Science / Medicine : Self-Replicating RNA Assembled

How did life originate in the pre-biotic world? Many scientists now envision a so-called RNA world in which life’s immediate precursors were strands of self-reproducing RNA, or ribonucleic acid, a DNA-like material that cells now use as a working blueprint in producing proteins.

The problem has been that no one has ever seen RNA that could replicate itself--at least until now. Molecular biologist Jennifer A. Doudna and her colleagues at Massachusetts General Hospital in Boston reported last week in the journal Science that they had assembled an RNA molecule that could catalyze its own synthesis.

They modified an RNA fragment from a bacteriophage, a virus that infects bacteria, and found that three of the resulting fragments could bind together to form a molecule that was able to synthesize each of the fragments from starting materials that might have been available in the pre-biotic world.

“Our experiments suggest that the spontaneous assembly of the first RNA replicases (molecules that reproduce themselves) from pre-biotically produced RNA might not have been as difficult as imagined,” they concluded.