McClung C Robertson
Department of Biological Sciences, 6044 Gilman Laboratories, Dartmouth College, Hanover, NH 03755-3576, USA.
Curr Opin Plant Biol. 2008 Oct;11(5):514-20. doi: 10.1016/j.pbi.2008.06.010. Epub 2008 Aug 3.
The circadian clock is a selfsustaining oscillator with an endogenous period of approximately 24 hours. The Arabidopsis clock is composed of a set of interlocking negative feedback loops entailing transcriptional, post-transcriptional, and post-translational, particularly regulated proteolysis, control. Clock control of the transcriptome is widespread; up to 90% of the transcriptome cycles in at least one condition in seedlings exposed to a variety of environmental cycles. Clock control extends to the metabolome, though diurnal oscillations in enzyme activities and metabolites are less dramatic than oscillations in cognate transcripts. Metabolites, including organic nitrogen intermediates, feed back to modulate clock function, consistent with the view of the circadian clock as a key integrator of metabolic signals to coordinate metabolism and physiology with the environment.
生物钟是一种自我维持的振荡器，其内在周期约为24小时。拟南芥生物钟由一组相互连锁的负反馈环组成，涉及转录、转录后和翻译后（特别是受调控的蛋白水解）控制。生物钟对转录组的控制非常广泛；在暴露于各种环境周期的幼苗中，至少在一种条件下，高达90%的转录组会循环。生物钟控制延伸到代谢组，尽管酶活性和代谢物的昼夜振荡不如同源转录本中的振荡那么显著。包括有机氮中间体在内的代谢物会反馈调节生物钟功能，这与生物钟作为代谢信号的关键整合者，以协调代谢和生理与环境的观点一致。
