FIG. 2.
Southern hybridization analysis of candidate Δalr mutants. SmaI digests of genomic DNA were probed with the radiolabeled left flank probe of the deletion construct (Fig. 1). Strains that are wild type at the alr locus are predicted to have doublet bands in the 1.5-kb region, while Δalr strains should have a single band in this region. The lower portion is a longer exposure of the same blot to allow detection of the 0.6-kb band detected in all strains except wild-type mc2155. Molecular masses of size markers are indicated in kilobases. The phenotypes of strains DM21 to DM26 are shown in Table 2.