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Vertebrate reproductive science and technology

Analysis of SINE and LINE repeat content of Y chromosomes in the platypus, Ornithorhynchus anatinus

R. Daniel Kortschak A , Enkhjargal Tsend-Ayush A and Frank Grützner A B
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- Author Affiliations

A Discipline of Genetics, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, SA 5005, Australia.

B Corresponding author. Email:

Reproduction, Fertility and Development 21(8) 964-975
Submitted: 5 April 2009  Accepted: 21 June 2009   Published: 30 October 2009


Monotremes feature an extraordinary sex-chromosome system that consists of five X and five Y chromosomes in males. These sex chromosomes share homology with bird sex chromosomes but no homology with the therian X. The genome of a female platypus was recently completed, providing unique insights into sequence and gene content of autosomes and X chromosomes, but no Y-specific sequence has so far been analysed. Here we report the isolation, sequencing and analysis of ~700 kb of sequence of the non-recombining regions of Y2, Y3 and Y5, which revealed differences in base composition and repeat content between autosomes and sex chromosomes, and within the sex chromosomes themselves. This provides the first insights into repeat content of Y chromosomes in platypus, which overall show similar patterns of repeat composition to Y chromosomes in other species. Interestingly, we also observed differences between the various Y chromosomes, and in combination with timing and activity patterns we provide an approach that can be used to examine the evolutionary history of the platypus sex-chromosome chain.

Additional keywords: genome evolution, repetitive element, Y-chromosome evolution.


We would like to acknowledge Willem Rens and Malcolm Ferguson-Smith (Cambridge Resource Centre for Comparative Genomics at the University of Cambridge) for providing their microdissected Y5-chromosome paints, and Jürgen Schmitz (University of Münster) and David Adelson (University of Adelaide) and the two anonymous reviewers for their constructive suggestions. This work is funded by the Australian Research Council (DP0664267); F.G. is an ARC Australian Research Fellow and E.T.A. is an ARC Postdoctoral Fellow. The authors declare that there is no conflict of interest that would prejudice the impartiality of this scientific work.


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