Figure 3.—

Illegitimate matings in strains with mre11 mutations: plate tests of legitimate and illegitimate mating. The MATα wild-type parent strain (MS71) and isogenic GAL-POL1, GAL-POL1 mre11Δ, and GAL-POL1 mre11-H125N (a mutation eliminating the endonuclease activity of Mre11p; Moreau et al. 1999) strains were streaked on medium containing low levels of galactose (0.005%) (resulting in low levels of DNA polymerase α) and grown overnight. These strains were then mated by replica plating to four tester strains: 1225 MATa, 1225 MATα, mre11Δ MATα, and mre11-H125N MATα. After the strains were allowed to mate overnight, they were replica plated to medium on which only diploids were capable of growth.