Gene duplication and fragmentation in the zebra finch major histocompatibility complex

Christopher N Balakrishnan, Robert Ekblom, Martin Völker, Helena Westerdahl, Ricardo Godinez, Holly Kotkiewicz, David W Burt, Tina Graves, Darren K Griffin, Wesley C Warren, Scott V Edwards

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.