FIG. 5.

ste11⁺-regulated genes are derepressed in Δnrd1 cells and repressed by nrd1⁺ overexpression. (A) Expression of ste11⁺, mei2⁺, rep1⁺, and sxa2⁺ mRNA during glucose reduction. The homothallic h⁹⁰ nrd1⁺ or h⁹⁰ Δnrd1 cells were grown in PM medium to mid-log phase and then incubated for the indicated times in PM medium containing 0.5% glucose, and cellular RNA was prepared. Total RNA (20 μg each) was applied to each lane and analyzed by Northern blotting. (B) Expression of ste11⁺, mei2⁺, and sxa2⁺ mRNA in heterothallic cells during glucose reduction in the presence of P-factor. Exponentially growing h⁻ nrd1⁺ and h⁻ Δnrd1 cells were incubated for the indicated times in complete PM medium or PM medium with 0.5% glucose, both containing 2 μg of synthetic P-factor per ml. Total RNA was prepared and analyzed by Northern blotting. (C) Inhibition of mei2⁺ induction by overexpression of nrd1⁺. Exponentially growing h⁻ leu1-32 cells harboring pALSK or pALSKnrd1⁺ were incubated for the indicated times in PM medium containing 0.5% glucose. The level of mei2⁺ transcript was analyzed by Northern blotting. Et-Br, ethidium bromide.