Platypus chain reaction: Directional and ordered meiotic pairing of the multiple sex chromosome chain in Ornithorhynchus anatinus

Tasman Daish, Aaron Casey, Frank Grützner

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


Monotremes are phylogenetically and phenotypically unique animals with an unusually complex sex chromosome system that is composed often chromosomes in platypus and nine in echidna. These chromosomes are alternately linked (X1Y1, X2Y2,...) at meiosis via pseudoautosomal regions and segregate to form spermatozoa containing either X or Y chromosomes. The physical and epigenetic mechanisms involved in pairing and assembly of the complex sex chromosome chain in early meiotic prophase I are completely unknown. We have analysed the pairing dynamics of specific sex chromosome pseudoautosomal regions in platypus spermatocytes during prophase of meiosis I. Our data show a highly coordinated pairing process that begins at the terminal Y5 chromosome and completes with the union of sex chromosomes X1Y1. The consistency of this ordered assembly of the chain is remarkable and raises questions about the mechanisms and factors that regulate the differential pairing of sex chromosomes and how this relates to potential meiotic silencing mechanisms and alternate segregation.

Original languageEnglish
Pages (from-to)976-984
Number of pages9
JournalReproduction, Fertility and Development
Issue number8
Publication statusPublished - 1 Dec 2009


  • Chromosome pairing
  • Meiosis
  • Pseudoautosomal regions
  • Telomeres

ASJC Scopus subject areas

  • Biotechnology
  • Reproductive Medicine
  • Animal Science and Zoology
  • Molecular Biology
  • Genetics
  • Endocrinology
  • Developmental Biology

Cite this