Fig. 3. Phenotypic analysis of wild-type and mutant cells in which cytokinesis A and/or B has been disrupted. (A,B) Histograms showing the distributions of nuclei/cell among cells grown in suspension (B) or on glass surfaces (A). Cells of all three strains shown were cultured in suspension before being transferred to plastic Petri dishes with thin glass bottoms; fixation, DAPI staining and counting of nuclei were performed immediately (B) or after 3 days of continued growth on the glass surface (A). (C-I) Photomicrographs of cells grown for 3 days on a glass surface. Unlike cells shown in A and B, these cells were precultured on plastic Petri dishes, suspended by streams of medium using micropipettes, diluted, and replated to plastic Petri dishes with thin glass bottoms because cells carrying the mhcA^- mutation were unable to grow in suspension. Wild-type (C) and mhcA^- cells (D) were mostly mononucleate. AmiA^- (E), corA^- (G) and amiA^-/corA^- (I) cells were somewhat larger and flatter than wild-type cells, indicating moderate disruption of cytokinesis. The greater enlargement of amiA^-/mhcA^- (F) and corA^-/mhcA^- (H) double knockout cells suggests cytokinesis is more severely affected in these strains. (J) A histogram showing the distributions of nuclei/cell among the cells shown in C-I. More than half of the amiA^-/mhcA^- and corA^-/mhcA^- cells are multinucleate, and more than 30% of them are highly multinucleate (more than five nuclei per cell), confirming severe disruption of cytokinesis in these cells. Magnifications in panels C-I are the same. Bar, 10 µm.