RESOURCES: Molecular Outtakes

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Science  20 Feb 2004:
Vol. 303, Issue 5661, pp. 1115
DOI: 10.1126/science.303.5661.1115b

In a human cell, a cadre of molecules snips and splices a would-be messenger RNA to make a functional version. But in many organisms, unwanted RNA segments can remove themselves. These so-called group II introns, which occur in bacteria and archaea and in the chloroplasts and mitochondria of some eukaryotes, chop themselves out of an RNA molecule and help reseal the severed strand. Researchers looking for more information on these self-editing segments should check out this newly revised site, created by molecular biologist Steven Zimmerly's lab at the University of Calgary in Canada.

The nimble RNA segments could be the ancestors of the noncoding regions in the genes of animals and plants. Because many researchers don't recognize them, Zimmerly compiled a table that lists all the group II introns that have turned up in sequenced bacterial genomes—more than 100 so far. Users can nab data such as the intron's sequence and structure and the sequence of adjacent segments. Some group II introns code for proteins that help them slip into a strand of DNA, and the table also provides information on these proteins.

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