| PCR-SSCP and PCR-RFLP was applied to analyze the polymorphism of Leptin gene in 542 cattle that comprised of six bovine breeds, namely Nanyang cattle, Qinchuan cattle, Jiaxian Red cattle, Xizhen cattle, Luxi cattle and Chinese Holstein cow. The genetic variations of 5 genes including Leptin, DRB3, GDF-8, Pit-1 and Calpastatin in six breeds were researched. The performance traits including body weight and body measurements were measured. The association between genetic polymorphisms and performance traits were analyzed by using general linear model (GLM). The results were as follows:1. Relativity of polymorphism of the Leptin gene with growth and development traits.A 330 bp -long PCR product was amplified and sequenced. Moreover, the frequencies of alleles A/B of Nanyang cattle, Qinchuan cattle, Jiaxian Red cattle, Xizhen cattle, Luxi cattle and Chinese Holstein cow were 0.558/0.442, 0.492/0.508, 0.571/0.429, 0.658/0.342, 0.591/0.409, 0.615/0.385 respectively. Gene heterozygosity/ effective allele gene number /polymorphism information content of Nanyang cattle, Qinchuan cattle, Jiaxian Red cattle, Xizhen cattle, Luxi cattle and Chinese Holstein cow were 0.493/1.973/0.371, 0.499/1.999/0.374, 0.489/1.96/0.369, 0.450/1.818/0.348, 0.483/1.936/0.366, 0.473/1.899/0.361 respectively. According to the genetic diversity indexes described above of the six cattle breeds, Qinchuan cattle and Nanyang cattle had the most abundant genetic diversity and showed high polymorphism, and Jiaxian Red catte, Luxi cattle, Chinese Holstein cow were inferior, while Xizhen cattle had the lowest genetic variability. Association of variations of Leptin gene with growth traits among 3 populations was analyzed. In height at hip cross, individuals with genotype BB were higher than that with genotypes AA and AB in Qinchuan population, that is, BB>AA,AB(P<0.05). So Leptin gene can be one of the candidate genes for growth traits with height at hip cross, not for body weight, heart length and body length trait. In body length, heart length, body weight, hucklebone width, body height, and average day gain, individuals with genotype BB in Nanyang population were higher than that with genotypes AA and AB in Nanyang population except body height, average day gain in 12 months and hucklebone width, average day gain in 18 months. And the polymorphisms of the Leptin gene were caused by G→T transition at 66 bp position, A→C transition at 67 bp position and G→T transition at 299 bp position. These results may be applied to marker assisted selection. 2. Relativity of polymorphism of the DRB3 gene with growth and development traits.The frequencies of alleles A/B of Nanyang cattle, Qinchuan cattle, Jiaxian Red cattle, Xizhen cattle, Luxi cattle and Chinese Holstein cow populations were 0.453/0.547, 0.454/0.546, 0.458/0.542, 0.579/0.421, 0.545/0.455, 0.566/0.434 respectively. For Nanyang cattle , Qinchuan cattle, Jiaxian Red cattle, Xizhen cattle, Luxi cattle and Chinese Holstein cow, gene heterozygosity/ effective allele gene number/ polymorphism information content were 0.496/1.982/0.373, 0.496/1.983/0.373, 0.496/1.986/0.373, 0.488/1.951/0.369, 0.496/1.984/0.373, 0.491/1.966/0.371 respectively. And the polymorphisms of the DRB3 gene were caused by C→T transition at 36 bp position, A→T transition at 88 bp position and C→T transition at 198 bp position.3. Relativity of polymorphisms of the GDF-8 gene with growth and development traits.The frequencies of alleles A/B of Nanyang cattle, Qinchuan cattle, Jiaxian Red cattle, Xizhen cattle, Luxi cattle and Chinese Holstein cow populations were 0.425/0.575, 0.431/0.569, 0.58/0.42, 0.632/0.368, 0.432/0.568, 0.533/0.467 respectively. For Nanyang cattle, Qinchuan cattle, Jiaxianhong cattle, Xizhen cattle, Luxi cattle and Chinese Holstein cow, gene heterozygosity/ effective allele gene number/ polymorphism information content were 0.489/1.955/0.369, 0.49/1.962/0.37, 0.487/1.95/0.368, 0.465/1.87/0.357, 0.491/1.963/0.37, 0.498/1.991/0.374 respectively. And the polymorphisms of the GDF-8 gene were caused by C→G transition at 196 bp position, A→T transition at 88 bp position and C→A transition at 331 bp position.4. Relativity of polymorphisms of the PIT4 gene with growth and development traits.The frequencies of alleles A/B of Nanyang cattle, Qinchuan cattle, Jiaxian Red cattle, Xizhen cattle, Luxi cattle and Chinese Holstein cow populations were 0.565/0.435, 0.638/0.362, 0.542/0.458, 0.526/0.474, 0.545/0.455, 0.566/0.434 respectively. For Nanyang cattle, Qinchuan cattle, Jiaxian Red cattle, Xizhen cattle, Luxi cattle and Chinese Holstein cow gene heterozygosity/ effective allele gene number /polymorphism information content were 0.492/1.967/0.371, 0.462/1.858/0.355, 0.496/1.986/0.373, 0.499/1.994/0.374, 0.496/1.984/0.373, 0.491/1.966/0.371 respectively.5. Relativity of polymorphisms of the PIT5 gene with growth and development traits.The frequencies of alleles A/B of Nanyang cattle, Qinchuan cattle, Jiaxian Red cattle, Xizhen cattle, Luxi cattle and Chinese Holstein cow populations were 0.444/0.556, 0.477/0.523, 0.538/0.462, 0.421/0.579, 0.523/0.477, 0.475/0.525 respectively. For Nanyang cattle, Qinchuan cattle, Jiaxian Red cattle, Xizhen cattle, Luxi cattle and Chinese Holstein cow, gene heterozygosity/ effective allele gene number/ polymorphism information content were 0.494/1.975/0.372, 0.499/1.996/0.374, 0.497/1.988/0.374, 0.488/1.951/0.369, 0.499/1.996/0.374, 0.499/1. 995/0.374 respectively.6. Relativity of polymorphisms of the CAST gene with growth and development traits.The frequencies of alleles A/B of Nanyang cattle, Qinchuan cattle, Jiaxian Red cattle, Xizhen cattle, Luxi cattle and Chinese Holstein cow populations were 0.524/0.476, 0.469/0.531, 0.507/0.493, 0.447/0.553, 0.409/0.591, 0.352/0.648 respectively. For Nanyang cattle, Qinchuan cattle, Jiaxian Red cattle, Xizhen cattle, Luxi cattle and Chinese Holstein cow gene heterozygosity/ effective allele gene number/ polymorphism information content were 0.499/1.996/0.374, 0.498/1.992/0.374, 0.5/2/0.375, 0.494/1.978/0.372, 0.483/1.936/0.367, 0.456/1.84/0.352 respectively. And the polymorphisms in the GDF-8 gene were caused by C→G transition at 962 bp position.7. Genetic loci analysis from Hardy-WeinbergAll the six genetic loci of Nanyang cattle and Leptin,CAST loci of Qinchuan and DRB3,GDF-8,PIT4,CAST loci of Jiaxian Red and Leptin,DRB3,GDF-8,PIT5 loci of Chinese Holstein were significantly deviated from the Hardy-Weinberg equilibrium(P<0.01). While all the six genetic loci of Xizhen cattle and Luxi cattle and DRB3,GDF-8,PIT4,PIT5 loci of Qinchuan cattle and PIT4,CAST loci of Chinese Holstein were at Hardy-Weinberg equilibrium (P>0.05).8.χ2 genotypes value of the six genetic loci of the six different cattle populationsTheχ2 value of genotypes indicated that it was deemed significant between Jianxian Red with Nanyang, Qinchuan and Chinese Holstein at Leptin locus(P<0.01)and between Chinese Holstein with Nanyang at DRB3 locus(P<0.01), and between Chinese Holstein with Qinchuan at DRB3 locus(P<0.05), and between Nanyang with Qinchuan and Jiaxian Red cattle at GDF-8 locus(P<0.01), and between Qinchuan with Jiaxian Red, Xizhen and Chinese Holstein cattle at GDF-8 locus(P<0.05), and between Jiaxian Red with Qinchuan cattle at PIT-4 locus(P<0.01), and between Nanyang with Jiaxian Red cattle at PIT-5 locus(P<0.01), and between Chinese Holstein with Jiaxian Red, Nanyang and Qinchuan cattle at PIT-5 locus(P<0.01), and between Chinese Holstein with Luxi cattle at PIT-5 locus(P<0.05), and between Chinese Holstein with Jiaxian Red, Nanyang and Qinchuan cattle at CAST locus(P<0.01), between Chinese Holstein with Xizhen and Luxi cattle at CAST locus(P<0.05). |
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