Figure 1.

Northern analysis of stable RNA species from wild-type and mutant E. coli strains. Total RNA from each strain was isolated, and high-resolution Northern blotting was performed as described in Experimental Procedures. PAP activities were measured for all of the cells. No detectable activity was seen in the PAP⁻ strain, and two- to-threefold elevation of activity was seen in the pJL89-containing strains. M shows the position of the mature RNA species. The length of the precursor residues was determined by running a DNA sequencing ladder side-by-side (7–9).