title: Quantitative comparative mutagenesis in bacteria, mammalian cells, and animal-mediated assays. A convenient way of estimating genotoxic activity in vivo?
abstract: The accumulation of environmental compounds which exhibit genotoxic properties in short-term assays and the increasing lag of time for obtaining confirmation or not in long-term animal mutagenicity and carcinogenicity tests, makes it necessary to develop alternative, rapid methodologies for estimating genotoxic activity in vivo. In the experimental approach used here, it was assumed that the genotoxic activity of foreign compounds in animals, and ultimately humans, is determined among others by exposure level, organ distribution of (DNA) dose, and genotoxic potency per unit of dose, and that knowledge about these 3 parameters may allow to rapidly determine the expected degree of genotoxicity in various organs of exposed animals. In view of the high degree of qualitative correlation between mutagenic activity of chemicals in bacteria and in cultured mammalian cells, and their mutagenic and carcinogenic properties in animals, and in order to be able to distinguish whether mutagenic potency differences were due to differences in (DNA) dose rather than other physiological factors, the results of mutagenicity tests obtained in the present experiments using bacteria and mammalian cells were compared on the basis of DNA dose rather than exposure concentrations, with the following questions in mind: Is there an absolute or a relative correlation between the mutagenic potencies of various ethylating agents in bacteria (E. coli K12) and in mammalian cells (V79 Chinese hamster) after treatment in standardized experiments, and can specific DNA adducts be made responsible for mutagenicity? Is the order of mutagenic potency of various ethylating agents observed in bacteria in vitro representative of the ranking of mutagenic potency found in vivo? Since the answer to this last question was negative, a further question addressed to was whether short-term in vivo assays could be developed for a rapid determination of the presence (and persistence) of genotoxic factors in various organs of mice treated with chemicals. In quantitative comparative mutagenesis experiments using E. coli K12 and Chinese hamster cells treated under standardized conditions in vitro with 5 ethylating agents, there was no indication of an absolute correlation between the number of induced mutants per unit of dose in the bacteria and the mammalian cells. The ranking of mutagenic potency was, however, identical in bacteria and mammalian cells, namely, ENNG greater than ENU greater than or equal to DES greater than DEN congruent to EMS, the mutagenic activity of DEN being dependent on the presence of mammalian liver preparations.(ABSTRACT TRUNCATED AT 400 WORDS)
mesh_terms: D000477:Alkylating Agents / Q000633:toxicity*; D000818:Animals; D001419:Bacteria / Q000235:genetics*; D001711:Biotransformation; D002478:Cells, Cultured / Q000187:drug effects*; D006224:Cricetinae; D003412:Cricetulus; D004260:DNA Repair; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000187:drug effects; D005260:Female; D009152:Mutagenicity Tests; D010053:Ovary
chemical_list: D000477:Alkylating Agents