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Characterization of a nonclassical class I MHC gene in a reptile, the Galapagos marine iguana (Amblyrhynchus cristatus)

Glaberman, S. and Du Pasquier, L. and Caccone, A.. (2009) Characterization of a nonclassical class I MHC gene in a reptile, the Galapagos marine iguana (Amblyrhynchus cristatus). PLoS ONE, Vol. 3, H. 8 , e2859.

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Official URL: http://edoc.unibas.ch/dok/A5252615

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Abstract

Squamates are a diverse order of vertebrates, representing more than 7,000 species. Yet, descriptions of full-length major histocompatibility complex (MHC) genes in this group are nearly absent from the literature, while the number of MHC studies continues to rise in other vertebrate taxa. The lack of basic information about MHC organization in squamates inhibits investigation into the relationship between MHC polymorphism and disease, and leaves a large taxonomic gap in our understanding of amniote MHC evolution. Here, we use both cDNA and genomic sequence data to characterize a class I MHC gene (Amcr-UA) from the Gala´pagos marine iguana, a member of the squamate subfamily Iguaninae. Amcr-UA appears to be functional since it is expressed in the blood and contains many of the conserved peptide-binding residues that are found in classical class I genes of other vertebrates. In addition, comparison of Amcr-UA to homologous sequences from other iguanine species shows that the antigen-binding portion of this gene is under purifying selection, rather than balancing selection, and therefore may have a conserved function. A striking feature of Amcr-UA is that both the cDNA and genomic sequences lack the transmembrane and cytoplasmic domains that are necessary to anchor the class I receptor molecule into the cell membrane, suggesting that the product of this gene is secreted and consequently not involved in classical class I antigen-presentation. The truncated and conserved character of Amcr-UA lead us to define it as a nonclassical gene that is related to the few available squamate class I sequences. However, phylogenetic analysis placed Amcr-UA in a basal position relative to other published classical MHC genes from squamates, suggesting that this gene diverged near the beginning of squamate diversification.
Faculties and Departments:05 Faculty of Science > Departement Umweltwissenschaften > Zoologie > Evolution des Immunsystems (Du Pasquier)
UniBasel Contributors:Du Pasquier, Louis
Item Type:Article, refereed
Article Subtype:Research Article
Bibsysno:Link to catalogue
Publisher:Public Library of Science
e-ISSN:1932-6203
Note:Publication type according to Uni Basel Research Database: Journal article
Last Modified:31 Aug 2018 06:40
Deposited On:22 Mar 2012 13:38

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