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Type: Journal article
Title: In the platypus a meiotic chain of ten sex chromosomes shares genes with the bird Z and mammal X chromosomes
Author: Grutzner, F.
Rens, W.
Tsend-Ayush, E.
El-Mogharbel, N.
O'Brien, P.
Jones, R.
Ferguson-Smith, M.
Graves, J.
Citation: Nature, 2004; 432(7019):913-917
Publisher: Nature Publishing Group
Issue Date: 2004
ISSN: 0028-0836
Statement of
Frank Grützner, Willem Rens, Enkhjargal Tsend-Ayush, Nisrine El-Mogharbel, Patricia C. M. O'Brien, Russell C. Jones, Malcolm A. Ferguson-Smith and Jennifer A. Marshall Graves
Abstract: Two centuries after the duck-billed platypus was discovered, monotreme chromosome systems remain deeply puzzling. Karyotypes of males1, or of both sexes2–4, were claimed to contain several unpaired chromosomes (including the X chromosome) that form a multi-chromosomal chain at meiosis. Such meiotic chains exist in plants5 and insects6 but are rare in vertebrates7. How the platypus chromosome system works to determine sex and produce balanced gametes has been controversial for decades1– 4. Here we demonstrate that platypus have five malespecific 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.
Keywords: Spermatozoa
Sex Chromosomes
X Chromosome
Y Chromosome
Chromosome Painting
Evolution, Molecular
Molecular Sequence Data
Sex Determination Processes
DOI: 10.1038/nature03021
Appears in Collections:Aurora harvest 6
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