Circatidal control of gene expression in the deep-sea hot vent shrimpRimicaris leurokolos

Abstract

Biological clocks are a ubiquitous feature of all life, enabling the use of natural environmental cycles to track time. Although studies on circadian rhythms have contributed greatly to the knowledge of chronobiology, biological rhythms in dark biospheres such as the deep sea remain poorly understood. Despite a lack of day-night cycles, the deep sea is still affected by the tide, and some recent evidences suggest that the tidal cycle likely has non-negligible temporal effects on deep-sea organisms. Here, based on a free-running experiment, we reveal potentially endogenous biological rhythms in the gene expression of the deep-sea hydrothermal vent shrimp Shinkaicaris leurokolos. Oscillations with ~12-hour periods, likely reflecting tidal influence, greatly prevail over others in the temporal transcriptome. The tidal oscillated rhythms exhibit an antiphased expression pattern divided into two internally synchronized clusters, correlated with wide-ranging biological processes in the nucleus and cytoplasm, respectively. In some cases, circadian clock genes are necessary for circatidal rhythms and can be adjusted to tidal frequency. However, almost none of the identified S. leurokolos circadian clock genes show obvious rhythmicity, likely indicating an independent circatidal clock. These findings provide new insights into the temporal adaptations in deep-sea organisms and suggest that deep-sea hydrothermal vent organisms may be intriguing models for chronobiological studies.