Polymorphisms of intron 1, 3 and 4 of insulin-like growth factor I gene in largemouth bass.

The sequences of intron 1,3 and 4 of the largemouth bass IGF-I gene were isolated using primers that designed from IGF-I gene cDNA.PCR products of three introns were sequenced for detecting polymorphisms.The methods were developed for detecting polymorphisms.Moreover,the alleles frequencies of four polymorphisms were calculated in Chinese cultured population and American wild population.The results indicated: 1) The lengths of intron1,3 and 4 were 1 317bp,712bp and 1 941bp,respectively.2) Seven polymorphisms that included six SNPs and one insertion/deletion mutation were found in Chinese cultured population and American wild population.The polymorphisms in intron 1 were SNP G208A and SNP G1070A(number meant relative position in each intron);The polymorphisms in intron 3 were "A" nucleotide insertion/deletion mutation at 40 basepair and SNP G208A and SNPG1070A;The polymorphisms in intron 4 contained 20bp insertion/deletion mutation and SNP G1070A.The result indicated that there were abundant polymorphisms in largemouth bass IGF-I gene.3) The polymorphisms in introns 1 and 4 were genotyped by RFLP,CRS-RFLP and SSCP methods.4) In Chinese cultured population,only SNP G1070A in intron 1 was identified.The frequencies of genotypes were not significantly different between two populations.Other three polymorphisms did not exist in Chinese cultured population,which suggested that genetic diversity was very low in Chinese cultured population.