Figure 5. Parachlamydiaceae-induced changes in nuclear morphology in S2 cells depend on bacterial activity.

S2 cells were either left untreated or were treated with SPG buffer, amoebal lysate, infectious Parachlamydiaceae (Pa. acanthamoebae or P. amoebophila; MOI 5) in the absence (Inf) or presence of the protein synthesis inhibitor doxycycline (Inf-Dox), heat-inactivated bacteria (Hi), UV- inactivated bacteria (UVi), a sterile-filtrate of the suspension of purified infectious bacteria (Filtrate) or a supernatant collected 48 h p.i. from an infected (MOI 5) apoptotic culture (Supernatant). For comparison, cells treated with infectious S. negevensis Z (MOI 5 or 50, as indicated) are shown. After 48 h incubation, DNA was stained with DAPI and the proportion of nuclei with altered morphology was determined. Mean values and standard deviations of six replicates (derived from three independent experiments) are shown. At least 500 nuclei per replicate were considered. Statistically significant differences compared to the untreated cells are indicated (ANOVA & Scheffé; ***, p≤0.001; **, p≤0.01; *, p≤0.05).