Figure 3.

Creation and testing of knockout heterokaryons homozygous for disrupted ATU genes in the mic (ΔATU) and containing only wild-type ATU genes in the mac. Chx is a dominant gene conferring resistance to cycloheximide (cy-r), whereas the wild-type Chx⁺ is sensitive (cy-s). Mpr is a dominant gene conferring resistance to 6-methylpurine (mp-r), to which cells with the wild-type Mpr⁺ gene are sensitive (mp-s). Roman numerals indicate mating types; mating types not determined are indicated by ?. Note that in cross d only a mutant ΔATU/ΔATU round I product of cross c is shown. An approximately equal number of nonmutant ATU/ATU round I cells are obtained that do not yield any pm-r progeny. The genotype of the Mpr locus in round I exconjugants was not determined. Values obtained for test crosses b and d are from a single subline.