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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Earth prefers to serve life in XXS and XXL sizes

Life comes in all shapes in sizes, but some sizes are more popular than others, new research from the University of British Columbia has found.

In the first study of its kind published today in PLOS ONE, Dr. Eden Tekwa, who conducted the study as a postdoctoral fellow at UBC's department of zoology, surveyed the body sizes of all Earth's living organisms, and uncovered an unexpected pattern. Contrary to what current theories can explain, our planet's biomass -- the material that makes up all living organisms -- is concentrated in organisms at either end of the size spectrum.

"The smallest and largest organisms significantly outweigh all other organisms," said Dr. Tekwa, lead author of "The size of life," and now a research associate with McGill University's department of biology. "This seems like a new and emerging pattern that needs to be explained, and we don't have theories for how to explain it right now. Current theories predict that biomass would be spread evenly across all body sizes."

In addition to challenging our understanding of how life is distributed, these results have important implications for predicting the effects and impacts of climate change. "Body size governs a lot of global processes as well as local processes, including the rate at which carbon gets sequestered, and how the function and stability of ecosystems might be affected by the composition of living things," said Dr. Tekwa. "We need to think about how body size biomass distribution will change under environmental pressures."

"Life constantly amazes us, including the incredible range of sizes that it comes in," says senior author Dr. Malin Pinsky, associate professor in the department of ecology, evolution, and natural resources at Rutgers University. "If the tiniest microbe was the size of the period at the end of this sentence, the largest living organism, a sequoia tree, would be the size of the Panama Canal."

To obtain their results, Dr. Tekwa spent five years compiling and analyzing data about the size and biomass of every type of living organism on the planet -- from tiny one-celled organisms like soil archaea and bacteria to large organisms like blue whales and sequoia trees. They found that the pattern favouring large and small organisms held across all types of species, and was more pronounced in land-based organisms than in marine environments. Interestingly, maximum body size seemed to reach the same upper limits across multiple species and environments.

"The largest body sizes appear across multiple species groups, and their maximum body sizes are all within a relatively narrow range," Dr. Tekwa noted. "Trees, grasses, underground fungi, mangroves, corals, fish and marine mammals all have similar maximum body sizes. This might suggest that there is a universal upper size limit due to ecological, evolutionary or biophysical limitations."

Dr. Tekwa was also able to uncover some intriguing details about the distribution of life in various ecosystems. "Even though corals occur in only a small fraction of the ocean, it turns out that they have about the same biomass as all the fish in the ocean," said Dr. Tekwa. "This illustrates how important the balance of biomass is in the oceans. Corals support a lot of fish diversity, so it's really interesting that those two organisms have almost the same biomass."

As for humans, we already know we comprise a relatively small biomass, but our size among all living things reveals our place in the global biome. "We belong to the size range that comprises the highest biomass, which is a relatively large body size," said Dr. Tekwa.

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A star is born: Study reveals complex chemistry inside 'stellar nurseries'

An international team of researchers has uncovered what might be a critical step in the chemical evolution of molecules in cosmic "stellar nurseries." In these vast clouds of cold gas and dust in space, trillions of molecules swirl together over millions of years. The collapse of these interstellar clouds eventually gives rise to young stars and planets.

Like human bodies, stellar nurseries contain a lot of organic molecules, which are made up mostly of carbon and hydrogen atoms. The group's results, published Feb. 6 in the journal Nature Astronomy, reveal how certain large organic molecules may form inside these clouds. It's one tiny step in the eons-long chemical journey that carbon atoms undergo -- forming in the hearts of dying stars, then becoming part of planets, living organisms on Earth and perhaps beyond.

"In these cold molecular clouds, you're creating the first building blocks that will, in the end, form stars and planets," said Jordy Bouwman, research associate at the Laboratory for Atmospheric and Space Physics (LASP) and assistant professor in the Department of Chemistry at the University of Colorado Boulder.

For the new study, Bouwman and his colleagues took a deep dive into one stellar nursery in particular: the Taurus Molecular Cloud (TMC-1). This region sits in the constellation Taurus and is roughly 440 light years (more than 2 quadrillion miles) from Earth. This chemically complex environment is an example of what astronomers call an "accreting starless core." Its cloud has begun to collapse, but scientists haven't yet detected embryonic stars emerging inside it.

The team's findings hinge on a deceptively simple molecule called ortho-benzyne. Drawing on experiments on Earth and computer simulations, the researchers showed that this molecule can readily combine with others in space to form a wide range of larger organic molecules.

Small building blocks, in other words, become big building blocks.

And, Bouwman said, those reactions could be a sign that stellar nurseries are a lot more interesting than scientists give them credit for.

"We're only at the start of truly understanding how we go from these small building blocks to larger molecules," he said. "I think we'll find that this chemistry is so much more complex than we thought, even at the earliest stages of star formation."

Fateful observation

Bouwman is a cosmochemist, studying a field that blends chemistry and astronomy to understand the churning chemical reactions that happen deep in space.

On the surface, he said, cold molecular clouds might not seem like a hotbed of chemical activity. As their name suggests, these galactic primordial soups tend to be frigid, often hovering around -263 degrees Celsius (about -440 degrees Fahrenheit), just 10 degrees above absolute zero. Most reactions need at least a little bit of heat to get a kick-start.

But cold or not, complex chemistry seems to be happening in stellar nurseries. TMC-1, in particular, contains surprising concentrations of relatively large organic molecules with names like fulvenallene and 1- and 2-ethynylcyclopentadiene. Chemists call them "five-membered ring compounds" because they each contain a ring of carbon atoms shaped like a pentagon.

"Researchers kept detecting these molecules in TMC-1, but their origin was unclear," Bouwman said.

Now, he and his colleagues think they have an answer.

In 2021, researchers using the Yebes 40-metre Radiotelescope in Spain found an unexpected molecule hiding in the clouds of gas of TMC-1: ortho-benzyne. Bouwman explained that this small molecule, made up of a ring of six carbon atoms with four hydrogens, is one of the extroverts of the chemistry world. It easily interacts with a number of other molecules and doesn't require a lot of heat to do so.

"There's no barrier to reaction," Bouwman said. "That means that it has the potential to drive complex chemistry in cold environments."

Identifying the culprit

To find out what kind of complex chemistry was happening in TMC-1, Bouwman and his colleagues -- who hail from the United States, Germany, the Netherlands and Switzerland -- turned to a technique called "photoelectron photoion coincidence spectroscopy." The team used light generated by a giant facility called a synchrotron light source to identify the products of chemical reactions. They saw that ortho-benzyne and methyl radicals, another common constituent of molecular clouds, readily combine to form larger and more complex organic compounds.

"We knew we were onto something good," Bouwman said.

The team then drew on computer models to explore the role of ortho-benzyne in a stellar nursery spread out over several light years deep in space. The results were promising: The models generated clouds of gas containing roughly the same mix of organic molecules that astronomers had observed in TMC-1 using telescopes.

Ortho-benzyne, in other words, seems to be a prime candidate for driving the gas-phase organic chemistry that occurs within these stellar nurseries, Bouwman said.

He added that scientists still have a lot of work to do to fully understand all the reactions happening in TMC-1. He wants to examine, for example, how organic molecules in space also pick up nitrogen atoms -- key components of the DNA and amino acids of living organisms on Earth.

"Our findings may just change the view on what ingredients we have in the first place to form new stars and new planets," Bouwman said.

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