FIG. 1.

SGS1 is not required for transcriptional silencing of Ty1his3AI-236r in rDNA. Total RNA samples from strains JC236 and JC242 and sgs1Δ and ubc2Δ derivatives were analyzed by Northern blotting. The blot was hybridized to a ³²P-labeled sense-strand HIS3 riboprobe to detect Ty1his3AI RNA (top), an antisense Ty1 riboprobe to detect total Ty1 RNA (middle), and an antisense PYK1 riboprobe as a loading control (bottom). The ratios of Ty1his3AI-236 to PYK1 RNA, normalized to the SGS1 strain (lane 1), were 13.3 (ubc2Δ; lane 2) and 2.0 (sgs1Δ; lane 3); the Ty1his3AI-242/PYK1 RNA ratios, normalized to SGS1 (lane 4), were 1.1 (ubc2Δ; lane 5) and 1.5 (sgs1Δ; lane 6); the Ty1/PYK1 RNA ratios, normalized to SGS1 (lane 1), were 1.5 (ubc2Δ; lane 2) and 1.7 (sgs1Δ; lane 3); and the Ty1/PYK1 RNA ratios, normalized to SGS1 (lane 4), were 1.5 (ubc2Δ; lane 5) and 1.7 (sgs1Δ; lane 6).