FIGURE 4 

Direct observation of incomplete induction in a subpopulation of cells, following irradiation with a UV dose of 5 J/m². Whereas some cells harboring pR-GFP reporter plasmids (blue traces) complete the lytic cascade and exhibit promoter activity profiles (A) similar to those observed after irradiation with a high dose (see Figure 2C), a subpopulation of cells do not lyse, go through cell division after an 50 min delay and exhibit promoter activities (B) that are typically lower than cells that lyse. Similar experiments carried out with cells harboring pR'-tR'-GFP reporter plasmids (red traces) also show differences in promoter activity profiles between cells that lyse (C) and cells that undergo incomplete induction (D).