Volcanoes ignited the spark of life | illvet.se

Researchers at the Foundation for Applied Molecular Evolution in the US have mixed a mixture of organic molecules to mimic the first steps in the origin of life. Other researchers have done this before.

What’s new, though, is that American researchers added an extra ingredient, which almost magically made the difference.

The new component is something called basaltic glass, which forms when lava cools rapidly, for example when it meets water. When glass was added, long strands of RNA were produced, which, according to the prevailing theory, formed the backbone of early life.

RNA performs all functions

Today, all life forms depend on the DNA molecule, which contains the genetic information of cells. DNA, which is shaped like a twisted double strand, contains rows of four different building blocks, called nucleotides, each carrying a base.

Nucleotides are also called letters of the genetic alphabet, because they form different codes, in the same way that the order of letters can form different words.

RNA also contains nucleotides, but unlike DNA, it consists of only one strand.

RNA plays a critical role in the functioning of cells, transmitting genetic information from DNA to the cell’s protein factories, the ribosomes. Based on the genetic recipe in RNA, ribosomes make proteins that perform important functions in cells.

However, RNA is more than just a messenger. RNA strands can fold in special ways, so they have other functions and, among other things, they can produce proteins and make copies of themselves.

RNA’s ability to carry out many of life’s central processes paved the way for the idea that it was the original engine of the first primitive life forms.

This idea is called the RNA world hypothesis. The point of the RNA world hypothesis is that RNA was responsible for everything DNA and proteins do in modern forms of life. Thus, only one “invention”, RNA, was needed to start life.

However, the weakness of the RNA world hypothesis is that it does not explain how the first RNA molecule came to be. Therefore, researchers have long been looking for environments in which spontaneous formation of RNA can occur – which has led to several very different ideas.

A new look at the cradle of life

Some researchers He thinks that the first RNA originated in small lakes that alternately drained and filled with water. The idea is that the constant changes promoted the formation of RNA strands.

Another idea is that the planet’s first RNA molecule was formed in hot springs in the ocean depths. In such sources are chimney-like mineral-rich structures that may have sequestered and concentrated the organic molecules that make up RNA. simulation showed that this could lead to the formation of RNA, but only from very short strands.

The third theory is that ice crystals may have promoted the formation of RNA strands. It is an Rna that is more stable at lower temperatures, and attempt They show that RNA is better at solving tasks for proteins in environments below freezing point. However, it is very unlikely that there was ice on the planet when the RNA molecules arose.

The new theory, in which basalt glass plays a major role, is more consistent with the conditions that prevailed on Earth at the time of the emergence of life about four billion years ago.

Violent volcanic eruptions across the planet contributed to an abundance of basaltic glass, which may have been the critical factor in the formation of RNA strands. Glass, which facilitated chemical reactions without being part of them, thus acts as a catalyst.

American researchers led by molecular biologist Elisa Biondi have come up with a different series an experience With samples of four types of glass, including basalt glass. Samples were crushed and sterilized before being sprayed into an aqueous solution of the four building blocks of RNA.

The mixtures were then allowed to stand for up to eight months. Meanwhile, the researchers took small samples and analyzed the contents.

The analyzes showed that in the samples with basalt glass there were large RNA molecules with up to 200 nucleotides, while in the other samples there were no RNA molecules at all.

“We wanted to investigate the possibility of nucleotide assembly, but finding such large RNA molecules was completely unexpected. We were surprised and delighted, ”says Biondi.

In fact, the results were so extraordinary that the researchers didn’t dare believe them. Therefore, they repeated the experiments several times and left the mixtures for a longer and longer period of time. However, there was no doubt about it: the mixture of nucleotides and basalt glass gave rise to large RNA molecules.

The experiment thus shows how the first complex RNA molecules can arise spontaneously.

Meteorites planted the seeds of life

The next question then is where the building blocks of rna and their associated nucleotides and bases come from.

It may have formed here on Earth, but it is much more likely that it was formed in space. In meteorites, scientists is found All four bases are in RNA, so the building blocks of life probably came from outside.

Although researchers now have a possible explanation for how the RNA world came to be, they can’t be sure that this is really how it happened.

“Our results are strong evidence for the existence of an RNA world. We may not be able to describe exactly how life arose, but we can map the principles behind this process,” says Elisa Biondi.

Here on Earth, the basaltic glass that was at the origin of life is long gone. Tectonic forces are constantly pulling material from the earth’s surface deeper into the earth, so any trace of the rna world is lost forever.

Therefore, we may need to turn our eyes to our neighbor in the solar system to see how the dead building blocks of the first life came together. Unlike Earth, Mars has no plate tectonics, so ancient basaltic glass remains on the surface.

Four million years ago, Mars had a much warmer climate, active volcanoes and water on its surface, and like Earth, the planet was frequently hit by meteorites.

Thus, life could in principle have originated on Mars. Perhaps this is where we find the answer to how life arose on our planet.