TABLE 3.

Temperature-sensitive silencing mediated by conditional SIR2 alleles

	% α-factor arrested
SIR2 allele	23°	37°
SIR2	91	96
sir3-8	96	1
sir2-604	96	2
sir2-614	98	2
sir2-620	96	0

Yeast strains bearing different SIR2 alleles were grown to log phase at 23° or 37° and then challenged with 10 μg/ml α-factor. The percentage of unbudded (G₁ blocked) cells after 5 hr incubation in α-factor is listed. A strain bearing the temperature-sensitive sir3-8 allele was assayed as a control. A minimum of 200 cells was assayed for each determination.