How plankton gets jet lagged
A hormone that governs sleep and jet lag in humans may also drive the mass migration of plankton in the ocean, scientists at the European Molecular Biology Laboratory (EMBL) in Heidelberg, Germany, have found. The molecule in question, melatonin, is essential to maintain our daily rhythm, and the European scientists have now discovered that it governs the nightly migration of a plankton species from the surface to deeper waters. The findings, published online today in Cell, indicate that melatonin’s role in controlling daily rhythms probably evolved early in the history of animals, and hold hints to how our sleep patterns may have evolved.[…]
[The researchers] discovered a group of specialised motor neurons that respond to melatonin. Using modern molecular sensors, [they were] able to visualise the activity of these neurons in the larva’s brain, and found that it changes radically from day to night. The night-time production of melatonin drives changes in these neurons’ activity, which in turn cause the larva’s cilia to take long pauses from beating. Thanks to these extended pauses, the larva slowly sinks down. During the day, no melatonin is produced, the cilia pause less, and the larva swims upwards.
“Step by step we can elucidate the evolutionary origin of key functions of our brain. The fascinating picture emerges that human biology finds its roots in some deeply conserved, fundamental aspects of ocean ecology that dominated life on Earth since ancient evolutionary times”
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