Classic Techniques for Improvement of Industrial Yeast Strains

The enucleation of yeast cells is of interest for the production (by fusion) of special industrial yeast hybrids, possessing mixed cytoplasms (cybrids) but only one nucleus. Such cybrids could be designed to have a modified phenotype without change of ploidy. However, no methods for the enucleation of yeast cells have yet been reported. In animal cells, enucleation usually uses the cytochalasins [3,10,12,13,14,18,19]. In most cases, either cytochalasin B or D have been used to change the properties of the cytoskeleton in such a way as to give nuclear extrusion and, in a small number of species, enucleation [8]. However, only in the case of some mammalian systems (BSC-1 cells, chicken embryo fibroblasts, mouse L cells and human polymorphonuclear lymphocytes) have larger numbers of enucleated cells (cytoplasts) been obtained [10,12,13,14,19]. Yeast cells of Saccharomyces cerevisiae have many fundamental properties in common with cells of higher organisms [4,15]. In particular, the fact that the structure of tubulin and actin filaments is conserved between animal and yeast cells [5,6], makes it likely that cytochalasins should be effective enucleation agents for yeast. In this work the use of cytochalasin B (in combination with synchronization) for the enucleation of some strains of Saccharomyces cerevisiae is reported.