Search for: All records

Abstract Marine organisms exhibit 12.4-hour rhythms of gene expression, physiology and behavior synchronized by tidal cues. The mechanism underlying these circatidal rhythms, and its overlap with the circadian clockwork, has remained elusive. However, recent studies showed that the core circadian gene BMAL1 sustains circatidal behavior in crustaceans. Therefore, we mutagenized the other three core circadian clock genes (PhCry2, PhPerandPhClk) inP. hawaiensis, a marine amphipod. We found that they are necessary for both circadian and circatidal behaviors. Moreover, all four core circadian genes are critical for 24-h oscillations of mRNA levels in circadian brain neurons and 12.4-h mRNA rhythms in circatidal neurons. Unexpectedly, the mutants indicate that PhCLK repressesPhPerexpression independently of PhBMAL1 specifically in circatidal neurons. Our study thus reveals that circadian and circatidal clocks share four core molecular components, but their transcriptional wiring differs. 

The coastline is a particularly challenging environment for its inhabitants. Not only do they have to cope with the solar day and the passing of seasons, but they must also deal with tides. In addition, many marine species track the phase of the moon, especially to coordinate reproduction. Marine animals show remarkable behavioral and physiological adaptability, using biological clocks to anticipate specific environmental cycles. Presently, we lack a basic understanding of the molecular mechanisms underlying circatidal and circalunar clocks. Recent advances in genome engineering and the development of genetically tractable marine model organisms are transforming how we study these timekeeping mechanisms and opening a novel era in marine chronobiology.