Primordial RNA May Have Contained Inosine

The discovery that the adenosine derivative aids self-replication adds weight to the theory that life on Earth originated from a mixture of RNA molecules.

Written byCatherine Offord

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RNA might have incorporated inosine, a derivative of adenosine, in place of guanosine

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ABOVE: A primordial version of RNA might have incorporated inosine, a derivative of adenosine, in place of guanosine.
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The paper
S.C. Kim et al., “Inosine, but none of the 8-oxo-purines, is a plausible component of a primordial version of RNA,” PNAS, 115:13318–23, 2018.

Proponents of the RNA world theory argue that life on Earth originated from a mixture of self-replicating, information-storing molecules. But while researchers have discovered ways that RNA’s pyrimidine nucleosides, uridine and cytidine, could have formed in primordial conditions, they’ve had less success with the purine nucleosides adenosine and guanosine, casting the theory into doubt.

Biologist Jack Szostak’s lab at Harvard Medical School recently set out to test a new hypothesis: that compounds called 8-oxo-purines could have acted as substitutes for modern purines in primordial RNA. His team used an adenosine derivative, inosine, as a control.

Under early-Earth conditions, 8-oxo-purines turned out to perform poorly—RNA molecules containing ...

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Meet the Author

Catherine Offord
After undergraduate research with spiders at the University of Oxford and graduate research with ants at Princeton University, Catherine left arthropods and academia to become a science journalist. She has worked in various guises at The Scientist since 2016. As Senior Editor, she wrote articles for the online and print publications, and edited the magazine’s Notebook, Careers, and Bio Business sections. She reports on subjects ranging from cellular and molecular biology to research misconduct and science policy. Find more of her work at her website.
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