Chromosome Research

, Volume 18, Issue 5, pp 543–553

A W-linked palindrome and gene conversion in New World sparrows and blackbirds

  • Jamie K. Davis
  • Pamela J. Thomas
  • NISC Comparative Sequencing Program
  • James W. Thomas

DOI: 10.1007/s10577-010-9134-y

Cite this article as:
Davis, J.K., Thomas, P.J., NISC Comparative Sequencing Program et al. Chromosome Res (2010) 18: 543. doi:10.1007/s10577-010-9134-y


A hallmark feature of the male-specific region of the human Y chromosome is the presence of large and near-identical palindromes. These palindromes are maintained in a state of near identity via gene conversion between the arms of the palindrome, and both neutral and selection-based theories have been proposed to explain their enrichment on the human Y and X chromosomes. While those proposed theories would be applicable to sex chromosomes in other species, it has not been established whether near-identical palindromes are a common feature of sex chromosomes in a broader range of taxa, including other tetrapods. Here, we report the genomic sequencing and features of a 279-kb region of the non-recombining portion of the W chromosome spanning the CHD1W locus in a New World sparrow, the white-throated sparrow (Zonotrichia albicollis), and the corresponding region on the Z chromosome. As has been observed for other Y and W chromosomes, we detected a high repetitive element content (51%) and low gene content on the white-throated sparrow W chromosome. In addition, we identified a 22-kb near-identical (>99%) palindrome on the W chromosome that flanks the 5′ end of the CHD1W gene. Signatures of gene conversion were readily detected between the arms of this palindrome, as was the presence of this palindrome in other New World sparrows and blackbirds. Near-identical palindromes are therefore present on the avian W chromosome and may persist due to the same forces proposed for the enrichment of these elements on the human sex chromosomes.


palindrome gene conversion sex chromosome 



Bacterial artificial chromosome


Chromo-helicase DNA-binding protein, W chromosome


Chromo-helicase DNA-binding protein, Z chromosome


Children’s Hospital Oakland Research Institute


deoxy-nucleotide triphosphate


Histidine triad nucleotide binding protein W


Kilobase pairs


Meiotic sex chromosome inactivation


Male-specific region of the Y chromosome


Polymerase chain reaction


RAS p21 protein activator (GTPase activating protein) 1


RGM domain family, member B


University of Washington Burke Museum

Copyright information

© Springer Science+Business Media B.V. 2010

Authors and Affiliations

  • Jamie K. Davis
    • 1
  • Pamela J. Thomas
    • 2
  • NISC Comparative Sequencing Program
    • 2
  • James W. Thomas
    • 1
  1. 1.Department of Human GeneticsEmory University School of MedicineAtlantaUSA
  2. 2.Genome Technology Branch and NIH Intramural Sequencing Center, National Human Genome Research InstituteNational Institutes of HealthBethesdaUSA

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