Figure 2.

Val1686 is required for V. alginolyticus T3SS-induced apoptosis. (A) TUNEL assay. FHM cells were either uninfected, or infected (m.o.i. = 10) with wild-type ZJO (WT), deletion mutant and complementation strains as indicated. At 1 h and 2 h after infection, DNA fragmentation was detected by TUNEL staining. TUNEL-positive cells were quantified from three independent experiments and the data are presented as means ± SEM. At least four fields under light microscopy (40 × objective) were randomly selected and examined for each experiment. (B) Measurement of caspase-3 activity of infected cells as described for TUNEL assay. The data are expressed as fold-increase compared to the corresponding values of caspase activity in uninfected cells (Ctrl) (error bars = SEM; 3 independent experiments). Statistical analysis was performed by using a Kruskal Wallis test followed by a Tukey-Kramer multiple comparisons test between the treatment groups and the control. Asterisks indicate significance for both 1- and 2-hour time points compared to controls (***; P < 0.001).