Category: 7. Science

Researchers at the Institute for Bioengineering of Catalonia (IBEC) have created the world’s simplest artificial cell capable of chemical navigation, migrating toward specific substances like living cells do. This breakthrough, published in Science Advances, demonstrates how microscopic bubbles can be programmed to follow chemical trails. The study describes the development of a ‘minimal cell’ in the form of a lipid vesicle encapsulating enzymes that can propel itself through chemotaxis.

Cellular transport is a vital aspect of many biological processes and a key milestone in evolution. Among all types of movement, chemotaxis is an essential strategy used by many living systems to move towards beneficial signals, such as nutrients, or away from harmful ones.

‘Bacteria rely on it to find food, white blood cells use it to reach sites of infection, and even sperm cells navigate towards the egg through chemotaxis,’ explains Bárbara Borges Fernandes, a PhD student in the Molecular Bionics group at IBEC, Professor at the Faculty of Physics at the University of Barcelona, and the study’s first author. ‘What we find particularly fascinating is that this type of directed movement can occur even without the complex machinery typically involved, such as flagella or intricate signalling pathways. By recreating it in a minimal synthetic system, we aim to uncover the core principles that make such movement possible.’ She adds.

Being able to engineer an artificial cell could help scientists better understand how cell units drive further evolution into more complex structures. “These synthetic cells are like blueprints for nature’s navigation system,” says senior author Professor Giuseppe Battaglia, ICREA Research Professor at IBEC, Principal Investigator of the Molecular Bionics Group and leader of the study. “Build simple, understand profoundly.”

Liposomes and pores: boats and engines

To achieve this, the research team studied how cell-like vesicles move in gradients of two substrates: glucose and urea. They enclosed glucose oxidase or urease enzymes within lipid-based vesicles, called liposomes, to convert glucose and urea into their respective end products. The liposomes were then modified by adding an essential membrane pore protein. This protein acts as a channel for substrates to enter the synthetic cell and for the products of the reactions to exit.

It is known that active motion depends on breaking symmetry. By trapping the enzymes inside the particle and utilising the pores as the primary exchange points, a difference in chemical concentration is generated around the particle. This causes fluid flow along the vesicle’s surface and directs the particle’s movement. It is as if the liposome were a boat, and the pore and the enzyme were its engine and navigation system.

From passive transport to active chemotaxis

The research team analysed the transport of over 10,000 vesicles inside microfluidic channels with glucose or urease gradients to understand general population behaviour. They studied the trajectories of vesicles with varying numbers of pores and compared them with those of control vesicles lacking pores.

‘We observe that the control vesicles move towards lower substrate concentrations due to passive effects other than chemotaxis. As the number of pores in the vesicles increases, so does the chemotactic component. Eventually, this reverses the direction of movement, causing the vesicles to move towards areas with higher substrate concentrations”, Borges explains.

These results are promising from a biochemical perspective because the elements studied are ubiquitously present in the structure of a large majority of cells.

“Watch a vesicle move. Really watch it. That tiny bubble holds secrets: how cells whisper to each other, how they ship life’s cargo. But biology’s machinery is noisy, too many parts! So, we cheat. We rebuild the whole dance with just three things: a fatty shell, one enzyme, and a pore. No fuss. Now the hidden rules jump out. That’s the power of synthetic biology: strip a puzzle down to its bones, and suddenly you see the music in the mess. What once seemed tangled? Pure, elegant chemistry, doing more with less.” describes Battaglia.

The study was conducted in collaboration with José Miguel Rubí’s team at the University of Barcelona (UB), who made the theoretical predictions. The study also benefited from the involvement of the Institute for Physics of Living Systems and the Department of Chemistry at University College London, the University of Liverpool, the Biofisika Institute (CSIC-UPV/EHU) and the Ikerbasque Foundation for Science.

Much of Earth’s ancient past lies beneath the sea. Professor Jerome Dobson of the University of Kansas coined the term “aquaterra” to describe now-submerged lands once inhabited by early humans who used them to migrate. These regions vanished as sea levels rose after the last ice age.

In collaboration with Giorgio Spada of the University of Bologna and Gaia Galassi from the University of Urbino, Dobson examined these landscapes using an advanced sea-level reconstruction model.

The researchers tracked human migration patterns between Africa and Eurasia over the past 30,000 years, focusing on coastal corridors, especially across Egypt and the Red Sea region.

Reconstructing ancient shorelines

The team’s method involved Glacial Isostatic Adjustment (GIA) models, which simulate how Earth’s crust responds to glacial melting and sea-level changes.

Using the SELEN4 model, they reconstructed ancient coastlines with accuracy, including transitions around the Mediterranean, Red Sea, and Nile Valley.

Their findings reveal that over 11 percent more land existed at the Last Glacial Maximum (LGM) than today. This exposed land formed crucial migration bridges.

Dobson emphasized, “We hope this enables people to see and explore the landscapes that were exposed during the last ice age.”

Paths early humans once traveled

Maps generated from their study reveal several alternative routes into and out of Africa.

These include a path from Foul Bay to the Nile River, the overland corridor across the Isthmus of Suez, the Gulf of Aqaba passage leading to the Levant, the Bab el-Mandeb crossing into Arabia, and the sea routes through the Sicily and Messina Straits.

Genetic analysis supports several of these paths. Wohns et al. (2022) mapped ancient DNA lineages, revealing strong ancestral roots near Meroë in Sudan. Archaeological evidence remains scarce in some areas, perhaps due to submersion.

“The early human haplotype center appears to be in northeast Sudan,” Dobson said. “That wasn’t a shock, somewhat expected by the DNA experts who discovered it. There were clear connections going up into the Levant.”

“Archaeological literature often emphasizes the southern route across the Bab el-Mandeb, but the maps they produce show little connection between the western and eastern sides of that divide.”

Lost city under the Red Sea

One striking hypothesis concerns Foul Bay on Egypt’s Red Sea coast. When sea levels were low, it could have served as a major crossing and port.

The researchers propose the existence of “Berenice Aquaterra,” a now-lost precursor to the later Greco-Roman port, Berenice Troglodytica.

The team examined historical maps. Confusion over Berenice’s location supports the idea that early humans may have seen the city shift over time due to rising seas.

Many maps from Kamal’s cartographic atlas show Berenice in multiple positions around Foul Bay.

Submerged clues in coral reefs

Foul Bay holds the world’s highest known concentration of patch coral reefs. Dobson’s surveys identified over 300 such reefs in formations that sometimes resemble human made structures.

These reefs require hard surfaces – possibly natural rock or submerged ruins – to grow.

“The unusual abundance of patch coral formations in Foul Bay raises new questions about human settlements,” the researchers wrote. Their work suggests these reefs may have grown atop stone buildings or structures lost to time.

New view of Egypt’s origins

The team also explored how these submerged routes relate to Egypt’s earliest civilizations. Settlements like Al-Badari and Naqada appear to show stronger ties with Nubia and the Red Sea coast than to Lower Egypt.

Archaeological patterns indicate a movement from Upper to Lower Egypt, challenging the idea that the Nile was settled strictly from north to south.

This supports a possible migration corridor from Foul Bay to the Nile River, bypassing the long overland Suez crossing.

Digging into the sea floor

The researchers urge underwater archaeological investigations in Foul Bay. They propose a five-step research model involving sea-level mapping, geospatial modeling, and excavation.

“We advocate urgent application of this five-step process to the Suez and Foul Bay crossings,” they concluded. This research encourages a deeper and more curious look at the ancient lands now hidden beneath the ocean.

These submerged regions, known as aquaterra, were once part of daily life for early travelers, settlers, and traders. Over time, rising sea levels erased the presence of early humans from view, leaving behind few visible traces of their stories.

Today, with improved mapping models and underwater archaeology, scientists have new ways to explore what was lost.

By studying these vanished coastlines, researchers hope to uncover how early people migrated, settled, and lived – revealing chapters of human history that have long remained out of reach.

The study is published in the journal Comptes Rendus Géoscience.

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The astronauts of SpaceX’s Crew-11 mission are making their final preparations for their July 31 trip to the International Space Station (ISS).

The four-person crew will lift off from NASA’s Kennedy Space Center in Florida, riding in the Crew Dragon Endeavour spacecraft atop a SpaceX Falcon 9 rocket on July 31, if all goes according to plan. This will be the sixth time that Endeavour has launched to space, making it SpaceX’s most-flown Crew Dragon ever.

In the era of photometry with space-based telescopes, such as CHEOPS (CHaracterizing ExOPlanets Satellite), JWST (James Webb Space Telescope), PLATO (PLAnetary Transits and Oscillations of stars), and ARIEL (Atmospheric Remote-sensing Infrared Exoplanet Large-survey), the road has opened for detecting subtle distortions in exoplanet transit light curves — resulting from their non-spherical shape.

We investigate the prospects of retrieval of rotational flatness (oblateness) of exoplanets at various noise levels. We present a novel method for calculating the transit light curves based on the Gauss-Legendre quadrature. We compare it in the non-rotating limit to the available analytical models.

We conduct injection-and-retrieval tests to assess the precision and accuracy of the retrievable oblateness values. We find that the light curve calculation technique is about 25% faster than a well-known analytical counterpart, while still being precise enough.

We show that a 3σ oblateness detection is possible for a planet orbiting bright enough stars, by exploiting a precise estimate on the stellar density obtained e.g. from asteroseismology. We also show that for noise levels ≥256 ppm (expressed as point-to-point scatter with a 60~s exposure time) detection of planetary oblateness is not reliable.

Sz. Kálmán, Sz. Csizmadia, L. M. Bernabó, R. Szabó, Gy. M. Szabó

Comments: Provisionally accepted for publication in PASP on 18/07/2025. 23 pages, 17 figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2507.15359 [astro-ph.EP] (or arXiv:2507.15359v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2507.15359
Focus to learn more
Submission history
From: Szilárd Kálmán
[v1] Mon, 21 Jul 2025 08:10:49 UTC (2,197 KB)
https://arxiv.org/abs/2507.15359
Astrobiology, exoplanet,

For hungry Neanderthals, there was more on the menu than wild mammals, roasted pigeon, seafood and plants. Chemical signatures in the ancient bones point to a nutritious and somewhat inevitable side dish: handfuls of fresh maggots.

The theory from US researchers undermines previous thinking that Neanderthals were “hypercarnivores” who stood at the top of the food chain with cave lions, sabre-toothed tigers and other beasts that consumed impressive quantities of meat.

Rather than feasting on endless mammoth steaks, they stored their kills for months, the scientists believe, favouring the fatty parts over lean meat, and the maggots that riddled the putrefying carcasses.

“Neanderthals were not hypercarnivores, their diet was different,” said John Speth, professor emeritus of anthropology at the University of Michigan. “It’s likely maggots were a major food.”

Neanderthals were thought to be top of the food chain because of the high levels of heavy nitrogen in their bones. Nitrogen builds up in living organisms when they metabolise protein in their food. A lighter form of the element, nitrogen-14, is excreted more readily than the heavier form, nitrogen-15. As a result, heavy nitrogen builds up in organisms with each step up the food chain, from plants to herbivores to carnivores.

While the levels of heavy nitrogen in Neanderthal bones place them at the top of the food chain, they would not have been able to handle the amount of meat needed to reach those levels, the researchers say.

“Humans can only tolerate up to about 4 grams of protein per kilogram of body weight, whereas animals like lions can tolerate anywhere from two to four times that much protein safely,” said Speth.

Since many Indigenous groups around the world routinely consume maggots in putrefied meat, the researchers decided to explore their potential role. The experiments were not for the squeamish.

Dr Melanie Beasley, a member of the team at Purdue University in Indiana, was formerly at the Forensic Anthropology Center, or Body Farm, at the University of Tennessee. There, researchers study donated human corpses that are left to decompose. The work helps forensic scientists hone their techniques, for example, to ascertain for how long people have been dead.

Beasley measured heavy nitrogen in putrefying muscle and the maggots that infested the corpses. Heavy nitrogen rose slightly as muscle putrefied, but was far higher in the maggots. The same process would have occurred in carcasses the Neanderthals stored, Beasley said.

The finding, reported in Science Advances, suggests that rather than consuming meat as ravenously as lions and other hypercarnivores, Neanderthals acquired high levels of heavy nitrogen by eating maggots, which themselves were enriched with heavy nitrogen.

“The only reason this is surprising is that it contradicts what we westerners think of as food,” said Karen Hardy, professor of prehistoric archaeology at the University of Glasgow. “Elsewhere in the world, a very wide range of things are eaten, and maggots are a great source of protein, fat and essential amino acids.”

“It is a no brainer for Neanderthals,” she added. “Put out a bit of meat, leave it for a few days then go back and harvest your maggots, its a very easy way to get good nutritious food.”

“How does it shift our thinking? The Neanderthals as top carnivores was nonsense, it was physiologically impossible. So this makes sense, but also explains these high nitrogen signals in a way that nothing else has done so clearly,” Hardy said.

After almost 15 years, the influential scholarly journal Science has retracted a controversial paper about the discovery of a microbe able to use arsenic instead of phosphorous in its biochemical processes (Science 2010, DOI: 10.1126/science.1197258).

In the retraction notice, H. Holden Thorp, Science’s editor in chief since 2019, states that the paper is being retracted on the basis that the “reported experiments do not support its key conclusions” but not because of any deliberate fraud or misconduct.

The retraction is accompanied by a letter from the authors disagreeing with the decision, stating, “While our work could have been written and discussed more carefully, we stand by the data as reported.”

In the original paper, the authors describe an extremophile microbe called GFAJ-1 that they believe has the ability to weave arsenic into its proteins and nucleic acids to compensate for a lack of phosphorus. Confirming that arsenic can be incorporated into DNA has the potential to expand the chemical understanding of life on Earth—and beyond, an aspect that NASA and the journal initially played up.

The paper immediately garnered harsh criticism from the scientific community over the researchers’ methods and conclusions. In 2012, Science published two papers from independent teams who were unable to replicate the original paper’s results.

The current consensus is that although GFAJ-1 is unusually good at growing in high concentrations of toxic arsenic, sufficient evidence hasn’t been found that it actually incorporates arsenic into its DNA, and the bacterium likely survives by scavenging trace phosphorus from its surroundings. The authors say in their letter that these follow-ups didn’t adequately reproduce their original growth conditions for GFAJ-1.

Back in 2012, Science’s policy was to retract papers only in cases of misconduct, which this is not. But, Thorp says, “The expectations for straightening out the literature have risen significantly,” and calls for the paper to be retracted have simmered throughout his tenure at the journal.

The tipping point was a New York Times profile of Felisa Wolfe-Simon, the paper’s outspoken first author, that was published in February 2025. Thorp went on the record in that article saying he thought the paper should be retracted.

According to guidelines from the Committee on Publication Ethics (COPE), “Retraction is a mechanism for correcting the literature and alerting readers to articles that contain such seriously flawed or erroneous content or data that their findings and conclusions cannot be relied upon. Unreliable content or data may result from honest error, naïve mistakes, or research misconduct.”

Science’s current retraction policy states, “An accumulation of errors identified in a paper may cause the editors to lose confidence in the integrity of the data presentation, and the paper may be retracted.”

Ariel Anbar of Arizona State University, one of the original paper’s authors, says the uncertainty in the data is “larger than one would like,” but “we don’t think there was a major error” that warrants retraction.

Anbar says Thorp asked Wolfe-Simon to voluntarily retract the paper last fall, after he was contacted by the New York Times. She refused. After months of negotiations, the researchers and journal editors reached a compromise: The paper would be retracted with language that both parties agreed on. The researchers could voice their dissent in a letter.

In addition to posting the retraction notice, Thorp and Science’s executive editor, Valda Vinson, published a blog post in which they expand on their reasons for retracting the paper. In the post, they reiterate that the decision is rooted in experimental error and “at no point has there been any discussion or suggestion at Science of research misconduct or fraud by any of the authors.”

Thorp says he hopes that retracting the paper will put a period on the whole affair. “I hope this is the end of it,” he says.

Anbar says he and his coauthors asked to see the blog post ahead of time, and the journal didn’t respond; they received a copy from a reporter. The post brings up critiques beyond what went into the notice, which Anbar says undermines the good-faith commitment to transparency that the authors and editors made when negotiating the retraction.

One thing both Anbar and Thorp appear to agree on—although for different reasons—is wishing that arsenic life hadn’t whipped up such a firestorm in the first place.

Astronomers have discovered key components to life’s building blocks swirling around a remote baby star, hinting that the stuff of life is far more prevalent throughout the universe than once thought.

The material, discovered circling the protostar V883 Orionis 1,300 light-years from Earth in the constellation Orion, consists of 17 complex organic molecules that include ethylene glycol and glycolonitrile — precursors to components found in DNA and RNA.