Abstract
This chapter describes methods in sporulation and germination of yeasts. Sporulation of yeasts such as Saccharomyces cerevisiae and Schizosaccharomyces pombe provides an attractive system for the study of unicellular differentiation, especially the processes of meiosis and genetic recombination. Yeasts are easily cultured, sporulated, and germinated and are quite amenable to genetic analysis. Sporulation occurs when cells preadapted to oxidative growth are incubated in a medium such as 1% potassium acetate in the absence of a nitrogen source. Sporulation occurs in diploids or cells of higher ploidy that carry both a- and α-mating type alleles, diploids of genotype a/a or α/α do not sporulate. Sporulation is distinctly different from the vegetative cell cycle, as the conditions that support vegetative growth do not support sporulation of strains of S. cerevisiae. Sporulation occurs under pseudostarvation conditions in which the cells do not proliferate. During sporulation, cells undergo meiosis rather than mitosis and yield four haploid genetic complements enclosed in four refractile spores within an ascus. The chapter identifies areas toward which major attention has been directed in study of sporulation and germination. Identification of stages during sporulation is described and isolation of mutants specific for sporulation is explained. Methods for measuring germination and outgrowth are also described in the chapter.