Chaotic flows and the origin of life

A research team at Texas A&M University has uncovered a physical mechanism that may help answer one of the major questions concerning the origin of life, "How did the building blocks form?"

Chaotic advection accelerates interfacial transport under hydrothermally relevant conditions 
[Credit: Proceedings of the National Academy of Sciences]

The research team is led by Dr. Victor Ugaz, professor and holder of the Charles D. Holland '53 Professorship and the Thaman Professorship in the Artie McFerrin Department of Chemical Engineering. The team also includes Dr. Yassin A. Hassan, professor and holder of the Sallie & Don Davis '61 Professorship and department head of the Department of Nuclear Engineering.

Scientists have long known that the building blocks of life – amino acids, nucleobases and sugars – were present in the early ocean, but they were very low in concentration. In order for life to emerge, these building blocks needed to be combined and enriched into long-chain macromolecules. Identifying the process and mechanism driving this synthesis has been one of the largest questions concerning the origin of life.

"In the early ocean, those building blocks were present in the environment," Ugaz said. "They were there, but they were so dilute; there is a question about how they combined. So one area of interest is what kind of concentration mechanism could have existed to enrich those components to a point where they could start to form longer chains, more complex molecules."

In an article appearing in Proceedings of the National Academy of Sciences, the Texas A&M research team describes a mechanism that may have played a major role in combining these dilute chemical building blocks into the long-chain macromolecules necessary for life.

The research team explored this by creating a model system of cylindrical cells that mimic the structure of pores in mineral formations found near a recently discovered, new type of subsea hydrothermal vent. The temperature gradients present within these vents function just like an ordinary lava lamp, circulating fluid within the tiny pore spaces. The team found that these flows are surprisingly complex and chaotic – meaning that individual paths follow a rough general pattern, but no trajectories are identical. This discovery made it possible to identify conditions where these flows are able to provide bulk homogenization of the various organic molecules present in the vents, while at the same time transport them to catalytically active pore surfaces where they absorb and react.

According to Ugaz, there is an easy way to picture this phenomenon. "Imagine you are stirring coffee, and you put in some cream or something that would stick to the side of the cup. When you stir it a certain way, two things are actually happening at once: you are mixing the bulk of the liquid, but you are also making it go to a certain spot on the surface of the cup."

These flows naturally occur within hydrothermal pore networks providing an intriguing mechanism to explain how dilute organic precursors in the early ocean could have assembled into complex biomacromolecules. This has been one of the key unanswered questions in the origin of life on Earth, and in extraterrestrial systems where similar hydrothermal environments have been discovered. Beyond this finding, the research is significant in a number of other ways.

There are a whole host of different processes beyond the biotic and prebiotic chemistry that can be catalyzed in these environments. First, these porous formations play a major role in converting carbon dioxide into various carbonates. The exact mechanisms driving this carbon dioxide capture are not currently well described. However, the results of this study indicate that these chaotic flows may be able to help describe this phenomenon.

Further, with a better understanding of these flows and how they drive reactions at a surface, it is feasible that they could drive a new type of reactor. As the flows rely on heat differences, such a reactor could be entirely passive, utilizing waste heat to drive reactions.

Author: Drew Thompson | Source: Artie McFerrin Department of Chemical Engineering at Texas A&M University [April 14, 2017]

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in Biology, Earth Science, Evolution, Oceans, Origin of Life

April 13, 2017

Chaotic flows and the origin of life

A research team at Texas A&M University has uncovered a physical mechanism that may help answer one of the major questions concerning th...

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How life may have begun in space

What chemical processes in space could have created the building blocks of life is being researched by chemists at Ruhr-Universität Bochum (RUB) in Prof Dr Wolfram Sander's team. In their experiments, the scientists are simulating the conditions in space to understand in detail how certain chemical reactions occur.

How the building blocks of life came to Earth is an unsolved puzzle. Maybe comets had something to do with it 
[Credit: NASA/JPL-Caltech]

One theory says that the building blocks of life were not created on Earth. Cometary impacts may have brought amino acids, the basic units of proteins, to our planet. How such complex molecules could have formed in space is a question being investigated by Sander's team. The scientists are interested in processes in a condensed phase, i.e. in liquids, solids or on surfaces, into which there has been little research.

A precursor of amino acids

Besides hydrogen and oxygen, the icy core of comets usually also contains nitrogen and carbon -- all the elements needed for an amino acid. A possible precursor of amino acids in space could be the molecule hydroxylamine (NH2-OH), which consists of one nitrogen, one oxygen and three hydrogen atoms. However, it has not yet been possible to verify this in space.

RUB PhD student Yetsedaw Tsegaw investigated in an experiment whether the conditions in space would actually allow this molecule to form. He adjusted the conditions in the comet ice in the lab, brought ammonia (NH3) and oxygen (O2) together in this environment and treated the mixture with high-energy radiation, such as that found in space. He observed the reactions that occurred with a special form of infrared spectroscopy.

Hidden molecule

Tsegaw took the measurements as a guest researcher in the working group of Prof Dr Ralf Kaiser at "WM Keck Research Laboratory in Astrochemistry" in Hawaii. He then analysed the data at RUB. The result: hydroxylamine was actually created in the experiment. However, it was not visible at first sight. The bands of hydroxylamine were overlaid in the infrared spectrum by the bands of other molecules. Only when Tsegaw gradually warmed the sample and the interfering substances evaporated was he able to identify hydroxylamine.

In theory, the molecule could thus form in comet ice. The chemist presumes that people had not been searching for it using the right methods until now.

You can find more information in a detailed article in the science magazine Rubin at Ruhr-Universität Bochum.

Source: Ruhr-Universitaet-Bochum [April 10, 2017]

byUnknown

in Astrobiology, Astronomy, Origin of Life, Universe

April 10, 2017

How life may have begun in space

What chemical processes in space could have created the building blocks of life is being researched by chemists at Ruhr-Universität Bochum (...

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Experiments test how easy life itself might be

On a lab benchtop, a handful of glass vials taped to a rocker gently sway back and forth. Inside the vials, a mixture of organic chemicals and tiny particles of fool's gold are begging a question seemingly beyond their humble appearance: Where did life come from?

UW scientists are combining theory with experiment to try to understand how life could arise from lifelike chemical 
reactions under the right conditions. “If we find many different chemistries supporting lifelike reactions, we can 
expect more origins of life elsewhere in the universe,” says botany Professor David Baum 
[Credit: Jeff Miller]

Combining theory with experiment, University of Wisconsin–Madison scientists are trying to understand how life can arise from non-life. Researchers at the UW–Madison Wisconsin Institute for Discovery are conducting experiments to test the idea that lifelike chemical reactions might develop readily under the right conditions. The work addresses some of the deepest mysteries in biology, and has implications for understanding how common life might be in the universe.

David Baum, chair and professor of botany at UW–Madison and a Discovery Fellow at WID, thinks the earliest life might have relied on a primitive metabolism that originally started on mineral surfaces. Many central reactions in modern cells rely on iron-sulfur catalysts. This reliance on iron and sulfur could be a record stamped into cells of the environments where metabolism itself first evolved. Baum is testing this idea by turning to iron pyrite, a mineral of iron and sulfur better known as fool's gold.

Together with Mike Berg, a graduate student researching the origins of life, Baum is mixing microscopic beads of iron pyrite with a source of chemical energy and simple molecular building blocks. As vials of this mixture rock back and forth in the lab, small groups of chemicals bound to the mineral surface might aggregate and start assisting one another in producing more chemicals. If so, they're likely to spread to other iron pyrite beads, colonizing new surfaces.

When Berg transfers some beads to a fresh vial, the chemical groups could continue to spread. Generation after generation, vial after vial, the most efficient and competitive chemical mixtures would colonize the most iron pyrite. This is selection. Like natural selection, which has created the diversity and complexity of life on Earth, selecting for the colonizing ability of these chemical groups may reveal lifelike chemical cycles capable of changing over time.

"The view that I've come around to is that lifelike chemistry may pop up relatively easily in many, many geological settings," says Baum. "The problem then changes. It's no longer a problem of 'will it happen,' but how will we know it happened?"

Vials containing a mixture of simple organic chemicals and microscopic beads of fool’s gold are taped
 to a rocker in the Baum lab at the UW–Madison Wisconsin Institute for Discovery 
[Credit: University of Wisconsin-Madison]

They've gone through more than 30 generations so far, and are looking for any sign of change over time, whether that is heat generation, energy consumption or the amount of material bound to the beads.

Baum and UW–Madison microbiologist and WID systems biologist Kalin Vetsigian published a paper last year that outlined the experiments, which are based in part on the principle of neighborhood selection. Normally, natural selection operates on a population of individuals. But the scientists proposed that even though no well-defined individuals exist in the chemical mixtures, the molecular communities that are best at colonizing new surfaces will prevail, and likely get better over time. Successful traits of the community as a whole can be selected for and passed on.

"This community-level selection could have taken place before there were individuals with traits that were both heritable and variable," says Vetsigian. "If you have good communities, they will persist."

The project recently received $2.5 million in funding from NASA. Baum is the lead investigator of the research, which includes Vetsigian, UW–Madison chemist Tehshik Yoon, and collaborators from seven other institutions.

Cells need the kinds of metabolic reactions that Baum studies to produce energy and the components of more complex molecules. They also need a way to store information. All living cells pass on their genetic information with DNA. But UW–Madison professor of chemical and biological engineering and WID systems biologist John Yin is exploring alternative ways to store and process information with simpler molecules in an effort to understand how information storage could evolve without cells or DNA.

Taking a cue from computer science, Yin is working with the most basic method of encoding information, binary. In place of electronic bits, his ones and zeros are the two simplest amino acids, glycine and alanine. Using a unique form of chemistry, Yin is drying out mixtures of the amino acids to encourage them to join together.

"We're seeing reproducibly different strings of alanine and glycine under different kinds of conditions," explains Yin. "So that's a first hint that in some ways the product is a way of representing a particular environment."

Yin's group is working on the technically challenging task of reading these sequences of amino acids so they can keep track of the molecular information. The Yin lab eventually hopes to discover groups of chemicals that can build off this molecular information to reproduce themselves. For both Baum and Yin, selectable systems require these cycles of chemicals able to make more of one another, what Yin calls "closing the loop."

Closing the loop in the lab is likely to be difficult. Only experimentation will tell for sure.

Yin, Baum and Vetsigian are interested not only in how life on Earth got started, but how it could get started—anywhere. If lifelike chemical reactions and molecular information are readily produced in the lab, that could change the calculus of how common life might be on other worlds.

"If we find many different chemistries supporting lifelike reactions, we can expect more origins of life elsewhere in the universe," says Baum.

Author: Eric Hamilton | Source: University of Wisconsin-Madison [April 06, 2017]

byUnknown

in Evolution, Genetics, Origin of Life

April 06, 2017

Experiments test how easy life itself might be

On a lab benchtop, a handful of glass vials taped to a rocker gently sway back and forth. Inside the vials, a mixture of organic chemicals a...

Read More