Intra-abdominal injection of double-stranded RNA into anesthetized adult Drosophila triggers RNA interference in the central nervous system

RNA interference (RNAi) is a gene silencing mechanism that can be triggered by introducing double-stranded RNA (dsRNA) into cells expressing the appro priate molecular machinery, which then degrades the corresponding endogenou s mRNA. RNA! can be used for determining gene function and creating functio nal 'knockout' organisms. Here we show for the first time that RNAi can be induced in adult fruit files by injecting dsRNA into the abdomen of anesthe tized Drosophila, and that this method can also target genes expressed in t he central nervous system (CNS). Two genes were targeted to investigate the effects of dsRNA injection on their mRNA content; lacZ transgene (expresse d either in the gut or in the CNS), and GM06434, the Drosophila homologue o f the C. elegans gene nrf (nose resistant to fluoxetine). Both the transgen e and the endogenous gene were successfully silenced in adult Drosophila by intra-abdominal injection of their respective dsRNA. We propose that our m ethod of RNAi in adult flies can be used to characterize gene functioning i n the CNS without the typical interference in development found in most gen e mutation studies.