The research, published in Current Biology, presents an exciting new perspective on how organisms define biological time. It reveals a body-clock driving tidal rhythms that follows the 12.4 hour cycle of the tide.
This is independent of the 24 hour body clock (the circadian cycle) shared by other animals and plants, including humans, which results in jet-lag when out of kilter with the day/night cycle of a new destination.
Eurydice pulchra. Image: Michael Hasting
The paper, Dissociation of Circadian and Circatidal Timekeeping in the Marine Crustacean Eurydice pulchra, follows nearly ten years of research by Leicester geneticists, along with colleagues at the Universities of Bangor, the BBSRC-funded Institute of Biological, Environmental and Rural Sciences at Aberystwyth University, and the MRC Laboratory of Molecular Biology in Cambridge.
They made the discovery by “turning off” Eurydice’s circadian clock by genetically knocking down two of the key circadian clock genes, which they had identified.
They were also able to block the circadian cycle by exposing Eurydice to a constant bright light for many days.
With these genetic and environmental manipulations, the circadian rhythm became severely disrupted, but the tidal swimming rhythm kept on ticking every 12.4 hours.
This showed that the animals’ tidal patterns are independent of their 24 hour circadian clock.
The project was funded by grants from the Biotechnology and Biological Sciences Research Council (BBSRC), as well as funding from the Medical Research Council.
Dr David Wilcockson at Aberystwyth University said: “We know that we have special timing cells deep in our brains that keep us to a tight 24 hour schedule, even when we are removed from the natural environment, such as in sub mariners. This is extremely important to our well-being and we know that faulty clocks in humans may lead to serious medical conditions ranging from cancer to mental health disorders.”
“The discovery of the circadian clock mechanisms in various terrestrial species from fungi to humans was a major breakthrough for biology. The identification of the tidal clock as a separate mechanism now presents us with an exciting new perspective on how organisms define biological time.”
The team have now secured a new four-year grant from BBSRC to sequence the Eurydice pulchra genome.
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