JpGU-AGU Joint Meeting 2017

Presentation information

[EJ] Oral

B (Biogeosciences) » B-PT Paleontology

[B-PT04] [EJ] Evolution of Chemosynthetic Ecosystem in Earth History

Sun. May 21, 2017 9:00 AM - 10:30 AM 106 (International Conference Hall 1F)

convener:Robert Jenkins(School of Natural System, College of Science and Engineering, Kanazawa University), Hiromi Kayama WATANABE(Japan Agency for Marine-Earth Science and Technology), Takami Nobuhara(Science Education (Geology), Faculty of Education, Shizuoka University), Ryuichi Majima(Faculty of Education and Human Sciences, Yokohama National University), Chairperson:Robert Jenkins(School of Natural System, College of Science and Engineering, Kanazawa University), Chairperson:Hiromi Watanabe(JAMSTEC)

9:45 AM - 10:00 AM

[BPT04-04] Mussel genomes provide insights into adaptation to deep-sea chemosynthetic environments

★Invited papers

*Pei-Yuan Qian1, Jin Sun1, Jian-Wen Qiu2 (1.Hong Kong University of Science and Technology, 2.Hong Kong Baptist University)

Keywords:Genome sequencing, Bathymodiolus, Symbiosis

The environment of deep-sea hydrothermal vents and methane seeps is characterised by darkness, lack of photosynthesis-derived nutrients, high hydrostatic pressure, variable temperatures and high concentrations of heavy metals and other toxic substances. Despite this, these ecosystems support dense populations of specialised macrobenthos such as giant tubeworms, mussels, limpets, clams and shrimps. Lack of genome information hinders understanding of the adaptation of these animals to such inhospitable environment. Here we report the genomes of a deep-sea vent/seep mussel Bathymodiolus platifrons Hashimoto & Okutani, 1994 and a shallow-water mussel Modiolus philippinarum (Hanley, 1843). Phylogenetic analysis shows that these mussel species diverged approximately 110.4 million years ago (MYA). Many gene families, especially those for stabilising protein structures and removing toxic substances from the cell, are greatly expanded in B. platifrons, indicating adaptation to extreme environmental conditions. The B. platifrons innate immune system is considerably more complex than that of other lophotrochozoan species including M. philippinarum, with significant expansion and high expression of gene families related to immune recognition, endocytosis and caspase-mediated apoptosis in the gill, revealing presumed genetic adaptation of the deep-sea mussel to the presence of its chemoautotrophic endosymbionts. A follow-up metaproteomic analysis of the gill of B. platifrons found methanotrophy, assimilatory sulfate reduction, and ammonia metabolic pathways in the symbiont, providing energy and nutrients to allow the host to thrive without dependent on photosynthesis derived food. Our study of the genomic composition allowing symbiosis in extremophile molluscs gives wider insights into the mechanisms of symbiosis in other organisms such as deep-sea tubeworms and shallow-water corals.
In addition, we would also like to take this opportunity to introduce a large-scale program on “U-Shape” area that targets at the vents along the Mid-Ocean Ridge of both South Atlantic and Western Indian Ocean, to be launched by China Ocean Mineral Resource Research and Development Association, for which we call for international collaboration in next 15 years.