Open AccessIsolation and characterization of mutants of human diploid fibroblasts resistant to diphtheria toxin.
Author(s) -
Radhey S. Gupta,
Louis Siminovitch
Publication year - 1978
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.75.7.3337
Subject(s) - diphtheria toxin , mutant , mutagenesis , biology , mutation , corynebacterium diphtheriae , microbiology and biotechnology , fibroblast , ploidy , toxin , mutation frequency , cell culture , genetics , diphtheria , virology , gene , vaccination
Stable mutants highly resistant to the protein synthesis inhibitor diphtheria toxin (dipr) have been selected in human diploid fibroblast cells at a frequency of 1-8 X 10(-6). Treatment of cells with mutagens, (e.g., ethylmethanesulfonate, nitrosoguanidine, and ICR-170), increased the frequencies of dipr mutants by 50- to 500-fold in different experiments, and the optimal expression time for dipr mutation was about 5 days. All mutants examined thus far have bred true, and no effects of cell density or cross feeding have been observed on the selection. Fluctuation analysis showed that the dipr mutation occurs in these fibroblasts at the rate of 5-6 X 10(-7) mutations per cell per generation. Protein synthesis in mutant extracts was resistant to diphtheria toxin, indicating that the dipr lesion in such mutants lies in the protein synthesis machinery. The characteristics of the dipr marker should make this system particularly useful for studies of quantitative mutagenesis in human diploid cells.