Figure 4 .

Effect of Δswi2L on mating-type switching. (A) Structure of the swi2L::ura4 allele is diagrammed. A 1.8-kb ura4 HindIII fragment was inserted in the translation initiation site (ATG) of the swi2L gene. (B) Northern blot analysis of wild-type (SP976) and the swi2L::ura4 (CY345) cultures. RNAs prepared from cultures grown in PMA medium were analyzed with the Swi2P probe (Figure 3A). (C) Iodine-staining colony phenotype. Numbers below each colony reflect their efficiency of sporulation. (D) The mat1 M/P ratio of cultures was determined with the method described in Figure 2B.