Figure 5.

Effect of a resident ecoRVC on the establishment of an incoming EcoRV RM system. Cells carrying pYNEC126 (ecoRVC⁺) or pYNEC130 (ecoRVC⁻) were transformed with 150 ng of pYNEC113 (R⁺ M⁺ C⁺), pYNEC117 (R⁻ M⁺ C⁺), pYNEC118 (R⁺ M⁺ C⁻), or pBR322 (vector). Each DNA solution contained 100 ng of pKC31 (Km^R) as an internal control of the transformation efficiency. For each assay, the number of Ap^R transformants was divided by the number of Km^R transformants. The relative transformation efficiencies are the above ratios further divided by the ratio for pBR322. The measurements were carried out in duplicate in two separate experiments.