FIG. 4.

Cells with an active Sxi1α/Sxi2a heterodimer are self-filamentous. (A) The left panel shows the self-filamentous phenotype of the α SXI2a strain on V8 medium (pH 5) after 3 weeks of incubation. The right panel shows mating filaments produced in a wild-type a × α cross after 3 weeks. (B) DAPI (4′,6′-diamidino-2-phenylindole) staining shows that the filaments produced by the α SXI2a strain are monokaryons (left), in contrast to the dikaryons (right) observed in a wild-type a × α cross. Arrowheads indicate two nuclei present in clamp cells in α SXI2a hyphae. DIC, differential interference contrast.