斜纹夜蛾两个天蚕素D基因的克隆及序列分析

天蚕素是昆虫抵御病菌入侵的一类抗菌肽家族。根据斜纹夜蛾Spodoptera litura天蚕素B基因设计特异引物，通过PCR扩增得到2个新的天蚕素基因部分序列，分别命名为cecD1和cecD2（GenBank登录号分别为EF555567和EF555568）。2个基因编码同一个天蚕素D蛋白，该蛋白的成熟肽与天蚕素B存在2个氨基酸残基差异。序列分析发现cecD1和cecD2中分别包含568 bp和377 bp的内含子序列，它们有相同的5′和3′拼接位点，A+T含量分别为59.7%和69.8%，符合大多数真核生物内含子高A+T含量的特征。

Cloning and sequence analysis of two cecropin D genes from the common cutworm, Spodoptera litura ( Lepidoptera: Noctuidae)

Cecropins are a family of antibacterial peptides synthesized in insects as a response to a bacterial infection. Two primers were designed according to cecropin B gene from Spodoptera litura and were used to PCR. As the result, two new cecropin genes, named cecD1 and cecD, were obtained, which encoded identical preprocecropin D. There was 2 amino acid residues difference between the mature peptide of preprocecropin D and that of cecropin B from S. litura. Two introns, 568 bp and 377 bp long, were found in cecD1 and cecD2, respectively, both having the same 5′and 3′splicing sites. The A+T content was 59.7% in cecD1 intron and 69.8% in cecD2 intron, conforming to the high A+T content characteristics of most eukaryotic introns.