Polymerization of vector DNA after transfection into hamster fibroblast cells.

We have transformed hamsters lung fibroblasts with two cloned, selectable markers, the widely used pSV2gpt vector and pNEO3, which confers resistance to neomycin. Analysis of DNA extracted from both individual and pooled groups of several hundred transformants reveal that in these carrier DNA-free transformation experiments, the vector DNA are found in concatenate forms in the transformants. The copy number of the integrated vectors can vary from a few to several hundred. In addition, the efficiency of transformation is ten times higher in the case of pSV2gpt.