Fig. 4. Mitosis in the tub1-Glu bim1 kip2 strain. We monitored mitosis in the tub1-Glu bim1 kip2 strain using GFP-tub1-Glu fusion integrated at the URA3 locus. (A) Viable cells from the tub1-Glu bim1 kip2 strain grew as well as the corresponding wild-type-tubulin TUB1 bim1 kip2 strain. (B) Illustration of MT behaviour. (Left) Contrast-phase image of cells; (right) fluorescent image of tub1-Glu-GFP cells. Astral MTs are visible at different cell stages (arrows). (C) Selected frames from a representative time-lapse series used to analyze mitosis. Astral MTs are not detectable. We imaged spindles that elongate in the mother cell. Finding the neck lumen was apparently problematic for the spindle and this delayed the penetration of the elongating spindle into the bud. (D) Selected frames from a representative time-lapse series of spindle bending in the mother cell. (B-D) The time is in hours:minutes. Scale bars: 3 µm. (E) Quantitative analysis of the percentage of spindles in contact with the cell cortex prior to passage of the spindle through the neck. 15 films were scored for each strain. Bars are s.e.m.