FIG. 5.

Regulation of HM silencing by NAM and PNC1. (A) Mating assay to measure the silencing of the HMR and HML loci in general. WT (DSY50), pnc1Δ (DSY46), and npt1Δ (DSY75) strains were mated to a MATa tester strain (SY35) in the presence of 0, 2.5, or 5 mM NAM for 4 h. Fivefold serial dilutions of cells were spotted. Growth of the resulting diploids on SD plates is indicative of silencing. The MATa tester strain was spotted as a negative control. (B) Silencing at HMR was measured by using WT or sir2Δ versions of a hmrΔA::TRP1 reporter strain that were transformed with either a pRS425 empty vector or the high-copy-number PNC1 vector, pJOE31.