Open AccessUltraviolet light induction of diphtheria toxin-resistant mutants of normal and xeroderma pigmentosum human fibroblasts.
Author(s) -
Thomas W. Glover,
ChiaCheng Chang,
James E. Trosko,
Steven S. L. Li
Publication year - 1979
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.76.8.3982
Subject(s) - xeroderma pigmentosum , diphtheria toxin , mutant , mutation , biology , microbiology and biotechnology , ultraviolet light , mutagen , strain (injury) , toxin , chemistry , genetics , dna repair , gene , dna , photochemistry , anatomy
The UV induction of diphtheria toxin-resistant (DTr) mutants in normal and xeroderma pigmentosum human fibroblasts has been quantitatively characterized. A concentration of diphtheria toxin at which DTr cells are cross-resistant to Pseudomonas aeruginosa exotoxin A was determined and used in the selection of resistant mutants. Recovery of mutants was not influenced by the presence of wild-type cell densities of 1-8 x 10(5) per 9-cm plate, indicating no metabolic cooperation exists, in contrast to what is seen in the selection of some other variant phenotypes. Expression periods for UV-induced mutations differed with the severity of mutagen treatment and cell strain used. A relatively long (10-15 days after UV treatment) expression period was required for the maximum recovery of DTr mutants. Maximum recovery was followed by a decrease in mutation frequency on subsequent days evaluated. An apparent linear dose response within the dose range used was observed for UV-induced mutations in both normal and xeroderma pigmentosum fibroblasts. Our results indicate that xeroderma pigmentosum fibroblasts have higher UV-induced mutation frequencies per unit UV dose but similar frequencies per unit survival compared to normal cells within the range of UV doses tested.