News of the WeekCircadian Rhythms

Possible Clock Messenger Identified

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Science  24 Dec 1999:
Vol. 286, Issue 5449, pp. 2434-2436
DOI: 10.1126/science.286.5449.2434b

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Organisms from bacteria to humans have 24-hour clocks that regulate many daily activities. To impose their rhythms, the molecules that make up these circadian clocks must communicate, through some kind of outgoing signals, to the brain areas that drive behaviors. In this week's issue of Cell, researchers report on the first good candidate for such a messenger in fruit flies: a peptide called PDF that is a key outgoing clock signal. The researchers have shown that flies in which the pdf gene has been inactivated have functional clocks but lose their rhythmic activity patterns under certain conditions, suggesting that a signal from the clock that affects activity is missing.