Karyoduction in Saccharomyces cerevisiae

Abstract

We introduced the nuclei isolated from the respiration-sufficient killer strain of the yeast Saccharomyces cerevisiae into the yeast protoplasts prepared from the respiration-deficient non-killer strain with the aid of polyethylene glycol. The resulting karyoductants were respiration-deficient non-killers. Nuclear staining with ethidi~ bromide or DAPI and tetrad analysis of the k~oductan~ presented evidence that the nuclei introduced into protoplasts were fused to the resident nuclei, leading to stable diploids. This technique termed karyoduction will be useful in the study of nucleo-cytoplasmic relationship in yeast and other organisms. YeastFusion

Isolation of Glucoamylase-non-producing Mutants in the YeastSaccharomyces diastaticus

“…All mutant strains produced greatly diminished glucoamylase acrivity. These mutants were crossed with a wild-type strain YIY 4-3A, and the resulting diploids were subjected to tetrad analysis after sporulation, of which the results are presented in Table III 4 ) with selection for prototrophy. Most of the fusants are expected to be diploids, since, in the fusion conditions used, all six fusants examined were diploids, as estimated by tetrad analysis using a standard diploid strain homozygous for MAT.…”

Genes Required for Transcription ofSTA1encoding an Extracellular Glucoamylase in the YeastSaccharomyces

“…16) Diploid strains homozygous for MATwere constructed by the standard protoplast-fusion method with selection for prototrophy. 17) Cytoplasmic petite strains presumed to lack mitochondrial DNA (rhoO) were derived by growing cells on YEPD plates containing 50 Itg/ml ethidium bromide. 16 ) RNA blot analysis.…”

Mating Signals Control Expression of both Starch Fermentation Genes and a Novel Flocculation GeneFLO8 in the YeastSaccharomyces

“…Diploid strains homozygous for MAT were constructed by the standard protoplast-fusion method 7 ) with selection for prototrophy. Most of the fusants are expected to be diploids, since all of the six fusants examined were estimated to be diploids by tetrad analysis of the hybrids constructed by the crosses between each of the fusants and a standard diploid strain homozygous·for MAT.…”