title: The isolation and preliminary characterisation of 6-thioguanine-resistant mutants of human diploid fibroblasts.
abstract: Mutant clones of human diploid fibroblasts deficient in the enzyme, hypoxanthine-guanine phosphoribosyl transferase (HGPRT) were selected by their ability to grow in medium containing the cytotoxic purine analogue, 6-thioguanine (6TG). The optimal condtions for mutant selection were 6TG concentrations between 1 and 5 mug ml1 and cell plating densities approximately 10(3) cells cm-2. Nine spontaneous and four radiation-induced 6TG-resistant mutants had less than 2% of the parental strain HGPRT activity and were unable to grow in medium containing azaserine. These mutants were phenotypically stable during greater than 25 population doublings in non-selective medium and five mutants that were examined showed no gross change from the normal human karyotype. Evidence is presented to show that 6TG is a better selective agent than 8-aza-guanine (8AG) for HGPRT-deficient mutants of human diploid fibroblasts.
mesh_terms: D002999:Clone Cells; D004171:Diploidy; D004351:Drug Resistance; D005347:Fibroblasts; D006801:Humans; D007041:Hypoxanthine Phosphoribosyltransferase / Q000378:metabolism*; D009154:Mutation; D013866:Thioguanine / Q000494:pharmacology*
chemical_list: D007041:Hypoxanthine Phosphoribosyltransferase; D013866:Thioguanine