Polymerase-Usage Sequencing Identifies Initiation Zones with Less Bias Across S phase in Mouse Embryonic Stem Cells.

Abstract

Various methods have been developed to map replication initiation zones (IZs) genome-wide, often finding far fewer IZs than expected. In particular, IZs corresponding to later stages of S phase are under-represented. Here, we re-analyzed IZs with respect to replication timing in mouse ES cells. These data sets identified over five times as many early IZs compared to late-IZs. In addition, we have set up a polymerase-usage sequencing (Pu-seq) system in mouse ES cells to map IZs genome-wide. Pu-seq showed less bias towards early IZs, potentially indicating better sensitivity for identifying IZs in late S phase.