Biological rhythms in the deep-sea hydrothermal mussel Bathymodiolus azoricus
Audrey M. Mat, Jozée Sarrazin, Gabriel V. Markov, Vincent Apremont, Christine Dubreuil, Camille Eché, Caroline Fabioux, Christophe Klopp, Pierre‐Marie Sarradin, Arnaud Tanguy, Arnaud Huvet, Marjolaine Matabos
Abstract
Biological rhythms are a fundamental property of life. The deep ocean covers 66% of our planet surface and is one of the largest biomes. The deep sea has long been considered as an arrhythmic environment because sunlight is totally absent below 1,000 m depth. In the present study, we have sequenced the temporal transcriptomes of a deep-sea species, the ecosystem-structuring vent mussel Bathymodiolus azoricus. We reveal that tidal cycles predominate in the transcriptome and physiology of mussels fixed directly at hydrothermal vents at 1,688 m depth at the Mid-Atlantic Ridge, whereas daily cycles prevail in mussels sampled after laboratory acclimation. We identify B. azoricus canonical circadian clock genes, and show that oscillations observed in deep-sea mussels could be either a direct response to environmental stimulus, or be driven endogenously by one or more biological clocks. This work generates in situ insights into temporal organisation in a deep-sea organism.