Periodic Reporting for period 2 - Mari.Time (Dissecting the mechanistic basis of moon-controlled monthly timing mechanisms in marine environments)
Okres sprawozdawczy: 2021-07-01 do 2022-12-31
The correct timing of biological processes is crucial for organisms. However, while sun(light)-dependent timing processes have been studied in great detail, moonlight has been largely neglected for its role on animal physiology and behavior. However, any organism that uses light as a synchronization cue for its inner oscillators faces the challenge to discriminate between sun- and moonlight. In many species moonlight (and even specific moon phases) could impact on the endogenous oscillators. This is the case for the nocturnal, marine mass spawning bristle worm Platynereis dumerilii, for both its monthly and daily inner oscillators. Other species, like the more day-active fruit fly Drosophila melanogaster, need to prevent moonlight from shifting their endogenous circadian clock under naturalistic conditions. Under natural conditions, organisms thus need to discriminate between the type of light (sun or moon) that reaches them, because it has different ecological meanings.
Our overall objectives are to understand the molecular mechanisms how organisms, especially our main model system Platynereis dumerilii, can use light to entrain their different oscillators. How can different worms entrain to the right moon phase? We also aim to better understand the molecular and cellular nature of the oscillatory mechanisms and how the signal is conveyed to control reproductive physiology and behavior. Last, but not least, while lab experiments are useful as they provide relatively stable and controllable conditions, the lab environment is very different from the natural environment organisms evolved in. This is particularly relevant in the context of natural light. Thus, we also aim to test mutant and wildtype Platynereis worms under natural (especially light) conditions.
Understanding the impact of natural light on animals is of high ecological and environmental, as well as potentially medical relevance. Marine mass spawners, such as Platynereis, but also corals and various other marine animals and non-animals are critical for ecologically stable ecosystems in the oceans. In times of climate change and abundant artificial light it is crucial to understand the mechanisms that underly their timing, because this will allow to estimate the effects on them and to provide guided measures for their protection. A healthy and stable ocean ecology is essential for the stability of the earth’s climate.
Our overall objectives are to understand the molecular mechanisms how organisms, especially our main model system Platynereis dumerilii, can use light to entrain their different oscillators. How can different worms entrain to the right moon phase? We also aim to better understand the molecular and cellular nature of the oscillatory mechanisms and how the signal is conveyed to control reproductive physiology and behavior. Last, but not least, while lab experiments are useful as they provide relatively stable and controllable conditions, the lab environment is very different from the natural environment organisms evolved in. This is particularly relevant in the context of natural light. Thus, we also aim to test mutant and wildtype Platynereis worms under natural (especially light) conditions.
Understanding the impact of natural light on animals is of high ecological and environmental, as well as potentially medical relevance. Marine mass spawners, such as Platynereis, but also corals and various other marine animals and non-animals are critical for ecologically stable ecosystems in the oceans. In times of climate change and abundant artificial light it is crucial to understand the mechanisms that underly their timing, because this will allow to estimate the effects on them and to provide guided measures for their protection. A healthy and stable ocean ecology is essential for the stability of the earth’s climate.
In our work we now uncovered how the discrimination between sun- and moonlight and even moon phase can be achieved by the cryptochrome protein L-Cry in Platynereis dumerilii. We unraveled that depending on the type of light the protein can assume distinct biochemical states that also correlate with distinct subcellular localizations, where it subsequently controls the impact of light on its monthly and plastic circadian/circalunidian oscillators. We also showed that an Opsin (r-Opsin1), prominently expressed in the worm’s eyes, is functionally required to mediate lunar light responses on its plastic circadian/circalunidian, but not monthly oscillator. In contrast, the combinatorial signaling of dCry and Opsins prevents moonlight to strongly impact on the ~24hr oscillator of the day-active fruit fly. We have also started to further investigate several putative interactors and downstream targets of Platynereis L-Cry.
In parallel, we successfully constructed outside tank systems, that allow the natural light to pass through without alterations. We used these tanks to sample wildtype and mutant worms and are currently in the process to prepare them for in-depth transcriptomic and proteomic analyses in comparison to samples of the same strains taken in the laboratory. This should allow us to obtain a deeper understanding of the mechanisms of sun- versus moonlight under natural illumination conditions.
In parallel, we successfully constructed outside tank systems, that allow the natural light to pass through without alterations. We used these tanks to sample wildtype and mutant worms and are currently in the process to prepare them for in-depth transcriptomic and proteomic analyses in comparison to samples of the same strains taken in the laboratory. This should allow us to obtain a deeper understanding of the mechanisms of sun- versus moonlight under natural illumination conditions.
Our result on the mechanisms of sun-/ moonlight discrimination are clearly beyond the state of the art as they for the first time also provide a mechanistic (on biochemical, cell biological and genetic level) explanation how organisms can synchronize to a specific moon phase. We also provide evolutionary insight in a comparison between a night active and a day active animal that presents a clear scientific advancement.
With further progression of the project we expect to gain insight into the differences between lab and field experiments, by this obtaining a better understanding how the system has adapted to its true environmental (light) conditions and to test for potential artifacts that could arise from the artificial lab conditions. We also expect to obtain more detailed molecular insight how L-Cry conveys its signals to the circalunar oscillator and how the oscillator conveys the time information further to the gonads and nervous system.
With further progression of the project we expect to gain insight into the differences between lab and field experiments, by this obtaining a better understanding how the system has adapted to its true environmental (light) conditions and to test for potential artifacts that could arise from the artificial lab conditions. We also expect to obtain more detailed molecular insight how L-Cry conveys its signals to the circalunar oscillator and how the oscillator conveys the time information further to the gonads and nervous system.