High frequency fo X-Y chromosome dissociation in primary spermatocytes of F1 hybrids between Japanese wild mice (Mus musculus molossinus) and inbred laboratory mice

Cytogenet Cell Genet. 1981;29(3):166-75. doi: 10.1159/000131565.

Abstract

In the hybrids between Japanese wild mice (Mus musculus molossinus) and inbred laboratory mice (BALB/c and B10.BR, which were probably derived from M. m. domesticus), the X and Y chromosomes dissociated precociously at the first meiotic metaphase in some 70% of spermatocytes; that percentage was only 8.9% in inbred laboratory mice and 21.1% in wild mice. X-Y dissociation began at least at early diakinesis and continued during metaphase I (MI). Some autosomes of the hybrid (10.1%) and BALB/c (10.6%) mice also dissociated precociously, but there was no distinctive correlation between X-Y and autosomal dissociation. In B10 or B6 congenic lines with a Y chromosome from wild M. m. molossinus, there was an apparent tendency for the percentage of precocious X-Y dissociation to decrease with an increasing number of back cross generations. Based on these observations we concluded that: 1. the X-Y dissociation found is genetically controlled, perhaps by multiple genes; 2. these genes are located on autosomes and are active only when they are heterozygous; 3. the frequent dissociation of the sex chromosomes neither affects male fertility nor induces non-disjunction of the X and Y chromosomes, though it significantly reduces testes weight.

MeSH terms

  • Animals
  • Chromosomes / physiology
  • Crosses, Genetic
  • Female
  • Hybridization, Genetic
  • Male
  • Meiosis*
  • Mice / genetics*
  • Mice, Inbred BALB C
  • Mice, Inbred Strains / genetics*
  • Sex Chromosomes / physiology*
  • Spermatocytes / physiology