Caenorhabditis elegans (C.elegans)
I’m sure like all of you with young kids, I don’t get enough sleep. I don’t need much naturally but an extra hour or so here and there would be great! The roundworm C. elegans, a staple of laboratory research, may be key in unlocking one of the central biological mysteries: why do we sleep?
Researchers at the University of Pennsylvania School of Medicine report in this week’s advanced online edition of Nature that the round worm has a sleep-like state, joining most of the animal kingdom in displaying this physiology. This research has implications for explaining the evolution and purpose of sleep and sleep-like states in animals.
In addition, genetic work associated with the study provides new prospects for the use of C. elegans to identify sleep-regulatory genes and drug targets for sleep disorders.
The research showed that there is a period of behavioral quiescence during the worm’s development called lethargus that has sleep-like properties. “Just as humans are less responsive during sleep, so is the worm during lethargus,” explains lead author David M Raizen. “And, just as humans fall asleep faster and sleep deeper following sleep deprivation, so does the worm.”
By demonstrating that worms sleep, Raizen and colleagues have not only demonstrated the need for sleep in nature, but also propose a compelling hypothesis for the purpose for sleep. The time of lethargus coincides with a time in the round worms’ life cycle when synaptic changes occur in the nervous system. In other words, in order for the nervous system to grow and change, there must be down time of active behavior. Other researchers at Pennsylvania have shown that, in mammals, synaptic changes occur during sleep and that deprivation of sleep results in a disruption of these synaptic changes - often resulting in changes to mood and normal behavior.
In addition, the research team used C. elegans as a model system to identify a gene that regulates sleep. This gene, which encodes a protein kinase and is regulated by a small molecule called cyclic GMP, has been previously studied but not suspected to play a role in sleep regulation. The findings suggest a potential role for this gene in regulating human sleep and may provide an avenue for developing new drugs for sleep disorders.
Elaine Warburton
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