Figure 5.

Real-time PCR measurements of the mRNA expression levels for the same experiment as in Figure 2. (a) Regulatory genes of the GAL system and MIG1, (b) gfp and HIS3, and (c) structural genes of the GAL system and ADH1 control are shown. The mRNA expression levels are normalized by the expression of ACT1. The y-axis is logarithmic. The arrows mark the points of medium switch: galactose to glucose (left arrow), glucose to galactose (middle arrow), and galactose to glucose (right arrow). The gray curve is the OD trace of the population. Note that the regulatory genes (including MIG1) do not follow the same kinetics as the GAL structural genes. Also, after the second transition from galactose to glucose, the mRNA levels are immediately adapted to the new environment.