title: Evolution of the proto-MHC ancestral region: more evidence for the plesiomorphic organisation of human chromosome 9q34 region.
abstract: The present day structure of the vertebrate major histocompatibility complex (MHC) and its three paralogous regions has always been a focus of interest. In a recent study, nine human anchor genes located in the MHC region were cloned from a Branchiostoma floridae (amphioxus) cosmid library. The identification and analysis of 31 surrounding genes led to the most probable model of two rounds of en bloc duplication giving rise to these regions. These events were estimated to have occurred after the cephalochordata-craniata divergence [approximately 766 million years ago (Mya)] and before the Gnathostomata radiation (approximately 528 Mya). Furthermore, it was also shown that after this large-scale duplication one of these regions, corresponding to the human 9q33-q34, had retained an ancestral organisation. In the present study, four new cosmids in the amphioxus proto-MHC region were identified by the chromosomal walking technique. These cosmids were sequenced, and their structural annotation was performed, leading to the prediction of eleven genes. Their phylogenetic relationships among species corroborate the results obtained previously and provide more evidence for the plesiomorphic state of the human chromosome 9q33-34 MHC paralogous region.
authors.affiliation: EA Biodiversité 2202, Université de Provence, Place V. Hugo, 13331 Marseille cedex 3, France. avienne@up.univ-mrs.fr
authors.forename: Alexandre
authors.initials: A
authors.lastname: Vienne
authors.forename: Takashi
authors.initials: T
authors.lastname: Shiina
authors.forename: Laurent
authors.initials: L
authors.lastname: Abi-Rached
authors.forename: Etienne
authors.initials: E
authors.lastname: Danchin
authors.forename: Verane
authors.initials: V
authors.lastname: Vitiello
authors.forename: François
authors.initials: F
authors.lastname: Cartault
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Inoko
authors.forename: Pierre
authors.initials: P
authors.lastname: Pontarotti
mesh_terms: D000818:Animals; D002899:Chromosomes, Human, Pair 9; D019143:Evolution, Molecular; D006801:Humans; D008285:Major Histocompatibility Complex / Q000235:genetics*; D010802:Phylogeny; D017422:Sequence Analysis, DNA