The only cellular structures known to possess genomes are the nucleus, mitochondria and chloroplasts. Now researchers find that centrosomes, which help to oversee cell division, apparently possess their own genetic machinery—and curiously, it's not DNA but its cousin, RNA. Scientists collaborating at the Marine Biological Laboratory in Woods Hole, Mass., purified five RNA sequences from surf clam eggs. Though abundant in the centrosomes, few to no copies of these RNAs were found elsewhere in the cell, and their sequences were not seen in any genome database. One of the RNAs appears to encode machinery involved in replicating DNA and RNA, which suggests that centrosomes can duplicate their genetic material. Relatively little is known about the inner workings of centrosomes even after a century of study, and the investigators suggest their discovery could explain centrosome evolution and function. The work is online June 5 via the Proceedings of the National Academy of Sciences USA.
This article was originally published with the title "A Place for RNA" in Scientific American 295, 2, 32 (August 2006)