The research group of Assistant Professor Taichi Ito of Kyushu University Institute of Core Education and 4th year student of the Faculty of Science (at the time of research), in collaboration with Ulsan University of Science and Technology in the Republic of Korea, has only a primitive nervous system and no brain. We discovered that sleep is present in hydra and that its regulators are common to other animals.
Sleep is observed in a wide range of animal species and is thought to be closely associated with brain function.The research group focused on hydra, an animal that has not evolved to acquire a brain.When we examined the presence or absence of sleep phenomena, we found that the hydra had a clear sleep phase.Therefore, the research group compared the sleep mechanism between other animals and hydra, and aimed to elucidate the origin of the sleep mechanism.
When various bioactive substances were administered to hydra and changes in sleep length were investigated, sleep was promoted by both hypnotics (melatonin, GABA) and stimulants (dopamine).Next, we comprehensively analyzed the gene expression of hydra that had been deprived of sleep.Among the genes whose expression fluctuated, a protein (cGMP-dependent protein kinase) that has been pointed out to be related to sleep control in various animal species is included, and this substance was also involved in sleep control in hydra. ..
Furthermore, when the genes whose expression levels were changed in the deprived hydra were inhibited in Drosophila, multiple genes were involved in the control of sleep length in Drosophila.This indicates that the genes involved in hydra sleep also have a sleep-regulating effect in Drosophila.It has also been shown that some sleep control mechanisms may have been reorganized at the evolutionary stage of brain acquisition.
The results show that the research group is the first in the world to experimentally prove that "animals may have acquired sleep at the mechanical level prior to the evolution of the brain."
Paper information:[Science Advances] A sleep-like state in Hydra unravels conserved sleep mechanisms during the evolutionary development of the central nervous system
