Comparison of the Z and W sex chromosomal architectures in elegant crested tinamou (Eudromia elegans) and ostrich (Struthio camelus) and the process of sex chromosome differentiation in palaeognathous birds

Chromosoma. 2007 Apr;116(2):159-73. doi: 10.1007/s00412-006-0088-y. Epub 2007 Jan 12.


To clarify the process of avian sex chromosome differentiation in palaeognathous birds, we performed molecular and cytogenetic characterization of W chromosome-specific repetitive DNA sequences for elegant crested tinamou (Eudromia elegans, Tinamiformes) and constructed comparative cytogenetic maps of the Z and W chromosomes with nine chicken Z-linked gene homologues for E. elegans and ostrich (Struthio camelus, Struthioniformes). A novel family of W-specific repetitive sequences isolated from E. elegans was found to be composed of guanine- and cytosine-rich 293-bp elements that were tandemly arrayed in the genome as satellite DNA. No nucleotide sequence homologies were found for the Struthioniformes and neognathous birds. The comparative cytogenetic maps of the Z and W chromosomes of E. elegans and S. camelus revealed that there are partial deletions in the proximal regions of the W chromosomes in the two species, and the W chromosome is more differentiated in E. elegans than in S. camelus. These results suggest that a deletion firstly occurred in the proximal region close to the centromere of the acrocentric proto-W chromosome and advanced toward the distal region. In E. elegans, the W-specific repeated sequence elements were amplified site-specifically after deletion of a large part of the W chromosome occurred.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Sequence
  • Blotting, Southern
  • Chromosome Banding
  • Chromosome Mapping
  • DNA Primers
  • Evolution, Molecular*
  • Female
  • Genetic Variation*
  • In Situ Hybridization, Fluorescence
  • Male
  • Molecular Sequence Data
  • Palaeognathae / genetics*
  • Sequence Analysis, DNA
  • Sequence Deletion / genetics
  • Sex Chromosomes / genetics*
  • Species Specificity
  • Tandem Repeat Sequences / genetics


  • DNA Primers