FIG. 5.

Expression of SMK1 mRNA by mse^S and urs1^S promoter mutants during sporulation. Diploid yeast containing a single integrated copy of wild-type SMK1 coding information under the control of the indicated mutant promoter was transferred to sporulation medium, and total RNA was prepared from cells harvested at the indicated times and assayed by Northern blot hybridization. The indicated smk1 promoter mutants were generated using the following integrating plasmids, from left to right: wild-type (pMDP199), pseudo-urs1^S (pMDP183), mse^S (pMDP185), and pseudo-urs1^S mse^S (pMDP187) (see Table 2). The same filter was probed with sequences specific for the SPO12 middle gene, the HOP1 early gene, and the pC4/2 constitutive expression control.