二化螟dsRNA降解酶基因的克隆与表达分析

为解析二化螟Chilo suppressalis体内参与降解双链RNA(double-stranded RNA,dsRNA)的关键核酸酶的功能，克隆二化螟不同的非专一性核酸酶（non-specific nuclease,NUC）基因，并对这些基因进行生物信息学分析和组织定量表达分析，同时对dsRNA降解酶（dsRNA degrading nuclease,dsRNase）活力的组织分布进行研究。结果显示，共克隆获得5个NUC基因，其中有4个编码dsRNase亚家族基因（CsdsRNase1～CsdsRNase4）和1个编码Endonuclease G亚家族基因（CsEndoG）。5个NUC基因的开放阅读框核苷酸序列长度范围为828～1 338 bp，编码275～445个氨基酸残基，其分子量大小为31.68～49.57 kD，预测等电点为5.48～9.42。CsdsRNase1和CsdsRNase2含有信号肽序列，两者相似度极高，且与家蚕Bombyx mori和斜纹夜蛾Spodoptera litura中具有dsRNA降解酶活力的dsRNase同源聚类；CsdsRNase1和CsdsRN...

Cloning and expression analysis of double-stranded RNA degrading enzyme genes in the rice stem borer Chilo suppressalis

To elucidate the function of the key nucleases involved in the degradation of double-stranded RNA (dsRNA) in rice stem borer Chilo suppressalis, different non-specific nuclease (NUC) genes were cloned and subjected to bioinformatics analysis and tissue-specific expression analysis. The distribution of the activity of dsRNA degrading nucleases (dsRNase) in different tissues was also investigated. Five NUC genes were cloned, including four genes encoding the dsRNase subfamily (CsdsRNase1-CsdsRNase4) and one gene encoding the endonuclease G subfamily (CsEndoG). The open reading frames of the five NUC genes ranged from 828 to 1 338 bp, encoding 275 to 445 amino acid residues, with molecular weights ranging from 31.68 to 49.57 kD and predicted isoelectric points ranging from 5.48 to 9.32. CsdsRNase1 and CsdsRNase2 contained putative signal peptide sequences, and they shared high sequence identity. CsdsRNase1 and CsdsRNase2 were clustered in the same clade with dsRNase enzymes that showed dsRNA-degrading activity in Bombyx mori and Spodoptera litura. CsdsRNase1 and CsdsRNase2 were predominantly expressed in the midgut, consistent with the high distribution of dsRNA degrading activity in this tissue, indicating that these two genes might be key nucleases involved in dsRNA degradation in the midgut. The presence of multiple dsRNase gene sequences in C. suppressalis, especially CsdsRNase1 and CsdsRNase2, which were highly expressed in the midgut, might affect the stability of dsRNA, thereby affecting RNA interference efficiency.