中文摘要：

为了探讨犬免疫球蛋白IgM所包含的生物学信息及其与其他物种的亲缘和进化关系,对犬IgM重链恒定区进行了研究。采用3′RACE及RT-PCR方法,获得了犬IgM重链恒定区全长基因（包括分泌型和跨膜型）,犬具有哺乳动物IgM的典型特征,其恒定区包括CH1-CH4 4个区,其中CH3与CH4区序列相对保守,分泌尾的同源性更高,靠近分子的羧基端同源性有增加的趋势。种系发生树分析发现,犬与大熊猫及猫等食肉目动物位于一个进化树分支上。DNAMAN软件分析显示,犬与大熊猫和猫的核酸序列同源性分别为87.88%和81.58%。

英文摘要：

To analyze the immunoglobulin IgM heavy chain constant regions of dog for its bioinformatics and evolution relation with other species, by 3＇RACE and RT - PCR methods, we obtained dog IgM constant region complete length sequences including the functional secreted and transmembrane form tails. The dog had typical mammalian IgM characteristics. According to the analysis of sequences, the constant region included four sub-regions （CH1-CH4）, attached two types of tails, of which CH3 and CH4 subregions had the higher identity. Conservation increased towards carboxyl terminus of dog IgM constant region . A comparative analysis of the nucleotide sequences for IgM from various animal species showed that dog IgM, within the various animals studied, is the closest to panda and cat in evolution.