Two new studies, performed by one team using the sea louse Eurydice pulchra (an intertidal crustacean known to alter its swimming behavior with the tidal cycle) and by another using the marine annelid Platynereis dumerilii (aka the bristle worm, noted for its spawning sessions under the new moon), explore the mechanisms behind tidal rhythms.
For the sea louse, the researchers began by abolishing all of the animal’s rhythms by keeping the animals’ test tubes in total darkness for more than a month. They then began vibrating the tubes at regular intervals, replicating the effects of tidal forces, and observed as behaviours associated with tides began anew. Then, despite instituting numerous circadian-rhythm-disrupting methods (putting the creatures under constant light, knocking down circadian rhythmicity gene expression through RNAi, etc), they were not able to affect this tidal rhythmicity, suggesting that the two clocks operate independently.
With the bristle worm, the researchers tried administering drugs to interrupt their circadian clock mechanisms, but found that the animals’ lunar cycling was unaffected. However, they did observe that the circadian behaviours did appear to differ slightly between lunar phases, as did the abundance of molecules known to be involved in the circadian clock, suggesting that the bristle worms possess independent, endogenous monthly and daily body clocks that interact.
I think it’s going to be very interesting learning what molecules, which genes, and which epigenetic changes are part of these various mechanisms – and using that knowledge to discover what kind of analogues exist in humans.
News source: http://bit.ly/1fuMMFB
Image: Eurydice pulchra. bathyporeia/Flickr