DNA-mediated gene transfer to baby hamster kidney cells.

Abstract

To establish the conditions for the efficient transfer of foreign genes to baby hamster kidney (BHK) cell lines, we investigated the factors that affect the efficiency of transformation of thymidine kinase deficient (tk^-) BHK cells to the tk⁺ phenotype. Plasmid pAGO, which carries the herpes simplex virus (HSV) tk gene, was used as the donor DNA, and the frequencies of transformation of BHK and mouse L cells under various conditions were compared. Although the optimal times of exposure to DNA were almost the same, the two kinds of cells had different cell density dependencies; transformation of BHK cells occurred only when a limited number of cells were seeded prior to DNA transfer, whereas there was a high frequency of transformation with mouse L cells over a broader range of cell density. The frequency of transformation increased as the amounts of pAGO DNA increased, and a clear dose dependence was found. The efficiency of the transformation for BHK cells was about 80 tk⁺ transformants per 4 × 10⁵ cells per 400 ng of pAGO DNA; about 50 times lower than the efficiency of transformation for mouse Ltk^-cells.