Figure 4.

RecF and RecR cells are less able to complete ongoing rounds of DNA replication. (A) Chloramphenicol or rifampicin was added to cells prelabeled with [³H]thymine, and their ability to complete ongoing rounds of DNA synthesis as measured by net increase in DNA was analyzed. ▪, Wild type; •, recF; ▴, recR. Chloramphenicol (solid line); rifampicin (broken line). (B) Chloramphenicol and cephalexin were added to cells prelabeled with [³H]thymine, and incubation continued for 3 h. The cells then were analyzed by FACS to determine the DNA content per cell.