Jeremiah D Degenhardt: Mapping of The Pseudoautosomal Boundary in Four Canid Species and Rhesus Maca

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Jeremiah D Degenhardt, Biological Statistics & Computational Biology, Cornell University
Tuesday, February 16, 2010, 12:15 PM to 1:15 PM
Location: 599 Engineering 2 Building
Hosted By David Haussler, Center for Biomolecular Science & Engineering

Abstract

The mammalian pseudoautosomal region (PAR) is a short segment of  homology on the X and Y-chromosomes. This shared region allows for  pairing, and therefore proper segregation, of the sex chomosomes during  male meiosis, and represents the sole region of X/Y recombination. To  date this region has been mapped in only a small number of taxonomically divergent mammalian groups (including human/chimp, mouse, horse cow and  domestic dogs). Comparative analysis of these groups has shown that  there has been an independent reduction in the size of the PAR compared  to the ancestral eutherian PAR in each of these groups. Here we present  a novel method for the mapping of the PAR boundary using a comparison of  male and female intensity data and heterozygosity from microarray data and map the location of this boundary in the domestic dog and wolf, coyote and jackal and rhesus macaque. We show that the position of the PAR boundary is consistent between canid species and also between the canines and the domestic cat suggesting that the position of the PAR boundary has been relatively stable over the last ~42 million years of carnivore evolution. As well, the rhesus macaque PAR position is shown to be consistent with that of humans and chimpanzee. However, we also find evidence of lower recombination near the PAR boundary in the domestic dog consistent with extensive PAR attrition in this group, suggesting that the exact location of the boundary may show some instability. We examine the gene content of newly mapped PARs and compare this to the previous studies. We find a high degree of similarity in the genic content of the canine PAR and human PAR and adjacent X and Y chromosomal regions but little similarity with the mouse PAR. We also find evidence to suggest the existence of assembly errors in the macaque reference genome. Based on these findings we suggest a most extensive restructuring of the sex chromosomes in any sequenced organism has occurred in the mouse.