From left, Mike Karberg, Alan Lambowitz, and Huatao Guo

Usually considered useless stretches of bases, introns are removed from RNA before it is translated into a protein. Now Alan Lambowitz, director of the Institute for Cellular and Molecular Biology at the University of Texas, and his colleagues have put group II introns to good use (H. Guo et al., "Group II introns designed to insert into therapeutically relevant DNA target sites in human cells," Science, 289:452-7, July 21, 2000). Eventually the researchers hope to use introns instead of gene therapy vectors to introduce beneficial genes or disrupt harmful genes in patients. Excised group II introns, found only in bacteria and in organelles of plants, yeast, and fungi, exist in a ribonucleoprotein (RNP) complex with a reverse transcriptase protein that is encoded by the intron. With the help of the RNP complex and cellular machinery, the excised intron RNA...