Mutagen testing of agricultural chemicals with yeast

The microorganism Saccharomyces cerevisiae is frequently used to test chemical agents in short-term mutagenicity tests. Advantages of yeast are its eukaryotic character and the numerous genetic endpoints which can be tested. A disadvantage is the lower sensitivity towards compounds which, when compared with the Salmonella Ames test, need to be metabolized in order to be active. However, the sensitivity of yeast tests can be improved by using cells from the logarithmic phase and by growing them under conditions which increase the activity of metabolizing enzymes, such as the cytochrome P-448/P-450 complexes. Furthermore, we discuss which information can be drawn from the shape of the survival and mutation frequency curves, and which parameters from the mutant yield curves can be used to compare the mutagenic efficiencies of various agents or the mutabilities of various test systems. Also, the qualitative yeast assay results are compiled for insecticides and herbicides in agricultural usage in Third World countries (Pakistan, for example).