August 1, 2008 (Vol. 28, No. 14)
Strong Points: Descriptions
Weak Points: Too narrow
Speaking of RNA modifications, RNA editing, a subset of the phenomenon, is a bizarre but simultaneously amazing topic. Known in organisms across the eukaryotic evolutionary tree, the process involves post-transcriptional modification of RNAs, usually to alter the coding of mRNAs, but other examples exist. This includes insertional events (kinetoplastid and Physarum mitochondria), chemical modification (plant mitochondria and chloroplasts, as well as human intestines), and substitution editing in tRNAs (marsupial mitochondria). Remarkably, the changes brought by many of the modifications could probably more easily evolve by simply mutating the DNA as necessary. Why, then, does such a system exist? That’s a bigger question than I’ll try to answer here, but I will point readers to the informative RNA Editing Website, hosted by Larry Simpson at UCLA, where they can read about all these alterations and also meander from there through other sites of the RNA Webring, of which the RNA Editing Website is a member.