Molecular regulation of sleep in the upside-down jellyfish Cassiopea

The conservation of sleep among diverse animals provides clear evidence for its physiological importance, but the extent of its regulatory conservation is unknown. The upside-down jellyfish Cassiopea xamachana exhibits sleep-like behavior, satisfying the three criteria of sleep: 1) behavioral quiescence that is reversible 2) latency-to-arousal, or, reduced responsiveness to stimuli during the quiescent state, and 3) homeostatic rebound in response to disruptions to the nighttime quiescent period (i.e. sleep deprivation). To understand the molecular mechanisms underlying sleep regulation in Cassiopea, we compared gene expression profiles of ganglia from animals deprived of sleep across two experiments. In the first experiment, adult jellyfish were deprived of sleep with periodic exposure to light during their nighttime quiescent period. In the second experiment, animals were sleep deprived using mechanical stimulus.