Figure 5.

Anti-Plo1 immunofluorescence localization of Plo1 in cdc and cut mutants. (A) Cut7.24 cells that arrest in mitosis but continue to execute cytokinesis regardless of the mitotic defect still had strong Plo1 staining at the time of this abnormal cytokinesis. Anti-Plo1 immunofluorescence microscopy with HN184 revealed that Plo1 shows strong association with the mitotic SPBs of the early septation mutants: (B) cdc7. A20, (C) cdc11. H1, (D) cdc14.118, (E) cdc15.140. Images of cells in the early stages of spindle formation in the first division after cytokinesis that had been inhibited by incubation at the restrictive temperature are shown. Thus, each of the two nuclei had two SPBs that stained with Plo1 antibodies. Plo1 did not localize in (F) cdc25.22 (long cell in A) or (G) cdc2.33 mutant cells after incubation of the temperature-sensitive mutants for 4 h at the restrictive temperature. Wild-type cells (small cell in F) were mixed with cdc25.22 cells to show that the lack of Plo1 staining was not due to a technical problem. Because the smaller wild-type cells stained normally, we conclude that there was no association of Plo1 with the SPB.