Molecular cloning and comparative analysis of immunoglobulin heavy chain genes from Phasianus colchicus, Meleagris gallopavo, and Coturnix japonica.
To date, immunoglobulin (Ig) genes have only been fully characterized in a small number of aves, which pose a major obstacle to understanding Ig evolution. Thus, we cloned the cDNAs of three immunoglobulin classes, IgA, IgM, and IgY, from Phasianus colchicus, Coturnix japonica, and Meleagris gallopavo. Multiple sequence alignments revealed that the highest degree of sequence homology in all Ig classes was observed between pheasant and turkey whereas the degree of homology between the galliforms and non-galliforms was relatively low compared to that among the galliforms. When the constant region domains of the four human Ig classes were compared with the corresponding regions in aves, the average percent homology between human CH2 and avian CH3, and between human CH3 and avian CH4, was greater than between identical domains in IgA and IgY, which are in partial agreement with the hypothesis that the avian CH2 domain evolved to form the mammalian hinge via domain condensation. Phylogenetic analysis showed that the galliform Ig heavy chain constant regions were divided into quail and the common ancestor of chicken, turkey, and pheasant, and that chicken was separated from turkey and pheasant, which were grouped together. These results add to our knowledge of galliform Igs and the diversification of these genes.
Choi
Jin Won
JW
WCU Biomodulation Major, Department of Agricultural Biotechnology, and Research Institute for Agriculture and Life Sciences, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151-921, Republic of Korea.
Kim
Jin-Kyoo
JK
Seo
Hee Won
HW
Cho
Byung Wook
BW
Song
Gwonhwa
G
Han
Jae Yong
JY
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001717:Birds / Q000235:genetics / Q000276:immunology*; D003001:Cloning, Molecular; D019143:Evolution, Molecular; D007143:Immunoglobulin Heavy Chains / Q000235:genetics / Q000276:immunology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D012313:RNA / Q000737:chemistry / Q000235:genetics; D019105:Random Amplified Polymorphic DNA Technique / Q000662:veterinary; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
D007143:Immunoglobulin Heavy Chains; D012313:RNA