DNA Doubled

Naturally occurring DNA consists of four building blocks, or nucleotides, spelled out by the letters G, C, A and T. Scientists have calculated that, in theory, other 'letters' chemically similar to the existing four are capable of integrating into DNA molecules. But, for whatever reason, evolution did not choose them. Putting that theory to the test, researchers have now shown that indeed four of these alternative nucleotides (Z, P, S and B) can, together with G, C, A and T, form DNA molecules with double the genetic alphabet. This synthetic DNA looks and behaves like the real thing. The video shows a molecular model of the eight-letter DNA with a standard double-helix structure – and can even be used to make eight-letter RNAs – DNA-encoded molecules with catalytic capabilities. By creating RNAs with novel nucleotides, the potential functions of these molecules have vastly increased, as have their potential biotechnological and medical applications.

Written by Ruth Williams

Ruth Williams

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Ruth is a freelance science journalist based in the US. She's a regular correspondent for The Scientist, and her work has appeared in The Lancet, Nature, Scientific American Mind, BBC Focus and elsewhere. Twitter @rooph

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• Video by Millie Georgiadis, Indiana University School of Medicine
• Foundation for Applied Molecular Evolution, Alachua, FL, USA
• Video copyright held by the authors
• Research published in Science, February 2019