International Mammalian Genome Society

logo18th International Mouse Genome Conference

17-22 October 2004, Seattle, USA


PLENARY PRESENTATION

TUESDAY OCTOBER 19

2.00pm – 2.30pm

SEQUENCE OF THE MOUSE Y CHROMOSOME

Alfoldi JE1, Skaletsky H1, Graves T2, Minx P2, Wilson RK2, Rozen S1, Page DC1

1 Howard Hughes Medical Institute, Whitehead Institute, and Department of Biology, Massachusetts Institute of Technology, Cambridge, United States, 2 Genome Sequencing Center, Washington University School of Medicine, St. Louis, United States

Y chromosomes have no partner with which to cross-over during meiosis, and so were once thought to be doomed to degeneration and gene loss. However, the recent discovery of palindromes on the human Y chromosome has given us hope of the continued survival of Y genes, since palindromes could be protecting their genes by gene conversion.

The sequencing of the mouse Y chromosome was begun with the hope that it too has palindromes, and that these palindromes could be studied more easily in a more tractable organism. Now that some mouse Y sequence has been produced, we can see that this chromosome contains not only palindromes, but a remarkable feature never seen before in any genome – the Huge Repeat array.

95% of the sequence of the mouse Y consists of a single large repeat – approximately 200 copies of a 500 kb repeat unit, all found on the Y’s long arm. The repeat units are 90-99.9% identical, euchromatic, internally repetitive and contain two gene families, Ssty (Y-linked spermiogenesis specific transcript) and Sly (Sycp3-like, Y-linked). This Huge Repeat array is unlike anything found on the palindrome-containing human Y chromosome or the heterochromatin-filled Drosophila Y chromosome. It is also extremely unusual within the mouse genome as this genome has very low segmental duplication, especially when compared to the human genome. The short arm of the mouse Y chromosome does not contain Huge Repeat sequence. However, it does contain palindromes, similar to the human Y, as well as several spermatogenesis-related genes.

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