3 years ago

The Jellyfish Cassiopea Exhibits a Sleep-like State

The Jellyfish Cassiopea Exhibits a Sleep-like State
Lea Goentoro, Paul W. Sternberg, Michael J. Abrams, David A. Prober, Viviana Gradinaru, Ravi D. Nath, Justin S. Bois, Ty Basinger, Claire N. Bedbrook

Summary

Do all animals sleep? Sleep has been observed in many vertebrates, and there is a growing body of evidence for sleep-like states in arthropods and nematodes [1–5]. Here we show that sleep is also present in Cnidaria [6–8], an earlier-branching metazoan lineage. Cnidaria and Ctenophora are the first metazoan phyla to evolve tissue-level organization and differentiated cell types, such as neurons and muscle [9–15]. In Cnidaria, neurons are organized into a non-centralized radially symmetric nerve net [11, 13, 15–17] that nevertheless shares fundamental properties with the vertebrate nervous system: action potentials, synaptic transmission, neuropeptides, and neurotransmitters [15–20]. It was reported that cnidarian soft corals [21] and box jellyfish [22, 23] exhibit periods of quiescence, a pre-requisite for sleep-like states, prompting us to ask whether sleep is present in Cnidaria. Within Cnidaria, the upside-down jellyfish Cassiopea spp. displays a quantifiable pulsing behavior, allowing us to perform long-term behavioral tracking. Monitoring of Cassiopea pulsing activity for consecutive days and nights revealed behavioral quiescence at night that is rapidly reversible, as well as a delayed response to stimulation in the quiescent state. When deprived of nighttime quiescence, Cassiopea exhibited decreased activity and reduced responsiveness to a sensory stimulus during the subsequent day, consistent with homeostatic regulation of the quiescent state. Together, these results indicate that Cassiopea has a sleep-like state, supporting the hypothesis that sleep arose early in the metazoan lineage, prior to the emergence of a centralized nervous system.

Publisher URL: http://www.cell.com/current-biology/fulltext/S0960-9822(17)31023-0

DOI: 10.1016/j.cub.2017.08.014

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