Abstract
The term 'circadian rhythm' describes an oscillatory behavior in the absence of exogenous environmental cues, with a period of about a day. As yet, we don't fully understand which biological mechanisms join together to supply a stable and self-sustained oscillation with such a long period. By chipping away at the molecular mechanism with genetic approaches, some common features are emerging. In combining molecular analyses and physiological experiments, those features that are crucial for structuring a circadian day could be uncovered.
