Expression of a Novel P22 ORFan Gene Reveals the Phage Carrier State in Salmonella Typhimurium
Figure 9
Pid expression is linked to phage carrier cells.
Exponential phase cultures of LT2 pCW-mCherry-parB were infected with P22 Δpid::yfp parS (MOI = 0.1) and chased after 30 minutes with the virulent P22 H5 mutant (MOI = 20) to lyse cells not destined for non-lytic development of P22 Δpid::yfp parS. Two independent time-lapse fluorescence microscopy image sequences (A and B) of an LT2 pCW-mCherry-parB cell destined for non-lytic development of P22 Δpid::yfp parS are shown. The corresponding phase contrast images are either superimposed with YFP epifluorescence images visualizing pid expression (left panels) or mCherry epifluorescence images visualizing the presence of the P22 chromosome(s) (right panels), and the time after infection is indicated on the frames. Please note that only the carrier cell produces new YFP, while non-carrier segregants passively acquire preformed YFP by cytoplasmic diffusion, and further dilute it upon subsequent cell divisions.