FIG. 1.

Southern hybridization analysis of areAΔ2-389 transformants. Genomic DNA from the wild type (lanes 1 and 8) and six transformants (lanes 2 to 7 and 9 to 14) was digested with either XhoI (lanes 1 to 7) or KpnI (lanes 8 to 14), electrophoresed on a 0.8% (wt/vol) agarose gel, blotted, and probed with the transforming DNA. The expected sizes of the restriction fragments are given (in base pairs) to the left of the gel. An 82-bp XhoI fragment, present in the wild type but deleted from the transformants, has presumably migrated off the gel and is not visible. The banding pattern is fully consistent with all six transformants having a single copy of the transforming DNA integrated homologously at areA.