Supplementary Figure 3: Chromosome segregation and cytokinesis in ycg1-2 and top2-4 cells.
(a) Anaphase progression in top2-4 cells with fluorescently tagged histone (Htb2) and myosin (Myo1). Numbers indicate time in minutes. Scale bar is 2 μm. The graphs show the time of actomyosin ring contraction relative to nuclear elongation (left) and the duration of contraction (right), in the indicated cell types. Line represents the mean. n = 50 (wild type), 32 (ycg1-2), 34 (top2-4), where n = number of cells pooled from two experiments. (b) Time-lapse imaging was used to determine the percentage of cells with Mre11-GFP foci after nuclear elongation in the indicated strains. n = 98 cells (wild type), 46 (ycg1-2), 40 (top2-4), where n = number of cells pooled from two experiments. (c) Time of appearance of the next bud after cytokinesis (rebudding) relative to the time of membrane closure (GFP-CAAX). Number of cells (pooled from two independent experiments): n = 35 (wild type), 38 (ycg1-2), 52 (top2-4). The rebudding kinetics of wild type and mutant cells were considered significantly different (P < 0.0001, Mann-Whitney test). (d) Slices from a tomogram of the septum in a top2-4 cell. Arrowheads point to nuclear membrane entering the channel (left); Arrows point to plasma membrane underlying the channel (right). Scale bars are 0.2 μm. (e) Serial ultra-thin sections (60-70 nm) from wild type and ycg1-2 cells 3 h after release from a G1 block. Septum channels were present in all examined ycg1-2 mutant cells (9), whereas all wild-type cells showed intact septa (13). Continuous septum deposition might constrict these channels and lead to their delayed closure. Arrows point to lacunae traversing the septum of the mutant. PS, primary septum, SS, secondary septum. Scale bar is 0.5 μm.
