Fluorescence microscopy images (A-F) of cells harboring control and toxic plasmids. Plasmids and host cells are indicated for each panel. While toxic constructs pCTXVP60 (B) or induced ORF238 (E,F) give rise to abnormally long cells, untransformed MG1655 cells (A) and uninduced ORF238 (C,D) cells displayed no defects. Insets of (A) and (B) show nonyl acridine orange-stained (green) membranes superimposed onto ethidium bromide stained (red) nucleoids. DAPI stained nucleoids (pseudocolored red) are shown in (C) and (E). Arrowheads in (B) and (E) indicate abnormal, stretched or multiple nucleoids in undivided cells. Scalebars: 2 μm.