Researchers in Germany have uncovered evidence suggesting that the earliest forms of life may have benefited from the frozen environment of the polar regions. 

Clemens Richert and Stephanie Vogel of the University of Karlsruhe have found that spontaneous replication steps of RNA molecules in the absence of the usual enzymes is possible, even for the most 'difficult' sections of the strand. 'The notion of spontaneous replication, perhaps the very reaction that defines the beginning of life from inanimate material, is fascinating. All attempts to demonstrate this phenomenon in vitro have thus far failed,' he said. 

In today's cells, this nucleic acid replication requires catalysis by polymerases, but at some point in prebiotic evolution, replication must have begun without these enzymes. 'It is likely that RNA was the first encoding system, as the biopolymer itself forms catalysts (ribozymes) for a primitive kind of metabolism,' he asserted. According to Richert, the key problem for RNA is that certain stretches of sequence consisting of multiple adenosine (A) residues do not support spontaneous replication. 

Replication of the RNA in Richert's system is assisted by three factors: an oxyazabenzotriazolide monomers to promote nucleotide extension, short 'helper' strands which assists the growing strand in covering the difficult gap posed by multiple A residues, and the low temperature which helps to improve the yield of copied nucleotide. Even in their 'worst case' situation, a stretch of three A residues, the right conditions allowed successful enzyme-free replication in a frozen mixture. 'Together these measures lead to successful replication steps instructed by sequences that were previously thought to be complete blocks to replication,' added Richert. 

He continued: 'The current findings are only one step towards full spontaneous replication of RNA from mononucleotides. A system that causes the monomers to 'zipper up' completely from one end of the original strand to the other, followed by dissociation of the new strand from the original is not yet within our reach.' 

Michael Spencelayh