- Largest Martian meteorite fetches more than €4.3 million at auction Euronews.com
- Largest Mars rock ever found on Earth sells for $4.3m at auction BBC
- The biggest piece of Mars on Earth is going up for auction in New York AP News
- Largest known Martian meteorite on Earth sells for $5.3 million at auction Live Science
- Who wants to buy a piece of Mars? National Geographic
Category: 7. Science
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Largest Martian meteorite fetches more than €4.3 million at auction – Euronews.com
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From Global Climate Models (GCMs) to Exoplanet Spectra with the Global Emission Spectra (GlobES)
For simulated transit observations, the GlobES app performs RT calculations across the terminator and integrates the different spectra employing equal weights. For direct imaging and secondary eclipse simulations, the algorithm performs RT simulations across the whole observable disk, and the individual spectra are integrated considering the projected area of each bin. An example of surface temperature maps at various phase angles from Suissa et al. (2020) produced from the ExoCAM GCM (Wolf et al., 2022) are also shown. — astro-ph.EP
In the quest to understand the climates and atmospheres of exoplanets, 3D global climate models (GCMs) have become indispensable.
The ability of GCMs to predict atmospheric conditions complements exoplanet observations, creating a feedback loop that enhances our understanding of exoplanetary atmospheres and their environments.
This paper discusses the capabilities of the Global Exoplanet Spectra (GlobES) module of the Planetary Spectrum Generator (PSG), which incorporates 3D atmospheric and surface information into spectral simulations, offering a free, accessible tool for the scientific community to study realistic planetary atmospheres.
Through detailed case studies, including simulations of TRAPPIST1 b, TRAPPIST-1 e, and Earth around Sun, this paper demonstrates the use of GlobES and its effectiveness in simulating transit, emission and reflected spectra, thus supporting the ongoing development and refinement of observational strategies using the James Webb Space Telescope (JWST) and future mission concept studies (e.g., Habitable Worlds Observatory [HWO]) in exoplanet research.
Ray-tracing through a planetary atmosphere involves layer-by-layer variations in ray length and angles within a spherical atmosphere (gray curved lines), as refraction ‘bends’ the light (red traces) along its path. Depending on the degree of bending, the observer may detect radiation originating from the surface, the TOA, or a background star (e.g., during transit observations). — astro-ph.EP
Thomas J. Fauchez, Geronimo L. Villanueva, Vincent Kofman, Gabriella Suissa, Ravi K. Kopparapu
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2507.09048 [astro-ph.EP] (or arXiv:2507.09048v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2507.09048
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Journal reference: Published in Astronomy and Computing Volume 53, October 2025, 100982
Related DOI:
https://doi.org/10.1016/j.ascom.2025.100982
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Submission history
From: Thomas Fauchez
[v1] Fri, 11 Jul 2025 21:45:16 UTC (6,355 KB)
https://arxiv.org/abs/2507.09048
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Free Floating or Merely Detached?
Example evolution of an unstable system with 5 one-Neptune-mass planets. Top: the semi-major axes of individual planets are plotted as solid lines. Orbits’ radial extents between pericenter and apocenter are indicated by the corresponding shaded regions. The black dashed line indicates the semi-major axis of an orbit with the same binding energy as the initial five-planet system. Bottom: planets’ orbital inclinations, measured relative to the system’s initial invariable plane, as functions of time. — astro-ph.EP
Microlensing surveys suggest the presence of a surprisingly large population of free-floating planets, with a rate of about two Neptunes per star.
The origin of such objects is not known, neither do we know if they are truly unbound or are merely orbiting at large separations from their host stars. Here, we investigate planet-planet scattering as a possible origin through numerical simulations of unstable multi-planet systems.
We find that planet ejection by scattering can be slow, often taking more than billions of years for Neptune-mass scatterers orbiting at a few AU and beyond. Moreover, this process invariably delivers planets to orbits of hundreds of AU that are protected from further scattering.
We call these “detached” planets. Under the scattering hypothesis, we estimate that about half of the reported “free-floating” Neptunes are not free but merely “detached”.
Sam Hadden, Yanqin Wu
Comments: Submitted to AAS Journals
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2507.08968 [astro-ph.EP] (or arXiv:2507.08968v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2507.08968
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Submission history
From: Sam Hadden
[v1] Fri, 11 Jul 2025 18:54:17 UTC (721 KB)
https://arxiv.org/abs/2507.08968Astrobiology,
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Even Neanderthals had distinct preferences when it came to making dinner, study suggests | Neanderthals
Nothing turns up the heat in a kitchen quite like debating the best way to chop an onion. Now researchers have found even our prehistoric cousins had distinct preferences when it came to preparing food.
Archaeologists studying animal bones recovered from two caves in northern Israel have found different groups of Neanderthals, living around the same time, butchered the same animals in different ways.
“It means that within all the Neanderthal population, you have several distinct groups that have distinct ways of doing things, even for activities that are so related to survival,” said Anaëlle Jallon, the first author of the research, from the Hebrew University of Jerusalem.
Writing in the journal Frontiers in Environmental Archeology, Jallon and colleagues report how they studied cut marks on 249 bone fragments from between 70,000 and 50,000 years ago from Amud cave, and 95 bone fragments dating to between 60,000 and 50,000 years ago from Kebara cave.
The caves are about 70km apart and both were occupied by Neanderthals during the winters. Both groups are known to have used similar flint-based tools.
The team’s analysis of the bones fragments – which were recovered from the caves in the 1990s – confirmed previous findings that burned and fragmented samples were more common in Amud cave, and that both groups had a similar diet featuring animals including mountain gazelles and fallow deer.
But it also provided fresh insights, including that bones from larger animals such as aurochs were more commonly found at Kebara cave. However, Jallon noted it could be that the samples at Kebara were easier to identify, or that Neanderthals at Amud might have butchered such animals elsewhere.
Jallon and colleagues carried out a detailed analysis of the cut marks on 43 and 34 bone samples from Amud and Kebara caves respectively, finding a number of differences in the cut marks between the two sites.
While the researchers say some of the variation related to the type of animal – or body part – being butchered, these factors did not explain all of the differences.
“Even when we compare only the gazelles, and only the long bones of gazelles, we find a higher density of cut marks in [bones from] Amud, with more cut marks that are crossing each other, [and] less cut marks that are straight lines, but more [curved],” said Jallon.
The team suggest a number of possible explanations, including that different groups of Neanderthals had different butchery techniques, involved a different number of individuals when butchering a carcass, or butchered meat in different states of decay.
“It’s either, like, food preferences that lead to different ways of preparing meat and then cutting it, or just differences in the way they learn how to cut meat,” said Jallon.
Dr Matt Pope, of University College London, who was not involved in the work, said the study added to research showing different Neanderthal groups had different ways of making tools, and sometimes used different toolkits.
“These aren’t just cut marks being studied, these are the gestures and movements of the Neanderthal people themselves, as evocative to us as footprints or hand marks on a cave wall,” he said.
“Future research will help to discern between the alternative [explanations for the variations], but the study as it stands is a powerful reminder that there is no monolithic neanderthal culture and that the population contained multiple groups at different times and places, living in the same landscape, with perhaps quite different ways of life.”
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New AI Tool Deciphers Mysteries of Nanoparticle Motion in Liquid Environments
Better understanding their movements is key to developing better medicines, materials, and sensors. But observing and interpreting their motion at the atomic scale has presented scientists with major challenges.
However, researchers in Georgia Tech’s School of Chemical and Biomolecular Engineering (ChBE) have developed an artificial intelligence (AI) model that learns the underlying physics governing those movements.
The team’s research, published in Nature Communications, enables scientists to not only analyze, but also generate realistic nanoparticle motion trajectories that are indistinguishable from real experiments, based on thousands of experimental recordings.
A Clearer Window into the Nanoworld
Conventional microscopes, even extremely powerful ones, struggle to observe moving nanoparticles in fluids. And traditional physics-based models, such as Brownian motion, often fail to fully capture the complexity of unpredictable nanoparticle movements, which can be influenced by factors such as viscoelastic fluids, energy barriers, or surface interactions.
To overcome these obstacles, the researchers developed a deep generative model (called LEONARDO) that can analyze and simulate the motion of nanoparticles captured by liquid-phase transmission electron microscopy (LPTEM), allowing scientists to better understand nanoscale interactions invisible to the naked eye. Unlike traditional imaging, LPTEM can observe particles as they move naturally within a microfluidic chamber, capturing motion down to the nanometer and millisecond.
“LEONARDO allows us to move beyond observation to simulation,” said Vida Jamali, assistant professor and Daniel B. Mowrey Faculty Fellow in ChBE@GT. “We can now generate high-fidelity models of nanoscale motion that reflect the actual physical forces at play. LEONARDO helps us not only see what is happening at the nanoscale but also understand why.”
To train and test LEONARDO, the researchers used a model system of gold nanorods diffusing in water. They collected more than 38,000 short trajectories under various experimental conditions, including different particle sizes, frame rates, and electron beam settings. This diversity allowed the model to generalize across a broad range of behaviors and conditions.
The Power of LEONARDO’s Generative AI
What distinguishes LEONARDO is its ability to learn from experimental data while being guided by physical principles, said study lead author Zain Shabeeb, a PhD student in ChBE@GT. LEONARDO uses a specialized “loss function” based on known laws of physics to ensure that its predictions remain grounded in reality, even when the observed behavior is highly complex or random.
“Many machine learning models are like black boxes in that they make predictions, but we don’t always know why,” Shabeeb said. “With LEONARDO, we integrated physical laws directly into the learning process so that the model’s outputs remain interpretable and physically meaningful.”
LEONARDO uses a transformer-based architecture, which is the same kind of model behind many modern language AI applications. Like how a language model learns grammar and syntax, LEONARDO learns the “grammar” of nanoparticle movement, identifying hidden reasons for the ways nanoparticles interact with their environment.
Future Impact
By simulating vast libraries of possible nanoparticle motions, LEONARDO could help train AI systems that automatically control and adjust electron microscopes for optimal imaging, paving the way for “smart” microscopes that adapt in real time, the researchers said.
“Understanding nanoscale motion is of growing importance to many fields, including drug delivery, nanomedicine, polymer science, and quantum technologies,” Jamali said. “By making it easier to interpret particle behavior, LEONARDO could help scientists design better materials, improve targeted therapies, and uncover new fundamental insights into how matter behaves at small scales.”
Read the original article on GeorgiaTech.
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NASA Discovers “Super Earth” TOI-1846 b Using TESS
NASA Discovers “Super Earth” TOI-1846 b Using TESS (Representative Image from Space)“We have validated TOI-1846 b using TESS and multicolor ground-based photometric data, high-resolution imaging, spectroscopic observations,”
NASA Discovers “Super Earth” TOI-1846 b Using TESS Latest News
The National Aeronautics and Space Administration (NASA) has confirmed the discovery of a new “Super Earth” located about 154 light-years away in the northern constellation Lyra.
In March 2025, NASA’s Transiting Exoplanet Survey Satellite (TESS) recorded a flicker of starlight. Scientists have since tracked the source of this flicker to a planet now named TOI-1846 b, a Super Earth—a type of planet larger than Earth but smaller than gas giants like Neptune.
According to reports from Earth.com, the discovery was made by Abderahmane Soubkiou and colleagues at the Oukaimeden Observatory in Morocco. NASA later confirmed the find after the research team combined TESS data with ground-based telescopic images, light measurements, and archival star photos.
What is TOI-1846 b?
TOI-1846 b is estimated to be nearly twice as wide as Earth and about four times heavier. This size-and-mass combination suggests it is denser than planets with thick, gassy atmospheres, but less dense than rocky planets like Earth. Scientists speculate it may have a layer of dense ice, a thin atmosphere, and possibly even a shallow ocean.
Despite an estimated surface temperature of around 600°F (315°C) and the likelihood that it is tidally locked (always showing the same face to its star), scientists believe water could exist in some form if these initial findings hold true.
How TESS Observes Planets
TESS, launched on April 18, 2018, scans large stripes of the sky, watching for minute dips in starlight — a sign that a planet may be transiting, or passing in front of, its host star. These dips are flagged as TESS Objects of Interest (TOIs).So far, TESS has detected over 7,600 such dips, and more than 630 of those have been confirmed as real exoplanets.
Why TOI-1846 b Stands Out
According to The Sun’s report, TESS is especially sensitive to small, cool stars, and TOI-1846, the host star of TOI-1846 b, fits that profile. The star is only about 40% the size and mass of our Sun and glows at around 6,000°F (3,300°C).This lower brightness means the star’s habitable zone—the region where liquid water could exist—is located much closer in. TOI-1846 b orbits its star in just four days, far closer than Mercury’s orbit in our solar system.
Despite the star’s dimness, TESS’s four wide-field cameras and 30-minute observational cadence allow it to detect even subtle changes in light from such distant systems.
What Scientists Say
“We have validated TOI-1846 b using TESS and multicolor ground-based photometric data, high-resolution imaging, and spectroscopic observations,” wrote Abderahmane Soubkiou in the discovery announcement.The findings have been published on arXiv, a preprint server for scientific research.
(For more news apart from “NASA Discovers “Super Earth” TOI-1846 b Using TESS,” stay tuned to Rozana Spokesman)
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Space’s Spinning Enigma: A ‘Unicorn’ Object Defies Astrophysics
Astronomers have made a groundbreaking discovery using some of the world’s most advanced radio telescopes. Researchers, led by Fengqiu Adam Dong, a Jansky Fellow at the NSF Green Bank Observatory (NSF GBO), have identified an exceptionally unusual cosmic object known as a Long Period Radio Transient (LPT), named CHIME J1634+44. This object stands out as one of the most polarized LPTs ever discovered, and it is the only one observed to be spinning up (meaning its rotation is speeding up) a phenomenon never seen before in this class of astronomical objects.
The telescopes used in this discovery include:
- U.S. National Science Foundation Green Bank Telescope (NSF GBT)
- NSF Very Large Array (NSF VLA)
- Canadian Hydrogen Intensity Mapping Experiment (CHIME) Fast Radio Burst and Pulsar Project
- NASA’s Neil Gehrels Swift Observatory (Swift)
LPTs are a newly discovered type of radio-emitting object with extremely long rotation periods, sometimes lasting minutes to hours. CHIME J1634+44’s unique properties, such as a mysterious decrease in spin period and unusual polarization, challenge the current scientific understanding and raise new questions about how these objects work and what they can teach us about the Universe.
“You could call CHIME J1634+44 a ‘unicorn’, even among other LPTs,” said Dong, noting this LPT’s particularly unusual traits. Despite hundreds of detections across multiple observatories, including those listed above, and additional observations by the LOw Frequency ARray (LOFAR) in the Netherlands, the timing of the repeating radio bursts from CHIME J1634+44 is unclear. “The bursts seem to repeat either every 14 minutes, or 841 seconds—but there is a distinct secondary period of 4206 seconds, or 70 minutes, which is exactly five times longer. We think both are real, and this is likely a system with something orbiting a neutron star,” explained Dong.
Normally, objects like neutron stars or white dwarfs slow down over time because they lose energy, so their spin period gets longer. But for CHIME J1634+44, the period is actually getting shorter—meaning it’s spinning up, not slowing down. The only way to make the timing of the bursts fit together is to assume this spin-up is real, but that doesn’t make sense for a lone star. Therefore, researchers believe that CHIME J1634+44 might actually be two stars orbiting each other very closely. If the orbit of this binary system is shrinking, it could be because they are losing energy, by emitting gravitational waves or interacting with each other, which could make it look like the period is getting shorter. This kind of shrinking orbit has been seen in other close pairs of white dwarfs. The radio bursts from CHIME J1634+44 are 100% circularly polarized, which means the radio waves twist in a perfect spiral as they travel—which is extremely rare. No known neutron star or white dwarf has ever been seen to do this for every burst. This suggests that the way these radio waves are being produced is different from what we see in all other known objects.
The unparalleled collection of telescopes used in this research allowed scientists to detect and study the object’s unusual signals in detail. CHIME’s wide field of view and daily sky scans detected the transient’s periodic bursts and monitored its spin evolution. The NSF VLA, supported by realfast (a system for real-time fast transient searches at the NSF VLA via interferometric imaging), provided high-frequency follow-up observations to mitigate interstellar medium distortions and refine localization. The NSF GBT contributed sensitive, high-resolution timing data to analyze polarization and spin-up behavior, enhancing precision for gravitational wave studies. Swift searched for X-ray counterparts, and its multi-wavelength capabilities allowed the researchers to probe for high-energy signals that complemented the radio observations from the NSF GBT, NSF VLA and CHIME. With Swift, the team was able to identify two potential X-ray sources that could be associated with the radio object.
“The discovery of CHIME J1634+44 expands the known population of LPTs and challenges existing models of neutron stars and white dwarfs, suggesting there may be many more such objects awaiting discovery,” adds Dong. This finding opens new avenues in radio astronomy and brings us a step closer to unraveling the mysteries of these enigmatic cosmic beacons.
About GBO
The Green Bank Observatory (GBO), part of the National Radio Astronomy Observatory (NRAO), are major facilities of the U.S. National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.
About CHIME
The CHIME project is co-led by the University of British Columbia, McGill University, University of Toronto, and the Dominion Radio Astrophysical Observatory with collaborating institutions across North America.
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Physicists create world’s most accurate atomic clock
By Alimat Aliyeva
Scientists at the US National Institute of Standards and
Technology (NIST) have successfully developed the most accurate
atomic clock in the world. This groundbreaking aluminum-ion-based
clock can measure time with an astonishing precision of up to 19
decimal places. The results of the research were published in
Physical Review Letters (PRL), Azernews
reports.Modern optical clocks are typically assessed on two key metrics:
accuracy, which refers to how closely the clock’s time matches the
reference time, and stability, which describes how smoothly and
consistently the clock’s ticking behaves. The new NIST clock has
proven to be not only 41% more accurate than the previous ion
clocks but also 2.6 times more stable. These results were the
product of 20 years of research and refinement, improving
everything from the lasers used to the vacuum chambers housing the
clock.The centerpiece of this breakthrough clock is the aluminum ion,
chosen for its extraordinarily stable “ticking” frequency.“Aluminum turned out to be even better than the traditional
cesium-based clocks, which form the foundation of the current
international time standard. It’s far less sensitive to
environmental factors such as temperature shifts and magnetic
fields,” explained physicist David Hume, one of the lead
researchers on the project.While aluminum’s properties were ideal for creating such an
accurate clock, the challenge was that it is notoriously difficult
to cool and synchronize with a laser. To solve this, the team added
a second ion, magnesium. Magnesium is easier to manipulate and
“assists” the aluminum by cooling it and providing feedback about
its behavior. This innovative approach is known as quantum logic
spectroscopy.“Magnesium and aluminum move in tandem, and by using magnesium,
we can accurately read the behavior of aluminum—this is how our ion
system works,” explained graduate student Willa
Arthur-Dvorshak.Achieving such unprecedented accuracy required overcoming
numerous physical obstacles. For example, the ions would
occasionally shift slightly inside the trap due to microscopic
electrical imbalances, which caused errors. This was addressed by
redesigning the electrode coating and reinforcing the trap
structure with a diamond plate to maintain stability.Another challenge emerged from the hydrogen released by the
steel walls of the vacuum chamber. When this hydrogen collided with
the ions, it disrupted the clock’s stability. To resolve this, the
researchers replaced the steel with titanium, which reduced the
hydrogen levels by a factor of 150. This modification allowed the
clock to operate continuously for several days, whereas before, it
would require reloading every half hour.“Building such a clock is incredibly fascinating. We’re working
at the frontier of fundamental physics,” said lead author Mason
Marshall, a physicist at NIST.This atomic clock could revolutionize fields that require
extreme precision, such as GPS systems, scientific experiments, and
even quantum computing. By providing a more stable and accurate
time standard, it could also improve the synchronization of data
across vast networks, making it essential for everything from
telecommunications to financial transactions.Continue Reading
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OmicsTweezer offers breakthrough in analyzing tumor microenvironments
Researchers have developed a powerful new tool that makes it easier to study the mix of cell types in human tissue, which is crucial for understanding diseases such as cancer.
Developed by researchers at Oregon Health & Science University’s Knight Cancer Institute, the tool, dubbed OmicsTweezer, uses advanced machine learning techniques to analyze biological data at a scale large enough to estimate the composition of cell types in a sample of tissue that may be taken from a biopsy. This process allows scientists to map the cellular makeup of tumors and surrounding tissues – an area known as the tumor microenvironment.
They published their findings today in Cell Genomics.
“The tumor microenvironment, made up of diverse cell types that shape tumor development and patient outcomes, has been a longstanding research priority at the Knight Cancer Institute,” said senior author Zheng Xia, Ph.D., associate professor of biomedical engineering in the OHSU School of Medicine and a member of the OHSU Knight Cancer Institute.
“Our goal is to infer cell type composition using bulk data from large clinical sample sizes.”
Usually, scientists use data from the whole tissue (called “bulk data”) and try to compare it with data from individual cells to estimate the composition of cell types. But these two types of data often don’t match because they are collected in different ways. This mismatch, called a “batch effect,” can make it hard to get accurate results.
OmicsTweezer compares known patterns from single-cell data – where researchers can study one cell at a time – with the more complex, mixed data from bulk samples. It does this by aligning both types of data in a shared digital space, making it easier to match patterns and reduce errors caused by differences in how the data was collected, leading to more reliable results.
Overcoming limits of single-cell data
While single-cell technologies can provide detailed views of individual cells, they remain expensive and technically difficult to apply to large numbers of cells within tissue samples from patients. As a result, scientists often rely on more accessible bulk data, which averages signals from many cells.
It’s still very expensive to profile a large clinical sample size using single-cell technology. But there is an abundance of bulk data – and by integrating single-cell and bulk data together, we can build a much clearer picture.”
Zheng Xia, Ph.D., associate professor of biomedical engineering, OHSU School of Medicine
Traditional tools use a simpler linear model to estimate cell types based on gene expression. But OmicsTweezer takes a more sophisticated approach, using deep learning – a branch of machine learning that finds non-linear patterns in complex data – and a method called optimal transport to align different types of data.
“We use optimal transport to align two different distributions – single-cell and bulk data – in the same space,” Xia said. “In this way, we can reduce the batch effect, which has long been a challenge when working with data from different sources.”
New possibilities in cancer research
Researchers tested OmicsTweezer on both simulated datasets and real tissue samples from patients with prostate and colon cancer. It successfully identified subtle cell subtypes and estimated cell population changes between patient groups, which could help scientists pinpoint potential therapeutic targets.
“With this tool, we can now estimate the fractions of those populations defined by single-cell data in bulk data from patient groups,” Xia said. “That could help us understand which cell populations are changing during disease progression and guide treatment decisions.”
OmicsTweezer was developed as part of a multidisciplinary collaboration at the OHSU Knight Cancer Institute, in partnership with Lisa Coussens, Ph.D., FAACR, FAIO, Gordon Mills, M.D., Ph.D., and the SMMART project. SMMART stands for Serial Measurements of Molecular and Architectural Responses to Therapy. It is the flagship project of the Knight Cancer Institute’s precision oncology program, which helps identify new treatments that last longer and improve the quality of life for patients with advanced cancer.
“This kind of work wouldn’t be possible without collaboration,” Xia said. “It really reflects the strength of the team at the Knight Cancer Institute.”
Source:
Oregon Health & Science University
Journal reference:
Yang, X., et al. (2025). OmicsTweezer: A distribution-independent cell deconvolution model for multi-omics Data. Cell Genomics. doi.org/10.1016/j.xgen.2025.100950.
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Cryo-electron microscopy – Reaction cycle of an enzyme for CO2 fixation decoded
High-resolution cryo-electron microscopy makes it possible to study complex enzymatic processes in detail. With this method, a research team of the University of Potsdam and Humboldt-Universität Berlin succeeded in characterizing the CODH/ACS enzyme complex in detail. They discovered that the complex moves in the course of chemical reactions and thus determines the reaction sequence. Their results have been published in the journal “Nature Catalysis”.
Prof. Petra Wendler and Dr. Jakob Ruickoldt when preparing the sample holder for cryo-electron microscopy.
Copyright: Sophie Reisdorf
Before the start of photosynthesis in Earth’s history and accumulation of oxygen in the atmosphere, anaerobic microorganisms lived here, which do not need oxygen for their metabolism. Anaerobic carbon fixation is considered one of the oldest and most efficient processes of its species and also plays a central role in modern ecosystems – for example in volcanic swamps or in the animal digestive tract. The enzyme complex CO-dehydrogenase-acetyl-CoA-synthase (CODH/ACS) essential for this has been preserved in microorganisms for over 3.5 billion years.
Catalysis, i.e. the acceleration of chemical processes in CODH/ACS, is based on various nickel-iron metal clusters that convert carbon dioxide into the important biomolecule acetyl-CoA in several reaction steps. The efficiency of this reaction makes CODH/ACS a promising enzyme candidate for biofuel production from carbon dioxide. Researchers from the University of Potsdam and Humboldt-Universität Berlin have now used high-resolution cryo-electron microscopy (cryo-EM) for the first time to elucidate the catalytic cycle of CODH/ACS. Cryo-EM has a wide range of applications and can be used for the structural analysis of various enzymes and biopolymers.
“Our cryo-EM maps of six intermediate states of the CODH/ACS are so highly resolved that the molecules bound to the metal center can be clearly correlated with the movements of the protein,” says Jakob Ruickoldt, first author of the study. „The different binding states of CODH/ACS have not yet been investigated using cryo-EM,” says Petra Wendler. “By using this method, we have discovered how the binding of the different molecules prepares the active center for the next reaction step and thus prevents side reactions and the loss of valuable reaction intermediates. This knowledge will help to utilize the catalysis of the ancient enzyme complex for biotechnological carbon fixation.”
Original publication
Jakob Ruickoldt, Julian Kreibich, Thomas Bick, Jae-Hun Jeoung, Benjamin R. Duffus, Silke Leimkühler, Holger Dobbek, Petra Wendler; “Ligand binding to a Ni–Fe cluster orchestrates conformational changes of the CO-dehydrogenase–acetyl-CoA synthase complex”; Nature Catalysis, 2025-7-11
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