Figure 7.

The mode of microtubule–kinetochore association in topo II–defective cells. (A–D) Kinetochore localization of Mad2 and Bub1 in topo II–deficient cells. Cells treated as indicated were fixed with paraformaldehyde and immunostained by anti-Mad2 (A and B) or anti-Bub1 (C and D) antibodies. Transfected cells were harvested after 48 h with or without an additional incubation for 2 h in the presence of ICRF-193. In each treatment, Mad2 and Bub1 were confirmed to localize in prometaphase or prophase chromosomes, respectively. Bar, 10 μm. (E) Based on movie data, the distances between discernible sister kinetochores were measured and plotted on the graph. Data obtained from nocodazole-treated cells served as the control where no spindle and tension existed. (F) The average distances between discernible sister kinetochores during the metaphase-like stage are shown. The value of buffer-transfected control (buffer 1; 1.45 μm) was set to 100%.