Abstract

Shedding light on lunar rhythms

Since the dawn of life the marine ecosystem is governed by a multitude of environmental cycles. In accordance with these cycles, many marine species synchronize their time of reproduction with the photoperiod, the lunar cycle and to a specific time of the day. Yet, despite the fundamental nature of these light-controlled ‘marine’ rhythms, we have very only a limited knowledge about their molecular basis. The reproductive cycles of the annelid Platynereis dumerilii are synchronized by the interplay of a circadian and a circalunar clock, which in nature are synchronized by sunlight and moonlight, respectively. We have started to dissect the molecular mechanisms that govern light-dependent circadian and circalunar rhythmicity in the marine annelid Platynereis dumerilii. Our analysis covers three areas: (i) the measurement of light spectra and intensities that the animals receive in their natural environments over the lunar cycle. (ii) the characterization of candidate lunar light sensors and their spectral sensitivity (iii) the analysis of circadian clock components and their regulation under light regimes that mimic different phases of the lunar cycle. Our results suggest that lunar and circadian clocks are molecularly independent, but interconnected, and provide new molecular entry points into the study of light-dependent marine rhythms and their evolution.