Carcangiu V, Vacca G M, Mura M C, Dettori M L, Pazzola M, Luridiana S, Bini P P
Dipartimento di Biologia Animale, Università degli Studi di Sassari, Via Vienna 2, 07100 Sassari, Italy.
Anim Reprod Sci. 2009 Jan;110(1-2):71-8. doi: 10.1016/j.anireprosci.2007.12.014. Epub 2008 Jan 3.
The reproductive activity of goats bred in temperate latitude follows a seasonal pattern, influenced by annual variation in day length. Daily variation in pineal melatonin secretion is the neuroendocrine signal recognized by animals through the link between this hormone and melatonin receptor 1a (MTNR1A). A total of 345 goats of different breeds (225 Sarda, 30 Saanen, 30 Chamois Coloured, 30 Maltese and 30 Nubian) with a kidding period in October-December or January-March were analysed to verify if a link exists between the structure of the receptor gene and reproductive activity. The main part of exon II of MTNR1A gene was amplified by PCR and then digested with MnlI and RsaI to prove the presence of restriction sites. Sequencing of 20 cloned samples and 20 purified samples permitted comparison with previously published sequences. No polymorphism was found using MnlI enzyme, as all 345 samples showed the cleavage site in position 605 and all the goats were MM genotype. However, using RsaI enzyme, some Sarda goats, showed a polymorphic site in position 53. Nine Sarda goats were R/r genotype, lacking this cleavage site only in one allele, while the other animals, both Sarda and the other breeds, presented the cleavage site in both the alleles and were thus R/R genotype. No r/r genotype was found in any of the breeds. In Sarda goats the allelic frequency was 0.98 for R allele and 0.02 for r allele; genotypic frequency was 96.00% for R/R genotype and 4.00% for R/r genotype. A strong link emerged from statistical analysis (P<0.001) between R/r genotype and reproductive activity, which was strongly influenced by photoperiod. Sequencing indicated six nucleotide changes that did not induce any amino acid change. Data showed that polymorphism was present and that it influences reproductive activity only in the Sarda breed.
在温带地区饲养的山羊的繁殖活动呈现季节性模式，受日照长度的年度变化影响。松果体褪黑素分泌的每日变化是动物通过这种激素与褪黑素受体1a（MTNR1A）之间的联系所识别的神经内分泌信号。对总共345只不同品种的山羊（225只撒丁岛山羊、30只萨能山羊、30只羚羊色山羊、30只马耳他山羊和30只努比亚山羊）进行了分析，这些山羊的产羔期在10月至12月或1月至3月，以验证受体基因结构与繁殖活动之间是否存在联系。通过聚合酶链反应（PCR）扩增MTNR1A基因外显子II的主要部分，然后用MnlI和RsaI进行消化，以证明限制性位点的存在。对20个克隆样本和20个纯化样本进行测序，以便与先前发表的序列进行比较。使用MnlI酶未发现多态性，因为所有345个样本在位置605处均显示切割位点，所有山羊均为MM基因型。然而，使用RsaI酶时，一些撒丁岛山羊在位置53处显示出一个多态性位点。9只撒丁岛山羊为R/r基因型，仅在一个等位基因中缺少该切割位点，而其他动物，包括撒丁岛山羊和其他品种，在两个等位基因中均有切割位点，因此为R/R基因型。在任何品种中均未发现r/r基因型。在撒丁岛山羊中，R等位基因的等位基因频率为0.98，r等位基因的等位基因频率为0.02；R/R基因型的基因型频率为96.00%，R/r基因型的基因型频率为4.00%。统计分析显示（P<0.001）R/r基因型与繁殖活动之间存在紧密联系，繁殖活动受光周期的强烈影响。测序表明有六个核苷酸变化，但未引起任何氨基酸变化。数据表明存在多态性，且仅在撒丁岛品种中影响繁殖活动。
