| Mx I(Myxovirus resistance) is a novel antivirus protein that is induced by IFNα/β. Based on the polymorphisms of Mx I gene, the effects of Mx I gene on production traits and immune indice of Yellow IV broilers were investigated to provide evidence for the basic genetic research and breed improvement.Single nucleotide polymorphisms of Exon3, Exon4, Intron4, Exon5, Exon7, Exon13 and Exonl4 of Mx I gene was detected by PCR-SSCP and sequencing in Yellow IV broilers. The results showed that six mutation loci, named Exon3, Intron4, Exon5, Exon7, Exon13 and Exonl4 were found. There were six genotypes, named AA, AB, BB, AC, BC and CC were found in Intron 4 and three genotypes, AA, AB and BB, were found in the other loci.Sequencing results indicated that three mutations (T→C, A→T, G→A) exist in Intron4. There were three mutations (C→A,T→C,T→G) in Exonl4 and the three mutations were not the nucleotide site that could enhance the disease resistance in previous research. Four mutation sites were detected in Exon3, Exon5, Exon7, Exon13.Association analyses of the body weights and body measurements of Yellow IV broilers showed that, in male popultation, those of the genotype CC of Intron4 was significantly higher than the others'. In female population, genotype BB of Exon5 was not found and there was significantly difference in chest depth and very significantly difference in shank girth between AA and AB; In Exon7, the 6th week body weight of genotype BB was significantly higher than that of AB; the genotypes of the Exonl4 have significantly effect on the 4th - 8th weeks body weight in female population; the body weight of genotype BB was significantly lower than that of AB; the body weight of genotype BB was also significantly lower than that of AA in the body weight of 6th and 8th. This suggested that the genotype BB of Exon14 was the advantageous genotype in late growth rate.Analyses of slaughter traits showed that, in female population, the breast muscle percentage of genotype BB of Exon3 was significantly lower than that of AB. The eviscerated carcass ratio of genotype AA of Exon7 was significantly lower than that of AB and BB. Combining with the body weight traits, we could found that traits of the genotype BB was superior to that of the genotype AA and AB. In male population, the genotype BB of Exon 13 gave the lowest the breast muscle percentage and was significantly different from that of the genotype AB and AA, Put together all the date of slaughter traits, it tended that genotype AA> genotype AB> genotype BB. In Exon14, the eviscerated carcass ratio of genotype AA was significantly lower than that of BB, and the abdomen fat percentage of genotype AA was significantly higher in male population. Contrarily, the body weight of genotype BB was higher than that of AA in female population. So when we carried on breeding, we should pay attention to the effect of sex. The result of slaughter traits was different from that of the body weight and the body measurement in Intron4. As a whole population, there was a tendency of slaughter traits that AA> AB> BB in Exon5.In immunal indice, the bursal weight of genotype AA of Exon7 was higher than that of BB significantly in male population, and in female population, the leukocyte count of genotype AA of Exon13 was also higher than that of BB significantly in female population. In the Exon14, the thymus weight of genotype BB was lower than that of AB and AA significantly in female population, contrary to that in male population. Combining with the relation between various genotype and growth traits of Exon14, we could find that this mutation locus is of great importance for growth traits and immune performance in male population. |
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