Missing link of life may not be a fossil, but a droplet

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Writing of the Technological Innovation Site – 10/05/2021

Missing link of life can not

Droplets that had protogenic elements “lived” longer and replicated.
[Imagem: Muneyuki Matsuo et al. – 10.1038/s41467-021-25530-6]

missing link

The “missing link” that marks the emergence of life, after all, may not be the much-discussed fossil of the primordial organism.

Instead, two Japanese researchers are proposing that the leap from “non-life” to life – or from chemistry to biology – may have been the responsibility of a tiny self-replicating globule called coacervate gout.

Coacervate is a viscous liquid phase rich in colloids that can be separated from a colloidal solution by the addition of a third component.

“Chemical evolution was first proposed in the 1920s as the idea that life first originated with the formation of macromolecules from small simple molecules, and these macromolecules formed molecular clusters that could proliferate. Since then, many studies have been carried out. were carried out to experimentally verify the hypothesis of the RNA world – where only self-replicating genetic material existed, before the evolution of DNA and proteins,” says Professor Muneyuki Matsuo, from the University of Hiroshima.

However, none of these experiments were successful, and this missing link between chemistry and biology at the origin of life has remained a mystery for more than a hundred years.

Evolving world of droplets

The question that remains unanswered, therefore, is: How did chemical compounds released on the early Earth come to life?

Trying to answer this question, Matsuo and his colleague Kensuke Kurihara initially thought that it was about the environment: Ingredients would have formed under high pressure and temperature, and then cooled under conditions more favorable to life. The problem was propagation.

“Proliferation requires spontaneous polymer production and self-assembly under the same conditions,” explained Matsuo.

The two researchers then used amino acid derivatives as precursors to a new prebiotic monomer, which could be the building block for self-assembly of primitive cells. When added to water at room temperature and under atmospheric pressure, the amino acid derivatives condensed, organizing into peptides, which then spontaneously formed droplets.

Surprisingly, the drops increased in size and number when fed more amino acids. Furthermore, the droplets sometimes concentrated nucleic acids – genetic material – and were more likely to survive external stimuli when they developed this function.

“A droplet-based protocell may have served as a link between chemistry and biology during the origins of life,” proposes Matsuo. “This study may serve to explain the emergence of the first living organisms on primordial Earth.”

Missing link of life can not

The next step is to demonstrate continuous evolution.
[Imagem: Muneyuki Matsuo et al. – 10.1038/s41467-021-25530-6]

Protovida

The two researchers plan to continue investigating the evolution process of amino acid derivatives, to see if they reach primitive living cells.

“By building peptide droplets that proliferate by feeding on new amino acid derivatives, we experimentally elucidate the long-standing mystery of how prebiotic ancestors were able to proliferate and survive by selectively concentrating prebiotic chemicals,” said Matsuo. “Instead of an RNA world, we found that a ‘droplet world’ may be a more accurate description, as our results suggest that the droplets have become molecular aggregates capable of evolving – one of which became our common ancestor. “

The duo plans to improve their platform to try to demonstrate the continued evolution of their drops and, ultimately, the emergence of some form of “protolife.”

Bibliography:

Article: Proliferating coacervate droplets as the missing link between chemistry and biology in the origins of life
Authors: Muneyuki Matsuo, Kensuke Kurihara
Magazine: Nature Communications
Vol.: 12, 5487
DOI: 10.1038/s41467-021-25530-6

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