The amazing travels of small RNAs

Biologists have known for some time that RNA interference can silence genes in far-off cells. They suspected that a messenger substance "transmits" RNA interference. Now, ETH researchers have definitively shown that these messengers in plants are short double-stranded RNA fragments. In most organisms, small bits of RNA play a key role in gene regulation by silencing gene expression. They do this by targeting and docking onto complementary sequences of gene transcripts (also RNA molecules), which stops the cell machinery from using them to make proteins. This mechanism is called RNA interference (RNAi), and it is critically important in biology. Remarkably, the RNAi phenomenon is not necessarily confined to single cells; it can also manifest in other tissues and organs far away from the cell of origin.