A newly discovered gene called double-time regulates the molecular cycles underlying circadian rhythms, scientists from The Rockefeller University report in two papers featured on the cover of the July 10 issue of Cell. The researchers also identified the molecular mechanism that allows this gene to work.
"We've identified a gene in the fruit fly Drosophila that times the pairing of two proteins essential for circadian rhythms," says senior author Michael W. Young, Ph.D., professor and head of the Laboratory of Genetics at The Rockefeller University. Young also directs the National Science Foundation (NSF) Science and Technology Center for Biological Timing at Rockefeller.
Earlier studies have indicated that the genes and proteins governing circadian rhythms in Drosophila play a similar role in humans. In humans, daily circadian rhythms underlie many functions, including the sleep/wake cycle, body temperature, mental alertness, pain sensitivity and hormone production. In natural conditions, many rhythms have a 24-hour period related to sunlight, but though light can affect the rhythm, it does not cause the cycle. In fact, in the absence of light or other environmental clues, rhythms continue and most adapt to periods slightly longer or shorter than 24 hours.
In the fly, the circadian rhythm requires the pairing of two proteins, PER and TIM, made by the period (per) and timeless (tim) genes, respectively. All cells of the fly have per and tim genes, but the brain cells set the body clock. PER and TIM proteins accumulate in the nuclei of light-sensitive eye cells, called photoreceptors, as well as pacemaker cells of the central brain. Scientists at the California Institute of Technology discovered per in 1971, while Young's group identified tim in 1994.
In 1995, Young's laboratory showed how PER and TIM partner to control the fly's
body cycle. The fly circadian cycle begins around noon when the per
Contact: Joseph Bonner or Paul Focazio