Gene-centromere mapping of bovine DYA, DRB3, and PRL using secondary oocytes and first polar bodies: evidence for four-strand double crossovers between DYA and DRB3

Genomics. 1995 May 1;27(1):33-9. doi: 10.1006/geno.1995.1005.


A genetic map consisting of three loci anchored at the centromere of bovine chromosome 23 was constructed by genotyping secondary oocytes (SO) and first polar bodies (PB1) using a polymerase chain reaction (PCR)-based approach. Primary oocytes arrested in prophase of meiosis I were stimulated in vitro to resume division and extrude PB1. Sixty SO and their matched PB1 were collected from 14 cows by micro-manipulation, subjected to amplification of the whole genome by primer extension preamplification, and genotyped independently for the linked genes PRL, DRB3, and DYA by PCR-RFLP analysis. Single-locus analysis of gene-centromere recombination rates were theta cen-DYA = 0.042, theta cen-DRB3 = 0.113, and theta cen-PRL = 0.166. The most likely order is cen-DYA-DRB3-PRL. Analysis of typing data from 3 cows revealed three meiotic divisions consistent with "linkage phase exchange" between DYA and DRB3 or PRL. One of the three linkage phase exchanges was confirmed by complementary genotypes in a matched secondary oocyte-first polar body pair. Such linkage phase exchanges could result from four-strand double crossovers between homologous chromosomes. Because all four gametes produced by four-strand double crossovers will be recombinant, more frequent occurrence of such events in females may explain the sexual dimorphism in genetic maps. Alternatively, four-strand crossovers could represent a type of recombination hotspot between DYA and DRB3, suggesting a mechanism for the high recombination frequency (15%) between these two class II genes of the bovine major histocompatibility complex.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Cattle / genetics*
  • Chromosome Mapping
  • Crossing Over, Genetic*
  • Female
  • Genes, MHC Class II*
  • Genetic Linkage
  • HLA-DR Antigens / genetics*
  • HLA-DRB3 Chains
  • Histocompatibility Antigens Class II / genetics*
  • Meiosis
  • Oocytes / metabolism
  • Polymerase Chain Reaction
  • Prolactin / genetics*


  • BoLA-DYA protein, Bos indicus
  • HLA-DR Antigens
  • HLA-DRB3 Chains
  • Histocompatibility Antigens Class II
  • Prolactin