Figure 6

Loss of partial or full cohesion leads to spindle elongation. US3329 (wild-type) and SL25 (scc1) cells were arrested by alpha-factor in G1 at 25°C and released in fresh YEPD containing 0.2 M HU for 3 hours at 25°C (A) and 32°C (B). Left panels show fields of mitotic spindles of strains as indicated. Corresponding spindle length distributions are shown in the right panels. 100-150 cells were analyzed in each case. C. DNA contents of cells determined by flow cytometry. Arrows indicate G1 and G2 DNA contents. D, E. Spindle elongation in scc1-73 cells transferred to 35°C shortly after exit from G1 arrest. SL25 (scc1-73) cells were arrested by alpha-factor in G1 at 25°C and released in fresh YEPD containing 0.2 M HU at 25°C for 1 hour, at which point almost all the cells showed emergence of tiny buds. The culture was divided into two, one half was kept shaking at 25°C while the other was transferred to 35°C. Cells showing mitotic spindles at 25°C (D) and at 35°C (E) after 2 hours of HU treatment post temperature shift. Flow cytometry data (right panels) shows the progression of scc1-73 cells through S-phase at 25°C and 35°C. DNA contents: Exponential culture (shaded histogram), G1-arrested cells (black line), cells released from G1 arrest at 25°C after 1 hour of 0.2 M HU treatment (black dotted line) and cells treated for additional 2 hours with 0.2 M HU in D and E (red line).