[A simple method of selecting Saccharomyces cerevisiae ade1 and ade2 mutants].

A simple technique of selection for spontaneous red mutants of yeast Saccharomyces cerevisiae is proposed. It is based on incubation of yeast cells carrying a deletion in the GCN4 gene on a solid selective medium containing 3-amino-1, 2, 4-triazole (3AT). After incubation for three weeks at 30 degrees C, the 3 AT-resistant mutants ade2 and ade1 were easily visualized due to the pink or red colony color; they were then selected and analyzed by genetic and biochemical methods. The frequency of these colored mutants was approximately 10-9. The method proposed is shown to be suitable for selection and analysis of both spontaneous mutants ade2 and ade1 and those induced by various mutagens. The possible molecular mechanism of 3AT-resistance of red mutants is discussed. This mechanism involves GCN4-independent activation of expression of genes of purine and histidine metabolism. This activation results from purine starvation caused by arrest of purine biosynthesis the ade2 and ade2 mutations.