Male sterility caused byp6H andqk mutations is not corrected in chimeric mice

Abstract

It is not known if the male sterility caused by the pleiotropic mutations p^6H (pink‐eyed 6H) and qk (quaking) is intrinsic or extrinsic to spermatogenic cells. This question was addressed by juxtaposing mutant and normal cells in the testes of chimeric mice and determining whether the mutant germ cells could form functional sperm. Twenty‐one male chimeras consisting of normal cells and p^6H/p^6H or qk/qk cells were analyzed. For each, breeding productivity and testicular and sperm morphology were determined. Karyotypes and isozyme analyses were performed to identify the two cellular components of each chimera. All male chimeras that contained p^6H/p^6H, XY cells were sterile. Although some chimeras with a qk/qk, XY mutant component were fertile, none produced offspring from the homozygous qk component. Spermatids of the sterile chimeras showed abnormalities characteristic of the mutations. We conclude from this study that the presence of normal XY germ and somatic cells in the testis did not rescue the male sterile phenotype of homozygous p^6H or qk XY germ cells. Therefore, the action of these mutant genes in causing sperm abnormalities and sterility is autonomous to the germ cells.