关键词: 尼罗罗非鱼；MHC IA；基因克隆；多态性；RACE

Abstract:

In this study, The PCR products by rapid amplification of cDNA ends polymerase chain reaction(RACE PCR) and touchdown PCR from the tilapia MHC class IA gene 3’ end were spliced and sequenced. The two 957bp cDNA sequences were newly obtained and named orni DAA*0101 and orni DAA*0102, respectively. They encode two newly discovered subtypes of the alleles from tilapia MHC class IA gene. Both of the two cDNA fragments contain a 666bp CDS region which consists of: a partial peptidebinding region, an immunoglobulin like region, a transmembrane region, a cytoplasmic region and with a 291bp 3’ UTR region. Homologous comparison shows that the cDNA sequences have two transition sites in 388bp and 426bp, but the amino acid sequences have only one single amino acid changed in the 130th site: the differences between Glutamic and Lysine. It is the first time to discover an amino acid variation in the relatively conservative IGC domain. The information newly obtained has an important value to reveal the relationship between high disease 20130419resistance and polymorphism of tilapia MHC class IA gene.

Key words: Oreochromis niloticus; MHC IA gene; cloning; polymorphism; RACE