FIG 3.

T. delbrueckii kos3Δ mutants completely lacked silencing at HMRa. (A) HMRa1 expression in the wild type and four S. cerevisiae silencing mutants: sir1Δ, sir2Δ, sir3Δ, and sir4Δ. Expression was measured from deep sequencing of mRNAs and quantified as FPKM. a1 derepression measured in a population of sir1Δ cells was ∼50% that of the derepression measured in sir2Δ, sir3Δ, and sir4Δ mutants, which completely lack the ability to silence HML and HMR. P values: *, <0.01 to 0.05; **, 0.001 to 0.01; ***, <0.001 (Student's t test). The error bars indicate standard deviations. (B) Chromosome V HMRa1 expression in T. delbrueckii in wild-type, kos3Δ, sir2Δ, and sir4Δ strains. In contrast to the more modest effect seen in the sir1Δ mutant, kos3Δ mutants exhibited as great a silencing defect as sir2Δ or sir4Δ mutants.