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Trebes H, Wang Y, Reynolds E, Tiplady K, Harland C, Lopdell T, Johnson T, Davis S, Harris B, Spelman R, Couldrey C. Identification of candidate novel production variants on the Bos taurus chromosome X. J Dairy Sci 2023; 106:7799-7815. [PMID: 37562645 DOI: 10.3168/jds.2022-23095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 04/26/2023] [Indexed: 08/12/2023]
Abstract
Chromosome X is often excluded from bovine genetic studies due to complications caused by the sex specific nature of the chromosome. As chromosome X is the second largest cattle chromosome and makes up approximately 6% of the female genome, finding ways to include chromosome X in dairy genetic studies is important. Using female animals and treating chromosome X as an autosome, we performed X chromosome inclusive genome-wide association studies in the selective breeding environment of the New Zealand dairy industry, aiming to identify chromosome X variants associated with milk production traits. We report on the findings of these genome-wide association studies and their potential effect within the dairy industry. We identify missense mutations in the MOSPD1 and CCDC160 genes that are associated with decreased milk volume and protein production and increased fat production. Both of these mutations are exonic SNP that are more prevalent in the Jersey breed than in Holstein-Friesians. Of the 2 candidates proposed it is likely that only one is causal, though we have not been able to identify which is more likely.
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Affiliation(s)
- H Trebes
- Research and Development, Livestock Improvement Corporation, Hamilton 3240, New Zealand.
| | - Y Wang
- Research and Development, Livestock Improvement Corporation, Hamilton 3240, New Zealand
| | - E Reynolds
- Research and Development, Livestock Improvement Corporation, Hamilton 3240, New Zealand
| | - K Tiplady
- Research and Development, Livestock Improvement Corporation, Hamilton 3240, New Zealand
| | - C Harland
- Research and Development, Livestock Improvement Corporation, Hamilton 3240, New Zealand
| | - T Lopdell
- Research and Development, Livestock Improvement Corporation, Hamilton 3240, New Zealand
| | - T Johnson
- Research and Development, Livestock Improvement Corporation, Hamilton 3240, New Zealand
| | - S Davis
- Research and Development, Livestock Improvement Corporation, Hamilton 3240, New Zealand
| | - B Harris
- Research and Development, Livestock Improvement Corporation, Hamilton 3240, New Zealand
| | - R Spelman
- Research and Development, Livestock Improvement Corporation, Hamilton 3240, New Zealand
| | - C Couldrey
- Research and Development, Livestock Improvement Corporation, Hamilton 3240, New Zealand
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2
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Sanchez MP, Escouflaire C, Baur A, Bottin F, Hozé C, Boussaha M, Fritz S, Capitan A, Boichard D. X-linked genes influence various complex traits in dairy cattle. BMC Genomics 2023; 24:338. [PMID: 37337145 DOI: 10.1186/s12864-023-09438-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 06/08/2023] [Indexed: 06/21/2023] Open
Abstract
BACKGROUND The search for quantitative trait loci (QTL) affecting traits of interest in mammals is frequently limited to autosomes, with the X chromosome excluded because of its hemizygosity in males. This study aimed to assess the importance of the X chromosome in the genetic determinism of 11 complex traits related to milk production, milk composition, mastitis resistance, fertility, and stature in 236,496 cows from three major French dairy breeds (Holstein, Montbéliarde, and Normande) and three breeds of regional importance (Abondance, Tarentaise, and Vosgienne). RESULTS Estimates of the proportions of heritability due to autosomes and X chromosome (h²X) were consistent among breeds. On average over the 11 traits, h²X=0.008 and the X chromosome explained ~ 3.5% of total genetic variance. GWAS was performed within-breed at the sequence level (~ 200,000 genetic variants) and then combined in a meta-analysis. QTL were identified for most breeds and traits analyzed, with the exception of Tarentaise and Vosgienne and two fertility traits. Overall, 3, 74, 59, and 71 QTL were identified in Abondance, Montbéliarde, Normande, and Holstein, respectively, and most were associated with the most-heritable traits (milk traits and stature). The meta-analyses, which assessed a total of 157 QTL for the different traits, highlighted new QTL and refined the positions of some QTL found in the within-breed analyses. Altogether, our analyses identified a number of functional candidate genes, with the most notable being GPC3, MBNL3, HS6ST2, and DMD for dairy traits; TMEM164, ACSL4, ENOX2, HTR2C, AMOT, and IRAK1 for udder health; MAMLD1 and COL4A6 for fertility; and NRK, ESX1, GPR50, GPC3, and GPC4 for stature. CONCLUSIONS This study demonstrates the importance of the X chromosome in the genetic determinism of complex traits in dairy cattle and highlights new functional candidate genes and variants for these traits. These results could potentially be extended to other species as many X-linked genes are shared among mammals.
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Affiliation(s)
- Marie-Pierre Sanchez
- Université Paris-Saclay, INRAE, AgroParisTech, GABI, Jouy-en-Josas, 78350, France.
| | | | | | - Fiona Bottin
- Université Paris-Saclay, INRAE, AgroParisTech, GABI, Jouy-en-Josas, 78350, France
| | | | - Mekki Boussaha
- Université Paris-Saclay, INRAE, AgroParisTech, GABI, Jouy-en-Josas, 78350, France
| | | | - Aurélien Capitan
- Université Paris-Saclay, INRAE, AgroParisTech, GABI, Jouy-en-Josas, 78350, France
| | - Didier Boichard
- Université Paris-Saclay, INRAE, AgroParisTech, GABI, Jouy-en-Josas, 78350, France
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3
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Id-Lahoucine S, Casellas J, Fonseca PAS, Suárez-Vega A, Schenkel FS, Cánovas A. Deviations from Mendelian Inheritance on Bovine X-Chromosome Revealing Recombination, Sex-of-Offspring Effects and Fertility-Related Candidate Genes. Genes (Basel) 2022; 13:genes13122322. [PMID: 36553588 PMCID: PMC9778079 DOI: 10.3390/genes13122322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 12/05/2022] [Accepted: 12/06/2022] [Indexed: 12/14/2022] Open
Abstract
Transmission ratio distortion (TRD), or significant deviations from Mendelian inheritance, is a well-studied phenomenon on autosomal chromosomes, but has not yet received attention on sex chromosomes. TRD was analyzed on 3832 heterosomal single nucleotide polymorphisms (SNPs) and 400 pseudoautosomal SNPs spanning the length of the X-chromosome using 436,651 genotyped Holstein cattle. On the pseudoautosomal region, an opposite sire-TRD pattern between male and female offspring was identified for 149 SNPs. This finding revealed unique SNPs linked to a specific-sex (Y- or X-) chromosome and describes the accumulation of recombination events across the pseudoautosomal region. On the heterosomal region, 13 SNPs and 69 haplotype windows were identified with dam-TRD. Functional analyses for TRD regions highlighted relevant biological functions responsible to regulate spermatogenesis, development of Sertoli cells, homeostasis of endometrium tissue and embryonic development. This study uncovered the prevalence of different TRD patterns across both heterosomal and pseudoautosomal regions of the X-chromosome and revealed functional candidate genes for bovine reproduction.
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Affiliation(s)
- Samir Id-Lahoucine
- Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Joaquim Casellas
- Departament de Ciència Animal i dels Aliments, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Pablo A. S. Fonseca
- Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Aroa Suárez-Vega
- Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Flavio S. Schenkel
- Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Angela Cánovas
- Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON N1G 2W1, Canada
- Correspondence:
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4
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Effect of genomic X-chromosome regions on Nelore bull fertility. J Appl Genet 2021; 62:655-659. [PMID: 34145524 DOI: 10.1007/s13353-021-00645-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 06/07/2021] [Accepted: 06/10/2021] [Indexed: 10/21/2022]
Abstract
Scrotal circumference (SC) is a commonly used trait related to sexual precocity in bulls. Genome-wide association studies have uncovered a lot of genes related to this trait, however, only those present on autosomes. The inclusion of the second biggest chromosome (BTAX) can improve the knowledge of the genetic architecture of this trait. In this study, we performed a weighted, single-step, genome-wide association study using a 777 k BovineHD BeadChip (IllumHD) to analyze the association between SNPs and SC in Brazilian Nelore cattle. Phenotypes from 79,300 males and 3263 genotypes (2017 from females and 1246 from males)-(39,367 SNPs markers located at ChrX) were used. We identified eight regions on chromosome X that displayed important associations with SC. The results showed that together the genomic windows explained 28.52% of the genetic variance for the examined trait. Genes with potential functions in reproduction and fertility regulation were highlighted as candidates for sexual precocity rates in Nelore cattle (AFF2 and PJA1). Moreover, we found 10 genes that had not previously been identified as being associated with sexual precocity traits in cattle. These findings will further advance our understanding of the genetic architecture, considering mainly the presence of the chromosome X, for indicine cattle reproductive traits, being useful in the context of genomic prediction in beef cattle.
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5
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Balaton BP, Fornes O, Wasserman WW, Brown CJ. Cross-species examination of X-chromosome inactivation highlights domains of escape from silencing. Epigenetics Chromatin 2021; 14:12. [PMID: 33597016 PMCID: PMC7890635 DOI: 10.1186/s13072-021-00386-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 02/01/2021] [Indexed: 12/14/2022] Open
Abstract
Background X-chromosome inactivation (XCI) in eutherian mammals is the epigenetic inactivation of one of the two X chromosomes in XX females in order to compensate for dosage differences with XY males. Not all genes are inactivated, and the proportion escaping from inactivation varies between human and mouse (the two species that have been extensively studied). Results We used DNA methylation to predict the XCI status of X-linked genes with CpG islands across 12 different species: human, chimp, bonobo, gorilla, orangutan, mouse, cow, sheep, goat, pig, horse and dog. We determined the XCI status of 342 CpG islands on average per species, with most species having 80–90% of genes subject to XCI. Mouse was an outlier, with a higher proportion of genes subject to XCI than found in other species. Sixteen genes were found to have discordant X-chromosome inactivation statuses across multiple species, with five of these showing primate-specific escape from XCI. These discordant genes tended to cluster together within the X chromosome, along with genes with similar patterns of escape from XCI. CTCF-binding, ATAC-seq signal and LTR repeats were enriched at genes escaping XCI when compared to genes subject to XCI; however, enrichment was only observed in three or four of the species tested. LINE and DNA repeats showed enrichment around subject genes, but again not in a consistent subset of species. Conclusions In this study, we determined XCI status across 12 species, showing mouse to be an outlier with few genes that escape inactivation. Inactivation status is largely conserved across species. The clustering of genes that change XCI status across species implicates a domain-level control. In contrast, the relatively consistent, but not universal correlation of inactivation status with enrichment of repetitive elements or CTCF binding at promoters demonstrates gene-based influences on inactivation state. This study broadens enrichment analysis of regulatory elements to species beyond human and mouse.
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Affiliation(s)
- Bradley P Balaton
- Department of Medical Genetics, The University of British Columbia, Vancouver, Canada
| | - Oriol Fornes
- Department of Medical Genetics, The University of British Columbia, Vancouver, Canada.,BC Children's Hospital Research Institute, Vancouver, Canada.,Centre for Molecular Medicine and Therapeutics, The University of British Columbia, Vancouver, Canada
| | - Wyeth W Wasserman
- Department of Medical Genetics, The University of British Columbia, Vancouver, Canada.,BC Children's Hospital Research Institute, Vancouver, Canada.,Centre for Molecular Medicine and Therapeutics, The University of British Columbia, Vancouver, Canada
| | - Carolyn J Brown
- Department of Medical Genetics, The University of British Columbia, Vancouver, Canada.
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6
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Del Pilar Solar Diaz I, de Camargo GMF, Rocha da Cruz VA, da Costa Hermisdorff I, Carvalho CVD, de Albuquerque LG, Costa RB. Effect of the X chromosome in genomic evaluations of reproductive traits in beef cattle. Anim Reprod Sci 2020; 225:106682. [PMID: 33360620 DOI: 10.1016/j.anireprosci.2020.106682] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Revised: 12/14/2020] [Accepted: 12/15/2020] [Indexed: 01/19/2023]
Abstract
The aim of this study was to evaluate whether there are predictive advantages for breeding values with inclusion of X chromosome genomic markers for reproductive (occurrence of early pregnancy - P16 and age at first calving - AFC) and andrological (scrotal circumference -SC) variables in beef cattle. There were 3263 genotypes of females and males evaluated. There were breeding value estimates for SC, AFC and P16 considering two scenarios: 1) only autosomal markers or 2) autosomal and X chromosome markers. To evaluate effects of inclusion of X chromosome markers on selection, responses to selection were compared including or not including genomic marker information from the X chromosome. There were greater heritability estimates for SC (0.40 and 0.31), AFC (0.11 and 0.09) and P16 (0.43 and 0.38) when analyses included, compared with not including, genomic marker information from the X chromosome. When selection is based on results from analyses that did not include information for the X chromosome, there was about a 7 % lesser mean genomic breeding value for the SC traits for selected animals. For P16, there was an approximate 4% lesser breeding value without inclusion of genomic marker information from the X chromosome, while this inclusion did not have as great an effect on the breeding value for AFC. There was an average predictive correlation of 0.79, 0.98 and 0.84 for SC, AFC and P16, respectively. These estimates indicate inclusion of the X chromosome genomic marker information in the analysis can improve prediction of genomic breeding values, especially for SC.
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Affiliation(s)
- Iara Del Pilar Solar Diaz
- Escola de Medicina Veterinária e Zootecnia, Universidade Federal da Bahia (UFBA), 40170-110, Salvador, BA, Brazil
| | | | | | - Isis da Costa Hermisdorff
- Escola de Medicina Veterinária e Zootecnia, Universidade Federal da Bahia (UFBA), 40170-110, Salvador, BA, Brazil
| | | | - Lucia Galvão de Albuquerque
- Departamento de Zootecnia, Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista (Unesp), Jaboticabal, SP, Brazil
| | - Raphael Bermal Costa
- Escola de Medicina Veterinária e Zootecnia, Universidade Federal da Bahia (UFBA), 40170-110, Salvador, BA, Brazil.
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7
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Diaz IDPS, de Camargo GMF, Cruz VARD, Hermisdorff IDC, Carvalho CVD, de Albuquerque LG, Costa RB. Mapping genomic regions for reproductive traits in beef cattle: Inclusion of the X chromosome. Reprod Domest Anim 2020; 55:1650-1654. [PMID: 32853424 DOI: 10.1111/rda.13810] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 08/19/2020] [Indexed: 12/15/2022]
Abstract
Although the second largest chromosome of the genome, the X chromosome is usually excluded from genome-wide association studies (GWAS). Considering the presence and importance of genes on this chromosome that are involved in reproduction, the aim of this study was to evaluate the effect of its inclusion in GWAS on reproductive traits (scrotal circumference [SC], early pregnancy [P16] and age at first calving [AFC]) in a Nelore herd. Genotype data from 3,263 animals with the above-mentioned phenotypes were used. The results showed an increase in the variances explained by the autosomal markers for all traits when the X chromosome was not included. For SC, there was an increase of more than 10% for the windows on chromosomes 2 and 6. For P16, the effect was increased by almost 20% for windows on chromosome 5. The same pattern was found for AFC, with an increase of more than 10% for the most important windows. The results indicate that the noninclusion of the X chromosome can overestimate the effects of autosomes on SC, P16 and AFC not only because of the additive effect of the X chromosome itself but also because of its epistatic effect on autosomal genes.
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Affiliation(s)
| | | | | | | | | | - Lucia Galvão de Albuquerque
- Departamento de Zootecnia, Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista (Unesp), Jaboticabal, Brazil
| | - Raphael Bermal Costa
- Escola de Medicina Veterinária e Zootecnia, Universidade Federal da Bahia (UFBA), Salvador, Brazil
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8
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Lamb HJ, Ross EM, Nguyen LT, Lyons RE, Moore SS, Hayes BJ. Characterization of the poll allele in Brahman cattle using long-read Oxford Nanopore sequencing. J Anim Sci 2020; 98:5823688. [PMID: 32318708 DOI: 10.1093/jas/skaa127] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 04/20/2020] [Indexed: 12/13/2022] Open
Abstract
Brahman cattle (Bos indicus) are well adapted to thrive in tropical environments. Since their introduction to Australia in 1933, Brahman's ability to grow and reproduce on marginal lands has proven their value in the tropical beef industry. The poll phenotype, which describes the absence of horns, has become desirable in the cattle industry for animal welfare and handler safety concerns. The poll locus has been mapped to chromosome one. Four alleles, each a copy number variant, have been reported across this locus in B. indicus and Bos taurus. However, the causative mutation in Brahman cattle has not been fully characterized. Oxford Nanopore Technologies' minION sequencer was used to sequence four homozygous poll (PcPc), four homozygous horned (pp), and three heterozygous (Pcp) Brahmans to characterize the poll allele in Brahman cattle. A total of 98 Gb were sequenced and an average coverage of 3.33X was achieved. Read N50 scores ranged from 9.9 to 19 kb. Examination of the mapped reads across the poll locus revealed insertions approximately 200 bp in length in the poll animals that were absent in the horned animals. These results are consistent with the Celtic poll allele, a 212-bp duplication that replaces 10 bp. This provides direct evidence that the Celtic poll allele is segregating in the Australian Brahman population.
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Affiliation(s)
- Harrison J Lamb
- Centre for Animal Science, Queensland Alliance for Agriculture and Food Innovation, University of Queensland, St Lucia, QLD, Australia
| | - Elizabeth M Ross
- Centre for Animal Science, Queensland Alliance for Agriculture and Food Innovation, University of Queensland, St Lucia, QLD, Australia
| | - Loan T Nguyen
- Centre for Animal Science, Queensland Alliance for Agriculture and Food Innovation, University of Queensland, St Lucia, QLD, Australia
| | - Russell E Lyons
- Neogen Australasia, University of Queensland, Gatton, QLD, Australia
| | - Stephen S Moore
- Centre for Animal Science, Queensland Alliance for Agriculture and Food Innovation, University of Queensland, St Lucia, QLD, Australia
| | - Ben J Hayes
- Centre for Animal Science, Queensland Alliance for Agriculture and Food Innovation, University of Queensland, St Lucia, QLD, Australia
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9
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Posynick BJ, Brown CJ. Escape From X-Chromosome Inactivation: An Evolutionary Perspective. Front Cell Dev Biol 2019; 7:241. [PMID: 31696116 PMCID: PMC6817483 DOI: 10.3389/fcell.2019.00241] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 10/02/2019] [Indexed: 12/14/2022] Open
Abstract
Sex chromosomes originate as a pair of homologus autosomes that then follow a general pattern of divergence. This is evident in mammalian sex chromosomes, which have undergone stepwise recombination suppression events that left footprints of evolutionary strata on the X chromosome. The loss of genes on the Y chromosome led to Ohno’s hypothesis of dosage equivalence between XY males and XX females, which is achieved through X-chromosome inactivation (XCI). This process transcriptionally silences all but one X chromosome in each female cell, although 15–30% of human X-linked genes still escape inactivation. There are multiple evolutionary pathways that may lead to a gene escaping XCI, including remaining Y chromosome homology, or female advantage to escape. The conservation of some escape genes across multiple species and the ability of the mouse inactive X to recapitulate human escape status both suggest that escape from XCI is controlled by conserved processes. Evolutionary pressures to minimize dosage imbalances have led to the accumulation of genetic elements that favor either silencing or escape; lack of dosage sensitivity might also allow for the escape of flanking genes near another escapee, if a boundary element is not present between them. Delineation of the elements involved in escape is progressing, but mechanistic understanding of how they interact to allow escape from XCI is still lacking. Although increasingly well-studied in humans and mice, non-trivial challenges to studying escape have impeded progress in other species. Mouse models that can dissect the role of the sex chromosomes distinct from sex of the organism reveal an important contribution for escape genes to multiple diseases. In humans, with their elevated number of escape genes, the phenotypic consequences of sex chromosome aneuplodies and sexual dimorphism in disease both highlight the importance of escape genes.
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Affiliation(s)
- Bronwyn J Posynick
- Department of Medical Genetics, Molecular Epigenetics Group, Life Sciences Institute, The University of British Columbia, Vancouver, BC, Canada
| | - Carolyn J Brown
- Department of Medical Genetics, Molecular Epigenetics Group, Life Sciences Institute, The University of British Columbia, Vancouver, BC, Canada
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10
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Carvalho CVD, Hermisdorff IDC, Souza IS, Junqueira GSB, Magalhães AFB, Fonseca LFS, de Albuquerque LG, Tonhati H, Carvalheiro R, de Camargo GMF, Costa RB. Influence of X-chromosome markers on reproductive traits of beef cattle. Livest Sci 2019. [DOI: 10.1016/j.livsci.2018.12.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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11
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Johnson T, Keehan M, Harland C, Lopdell T, Spelman RJ, Davis SR, Rosen BD, Smith TPL, Couldrey C. Short communication: Identification of the pseudoautosomal region in the Hereford bovine reference genome assembly ARS-UCD1.2. J Dairy Sci 2019; 102:3254-3258. [PMID: 30712931 DOI: 10.3168/jds.2018-15638] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Accepted: 12/04/2018] [Indexed: 11/19/2022]
Abstract
In cattle, the X chromosome accounts for approximately 3 and 6% of the genome in bulls and cows, respectively. In spite of the large size of this chromosome, very few studies report analysis of the X chromosome in genome-wide association studies and genomic selection. This lack of genetic interrogation is likely due to the complexities of undertaking these studies given the hemizygous state of some, but not all, of the X chromosome in males. The first step in facilitating analysis of this gene-rich chromosome is to accurately identify coordinates for the pseudoautosomal boundary (PAB) to split the chromosome into a region that may be treated as autosomal sequence (pseudoautosomal region) and a region that requires more complex statistical models. With the recent release of ARS-UCD1.2, a more complete and accurate assembly of the cattle genome than was previously available, it is timely to fine map the PAB for the first time. Here we report the use of SNP chip genotypes, short-read sequences, and long-read sequences to fine map the PAB (X chromosome:133,300,518) and simultaneously determine the neighboring regions of reduced homology and true pseudoautosomal region. These results greatly facilitate the inclusion of the X chromosome in genome-wide association studies, genomic selection, and other genetic analysis undertaken on this reference genome.
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Affiliation(s)
- T Johnson
- Research and Development, Livestock Improvement Corporation, Hamilton 3240, New Zealand
| | - M Keehan
- Research and Development, Livestock Improvement Corporation, Hamilton 3240, New Zealand
| | - C Harland
- Research and Development, Livestock Improvement Corporation, Hamilton 3240, New Zealand
| | - T Lopdell
- Research and Development, Livestock Improvement Corporation, Hamilton 3240, New Zealand
| | - R J Spelman
- Research and Development, Livestock Improvement Corporation, Hamilton 3240, New Zealand
| | - S R Davis
- Research and Development, Livestock Improvement Corporation, Hamilton 3240, New Zealand
| | - B D Rosen
- Animal Genomics and Improvement Laboratory, Agricultural Research Service USDA, Beltsville, MD 20705
| | - T P L Smith
- US Meat Animal Research Center, Agricultural Research Service USDA, Clay Center, NE 68933
| | - C Couldrey
- Research and Development, Livestock Improvement Corporation, Hamilton 3240, New Zealand.
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12
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Duan JE, Shi W, Jue NK, Jiang Z, Kuo L, O'Neill R, Wolf E, Dong H, Zheng X, Chen J, Tian XC. Dosage Compensation of the X Chromosomes in Bovine Germline, Early Embryos, and Somatic Tissues. Genome Biol Evol 2019; 11:242-252. [PMID: 30566637 PMCID: PMC6354180 DOI: 10.1093/gbe/evy270] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/12/2018] [Indexed: 12/15/2022] Open
Abstract
Dosage compensation of the mammalian X chromosome (X) was proposed by Susumu Ohno as a mechanism wherein the inactivation of one X in females would lead to doubling the expression of the other. This would resolve the dosage imbalance between eutherian females (XX) versus male (XY) and between a single active X versus autosome pairs (A). Expression ratio of X- and A-linked genes has been relatively well studied in humans and mice, despite controversial results over the existence of upregulation of X-linked genes. Here we report the first comprehensive test of Ohno’s hypothesis in bovine preattachment embryos, germline, and somatic tissues. Overall an incomplete dosage compensation (0.5 < X:A < 1) of expressed genes and an excess X dosage compensation (X:A > 1) of ubiquitously expressed “dosage-sensitive” genes were seen. No significant differences in X:A ratios were observed between bovine female and male somatic tissues, further supporting Ohno’s hypothesis. Interestingly, preimplantation embryos manifested a unique pattern of X dosage compensation dynamics. Specifically, X dosage decreased after fertilization, indicating that the sperm brings in an inactive X to the matured oocyte. Subsequently, the activation of the bovine embryonic genome enhanced expression of X-linked genes and increased the X dosage. As a result, an excess compensation was exhibited from the 8-cell stage to the compact morula stage. The X dosage peaked at the 16-cell stage and stabilized after the blastocyst stage. Together, our findings confirm Ohno’s hypothesis of X dosage compensation in the bovine and extend it by showing incomplete and over-compensation for expressed and “dosage-sensitive” genes, respectively.
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Affiliation(s)
| | - Wei Shi
- Department of Statistics, University of Connecticut, Storrs, CT
| | - Nathaniel K Jue
- School of Natural Sciences, California State University, Monterey Bay, CA
| | - Zongliang Jiang
- School of Animal Science, Louisiana State University, Agricultural Center, Baton Rouge, LA
| | - Lynn Kuo
- Department of Statistics, University of Connecticut, Storrs, CT
| | - Rachel O'Neill
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT
| | - Eckhard Wolf
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität Muünchen, Germany
| | - Hong Dong
- Institute of Animal Science, Xinjiang Academy of Animal Sciences, Urumqi, Xinjiang, P.R. China
| | - Xinbao Zheng
- Institute of Animal Science, Xinjiang Academy of Animal Sciences, Urumqi, Xinjiang, P.R. China
| | - Jingbo Chen
- Institute of Animal Science, Xinjiang Academy of Animal Sciences, Urumqi, Xinjiang, P.R. China
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