title: Chemically induced mutagenesis in a shuttle vector with a low-background mutant frequency.
abstract: We have developed a recombinant DNA shuttle vector that permits the molecular analysis of mutations induced in human cells by chemical or physical mutagens. The vector is able to replicate as a plasmid in Escherichia coli and in Epstein-Barr virus (EBV)-transformed human lymphoblastoid cell lines and contains the herpes simplex virus type 1 thymidine kinase gene (HSV tk) as the target for mutagenesis studies. After introduction of the vector into an EBV-transformed lymphoblastoid cell line (LCL-721) by electroporation, approximately equal to 2% of the transfected cells expressed the vector-encoded gene for hygromycin resistance. Plasmid DNA isolated from cells immediately after selection for hygromycin resistance (10 population doublings posttransfection) contained mutations in the HSV tk gene at a frequency of 6 X 10(-5). Treatment of plasmid-bearing LCL-721 cells with N-ethyl-N-nitrosourea resulted in a dose-dependent increase of up to 15-fold in the frequency of mutations in the HSV tk gene. The dose-response for the induction of mutations in the plasmid-encoded gene closely paralleled that for the induction of mutations in the cellular gene for hypoxanthine (guanine) phosphoribosyltransferase.
mesh_terms: D004305:Dose-Response Relationship, Drug; D005038:Ethylnitrosourea / Q000494:pharmacology; D005822:Genetic Vectors; D004854:Herpesvirus 4, Human / Q000235:genetics; D006801:Humans; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics*; D008214:Lymphocytes / Q000187:drug effects; D009152:Mutagenicity Tests / Q000592:standards; D009154:Mutation / Q000187:drug effects*; D013937:Thymidine Kinase / Q000235:genetics*; D014162:Transfection
chemical_list: D007041:Hypoxanthine Phosphoribosyltransferase; D013937:Thymidine Kinase; D005038:Ethylnitrosourea