Evidence for Sequential and Increasing Activation of Replication Origins along Replication Timing Gradients in the Human Genome
Figure 3
Replication timing profiles segmented in CTRs/TTRs and multiscale analysis of apparent replication speeds in HeLa cells.
(A) Profile of replication timing (TR50, hours) along a 15 Mb segment of chromosome 17. Small TR50 values correspond to early replicating regions; large TR50 values correspond to late replicating regions. The replication timing profile was segmented into regions that replicate at apparent speed >10 kb/min (CTRs: Constant Timing Regions, red horizontal lines) and <10 kb/min (TTRs: Timing Transition Regions, green oblique lines) at scale 100 kb. (B) Multiscale analysis of apparent replication speeds along the same chromosome segment. Replication speeds determined by wavelet transform analysis (see Material and Methods) at scales indicated on the y-axis are shown in three colors (blue, <2 kb/min; green, from 2 to 10 kb/min; red, >10 kb/min). (C) Distribution of apparent replication speed at the 100 kb scale in the whole genome (pdf: probability density function). (D) Distribution of apparent replication speeds in the four temporal compartments of S phase: S1, S2, S3 and S4 (respectively: blue, green, pink, and red curves).