Complementation and noncomplementation in heterokaryons of three unlinked pigment mutants of the fowl.

This study shows that melanocyte heterokaryons formed between cells of the blue and recessive white genotypes complement one another to produce normal pigmentation, while heterokaryons of the blue and pinkeye genotypes fail to complement. The simplest interpretation of these findings is that the blue and recessive white mutations affect different aspects of pigment synthesis so that when both kinds of nuclei exist in the same cytoplasm, they can correct (complement) each other's defect. On the other hand, the blue and pinkeye mutations, although unlinked, apparently affect the same aspect of pigment synthesis so that when both kinds of nuclei are in a common cytoplasm, they cannot correct each other's defect. This suggests that one of these two loci exerts some kind of control, or "regulation," over the other. It has previously been shown that recessive white--pinkeye heterokaryons can complement. Thus, only two heterokaryon complementation groups are evident within the three mutants examined.