Evolution of the Major Histocompatibility Complex Genes in Fish

The major histocompatibility complex (MHC) is a gene cluster directly related to immune response and because of its important immunological functions, the structure and evolution history of MHC is of great interest to world´s scientists. To elucidate the evolutionary history of MHC, the MHC class II antigen genes of 7 kinds of marine fish and 8 kinds of freshwater fish were selected. Then the phylogenetic relationships were explored by neighbour-joining and minimum-evolution methods. Based on two kinds of phylogenetic analysis, we knew that MHC evolutionary changes occurred in the early stage, but it´s followed by a period of evolutionary stability. The conclusion will provide guides for further research on MHC evolution history of other vertebrates.