Biological rhythms are pervasive in nature, yet our understanding of the molecular mechanisms that govern timing is far from complete. The rapidly emerging research focus on epigenetic plasticity has revealed a system that is highly dynamic and reversible. In this Opinion, I propose an epigenetic clock model that outlines how molecular modifications, such as DNA methylation, are integral components for timing endogenous biological rhythms. The hypothesis proposed is that an epigenetic clock serves to maintain the period of molecular rhythms via control over the phase of gene transcription and this timing mechanism resides in all cells, from unicellular to complex organisms. The model also provides a novel framework for the timing of epigenetic modifications during the lifespan and transgenerational inheritance of an organism.

生物节律本质上是普遍存在的，但是我们对控制时间的分子机制的理解还远远不够。关于表观遗传可塑性的迅速发展的研究表明，该系统具有高度的动态性和可逆性。在此意见中，我提出了一个表观遗传时钟模型，该模型概述了分子修饰（例如DNA甲基化）如何构成计时内源性生物节律的组成部分。提出的假设是表观遗传钟通过控制基因转录的阶段来维持分子节律的周期，这种计时机制存在于从单细胞到复杂生物的所有细胞中。该模型还为生物的寿命和跨代遗传中的表观遗传修饰的时间提供了一个新颖的框架。