title: A defined medium for and the effect of insulin on the growth, amino acid transport, and morphology of Chinese hamster ovary cells, CHO-K1 (CCL 61) and the isolation of insulin "independent" mutants.
abstract: Insulin, FeSO4, or transferrin are major requirements together with HEPES buffer and selenium for the growth of CHO-K1 (CCL 61) in a modified F12 medium (M-F12). Insulin stimulates growth at 1 ng/ml to 10 micrograms/ml. In the defined medium minus insulin, CHO-K1 grows slowly as elongated, elliptical cells in parallel arrays typical of normal diploid fibroblasts in contrast to round-to-cuboid cells in loosely overlapping arrays in the presence of serum or insulin. During prolonged incubation in the absence of insulin the cells gather up into a large spherical cluster of viable cells. Insulin "independent" mutants have been isolated whose growth rate during exponential phase in the absence of insulin (48 h to 84 or 96 hrs) is 2.7 to 3.6 times that of the parental culture. Insulin stimulates the growth of these variants only during the first 48 h and is inhibitory at 50 to 500 ng/ml during the exponential phase. Insulin induction of the A system of amino acid transport occurs in about 8 h and requires both protein and RNA synthesis.
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D006224:Cricetinae; D003470:Culture Media; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D007328:Insulin / Q000494:pharmacology*; D009154:Mutation; D010053:Ovary / Q000166:cytology
chemical_list: D000596:Amino Acids; D003470:Culture Media; D007328:Insulin; D003609:Dactinomycin; D003513:Cycloheximide