Figure 6. S. aureus induced dose-dependent G2/M phase transition delay in the subsequent G2/M phase.

A. HeLa cells were synchronized by DTB and were exposed to S. aureus bacteria (MW2) at MOI 20∶1 or to the media alone for 2 h, followed by incubation in cDMEM-Gent100 for 2 h, and subsequently incubated for an additional 12 h, 14 h, 18 h, 20 h and 24 h. Detached cells were then combined with adherent cells and stained with PI. Cell cycle phases of PI-stained cells were monitored by FACS. The data were collected from 20,000 cells and analysis was performed with Cell Quest software. Each experiment was performed four times. The number of cells in different phases is presented on the histograms. The values shown are those of a representative assay out of the four assays performed. Exposure of the cells to S. aureus bacteria induced a G2/M phase transition delay in a time-dependent manner. B. HeLa cells were synchronized by DTB and were exposed to S. aureus bacteria (MW2) at different MOIs ranging from 5∶1 to 20∶1, followed by incubation in cDMEM-Gent100 for 2 h, and further incubated for an additional 20 h. Detached cells were then combined with adherent cells and stained with PI. Cell cycle phases of PI-stained cells were monitored by FACS. The data were collected from 20,000 cells and analysis was performed with Cell Quest software. The percentage of cells is presented on the graph as a function of bacterial concentration. The data correspond to a representative experiment out of the three assays performed and are presented as mean +/− SD. Tukey's Honestly Significant Difference test was applied for comparison of means between the groups. (*) P-values <0.05 compared with control were considered to be significant. Exposure of the cells to S. aureus bacteria induced a G2/M phase transition delay in a dose-dependent manner.