RNA: guiding gene silencing.

In diverse organisms, small RNAs derived from cleavage of double-stranded RNA can trigger epigenetic gene silencing in the cytoplasm and at the genome level. Small RNAs can guide posttranscriptional degradation of complementary messenger RNAs and, in plants, transcriptional gene silencing by methylation of homologous DNA sequences. RNA silencing is a potent means to counteract foreign sequences and could play an important role in plant and animal development.