FIGURE 7:

Human cells expressing MTBP without a functional CTM domain exhibit diminished origin firing. (A) Schematic of procedure for labeling of DNA fibers. Human cells expressing wild-type (WT) and ∆C versions of MTBP were treated with siRNA, labeled sequentially with CldU and IdU, and processed for DNA combing as described under Materials and Methods. (B) Representative images used for determination of replication fork velocities. Arrows indicate the lengths of tracks used for measurement of fork velocities. (C) Quantitation of replication fork velocities in cells expressing MTBP-WT or MTBP-∆C. Three independent experiments were performed with measurement of more than 150 fibers each. A Mann-Whitney U test yielded p < 0.001. Box plot depicts second quartile, median, and third quartile. (D) Representative images used for determination of inter-origin distances. (E) Quantitation of inter-origin distances in cells expressing MTBP-WT or MTBP-∆C. Results are compilation of two independent experiments with 50 random samples measured for each condition in each experiment. A Mann-Whitney U test yielded p < 0.001. Box plot depicts the second quartile, median, and third quartile.