Collaborative Research: Molecular and neural mechanisms controlling circatidal rhythms in Parhyale hawaiensis

All organisms are deeply impacted by environmental cycles caused by the movement of the Earth and the Moon in space. To predict them, they use biological timers that track the progression of these cycles. We humans are particularly familiar with the circadian clock, which optimize our physiology and behavior with the time of day. However, marine life is also deeply impacted by tides, from the coastline to the deep corners of the ocean. Indeed, tides impact not just sea levels, but also water temperature, currents and food availability. To anticipate and adapt to tides, marine animals carry an internal ~12.4-hour timekeeper called the circatidal clock. Unlike the circadian clock, the circatidal clock is poorly understood. The PIs have established the small crustacean P. hawaiensis as a potent model to understand how the circatidal clock works, and how it optimizes behavioral activity during the tidal cycle. The goal is to use the genetic tools available in P. hawaiensis to identify the genes that encode the circatidal clock and characterize the neurons that use them to optimize behavior with tides. Comparing the circadian and circatidal clocks, and defining how these two pacemakers interact to control behavior will result in a better understanding of how animals remain resilient in an ever-changing environment. The PIs will also organize a yearly scientific symposium that will bring together scientists from UMass Chan Medical School, the Marine Biological Laboratory in Woods Hole, and the University or Puerto Rico to foster exciting scientific exchanges and collaborations between these three institutions. This project advances NSF’s priorities in Biotechnology. In the oceans, and particularly on the coastline, animals face a remarkably complex, rhythmic environment. In addition to being subjected to solar and seasonal cycles, they must also cope with tides, which can completely transform their environment every 12.4 hours. Thus, marine animals carry not only a circadian clock to track the solar day, but also a circatidal clock to anticipate tides. A great deal about the circadian clock is known, but our understanding of circatidal clocks has lagged due to the absence of a suitable model organism with robust genetics. The team has recently introduced P. hawaiensis as the first genetically tractable model to study circatidal clocks and their goal is to elucidate the molecular and neural mechanisms used to anticipate circatidal rhythms by exploiting the powerful transgenic and genome-editing tools available in P. hawaiensis. They aim to identify the core circatidal clock genes and understand how the circadian and circatidal clocks differ to generate molecular and behavioral rhythms of very different periods (24 h vs 12.4h). The PIs also aim to characterize the neurons in which core circadian and circatidal clock genes are expressed to understand the different environmental inputs that entrain them, and how they interact to optimize behavioral activity in response to both the solar and tidal cycles. This work will considerably extend our understanding of biological rhythms, which are critical for the health and survival of most organisms on Earth. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.