Gene Duplication and Fragmentation in the Zebra Finch Major Histocompatibility Complex

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Gene Duplication and Fragmentation in the Zebra Finch Major Histocompatibility Complex

Show simple item record Balakrishnan, Christopher N Ekblom, Robert Völker, Martin Westerdahl, Helena Kotkiewicz, Holly Burt, David W Graves, Tina Griffin, Darren K Warren, Wesley C Godinez, Ricardo Edwards, Scott V. 2010-09-30T17:37:23Z 2010
dc.identifier.citation Balakrishnan, Christopher N., Robert Ekblom, Martin Völker, Helena Westerdahl, Ricardo Godinez, Holly Kotkiewicz, David W. Burt, et al. 2010. Gene duplication and fragmentation in the zebra finch major histocompatibility complex. BMC Biology 8:29. en_US
dc.identifier.issn 1741-7007 en_US
dc.description.abstract Background: Due to its high polymorphism and importance for disease resistance, the major histocompatibility complex (MHC) has been an important focus of many vertebrate genome projects. Avian MHC organization is of particular interest because the chicken Gallus gallus, the avian species with the best characterized MHC, possesses a highly streamlined minimal essential MHC, which is linked to resistance against specific pathogens. It remains unclear the extent to which this organization describes the situation in other birds and whether it represents a derived or ancestral condition. The sequencing of the zebra finch Taeniopygia guttata genome, in combination with targeted bacterial artificial chromosome (BAC) sequencing, has allowed us to characterize an MHC from a highly divergent and diverse avian lineage, the passerines. Results: The zebra finch MHC exhibits a complex structure and history involving gene duplication and fragmentation. The zebra finch MHC includes multiple Class I and Class II genes, some of which appear to be pseudogenes, and spans a much more extensive genomic region than the chicken MHC, as evidenced by the presence of MHC genes on each of seven BACs spanning 739 kb. Cytogenetic (FISH) evidence and the genome assembly itself place core MHC genes on as many as four chromosomes with TAP and Class I genes mapping to different chromosomes. MHC Class II regions are further characterized by high endogenous retroviral content. Lastly, we find strong evidence of selection acting on sites within passerine MHC Class I and Class II genes. Conclusion: The zebra finch MHC differs markedly from that of the chicken, the only other bird species with a complete genome sequence. The apparent lack of synteny between TAP and the expressed MHC Class I locus is in fact reminiscent of a pattern seen in some mammalian lineages and may represent convergent evolution. Our analyses of the zebra finch MHC suggest a complex history involving chromosomal fission, gene duplication and translocation in the history of the MHC in birds, and highlight striking differences in MHC structure and organization among avian lineages. en_US
dc.description.sponsorship Organismic and Evolutionary Biology en_US
dc.language.iso en_US en_US
dc.publisher BioMed Central en_US
dc.relation.isversionof doi:10.1186/1741-7007-8-29 en_US
dc.relation.hasversion en_US
dash.license OAP
dc.title Gene Duplication and Fragmentation in the Zebra Finch Major Histocompatibility Complex en_US
dc.type Journal Article en_US
dc.description.version Version of Record en_US
dc.relation.journal BMC Biology en_US Edwards, Scott V. 2010-09-30T17:37:23Z

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