Study On The Relationship Between SNPs In Duck Pax3 Promoter, The Expression Of Related Genes And Meat Production

Satellite cells represent the oldest known adult stem cells which are involved in normal growth of muscle, they play a major role in muscle hypertrophy. Pax3 and Pax7 are the marker genes of satellite cells. The present study shows that Pax3 is one of the important genes to control growth and development of vertebrate limbs in embryonic period, while Pax7 is more contact with the repair of muscle damage. To be sure, these two genes have some relationship with muscle growth and development. There is a large difference in meat production ability among Nonghua duck, Jianchang duck and Heiwu duck. In order to discuss the relationship between Pax3 and related genes with these duck breed's meat production ability, this study found the potential SNP sites which were located in Pax3 promoter region, then analysis whether there are SNP sites in Pax3 promoter region which can effect the meat production ability. Furthermore, we chose Pax3?Pax7?MyoD?MyoG as candidate genes, then detected the expression of Pax3?Pax7?MyoD?MyoG at mRNA level and the expression of Pax3 and Pax7 at protein level at two weeks of age. The results were as follows:1. We obtained 1271bp on 5' flanking region sequence of the Pax3 gene by RT-PCR, amplification and sequencing analysis. The bioinformatic assay showed that typical CAAT-Box?TATA-Box?G-Box?GATA-Box domains were found in the duck Pax3 promoter region. There were also GATA-1?Sp-1 and MyoD transcription factor binding sites in this region. Besides, no CpG island was found.2. The genetic variation detected in NongHua, Jianchang and Heiwu duck showed that 26 possible SNP sites were found in the Pax3 promoter region. But there are only 5 SNP sites which conform to the Hardy-Weinberg Law:SNP1?SNP16?SNP19?SNP21?SNP24. The associations of the polymorphism with carcass traits were studied among different genotypes showed that:In SNP1 and SNP 16, the belly fat weight, sebum weight, leg fat weight in Nonghua and Heiwu ducks' BB genotype are higher than AB genotype; In SNP 19, the belly fat weight, sebum weight, leg fat weight, leg muscle weight and breast muscle weight in Heiwu ducks' BB genotypes are higher than AB genotypes; In SNP21, the belly fat weight, sebum weight, leg fat weight in Jianchang and Heiwu ducks'AB genotypes are higher than BB genotypes; In SNP 24, the belly fat weight, sebum weight, leg fat weight in Jianchang ducks' AB genotypes are higher than BB genotypes. The differences are not significant (P>0.05).3. Pax7 and Pax3 at mRNA level are highly expressed in Nonghua duck(P<0.05); Then the expression of Myod at mRNA level among these three duck breeds has no significant difference, but the mRNA expression of MyoD has a decreasing trend in Heiwu duck, Jianchang duck and Nonghua duck in turn(P>0.05); The mRNA level expression of MyoG in Jianchang duck is much higher than other two duck breeds (P<0.05). The mRNA level expression of MyoG has no linear relationship with muscle content among different duck breeds. So there may be no significant correlation between the expression of MyoG and muscle deposition.4. In protein level, the expression of Pax3 and Pax7 has the same trend, it is highest in Nonghua duck, in Jianchang duck the expression of Pax3 and Pax7 is higher than in Heiwu duck(P>0.05).5. The expression of Pax3 and Pax7 at both mRNA and protein level is high in Nonghua duck, it suggests that Pax3 and Pax7 genes are higher expressed in breed whose muscle content is highest. The increase in Pax3 and Pax7 mRNA and protein expression in Nonghua duck may provide a possible mechanism for the increase in muscle content compared to Jianchang duck and Heiwu duck.