中文摘要：

【目的】为了在猪中找到更多新的候选印记基因并分析它们在哺乳动物之间的保守性,以期为猪分子遗传育种提供基础分子生物学信息和分子标记。【方法】以长白与荣昌猪杂交F1代一月龄个体为研究对象,通过比较生物学的方法,克隆COPG2和MEST全长cDNA,并分析基因的序列特点,然后利用IMpRH（法国农业科学院的辐射杂种克隆板）分析COPG2和MEST在猪染色体上定位信息。通过RT-PCR产物直接测序方法分析了这些基因在一月龄F1代个体11个不同组织（心、胃、肌肉、肾脏、肺、肝、小肠、膀胱、舌头、脾和脂肪）的印记状况,并进一步利用Real-timePCR方法,分析其在一月龄F1代个体11个不同组织的表达情况。【结果】克隆得到2817bp COPG2和2219bp MEST序列。其中COPG2包括2616bp完整CDS（coding sequenc,编码序列）区域,分析表明其编码含871个氨基酸的蛋白质,MEST包括981bp完整CDS区域,编码326个氨基酸的蛋白质。IMpRH分析结果表明,猪COPG2和MEST都位于猪18号染色体上并且与标记CL365941紧密连锁,LOD值分别为14.32和8.5。印记分析表明COPG2在11个组织中呈双等位表达,MEST在心脏、胃、肌肉、肾、肺、膀胱、舌头和脂肪中表达父方等位基因,但在肝脏、小肠和脾脏中呈双等位表达。荧光定量结果显示COPG2和MEST总的表达量在一月龄个体各组织间存在着显著性差异（P〈0.01）,其中COPG2和MEST在肾脏中表达量均高于其它各组织（P〈0.01）。【结论】在哺乳动物之间,COPG2序列较为保守但是印记状况却缺乏保守性;MEST序列和印记状况均较为保守,但MEST在猪中印记状况具有组织特异性。此外,染色体定位信息和印记状况证实了在猪的18号染色体上有由COPG2和MEST构成的新的印记域。

英文摘要：

【Objective】 In order to find more novel candidate imprinted genes in pigs and assess their conservation among mammalian species and provide the basic molecular biology information and molecular markers for procine molecular genetics and breeding,comparative biology method was used to study porcine COPG2 and MEST genes.【Method】 The porcine COPG2 and MEST genes from the one-month-old F1 hybrid pigs,between Rongchang and Landrace were cloned and sequenced,and then its molecular features were analyzed.Mapping of the porcine COPG2 and MEST genes to porcine chromosome were made with the IMpRH panel.Through the direct sequencing of the RT-PCR products,the imprinting status of both genes in 11 different tissues of one-month-old F1 heterozygotes were analyzed.The mRNA distribution of the porcine COPG2 and MEST genes in 11 different tissues（heart,stomach,skeletal muscle,kidney,lung,liver,small intestine,bladder,tongue,spleen and fat） were examined by real-time PCR.【 Result】 Two sequences with the full-length of 2 817 bp for COPG2 gene and 2 219 bp for MEST gene were cloned.COPG2 and MEST contain coding sequence of 2 616 bp and 981 bp,encoding proteins of 871 and 326 amino acid residues,respectively.By the IMpRH panel,porcine COPG2 and MEST genes were assigned to porcine chromosome 18,and closely linked with CL365941 with the LOD of 14.32 and 8.5,respectively.Imprinting analysis demonstrated that COPG2 was biallelically expressed in 11 tissues examined and MEST was paternally expressed in heart,stomach,skeletal muscle,kidney,lung,bladder,tongue and fat,while biallelically expressed in liver,small intestine and spleen.Real-time PCR results showed that the expression level of porcine COPG2 and MEST were significantly different among tissues of one-month-old pig（P0.01）.Both the COPG2 and MEST genes showed the highest expression levels in the kidney than all of the other tissues.【Conclusion】 The sequence of COPG2 is conservative,but the imprinting status is not conservative among mammalian species.For ME