FIG. 4.

Pheromone gene expression in Δbpp1-2 strains. We loaded 15 μg of total RNA per lane and subjected it to Northern analysis. The same filter was hybridized in succession with probes for mfa1 and cbx or rRNA as loading controls. (A) Strains and strain mixtures, indicated at the top, were grown on charcoal-containing CM plates for 48 h. (B) The FB1Δbpp1-2 deletion mutant was grown in liquid PD medium without and with cAMP at the concentrations indicated. (C) Epistatic relationship of bpp1 and ubc1. Strains were grown on charcoal-containing CM plates for 48 h. (D) Mating reactions of bpp1 deletion strains on PD-charcoal plates supplemented with 6 mM cAMP. Dikaryon formation can be observed as white fuzzy filaments. The strain combinations indicated were spotted alone or in combination and incubated for 48 h at 28°C.