Carcinogens induce intrachromosomal recombination in yeast.

To identify environmental carcinogens there is a need for inexpensive and reliable short-term tests that can be used to predict the carcinogenic potential of any given substance with high accuracy. The Ames assay, which is based on the induction of mutations in Salmonella typhimurium, is the most extensively used short-term test but certain human or animal carcinogens exist that are persistently undetectable as mutagens with the Ames assay or with other short-term tests. There is a need for a short-term test to detect those carcinogens that are missed by the Ames assay. Carcinogenesis is in many cases associated with genome rearrangement. Because of this association a system screening for intrachromosomal recombination that results in genome rearrangement has been constructed for potential use as a short-term test in the yeast Saccharomyces cerevisiae. Evaluation of this recombination system shows that it is readily inducible by a variety of mutagenic as well as non-readily inducible by a variety of mutagenic as well as non-mutagenic carcinogens, including carcinogens that are not detectable by the Ames assay or by various other short-term tests, such as safrole, urethane, ethionine, auramine, methylene chloride, carbon tetrachloride, cadmium sulfate, aniline, dimethylhydrazine, aminotriazole, acetamide, thiourea and DDE. The present report shows the data for these as well as for additional agents, their response profiles with different concentrations of the agents and the protocol for the DEL system.