migration pathways of shared megafaunal populations among different chemosynthetic ecosystems. Research Activities and Progress • Collected samples and conducted in situ experiments in two deep-sea cruises, one to Haima seep and another to the cold seep in Sagami Bay. • Analyzed the biological community structure of Haima seep, and the stable isotope within the species. • Studied symbiosis of dominant species, including Gigantopelta snails, Alviniconcha snails, Parascarpia tubeworms and Bathymodiolus mussels, by using omics tools. • Studied the population connectivity of Bathyacmaea limpets. Key Findings • Local habitat and geology cause uniqueness of biological community in Haima cold seep. • Gigantopelta snails harbours a much greater abundance of pattern recognition receptors, including toll-like receptors and lectins, enabling Gigantopelta snails to host two distinct endosymbionts. • Alviniconcha snail host immune system have different response to gill endosymbionts and intestine microbiome, indicating different symbiotic interaction. • Deep-sea limpets have diversified and connected under the complex interactions among local habitats, seafloor topography, and ocean currents. Research Output Publication 11 Trained personnel 16 Cold Seep Ecosystems in Northwest Pacific Prof. Pei-Yuan Qian The Hong Kong University of Science and Technology Fig 1. Genome landscape of the snail Gigantopelta aegis snails
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