Small Organism, No Small Feat

Adding some complexity to the seemingly simple life of a single-celled organism, researchers have found that a green alga uses snippets of RNA to control its genes. The finding, the first "microRNAs" outside of the multicellular world of plants and animals, indicates that simple organisms can regulate genes in ways similar to their more advanced counterparts. MicroRNAs, or miRNAs, are chains of about two dozen nucleotides--peewees to most RNAs in a cell--bent into a hairpin shape. In the last six years, researchers have discovered that these elements control the expression of genes in animals and plants (Science, 26 October 2001, p. 797). In both kingdoms, the miRNA interacts with the protein-coding messenger RNA strand, but in different ways: In animals, it stops the template from getting read past a certain point, whereas in plants it cleaves the strand. MiRNAs were known to control the development of animals and plants, but because they hadn't been found in simpler creatures, it wasn't clear if they emerged after multicellular organisms evolved.... Whole article "www.sciencenow.sciencemag.org":[ www.sciencenow.sciencemag.org]

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