title: 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.
abstract: 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.
authors.affiliation: Laboratory of Cytogenetics, Division of Bioscience, Graduate School of Environmental Earth Science, Hokkaido University, North 10 West 8, Sapporo 060-0810, Japan.
authors.forename: Yayoi
authors.initials: Y
authors.lastname: Tsuda
authors.forename: Chizuko
authors.initials: C
authors.lastname: Nishida-Umehara
authors.forename: Junko
authors.initials: J
authors.lastname: Ishijima
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Yamada
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Matsuda
mesh_terms: D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D002871:Chromosome Banding; D002874:Chromosome Mapping; D017931:DNA Primers; D019143:Evolution, Molecular; D005260:Female; D014644:Genetic Variation; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D008969:Molecular Sequence Data; D046108:Palaeognathae / Q000235:genetics*; D017422:Sequence Analysis, DNA; D017384:Sequence Deletion / Q000235:genetics; D012730:Sex Chromosomes / Q000235:genetics*; D013045:Species Specificity; D020080:Tandem Repeat Sequences / Q000235:genetics
chemical_list: D017931:DNA Primers