家蝇幼虫防御素基因的克隆和序列分析

目的：克隆家蝇幼虫防御素（defensin）基因并进行序列分析。方法：根据Genbank公布的家蝇成虫defensin基因序列设计一对引物,以家蝇幼虫基因组DNA为模板,进行PCR扩增、测序,并利用软件进行序列分析。结果：克隆得到的defensin基因的长度为330bp,编码92个氨基酸,4个阳性克隆的DNA序列编码的多肽在第27位氨基酸残基不同,为K或N。结论：从家蝇幼虫基因组DNA中克隆得到了defensin基因,发现了两种相差一个氨基酸残基的defensin前体蛋白,并初步预测了两种前体蛋白的化学性质和二级结构,为该基因的重组表达奠定了基础。

Cloning and Sequence Analysis of Defensin Genes from Musca domestica Larva

Objective：To clone the defensin genes of Musca domestica larvae and analyze their sequences.Methods：PCR was carried out to obtain the gene fragment with the genomic DNA of M.domestica larvae as template,and the primers used were designed following M.domestica adult defensin gene sequence in Genbank.The PCR products were purified and cloned into plasmid T-vector,and sequenced.Results：The amplified products were about 330bp,and were deduced to encode 92 amino acids.Five Single Nucleotide differences of sequences exited among four clones.Two kinds of deduced amino acid sequences of defensin gene were gained from M.domestica larvae in this experiment.Conclusion：Defensin gene of M.domestica larvae has been cloned successfully.Two kinds of defensin precursor proteins were found,which lays foundation for further research on recombinant defensin expression and its antibiotic activety.