Fig. (1) Electrophoretic mobility of representative plasmid DNA isolated from overnight cultures. Plasmid DNA isolated from E. coli transformants using the rapid boiling method  was fractionated on an agarose gel. Because the samples were not treated with RNaseA, RNA appeared at the bottom of the gel. Horizontal arrowheads (<) indicate the plasmid DNA showing size alteration. (A) pAL79 DNA isolated from JM107 transformants. Lane 1, sample containing normal pAL79 plasmid; lane 2, sample containing altered plasmid; lane M, HindIII-digested λphage DNA size markers. SC, supercoiled molecule; OC, open circle (relaxed molecule); SCD, supercoiled dimer molecule. (B) pAL79 DNA isolated from DH10B transformants. Each lane corresponds to a DNA sample isolated from an independent colony. The vertical arrow indicates the sample containing the altered plasmid DNA. Lane M, HindIII-digested λ phage DNA size markers. (C) pUC19 DNA isolated from DH10B transformants. Lane 1, sample containing normal pUC19 plasmid; lane 2, sample containing altered plasmid; lane M, HindIII-digested λ phage DNA size markers.