TABLE 1.

pol30 mutants are defective in silencing

Gal4-Sir1p	Relative efficiency of a1 mRNA expressiona
	POL30	pol30-8	pol30-6	pol30-79
−	1	1	1	1
+	0.053 ± 0.036	0.096 ± 0.0022	0.36 ± 0.066	0.17 ± 0.015

^a Silencing at HMR was monitored in logarithmic POL30 and pol30 cells. For each strain, the relative level of a1 mRNA was calculated as the ratio of PhosphorImager units as follows: [(a1/SCR1 in the absence or presence of Gal4-Sir1p)/(a1/SCR1 in the absence of Gal4-Sir1p)]. The data have been normalized to the ratios observed in the absence of Gal4-Sir1p to combine data from independent experiments: mean ± S.D., n = 3.