Figure 4.

The variabilities of the inter-origin distances, σ_d, and of the firing strengths, σ_λ, set the replication regime. (A, B) Average S phase duration (top panels) and its standard deviation (bottom panel) as functions of σ_d (panel A) or σ_λ (panel B), obtained by simulations of the model (blue circles and lines) and by the EVD estimate (green triangles and lines). Fifty samples of inter-origin distances and origin strengths are chosen according to the distributions in Eq. (2). Red lines indicate the transition points where the simulated 〈〈T_S〉〉 is 20% larger than at σ_d = 0 and σ_λ = 0. The border lines of the grey area show the transition points for 〈〈T_S〉〉 + σ (〈T_S〉) and 〈〈T_S〉〉 − σ (〈T_S〉) respectively. (C) Phase diagram separating the EVD and bottleneck regimes. Red transition points with error bars (obtained with the method shown in (A) and (B)) form an approximate rectangle phase boundary. Parameters: fork velocity = 1.81 kb/min, origin number n = 20, γ = 1.5, 〈d〉 =28.13 kb, 〈λ〉 =6.17 × 10⁻⁴ min ^−2.5, σ_λ = 0 (A) and σ_d = 0 (B).