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Distinct properties of the XY pseudoautosomal region crucial for male meiosis.

ABSTRACT: Meiosis requires that each chromosome find its homologous partner and undergo at least one crossover. X-Y chromosome segregation hinges on efficient crossing-over in a very small region of homology, the pseudoautosomal region (PAR). We find that mouse PAR DNA occupies unusually long chromosome axes, potentially as shorter chromatin loops, predicted to promote double-strand break (DSB) formation. Most PARs show delayed appearance of RAD51/DMC1 foci, which mark DSB ends, and all PARs undergo delayed DSB-mediated homologous pairing. Analysis of Spo11? isoform-specific transgenic mice revealed that late RAD51/DMC1 foci in the PAR are genetically distinct from both early PAR foci and global foci and that late PAR foci promote efficient X-Y pairing, recombination, and male fertility. Our findings uncover specific mechanisms that surmount the unique challenges of X-Y recombination.

SUBMITTER: Kauppi L

PROVIDER: S-EPMC3151169 | biostudies-literature | 2011 Feb

REPOSITORIES: biostudies-literature

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Distinct properties of the XY pseudoautosomal region crucial for male meiosis.

Kauppi Liisa L Barchi Marco M Baudat Frédéric F Romanienko Peter J PJ Keeney Scott S Jasin Maria M

Science (New York, N.Y.) 20110201 6019

Meiosis requires that each chromosome find its homologous partner and undergo at least one crossover. X-Y chromosome segregation hinges on efficient crossing-over in a very small region of homology, the pseudoautosomal region (PAR). We find that mouse PAR DNA occupies unusually long chromosome axes, potentially as shorter chromatin loops, predicted to promote double-strand break (DSB) formation. Most PARs show delayed appearance of RAD51/DMC1 foci, which mark DSB ends, and all PARs undergo delay ...[more]

PMID: 21330546

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Project description:Background Sex chromosomes are subject to evolutionary pressures distinct from the remainder of the genome, shaping their structure and sequence content. We are interested in the sex chromosomes of domestic pigs (Sus scrofa), how their structure and gene content compares and contrasts with other mammalian species, and the role of gonosomal genes in fertility. This requires an understanding of the XY-homologous sequence on these chromosomes. To this end, we performed microarray-based comparative genomic hybridisation (array-CGH) with male and female Duroc genomic DNA on a pig X-chromosome BAC tiling-path microarray. Putative XY-homologous BACs from regions of interest were subsequently FISH mapped. Results We show that the porcine PAR is approximately 6.5-6.9Mb at the beginning of the short arm of the X, with gene content reflective of the artiodactyl common ancestor. Our array-CGH data also shows an XY-homologous region close to the end of the X long arm, spanning three X BACs. These BACs were FISH mapped, and paint the entire long arm of SSCY. Further clones of interest revealed X-autosomal homology or regions containing repetitive content. Conclusions This study has identified regions of XY homology in the pig genome, and defined the boundary of the PAR on the X chromosome. This adds to our understanding of the evolution of the sex chromosomes in different mammalian lineages, and will prove valuable for future comparative genomic work in suids and for the construction and annotation of the genome sequence for the sex chromosomes. Our finding that the SSCYq repetitive content has corresponding sequence on the X chromosome gives further insight into structure of SSCY, and suggests further functionally important sequences remain to be discovered on the X and Y. Genomic DNA from male and female Duroc pigs were competitively hybridised to an X-chromosome BAC tiling-path microarray. Male DNA came from the animal used for Y chromosome sequencing at the Wellcome Trust Sanger Institute. Female DNA came from a fibroblast cell line. 4 hybridisations were performed. Clones with successful hybridisation in 2 or more of these replicates were used for analysis and detection of potential regions of XY homology.

Dataset Information

Distinct properties of the XY pseudoautosomal region crucial for male meiosis.

Publications

Distinct properties of the XY pseudoautosomal region crucial for male meiosis.

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