Figure 1.—

Inducible silencing at HML and HMR. (A) Steady state repression at HML and HMR. Strains YSH505, YSH872, and YSH811 were grown to steady state in media containing raffinose or raffinose with galactose. Levels of α1, a1, and ACT1 mRNA were measured by reverse transcriptase–PCR (RT–PCR). Expression at HML and HMR was normalized to ACT1 and expressed as a ratio relative to the uninduced (no galactose) control. In this and all succeeding figures the cumulative results of at least three independent experiments are shown in the graph, while a representative gel scan from a single experiment is shown. (B) Kinetics of repression at the HMR locus. A culture of strain YSH811 was grown to log phase in YPraffinose media; at time 0, galactose was added to 2%. RNA was collected at the indicated time points and the levels of a1 and ACT1 message were measured by RT–PCR. (C) Kinetics of repression at the HML locus. α1 message was measured from RNA obtained from the same cell cultures described in B.