Cloning And Polymorphisms Of Macrophage Migration Inhibitory Factor Gene From Channel Catfish Ictalurus Punctatus

Channel catfish (Ictalurus punctatus) is an important aquacultural fish. It was introducedfrom the United States in1984. It was used as an important aquacultural species cultured inmore than20provinces in China. But due to the technology and pathogenic infection, theproduction of channel catfish was declined, and has caused serious economic losses to theaquaculture industry. The research on the immune gene of channel catfish may help useffectively control the occurrence of diseases. Many years of research indicate that MIF is akind of important factors of immune. MIF plays an important role in autoimmune disease, cellproliferation, and the formation of tumor blood vessels.Base on the EST of MIF gene of channel catfish, we obtain3′untranslated region (UTR)by using the RACE technology. We identify the promoter region of MIF gene by GenomeWalking technology. The two inrons of the MIF gene is also obtained by PCR. The length ofthe genomic sequence of MIF is3918bp. consisting of a348bp open reading frame (ORF), a70bp5′-untranslated region (UTR), a160bp3′-UTR, two introns as243and1441bp, anda1382bp promoter.In this experiment, we analyze the genomic sequence of MIF of channel catfish, and fourrepetitive sequences was found. MIF genomic sequence polymorphism analysis wasperformed in30individuals of channel catfish. The results showed that MIF genomicsequence include sixty sites of single nucleotide polymorphisms (SNPs). There are29siteslocating in the promoter,1is in5’ UTR,7are in3’ UTR,1is in exon and22are in introns.Among which,6sites were found in the binding sites for transcription factor. QuantitativeReal time PCR (qRT-PCR) was employed to measure MIF mRNA expression in six tissues ofchannel catfish. The results showed that intestine own the highest expression level of MIF, thelowest expression level of MIF is in muscles, the expression level of MIF of head kidney andliver is inferior to gills and spleen. The study provides more molecular biology information forthe rearch of MIF genomic sequence, and provides important clues to further study therelationship between gene promoter polymorphism and diseases.