Silencing of Toll pathway components by direct injection of double-strated RNA into Drosophila adult flies. Nucleic Acids Research

Double-stranded RNA (dsRNA) gene interference is an ef®cient method to silence gene expression in a sequence-speci®c manner. Here we show that the direct injection of dsRNA can be used in adult Drosophila ¯ies to disrupt function of endogenous genes in vivo. As a proof of principle, we have used this method to silence components of a major sig-naling cascade, the Toll pathway, which controls fruit ¯y resistance to fungal and Gram-positive bac-terial infections. We demonstrate that the knockout is ef®cient only if dsRNA is injected in 4- or more day-old ¯ies and that it lasts for at least 1 week. Furthermore, we report dsRNA-based epistatic gene analysis via injection of a mixture of two dsRNAs and propose that injection of dsRNA represents a powerful method for rapid functional analysis of genes in Drosophila melanogaster adults, particu-larly of those whose mutations are lethal during development