Fig. 19a. Synthetic genetic array methodology. (i) A MATalpha strain carrying a query mutation (bni1-delta) linked to a dominant selectable marker, such as the nourseothricin-resistance marker, natMX, that confers resistance to the antibiotic nourseothricin, and an MFA1pr-HIS3 reporter, is crossed to an ordered array of MATa viable yeast deletion mutants, each carrying a gene deletion mutation (xxx-delta) linked to a kanamycin-resistance marker (kanMX). Growth of the resultant heterozygous diploids is selected for on medium containing nourseothricin and kanamycin. (ii) The heterozygous diploids are transferred to medium with reduced levels of carbon and nitrogen to induce sporulation and the formation of haploid meiotic spore progeny. (iii) Spores are transferred to synthetic medium lacking histidine, which allows for selective germination of MATa meiotic progeny, because these cells express the MFA1pr-HIS3 reporter specifically. (iv) The MATa meiotic progeny are transferred to medium that contains both nourseothricin and kanamycin, which then selects for growth of double-mutant meiotic progeny.
Fig. 19b. Genetic interaction network representing the synthetic lethal/sick interactions determined by SGA analysis. Genes are represented as nodes, and interactions are represented as edges that connect the nodes; 291 interactions and 204 genes are shown. All of the interactions were confirmed by tetrad analysis, with 8 to 14 tetrads examined in each case. The genes are colored according to their cellular roles as described in the Yeast Protein Database, which, unfortunately, subsequently became available only through a paid subscription.