Fig. 4

Kinetics of Dp-1 DNA replication. S. pneumoniae R6 WT (a) and R6-DP1^R (b) were infected with the lytic phage Dp-1 at a MOI of 0.1. Total DNA was extracted at baseline and at 15, 30, 45, 60 and 90 min after infection. Total DNA was digested with SspI before being hybridized with an [α-³²P]dCTP-labeled probe covering the holin gene of DP-1. DNA loading was controlled by hybridizing the blots with an [α-³²P]dCTP-labeled probe covering the spr1443 gene from S. pneumoniae R6. Holin/spr1443 signal ratios are indicated in italics below the blots. Hybridizations were done in triplicates and representative blots are shown. c Plot of holin/spr1443 signal ratios for S. pneumoniae R6 WT (black) and R6-DP1^R (dark grey). The R6-DP1^R ratios from 45 to 90 min were significantly different (p < 0.001 by two-way ANOVA) than those of R6 WT