Tetrad, random spore, and molecular analysis of meiotic segregation and recombination.

The power of Saccharomyces cerevisiae as an experimental organism derives from its genetic tractability. Mutant variants can be isolated or constructed and phenotypically characterized with relative ease. In addition, the ability to recover and characterize all four products of meiosis, as haploid spores in a tetrad ascus, greatly facilitates determining the allelic composition of variants, measuring linkage relationships between alleles, and constructing new allele combinations for the analysis of genetic interactions. Saccharomyces cerevisiae also is a preeminent model organism for the study of meiotic recombination, by analysis of tetrads, by analysis of populations of single spores (often called random spore analysis), and by direct monitoring of recombination at the DNA level. This chapter contains methods for tetrad dissection, for random spore preparation, and for preparing DNA for molecular analysis from liquid cultures undergoing synchronous meiosis.