9
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: not found

      In the platypus a meiotic chain of ten sex chromosomes shares genes with the bird Z and mammal X chromosomes.

      Nature
      Animals, Birds, genetics, Chromosome Painting, Evolution, Molecular, Female, Male, Mammals, Meiosis, Metaphase, Molecular Sequence Data, Platypus, Sex Chromosomes, Sex Determination Processes, Spermatozoa, cytology, metabolism, Telomere, X Chromosome, Y Chromosome

      Read this article at

      ScienceOpenPublisherPubMed
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          Two centuries after the duck-billed platypus was discovered, monotreme chromosome systems remain deeply puzzling. Karyotypes of males, or of both sexes, were claimed to contain several unpaired chromosomes (including the X chromosome) that form a multi-chromosomal chain at meiosis. Such meiotic chains exist in plants and insects but are rare in vertebrates. How the platypus chromosome system works to determine sex and produce balanced gametes has been controversial for decades. Here we demonstrate that platypus have five male-specific chromosomes (Y chromosomes) and five chromosomes present in one copy in males and two copies in females (X chromosomes). These ten chromosomes form a multivalent chain at male meiosis, adopting an alternating pattern to segregate into XXXXX-bearing and YYYYY-bearing sperm. Which, if any, of these sex chromosomes bears one or more sex-determining genes remains unknown. The largest X chromosome, with homology to the human X chromosome, lies at one end of the chain, and a chromosome with homology to the bird Z chromosome lies near the other end. This suggests an evolutionary link between mammal and bird sex chromosome systems, which were previously thought to have evolved independently.

          Related collections

          Author and article information

          Comments

          Comment on this article