Figure 2.

The appearance of aberrant spindles and of lethality coincide in cut11–1 cells grown at the restrictive temperature. Aliquots of synchronized cells were removed at the times indicated, fixed, and stained for tubulin and DNA (A) or assayed for viability by determining the percent that retained the ability to form colonies on plates incubated at the permissive temperature (B). The fraction of cells with abnormal mitosis is indicated with ▪, and normal mitosis is shown with □ (A). Abnormal mitoses were cells with a spindle morphology similar to that shown in Figure 1. Approximately 300 cells were assayed for each data point. Viability was assessed by the ability to form colonies at the permissive temperature; the means and SD from these trials are indicated (B). The viability of the cells taken immediately from the gradient was defined as 100%. Similar results were obtained for cut11–2.