June 20, 2005
Separating morning and evening in the circadian clock of mammals
Work by researchers at the Universities of Aberdeen and Nottingham suggests an anatomical basis for the adaptation of the mammalian circadian clock to changing day-length. Endogenous circadian clocks ensure that temporal patterns of physiology and behavior predict environmental changes determined by the Earth's rotation and orbit of the Sun. Such clocks are synchronized by the daily light-dark cycle.
A key question for circadian biologists concerns the way in which seasonal changes in day-length alter the behavior of circadian clocks over the course of the year. One idea for which evidence has accumulated is that circadian clocks contain coupled "morning" and "evening" oscillators that are separately synchronized to dawn and dusk.
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