The location and development of Replicon Cluster Domains in early replicating DNA

We use a synchronisation protocol that gives a cohort of cells that enter S phase with a high degree of synchrony. At different times after release into S phase, we pulsed cells with EdU and sequenced the DNA replication ongoing during the length of time that these pulses lasted. Our high-resolution data shows the existence of discrete peaks of DNA synthesis within individual Early Timing Domains. The size of these peaks (~500 kb) is consistent with them representing individual replicon clusters, so we have named them ‘Replicon Cluster Domains’. The distribution and evolution of these Replicon Cluster Domains suggest that their activation varies between different cells in a population and shows a preference for a ‘domino’-type activation sequence.