Figure 4.

Phenotypic Analysis of skp1 Temperature-Sensitive Mutants

(A) Shown are G1 arrest (at nonpermissive temperature) of skp1-3 cells and G2/M accumulation (at permissive temperature) and G2/M arrest (at nonpermissive temperature) of skp1-4 cells, as analyzed by flow cytometry (Gerring et al. 1990). The number of cells is depicted on the vertical axis, with fluorescent intensity of emitted light (proportional to DNA content) on the horizontal axis. Logarithmically growing cultures at 25°C were split and incubated at either 25°C or 37°C for 3 hr prior to analysis.

(B) Terminal arrest morphologies of skp1-3 or skp1-4 cells after 3 or 6 hr at 37°C. Cells were stained with 4′,6-diamidino-2-phenylindole and photographed for fluorescence staining and by phase contrast. The fields shown were chosen to emphasize specific phenotypes and are not necessarily representative of overall frequencies.