Figure 5.

Negative control for the DSB dynamics. (A) A control HeLa nucleus (top row) and an NCS-treated (500 ng/mL) nucleus upon ATP depletion (bottom row) are shown. 53BP1-mCherry (red) and H2B-GFP (green) signals visualize the DNA repair foci and chromatin, respectively. (B) Histograms of I_ch and S_rel for random chromatin sites (gray) at periphery and interior of control nuclei are given. From these distributions, we extract a subpopulation of random sites in undamaged nuclei, which has I_ch and S_rel distributions comparable to the ones measured for real DSBs (solid purple lines) in the interior and periphery (orange), respectively. (C) Distributions of A_s, α, and A_L for DSBs measured at all 3 NCS concentrations (200, 500, and 800 ng/mL), an NCS (500 ng/mL)-treated nuclei upon ATP depletion, and the mock DSBs identified in (B) are shown. (D) MSDs for all samples from (C) are shown. MSD measured for DSBs in damaged cells fixed in formaldehyde (black line, N_DSB = 152, N_Cells = 42) and mock DSBs in undamaged (control) cells fixed in formaldehyde (gray line, N_DSB = 165, N_Cells = 12) defines the noise floor for DSBs and mock DSBs, respectively. (E) Relationship between I_ch and A_L for interior DSBs from (C) is shown. Error bars for (D) and (E) are shown in Fig. S4. Scale bars, 5 μm. To see this figure in color, go online.