Cloning and tissue expression profiling of the GnRHR gene of the Muscovy duck (Cairina moschata): polymorphism and association with egg-laying performance

1. cDNA sequence of gonadotropin-releasing-hormone receptor (GnRHR) gene was cloned and an association analysis between mutations and laying performance was conducted.2. A 1680-bp cDNA sequence of Muscovy duck GnRHR, which encodes 415 amino acids, was obtained and characterised. Phylogenetic analysis revealed that Muscovy duck GnRHR has a close relationship with Gallus gallus GnRHR.3. There were significantly different expression profiles between 4 age periods in the hypothalamus, pituitary, and ovary. The expression of GnRHR at the age of 36 weeks (laying period) was higher than other time points in the three tissues. GnRHR was expressed in 12 different tissues. The highest expression levels were observed in hypothalamus, pituitary and gonads.4. A single nucleotide polymorphism detected in the second intron was associated with egg-laying performance. Individuals with genotype TT had better egg-laying performance from individuals with genotypes CC or TC. Therefore, GnRHR could be used as a marker gene for laying performance in Muscovy duck.

1. 本研究克隆了促性腺激素释放激素受体（gonadotropin-releasing-hormone receptor, GnRHR）基因的互补脱氧核糖核酸（complementary deoxyribonucleic acid, cDNA）序列，并开展了该基因突变与产蛋性能之间的关联分析。
2. 本研究获得并鉴定了番鸭（Muscovy duck）GnRHR基因的1680 bp互补脱氧核糖核酸序列，其编码415个氨基酸。系统发育分析（phylogenetic analysis）结果显示，番鸭GnRHR与原鸡（Gallus gallus）GnRHR的亲缘关系较近。
3. 番鸭下丘脑、垂体及卵巢组织中，GnRHR在4个不同日龄阶段的表达谱（expression profiles）存在显著差异。在36周龄（产蛋期）时，该基因在上述三种组织中的表达量均高于其余采样时间点。此外，GnRHR在12种不同组织中均有表达，以下丘脑、垂体与性腺中的表达水平最高。
4. 本研究在GnRHR基因第二内含子（intron）区域检测到的单核苷酸多态性（single nucleotide polymorphism）位点与番鸭产蛋性能显著相关。基因型为TT的个体，其产蛋性能优于基因型为CC或TC的个体。因此，GnRHR可作为番鸭产蛋性能相关的分子标记基因。