The current study provides strong evidence that this crucial step for the emergence of life can indeed occur even in the very inhospitable conditions of space.
The origin of life is one of the great questions of mankind. One of the prerequisites for the emergence of life is the abiotic—not by living beings caused chemical—production and polymerization of amino acids, the building blocks of life.
"Two scenarios are being discussed for the emergence of life on Earth: On the one hand, the first-time creation of such amino acid chains on Earth, and on the other hand, the influx from space," explains Tilmann Märk from the Department of Ion Physics and Applied Physics. of the University of Innsbruck. "For the latter, such amino acid chains would have to be generated in the very unfavorable and inhospitable conditions in space."
A team of researchers led by Michel Farizon from the University of Lyon and Tilmann Märk has now made a significant discovery in the field of abiotic peptide chain formation from amino acids for the smallest occurring amino acid, glycine, a molecule that has been observed several times extraterrestrially in recent years.
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Scientists announce a breakthrough in determining life's origin on Earth—and maybe Mars
Scientists at the Foundation for Applied Molecular Evolution announced today that ribonucleic acid (RNA), an analog of DNA that was likely the first genetic material for life, spontaneously forms on basalt lava glass. Such glass was abundant on Earth 4.35 billion years ago. Similar basalts of this antiquity survive on Mars today.
"Communities studying the origins of life have diverged in recent years," remarked Steven Benner, a co-author of the study appearing online in the journal Astrobiology.
"One community re-visits classical questions with complex chemical schemes that require difficult chemistry performed by skilled chemists," Benner explained. "Their beautiful craftwork appears in brand-name journals such as Nature and Science." However, precisely because of the complexity of this chemistry, it cannot possibly account for how life actually originated on Earth.
"If life emerged on Earth via this simple path, then it also likely emerged on Mars,"
In contrast, the Foundation study takes a simpler approach. Led by Elisa Biondi, the study shows that long RNA molecules, 100-200 nucleotides in length, form when nucleoside triphosphates do nothing more than percolate through basaltic glass.
"Basaltic glass was everywhere on Earth at the time," remarked Stephen Mojzsis, an Earth scientist who also participated in the study. "For several hundred million years after the Moon formed, frequent impacts coupled with abundant volcanism on the young planet formed molten basaltic lava, the source of the basalt glass. Impacts also evaporated water to give dry land, providing aquifers where RNA could have formed."
The same impacts also delivered nickel, which the team showed gives nucleoside triphosphates from nucleosides and activated phosphate, also found in lava glass. Borate (as in borax), also from the basalt, controls the formation of those triphosphates.
The beauty of this model is its simplicity. It can be tested by highschoolers in chemistry class
The same impactors that formed the glass also transiently reduced the atmosphere with their metal iron-nickel cores. RNA bases, whose sequences store genetic information, are formed in such atmospheres. The team had previously 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 highschoolers in chemistry class," said Jan Špaček, who was not involved in this study but who develops instrument to detect alien genetic polymers on Mars. "Mix the ingredients, wait for a few days and detect the RNA."
The same rocks resolve the other paradoxes in making RNA in a path that moves all of the way from simple organic molecules to the first RNA. "For example, borate manages the formation of ribose, the 'R' in RNA," Benner added. This path starts from simple carbohydrates that could "not not" have formed in the atmosphere above primitive Earth. These were stabilized by volcanic sulfur dioxide, and then rained to the surface to create reservoirs of organic minerals.
Thus, this work completes a path that creates RNA from small organic molecules that were almost certainly present on the early Earth. A single geological model moves from one and two carbon molecules to give RNA molecules long enough to support Darwinian evolution.
"Important questions remain," cautions Benner. "We still do not know how all of the RNA building blocks came to have the same general shape, a relationship known as homochirality." Likewise, the linkages between the nucleotides can be variable in the material synthesized on basaltic glass. The import of this is not known.
Mars is relevant to this announcement because the same minerals, glasses, and impacts were also present on Mars of that antiquity. However, Mars has not suffered continental drift and plate tectonics that buried most rocks from 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 of the needed rocks, including borate.
"If life emerged on Earth via this simple path, then it also likely emerged on Mars," said Benner. "This makes it even more important to seek life on Mars as soon as we can."
https://phys.org/news/2022-06-scientists-breakthrough-life-earthand-mars.html
More detailed information can be found here, here and here.
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When I was a kid, we moved into a house that had a huge lilac tree out front. It was mostly rotten, and it needed to be taken down before it fell. It took a while, but eventually, it was gone.
Mostly. A couple years later, little lilac babies popped out of the ground in its place. My mom was determined to get rid of them, because she'd planted a beautiful flower garden there, and the lilac trees would overshadow and kill the whole garden. I insisted on saving at least a few saplings. She said fine, but I had to dig them out and put them in pots myself.
So, I did. I spent days digging little lilac bushes out of the ground and putting them into pots. Some couldn't be saved, but some could. When all was said and done, I had five brand-new lilac saplings. Seven or eight years old, and it was my absolute pride and joy.
Three died due to sun scorching, severe drought that no amount of watering could save, and perhaps just being moved from their place in the ground. But two survived, and I was awfully proud of them! I'd go out and talk to them every single day. I watered them by hand and made sure they were fertilized properly. I learned all about their favored environments, and I was determined to make sure they lived.
One of my mom's friends saw what I was doing with the lilacs. She asked if she could have one to put in her backyard, and I agreed on the condition that she take very, very good care of it.
It's now fucking enormous. I'm talking ten feet tall and bursting with beautiful purple flowers every spring. My mom still gets updates each year as they start to bloom, which she forwards to me. And all I can think is, "That's my friend! Thriving some twenty years on, there it is."
The other tree nearly died, too. It lived in a pot for far, far too long. I wanted to plant it somewhere in my parents' yard, but my mom was reluctant. Eventually, we agreed to put it in the far back garden. It grew okay for many years, despite the shade, but in all these years, it's never bloomed.
Last year, the massive tree casting massive shadows over the lilac and the garden cracked in half and fell. It tumbled into the garden, crushing part of the nearby shed and destroying a few plants beneath it.
It missed my lilac by inches.
The clean-up is long done. The rest of the tree has been cut down, and my lilac has full sunlight for the first time in fifteen years. It won't bloom this year, I know. But it's got new shoots up. It's taller than ever. I spent half an hour a few weeks ago praising it for surviving all this time, dreaming about its future and telling it how I believe it'll become the tall beauty it's always been meant to be.
I think next year, I'll see flowers.
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