The 24 hour molecular oscillator requires precisely calibrated degradation of core clock proteins, like PERIOD. New studies shed light on a sequential series of PERIOD phosphorylation events that first inhibits, then accelerates PERIOD degradation.

Tooth enamel contains relics of its formation process, in the form of microstructures, which indicate the incremental way in which it forms during enamel formation on teeth (). These microstructures, called cross-striations and striae of Retzius, develop as enamel-forming cells called ameloblasts, which cyclically deposit enamel on developing teeth in accordance with two different biological cl...

The 2017 Nobel Prize for Physiology or Medicine, awarded for the discoveries made in the past 15 years on the genetic and molecular mechanisms regulating many physiological functions, has renewed the attention to the importance of circadian rhythms. These originate from a central pacemaker in the suprachiasmatic nucleus in the brain, photoentrained via direct connection with melanopsin containi...

How do circadian rhythms, alarm clocks and the light/dark cycle interact? The concept of social jetlag is informing our appreciation of the tensions and consequences of imposing an artificial temporal order upon our biology.

Genetic Regulatory Networks (GRNs) are the control systems of all cells. Their dynamics are of crucial importance in development [4] but also in the ongoing, reactive, metabolism [1]. A characteristic example of such responsive regulation are circadian rhythms, which were present already in early life forms [10]. Following Winfree [10, 11], we ask 1) How is it that biological clocks can adapt, ...

Circadian timing is a fundamental biological process, underlying cellular physiology in animals, plants, fungi, and cyanobacteria. Circadian clocks organize gene expression, metabolism, and behavior such that they occur at specific times of day. The biological clocks that orchestrate these daily changes confer a survival advantage and dominate daily behavior, for example, waking us in the morni...

The recognition of the complexity underlying biological phenomena has renewed interest in systems biology approaches. Due to the critical role biological clocks play in a number of physiologically and clinically relevant situations, we utilize integrative quantitative approaches to reverse-engineer the mechanisms underlying the generation of the circadian rhythms from the synchronization of noi...

Rhythmically oscillating phenomena in biological systems have been analyzed in many ways: behaviorally (reviews: Moore-Ede et al 1982, Saunders 1982), neurobiologically (reviews: Turek 1985, Jacklet 1985), and biochemically (reviews: Takahashi & Menaker 1984, Johnson & Hastings 1986). Over the last four years, another angle from which these rhythms has been approached-"clock genetics"-appears t...

Circadian rhythms are biological processes displaying endogenous and entrainable oscillations of about 24 h. In mammals the sleep/wake cycle, core body temperature fluctuation, and diurnal variation of blood pressure and heart rate are among the most well-known circadian rhythms. These rhythms are not just the consequence of activity/rest cycles, but are also controlled by molecular clocks, a b...