Researchers create artificial cells that act like living cells

In a new study published in Nature Chemistry, UNC-Chapel Hill researcher Ronit Freeman and her colleagues describe the steps they took to manipulate DNA and proteins -- essential building blocks of life -- to create cells that look and act like cells from the body. This accomplishment, a first in the field, has implications for efforts in regenerative medicine, drug delivery systems, and diagnostic tools.

"With this discovery, we can think of engineering fabrics or tissues that can be sensitive to changes in their environment and behave in dynamic ways," says Freeman, whose lab is in the Applied Physical Sciences Department of the UNC College of Arts and Sciences.

Cells and tissues are made of proteins that come together to perform tasks and make structures. Proteins are essential for forming the framework of a cell, called the cytoskeleton. Without it, cells wouldn't be able to function. The cytoskeleton allows cells to be flexible, both in shape and in response to their environment.

Without using natural proteins, the Freeman Lab built cells with functional cytoskeletons that can change shape and react to their surroundings. To do this, they used a new programmable peptide-DNA technology that directs peptides, the building blocks of proteins, and repurposed genetic material to work together to form a cytoskeleton.

"DNA does not normally appear in a cytoskeleton," Freeman says. "We reprogrammed sequences of DNA so that it acts as an architectural material, binding the peptides together. Once this programmed material was placed in a droplet of water, the structures took shape."

The ability to program DNA in this way means scientists can create cells to serve specific functions and even fine-tune a cell's response to external stressors. While living cells are more complex than the synthetic ones created by the Freeman Lab, they are also more unpredictable and more susceptible to hostile environments, like severe temperatures.

"The synthetic cells were stable even at 122 degrees Fahrenheit, opening up the possibility of manufacturing cells with extraordinary capabilities in environments normally unsuitable to human life," Freeman says.

Instead of creating materials that are made to last, Freeman says their materials are made to task -- perform a specific function and then modify themselves to serve a new function. Their application can be customized by adding different peptide or DNA designs to program cells in materials like fabrics or tissues. These new materials can integrate with other synthetic cell technologies, all with potential applications that could revolutionize fields like biotechnology and medicine.

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Researchers develop artificial building blocks of life

The DNA carries the genetic information of all living organisms and consists of only four different building blocks, the nucleotides. Nucleotides are composed of three distinctive parts: a sugar molecule, a phosphate group and one of the four nucleobases adenine, thymine, guanine and cytosine. The nucleotides are lined up millions of times and form the DNA double helix, similar to a spiral staircase. Scientists from the UoC's Department of Chemistry have now shown that the structure of nucleotides can be modified to a great extent in the laboratory.

The researchers developed so-called threofuranosyl nucleic acid (TNA) with a new, additional base pair.

These are the first steps on the way to fully artificial nucleic acids with enhanced chemical functionalities.

The study 'Expanding the Horizon of the Xeno Nucleic Acid Space: Threose Nucleic Acids with Increased Information Storage' was published in the Journal of the American Chemical Society.

Artificial nucleic acids differ in structure from their originals.

These changes affect their stability and function. "Our threofuranosyl nucleic acid is more stable than the naturally occurring nucleic acids DNA and RNA, which brings many advantages for future therapeutic use," said Professor Dr Stephanie Kath-Schorr.

For the study, the 5-carbon sugar deoxyribose, which forms the backbone in DNA, was replaced by a 4-carbon sugar.

In addition, the number of nucleobases was increased from four to six.

By exchanging the sugar, the TNA is not recognized by the cell's own degradation enzymes.

This has been a problem with nucleic acid-based therapeutics, as synthetically produced RNA that is introduced into a cell is rapidly degraded and loses its effect.

The introduction of TNAs into cells that remain undetected could now maintain the effect for longer.

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'Bouncing' comets could deliver building blocks for life to exoplanets

How did the molecular building blocks for life end up on Earth? One long-standing theory is that they could have been delivered by comets. Now, researchers from the University of Cambridge have shown how comets could deposit similar building blocks to other planets in the galaxy.

In order to deliver organic material, comets need to be travelling relatively slowly -- at speeds below 15 kilometres per second. At higher speeds, the essential molecules would not survive -- the speed and temperature of impact would cause them to break apart.

The most likely place where comets can travel at the right speed are 'peas in a pod' systems, where a group of planets orbit closely together. In such a system, the comet could essentially be passed or 'bounced' from the orbit of one planet to another, slowing it down.

At slow enough speeds, the comet would crash on a planet's surface, delivering the intact molecules that researchers believe are the precursors for life. The results, reported in the Proceedings of the Royal Society A, suggest that such systems would be promising places to search for life outside our Solar System if cometary delivery is important for the origins of life.

Comets are known to contain a range of the building blocks for life, known as prebiotic molecules. For example, samples from the Ryugu asteroid, analysed in 2022, showed that it carried intact amino acids and vitamin B3. Comets also contain large amounts of hydrogen cyanide (HCN), another important prebiotic molecule. The strong carbon-nitrogen bonds of HCN make it more durable to high temperatures, meaning it could potentially survive atmospheric entry and remain intact.

"We're learning more about the atmospheres of exoplanets all the time, so we wanted to see if there are planets where complex molecules could also be delivered by comets," said first author Richard Anslow from Cambridge's Institute of Astronomy. "It's possible that the molecules that led to life on Earth came from comets, so the same could be true for planets elsewhere in the galaxy."

The researchers do not claim that comets are necessary to the origin of life on Earth or any other planet, but instead they wanted to place some limits on the types of planets where complex molecules, such as HCN, could be successfully delivered by comets.

Most of the comets in our Solar System sit beyond the orbit of Neptune, in what is known as the Kuiper Belt. When comets or other Kuiper Belt objects (KBOs) collide, they can be pushed by Neptune's gravity toward the Sun, eventually getting pulled in by Jupiter's gravity. Some of these comets make their way past the Asteroid Belt and into the inner Solar System.

"We wanted to test our theories on planets that are similar to our own, as Earth is currently our only example of a planet that supports life," said Anslow. "What kinds of comets, travelling at what kinds of speed, could deliver intact prebiotic molecules?"

Using a variety of mathematical modelling techniques, the researchers determined that it is possible for comets to deliver the precursor molecules for life, but only in certain scenarios. For planets orbiting a star similar to our own Sun, the planet needs to be low mass and it is helpful for the planet to be in close orbit to other planets in the system. The researchers found that nearby planets on close orbits are much more important for planets around lower-mass stars, where the typical speeds are much higher.

In such a system, a comet could be pulled in by the gravitational pull of one planet, then passed to another planet before impact. If this 'comet-passing' happened enough times, the comet would slow down enough so that some prebiotic molecules could survive atmospheric entry.

"In these tightly-packed systems, each planet has a chance to interact with and trap a comet," said Anslow. "It's possible that this mechanism could be how prebiotic molecules end up on planets."

For planets in orbit around lower-mass stars, such as M-dwarfs, it would be more difficult for complex molecules to be delivered by comets, especially if the planets are loosely packed. Rocky planets in these systems also suffer significantly more high-velocity impacts, potentially posing unique challenges for life on these planets.

The researchers say their results could be useful when determining where to look for life outside the Solar System.

"It's exciting that we can start identifying the type of systems we can use to test different origin scenarios," said Anslow. "It's a different way to look at the great work that's already been done on Earth. What molecular pathways led to the enormous variety of life we see around us? Are there other planets where the same pathways exist? It's an exciting time, being able to combine advances in astronomy and chemistry to study some of the most fundamental questions of all."

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Two meteorites are providing a detailed look into outer space

If you've ever seen a shooting star, you might have actually seen a meteor on its way to Earth. Those that land here are called meteorites and can be used to peek back in time, into the far corners of outer space or at the earliest building blocks of life. Today, scientists report some of the most detailed analyses yet of the organic material of two meteorites. They've identified tens of thousands of molecular "puzzle pieces," including a larger amount of oxygen atoms than they had expected.

The researchers will present their results at the spring meeting of the American Chemical Society (ACS).

Previously, the team led by Alan Marshall, Ph.D., investigated complex mixtures of organic materials found on Earth, including petroleum. But now, they are turning their attention toward the skies -- or the things that have fallen from them. Their ultra-high resolution mass spectrometry (MS) technique is starting to reveal new information about the universe and could ultimately provide a window into the origin of life itself.

"This analysis gives us an idea of what's out there, what we're going to run into as we move forward as a 'spacefaring' species," says Joseph Frye-Jones, a graduate student who is presenting the work at the meeting. Both Marshall and Frye-Jones are at Florida State University and the National High Magnetic Field Laboratory.

Thousands of meteorites fall to Earth every year, but only a rare few are "carbonaceous chondrites," the category of space rock that contains the most organic, or carbon-containing, material. One of the most famous is the "Murchison" meteorite, which fell in Australia in 1969 and has been studied extensively since. A newer entry is the relatively unexplored "Aguas Zarcas," which fell in Costa Rica in 2019, bursting through back porches and even a doghouse as its pieces fell to the ground. By understanding the organic makeup of these meteorites, researchers can obtain information about where and when the rocks formed, and what they ran into on their journey through space.

To make sense of the complicated jumble of molecules on the meteorites, the scientists turned to MS. This technique blasts a sample apart into tiny particles, then basically reports the mass of each one, represented as a peak. By analyzing the collection of peaks, or the spectrum, scientists can learn what was in the original sample. But in many cases, the resolution of the spectrum is only good enough to confirm the presence of a compound that was already presumed to be there, rather than providing information about unknown components.

This is where Fourier-transform ion cyclotron resonance (FT-ICR) MS comes in, which is also known as "ultra-high resolution" MS. It can analyze incredibly complex mixtures with very high levels of resolution and accuracy. It's especially well suited for analyzing mixtures, like petroleum, or the complex organic material extracted from a meteorite. "With this instrument, we really have the resolution to look at everything in many kinds of samples," says Frye-Jones.

The researchers extracted the organic material from samples of both the Murchison and Aguas Zarcas meteorites, then analyzed it with ultra-high resolution MS. Rather than analyzing only one specific class of molecules at a time, such as amino acids, they chose to look at all soluble organic material at once. This provided the team with more than 30,000 peaks for each meteorite to analyze, and over 60% of them could be given a unique molecular formula. Frye-Jones says these results represent the first analysis of this type on the Aguas Zarcas meteorite, and the highest-resolution analysis on the Murchison one. In fact, this team identified nearly twice as many molecular formulas as previously reported for the older meteorite.

Once determined, the data were sorted into unique groups based on various characteristics, such as whether they included oxygen or sulfur, or whether they potentially contained a ring structure or double bonds. They were surprised to find a large amount of oxygen content among the compounds. "You don't think of oxygen-containing organics as being a big part of meteorites," explained Marshall.

The researchers will next turn their attention to two far more precious samples: a few grams of lunar dust from the Apollo 12 and 14 missions of 1969 and 1971, respectively. These samples predate Marshall's invention of FT-ICR MS in the early 1970s. Instrumentation has come a long way in the decades since and is now perfectly poised to analyze these powders. The team will soon compare their results from the meteorite analyses to the data they obtain from the lunar samples, hoping to learn more information about where the moon's surface came from. "Was it from meteorites? Solar radiation? We should be able to soon shed some light on that," says Marshall.

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Does ice in the Universe contain the molecules making up the building blocks of life in planetary systems?

The James Webb Space Telescope -- the most precise telescope ever built -- was decisive in discovering the frozen forms of a long series of molecules, such as carbon dioxide, ammonia, methane, methanol and even more complex molecules, frozen out as ices on the surface of small dust grains.

The dust grains grow in size when being a part of the discs of gas and dust forming around young stars. This means that the researchers could study many of the molecules going into the forming of new exoplanets.

Researchers at the Niels Bohr Institute, University of Copenhagen, combined the discoveries from JWST with data from Atacama Large Millimeter Array (ALMA), making observations in other wavelengths than JWST and researchers from Aarhus University contributed with the necessary investigations in the laboratory.

"With the application of observations, e.g. from ALMA, it is possible for us to directly observe the dust grains themselves, and it is also possible to see the same molecules as in the gas observed in the ice" Lars Kristensen, associate Professor at the Niels Bohr Institute (NBI), explains.

"Using the combined data set gives us a unique insight into the complex interactions between gas, ice and dust in areas where stars and planets form" according to Jes Jørgensen, Professor at NBI.

"This way we can map the location of the molecules in the area both before and after they have been frozen out onto the dust grains and we can follow their path from the cold molecular cloud to the emerging planetary systems around young stars."

The content of ice in the molecular cloud was a decisive discovery

The ices were detected and measured by studying how starlight from beyond the molecular cloud was absorbed by icy molecules at specific infrared wavelengths visible to Webb.

This process leaves behind chemical fingerprints known as absorption spectra which can be compared with laboratory data to identify which ices are present in the molecular cloud.

In this study, the team targeted ices buried in a particularly cold, dense and difficult to investigate region of the Chamaeleon I molecular cloud, a region approximately 600 light-years from Earth which is currently in the process of forming dozens of young stars.

Along with star forming comes planet forming and the perspective for the researchers in the IceAge collaboration is basically to identify the role the ice plays in gathering the molecules necessary to form life.

"This study confirms that interstellar grains of dust are catalysts for the forming of complex molecules in the very diffuse gas in these clouds, something we see in the lab as well," Sergio Ioppolo explains, associate professor at Aarhus University, contributing with some of the experiments in the lab that were compared with the observations.

The sensitivity of JWST was an absolutely necessary precondition for the discovery

"We simply couldn't have observed these ices without Webb," elaborated Klaus Pontoppidan, JWST project scientist at the Space Telescope Science Institute, Baltimore, USA, who was involved in this research.

"The ices show up as dips against a continuum of background starlight. In regions that are this cold and dense, much of the light from the background star is blocked and Webb's exquisite sensitivity was necessary to detect the starlight and therefore identify the ices in the molecular cloud."

The IceAge team has already planned more observations with both Webb and other telescopes.

"These observations together with further laboratory studies will tell us which mixture of ices -- and therefore which elements -- can eventually be delivered to the surfaces of terrestrial exoplanets or incorporated into the atmospheres of giant gas or ice planets.

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Meteorites reveal likely origin of Earth's volatile chemicals

By analysing meteorites, Imperial researchers have uncovered the likely far-flung origin of Earth's volatile chemicals, some of which form the building blocks of life.

They found that around half the Earth's inventory of the volatile element zinc came from asteroids originating in the outer Solar System -- the part beyond the asteroid belt that includes the planets Jupiter, Saturn, and Uranus. This material is also expected to have supplied other important volatiles such as water.

Volatiles are elements or compounds that change from solid or liquid state into vapour at relatively low temperatures. They include the six most common elements found in living organisms, as well as water. As such, the addition of this material will have been important for the emergence of life on Earth.

Prior to this, researchers thought that most of Earth's volatiles came from asteroids that formed closer to the Earth. The findings reveal important clues about how Earth came to harbour the special conditions needed to sustain life.

Senior author Professor Mark Rehka?mper, of Imperial College London's Department of Earth Science and Engineering, said: "Our data show that about half of Earth's zinc inventory was delivered by material from the outer Solar System, beyond the orbit of Jupiter. Based on current models of early Solar System development, this was completely unexpected."

Previous research suggested that the Earth formed almost exclusively from inner Solar System material, which researchers inferred was the predominant source of Earth's volatile chemicals. In contrast, the new findings suggest the outer Solar System played a bigger role than previously thought.

Professor Rehka?mper added: "This contribution of outer Solar System material played a vital role in establishing the Earth's inventory of volatile chemicals. It looks as though without the contribution of outer Solar System material, the Earth would have a much lower amount of volatiles than we know it today -- making it drier and potentially unable to nourish and sustain life."

The findings are published today in Science.

To carry out the study, the researchers examined 18 meteorites of varying origins -- eleven from the inner Solar System, known as non-carbonaceous meteorites, and seven from the outer Solar System, known as carbonaceous meteorites.

For each meteorite they measured the relative abundances of the five different forms -- or isotopes -- of zinc. They then compared each isotopic fingerprint with Earth samples to estimate how much each of these materials contributed to the Earth's zinc inventory. The results suggest that while the Earth only incorporated about ten per cent of its mass from carbonaceous bodies, this material supplied about half of Earth's zinc.

The researchers say that material with a high concentration of zinc and other volatile constituents is also likely to be relatively abundant in water, giving clues about the origin of Earth's water.

First author on the paper Rayssa Martins, PhD candidate at the Department of Earth Science and Engineering, said: "We've long known that some carbonaceous material was added to the Earth, but our findings suggest that this material played a key role in establishing our budget of volatile elements, some of which are essential for life to flourish."

Next the researchers will analyse rocks from Mars, which harboured water 4.1 to 3 billion years ago before drying up, and the Moon. Professor Rehka?mper said: "The widely held theory is that the Moon formed when a huge asteroid smashed into an embryonic Earth about 4.5 billion years ago. Analysing zinc isotopes in moon rocks will help us to test this hypothesis and determine whether the colliding asteroid played an important part in delivering volatiles, including water, to the Earth."

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Origins of the building blocks of life

A new study led by Southwest Research Institute Research Scientist Dr. Danna Qasim posits that interstellar cloud conditions may have played a significant role on the presence of key building blocks of life in the solar system.

"Carbonaceous chondrites, some of the oldest objects in the universe, are meteorites that are thought to have contributed to the origins of life. They contain several different molecules and organic substances, including amines and amino acids, which are key building blocks of life that were critical to creating life on Earth. These substances are necessary to create proteins and muscle tissue," Qasim said.

Most meteorites are fragments of asteroids that broke apart long ago in the asteroid belt, located between Mars and Jupiter. Such fragments orbit the Sun -- sometimes for millions of years -- before colliding with Earth.

One of the questions Qasim and others are trying to answer is how amino acids got into the carbonaceous chondrites in the first place. Because most meteorites come from asteroids, scientists have attempted to reproduce amino acids by simulating asteroid conditions in a laboratory setting, a process called "aqueous alteration."

"That method hasn't been 100% successful," Qasim said. "However, the make-up of asteroids originated from the parental interstellar molecular cloud, which was rich in organics. While there's no direct evidence of amino acids in interstellar clouds, there is evidence of amines. The molecular cloud could have provided the amino acids in asteroids, which passed them on to meteorites."

To determine to what extent amino acids formed from asteroid conditions and to what extent they were inherited from the interstellar molecular cloud, Qasim simulated the formation of amines and amino acids as it would occur in the interstellar molecular cloud.

"I created ices that are very common in the cloud and irradiated them to simulate the impact of cosmic rays," explained Qasim, who conducted the experiment while working at NASA's Goddard Space Flight Center in Greenbelt, Maryland, between 2020 and 2022. "This caused the molecules to break up and recombine into larger molecules, which ultimately created an organic residue."

Qasim then processed the residue again by recreating asteroid conditions through aqueous alteration and studied the substance, looking for amines and amino acids.

"No matter what kind of asteroid processing we did, the diversity of amines and amino acids from the interstellar ice experiments remained constant," she said. "That tells us that interstellar cloud conditions are quite resilient to asteroid processing. These conditions could have influenced the distribution of amino acids we find in meteorites."

However, the individual abundances of amino acids doubled, suggesting the asteroid processing influences the amount of amino acids present.

"Essentially we have to consider both the interstellar cloud conditions and processing by the asteroid to best interpret the distribution," she said.

Qasim looks forward to studies of asteroid samples from missions such as OSIRIS-REx, which is currently on its way back to Earth to deliver samples from the asteroid Bennu here in September, and Hayabusa2, which recently returned from the asteroid Ryugu, to better understand the role the interstellar cloud played in distributing the building blocks of life.

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Meteorites plus gamma rays could have given Earth the building blocks for life

Even as detailed images of distant galaxies from the James Webb Space Telescope show us more of the greater universe, scientists still disagree about how life began here on Earth. One hypothesis is that meteorites delivered amino acids -- life's building blocks -- to our planet. Now, researchers reporting in ACS Central Science have experimentally shown that amino acids could have formed in these early meteorites from reactions driven by gamma rays produced inside the space rocks.

Ever since Earth was a newly formed, sterile planet, meteorites have been hurtling through the atmosphere at high speeds toward its surface. If the initial space debris had included carbonaceous chondrites -- a class of meteorite whose members contain significant amounts of water and small molecules, such as amino acids -- then it could have contributed to the evolution of life on Earth. However, the source of amino acids in meteorites has been hard to pinpoint. In previous lab experiments, Yoko Kebukawa and colleagues showed that reactions between simple molecules, such as ammonia and formaldehyde, can synthesize amino acids and other macromolecules, but liquid water and heat are required. Radioactive elements, such as aluminum-26 (26Al) -- which is known to have existed in early carbonaceous chondrites -- release gamma rays, a form of high-energy radiation, when they decay. This process could have provided the heat needed to make biomolecules. So, Kebukawa and a new team wanted to see whether radiation could have contributed to the formation of amino acids in early meteorites.

The researchers dissolved formaldehyde and ammonia in water, sealed the solution in glass tubes and then irradiated the tubes with high-energy gamma rays produced from the decay of cobalt-60. They found that the production of α-amino acids, such as alanine, glycine, α-aminobutyric acid and glutamic acid, and β-amino acids, such as β-alanine and β-aminoisobutyric acid, rose in the irradiated solutions as the total gamma-ray dose increased. Based on these results and the expected gamma ray dose from the decay of 26Al in meteorites, the researchers estimated that it would have taken between 1,000 and 100,000 years to produce the amount of alanine and β-alanine found in the Murchison meteorite, which landed in Australia in 1969. This study provides evidence that gamma ray-catalyzed reactions can produce amino acids, possibly contributing to the origin of life on Earth, the researchers say.

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Researchers reveal the origin story for carbon-12, a building block for life

With the help of the world's most powerful supercomputer and new artificial intelligence techniques, an international team of researchers has theorized how the extreme conditions in stars produce carbon-12, which they describe as "a critical gateway to the birth of life."

The researchers' fundamental question: "How does the cosmos produce carbon-12?" said James Vary, a professor of physics and astronomy at Iowa State University and a longtime member of the research collaboration.

"It turns out it's not easy to produce carbon-12," Vary said.

It takes the extreme heat and pressures inside stars or in stellar collisions and explosions to create emergent, unstable, excited-state carbon nuclei with three loosely linked clumps, each with two protons and two neutrons. A fraction of those unstable carbon nuclei can shoot off a little extra energy in the form of gamma rays and become stable carbon-12, the stuff of life.

A paper recently published by the online journal Nature Communications describes the researchers' supercomputer simulations and resulting theory for the nuclear structure of carbon that favors its formation in the cosmos. The corresponding author is Takaharu Otsuka of the University of Tokyo, the RIKEN Nishina Center for Accelerator-Based Science and the Advanced Science Research Center of the Japan Atomic Energy Agency.

The paper describes how alpha particles -- helium-4 atoms, with two protons and two neutrons -- can cluster to form much heavier atoms, including an unstable, excited carbon-12 state known as the Hoyle state (predicted by theoretical astrophysicist Fred Hoyle in 1953 as a precursor to life as we know it).

The researchers write that this alpha-particle clustering "is a very beautiful and fascinating idea and is indeed plausible because the (alpha) particle is particularly stable with a large binding energy."

To test the theory, the researchers ran supercomputer simulations, including calculations on the Fugaku supercomputer at the RIKEN Center for Computational Science in Kobe, Japan. Fugaku is listed as the most powerful supercomputer in the world and is three times more powerful than No. 2, according to the latest TOP500 supercomputer rankings.

Vary said the researchers also did their work ab initio, or from first principles, meaning their calculations were based on known science and didn't include additional assumptions or parameters.

They also developed techniques in statistical learning, a branch of computational artificial intelligence, to reveal alpha clustering the Hoyle state and the eventual production of stable carbon-12.

Vary said the team has worked for more than a decade to develop its software, refine its supercomputer codes, run its calculations and work out smaller problems while building up to the current work.

"There's a lot of subtlety -- a lot of beautiful interactions going on in there," Vary said.

All the calculations, physical quantities and theoretical subtlety match what experimental data there is in this corner of nuclear physics, the researchers wrote.

So they think they have some basic answers about the origins of carbon-12. Vary said that should lead to more studies looking for "fine-grain detail" about the process and how it works.

Was carbon production, for example, mostly the result of internal processes in stars? Vary asked. Or was it supernova star explosions? Or collisions of super-dense neutron stars?

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How life came to Earth

Researchers have discovered a new clue in the search for the origin of life by showing that peptides can form on dust under conditions such as those prevailing in outer space. These molecules, which are one of the basic building blocks of all life, may therefore not have originated on our planet at all, but possibly in cosmic molecular clouds.

Chains of amino acids

All life as we know it consists of the same chemical building blocks. These include peptides, which perform various completely different functions in the body -- transporting substances, accelerating reactions or forming stabilising scaffolds in cells. Peptides consist of individual amino acids arranged in a specific order. The exact order determines a peptide's eventual properties.

How these versatile biomolecules came into being is one of the questions about the origin of life. Amino acids, nucleobases and various sugars found in meteoroids, for example, show that this origin could be extraterrestrial in nature. However, for a peptide to be formed from individual amino acid molecules, very special conditions are required that were previously assumed to be more likely to exist on Earth.

The first step requires water, while for the second step, there must be no water

"Water plays an important role in the conventional way in which peptides are created," says Dr Serge Krasnokutski of the Laboratory Astrophysics and Cluster Physics Group of the Max Planck Institute for Astronomy at the University of Jena. In this process, individual amino acids combine to form a chain. For this to happen, one water molecule must be removed each time. "Our quantum chemical calculations have now shown that the amino acid glycine can be formed through a chemical precursor -- called an amino ketene -- combining with a water molecule. Put simply: in this case, water must be added for the first reaction step, and water must be removed for the second."

With this knowledge, the team led by the physicist Krasnokutski has now been able to demonstrate a reaction pathway that can take place under cosmic conditions and does not require water.

"Instead of taking the chemical detour in which amino acids are formed, we wanted to find out whether amino ketene molecules could not be formed instead and combine directly to form peptides," says Krasnokutski, describing the basic idea behind the work. He adds: "And we did this under the conditions that prevail in cosmic molecular clouds, that is to say on dust particles in a vacuum, where the corresponding chemicals are present in abundance: carbon, ammonia and carbon monoxide."

In an ultra-high vacuum chamber, substrates that serve as a model for the surface of dust particles were brought together with carbon, ammonia and carbon monoxide at about one quadrillionth of normal air pressure and minus 263 degrees Celsius.

"Investigations showed that under these conditions, the peptide polyglycine was formed from the simple chemicals," Krasnokutski says. "These are therefore chains of the very simple amino acid glycine, and we observed different lengths. The longest specimens consisted of eleven units of the amino acid."

In this experiment, the german team was also able to detect the suspected amino ketene. "The fact that the reaction can take place at such low temperatures at all is due to the amino ketene molecules being extremely reactive. They combine with each other in an effective polymerisation. The product of this is polyglycine."

Quantum mechanical tunnelling effect might play a role

"It was nevertheless surprising to us that the polymerisation of amino ketene could happen so easily under such conditions," says Krasnokutski. "This is because an energy barrier actually has to be overcome for this to happen. However, it may be that we are helped in this by a special effect of quantum mechanics. In this special reaction step, a hydrogen atom changes its place. However, it is so small that, as a quantum particle, it could not overcome the barrier but was simply able to cross it, so to speak, through the tunnelling effect."

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Life arose on hydrogen energy, researchers suggest

How did the first chemical reactions get started at the origin of life and what was their source of energy? Researchers at the Heinrich Heine University Düsseldorf (HHU) have reconstructed the metabolism of the last universal common ancestor, LUCA. They found that almost all chemical steps used by primordial life to piece together the molecular building blocks of cells are energy releasing reactions. This identified the long-sought source of energy needed to drive these reactions forward, which has been hiding in plain sight. The energy required to synthesize the building blocks of life comes from within metabolism itself, as long as one essential starting compound is included. The secret ingredient that releases the energy from within at life's origin is the cleanest, greenest, newest and oldest of all energy carriers: Hydrogen gas, H2.

The team of Prof. Dr. William Martin in the Institute for Molecular Evolution at the HHU investigates how and where life arose on the early Earth. Their approach is experimental and computational. In the laboratory, they run chemical experiments to investigate reactions between hydrogen and carbon dioxide, CO2, using catalysts and conditions found in submarine hydrothermal vents. At the computer, they have developed a form of molecular archaeology that allows them to uncover the many different traces of primordial life that are preserved in the proteins, DNA and chemical reactions of modern cells.

In their latest work, they investigated the question of what kind of chemical environment fostered the chemical reactions that gave rise to metabolism, and later to LUCA itself, and where the energy came from that was needed to drive those reactions forward. To do that, they looked not at genes, but at the information contained within the chemical reactions of life themselves. They identified 402 metabolic reactions that have gone virtually unchanged since the origin of life roughly 4 billion years ago. Because these reactions are common to all cells, they were also present in LUCA. They shed light on how primordial life dealt with energy in metabolism and where it obtained the energy needed to make life's chemical reactions go forward.

Jessica Wimmer, a PhD student in the institute and lead author on the new paper, was particularly interested in the energy balance of LUCA's metabolic reactions, because all life requires energy. For that she made a catalogue of the 402 reactions that the simple and ancient among modern cells -- bacteria and archaea -- use to construct the building blocks of life: the 20 amino acids, the bases of DNA and RNA, and the 18 vitamins (cofactors) that are essential for metabolism. In the most primitive of modern cells, and in Wimmer's computer analyses, these compounds are synthesized from simple molecules that are present in the modern environment and that were also present in hydrothermal vents on the early Earth: hydrogen (H2), carbon dioxide (CO2) and ammonia (NH3). The result was the metabolic network of LUCA.

When asked about the motivation behind the central question of the new study, Jessica Wimmer says: "We wanted to know where the energy came from that drove primordial metabolism forward. At the very onset of metabolic reactions some 4 billion years ago, there were no proteins or enzymes to catalyze reactions because they had not yet evolved. Metabolism had to arise from reactions that could take place in the environment, perhaps with help from inorganic catalysts. But catalysts or not, in order to go forward, the reactions have to release energy. Where did that energy come from? There have been lots of suggestions for possible sources of metabolic energy in the literature. But nobody ever looked into the reactions of metabolism itself." To find sources of energy in metabolic reactions, the team calculated the amount of free energy, also called Gibbs energy, that is released or consumed in each reaction.

The result: LUCA's metabolism required no external source of energy such as UV light, meteorite impacts, volcanic eruptions, or radioactivity. On the contrary, in an environment typical of many modern submarine hydrothermal vents, the energy needed for the reactions of metabolism to go forward stems from within metabolism itself. Stated another way, almost all of LUCA's metabolic reactions liberate energy all by themselves: the energy for life stems from life itself. Martin, senior author of the study, says: "That is exciting, because the 400 interconnected reactions of central metabolism, which seem so hopelessly complex upon first encounter, suddenly reveal a natural tendency to unfold all by themselves under the right conditions."

To arrive at that conclusion, the team had to first investigate the energetics of the 402 reactions using computer programs that simulate different environmental conditions, so as to distinguish energetically favorable from unfavorable combinations. This is important because whether or not a reaction releases energy often depends upon environmental conditions. They surveyed conditions ranging from pH 1 (acidic) to pH 14 (alkaline), temperatures from 25 to 100 °C, and different relative amounts of reactants to products. They looked with particular care at the energetic role of hydrogen. Wimmer: "Without hydrogen, nothing happens at all, because hydrogen is required to get carbon from CO2 incorporated into metabolism in the first place."

The energetically optimal conditions fall within an alkaline pH range around pH 9 and a temperature around 80 °C, with hydrogen required for CO2 fixation. Putting this result in context, Martin explains: "This is almost exactly what we see at Lost City, a H2-producing hydrothermal field in the Mid-Atlantic. In an environment like that, about 95-97 % of LUCA's metabolic reactions could go forward spontaneously, that is, without the need for any other source of energy. In the abyssal darkness of hydrothermal systems, H2 is chemical sunlight. Modern energy research exploits exactly the same properties of hydrogen as life does. It is just that life has four billion years of experience with hydrogen technology, while we are just getting started."

Read more at Science Daily

Device mimics life's first steps in outer space

 A device developed by scientists at the CY Cergy Paris University and Paris Observatory promises insight into how the building blocks of life form in outer space.

In an article published in Review of Scientific Instruments, by AIP Publishing, the scientists detail how VENUS -- an acronym of the French phrase "Vers de Nouvelles Syntheses," which means "toward new syntheses" -- mimics how molecules come together in the freezing darkness of interstellar space.

"We try to simulate how complex organic molecules are formed in such a harsh environment," said Emanuele Congiu, one of the authors and an astrophysicist at the observatory. "Observatories can see a lot of molecules in space. What we do not understand yet, or fully, is how they formed in this harsh environment."

VENUS has a chamber designed to replicate the strong vacuum of space, while holding a frigid temperature that is set lower than minus 400 degrees Fahrenheit (10 kelvins). It uses up to five beams to deliver atoms or molecules onto a tiny sliver of ice without disturbing that environment.

That process, Congiu said, replicates how molecules form on the ice that sits atop tiny dust particles found inside interstellar clouds. VENUS is the first device to do the replication with more than three beams, which lets researchers simulate more complicated interactions.

Over the past 50 years, nearly 200 different molecular species have been discovered in the star-forming regions of space. Some of them, the so-called "prebiotic species," are believed by scientists to be involved in the processes that lead to the early forms of life.

A key use of the VENUS device will be working in concert with scientists who discover molecular reactions in space but need a fuller understanding of what they have observed. It specifically mentions NASA's launch of the James Webb Space Telescope, which is scheduled for 2021. The largest and most powerful space telescope ever launched, it is expected to dramatically expand scientists' knowledge of the universe.

"What we can do in the lab in one day takes thousands of years in space," Congiu said. "Our work in the lab can complement the wealth of data that comes from the space observatories. Otherwise, astronomers would not be able to interpret all of their observations. Researchers who make observations can ask us to simulate a certain reaction, to see if what they think they see is real or not."

From Science Daily

Building blocks of life can form long before stars

 An international team of scientists have shown that glycine, the simplest amino acid and an important building block of life, can form under the harsh conditions that govern chemistry in space.

The results, published in Nature Astronomy, suggest that glycine, and very likely other amino acids, form in dense interstellar clouds well before they transform into new stars and planets.

Comets are the most pristine material in our Solar System and reflect the molecular composition present at the time our Sun and planets were just about to form. The detection of glycine in the coma of comet 67P/Churyumov-Gerasimenko and in samples returned to Earth from the Stardust mission suggests that amino acids, such as glycine, form long before stars. However until recently, it was thought that glycine formation required energy, setting clear constraints to the environment in which it can be formed.

In the new study the international team of astrophysicists and astrochemical modelers, mostly based at the Laboratory for Astrophysics at Leiden Observatory, the Netherlands, have shown that it is possible for glycine to form on the surface of icy dust grains, in the absence of energy, through 'dark chemistry'. The findings contradict previous studies that have suggested UV radiation was required to produce this molecule.

Dr Sergio Ioppolo, from Queen Mary University of London and lead author of the article, said: "Dark chemistry refers to chemistry without the need of energetic radiation. In the laboratory we were able to simulate the conditions in dark interstellar clouds where cold dust particles are covered by thin layers of ice and subsequently processed by impacting atoms causing precursor species to fragment and reactive intermediates to recombine."

The scientists first showed methylamine, the precursor species of glycine that was detected in the coma of the comet 67P, could form. Then, using a unique ultra-high vacuum setup, equipped with a series of atomic beam lines and accurate diagnostic tools, they were able to confirm glycine could also be formed, and that the presence of water ice was essential in this process.

Further investigation using astrochemical models confirmed the experimental results and allowed the researchers to extrapolate data obtained on a typical laboratory timescale of just one day to interstellar conditions, bridging millions of years. "From this we find that low but substantial amounts of glycine can be formed in space with time," said Professor Herma Cuppen from Radboud University, Nijmegen, who was responsible for some of the modelling studies within the paper.

"The important conclusion from this work is that molecules that are considered building blocks of life already form at a stage that is well before the start of star and planet formation," said Harold Linnartz, Director of the Laboratory for Astrophysics at Leiden Observatory. "Such an early formation of glycine in the evolution of star-forming regions implies that this amino acid can be formed more ubiquitously in space and is preserved in the bulk of ice before inclusion in comets and planetesimals that make up the material from which ultimately planets are made."

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Scientists have discovered the origins of the building blocks of life

Rutgers researchers have discovered the origins of the protein structures responsible for metabolism: simple molecules that powered early life on Earth and serve as chemical signals that NASA could use to search for life on other planets.

Their study, which predicts what the earliest proteins looked like 3.5 billion to 2.5 billion years ago, is published in the journal Proceedings of the National Academy of Sciences.

The scientists retraced, like a many thousand piece puzzle, the evolution of enzymes (proteins) from the present to the deep past. The solution to the puzzle required two missing pieces, and life on Earth could not exist without them. By constructing a network connected by their roles in metabolism, this team discovered the missing pieces.

"We know very little about how life started on our planet. This work allowed us to glimpse deep in time and propose the earliest metabolic proteins," said co-author Vikas Nanda, a professor of Biochemistry and Molecular Biology at Rutgers Robert Wood Johnson Medical School and a resident faculty member at the Center for Advanced Biotechnology and Medicine. "Our predictions will be tested in the laboratory to better understand the origins of life on Earth and to inform how life may originate elsewhere. We are building models of proteins in the lab and testing whether they can trigger reactions critical for early metabolism."

A Rutgers-led team of scientists called ENIGMA (Evolution of Nanomachines in Geospheres and Microbial Ancestors) is conducting the research with a NASA grant and via membership in the NASA Astrobiology Program. The ENIGMA project seeks to reveal the role of the simplest proteins that catalyzed the earliest stages of life.

"We think life was built from very small building blocks and emerged like a Lego set to make cells and more complex organisms like us," said senior author Paul G. Falkowski, ENIGMA principal investigator and a distinguished professor at Rutgers University-New Brunswick who leads the Environmental Biophysics and Molecular Ecology Laboratory. "We think we have found the building blocks of life -- the Lego set that led, ultimately, to the evolution of cells, animals and plants."

The Rutgers team focused on two protein "folds" that are likely the first structures in early metabolism. They are a ferredoxin fold that binds iron-sulfur compounds, and a "Rossmann" fold, which binds nucleotides (the building blocks of DNA and RNA). These are two pieces of the puzzle that must fit in the evolution of life.

Proteins are chains of amino acids and a chain's 3D path in space is called a fold. Ferredoxins are metals found in modern proteins and shuttle electrons around cells to promote metabolism. Electrons flow through solids, liquids and gases and power living systems, and the same electrical force must be present in any other planetary system with a chance to support life.

There is evidence the two folds may have shared a common ancestor and, if true, the ancestor may have been the first metabolic enzyme of life.

Read more at Science Daily

Life's building blocks may have formed in interstellar clouds

An experiment shows that one of the basic units of life -- nucleobases -- could have originated within giant gas clouds interspersed between the stars.

Essential building blocks of DNA -- compounds called nucleobases -- have been detected for the first time in a simulated environment mimicking gaseous clouds that are found interspersed between stars. The finding, published in the journal Nature Communications, brings us closer to understanding the origins of life on Earth.

"This result could be key to unravelling fundamental questions for humankind, such as what organic compounds existed during the formation of the solar system and how they contributed to the birth of life on Earth" says Yasuhiro Oba of Hokkaido University's Institute of Low Temperature Science.

Scientists have already detected some of the basic organic molecules necessary for the beginnings of life in comets, asteroids, and in interstellar molecular clouds: giant gaseous clouds dispersed between stars. It is thought that these molecules could have reached Earth through meteorite impacts some four billion years ago, providing key ingredients for the chemical cocktail that gave rise to life. Learning how these molecules formed is vital to understanding the origins of life.

The basic structural unit of DNA and RNA is called a nucleotide and is composed of a nucleobase, a sugar, and a phosphate group. Previous studies mimicking the expected conditions in interstellar molecular clouds have detected the presence of sugar and phosphate, but not of nucleobases.

Now, Yasuhiro Oba and colleagues at Hokkaido University, Kyushu University, and the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) have used advanced analytical methods to detect the fundamental nucleobases in a simulated interstellar cloud environment.

The team conducted their experiments in an ultra-high vacuum reaction chamber. A gaseous mixture of water, carbon monoxide, ammonia, and methanol was continuously supplied onto a cosmic-dust analogue at a temperature of -263° Celsius. Two deuterium discharge lamps attached to the chamber supplied vacuum ultraviolet light to induce chemical reactions. The process led to the formation of an icy film on the dust analogue inside the chamber.

The team used a high-resolution mass spectrometer and a high-performance liquid chromatograph to analyse the product that formed on the substrate after warming it to room temperature. Recent advances in these technological tools allowed them to detect the presence of the nucleobases cytosine, uracil, thymine, adenine, xanthine, and hypoxanthine. They also detected amino acids, which are the building blocks of proteins, and several kinds of dipeptide, or a dimer of amino acid, in the same product.

The team suspects that past experiments simulating interstellar molecular cloud environments would have produced nucleobases, but that the analytical tools used were not sensitive enough to detect them in complex mixtures.

"Our findings suggest that the processes we reproduced could lead to the formation of the molecular precursors of life," says Yasuhiro Oba. "The results could improve our understanding of the early stages of chemical evolution in space."

From Science Daily