The rad59 mutant alleles have distinct effects on survival in cells that are defective for lagging strand synthesis. Diploid strains heterozygous at the RAD27 (rad27::LEU2/RAD27) and RAD59 (rad59/RAD59) loci were sporulated and tetrads dissected onto YPD medium. The resulting colonies were examined after 72 h of growth at 30°. Colonies from five representative tetrads from each strain are displayed. The genotype of each colony was determined by PCR as described in the Methods. In the inverted image, colonies possessing a rad27::LEU2 allele are boxed in black, and those possessing a rad59 allele are circled in white.