An RNA Microcosm

A year ago came the suprising discovery that animals have perhaps hundreds of micro-RNAs (miRNAs). Now the importance of miRNA in plants and animals is being revealed. In his perspective, [Baulcombe][1] describes new work ([Llave][2] et al .; [HutvAigner and Zamore][3]) that gives insight into how miRNA and related small RNAs may control processes as diverse as translational arrest, RNA cleavage, and genome rearrangement. [1]: http://www.sciencemag.org/cgi/content/full/297/5589/2002 [2]: http://www.sciencemag.org/cgi/content/short/297/5589/2053 [3]: http://www.sciencemag.org/cgi/content/short/297/5589/2056