An evolutionary link between sleep and rhythmic swimming behaviour
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.
Every night, an increase in melatonin levels in this larva's brain makes it move away from the sea's surface. Credit: EMBL/M.A.Tosches
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.
In vertebrates, melatonin is known to play a key role in controlling daily activity patterns – patterns which get thrown out of synch when we fly across time zones, leading to jet lag. But virtually all animals have melatonin. What is its role in other species, and how did it evolve the task of promoting sleep?
To find out, Detlev Arendt’s lab at EMBL turned to the marine ragworm Platynereis dumerilii. This worm’s larvae take part in what has been described as the planet’s biggest migration, in terms of biomass: the daily vertical movement of plankton in the ocean.
By beating a set of microscopic ‘flippers’ – cilia – arranged in a belt around its midline, the worm larvae are able to migrate toward the sea’s surface every day. They reach the surface at dusk, and then throughout the night they settle back down to deeper waters, where they are sheltered from damaging UV rays at the height of day.
“We found that a group of multitasking cells in the brains of these larvae that sense light also run an internal clock and make melatonin at night.” says Detlev Arendt, who led the research. “So we think that melatonin is the message these cells produce at night to regulate the activity of other neurons that ultimately drive day-night rhythmic behaviour.”
Maria Antonietta Tosches, a postdoc in Arendt’s lab, discovered a group of specialised motor neurons that respond to melatonin. Using modern molecular sensors, she was 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.
“When we exposed the larvae to melatonin during the day, they switched towards night-time behaviour,” says Tosches, “it’s as if they were jet lagged.”
The work strongly suggests that the light-sensing, melatonin-producing cells at the heart of this larva’s nightly migration have evolutionary relatives in the human brain. This implies that the cells that control our rhythms of sleep and wakefulness may have first evolved in the ocean, hundreds of millions of years ago, in response to pressure to move away from the sun.
“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,” Arendt concludes.
The work was partly funded by the European Research Council grant BrainEvoDevo.
Published online in Cell on 25 September 2014. DOI: 10.1016/j.cell.2014.07.042
For images, video and more information please visit: www.embl.org/press/2014/140925_Heidelberg.
Policy regarding use
EMBL press and picture releases including photographs, graphics and videos are copyrighted by EMBL. They may be freely reprinted and distributed for non-commercial use via print, broadcast and electronic media, provided that proper attribution to authors, photographers and designers is made.
Sonia Furtado Neves
EMBL Press Officer & Deputy Head of Communications
Meyerhofstr. 1, 69117 Heidelberg, Germany
Tel.: +49 (0)6221 387 8263
Fax: +49 (0)6221 387 8525
Sonia Furtado Neves | EMBL Research News
First time-lapse footage of cell activity during limb regeneration
25.10.2016 | eLife
Phenotype at the push of a button
25.10.2016 | Institut für Pflanzenbiochemie
Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.
This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
25.10.2016 | Earth Sciences
25.10.2016 | Power and Electrical Engineering
25.10.2016 | Process Engineering