Effect of Potassium versus Sodium in the Sporulation of Saccharomyces.

Adamis (1949, 1950) described a modified Stantial (1935) acetate medium consisting of low concentrations of glucose, so(lium acetate, and agar upon which he obtained high yields of asei with a large number of yeast cultures. Although, in his original experiments, Adams (1949) tested a variety of acetate salts, including potassium acetate, he found none of them superior to sodium acetate in about 0.24 per cent concentration. These reports have been followed by a rather extensive series of papers in which Adams' sodium acetate medium has been used with only slight mo(lificatioiis. These include the hybridization and genetic studies of Fowell (1952, 1955) and the extensive studies of physiological factors affecting yeast sporulation on soditum acetate medium of Adams and Miller (1954); Miller et al. (1957a, b); Scheiber et al. (1957); Tremaine and Miller (1954, 1956); 'Miller and Halpern (1956); and Miller (1957). The sodium acetate medium has also proved very useful in cytological studies of McClary et al. (1957a, b) and of Hashimoto et al. (1958). Although many Lindegren cultures of Saccharomyces sporulated abundantly on sodium acetate-yeast extract-glucose medium, others produced asci so rarely that they could not be used in genetic studies. The evolution of the Lindegren breedling stocks are described in the papers of Lindegren and Lindegren (1943a, b). They determine(l that genetic analysis depended upon the isolatioin of haploid strains which did not produce spores unless mated to other haploid strains of complementary mating type. Continued selection of cultures resuilted in a breeding stock with this characteristic, although early in the pedigree, sporulation among single ascospore segregants was not too unusual. It was presumed that much of this was due to illegitimate copulation producing illegitimate d1iploids, but some of the