Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.
J Biol Rhythms. 2010 Dec;25(6):442-9. doi: 10.1177/0748730410385281.
Although overt diurnal rhythms of behavior do not begin until well after birth, molecular studies suggest that the circadian clock may begin much earlier at a cellular level: mouse embryonic fibroblasts, for example, already possess robust clocks. By multiple criteria, we found no circadian clock present in mouse embryonic stem cells. Nevertheless, upon their differentiation into neurons, circadian gene expression was observed. In the first steps along the pathway from ES cells to neurons, a neural precursor cell (NPC) line already showed robust circadian oscillations. Therefore, at a cellular level, the circadian clock likely begins at the very earliest stages of mammalian development.
虽然明显的昼夜行为节律直到出生后很久才开始，但分子研究表明，生物钟可能在细胞水平上更早开始：例如，小鼠胚胎成纤维细胞已经拥有强大的时钟。根据多项标准，我们发现小鼠胚胎干细胞中没有生物钟。然而，当它们分化为神经元时，观察到了生物钟基因的表达。在从 ES 细胞到神经元的途径的第一步中，神经前体细胞 (NPC) 系已经显示出强大的昼夜节律波动。因此，在细胞水平上，生物钟可能在哺乳动物发育的最早阶段就开始了。
