The horse pseudoautosomal region (PAR): characterization and comparison with the human, chimp and mouse PARs.
Abstract: The pseudoautosomal region (PAR) is a genomic segment on mammalian sex chromosomes where sequence homology mimics that seen between autosomal homologues. The region is essential for pairing and proper segregation of sex chromosomes during male meiosis. As yet, only human/chimp and mouse PARs have been characterized. The two groups of species differ dramatically in gene content and size of the PAR and therefore do not provide clues about the likely evolution and constitution of PAR among mammals. Here we characterize the equine PAR by i) isolating and arranging 71 BACs containing 129 markers (110 STS and 19 genes) into two contigs spanning the region, ii) precisely localizing the pseudoautosomal boundary (PAB), and iii) describing part of the contiguous X- and Y-specific regions. We also report the discovery of an approximately 200 kb region in the middle of the PAR that is present in the male-specific region of the Y (MSY) as well. Such duplication is a novel observation in mammals. Further, comparison of the equine PAR with the human counterpart shows that despite containing orthologs from an additional 1 Mb region beyond the human PAR1, the equine PAR is around 0.9 Mb smaller than the size of the human PAR. We theorize that the PAR varies in size and gene content across evolutionarily closely as well as distantly related mammals. Although striking differences like those observed between human and mouse may be rare, variations similar to those seen between horse and human may be prevalent among mammals.
(c) 2008 S. Karger AG, Basel
Publication Date: 2008-06-09 PubMed ID: 18544933DOI: 10.1159/000125835Google Scholar: Lookup
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- Comparative Study
- Journal Article
Summary
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The research paper details the investigation carried out on a genomic segment, the pseudoautosomal region (PAR), in horse chromosomes. This study clarified this region’s characteristics, compared it to the PARs of humans, chimps, and mice, and proposed that the PAR may vary in size and gene content across different mammalian species.
Understanding the Pseudoautosomal Region (PAR)
- The pseudoautosomal region (PAR) is a portion of the genome located on sexual chromosomes. This segment displays sequence homology similar to that seen among autosomal homologues.
- The PAR plays a critical role in the pairing and proper separation of sex chromosomes during male meiosis, a process that leads to sperm formation.
- Before this study, only human/chimp and mouse PARs had been characterized, showing significant differences in gene content and size. These differences did not allow for valid assumptions about the evolution and composition of PARs across the mammalian kingdom.
Exploring the Equine PAR
- The researchers set out to analyze the equine (horse) PAR. Their approach included isolating and arranging 71 BACs (a method used in genetics to isolate DNA fragments), which contained 129 markers. Those markers were arranged into two contiguous series spanning the genomic region in question.
- The team also precisely identified the pseudoautosomal boundary (PAB), which marks where the PAR ends and the X- and Y-specific areas begin.
- The study further detailed parts of the X- and Y-specific regions adjacent to the PAR.
New Findings and Comparisons
- One unique discovery was the finding of a roughly 200 kb region within the equine PAR that is also present in the male-specific region of the Y chromosome (MSY). This kind of duplication had not been observed in mammals before.
- Comparisons between the horse PAR and the human PAR revealed size differences. Even though the horse PAR contained orthologs (genes in different species that evolved from a common ancestral gene) from a region 1 million base pairs (1 Mb) larger than the human equivalent (PAR1), the horse PAR was about 0.9 million base pairs smaller overall.
Conclusions and Theories about PAR Evolution
- This study suggests that the PAR size and gene content might be different across mammalian species, whether these species are distantly or closely related in evolutionary terms. This significant variability was seen between humans and mice, as well as between humans and horses.
- The researchers opine that large differences, as seen between humans and mice, might be unusual. However, variations similar to those observed between humans and horses might be more common across mammalian species.
Cite This Article
APA
Raudsepp T, Chowdhary BP.
(2008).
The horse pseudoautosomal region (PAR): characterization and comparison with the human, chimp and mouse PARs.
Cytogenet Genome Res, 121(2), 102-109.
https://doi.org/10.1159/000125835 Publication
Researcher Affiliations
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843-4458, USA. traudsepp@cvm.tamu.edu
MeSH Terms
- Animals
- Base Composition
- Chromosomes, Artificial, Bacterial / genetics
- Chromosomes, Human, X / genetics
- Chromosomes, Human, Y / genetics
- Contig Mapping
- DNA / genetics
- Evolution, Molecular
- Gene Duplication
- Horses / genetics
- Humans
- In Situ Hybridization, Fluorescence
- Male
- Meiosis / genetics
- Mice
- Radiation Hybrid Mapping
- Species Specificity
- X Chromosome / genetics
- Y Chromosome / genetics
Citations
This article has been cited 23 times.- Rossetti C, Genualdo V, Incarnato D, Mottola F, Perucatti A, Pauciullo A. State of the art on the physical mapping of the Y-chromosome in the Bovidae and comparison with other species - A review. Anim Biosci 2022 Sep;35(9):1289-1302.
- Castaneda C, Ruiz AJ, Tibary A, Raudsepp T. Molecular Cytogenetic and Y Copy Number Analysis of a Reciprocal ECAY-ECA13 Translocation in a Stallion with Complete Meiotic Arrest. Genes (Basel) 2021 Nov 26;12(12).
- Janssenswillen S, Roelants K, Carpentier S, de Rooster H, Metzemaekers M, Vanschoenwinkel B, Proost P, Bossuyt F. Odorant-binding proteins in canine anal sac glands indicate an evolutionarily conserved role in mammalian chemical communication. BMC Ecol Evol 2021 Sep 26;21(1):182.
- Krasovec M, Zhang Y, Filatov DA. The Location of the Pseudoautosomal Boundary in Silene latifolia. Genes (Basel) 2020 May 31;11(6).
- Janečka JE, Davis BW, Ghosh S, Paria N, Das PJ, Orlando L, Schubert M, Nielsen MK, Stout TAE, Brashear W, Li G, Johnson CD, Metz RP, Zadjali AMA, Love CC, Varner DD, Bellott DW, Murphy WJ, Chowdhary BP, Raudsepp T. Horse Y chromosome assembly displays unique evolutionary features and putative stallion fertility genes. Nat Commun 2018 Jul 27;9(1):2945.
- Ma Q, Liu X, Pan J, Ma L, Ma Y, He X, Zhao Q, Pu Y, Li Y, Jiang L. Genome-wide detection of copy number variation in Chinese indigenous sheep using an ovine high-density 600 K SNP array. Sci Rep 2017 Apr 19;7(1):912.
- Rafati N, Andersson LS, Mikko S, Feng C, Raudsepp T, Pettersson J, Janecka J, Wattle O, Ameur A, Thyreen G, Eberth J, Huddleston J, Malig M, Bailey E, Eichler EE, Dalin G, Chowdary B, Andersson L, Lindgren G, Rubin CJ. Large Deletions at the SHOX Locus in the Pseudoautosomal Region Are Associated with Skeletal Atavism in Shetland Ponies. G3 (Bethesda) 2016 Jul 7;6(7):2213-23.
- Cotter DJ, Brotman SM, Wilson Sayres MA. Genetic Diversity on the Human X Chromosome Does Not Support a Strict Pseudoautosomal Boundary. Genetics 2016 May;203(1):485-92.
- Hinch AG, Altemose N, Noor N, Donnelly P, Myers SR. Recombination in the human Pseudoautosomal region PAR1. PLoS Genet 2014 Jul;10(7):e1004503.
- Blackmon H, Demuth JP. Estimating tempo and mode of Y chromosome turnover: explaining Y chromosome loss with the fragile Y hypothesis. Genetics 2014 Jun;197(2):561-72.
- Cox KH, Bonthuis PJ, Rissman EF. Mouse model systems to study sex chromosome genes and behavior: relevance to humans. Front Neuroendocrinol 2014 Oct;35(4):405-19.
- Chitko-McKown CG, Chapes SK, Miller LC, Riggs PK, Ortega MT, Green BT, McKown RD. Development and characterization of two porcine monocyte-derived macrophage cell lines. Results Immunol 2013;3:26-32.
- Skinner BM, Lachani K, Sargent CA, Affara NA. Regions of XY homology in the pig X chromosome and the boundary of the pseudoautosomal region. BMC Genet 2013 Jan 15;14:3.
- Avila F, Das PJ, Kutzler M, Owens E, Perelman P, Rubes J, Hornak M, Johnson WE, Raudsepp T. Development and application of camelid molecular cytogenetic tools. J Hered 2014 Nov-Dec;105(6):858-69.
- White MA, Ikeda A, Payseur BA. A pronounced evolutionary shift of the pseudoautosomal region boundary in house mice. Mamm Genome 2012 Aug;23(7-8):454-66.
- Blavet N, Blavet H, Cegan R, Zemp N, Zdanska J, Janoušek B, Hobza R, Widmer A. Comparative analysis of a plant pseudoautosomal region (PAR) in Silene latifolia with the corresponding S. vulgaris autosome. BMC Genomics 2012 Jun 8;13:226.
- Doan R, Cohen ND, Sawyer J, Ghaffari N, Johnson CD, Dindot SV. Whole-genome sequencing and genetic variant analysis of a Quarter Horse mare. BMC Genomics 2012 Feb 17;13:78.
- Paria N, Raudsepp T, Pearks Wilkerson AJ, O'Brien PC, Ferguson-Smith MA, Love CC, Arnold C, Rakestraw P, Murphy WJ, Chowdhary BP. A gene catalogue of the euchromatic male-specific region of the horse Y chromosome: comparison with human and other mammals. PLoS One 2011;6(7):e21374.
- Janes DE, Valenzuela N, Ezaz T, Amemiya C, Edwards SV. Sex chromosome evolution in amniotes: applications for bacterial artificial chromosome libraries. J Biomed Biotechnol 2011;2011:132975.
- Delgado CL, Waters PD, Gilbert C, Robinson TJ, Graves JA. Physical mapping of the elephant X chromosome: conservation of gene order over 105 million years. Chromosome Res 2009;17(7):917-26.
- Young AC, Kirkness EF, Breen M. Tackling the characterization of canine chromosomal breakpoints with an integrated in-situ/in-silico approach: the canine PAR and PAB. Chromosome Res 2008;16(8):1193-202.
- Valera M, Karlau A, Anaya G, Bugno-Poniewierska M, Molina A, Encina A, Azor PJ, Demyda-Peyrás S. The Use of Genomic Screening for the Detection of Chromosomal Abnormalities in the Domestic Horse: Five New Cases of 65,XXY Syndrome in the Pura Raza Español Breed. Animals (Basel) 2024 Sep 3;14(17).
- Jevit MJ, Castaneda C, Paria N, Das PJ, Miller D, Antczak DF, Kalbfleisch TS, Davis BW, Raudsepp T. Trio-binning of a hinny refines the comparative organization of the horse and donkey X chromosomes and reveals novel species-specific features. Sci Rep 2023 Nov 17;13(1):20180.
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