All strains carry the reporter plasmid pKB852 (P_IME2-CYC1-lacZ-URA3) and the indicated strains carry pTL5 (P_ACT1-IME1-TRP1), which can complement the sporulation defect of an ime1Δ/ime1Δ diploid. Cells were grown for 2 days in selective media containing 0.5% glucose. Mitotic cultures were collected at this time, and the remaining culture shifted to SPO. After 1 hr in SPO, the culture was divided and one-half was brought to 40 mM HU, while the other remained untreated. These samples were cultured an additional 23 hr and then collected. The β-galactosidase activity (Miller units) of three independent cultures were all within 22% of the presented average value.