Biology subjects

Orel, L.

Publications and source records attributed to Orel, L..

3 recordsLinked to original sources

bioRxiv2021

A Cryptochrome adopts distinct moon- and sunlight states and functions as moonlight interpreter in monthly oscillator entrainment

The moons monthly cycle synchronizes reproduction in countless marine organisms. The mass-spawning bristle worm Platynereis dumerilii uses an endogenous monthly oscillator to phase reproduction to specific days. Classical work showed that this oscillator is set by full moon. But how do organisms recognize such a specific moon phase? We uncover that the light receptor L-Cryptochrome (L-Cry) is able to discriminate between different moonlight durations, as well as between sun- and moonlight. Consistent with L-Crys function as light valence interpreter, its genetic loss leads to a faster re-entrainment under artificially strong nocturnal light. This suggests that L-Cry blocks "wrong" light from impacting on the monthly oscillator. A biochemical characterization of purified L-Cry protein, exposed to naturalistic sun- or moonlight, reveals the formation of distinct sun- and moonlight states characterized by different photoreduction- and recovery kinetics of L-Crys co-factor Flavin Adenine Dinucleotide. In vivo, L-Crys sun-versus moonlight states correlate with distinct sub-cellular localizations, indicating different signalling. In contrast, r-Opsin1, the most abundant ocular opsin, is not required for monthly oscillator entrainment. Our work reveals a new concept for correct moonlight interpretation involving a "valence interpreter" that provides entraining photoreceptor(s) with light source and moon phase information. These findings advance our mechanistic understanding of a fundamental biological phenomenon: moon-controlled monthly timing. Such level of understanding is also an essential prerequisite to tackle anthropogenic threats on marine ecology.

neuroscience↗

bioRxiv2021

Two light sensors decode moonlight versus sunlight to adjust a plastic circadian/circalunidian clock to moon phase

Many species synchronize their physiology and behavior to specific hours. It is commonly assumed that sunlight acts as the main entrainment signal for ~24h clocks. However, the moon provides similarly regular time information, and increasingly studies report correlations between diel behavior and lunidian cycles. Yet, mechanistic insight into the possible influences of the moon on ~24hr timers is scarce. We studied Platynereis dumerilii and uncover that the moon, besides its role in monthly timing, also schedules the exact hour of nocturnal swarming onset to the nights darkest times. Moonlight adjusts a plastic clock, exhibiting <24h (moonlit) or >24h (no moon) periodicity. Abundance, light sensitivity, and genetic requirement indicate Platynereis r-Opsin1 as receptor to determine moonrise, while the cryptochrome L-Cry is required to discriminate between moon- and sunlight valence. Comparative experiments in Drosophila suggest that Cryptochromes requirement for light valence interpretation is conserved. Its exact biochemical properties differ, however, between species with dissimilar timing ecology. Our work advances the molecular understanding of lunar impact on fundamental rhythmic processes, including those of marine mass spawners endangered by anthropogenic change.

neuroscience↗

bioRxiv2021

Analyses of cephalic and non-cephalic sensory cell types provide insight into joint photo- and mechanoreceptor evolution

Rhabdomeric Opsins (r-Opsins) are light-sensors in cephalic eye photoreceptors, but also function in additional sensory organs. This has prompted questions on the evolutionary relationship of these cell types, and if ancient r-Opsins cells were non-photosensory. Our profiling of cephalic and non-cephalic r-opsin1-expressing cells of the marine bristleworm Platynereis dumerilii reveals shared and distinct features. Non-cephalic cells possess a full set of phototransduction components, but also a mechanosensory signature. We determine that Pdu-r-Opsin1 is a Gq-coupled blue-light receptor. Profiling of cells from r-opsin1 mutants versus wild-types, and a comparison under different light conditions reveals that in the non-cephalic cells, light - mediated by r-Opsin1 - adjusts the expression level of a calcium transporter relevant for auditory mechanosensation in vertebrates. We establish a deep learning-based quantitative behavioral analysis for animal trunk movements, and identify a light-and r-Opsin-1-dependent fine-tuning of the worms undulatory movements in headless trunks, which are known to require mechanosensory feedback. Our results suggest an evolutionary concept in which r-Opsins act as ancient, light-dependent modulators of mechanosensation, and suggest that light-independent mechanosensory roles of r-Opsins likely evolved secondarily.

developmental biology↗