Department of Plant and Soil Science, University of Kentucky, Lexington, KY 40546, USA.
Formulation Technology Group, Syngenta, Jealotts Hill international Research Centre, Bracknell, Berkshire RG42 6EY, UK.
Pestic Biochem Physiol. 2021 Aug;177:104906. doi: 10.1016/j.pestbp.2021.104906. Epub 2021 Jun 24.
The response of insects to orally delivered double-stranded RNA ranges widely among taxa studied to date. Long dsRNA does elicit a response in stink bugs but the dose required to achieve an effect is relatively high compared to other insects such Colorado potato beetle or western corn rootworm. Improving the delivery of dsRNA to stink bugs will improve the likelihood of using RNA-based biocontrols for the management of these economically important pests. Short hairpin RNA (shRNA) is a useful molecule with which to test improvements in the delivery of double stranded RNA in the neotropical brown stink bug, Euschistus heros, since shRNA alone does not elicit a clear effect like that for long dsRNA. Here, we show for the first time the oral delivery of shRNA triggering RNA interference (RNAi) in E. heros using 4 nm cerium oxide nanoparticles (CeO NPs) coated with diethylamioethyl dextran (Dextran-DEAE) as a carrier. We identified particle properties (coating composition and degree of substitution, hydrodynamic diameter, and zeta potential) and shRNA loading rates (Ce:shRNA mass ratio) that resulted in successful transcript reduction or RNAi. When the Z-average diameter of CeO Dextran-DEAE-shRNA NP complex was less than 250 nm and the zeta potential was in the 15-25 mV range (Ce:shRNA mass ratio of 0.7:1), significant mortality attributed to RNAi was observed with a shRNA concentration in feeding solution of 250 ng/μl. The degradation of the targeted troponin transcript by NP-delivered shRNA was equivalent to that observed with long dsRNA, while naked shRNA transcript reduction was not statistically significant. Elemental mapping by synchrotron X-ray fluorescence microprobe confirmed uptake and distribution of Ce throughout the body with the highest concentrations found in gut tissue. Taken together, our results suggest that a nanoparticle delivery system can improve the delivery of RNA-based biocontrols to E. heros, and therefore its attractiveness as an application in the management of this important pest in soybean production.
昆虫对口服双链 RNA 的反应在迄今为止研究的分类群中差异很大。长 dsRNA 确实会引起盲蝽科昆虫的反应，但与其他昆虫（如科罗拉多马铃薯甲虫或西部玉米根虫）相比，达到效果所需的剂量相对较高。提高 dsRNA 向盲蝽科昆虫的递送效率将提高基于 RNA 的生物防治措施用于管理这些经济上重要的害虫的可能性。短发夹 RNA (shRNA) 是一种有用的分子，可用于测试在新热带棕色盲蝽 Euschistus heros 中提高双链 RNA 递送的效果，因为单独的 shRNA 不会像长 dsRNA 那样引起明显的效果。在这里，我们首次展示了使用 4nm 氧化铈纳米粒子 (CeO NPs) 作为载体，用二乙氨基乙基葡聚糖 (Dextran-DEAE) 包裹，通过口服递送 shRNA 触发 E. heros 中的 RNA 干扰 (RNAi)。我们确定了颗粒特性（涂层组成和取代度、水动力学直径和 zeta 电位）和 shRNA 加载率（Ce:shRNA 质量比），这些特性导致成功的转录减少或 RNAi。当 CeO Dextran-DEAE-shRNA NP 复合物的 Z 均直径小于 250nm，zeta 电位在 15-25mV 范围内（Ce:shRNA 质量比为 0.7:1）时，在用 250ng/μl 的喂食溶液中观察到浓度时，会观察到归因于 RNAi 的显著死亡率。NP 递送的 shRNA 对靶肌钙蛋白转录本的降解与长 dsRNA 观察到的降解相当，而裸露 shRNA 转录本减少则没有统计学意义。同步加速器 X 射线荧光微探针的元素映射证实了 Ce 被整个生物体吸收和分布，在肠道组织中发现了最高浓度。总之，我们的结果表明，纳米颗粒递送系统可以提高 RNA 生物防治措施向 E. heros 的递送效率，因此，作为在大豆生产中管理这种重要害虫的应用，其吸引力增加。
