| Growth axis-related genes are involved in the regulation of growth correlating with certain characteristics such as the maturation of the muscles and bones, fat deposit and feed conversion, the hypothalamus, according to the need of growth, controls the pituitary through secreting the growth hormone releasing hormone and somatostatin, subsequently, the pituitary controls the secretion of the growth hormone(GH). Having circulated into liver through blood, GH binds its receptor on the surface of cell membrane, and it activates the mechanism of cellular transfer signal to induce the secretion of insulin-like growth factors (IGFs) which then circulate into target tissues through blood to accelerate the growth and differentiation of cells within the tissues. This experiment was conducted to study GH GHR and IGF-1 genes and set up several PCR-RFLP systems which included three site:Msp I of intron 1 of GH gene, Pst I of the 5' region of the IGF-1 gene and Hindill of intron 2 of the GHR gene. The genetic variability of the three sites were detected in eight chicken breeds (two foreign breeds and six native breeds), and the influence on the chicken performance was studied in Ningdu Yellow Fowl, Wanzai Kangle Fowl and Taihe Silky Fowl.Many researches have indicated the genetic mechanism of dwarf chickens was closely associated with the mutation of GHR gene. The different dwarf phenotypes of sex-linked dwarf chicken population resulted from different kinds of mutation of GHR such as the mutation of structure and encode region, the mutation of site where could be digested by enzyme, DNA fragment deleted, and even the mutation which produce in the regulation region. There were different effect on the dwarf phenotype among different alleles. The mutation of the GHR gene affected at least the chickens' performance even though it did not make them become dwarf. By DHPLC and direct sequence, several new SNPs were found, one of them was applied to detect the genetic variation in 24 native poultry breeds, and another one was applied to detect the genotype of Wenshi full-sib reference population and study its effect on the performance.Till now, only one GHR intron (intron5) sequence was known. To make the whole structure of GHR clearer, cloning and sequencing were used to obtain the sequence of intron 8 and intron 9.The results of the experiment were as follows:1. The relationships between cGH, cIGF-1 genotype and some performance were studied in randomized population, furthermore, the effect of a new SNP on the performance was also studied, the result indicated that the same site had different effects on chicken's performance in different breeds,mating types and sexes.2. We searched for new SNPs ranged in exon 10 and 3' UTR region which totally covered 2500bp sequence.9 SNPs were found in 3' UTR, 4 mutation of them arose at the the site of restriction enzyme .6 SNPs were found in exon 10, 3 mutation of them arose at the sites ofrestriction enzyme. And the mutation of 3 SNPs changed amino acid, that was ,the mutation of amino acid at position 203 (Ser Thr) in exon 10 resulted from mutation at position 1507(G/T) in cGHRmRNA and 3' UTR sequence; at position205 (Thr Ser) resulted from mutation at position 1512(A/T);at position 234 (Glu Gln) resulted from mutation at position 1598(G/C).3. Nucleotide mutation at the position 2907(C/A) in cGHRmRNA and 3' UTR made the restriction enzyme BSURl (GGCC) can not digest it. We named GGAC gene A, and the other one was gene B. The results showed there was different genotype frequency between dwarfish and normal chickens. The genotype frequency of AA, AB and BB genotype was 0.93, 0.07 and 0 respectively in dwarfish chickens. But in normal chickens genotype BB was dominant and only 0-3 AA genotype existed. Therefore, it could be considered as a new related mutation which induced dwarfish.4. By cloning and sequencing, the whole sequences of intron 8 and 9 of cGHR gene in Lai Hang Fowl were obtained, which had been logged into the GenBank, the ID of intron 8 and intron 9 was A...
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