COMPLEMENTATION ANALYSES FOR 45 MUTATIONS ENCOMPASSING THE PINK-EYED DILUTION (P) LOCUS OF THE MOUSE

The homozygous and heterozygous phenotypes are described and character ized for 45 new pink-eyed dilution (p) locus mutations, most of them r adiation-induced, that affect survival at various stages of mouse deve lopment. Cytogenetically detectable aberrations were found in three of the new p mutations (large deletion, inversion, translocation), with band 7C involved in each case. The complementation map developed from the study of 810 types of compound heterozygotes identifies five funct ional units: jls and jlm (two distinct juvenile-fitness functions, the latter associated with neuromuscular defects), pl-1 and pl-2 (associa ted with early-postimplantation and preimplantation death, respectivel y), and nl [neonatal lethality associated with cleft palate (the frequ ency of rare ''escapers'' from this defect varied with the genotype)]. Orientation of these units relative to genetic markers is as follows: centromere, Gas-2 pl-1,jls, jlm p, nl (equatable to cp1 = Gabrb3); pl -2 probably resides in the c-deletion complex. pl-1 does not mask prei mplantation lethals between Gas2 and p; and no genes affecting surviva l are located between p and cp1. The alleles specifying mottling or da rker pigment (generically, p(m) and p(x), respectively) probably do no t represent deletions of p-coding sequences but could be small rearran gements involving proximal regulatory elements.