Figure 2

Comparison of the performance of helper plasmids in enabling I-SceI cleavage of a target site. Individual colonies of E. coli K-12 MG1655 cells containing the helper plasmid and into which a mutation cassette designed to introduce a C-terminal 3xFLAG tag on RpoD had been integrated were spread on agar plates containing LB Miller medium and 100 μg/mL ampicillin. Plates on the right half of each set contained 100 ng/ml anhydrotetracycline to induce expression of I-SceI. Successful cleavage of the mutation cassette results in a diminution of the number of viable colonies.