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. 2014 Oct 27;111(45):E4851–E4858. doi: 10.1073/pnas.1416014111

Fig. 4.

Fig. 4.

Mating-type switching by inversion in H. polymorpha. (A) Crossing two strains in the same orientation results in diploids that are heterozygous for orientation. Haploid MATalpha (SHY2-3 and SHY2-24) and MATa (SHY2-4 and SHY2-28) strains with complementary auxotrophic mutations were obtained by random spore analysis of a sporulated diploid (SHY2) and were mated to produce diploids (SHY7 from alpha × alpha and SHY10 from a × a). (Left) Schematics indicate the MAT locus organization in the strains used in each cross and the resulting diploids. Purple ovals represent the centromere. The MAT genes closer to the centromere are silenced (pale colors). (Right) Gel images show amplification across the IR regions with the primer combinations indicated. (B) MAT locus inversion is induced by nitrogen limitation. Gel images show MAT locus organization for haploid MATalpha (SHY2-3) and MATa (SHY2-4) strains after growth for 12 h in YPD, minimal medium without nitrogen (NaKG), and NaKG supplemented with 40 mM ammonium sulfate as a nitrogen source.