Scientists are announcing a breakthrough in determining the origin of life on Earth – and perhaps on Mars

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Scientists from the Foundation for Applied Molecular Evolution announced today that ribonucleic acid (RNA), an analog of DNA that is probably the first genetic material for life, spontaneously forms on basaltic lava glass. Such glass was abundant on Earth 4.35 billion years ago. Similar basalts from this antiquity survive on Mars today.

“Communities studying the origins of life have diverged in recent years,” said Stephen Banner, co-author of the study, published online in the journal astrobiology.

“A community is revisiting the classic issues with complex chemical schemes that require difficult chemistry performed by experienced chemists,” Banner explained. “Their beautiful crafts appear in magazines with brands such as nature and science“However, precisely because of the complexity of this chemistry, it cannot explain how life on Earth actually came into being.

In contrast, the Foundation’s study uses a simpler approach. Led by Elisa Biondi, the study shows that long RNA molecules 100-200 nucleotides in length are formed when nucleoside triphosphates do nothing more than seep through basalt glass.

“Basalt glass was everywhere on Earth at the time,” said Stephen Moses, an earth scientist who is also involved in the study. “For several hundred million years after the formation of the moon, frequent blows, combined with abundant volcanism on the young planet, formed molten basaltic lava, a source of basalt glass. The shocks also evaporated the water to give dry land, providing aquifers where RNA could form. “

The same effects are provided by nickel, which the team showed gave nucleoside nucleoside triphosphates and activated phosphate, also found in lava glass. Borate (as in borax), also from basalt, controls the formation of these triphosphates.

The same impact elements that formed the glass also temporarily reduced the atmosphere with their metallic iron-nickel cores. In such atmospheres, RNA bases are formed, the sequences of which store genetic information. Earlier, the team showed that nucleosides are formed by a simple reaction between ribose phosphate and RNA bases.

“The beauty of this model is its simplicity. It can be tested by high school students in a chemistry class, “said Jan Spacek, who was not involved in the study but is developing a tool to detect extraterrestrial genetic polymers on Mars. “Mix the ingredients, wait a few days and find the RNA.”

The same scales resolve other paradoxes in the creation of RNA along the path that travels all the way from simple organic molecules to the first RNA. “For example, borate controls the formation of ribose, ‘R’ in RNA,” Banner added. This time it starts with simple carbohydrates that “can’t help but” formed in the atmosphere above primitive Earth. They were stabilized by volcanic sulfur dioxide and then rained to the surface to form reservoirs of organic minerals.

Thus, this work completes the pathway that creates RNA from small organic molecules that were almost certainly present on early Earth. A single geological model is driven by one and two carbon molecules to give RNA molecules long enough to sustain Darwinian evolution.

“Important questions remain,” Banner warned. “We still don’t know how all the building blocks of RNA came to the same common form, a bond known as homogeneity.” Similarly, nucleotide linkages may be variable in the material synthesized on basalt glass. The import of this is not known.

Mars is important for this message, as the same minerals, glasses and influences have been present on Mars since ancient times. However, Mars has not suffered continental drift and plate tectonics, which have buried most of the rocks on Earth older than 4 billion years. Thus, rocks from the relevant time remain on the surface of Mars. Recent missions to Mars have found all the necessary rocks, including borate.

“If life appeared on Earth in this simple way, then it probably appeared on Mars,” Banner said. “That makes it even more important to look for life on Mars as soon as possible.”

A meteorite on Mars shows evidence of a massive impact billions of years ago

More info:
Craig A. Jerome et al, Catalytic synthesis of polyribonucleic acid on prebiotic rock glasses, astrobiology (2022). DOI: 10.1089 / ast.2022.0027

Hyo-Joong Kim et al, Prebiotic stereoselective synthesis of purine and non-canonical pyrimidine nucleotide from nucleobases and phosphorylated carbohydrates, Notices of the National Academy of Sciences (2017). DOI: 10.1073 / pnas.1710778114

Hyo-Joong Kim et al, Prebiotic synthesis of canonical pyrimidine and purine ribonucleotides, astrobiology (2019). DOI: 10.1089 / ast.2018.1935

Provided by the Foundation for Applied Molecular Evolution

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