Figure 4—figure supplement 1.

(A) Confocal z-projections of stills from confocal time lapse of Mrab25b mononucleate EVL cell during mitosis at 30% epiboly. Microtubules (green), membrane (magenta), and nuclei (magenta). Arrowhead indicates reduced density of astral microtubules. Relative proportions of spindle orientations along the long axis of cells during mitosis. Scale bar 20 μm. (B) Confocal z-projections of stills from confocal time lapse of Mrab25b mitotic spindles fusing during multipolar cytokinesis. Time-lapses began at 30% epiboly in marginal regions; arrows denote fusing spindles: Microtubules (green), membrane (magenta), and nuclei (magenta). Scale bar 10 μm. (C) Confocal z-projections of stills from confocal time lapse of a WT embryo imaged beginning at dome stage. Shaded cells are dividing; Nuclei and membranes labeled. Scale bar 20 μm. (D) Confocal z-projections of stills from confocal time lapse of multipolar mitosis in MZrab25b embryos beginning at 30% epiboly. Failed cleavage indicated by arrows; Successful cleavage generates cells with reduced apices indicated by numerals; Nuclei and membranes labeled. Scale bar 10 μm. (E) Confocal z-projection of a MZrab25b EVL cell expressing mGfp undergoing basal cell extrusion. Scale bar 10 μm. (F) Quantifications of means of (1) proliferation events in WT (n = 5), MZrab25a (n = 7) and MZrab25b (n = 7);(2) Cytokinesis events in WT (n = 9), MZrab25a (n = 13) and MZrab25b (n = 9); (3) non-sister cell fusions in WT (n = 5), MZrab25ba (n = 7) and MZrab25b (n = 7); (4) Basal Cell Extrusion events in WT (n = 8), MZrab25a (n = 7) and MZrab25b (n = 9). Means: SEM; One-Way ANOVA; *, **, ***, ****, p<0.05, 0.01, 0.001, 0.0001.