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Long strands of RNA created using only warm water

Erin Podolak

Italian researchers have generated long strands of RNA by replicating the conditions on early earth, proving that ancient organic molecules could have given rise to modern RNA.

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Researchers at the University of Rome are one step closer to understanding the origin of life on earth. Led by professor of genetics and molecular biology, Ernesto Di Mauro, the researchers created long strands of RNA using only molecules that could have existed on primordial earth. Scientists have long suspected that RNA was one of the earliest biological molecules present on ancient earth, predating DNA and proteins, but until now have failed to replicate its creation.

“The unsophisticated chemistry required for the formation of both open and cyclic nucleotides prompted us to investigate the possibility of their spontaneous polymerization,” said the authors in a paper published Nov. 27 in the Journal of Biological Chemistry. “If so nonenzymatic (pre)genetic polymerization could have taken place in ‘warm little pond’ conditions, close to those imagined by Darwin.”

Primordial RNA assembled without the help of enzymes. Source: Wikipedia Commons.

RNA typically grows longer by adding one nucleic base at a time, like a sequential chain. However, “In primordia, RNA molecules had no enzymes to catalyze their chain-wise growth, and highly activated precursors can be considered as prebiotic only with difficulty,” said the authors. According to a press release, RNA growth can occur naturally, but the rate is so slow that RNA strands would never have grown to more than a few bases long. For several years, Di Mauro’s team has been experimenting with water temperatures to try to determine the perfect conditions for assembling nucleotides.

The team has reportedly found the right balance for RNA creation in water ranging in temperature from 40°C to 90°C. At these temperatures, ancient molecules called cyclic nucleotides 10-14 bases long will join together and begin to form polymers after just 14 hours, reaching over 100 nucleotides in length over the course of approximately 200 hours. Reaching this length is significant because at around 100 bases long, RNA molecules can begin to fold into functional 3-D shapes.

Cyclic nucleotides, like cyclic-AMP, are similar to the nucleotides that make up individual pieces of RNA and DNA. However, cyclic nucleotides form an extra chemical bond, assuming a ring-shaped structure that makes cyclic nucleotides more reactive. Simple chemicals such as formamide can be used to form cyclic nucleotides, which make it plausible that cyclic nucleotides would have existed on primordial earth and could have given rise to the first RNA molecules.

“Generation of long RNA chains in water,” was published Nov. 27 online at the Journal of Biological Chemistry.