RNAi efficiency in insects is different from species to species; some species in Coleoptera are relatively more amenable to RNA interference (RNAi) than other species. One of the major factors is the presence of dsRNA-degrading enzymes, called dsRNases, in saliva, gut, or hemolymph in insects, which degrade the double-stranded RNA (dsRNA) introduced, resulting in the low efficacy of RNAi. In this study, we report a dsRNA-degrading activity in the gut homogenates from the spotted-wing drosophila, Drosophila suzukii, by ex vivo assay. Then, we identified two Drosophila suzukii dsRNase genes, named DrosudsRNase1 and DrosudsRNase2. In silico analysis shows that the gene structures are similar to dsRNases found in other insects. When dsRNases expressed in Sf9 cells were compared for their dsRNA degrading activities, dsRNase1 was more vital than dsRNase2. Both dsRNases were expressed highly and exclusively in the gut compared to the rest of body. Also, they were highly expressed during larval and adult stages but not in embryonic and pupal stages, suggesting the dsRNases protect foreign RNA molecules received during the feeding periods. DsRNase1 was expressed at a higher level in adults, whereas dsRNase2 showed more expression in early larvae. Our study on the tissue and development-specific patterns of dsRNases provides an improved understanding of the RNAi application for the management of D. suzukii.

中文翻译：

---

斑翅果蝇 Drosophila suzukii dsRNases 的鉴定及功能分析

昆虫的 RNAi 效率因物种而异；鞘翅目中的一些物种比其他物种更容易受到 RNA 干扰 (RNAi) 的影响。主要因素之一是昆虫的唾液、肠道或血淋巴中存在 dsRNA 降解酶，称为 dsRNases，它们降解引入的双链 RNA (dsRNA)，导致 RNAi 的效率低下。在这项研究中，我们通过离体测定报告了斑点翅果蝇Drosophila suzukii肠道匀浆中的 dsRNA 降解活性。然后，我们鉴定了两个Drosophila suzukiidsRNase 基因，命名为 DrosudsRNase1 和 DrosudsRNase2。计算机分析表明，基因结构与在其他昆虫中发现的 dsRNases 相似。当比较 Sf9 细胞中表达的 dsRNases 的 dsRNA 降解活性时，dsRNase1 比 dsRNase2 更重要。与身体的其他部分相比，这两种 dsRNase 都在肠道中高度且专门地表达。此外，它们在幼虫和成虫阶段高度表达，但在胚胎和蛹阶段不表达，这表明 dsRNases 保护在喂养期间收到的外源 RNA 分子。DsRNase1 在成虫中的表达水平较高，而 dsRNase2 在早期幼虫中的表达水平较高。我们对 dsRNases 的组织和发育特异性模式的研究提供了对 RNAi 应用的更好理解D.铃木。