How do the first fragments of life on Earth appear? The researchers proposed a new hypothesis

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Scientists have long sought to determine how life arose on Earth, as well as the possibilities of its emergence on other planets. A new discovery suggests that ribonucleic acid (or RNA) may have spontaneously formed in basalt glass, a material that was abundant on Earth about 4.35 billion years ago, and is also found on Mars.

Which comes first, DNA or protein? This recurring paradox also applies to the beginning of life on Earth. An alternative hypothesis, proposed 60 years ago and dubbed “The RNA World hypothesis”, suggests that RNA is the origin of living things. This acid is the link between DNA and protein production in our cells: RNA nucleotides transcribed from DNA are used to make proteins.

However, many scientists consider the structure of RNA to be more complex to emerge immediately. They therefore believe that in order to be valid, the “RNA first” model must require at least one experimental demonstration of the formation of RNA molecules long enough to support Darwinian evolution (between 50 and 5000). nucleotide).

Volcanic basalt glass converts triphosphates to RNA

The Hadean period (the first eon of Earth’s history) about 4.35 billion years ago meant that the process took place without human intervention. In addition, basaltic volcanic glass being so present at the time, the material is likely to be largely involved in RNA formation. ” Within a few hundred million years after the formation of the Moon, constant effects combined with abundant volcanism on the young planet formed molten basalt lava, the source of basalt glass. said Stephen Mojzsis, one of the researchers in the new study. ” The effects also evaporate water into dry land, providing aquifers where RNA can be formed. “.

The production of RNA (or polyribonucleic acid) requires ribonucleoside triphosphates. In light of the geological context of the time, the researchers started from the assumption that basalt glass converted ribonucleoside triphosphates into RNA in water. Using gel electrophoresis and ultrafiltration techniques, they showed that this polyribonucleic acid was, on average, 90 to 150 nucleotides in length, and therefore could be the beginning of the Darwinian evolution of life. .

The process of catalytic and polyribonucleic acid synthesis continues over time “, write the authors of the study. In addition, the process takes place under conditions where the RNA is strong (at 25 ° C, pH 7.5). The kinetic data suggest that a small region of the Hadean effect containing only a few metric tons of broken, water-permeable glass may have the capacity to produce nearly one gram of RNA per day, but is limited by the supply of triphosphates.

Frequent effects during Earth formation can also lead to nickel, which has been shown by the group to produce nucleoside triphosphate from nucleosides and activated phosphate, which is also found in volcanic glass. Also extracted from basalt, borate controls the formation of these triphosphates in a pathway for the production of primary RNAs from simple organic molecules.

Similar minerals on Mars, useful in the search for life

These results suggest that polyribonucleotides are present in Hadean environments, if so are triphosphates. ” Models for the fabrication of parts of these nucleosides and links within them, as well as complete nucleoside triphosphates, are currently being developed in many laboratories. “, the researchers will explain.” If triphosphates were present, the glasses on the surface of Hadean Earth (and on Mars) could provide a missing piece of the puzzle of the ‘RNA first’ model. “.

In fact, the same kind of minerals, glass, and impacts are also present on Mars, even if the red planet has not undergone continental drift and plate tectonics – which is why most of Earth’s rocks have disappeared, more than 4 billion years ago. New missions to Mars have found all the rocks necessary for life that could possibly arise in this same simple path, including borate.

Source: Astrobiology

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