Fig. 1.

Mitosis is impaired in the dbf-2 mutant. In contrast to the round nuclear morphology in the wt and ku-70 control strains, the dbf-2 mutant nuclei are elongated, as determined by DAPI staining of hyphae (top panels). Round nuclei are also observed in conidia of the wt (middle panels; fluorescence and fluorescence with bright field, respectively), whereas nuclei in constricted proconidial chains of the dbf-2 strain are elongated. Scale bars represent 50 μm (wt and dbf-2 strains), 25 μm (ku-70 strain), and 10 μm (middle panels). The prevalence of elongated nuclei in the different strains is shown (bottom left panel). Data shown are based on the averages of three experiments, in which nuclei in 10 fields (of each strain) were counted. Bars indicate standard errors. DBF-2::GFP expressed in the nucleus of a pED4 dbf-2 transformant (G10) fully complements the dbf-2 mutant phenotype (bottom right panel).