RNAi for the masses: Ambion and New England Biolabs offer in vitro transcription-based kits for construction of dsRNAs. (Tools & Technology).

RNA interference (RNAi), discussed previously in The Scientist, (1) is a post-transcriptional, targeted gene-silencing technique that uses double-stranded RNA (dsRNA) to degrade messenger RNA (mRNA) containing the same sequence as the dsRNA. The process occurs in at least two steps: an endogenous ribonuclease cleaves the longer dsRNA into shorter, 21-or 22-nucleotide-long RNAs, termed "small interfering RNAs" or siRNAs. The smaller RNA segments then mediate the degradation of the target mRNA. (2) Recently, RNAi has been used for gene function determination in a manner similar to anti-sense oligonucleotides.

Long dsRNAs have been used successfully for RNAi studies in Drosophila and Caenorhabditis elegans, but RNA …