The Induction of DNA Double-strand Breaks in CHO Cells by Pvu II: Kinetics Using Neutral Filter Elution (pH 9·6)

Summary

Chinese hamster CHO K1 cells were treated with the restriction endonuclease Pvu II during electroporation and assayed for DNA double-strand breaks (dsb). Dsb were measured by the non-denaturing filter elution technique (pH 9·6) at various times up to 24 h after restriction endonuclease (RE) treatment. The frequency of dsb following electroporation in the presence of 200 units/ml Pvu II increased over the post-treatment incubation period. This was found not to be due to cell or DNA degradation, indicating that Pvu II remains active for at least 24 h inside the cell. We suggest that these kinetics of dsb result from a competition between incision (by Pvu II) and dsb repair.