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Type: Journal article
Title: Platypus globin genes and flanking loci suggest a new insertional model for beta-globin evolution in birds and mammals
Author: Patel, V.
Cooper, S.
Deakin, J.
Fulton, B.
Graves, T.
Warren, W.
Wilson, R.
Graves, J.
Citation: BMC Biology, 2008; 6(1):34-55
Publisher: BioMed Central Ltd.
Issue Date: 2008
ISSN: 1741-7007
Statement of
Vidushi S. Patel, Steven J.B. Cooper, Janine E. Deakin, Bob Fulton, Tina Graves, Wesley C. Warren, Richard K. Wilson and Jennifer A.M. Graves
Abstract: Background: 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 (Ornithorhynchus anatinus), to explore haemoglobin evolution at the stem of the mammalian radiation. Results: The platypus α-globin cluster (chromosome 21) contains embryonic and adult α- globin genes, a β-like ω-globin gene, and the GBY globin gene with homology to cytoglobin, arranged as 5'-ζ-ζ'-αD-α3-α2-α1-ω-GBY-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 MPG-C16orf35 and LUC7L, 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. Conclusion: We propose that α- and β-globin clusters evolved from an ancient MPG-C16orf35-α-β-GBY-LUC7L 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.
Keywords: Chromosomes, Artificial, Bacterial
DNA Transposable Elements
Blotting, Southern
In Situ Hybridization, Fluorescence
Cloning, Molecular
Polymerase Chain Reaction
Sequence Analysis, DNA
Evolution, Molecular
Multigene Family
Models, Genetic
Promoter Regions, Genetic
DOI: 10.1186/1741-7007-6-34
Appears in Collections:Aurora harvest
Earth and Environmental Sciences publications
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