Figure 2.

Example of analysis of the long bands. Twenty-six long bands of 1,500 bp corresponding to 26 independent Mtx^r colonies obtained by transformation of a hexA⁻ strain with cloned HetII were digested with AflII, NdeI, HindIII, and ClaI separately, and then the products migrated simultaneously on the same agarose gel. On hetII, AflII and HindIII are located 3′ to the deletion, whereas ClaI and NdeI are located 5′ to the deletion. Uncut band and digestion-product lengths are indicated in bp. The sample introduced in lanes r, resistant to the four enzymes, is likely to correspond to a spontaneous Mtx^r mutant. Other bands are sensitive to just one enzyme—e.g., lanes w indicate a band sensitive only to AflII.