Abstract: The study was designed to analyze the genetic polymorphism and variability of NGB gene exon 4 of Simmental cattle hybrid taxon in Gansu Linze, Ganzhou, Liangzhou, Jinchang, and Gaotai five regions.DNA fragment containing the exon 4 and part of intron of NGB gene were amplified and genotyped using PCR single-strand conformational polymorphism (SSCP) method.Representative alleles were sequenced for verification of their variations in DNA sequences.The results displayed that there were 5 alleles (A, B, C, D and E) detected, combined six genotypes as AA, BB, AB, AC, AD and AE.Among them, AA, BB and AB genotypes were all detected in the five regions.AC, AD and AE genotypes was detected in Ganzhou, Liangzhou and Gaotai respectively.Allele A was the predominant genotype in five regions.Sequence of the SSCP showed 5 mutations in the DNA fragment (31 bp C→T, 68 bp G→C and G→A, 129 bp A→G, 207 bp C→T).In which, C→T at 207 bp was located in exon, while the other mutations were located in intron.But all had not leaded to amino acid changed.Chi-square testing indicated that in the 207 bp single nucleotide mutation sites, only Liangzhou, Jinchang Simmental cattle hybrid taxon among the five regions were in Hardy-Weinberg equilibrium (P>0.05).Population genetics analysis showed the polymorphism information content were 0.358 2, 0.383 9, 0.427 9, 0.368 2 and 0.394 7 in Linze, Ganzhou, Liangzhou, Jinchang, Gaotai, respectively, which were all at a moderate level of polymorphism (0.25

Key words: Simmental cattle hybrid taxon, NGB gene, Exon, Genetic variation

CLC Number: 

• Q78