抄録
Copper resistant strains were obtained by training haploid strains of Saccharomyces cerevisiaethrough repeated subcultures in copper-containing media. Tetrad analysis made after mating one of those resistant strains by a sensitive haploid revealed that the resistance was controlled by a dominant gene which segregated independent of mating type, galactose fermentability and growth type.
From a copper culture of a sensitive diploid strain, resistant clones having a genotype Rr and those having a lower level of resistance were obtained. The genotype of the latter was such as representable by R'r. By genetical analyses of resistant cells isolated from a copper culture inoculated by R'r cells, it was conjectured that R, R' and r are multiple alleles, and that the mutation rate from R' to R is much higher than that from r to R' and from r to R.
