Dynamics of replication timing during mammalian development

Recent developments in low-input genomics techniques have greatly advanced the analysis of the order in which DNA is replicated in the genome – that is, replication timing (RT) – and its interrelationships with other processes. RT correlates or anticorrelates with genomic-specific parameters such as gene expression, chromatin accessibility, histone modifications, and the 3D structure of the genome, but the significance of how they influence each other and how they relate to biological processes remains unclear. In this review I discuss the results of recent analyses of RT, the time at which it is remodeled and consolidated during embryogenesis, how it influences development and differentiation, and the regulatory mechanisms and factors involved.