Fig. 1. Spindle formation and chromosome segregation defects upon overproduction of Xenopus Aurora A in S. pombe. Panels A and B show immunofluorescence/DAPI staining. The first panel in each series bears the label and shows microtubules, the next spindle poles, while the last one shows a combined DAPI and DIC image. Expression of Eg2 induces defects in chromosome segregation (A) and spindle formation (B). Wild-type cells bearing a pREP3XEg2 plasmid were grown at 30°C so that 20 hours after induction they would be in mid-log phase and samples were fixed every 2 hours from 14-22 hours later. The three mitotic cells in A are clearly unable to segregate their chromosomes. The microtubules in B emanating from a single focus of Sad1 staining indicates that spindle formation is defective. (C) Quantitation of the phenotypes arising from expression of Xenopus aurora A. The graph shows the frequency with which each particular mitotic defect is seen in an entire population of cells. Open squares, monopolar spindles; open circles, chromatin stretched along an anaphase spindle; triangles, ‘cut’ phenotype; green diamonds cells with bi-polar spindles and condensed chromatin; filled squares, diploid cells with large amorphous nuclei.
