Studies On The Genetic Variations Of ND5 And GHSR Gene And Its Association With Growth Traits In Six Cattle

PCR-SSCP and DNA sequencing techniques was used to detect the genetic diversity of the mtDNA ND5 gene and GHSR gene in Nanyang catlle, Qinchuan cattle, Jiaxian Red cattle, Luxi, Angus, and Chinese Holstein and association analysis were carried out to evaluate the effects of genotypes of candidate genes on growth traits of Nanyang catlle, Qinchuan cattle, and Jiaxian Red cattle. The results showed that:1.The genetic polymorphisms of the mtDNA ND5 gene in six cattle breedsPCR-SSCP and DNA sequencing techniques was used to detect the genetic diversity of the mtDNA ND5 gene. There were only one bandpattern in N1 locus and N3 locus after detected by PCR-SSCP technique. At the N2 locus, two kinds of haplotypes, named A and B, with three SNPs (12900 T >C,12923 A>T,12924 C>T,ref. NC₀06853) were detected. The 12900 T >C SNP is a silent mutation, and 12923 A>T and 12924 C>T SNPs cause Phe to be changed to Tyr. The frequencies of haplotype A in six breeds were 0.167,0.134,0.139,0.117,0.041,0.066, respectively.2.The association between the ND5 gene polymorphisms and the growth traits in three cattle breedsThe correlation analysis between the polymorphism of mtDNA ND5 gene and the body height, body length, body weight, hucklebone width, average day gain and circumference of cannon bone of Nanyang cattle revealed that: at 6 months, haplotype B had greater hucklebone width (P<0.01), body height, body length, body weight, and average daily gain (P<0.05) than haplotype A. At 24 months, haplotype A had greater body height than haplotype B (P<0.01). And at 12, 18 months, there was no significant differences between them (P>0.05).The correlation analysis between the polymorphism of mtDNA ND5 gene and the growth traits of Qinchuan and Jiaxian cattle revealed that: in Qinchuan cattle, there were no significant differences between them (P>0.05); In Jiaxian cattle population, haplotype A had greater hucklebone width than haplotype B (P<0.01). 3.The genetic polymorphisms of the GHSR gene in six cattle breedsPCR-SSCP and DNA sequencing techniques was used to detect the genetic diversity of the GHSR gene whole exon with G1, G2, G3 and G.4 loci. And nt-7, nt456, nt 667, nt3552 were detected. (ref. XM₅92014, the start translation site is"+1".)There were three band patterns in G1 locus, the mutation (C>A) was detected at nt-7 location. The frequencies of Allele C in six breeds were 0.729,0.557,0.543,0.536,0.539,0.852, respectively. There were two SNPs nt456 and nt667 with G>A, C>T were detected in this locus and two bands were found in this locus, named AA and AB. The SNPs at nt456 and nt667 were always in linkage with GC and AT together, respectively; BB genotype was not detected in six cattle breeds. The frequencies of Allele A in six breeds were 0.889,0.855,0.891,0.903,0.762,0.910, respectively. There did not found any mutation in G3 locus. Two bands were detected in G4 locus, the mutation (C>T) was detected at nt3552 location. The frequencies of Allele C in six breeds were 0.556,0.549,0.577,0.540,0.560,0.508, respectively. In this study, G1 locus was in Hardy-Weinberg disequilibrium (P<0.05). The PIC of detected SNPs in 6 population was moderate polymorphic (0.250.05). The PIC of detected SNPs in 6 population was moderate polymorphic (0.25