Figure 5

Decrease in mitotic spindle stability and irregular distribution of mitotic spindles. (a) The rate of microtubule polymerization was quantified by measuring α-tubulin fluorescence intensity at indicated time points after releasing from nocodazole arrest. A representative data from three independent experiments are shown as mean±s.d. *P<0.05,**P<0.005 by Student’s t-test (n=8; left panel). The basal level of spindle intensity from MG132-arrested metaphase cells was measured. A representative data from three independent experiments are shown as mean±s.d. *P<0.05 by Student’s t-test (n=80; right panel). (b) After cold treatment for 10 min, remained microtubules on kinetochores were observed (left panel) and its intensity was measured (right panel). Insets in the left panel show enlarged view (indicated by the boxed regions) of optical sections showing individual kinetochore. A representative data from three independent experiments are shown as mean±s.d. **P<0.005 by Student’s t-test (n=124). Scale bar, 5 μm. (c) The line-scan profiles of microtubules attached to chromosomes on metaphase plate were visualized, and the intensity of mitotic spindles was measured in white box. **P<0.005 by Student’s t-test (n=8). Scale bar, 5 μm. (d) The scarcity of microtubule intensity in the central region of metaphase plate. The length of white box in c was divided into three. Microtubule intensity in central one-third was measured, and divided by the microtubule intensity of entire white box. **P<0.005 by Student’s t-test (n=8).