中文摘要：

对常年发情的绵羊品种小尾寒羊和季节性发情的绵羊品种多赛特羊共20只母羊的褪黑激素受体1A（melatonin receptor 1A,MTNR1A）基因外显子2的824 bp扩增产物进行了克隆测序及序列比较分析.结果表明,小尾寒羊MTNR1A基因外显子2的核苷酸序列与已发表的绵羊序列（GenBank登录号U14109）完全相同.小尾寒羊与多赛特羊MTNR1A基因外显子2的差异由5个变化的核苷酸（分别为C329T、G355T、C566T、C580A和A675G）组成,核苷酸同源性为99.4%.小尾寒羊与山羊、母牛、猪、人、小鼠、挪威大鼠、西伯利亚仓鼠和鸡之间MTNR1A基因外显子2的核苷酸序列同源性为73.2%～98.5%,氨基酸序列同源性为78.5%～98.5%.

英文摘要：

The 824 bp fragment of exon 2 of melatonin receptor 1A（MTNR IA ） gene was amplified successfully by PCR in both 10 ewes of nonseasonal estrous breed （Small Tail Han sheep） and 10 ewes of seasonal estrous breed （Dorset sheep）, and then cloned into pGEM-T Easy vector. The positive clones were further identified by PCR and sequenced. The nucleotide sequence of exon 2 of MTNRIA gene in Small Tail Han sheep was the same as that published in GenBank 0314109）. The differences in exon 2 of MTNRIA gene between Small Tail Hart sheep and Dorset sheep consisted of five nucleotide changes （C329T, G355T, C566T, C580A and A675G）, and homology of nucleotide sequence was 99.4%. Homologies of nucleotide sequence and amino acid sequence of exon 2 of MTNRIA gene between Small Tail Han sheep and goat, cow, pig, human, house mouse, No＇rway rat, Siberian hamster and chicken were 73.2% to 98.5% and 78.5% to 98.5%, respectively.