Figure 4.

Normal pRE Activation without DNA Replication

(A) Representative images of lytic and lysogenic events by λWT infections at MOI = 1. Top: expression of gpD-EYFP (green) is observed and the cell lyses at 95 min. Bottom: increase of mCherry (red) expression and normal cell division is observed, indicating a successful lysogenic event.

(B) Representative images showing λP^- infections at MOI = 1. Top: increase in mCherry expression is observed, indicating the activation of pRE promoter. Low levels of gpD-EYFP expression are also detected in the cell. Bottom: only a very low level of gpD-EYFP expression is observed. Division is inhibited, and the cell keeps growing longer without lysing. Same contrast was applied to the images in (A) and (B) at 65 and 95 min. At 0 min, a different contrast if applied to see the green phage particles.

(C) Percentages of cells with pRE activation at different MOIs. Both phages show similar levels of pRE activation at different MOIs. Error bars denote SEM.

Scale bars denote 2 μm.