Genetic Mapping in Saccharomyces cerevisiae

Abstract

The first genetic map of Saccharomyces cerevisiae was published by Lindegren (1949), and several revisions of the map have appeared since then (Hawthorne and Mortimer 1960Hawthorne and Mortimer 1968; Lindegren et al. 1962; Mortimer and Hawthorne 1966, 1973, 1975). The latest version of the map is included in Appendix II. In this paper the various techniques used to locate genes on the genetic map of the yeast S. cerevisiae will be reviewed. Some of these techniques have been described in detail elsewhere (Mortimer and Hawthorne 1969Mortimer and Hawthorne 1975; Wickner 1979) and will be discussed only partially here.

Both meiotic and mitotic approaches have been developed to map yeast genes. The meiotic approaches include tetrad analysis, random spore analysis, and trisomic analysis. The mitotic cell-cycle events that yield mapping information are mitotic crossing-over and mitotic chromosome loss.

MEIOTIC MAPPING TECHNIQUES
Tetrad Analysis
The life cycle of S. cerevisiae normally alternates between diplophase and haplophase. Both ploidies can exist as stable cultures. In heterothallic strains the haploid cultures are of two mating types, a and α. Mating of a and α cells results in a/α diploids that are unable to mate but can undergo meiosis. The four haploid products resulting from meiosis of a diploid cell are contained within the wall of the mother cell (the ascus). Digestion of the ascus wall and separation of the spores by micromanipulation yield four clones that represent the four haploid meiotic products (reviewed in Mortimer and Hawthorne 1969). Analysis of the segregation patterns of different heterozygous markers among...