title: Meiotic Consequences of Genetic Divergence Across the Murine Pseudoautosomal Region.
abstract: The production of haploid gametes during meiosis is dependent on the homology-driven processes of pairing, synapsis, and recombination. On the mammalian heterogametic sex chromosomes, these key meiotic activities are confined to the pseudoautosomal region (PAR), a short region of near-perfect sequence homology between theXandYchromosomes. Despite its established importance for meiosis, the PAR is rapidly evolving, raising the question of how properX/Ysegregation is buffered against the accumulation of homology-disrupting mutations. Here, I investigate the interplay of PAR evolution and function in two interfertile house mouse subspecies characterized by structurally divergent PARs,Mus musculus domesticusandM. m. castaneusUsing cytogenetic methods to visualize the sex chromosomes at meiosis, I show that intersubspecific F1hybrids harbor an increased frequency of pachytene spermatocytes with unsynapsed sex chromosomes. This high rate of asynapsis is due, in part, to the premature release of synaptic associations prior to completion of prophase I. Further, I show that when sex chromosomes do synapse in intersubspecific hybrids, recombination is reduced across the paired region. Together, these meiotic defects afflict ∼50% of spermatocytes from F1hybrids and lead to increased apoptosis in meiotically dividing cells. Despite flagrant disruption of the meiotic program, a subset of spermatocytes complete meiosis and intersubspecific F1males remain fertile. These findings cast light on the meiotic constraints that shape sex chromosome evolution and offer initial clues to resolve the paradox raised by the rapid evolution of this functionally significant locus.
authors.affiliation: Department of Biological Sciences, Initiative in Biological Complexity, North Carolina State University, Raleigh, North Carolina 27695 beth.dumont@jax.org.
authors.forename: Beth L
authors.identifier: 0000-0003-0918-0389
authors.initials: BL
authors.lastname: Dumont
mesh_terms: D000818:Animals; D019143:Evolution, Molecular; D005260:Female; D008297:Male; D008540:Meiosis / Q000235:genetics*; D051379:Mice; D000071439:Pseudoautosomal Regions / Q000235:genetics*
keywords: Mus musculus; aneuploidy; meiosis; pseudoautosomal region; recombination