Studies On Genetic Diversity Of Growth Hormone Gene In Eight Breeds Of Duck

Growth hormone is one of the foremost hormone in regulating growth after animals are born, it could remarkable expedite the growth of muscles and bones, reduce the content of the fattiness, and accelerate the growth and development of animals, and so on. Growth hormone gene was used for the object of this research. The single nucleotide polymorphism (SNP) of growth hormone gene was investigated in various breeds of duck, including Beijing ducks, Xihu mallards, Cherry Valley Meat ducks, Jinding ducks, Shan Partridge ducks, Jingjiang ducks, Shaoxing ducks and Jinyun Partridge ducks. Twelve pairs of primers for coding and regulation regions, and intron 2,3 of GH gene were designed based on the database of duck genomic sequence(GenBank:AB158760)and the SNPs were detected by PCR-SSCP method. The objective of this research was to analyse the polymorphisms of GH, compared the frequency of genotypes, and probed into the relation of genotypes and breed traits of ducks, then provided the theory foundation for Marker-Assisted Selection in breeding for the future. The results are as the following:1. In 5′-UTR and 3′-UTR of growth hormone gene, two SNP were found among individuals: 230(C→G) and 244(C→A) in 5′-UTR. There was no SNP in 3′-UTR; it is that to say the 3′-UTR represented its own high conservativeness. The analytic results showed that: At loci of 5′-UTR, the sequence of 5′-UTR inclined to conservativeness of isozygoty in Beijing ducks, Xihu mallards, Cherry Valley Meat ducks, Shan Partridge ducks, and Jinyun Partridge ducks, and had a low variability in Shaoxing ducks and Jingjiang ducks, but had a high variability in Jinding ducks which reflected that Jinding ducks had own breed traits.2. In coding regions of growth hormone gene, only one SNP was found among individuals: 3701(C→T) in exon 4. However, the mutation at 3701 was a silence mutation. At loci of exon 4,the frequencies of genotypes in different breeds were significantly different, and the frequency of CC genotype in meat-type ducks were significantly higher than that in laying-type ducks,i.e., the C allele and D were the preponderant gene of meat-type ducks and laying-type ducks respectively. In addition, Beijing ducks and Cherry Valley Meat ducks with high C allele frequency were belong to meat-type ducks with high yield; Jinding ducks and Shaoxing ducks with high D allele frequency were belong to laying-type ducks with high yield.According to the results above, we can conclude that these SNPs may have relationship with some productive traits of ducks.3. In intron 2 and 3, eight SNP were found among individuals: 2593(C-T), 2770(G-A), 2813(T-A), 2829(C-A), 2894(C-T), 2896(T-C), 3100(C-G) in intron 2 and 3270(A-G) in intron 3. The analytic results showed that: All of the loci inclined to conservativeness of isozygoty in Shaoxing ducks, Beijing ducks and Cherry Valley Meat ducks (except the loci at 2593 in intron 2 for two of the latter), i.e., these breeds had their own conservativeness. But that of else breeds had abundant polymorphism, i. e., these breeds had their own variability. It is obvious that Beijing ducks, Cherry Valley Meat ducks and Shaoxing ducks had their own breed traits in variability of intron 2 and 3 of GH gene. Beijing ducks and Cherry Valley Meat ducks were belong to meat-type ducks with high yield; Shaoxing ducks was belong to laying-type ducks with high yield.According to the results above, we can conclude that these SNPs may have relationship with some productive traits of ducks.