Platypus globin genes and flanking loci suggest a new insertional model for beta-globin evolution in birds and mammals
<p>Abstract</p> <p>Background</p> <p>Vertebrate alpha (α)- and beta (β)-globin gene families exemplify the way in which genomes evolve to produce functional complexity. From tandem duplication of a single globin locus, the α- and β-globin clusters expanded, and then wer...
| Main Authors: | , , , , , , , |
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| Format: | Article |
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BMC
2008-07-01
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| Series: | BMC Biology |
| Online Access: | http://www.biomedcentral.com/1741-7007/6/34 |
| _version_ | 1811252066601926656 |
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| author | Warren Wesley C Graves Tina Fulton Bob Deakin Janine E Cooper Steven JB Patel Vidushi S Wilson Richard K Graves Jennifer AM |
| author_facet | Warren Wesley C Graves Tina Fulton Bob Deakin Janine E Cooper Steven JB Patel Vidushi S Wilson Richard K Graves Jennifer AM |
| author_sort | Warren Wesley C |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Background</p> <p>Vertebrate alpha (α)- and beta (β)-globin gene families exemplify the way in which genomes evolve to produce functional complexity. From tandem duplication of a single globin locus, the α- and β-globin clusters expanded, and then were separated onto different chromosomes. The previous finding of a fossil β-globin gene (ω) in the marsupial α-cluster, however, suggested that duplication of the α-β cluster onto two chromosomes, followed by lineage-specific gene loss and duplication, produced paralogous α- and β-globin clusters in birds and mammals. Here we analyse genomic data from an egg-laying monotreme mammal, the platypus (<it>Ornithorhynchus anatinus</it>), to explore haemoglobin evolution at the stem of the mammalian radiation.</p> <p>Results</p> <p>The platypus α-globin cluster (chromosome 21) contains embryonic and adult α- globin genes, a β-like ω-globin gene, and the <it>GBY </it>globin gene with homology to cytoglobin, arranged as 5'-ζ-ζ'-α<sup>D</sup>-α<sup>3</sup>-α<sup>2</sup>-α<sup>1</sup>-ω-<it>GBY</it>-3'. The platypus β-globin cluster (chromosome 2) contains single embryonic and adult globin genes arranged as 5'-ε-β-3'. Surprisingly, all of these globin genes were expressed in some adult tissues. Comparison of flanking sequences revealed that all jawed vertebrate α-globin clusters are flanked by <it>MPG</it>-<it>C16orf35 </it>and <it>LUC7L</it>, whereas all bird and mammal β-globin clusters are embedded in olfactory genes. Thus, the mammalian α- and β-globin clusters are orthologous to the bird α- and β-globin clusters respectively.</p> <p>Conclusion</p> <p>We propose that α- and β-globin clusters evolved from an ancient <it>MPG-C16orf35-α</it>-β-<it>GBY-LUC7L </it>arrangement 410 million years ago. A copy of the original β (represented by ω in marsupials and monotremes) was inserted into an array of olfactory genes before the amniote radiation (>315 million years ago), then duplicated and diverged to form orthologous clusters of β-globin genes with different expression profiles in different lineages.</p> |
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| spelling | doaj.art-70da566ed9cb444090367cc50c9df20d2022-12-22T03:25:13ZengBMCBMC Biology1741-70072008-07-01613410.1186/1741-7007-6-34Platypus globin genes and flanking loci suggest a new insertional model for beta-globin evolution in birds and mammalsWarren Wesley CGraves TinaFulton BobDeakin Janine ECooper Steven JBPatel Vidushi SWilson Richard KGraves Jennifer AM<p>Abstract</p> <p>Background</p> <p>Vertebrate alpha (α)- and beta (β)-globin gene families exemplify the way in which genomes evolve to produce functional complexity. From tandem duplication of a single globin locus, the α- and β-globin clusters expanded, and then were separated onto different chromosomes. The previous finding of a fossil β-globin gene (ω) in the marsupial α-cluster, however, suggested that duplication of the α-β cluster onto two chromosomes, followed by lineage-specific gene loss and duplication, produced paralogous α- and β-globin clusters in birds and mammals. Here we analyse genomic data from an egg-laying monotreme mammal, the platypus (<it>Ornithorhynchus anatinus</it>), to explore haemoglobin evolution at the stem of the mammalian radiation.</p> <p>Results</p> <p>The platypus α-globin cluster (chromosome 21) contains embryonic and adult α- globin genes, a β-like ω-globin gene, and the <it>GBY </it>globin gene with homology to cytoglobin, arranged as 5'-ζ-ζ'-α<sup>D</sup>-α<sup>3</sup>-α<sup>2</sup>-α<sup>1</sup>-ω-<it>GBY</it>-3'. The platypus β-globin cluster (chromosome 2) contains single embryonic and adult globin genes arranged as 5'-ε-β-3'. Surprisingly, all of these globin genes were expressed in some adult tissues. Comparison of flanking sequences revealed that all jawed vertebrate α-globin clusters are flanked by <it>MPG</it>-<it>C16orf35 </it>and <it>LUC7L</it>, whereas all bird and mammal β-globin clusters are embedded in olfactory genes. Thus, the mammalian α- and β-globin clusters are orthologous to the bird α- and β-globin clusters respectively.</p> <p>Conclusion</p> <p>We propose that α- and β-globin clusters evolved from an ancient <it>MPG-C16orf35-α</it>-β-<it>GBY-LUC7L </it>arrangement 410 million years ago. A copy of the original β (represented by ω in marsupials and monotremes) was inserted into an array of olfactory genes before the amniote radiation (>315 million years ago), then duplicated and diverged to form orthologous clusters of β-globin genes with different expression profiles in different lineages.</p>http://www.biomedcentral.com/1741-7007/6/34 |
| spellingShingle | Warren Wesley C Graves Tina Fulton Bob Deakin Janine E Cooper Steven JB Patel Vidushi S Wilson Richard K Graves Jennifer AM Platypus globin genes and flanking loci suggest a new insertional model for beta-globin evolution in birds and mammals BMC Biology |
| title | Platypus globin genes and flanking loci suggest a new insertional model for beta-globin evolution in birds and mammals |
| title_full | Platypus globin genes and flanking loci suggest a new insertional model for beta-globin evolution in birds and mammals |
| title_fullStr | Platypus globin genes and flanking loci suggest a new insertional model for beta-globin evolution in birds and mammals |
| title_full_unstemmed | Platypus globin genes and flanking loci suggest a new insertional model for beta-globin evolution in birds and mammals |
| title_short | Platypus globin genes and flanking loci suggest a new insertional model for beta-globin evolution in birds and mammals |
| title_sort | platypus globin genes and flanking loci suggest a new insertional model for beta globin evolution in birds and mammals |
| url | http://www.biomedcentral.com/1741-7007/6/34 |
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