Nie Q, Zeng H, Lei M, Ishag N A, Fang M, Sun B, Yang G, Zhang X
Department of Animal Genetics, Breeding and Reproduction, College of Animal Science, South China Agricultural University, Guangzhou, China.
Br Poult Sci. 2004 Oct;45(5):611-8. doi: 10.1080/00071660400006263.
(1) Ghrelin is a novel endogenous ligand for the growth hormone secretagogue receptor (GHS-R) and is expressed primarily in the stomach and hypothalamus with the probable function of stimulating GH secretion and food intake both in mammals and poultry. The complete sequences of ghrelin gene have been reported in humans and mice; however, that of chickens remains unclear. (2) Here, we report the complete sequence of chicken ghrelin gene (submitted to Genbank; accession number AY303688), which consists of 5 exons and 4 introns. As in mice, the first exon of chicken ghrelin gene does not encode any amino acid. (3) Scanning point mutations with denaturing high-performance liquid chromatography (DHPLC) using WAVE DNA Fragment Analysis Systems and confirmed with direct sequencing for polymerase chain reaction (PCR) products, we analysed the single nucleotide polymorphisms (SNPs) in the entire gene of chicken ghrelin. (4) Results showed that there were 19 SNPs in chicken ghrelin gene, and most of these SNPs were scattered in the 4 introns. In these SNPs, one mutation in exon 5 (A2355G) led to the change of amino acid from glutamine to arginine (Gln 113 Arg): as a result a different ghrelin precursor instead of a mature peptide was produced. In addition, one SNP in 5'UTR (C223G) determined the presence or absence of a potential binding site of transcription factor serum response factor (SRF), which might affect the expression of chicken ghrelin gene. Some of the SNPs detected in the present study could be used in quantitative trait loci (QTL) mapping for growth characters in chickens. (5) Because one SNP is located in a polymorphic site of restriction enzyme PagI of intron 4, it was possible to design a PCR-RFLP procedure and analyse the diversity of 10 chicken populations. Results showed the allelic frequencies of C2100T differ among these breeds, however, no significant difference was observed between imported breeds and Chinese native ones, nor between egg layers and meat type chickens. A chi-square test showed that 4 chicken populations of Beijing Fat, Xinghua, Recessive White and Silky followed the Hardy-Weinberg equilibrium.
(1) 胃饥饿素是生长激素促分泌素受体（GHS-R）的一种新型内源性配体，主要在胃和下丘脑表达，可能具有刺激哺乳动物和家禽生长激素分泌及食物摄入的功能。人类和小鼠的胃饥饿素基因完整序列已见报道；然而，鸡的胃饥饿素基因完整序列仍不清楚。(2) 在此，我们报道鸡胃饥饿素基因的完整序列（已提交至Genbank；登录号AY303688），该基因由5个外显子和4个内含子组成。与小鼠一样，鸡胃饥饿素基因的第一个外显子不编码任何氨基酸。(3) 使用WAVE DNA片段分析系统通过变性高效液相色谱（DHPLC）扫描点突变，并对聚合酶链反应（PCR）产物进行直接测序以确认，我们分析了鸡胃饥饿素整个基因中的单核苷酸多态性（SNP）。(4) 结果表明，鸡胃饥饿素基因中有19个SNP，其中大多数SNP分散在4个内含子中。在这些SNP中，外显子5中的一个突变（A2355G）导致氨基酸从谷氨酰胺变为精氨酸（Gln 113 Arg）：结果产生了一种不同的胃饥饿素前体而非成熟肽。此外，5'非翻译区的一个SNP（C223G）决定了转录因子血清反应因子（SRF）潜在结合位点的有无，这可能影响鸡胃饥饿素基因的表达。本研究中检测到的一些SNP可用于鸡生长性状的数量性状位点（QTL）定位。(5) 由于一个SNP位于内含子4的限制性内切酶PagI的多态性位点，因此有可能设计一种PCR-RFLP方法并分析10个鸡群体的多样性。结果表明，C2100T的等位基因频率在这些品种之间存在差异，然而，进口品种与中国本土品种之间以及蛋鸡和肉鸡之间均未观察到显著差异。卡方检验表明，北京油鸡、杏花鸡、隐性白鸡和丝羽乌骨鸡这4个鸡群体符合哈迪-温伯格平衡。
