Scientists Reproduce a Building Block of Life in Laboratory

Scientists Reproduce a Building Block of Life in Laboratory

“We have demonstrated for the first time that we can make uracil, a component of RNA, non-biologically in a laboratory under conditions found in space,” said Michel Nuevo, research scientist at NASA’s Ames Research Center, Moffett Field, Calif. “We are showing that these laboratory processes, which simulate occurrences in outer space, can make a fundamental building block used by living organisms on Earth.”
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“Nobody really understands how life got started on Earth. Our experiments demonstrate that once the Earth formed, many of the building blocks of life were likely present from the beginning. Since we are simulating universal astrophysical conditions, the same is likely wherever planets are formed,” explained Sandford.

How life evolved: 10 steps to the first cells

How life evolved: 10 steps to the first cells – 14 October 2009 – New Scientist

We may never be able to prove beyond any doubt how life first evolved. But of the many explanations proposed, one stands out – the idea that life evolved in hydrothermal vents deep under the sea. Not in the superhot black smokersMovie Camera, but more placid affairs known as alkaline hydrothermal vents.

This theory can explain life’s strangest feature, and there is growing evidence to support it.

Earlier this year, for instance, lab experiments confirmed that conditions in some of the numerous pores within the vents can lead to high concentrations of large molecules. This makes the vents an ideal setting for the “RNA world” widely thought to have preceded the first cells.

If life did evolve in alkaline hydrothermal vents, it might have happened something like this:
1.

Water percolated down into newly formed rock under the seafloor, where it reacted with minerals such as olivine, producing a warm alkaline fluid rich in hydrogen, sulphides and other chemicals – a process called serpentinisation.

This hot fluid welled up at alkaline hydrothermal vents like those at the Lost City, a vent system discovered near the Mid-Atlantic Ridge in 2000.
2.

Unlike today’s seas, the early ocean was acidic and rich in dissolved iron. When upwelling hydrothermal fluids reacted with this primordial seawater, they produced carbonate rocks riddled with tiny pores and a “foam” of iron-sulphur bubbles.
3.

Inside the iron-sulphur bubbles, hydrogen reacted with carbon dioxide, forming simple organic molecules such as methane, formate and acetate. Some of these reactions were catalysed by the iron-sulphur minerals. Similar iron-sulphur catalysts are still found at the heart of many proteins today.
4.

The electrochemical gradient between the alkaline vent fluid and the acidic seawater leads to the spontaneous formation of acetyl phosphate and pyrophospate, which act just like adenosine triphosphate or ATP, the chemical that powers living cells.

These molecules drove the formation of amino acids – the building blocks of proteins – and nucleotides, the building blocks for RNA and DNA.
5.

Thermal currents and diffusion within the vent pores concentrated larger molecules like nucleotides, driving the formation of RNA and DNA – and providing an ideal setting for their evolution into the world of DNA and proteins. Evolution got under way, with sets of molecules capable of producing more of themselves starting to dominate.
6.

Fatty molecules coated the iron-sulphur froth and spontaneously formed cell-like bubbles. Some of these bubbles would have enclosed self-replicating sets of molecules – the first organic cells. The earliest protocells may have been elusive entities, though, often dissolving and reforming as they circulated within the vents.
7.

The evolution of an enzyme called pyrophosphatase, which catalyses the production of pyrophosphate, allowed the protocells to extract more energy from the gradient between the alkaline vent fluid and the acidic ocean. This ancient enzyme is still found in many bacteria and archaea, the first two branches on the tree of life.
8.

Some protocells started using ATP as well as acetyl phosphate and pyrophosphate. The production of ATP using energy from the electrochemical gradient is perfected with the evolution of the enzyme ATP synthase, found within all life today.
9.

Protocells further from the main vent axis, where the natural electrochemical gradient is weaker, started to generate their own gradient by pumping protons across their membranes, using the energy released when carbon dioxide reacts with hydrogen.

This reaction yields only a small amount of energy, not enough to make ATP. By repeating the reaction and storing the energy in the form of an electrochemical gradient, however, protocells “saved up” enough energy for ATP production.
10.

Once protocells could generate their own electrochemical gradient, they were no longer tied to the vents. Cells left the vents on two separate occasions, with one exodus giving rise to bacteria and the other to archaea.

Was our oldest ancestor a proton-powered rock?

Was our oldest ancestor a proton-powered rock? – life – 19 October 2009 – New Scientist

The picture painted by Russell and Martin is striking indeed. The last common ancestor of all life was not a free-living cell at all, but a porous rock riddled with bubbly iron-sulphur membranes that catalysed primordial biochemical reactions. Powered by hydrogen and proton gradients, this natural flow reactor filled up with organic chemicals, giving rise to proto-life that eventually broke out as the first living cells – not once but twice, giving rise to the bacteria and the archaea.

Many details have yet to be filled in, and it may never be possible to prove beyond any doubt that life evolved by this mechanism. The evidence, however, is growing. This scenario matches the known properties of all life on Earth, is energetically plausible – and returns Mitchell’s great theory to its rightful place at the very centre of biology.

Darwinopterus: New flying dinosaur discovered that could fill evolutionary gap

Darwinopterus: New flying dinosaur discovered that could fill evolutionary gap | Mail Online

The discovery is believed to fill the evolutionary gap between two types of pterosaurs – primitive long-tailed forms and their descendants, advanced short-tailed pterosaurs, some of which reached gigantic size.

The researchers said the groups were separated by a large evolutionary gap, identified in Charles Darwin’s time, which looked as if it would never be filled – until now.

Ribosome Unraveled: A Q&A with Nobelist Thomas Steit

Ribosome Unraveled: A Q&A with Nobelist Thomas Steitz: Scientific American

What we found was this catalysis is done entirely by RNA, which is consistent with the hypothesis that the original ribosome was all RNA, which makes sense if you realize the-chicken-and-the-egg nature of the problem. You can’t make proteins starting with a protein if the first protein is the enzyme that does it, so instead you use RNA.

Ardi: Oldest Human Skeleton Discovered, Bipedalism Origin May Be Revealed

Ardi: Oldest Human Skeleton Discovered, Bipedalism Origin May Be Revealed

Let’s suppose that some lesser male, with poor little stubby canines, figures out that he can entice a fertile female into mating by bringing her some food. That sometimes happens among living chimpanzees, for instance when a female rewards a male for presenting her with a tasty gift of colobus monkey.

Among Ardipithecus’s ancestors, such a strategy could catch on if searching for food required a lot of time and exposure to predators. Males would be far more successful food-providers if they had their hands free to carry home loads of fruits and tubers–which would favor walking on two legs. Females would come to prefer good, steady providers with smaller canines over the big fierce-toothed ones who left as soon as they spot another fertile female. The results, says Lovejoy, are visible in Ardipithecus, which had small canines even in males and walked upright.

Ardi fossil shows ‘apes descended from humans’

TG Daily – Ardi fossil shows ‘apes descended from humans’

A university professor at Kent State University said today that apes, in many ways, evolved from humans, and not the other way round.

Dr C. Owen Lovejoy, a biological anthropologist specializing in the study of human origins, said: “It has been a popular idea to think humans are modified chimpanzees. From studying Ardipithecus ramidus, or ‘Ardi’ we learn that we cannot understand or model human evolution from chimps and gorillas.”

Feathered fossils prove birds evolved from dinosaurs, say Chinese scientists

Feathered fossils prove birds evolved from dinosaurs, say Chinese scientists | Mail Online

The theory that birds evolved from dinosaurs has always been troubled by the absence of feathers more ancient than those on the famous archaeopteryx.

Addressing the annual meeting of the Society of Vertebrate Paleontologists (SVP) in Bristol, Dr Xu Xing, one of the lead scientists behind the discovery, said: ‘These exceptional fossils provide us with evidence that has been missing until now. Now it all fits neatly into place and we have tied up some of the loose ends.’

Five essential things to know about evolution

Five essential things to know about evolution – Ars Technica

If the public doesn’t get evolution, part of the reason may be because many don’t fully appreciate some of the ideas behind the theory. Here’s a rundown of five things about evolution that many people don’t fully understand.

Snake with foot found in China

Snake with foot found in China – Telegraph

Dean Qiongxiu, 66, said she discovered the reptile clinging to the wall of her bedroom with its talons in the middle of the night.

“I woke up and heard a strange scratching sound. I turned on the light and saw this monster working its way along the wall using his claw,” said Mrs Duan of Suining, southwest China.