Figure 5.

a) In vivo MMR of replication-competent plasmid. In vivo MMR assays were performed as described (materials and methods). The p220.pbc+H/B) plasmid contains a mammalian origin of replication and a site-specific G:T or G:A mismatch. HeLa cells enriched for each phase of the cell cycle by elutriation and transfected with the mismatch-containing plasmid were incubated for 2 hr. Total repair frequency above the MMR negative E. coli (NR9161) background was calculated and the percent of correct (nick-directed repair) versus incorrect (opposite nicked strand) MMR was determined from total repair frequency [27]. Negative MMR (proliferating HCT116) and positive MMR (proliferating HeLa) controls were incubated for 24 hr before plasmid was extracted. The bar graphs below the table is a graphical representation of the data within the table. The frequency above background of total repair for each mismatch at each phase of the cell cycle (black bars), and fractions of correct (nick-directed MMR; grey bars) and incorrect (opposite nicked strand; white bars) mismatch repair within each total repair frequency, were plotted separately as indicated. b) HeLa cell cycle progression during 2 hr incubation. Elutriated HeLa cell populations enriched for each phase of the cell cycle (bolded) were immediately transfected with the replication-competent plasmid and replated as described (materials and methods). Each fraction was subjected to flow cytometry immediately after transfection, as well as 2 hours after transfection. c) HeLa cell cycle progression during 24 hr incubation. Elutriated HeLa cells enriched for G₁ phase of the cell cycle were immediately transfected with the replication-competent plasmid and replated as described (materials and methods). Each fraction was subjected to flow cytometry immediately after transfection, as well as 24 hours after transfection.