Figure 1.

Asf1 promotes chromosome replication when RFC function is altered. (A) Growth defects in asf1Δ rfc1-1 cells. Tenfold serial dilutions of exponentially growing yeast strains of the indicated genotypes were plated on rich media for 3 d at 30°C. (B) asf1Δ rfc1-1 cells accumulate with 2N DNA content. The indicated strains were grown to log phase at 30°C and DNA content was measured by flow cytometry. (C) asf1Δ rfc1-1 cells display bipolar spindles and chromosome segregation defects. Mitotic spindles were visualized in exponentially growing cells by immunostaining with anti-tubulin antibodies and nuclei were visualized by DAPI staining. Inset shows chromosome missegregation events visible in ∼1% of asf1Δ rfc1-1 cells. (D) asf1Δ rfc1-1 cells have an increased proportion of incompletely replicated chromosomes. Indicated yeast strains were grown to log phase at 30°C, and their isolated chromosomes were separated by pulse field gel electrophoresis. Total DNA was visualized by ethidium bromide (top), and Chromosome III was visualized by Southern blotting (bottom).