FIG. 7.

Effect of vhs expression on the in vivo stability of PDA1 mRNA. Strains W303 pYEX-BX (empty vector) and W303 pYEX-BX vhs (vhs) were grown to an OD₆₀₀ of 0.6 in YNBD, and a 10-ml aliquot was withdrawn for RNA extraction (solid arrow). The remainder of the culture was induced with the addition of 0.5 mM CuSO₄ for 30 min. Another aliquot was then removed for RNA extraction (open arrow), and transcription was inhibited in the remainder of the culture with 100 μg of phenanthroline per ml. Aliquots were then removed every 30 min over a 3-h time course. Total RNA was analyzed for PDA1 mRNA levels by Northern blot hybridization. Lane 1, RNA extracted just before induction with CuSO₄; lane 2, RNA extracted just before addition of phenanthroline; lanes 3, 4, 5, 6, 7, and 8, RNA extracted at 30, 60, 90, 120, 180, and 210 min after addition of phenanthroline, respectively.