中国地方品种鸡白细胞介素2基因的克隆及遗传进化分析(英文)

Cloning and Genetic Evolution Analysis of chIL-2 Gene of Chinese Local Breeds

鸡白细胞介素 2 (chIL 2 )是近年来新发现的一类细胞因子 .根据Sundick等发表的鸡IL 2基因序列设计一对特异性引物 ,从ConA体外激活的脾淋巴细胞中提取mRNA ,通过RT PCR方法分别扩增和克隆了我国仙居鸡、丝羽乌骨鸡两个地方品种和艾维茵商品肉鸡IL 2cDNA .仙居鸡、丝羽乌骨鸡和艾维茵商品肉鸡IL 2基因的编码区均由 42 9nt组成 ,编码一个由 143个氨基酸组成的前体蛋白 .基因 5′端含有 17个核苷酸 ,3′端含有 2 85个核苷酸组成的非编码区 ,3′ UTR中含有 5个重复的“ATTTA”序列 .编码蛋白氨基酸与来自GenBank的Kestrel、Obese和SC品系的来杭鸡比较 ,氨基酸的突变主要发生在 2 8～ 3 2位 .而这一区域仙居鸡和丝羽乌骨鸡的编码氨基酸序列与Kestrel来杭鸡相同 ,艾维茵商品肉鸡与Obese和SC来杭鸡相同 .基因系统进化树分析表明 ,仙居鸡、丝羽乌骨鸡和Kestrel来杭鸡具有很近的亲缘关系 ,艾维茵商品肉鸡与Obese和SC来杭鸡具有很近的亲缘关系 .中国的药用鸡品种———丝羽乌骨鸡在非常保守的 13

Chicken counterpart of interleukin-2 (chIL-2) is discovered recently which shows great potential in immunotherapy and immunoadjuvant applications. In view of its immunomodulating effects and involvement in disease resistant traits, this study compared the sequence relatedness and the genetic evolution of chIL-2 genes of local breeds with other geographical isolates. The chIL-2 genes from two Chinese local breeds (Xianju and Silky) and a commercial broiler breed (Avian) were amplified and cloned from Con A-stimulated chicken spleen lymphocytes. Sequence comparison revealed a similar genetic organization among the breeds with a coding region of 429 bases, a 5'-terminal untranslated region (UTR) with 17 nucleotides in length and an UTR with 285 nucleotides with five repetitive sequence of ATTTA at 3'-terminal. The deduced amino acid sequences were compared with strains Kestrel, Obese and SC Leghorn chickens from GenBank. Results showed that Yianju, Silky and Kestrel breeds shared an identical chIL-2 gene while the chIL-2 from Avian commercial broiler, Obese and SC Leghorn chickens was identical. In addition, a hypermutation region between residue 28 to 32 was identified. Phylogenetic analysis grouped Xianju, Silky and Kestrel, and Avian, Obese and SC into a separate group. Furthermore, a mutation from glutamic acid (E) to glycine (G) was found at the conserved residue 133 in Chinese official chicken breed-Silky chicken.