The Ames test for potential mutagenicity of chemical compounds

Example Experiment 59 extract ' 59 extract 0 $9 extract is added to mutant strains of his‘ S. typhimurium. o hir1 is a base-substitution his-1 his—2 mutant, his— 2 is a frameshift base substitution frameshift mutant. mutant mutant 9 The S9—bacterial mixture from each strain is spread on one Test Test experimental plate and one compound compound control plate. 0 A paper disk is put on each plate. P35? The test compound is added to the experimental plate disk but not to control-plate disks. 9 The presence of a significant number of revertant colonies indicates the test compound Experimental Control Control Experimental induces base—substitution plate1 plate 1 plate 2 plate 2 mutations. I I l l G The control plates determine Example experiment results the rate of spontaneous o 1 his— -> his' reversion. " 0 An insignificant number of revertant colonies indicates the test compound does not induce frameshift mutations. A significant Few, if any, Few, if any, number spontaneous revertant of revertant revertant colonies colonies colonies