Figure 4.

Overexpression of NDC1–3xpk causes cells to arrest and increase in ploidy. Asynchronous cultures of yeast cells containing GAL-NDC1–3xpk integrated at the LEU2 chromosomal locus [HC14–10c(1235); see Table 1] were arrested in G₁ by using α-factor for 2.5 hr. The culture then was split; one half was resuspended in medium containing α-factor with glucose (Uninduced), and the other half was resuspended in medium containing α-factor with galactose (Induced) for an additional 1.5 hr to induce the expression of NDC1–3xpk in the induced culture. The cells then were rinsed and resuspended in either glucose-containing (Uninduced) or galactose-containing (Induced) medium to release them from the α-factor block. Samples were taken for flow cytometry, budding index analysis, and viability every hour for 5 hr. (A) Flow cytometric profiles of uninduced and induced cultures. (B) A graph showing the percentages of large-budded cells and higher ploidy surviving cells, either diploid or mixed ploidy, at selected time points.