title: A Comprehensive Analysis of the Phylogeny, Genomic Organization and Expression of Immunoglobulin Light Chain Genes in Alligator sinensis, an Endangered Reptile Species.
abstract: Crocodilians are evolutionarily distinct reptiles that are distantly related to lizards and are thought to be the closest relatives of birds. Compared with birds and mammals, few studies have investigated the Ig light chain of crocodilians. Here, employing an Alligator sinensis genomic bacterial artificial chromosome (BAC) library and available genome data, we characterized the genomic organization of the Alligator sinensis IgL gene loci. The Alligator sinensis has two IgL isotypes, λ and κ, the same as Anolis carolinensis. The Igλ locus contains 6 Cλ genes, each preceded by a Jλ gene, and 86 potentially functional Vλ genes upstream of (Jλ-Cλ)n. The Igκ locus contains a single Cκ gene, 6 Jκs and 62 functional Vκs. All VL genes are classified into a total of 31 families: 19 Vλ families and 12 Vκ families. Based on an analysis of the chromosomal location of the light chain genes among mammals, birds, lizards and frogs, the data further confirm that there are two IgL isotypes in the Alligator sinensis: Igλ and Igκ. By analyzing the cloned Igλ/κ cDNA, we identified a biased usage pattern of V families in the expressed Vλ and Vκ. An analysis of the junctions of the recombined VJ revealed the presence of N and P nucleotides in both expressed λ and κ sequences. Phylogenetic analysis of the V genes revealed V families shared by mammals, birds, reptiles and Xenopus, suggesting that these conserved V families are orthologous and have been retained during the evolution of IgL. Our data suggest that the Alligator sinensis IgL gene repertoire is highly diverse and complex and provide insight into immunoglobulin gene evolution in vertebrates.
authors.affiliation: State Key Laboratory of Agrobiotechnology, College of Biological Sciences, National Engineering Laboratory for Animal Breeding, China Agricultural University, Beijing, People's Republic of China.
authors.forename: Xifeng
authors.initials: X
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Agrobiotechnology, College of Biological Sciences, National Engineering Laboratory for Animal Breeding, China Agricultural University, Beijing, People's Republic of China.
authors.forename: Gang
authors.initials: G
authors.lastname: Cheng
authors.affiliation: Beijing Zoo, Beijing 100044, People's Republic of China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Beijing Zoo, Beijing 100044, People's Republic of China.
authors.forename: Chenglin
authors.initials: C
authors.lastname: Zhang
authors.affiliation: College of Life Sciences, Anhui Normal University, Anhui Provincial Key Laboratory of the Conservation and Exploitation of Biological Resources, Wuhu 241000, People's Republic of China.
authors.forename: Xiaobing
authors.initials: X
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Agrobiotechnology, College of Biological Sciences, National Engineering Laboratory for Animal Breeding, China Agricultural University, Beijing, People's Republic of China.
authors.forename: Haitang
authors.initials: H
authors.lastname: Han
authors.affiliation: State Key Laboratory of Agrobiotechnology, College of Biological Sciences, National Engineering Laboratory for Animal Breeding, China Agricultural University, Beijing, People's Republic of China.
authors.forename: Yaofeng
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Agrobiotechnology, College of Biological Sciences, National Engineering Laboratory for Animal Breeding, China Agricultural University, Beijing, People's Republic of China.
authors.forename: Liming
authors.initials: L
authors.lastname: Ren
mesh_terms: D000489:Alligators and Crocodiles / Q000235:genetics*; D000818:Animals; D056727:Endangered Species; D050439:Genes, Immunoglobulin Light Chain / Q000235:genetics*; D016678:Genome / Q000235:genetics; D010802:Phylogeny