[A new system of selecting yeast mutants with disrupted genetic recombination processes]

A new convenient system for isolation of the yeast mutants deficient in the genetical recombination is proposed. The chimeric plasmids constructed to carry the noncomplimenting mutant copy of the yeast ADE2 gene and different selectable yeast markers (LEU2 or TRP1 genes) are the basis for the system. Interplasmid intragenic recombination of ADE2 gene alleles in yeast cells transformed by two chimeric plasmids results in appearance of the secondary white prototrophic clones covering the primary red colony. The number of the clones reflects the recombination processes and is subject to an easy visual control. The proposed technique allows one to reveal both hypo and hyperrecombination mutants. Crossover or the gene conversion events can be distinguished by the simple genetical analysis of the secondary clones. The collection of mutants deficient in the genetical recombination has been obtained by the proposed technique.