FIG. 4.

ydeA mRNA levels in wild-type and mutant strains. For each strain, two independent cultures were grown at 37°C to an A₆₀₀ of 0.4 in NZ medium, and total RNA was isolated. (A) Two micrograms of RNA was hybridized to a ³²P-labeled ydeA cRNA probe (450 nt). After digestion with pancreatic RNase, the hybrids were denatured and electrophoresed in a 5% polyacrylamide gel. The protected fragment is 360 nt long (arrow); traces of undigested probe are visible in the upper portion of the gel. The wild-type (wt) strain was SB0. (B) Two cultures of DB530 (ydeA⁺) and DB529 (SB1 derivative) grown in LB medium were induced for 20 min with 2% arabinose (+) or not induced (−). Ten micrograms of RNA was hybridized to detect the very low levels of ydeA mRNA in wild-type cells. The gel was exposed for 4 days (wild type) and 20 h (SB1).