Evidence for Sequential and Increasing Activation of Replication Origins along Replication Timing Gradients in the Human Genome
Figure 5
Replication Speeds along TTRs.
(A) Size and replication time of individual TTR. The time difference, Dt, between the early and the late side of each TTR is plotted along its length, Dx, for each of the 7504 TTRs (open circles). By definition, the maximum replication speed of TTRs is 10 kb/min (dark blue line). The mean apparent replication speed, Dx/Dt, is 3.63 kb/min (green dashed line). The mean (v = 0.64 kb/min, red line) and maximum (v = 2 kb/min, orange line) velocities of single forks measured by DNA combing are indicated. Only 24 TTRs lie between the orange line and the vertical axis. (B) Evolution of apparent replication speed along the 774 TTRs>400 kb. The apparent speed measured at the distance D4 = 400 kb from early edge of each TTR is plotted against the apparent speed measured at the distance D1 = 100 kb. Replication accelerates for 62% of TTRs. (C) Distribution of apparent replication speeds along the 774 TTRs>400 kb. The apparent speed has been measured at different distances D1–D4 from early edge of each TTR: D1 = 100 kb, red curve; D2 = 200 kb, green curve; D3 = 300 kb, blue curve; D4 = 400 kb, grey curve.