Supply of exogenous dsRNA (exo-dsRNA), either by injection or by feeding, is a fast and powerful alternative to classical knockout studies. The biotechnical potential of feeding techniques is evident from the numerous studies focusing on oral administration of dsRNA to control pests and viral infection in crops/animal farming. We aimed to dissect the direct and indirect effects of exo-dsRNA feeding on the endogenous short interfering RNA (endo-siRNA) populations of the free-living ciliate Paramecium. We introduced dsRNA fragments against Dicer1 (DCR1), involved in RNA interference (RNAi) against exo- and few endo-siRNAs, and an RNAi unrelated gene, ND169. Any feeding, even the control dsRNA, diminishes genome wide the accumulation of endo-siRNAs and mRNAs. This cannot be explained by direct off-target effects and suggests mechanistic overlaps of the exo- and endo-RNAi mechanisms. Nevertheless, we observe a stronger down-regulation of mRNAs in DCR1 feeding compared with ND169 knockdown. This is likely due to the direct involvement of DCR1 in endo-siRNA accumulation. We further observed a cis-regulatory effect on mRNAs that overlap with phased endo-siRNAs. This interference of exo-dsRNA with endo-siRNAs warrants further investigations into secondary effects in target species/consumers, risk assessment of dsRNA feeding applications, and environmental pollution with dsRNA.

中文翻译：

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喂食外源 dsRNA 会干扰草履虫中内源 sRNA 的积累。

通过注射或喂食提供外源 dsRNA (exo-dsRNA) 是经典基因敲除研究的一种快速而强大的替代方法。喂养技术的生物技术潜力从大量研究中显而易见，这些研究侧重于口服 dsRNA 以控制作物/动物养殖中的害虫和病毒感染。我们的目的是剖析 exo-dsRNA 对自由生活的纤毛虫草履虫的内源性短干扰 RNA (endo-siRNA) 种群的直接和间接影响。我们引入了针对 Dicer1 (DCR1) 的 dsRNA 片段，参与针对外切和少数内切 siRNA 的 RNA 干扰 (RNAi)，以及 RNAi 无关基因 ND169。任何喂食，甚至是对照 dsRNA，都会减少基因组范围内 endo-siRNA 和 mRNA 的积累。这不能用直接的脱靶效应来解释，并表明外切和内切 RNAi 机制的机械重叠。然而，与 ND169 敲低相比，我们观察到 DCR1 喂养中 mRNA 的下调更强。这可能是由于 DCR1 直接参与了 endo-siRNA 的积累。我们进一步观察到对与定相内切 siRNA 重叠的 mRNA 的顺式调节作用。exo-dsRNA 对 endo-siRNA 的这种干扰需要进一步研究目标物种/消费者的二次效应、dsRNA 喂养应用的风险评估以及 dsRNA 的环境污染。我们进一步观察到对与定相内切 siRNA 重叠的 mRNA 的顺式调节作用。exo-dsRNA 对 endo-siRNA 的这种干扰需要进一步研究目标物种/消费者的二次效应、dsRNA 喂养应用的风险评估以及 dsRNA 的环境污染。我们进一步观察到对与定相内切 siRNA 重叠的 mRNA 的顺式调节作用。exo-dsRNA 对 endo-siRNA 的这种干扰需要进一步研究目标物种/消费者的二次效应、dsRNA 喂养应用的风险评估以及 dsRNA 的环境污染。