FIG 4.

Transcript levels of mating genes under mating and exponential growth conditions. For transcript level analysis, cells were first grown in rich (YPD) medium to analyze gene expression during exponential growth and then shifted to nitrogen-free mating medium to induce mating gene expression. Transcript levels were normalized to ACT1 expression. The error bars represent the standard deviations of three biological replicates. Student's t test showed significant differences in gene expression between the mating types and culture conditions (P < 0.05) (for details, see Tables S1 and S2 in the supplemental material). (A) MAT gene expression in dic1-2Δ(α) and dic1-2Δ(a) cells is induced under mating conditions in a mating-type-specific manner. (B) Mating-type-specific pheromone surface receptor gene expression in dic1-2Δ(α) and dic1-2Δ(a) cells. (C) Increased levels of all 4 MAT transcripts were detected in cultures of homothallic K. phaffii wild-type cells under mating conditions. (D) Induction of pheromone surface receptor gene expression in homothallic K. phaffii wild-type cells under mating conditions.