FIG. 2.

RNAi is effective in growing, starved, and mating cells. (A) Induction and persistence of RNAi in SERH3 hairpin transformants. RNA was taken from SERH3hp cells at indicated times after the addition of CdCl₂ (1.0 μg/ml in growing cells, 0.1 μg/ml in starved cells). Starved cells induced for 4 hours were washed to remove Cd and resuspended in growth medium; samples were then harvested at 2, 4, and 24 h after refeeding. Northern blots were hybridized with SERH3 probes to determine degree of mRNA degradation, and RPL21 was used as a loading control. The arrow indicates the SERH3 mRNA degradation product. (B) Constitutively expressed and mating-specific genes can be silenced during mating, and mating of two different hairpin-expressing strains results in silencing of both targeted genes in the paired cells. Mating cells of the indicated genotypes were left untreated (−) or were treated with 0.05 μg/ml CdCl₂ for 2 hours prior to mating (+), and RNA was prepared from cells at 4 h after the initiation of mating. Northern blots were hybridized with the probes indicated to the left of each panel, CNJB was used as loading control specific to mating cells, and other loading controls (LC) are indicated (36).