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Proc Natl Acad Sci U S A,
2003]
The discovery of transgene silencing in plants and double-stranded RNA (dsRNA) interference in the worm Caenorhabditis elegans has led to the latest revolution in molecular biology, RNA interference (RNAi). Over 10 years ago it was noted that several transgenic plant lines each containing the same ectopic transgene not only failed to be expressed but also inhibited the expression of the endogenous gene. Similarly, a determined Craig Mello and Andy Fire, attempting to reduce gene function using using antisense RNA in the worm, discovered a minor contaminant in their antisense RNA preparation effectively and repeatedly reduced expression of the endogenous gene. In both cases, dsRNA homologous to the gene of interest was responsible for these observations. In the last 4 years, these discoveries have been extended to include protozoa,