野桑蚕酚氧化酶原基因cDNA的分子克隆及其特征

摘要

Phenoloxidase plays an important role in defense mechanisms in insect immunity.The complemental deoxyribonucleic acid(cDNA)of Bombyx mandarins prophenoloxidase(PPO)gene was cloned by means of reverse transcription polymerase chain reaction(RT-PCR)and rapid amplification of cDNA ends(RACE).The cDNA was 2 134 bp in length and contained an open reading frame(ORF)of 2 082 bp which eneoded 693 amino acid residues.The deduced amino acid sequence showed a high identity to the reported sequence of PPO2 from other Lepidopterous insects and shared the typical structural features of PPO from other inseets.The results of RT-PCR showed that PPO mRNA was expressed in the integument,haemocyte,head,testis,ovary,fat body and midgut of 5th instar larvae and at different developmental stages of B.mandarina.These results provide molecular basis for further studying the function of ppo gene in B.mandarina.%酚氧化酶在昆虫的免疫防御机制中起着重要作用.利用RT-PCR和RACE方法,克隆了野桑蚕酚氧化酶原基因,获得了其cDNA序列.该序列长2 134 bp,含有一个2 082 bp的完整开放阅读框,编码一个由693个氨基酸残基组成的蛋白质.推导的氨基酸序列与其他鳞翅目昆虫PP02基因相应氨基酸序列有较高的同源性,该序列具有它们的PPO基因所共有的典型特征.组织特异性表达分析表明了该基因在野桑蚕5龄幼虫的血细胞、体壁、头部、精巢、卵巢、脂肪体和中肠等组织及其不同的发育阶段均有表达.这些结果为进一步研究野桑蚕酚氧化酶原基因的功能提供了分子基础.