Mosquitoes have neuronal fail-safes to make sure they can always smell humans

Mosquito on skin

When female mosquitoes are looking for a human to bite, they smell a unique cocktail of body odors that we emit into the air. These odors then stimulate receptors in the mosquitoes' antenna. Scientists have tried deleting these receptors in attempts to make humans undetectable to mosquitoes.

However, even after knocking out an entire family of odor-sensing receptors from the mosquito genome, mosquitoes still find a way to bite us. Now, a group of researchers, publishing in the journal Cell on August 18, found that mosquitoes have evolved redundant fail-safes in their olfactory system that make sure they can always smell our scents.

"Mosquitoes are breaking all of our favorite rules of how animals smell things," says Margo Herre, a scientist at Rockefeller University and one of the lead authors of the paper.

In most animals, an olfactory neuron is only responsible for detecting one type of odor. "If you're a human and you lose a single odorant receptor, all of the neurons that express that receptor will lose the ability to smell that smell," says Leslie Vosshall of the Howard Hughes Medical Institute and a professor at Rockefeller University and the senior author of the paper. But she and her colleagues found that this is not the case in mosquitoes.

"You need to work harder to break mosquitoes because getting rid of a single receptor has no effect," says Vosshall. "Any future attempts to control mosquitoes by repellents or anything else has to take into account how unbreakable their attraction is to us."

"This project really started unexpectedly when we were looking at how human odor was encoded in the mosquito brain," says Meg Younger, a professor at Boston University and one of the lead authors of the paper.

They found that neurons stimulated by the human odor 1-octen-3-ol are also stimulated by amines, another type of chemical mosquitoes use to look for humans. This is unusual since according to all existing rules of how animals smell, neurons encode odor with narrow specificity, suggesting that 1-octen-3-ol neurons should not detect amines.

"Surprisingly, the neurons for detecting humans through 1-octen-3-ol and amine receptors were not separate populations," says Younger. This may allow all human-related odors to activate "the human-detecting part" of the mosquito brain even if some of the receptors are lost, acting as a fail-safe.

The team also utilized single-nucleus RNA sequencing to see what other receptors individual mosquito olfactory neurons are expressing. "The result gave us a broad view of just how common co-expression of receptors is in mosquitoes," says Olivia Goldman, another lead author of the paper.

Vosshall thinks that other insects may have a similar mechanism. Christopher Potter's research group at Johns Hopkins University recently reported that fruit flies have similar co-expression of receptors in their neurons. "This may be a general strategy for insects that depend heavily on their sense of smell," says Vosshall.

 

How scary are spacewalks?

 TO ALEXEI LEONOV, the colours in space were much more beautiful than those on Earth. No photograph could match what the late Russian cosmonaut experienced while floating hundreds of miles above his home planet in 1965: the distant curve of blue suspended in the deep black of space; the sunset as lines of reds, greens, and yellows skimming the horizon. Other explorers have shared this otherworldly perspective, but back then no one saw it as Leonov did—from beyond the safety of a spacecraft during history’s earliest spacewalk.

With only a 16-foot tether as his lifeline, the pilot of the Voskhod 2 mission drifted alone through low Earth orbit. But after 12 minutes, awe turned to panic when his suit ballooned to the point where he couldn’t fit back through the shuttle’s airlock door. He feared that as the first to explore the vastness of space in a suit, he might also be the first to get lost in it. These days, spacewalks, also known as extravehicular activities or EVAs, are commonplace. Astronauts aboard the International Space Station (ISS) have conducted 250 of them since 1998, spending hours in the extra-terrestrial elements to install or fix scientific equipment. But even as astronauts have become more adept at roaming outside controlled environment and the technology behind their suits has improved, the risks of accidents or death remain. In Leonov’s case, the drop in atmospheric pressure caused the air in his suit to swell to dangerous proportions. If he tried to release the gas and reduce pressure, he risked bleeding off too much oxygen and asphyxiating himself. He decided to take the chance and quickly opened a valve in his suit to slim it down some, then slipped back indoors. Meanwhile, the Soviet space agency cut off a national broadcast of the mission to avoid public alarm. Leonov returned to a hero’s welcome on Earth, and it wasn’t until he shared his story that everyone realized the danger he’d faced. Since Leonov’s pioneering foray, countries have stepped up safety and training standards for spacewalks. NASA astronauts practice EVA procedures in water tanks and zero-gravity airplanes, spending nearly seven hours submerged for each hour in orbit. More recently, they’ve practiced in virtual reality. As a result, astronauts today are well prepared for EVAs, retired NASA payload commander Jeff Hoffman says. He performed four spacewalks throughout his career. His debut, in 1985, happened to be the first unplanned one in the agency’s history, when he ventured outside his shuttle to try to fix a broken satellite. “It showed how good the training [for spacewalking] was,” Hoffman said of the three-hour EVA. “I felt very comfortable, even though it was unplanned.” Equipment has improved since Leonov’s era too, enabling astronauts to trek around for longer. Almost like individual spaceships, spacesuits supply oxygen, regulate temperature, and vent exhaled carbon dioxide. Other small additions make EVAs more secure and comfortable, including devices crewmembers use to propel themselves around in short bursts, guardrails on the facades of structures that improve manoeuvrability, anti-fog coating inside helmets, and warm gloves made of many layers of insulation and tough, flexible fabric.

Still, the dangers are real. In 2013, Italian astronaut Luca Parmitano almost drowned during a spacewalk when his helmet flooded with water that had leaked earlier from the suit’s cooling system. Astronauts might also face exhaustion or blood-bubbling “bends,” caused by the same rapid pressure changes that also endanger scuba divers. Space junk, traveling at 18,000 miles per hour, poses another risk—one that Hoffman says is getting worse as stuff accumulates in Earth’s orbit. In late 2021, NASA cancelled an ISS EVA because of floating debris. Though no astronaut has been hit yet, a punctured suit could turn fatal fast. Even as spacewalks become more regular, the potential for disaster will never be fully eliminated. After all, Hoffman says, it’s part of a job that involves sitting on a loaded rocket. “I was fully confident that if anything happened that we could do something about, we’d do the right thing. And if something happened that we couldn’t do anything about—why worry?” he explains. “I took the risk because we had useful work to do.”

Risk of volcano catastrophe 'a roll of the dice'

Mount Rinjani, Indonesia

 The world is "woefully underprepared" for a massive volcanic eruption and the likely repercussions on global supply chains, climate and food, according to experts from the University of Cambridge's Centre for the Study of Existential Risk (CSER), and the University of Birmingham.

In an article published in the journal Nature, they say there is a "broad misconception" that risks of major eruptions are low, and describe current lack of governmental investment in monitoring and responding to potential volcano disasters as "reckless."

However, the researchers argue that steps can be taken to protect against volcanic devastation -- from improved surveillance to increased public education and magma manipulation -- and the resources needed to do so are long overdue.

"Data gathered from ice cores on the frequency of eruptions over deep time suggests there is a one-in-six chance of a magnitude seven explosion in the next one hundred years. That's a roll of the dice," said article co-author and CSER researcher Dr Lara Mani, an expert in global risk.

"Such gigantic eruptions have caused abrupt climate change and collapse of civilisations in the distant past."

Mani compares the risk of a giant eruption to that of a 1km-wide asteroid crashing into Earth. Such events would have similar climatic consequences, but the likelihood of a volcanic catastrophe is hundreds of times higher than the combined chances of an asteroid or comet collision.

"Hundreds of millions of dollars are pumped into asteroid threats every year, yet there is a severe lack of global financing and coordination for volcano preparedness," Mani said. "This urgently needs to change. We are completely underestimating the risk to our societies that volcanoes pose."

An eruption in Tonga in January was the largest ever instrumentally recorded. The researchers argue that if it had gone on longer, released more ash and gas, or occurred in an area full of critical infrastructure -- such as the Mediterranean -- then global shock waves could have been devastating.

"The Tonga eruption was the volcanic equivalent of an asteroid just missing the Earth, and needs to be treated as a wake-up call," said Mani.

The CSER experts cite recent research detecting the regularity of major eruptions by analysing traces of sulphur spikes in ancient ice samples. An eruption ten to a hundred times larger than the Tonga blast occurs once every 625 years -- twice as often as had been previously thought.

"The last magnitude seven eruption was in 1815 in Indonesia," said co-author Dr Mike Cassidy, a volcano expert and visiting CSER researcher, now based at the University of Birmingham.

"An estimated 100,000 people died locally, and global temperatures dropped by a degree on average, causing mass crop failures that led to famine, violent uprisings and epidemics in what was known as the year without summer," he said.

"We now live in a world with eight times the population and over forty times the level of trade. Our complex global networks could make us even more vulnerable to the shocks of a major eruption."

Financial losses from a large magnitude eruption would be in the multi-trillions, and on a comparable scale to the pandemic, say the experts.

Mani and Cassidy outline steps they say need to be taken to help forecast and manage the possibility of a planet-altering eruption, and help mitigate damage from smaller, more frequent eruptions.

These include a more accurate pinpointing of risks. We only know locations of a handful of the 97 eruptions classed as large magnitude on the "Volcano Explosivity Index" over the last 60,000 years. This means there could be dozens of dangerous volcanoes dotted the world over with the potential for extreme destruction, about which humanity has no clue.

"We may not know about even relatively recent eruptions due to a lack of research into marine and lake cores, particularly in neglected regions such as Southeast Asia," said Cassidy. "Volcanoes can lie dormant for a long time, but still be capable of sudden and extraordinary destruction."

Monitoring must be improved, say the CSER experts. Only 27% of eruptions since 1950 have had a seismometer anywhere near them, and only a third of that data again has been fed into the global database for "volcanic unrest."

"Volcanologists have been calling for a dedicated volcano-monitoring satellite for over twenty years," said Mani. "Sometimes we have to rely on the generosity of private satellite companies for rapid imagery."

The experts also call for increased research into volcano "geoengineering." This includes the need to study means of countering aerosols released by a massive eruption, which could lead to a "volcanic winter." They also say that work to investigate manipulating pockets of magma beneath active volcanoes should be undertaken.

Bioengineering: Better photosynthesis increases yields in food crops

Soybean field 

.For the first time, RIPE researchers have proven that multigene bioengineering of photosynthesis increases the yield of a major food crop in field trials. After more than a decade of working toward this goal, a collaborative team led by the University of Illinois has transgenically altered soybean plants to increase the efficiency of photosynthesis, resulting in greater yields without loss of quality.

Results of this magnitude couldn't come at a more crucial time. The most recent UN report, The State of Food Security and Nutrition in the World 2022, found that in 2021 nearly 10% of the world population was hungry, a situation that has been steadily worsening over the last few years and eclipsing all other threats to global health in scale. According to UNICEF, by 2030, more than 660 million people are expected to face food scarcity and malnutrition. Two of the major causes of this are inefficient food supply chains (access to food) and harsher growing conditions for crops due to climate change. Improving access to food and improving the sustainability of food crops in impoverished areas are the key goals of this study and the RIPE project.

Realizing Increased Photosynthetic Efficiency, or RIPE, is an international research project that aims to increase global food production by improving photosynthetic efficiency in food crops for smallholder farmers in Sub-Saharan Africa with support from the Bill & Melinda Gates Foundation, Foundation for Food & Agriculture Research, and U.K. Foreign, Commonwealth & Development Office.

"The number of people affected by food insufficiency continues to grow, and projections clearly show that there needs to be a change at the food supply level to change the trajectory," said Amanda De Souza, RIPE project research scientist, and lead author. "Our research shows an effective way to contribute to food security for the people who need it most while avoiding more land being put into production. Improving photosynthesis is a major opportunity to gain the needed jump in yield potential."

Photosynthesis, the natural process all plants use to convert sunlight into energy and yield, is a surprisingly inefficient 100+ step process that RIPE researchers have been working to improve for more than a decade. In this first-of-its-kind work, recently published in Science, the group improved the VPZ construct within the soybean plant to improve photosynthesis and then conducted field trials to see if yield would be improved as a result.

The VPZ construct contains three genes that code for proteins of the xanthophyll cycle, which is a pigment cycle that helps in the photoprotection of the plants. Once in full sunlight, this cycle is activated in the leaves to protect them from damage, allowing leaves to dissipate the excess energy. However, when the leaves are shaded (by other leaves, clouds, or the sun moving in the sky) this photoprotection needs to switch off so the leaves can continue the photosynthesis process with a reserve of sunlight. It takes several minutes for the plant to switch off the protective mechanism, costing plants valuable time that could have been used for photosynthesis.

The overexpression of the three genes from the VPZ construct accelerates the process, so every time a leaf transitions from light to shade the photoprotection switches off faster. Leaves gain extra minutes of photosynthesis which, when added up throughout the entire growing season, increases the total photosynthetic rate. This research has shown that despite achieving a more than 20% increase in yield, seed quality was not impacted.

"Despite higher yield, seed protein content was unchanged. This suggests some of the extra energy gained from improved photosynthesis was likely diverted to the nitrogen-fixing bacteria in the plant's nodules," said RIPE Director Stephen Long, Ikenberry Endowed University Chair of Crop Sciences and Plant Biology at Illinois' Carl R. Woese Institute for Genomic Biology.

The researchers first tested their idea in tobacco plants because of the ease of transforming the crop's genetics and the amount of seeds that can be produced from a single plant. These factors allow researchers to go from genetic transformation to a field trial within months. Once the concept was proven in tobacco, they moved into the more complicated task of putting the genetics into a food crop, soybeans.

"Having now shown very substantial yield increases in both tobacco and soybean, two very different crops, suggests this has universal applicability," said Long. "Our study shows that realizing yield improvements is strongly affected by the environment. It is critical to determine the repeatability of this result across environments and further improvements to ensure the environmental stability of the gain."

Additional field tests of these transgenic soybean plants are being conducted this year, with results expected in early 2023.

"The major impact of this work is to open the roads for showing that we can bioengineer photosynthesis and improve yields to increase food production in major crops," said De Souza. "It is the beginning of the confirmation that the ideas ingrained by the RIPE project are a successful means to improve yield in major food crops."

The RIPE project and its sponsors are committed to ensuring Global Access and making the project's technologies available to the farmers who need them the most.

"This has been a road of more than a quarter century for me personally," said Long. "Starting first with a theoretical analysis of theoretical efficiency of crop photosynthesis, simulation of the complete process by high-performance computation, followed by application of optimization routines that indicated several bottlenecks in the process in our crops. Funding support over the past ten years has now allowed us to engineer alleviation of some of these indicated bottlenecks and test the products at field scale. After years of trial and tribulation, it is wonderfully rewarding to see such a spectacular result for the team."

 

Seeing universe's most massive known star

 

By harnessing the capabilities of the 8.1-meter Gemini South telescope in Chile, which is part of the International Gemini Observatory operated by NSF's NOIRLab, astronomers have obtained the sharpest image ever of the star R136a1, the most massive known star in the Universe. Their research, led by NOIRLab astronomer Venu M. Kalari, challenges our understanding of the most massive stars and suggests that they may not be as massive as previously thought.

Astronomers have yet to fully understand how the most massive stars -- those more than 100 times the mass of the Sun -- are formed. One particularly challenging piece of this puzzle is obtaining observations of these giants, which typically dwell in the densely populated hearts of dust-shrouded star clusters. Giant stars also live fast and die young, burning through their fuel reserves in only a few million years. In comparison, our Sun is less than halfway through its 10 billion year lifespan. The combination of densely packed stars, relatively short lifetimes, and vast astronomical distances makes distinguishing individual massive stars in clusters a daunting technical challenge.

By pushing the capabilities of the Zorro instrument on the Gemini South telescope of the International Gemini Observatory, operated by NSF's NOIRLab, astronomers have obtained the sharpest-ever image of R136a1 -- the most massive known star. This colossal star is a member of the R136 star cluster, which lies about 160,000 light-years from Earth in the center of the Tarantula Nebula in the Large Magellanic Cloud, a dwarf companion galaxy of the Milky Way.

Previous observations suggested that R136a1 had a mass somewhere between 250 to 320 times the mass of the Sun. The new Zorro observations, however, indicate that this giant star may be only 170 to 230 times the mass of the Sun. Even with this lower estimate, R136a1 still qualifies as the most massive known star.

Astronomers are able to estimate a star's mass by comparing its observed brightness and temperature with theoretical predictions. The sharper Zorro image allowed NSF's NOIRLab astronomer Venu M. Kalari and his colleagues to more accurately separated the brightness of R136a1 from its nearby stellar companions, which led to a lower estimate of its brightness and therefore its mass.

"Our results show us that the most massive star we currently know is not as massive as we had previously thought," explained Kalari, lead author of the paper announcing this result. "This suggests that the upper limit on stellar masses may also be smaller than previously thought."

This result also has implications for the origin of elements heavier than helium in the Universe. These elements are created during the cataclysmicly explosive death of stars more than 150 times the mass of the Sun in events that astronomers refer to as pair-instability supernovae. If R136a1 is less massive than previously thought, the same could be true of other massive stars and consequently pair instability supernovae may be rarer than expected.

The star cluster hosting R136a1 has previously been observed by astronomers using the NASA/ESA Hubble Space Telescope and a variety of ground-based telescopes, but none of these telescopes could obtain images sharp enough to pick out all the individual stellar members of the nearby cluster.

Gemini South's Zorro instrument was able to surpass the resolution of previous observations by using a technique known as speckle imaging, which enables ground-based telescopes to overcome much of the blurring effect of Earth's atmosphere [1]. By taking many thousands of short-exposure images of a bright object and carefully processing the data, it is possible to cancel out almost all this blurring [2]. This approach, as well as the use of adaptive optics, can dramatically increase the resolution of ground-based telescopes, as shown by the team's sharp new Zorro observations of R136a1 [3].

"This result shows that given the right conditions an 8.1-meter telescope pushed to its limits can rival not only the Hubble Space Telescope when it comes to angular resolution, but also the James Webb Space Telescope," commented Ricardo Salinas, a co-author of this paper and the instrument scientist for Zorro. "This observation pushes the boundary of what is considered possible using speckle imaging."

"We began this work as an exploratory observation to see how well Zorro could observe this type of object," concluded Kalari. "While we urge caution when interpreting our results, our observations indicate that the most massive stars may not be as massive as once thought."

Zorro and its twin instrument `Alopeke are identical imagers mounted on the Gemini South and Gemini North telescopes, respectively. Their names are the Hawaiian and Spanish words for "fox" and represent the telescopes' respective locations on Maunakea in Hawai'i and on Cerro Pachón in Chile. These instruments are part of the Gemini Observatory's Visiting Instrument Program, which enables new science by accommodating innovative instruments and enabling exciting research. Steve B. Howell, current chair of the Gemini Observatory Board and senior research scientist at the NASA Ames Research Center in Mountain View, California, is the principal investigator on both instruments.

"Gemini South continues to enhance our understanding of the Universe, transforming astronomy as we know it. This discovery is yet another example of the scientific feats we can accomplish when we combine international collaboration, world-class infrastructure, and a stellar team," said NSF Gemini Program Officer Martin Still.

Notes

[1] The blurring effect of the atmosphere is what makes stars twinkle at night, and astronomers and engineers have devised a variety of approaches to dealing with atmospheric turbulence. As well as placing observatories at high, dry sites with stable skies, astronomers have equipped a handful of telescopes with adaptive optics systems, assemblies of computer-controlled deformable mirrors and laser guide stars that can correct for atmospheric distortion. In addition to speckle imaging, Gemini South is able to use its Gemini Multi-Conjugate Adaptive Optics System to counteract the blurring of the atmosphere.

[2] The individual observations captured by Zorro had exposure times of just 60 milliseconds, and 40,000 of these individual observations of the R136 cluster were captured over the course of 40 minutes. Each of these snapshots is so short that the atmosphere didn't have time to blur any individual exposure, and by carefully combining all 40,000 exposures the team could build up a sharp image of the cluster.

[3] When observing in the red part of the visible electromagnetic spectrum (about 832 nanometers), the Zorro instrument on Gemini South has an image resolution of about 30 milliarcseconds. This is slightly better resolution than NASA/ESA/CSA's James Webb Space Telescope and about three-times sharper resolution achieved by the Hubble Space Telescope at the same wavelength.

 

The bacteria powering a truly green revolution in personal electronics

Bacteria

Researchers at the University of Massachusetts Amherst recently announced that they have figured out how to engineer a biofilm that harvests the energy in evaporation and converts it to electricity. This biofilm, which was announced in Nature Communications, has the potential to revolutionize the world of wearable electronics, powering everything from personal medical sensors to personal electronics.

"This is a very exciting technology," says Xiaomeng Liu, graduate student in electrical and computer engineering in UMass Amherst's College of Engineering and the paper's lead author. "It is real green energy, and unlike other so-called 'green-energy' sources, its production is totally green."

That's because this biofilm -- a thin sheet of bacterial cells about the thickness of a sheet of paper -- is produced naturally by an engineered version of the bacteria Geobacter sulfurreducens. G. sulfurreducens is known to produce electricity and has been used previously in "microbial batteries" to power electrical devices. But such batteries require that G. sulfurreducens is properly cared for and fed a constant diet. By contrast, this new biofilm, which can supply as much, if not more, energy than a comparably sized battery, works, and works continuously, because it is dead. And because it's dead, it doesn't need to be fed.

"It's much more efficient," says Derek Lovley, Distinguished Professor of Microbiology at UMass Amherst and one of the paper's senior authors. "We've simplified the process of generating electricity by radically cutting back on the amount of processing needed. We sustainably grow the cells in a biofilm, and then use that agglomeration of cells. This cuts the energy inputs, makes everything simpler and widens the potential applications."

The secret behind this new biofilm is that it makes energy from the moisture on your skin. Though we daily read stories about solar power, at least 50% of the solar energy reaching the earth goes toward evaporating water. "This is a huge, untapped source of energy," says Jun Yao, professor of electrical and computer engineering at UMass, and the paper's other senior author. Since the surface of our skin is constantly moist with sweat, the biofilm can "plug-in" and convert the energy locked in evaporation into enough energy to power small devices.

"The limiting factor of wearable electronics," says Yao, "has always been the power supply. Batteries run down and have to be changed or charged. They are also bulky, heavy, and uncomfortable." But a clear, small, thin flexible biofilm that produces a continuous and steady supply of electricity and which can be worn, like a Band-Aid, as a patch applied directly to the skin, solves all these problems.

What makes this all work is that G. sulfurreducens grows in colonies that look like thin mats, and each of the individual microbes connects to its neighbors through a series of natural nanowires. The team then harvests these mats and uses a laser to etch small circuits into the films. Once the films are etched, they're sandwiched between electrodes and finally sealed in a soft, sticky, breathable polymer that you can apply directly to your skin. Once this tiny battery is "plugged in" by applying it to your body, it can power small devices.

"Our next step is to increase the size of our films to power more sophisticated skin-wearable electronics," says Yao, and Liu points out that one of the goals is to power entire electronic systems, rather than single devices.

 

Astronomers confirm star wreck as source of extreme cosmic particles

 Astronomers have long sought the launch sites for some of the highest-energy protons in our galaxy. Now a study using 12 years of data from NASA's Fermi Gamma-ray Space Telescope confirms that one supernova remnant is just such a place.

Fermi has shown that the shock waves of exploded stars boost particles to speeds comparable to that of light. Called cosmic rays, these particles mostly take the form of protons, but can include atomic nuclei and electrons. Because they all carry an electric charge, their paths become scrambled as they whisk through our galaxy's magnetic field. Since we can no longer tell which direction they originated from, this masks their birthplace. But when these particles collide with interstellar gas near the supernova remnant, they produce a tell-tale glow in gamma rays -- the highest-energy light there is.

"Theorists think the highest-energy cosmic ray protons in the Milky Way reach a million billion electron volts, or PeV energies," said Ke Fang, an assistant professor of physics at the University of Wisconsin, Madison. "The precise nature of their sources, which we call PeVatrons, has been difficult to pin down."

Trapped by chaotic magnetic fields, the particles repeatedly cross the supernova's shock wave, gaining speed and energy with each passage. Eventually, the remnant can no longer hold them, and they zip off into interstellar space.

Boosted to some 10 times the energy mustered by the world's most powerful particle accelerator, the Large Hadron Collider, PeV protons are on the cusp of escaping our galaxy altogether.

Astronomers have identified a few suspected PeVatrons, including one at the center of our galaxy. Naturally, supernova remnants top the list of candidates. Yet out of about 300 known remnants, only a few have been found to emit gamma rays with sufficiently high energies.

One particular star wreck has commanded a lot of attention from gamma-ray astronomers. Called G106.3+2.7, it's a comet-shaped cloud located about 2,600 light-years away in the constellation Cepheus. A bright pulsar caps the northern end of the supernova remnant, and astronomers think both objects formed in the same explosion.

Fermi's Large Area Telescope, its primary instrument, detected billion-electron-volt (GeV) gamma rays from within the remnant's extended tail. (For comparison, visible light's energy measures between about 2 and 3 electron volts.) The Very Energetic Radiation Imaging Telescope Array System (VERITAS) at the Fred Lawrence Whipple Observatory in southern Arizona recorded even higher-energy gamma rays from the same region. And both the High-Altitude Water Cherenkov Gamma-Ray Observatory in Mexico and the Tibet AS-Gamma Experiment in China have detected photons with energies of 100 trillion electron volts (TeV) from the area probed by Fermi and VERITAS.

"This object has been a source of considerable interest for a while now, but to crown it as a PeVatron, we have to prove it's accelerating protons," explained co-author Henrike Fleischhack at the Catholic University of America in Washington and NASA's Goddard Space Flight Center in Greenbelt, Maryland. "The catch is that electrons accelerated to a few hundred TeV can produce the same emission. Now, with the help of 12 years of Fermi data, we think we've made the case that G106.3+2.7 is indeed a PeVatron."

Bioengineered cornea can restore sight to the blind and visually impaired

Human Eye

Researchers and entrepreneurs have developed an implant made of collagen protein from pig's skin, which resembles the human cornea. In a pilot study, the implant restored vision to 20 people with diseased corneas, most of whom were blind prior to receiving the implant. The study jointly led by researchers at Linköping University (LiU) and LinkoCare Life Sciences AB has been published in Nature Biotechnology. The promising results bring hope to those suffering from corneal blindness and low vision by providing a bioengineered implant as an alternative to the transplantation of donated human corneas, which are scarce in countries where the need for them is greatest.

"The results show that it is possible to develop a biomaterial that meets all the criteria for being used as human implants, which can be mass-produced and stored up to two years and thereby reach even more people with vision problems. This gets us around the problem of shortage of donated corneal tissue and access to other treatments for eye diseases," says Neil Lagali, professor at the Department of Biomedical and Clinical Sciences at LiU, one of the researchers behind the study.

An estimated 12.7 million people around the world are blind due to their corneas, which is the outermost transparent layer of the eye, being damaged or diseased. Their only way of regaining vision is to receive a transplanted cornea from a human donor. But just one in 70 patients receives a cornea transplant. Furthermore, most of those who need cornea transplants live in low and middle-income countries in which access to treatments is very limited.

"Safety and effectiveness of the bioengineered implants have been the core of our work, says Mehrdad Rafat, the researcher and entrepreneur behind the design and development of the implants. He is an adjunct associate professor (senior lecturer) at LiU's Department of Biomedical Engineering and founder and CEO of the company LinkoCare Life Sciences AB, which manufactures the bioengineered corneas used in the study.

"We've made significant efforts to ensure that our invention will be widely available and affordable by all and not just by the wealthy. That's why this technology can be used in all parts of the world," he says.

The cornea consists mainly of the protein collagen. To create an alternative to human cornea, the researchers used collagen molecules derived from pig skin that were highly purified and produced under strict conditions for human use. The pig skin used is a byproduct of the food industry, making it easy to access and economically advantageous. In the process of constructing the implant, the researchers stabilized the loose collagen molecules forming a robust and transparent material that could withstand handling and implantation in the eye. While donated corneas must be used within two weeks, the bioengineered corneas can be stored for up to two years before use.

The researchers have also developed a new, minimally invasive method for treating the disease keratoconus, in which the cornea becomes so thin that it can lead to blindness. Today, a keratoconus patient's cornea at advanced stage is surgically removed and replaced by a donated cornea, which is sewn into place using surgical sutures. This kind of surgery is invasive and only done at larger university hospitals.

"A less invasive method could be used in more hospitals, thereby helping more people. With our method, the surgeon doesn't need to remove the patient's own tissue. Instead, a small incision is made, through which the implant is inserted into the existing cornea," says Neil Lagali, who has led the research group that has developed this surgical method.

No stitches are needed with this new surgical method. The incision in the cornea can be made with high precision thanks to an advanced laser, but also, when needed, by hand with simple surgical instruments. The method was first tested on pigs and turned out to be simpler and potentially safer than a conventional cornea transplant.

The surgical method and the implants were used by surgeons in Iran and India, two countries where many people suffer from corneal blindness and low vision, but where there is a significant lack of donated corneas and treatment options. Twenty people who were either blind or on the verge of losing sight due to advanced keratoconus participated in the pilot clinical study and received the biomaterial implant. The operations were free from complications; the tissue healed fast; and an eight-week treatment with immunosuppressive eye drops was enough to prevent rejection of the implant. With conventional cornea transplants, medicine must be taken for several years. The patients were followed for two years, and no complications were noted during that time.

The primary purpose of the pilot clinical study was to investigate whether the implant was safe to use. However, the researchers were surprised by what happened with the implant. The cornea's thickness and curvature were restored to normal. At the group level, the participants' sight improved as much as it would have after a cornea transplant with donated tissue. Before the operation, 14 of the 20 participants were blind. After two years, none of them was blind any more. Three of the Indian participants who had been blind prior to the study had perfect (20/20) vision after the operation.

A larger clinical study followed by market approval by regulatory authorities is needed before the implant can be used in healthcare. The researchers also want to study whether the technology can be used to treat more eye diseases, and whether the implant can be adapted to the individual for even greater efficacy.

Technology restores cell, organ function in pigs after death

 

Heart, concept illustration

Within minutes of the final heartbeat, a cascade of biochemical events triggered by a lack of blood flow, oxygen, and nutrients begins to destroy a body's cells and organs. But a team of Yale scientists has found that massive and permanent cellular failure doesn't have to happen so quickly.

Using a new technology they developed that delivers a specially designed cell-protective fluid to organs and tissues, the researchers restored blood circulation and other cellular functions in pigs a full hour after their deaths, they report in the Aug. 3 edition of the journal Nature.

The findings may help extend the health of human organs during surgery and expand availability of donor organs, the authors said.

"All cells do not die immediately, there is a more protracted series of events," said David Andrijevic, associate research scientist in neuroscience at Yale School of Medicine and co-lead author of the study. "It is a process in which you can intervene, stop, and restore some cellular function."

The research builds upon an earlier Yale-led project that restored circulation and certain cellular functions in the brain of a dead pig with technology dubbed BrainEx. Published in 2019, that study and the new one were led by the lab of Yale's Nenad Sestan, the Harvey and Kate Cushing Professor of Neuroscience and professor of comparative medicine, genetics, and psychiatry.

"If we were able to restore certain cellular functions in the dead brain, an organ known to be most susceptible to ischemia [inadequate blood supply], we hypothesized that something similar could also be achieved in other vital transplantable organs," Sestan said.

In the new study -- which involved senior author Sestan and colleagues Andrijevic, Zvonimir Vrselja, Taras Lysyy, and Shupei Zhang, all from Yale -- the researchers applied a modified version of BrainEx called OrganEx to the whole pig. The technology consists of a perfusion device similar to heart-lung machines -- which do the work of the heart and lungs during surgery -- and an experimental fluid containing compounds that can promote cellular health and suppress inflammation throughout the pig's body. Cardiac arrest was induced in anesthetized pigs, which were treated with OrganEx an hour after death.

Six hours after treatment with OrganEx, the scientists found that certain key cellular functions were active in many areas of the pigs' bodies -- including in the heart, liver, and kidneys -- and that some organ function had been restored. For instance, they found evidence of electrical activity in the heart, which retained the ability to contract.

"We were also able to restore circulation throughout the body, which amazed us," Sestan said.

Normally when the heart stops beating, organs begin to swell, collapsing blood vessels and blocking circulation, he said. Yet circulation was restored and organs in the deceased pigs that received OrganEx treatment appeared functional at the level of cells and tissue.

"Under the microscope, it was difficult to tell the difference between a healthy organ and one which had been treated with OrganEx technology after death," Vrselja said.

As in the 2019 experiment, the researchers also found that cellular activity in some areas of the brain had been restored, though no organized electrical activity that would indicate consciousness was detected during any part of the experiment.

The team was especially surprised to observe involuntary and spontaneous muscular movements in the head and neck areas when they evaluated the treated animals, which remained anesthetized through the entire six-hour experiment. These movements indicate the preservation of some motor functions, Sestan said.

The researchers stressed that additional studies are necessary to understand the apparently restored motor functions in the animals, and that rigorous ethical review from other scientists and bioethicists is required.

The experimental protocols for the latest study were approved by Yale's Institutional Animal Care and Use Committee and guided by an external advisory and ethics committee.

The OrganEx technology could eventually have several potential applications, the authors said. For instance, it could extend the life of organs in human patients and expand the availability of donor organs for transplant. It might also be able to help treat organs or tissue damaged by ischemia during heart attacks or strokes.

"There are numerous potential applications of this exciting new technology," said Stephen Latham, director of the Yale Interdisciplinary Center for Bioethics. "However, we need to maintain careful oversight of all future studies, particularly any that include perfusion of the brain."

Evidence that giant meteorite impacts created the continents

 

Giant impact on Earth, illustration

New Curtin research has provided the strongest evidence yet that Earth's continents were formed by giant meteorite impacts that were particularly prevalent during the first billion years or so of our planet's four-and-a-half-billion year history.

Dr Tim Johnson, from Curtin's School of Earth and Planetary Sciences, said the idea that the continents originally formed at sites of giant meteorite impacts had been around for decades, but until now there was little solid evidence to support the theory.

"By examining tiny crystals of the mineral zircon in rocks from the Pilbara Craton in Western Australia, which represents Earth's best-preserved remnant of ancient crust, we found evidence of these giant meteorite impacts," Dr Johnson said.

"Studying the composition of oxygen isotopes in these zircon crystals revealed a 'top-down' process starting with the melting of rocks near the surface and progressing deeper, consistent with the geological effect of giant meteorite impacts.

"Our research provides the first solid evidence that the processes that ultimately formed the continents began with giant meteorite impacts, similar to those responsible for the extinction of the dinosaurs, but which occurred billions of years earlier."

Dr Johnson said understanding the formation and ongoing evolution of the Earth's continents was crucial given that these landmasses host the majority of Earth's biomass, all humans and almost all of the planet's important mineral deposits.

"Not least, the continents host critical metals such as lithium, tin and nickel, commodities that are essential to the emerging green technologies needed to fulfil our obligation to mitigate climate change," Dr Johnson said.

"These mineral deposits are the end result of a process known as crustal differentiation, which began with the formation of the earliest landmasses, of which the Pilbara Craton is just one of many.

"Data related to other areas of ancient continental crust on Earth appears to show patterns similar to those recognised in Western Australia. We would like to test our findings on these ancient rocks to see if, as we suspect, our model is more widely applicable."

Plesiosaur fossils found in the Sahara suggest they weren't just marine animals

Plesiosaur illustration

Fossils of small plesiosaurs, long-necked marine reptiles from the age of dinosaurs, have been found in a 100-million year old river system that is now Morocco's Sahara Desert. This discovery suggests some species of plesiosaur, traditionally thought to be sea creatures, may have lived in freshwater.

Plesiosaurs, first found in 1823 by fossil hunter Mary Anning, were prehistoric reptiles with small heads, long necks, and four long flippers. They inspired reconstructions of the Loch Ness Monster, but unlike the monster of Lake Loch Ness, plesiosaurs were marine animals -- or were widely thought to be.

Now, scientists from the University of Bath and University of Portsmouth in the UK, and Université Hassan II in Morocco, have reported small plesiosaurs from a Cretaceous-aged river in Africa.

The fossils include bones and teeth from three-metre long adults and an arm bone from a 1.5 metre long baby. They hint that these creatures routinely lived and fed in freshwater, alongside frogs, crocodiles, turtles, fish, and the huge aquatic dinosaur Spinosaurus.

These fossils suggest the plesiosaurs were adapted to tolerate freshwater, possibly even spending their lives there, like today's river dolphins.

The new paper was headed by University of Bath Student Georgina Bunker, along with Nick Longrich from the University of Bath's Milner Centre for Evolution, David Martill and Roy Smith from the University of Portsmouth, and Samir Zouhri from the Universite Hassan II.

The fossils include vertebrae from the neck, back, and tail, shed teeth, and an arm bone from a young juvenile.

"It's scrappy stuff, but isolated bones actually tell us a lot about ancient ecosystems and animals in them. They're so much more common than skeletons, they give you more information to work with" said Dr. Nick Longrich, corresponding author on the paper.

"The bones and teeth were found scattered and in different localities, not as a skeleton. So each bone and each tooth is a different animal. We have over a dozen animals in this collection."

Whilst bones provide information on where animals died, the teeth are interesting because they were lost while the animal was alive -- so they show where the animals lived.

What's more, the teeth show heavy wear, like those fish-eating dinosaur Spinosaurus found in the same beds.

The scientists say that implies the plesiosaurs were eating the same food- chipping their teeth on the armored fish that lived in the river. This hints they spent a lot of time in the river, rather than being occasional visitors.

While marine animals like whales and dolphins wander up rivers, either to feed or because they're lost, the number of plesiosaur fossils in the river suggest that's unlikely.

A more likely possibility is that the plesiosaurs were able to tolerate fresh and salt water, like some whales, such as the beluga whale.

It's even possible that the plesiosaurs were permanent residents of the river, like modern river dolphins. The plesiosaurs' small size would have let them hunt in shallow rivers, and the fossils show an incredibly rich fish fauna.

Dr Longrich said: "We don't really know why the plesiosaurs are in freshwater.

"It's a bit controversial, but who's to say that because we paleontologists have always called them 'marine reptiles', they had to live in the sea? Lots of marine lineages invaded freshwater."

Freshwater dolphins evolved at least four times -- in the Ganges River, the Yangtze River, and twice in the Amazon. A species of freshwater seal inhabits Lake Baikal, in Siberia, so it's possible plesiosaurs adapted to freshwater as well.

The plesiosaurs belong to the family Leptocleididae- a family of small plesiosaurs often found in brackish or freshwater elsewhere in England, Africa, and Australia. And other plesiosaurs, including the long-necked elasmosaurs, turn up in brackish or fresh waters in North America and China.

Plesiosaurs were a diverse and adaptable group, and were around for more than 100 million years. Based on what they've found in Africa -- and what other scientists have found elsewhere -- the authors suggest they might have repeatedly invaded freshwater to different degrees.

"We don't really know, honestly. That's how paleontology works. People ask, how can paleontologists know anything for certain about the lives of animals that went extinct millions of years ago? The reality is, we can't always. All we can do is make educated guesses based on the information we have. We'll find more fossils. Maybe they'll confirm those guesses. Maybe not."

"It's been really interesting to see the direction this project has gone in," said lead author Georgina Bunker. The study initially began as an undergraduate project involving a single bone, but over time, more plesiosaur fossils started turning up, slowly providing a clearer picture of the animal.

The new discovery also expands the diversity of Morocco's Cretaceous. Said Dr. Samir Zouhri, "This is another sensational discovery that adds to the many discoveries we have made in the Kem Kem over the past fifteen years of work in this region of Morocco. Kem Kem was truly an incredible biodiversity hotspot in the Cretaceous."

"What amazes me" said coauthor Dave Martill, "is that the ancient Moroccan river contained so many carnivores all living alongside each other. This was no place to go for a swim."

But what does this all mean for the plausibility of something like a Loch Ness Monster? On one level, it's plausible. Plesiosaurs weren't confined to the seas, they did inhabit freshwater. But the fossil record also suggests that after almost a hundred and fifty million years, the last plesiosaurs finally died out at the same time as the dinosaurs, 66 million years ago.

Story Source: Science Daily