Category: Science

Does COVID change the body’s response to other threats? Depends on your sex, research indicates.

The long-term effects of infection on the immune system have long intrigued immunobiologist John Tsang. After the body has faced down a pathogen, does the immune system return to the previous baseline? Or does a single infection change it in ways that alter how it will respond not only to a familiar virus but also to the next new viral or bacterial threat it faces?

Tsang, a professor of immunobiology and biomedical engineering at Yale University, has long believed that the immune system reverts to the previous stable baseline after viral infection.

The emergence of the COVID-19 pandemic in 2020 allowed him and colleagues to test that theory. The answer, they find, depends on the individual’s sex, according to a study in the journal Nature.

For the study, a team led by Tsang, who at the time was at the National Institute of Allergy and Infectious Diseases (NIAID), and colleagues, including lead author Rachel Sparks, also from NIAID, systematically analyzed immune responses of healthy people who had received the flu vaccine. From that data, they then compared the responses between those who had never been infected by SARS-CoV-2, the virus that causes COVID-19, and those who experienced mild cases but recovered.

To their surprise, they found that the immune systems of men who had recovered from mild cases of COVID-19 responded more robustly to flu vaccines than women who had had mild cases or men and women who had never been infected.

In essence, the baseline immune statuses in men previously infected with SARS-CoV-2 was altered in ways that changed the response to an exposure different from SARS-CoV-2, the authors say.

“This was a total surprise,” Tsang says. “Women usually mount a stronger overall immune response to pathogens and vaccines, but are also more likely to suffer from autoimmune diseases.”

The findings may also be linked to an observation made early in the pandemic: Men were much more likely to die from a runaway immune response than women after contracting the COVID-19 virus. Even mild cases of COVID-19, the new findings suggest, might trigger stronger inflammatory responses in males than females, resulting in more pronounced functional changes to the male immune system, even long after recovery.

Their unbiased analysis of immune system status down to the individual cell level reveals several differences between COVID-recovered males and healthy controls and COVID-recovered females, both before and after receiving flu vaccinations. For instance, previously infected males produced more antibodies to influenza and produced increased levels of interferons, which are produced by cells in response to infections or vaccines. Generally, healthy females have stronger interferon responses than their male counterparts.

Understanding the lingering effects of COVID-19 on the immune system is crucial, the authors say, since more than 600 million people worldwide have been infected so far, and the emergence of “long-COVID” symptoms in some people continues to be a major health concern.

“Our findings point to the possibility that any infection or immune challenge may change the immune status to establish new set points,” says Sparks. “The immune status of an individual is likely shaped by a multitude of prior exposures and perturbations.”

Tsang thinks these findings may also help scientists create better vaccines against diverse threats by, for instance, mimicking how mild COVID-19 changes the male immune baseline.

Source: Yale University

The Oracle spacecraft will carry an optical payload made by Leidos and AFRL’s green propellant experiment for a two-year demonstration

WASHINGTON — General Atomics Electromagnetic Systems won a contract from Advanced Space to build a satellite that the Air Force Research Laboratory plans to launch to deep space in 2025.

General Atomics, based in San Diego, California, announced Jan. 5 it will produce an ESPA-class satellite bus, integrate and test payloads for Advanced Space, the prime contractor for AFRL’s Oracle experiment. 

AFRL’s Space Vehicles Directorate in November awarded Advanced Space a $72 million contract to develop a spacecraft for the Oracle mission, intended to monitor deep space, far beyond Earth’s orbit. 

The Oracle spacecraft will carry an optical payload made by Leidos and AFRL’s green propellant experiment for a two-year demonstration. 

 Oracle will seek to detect objects and demonstrate spacecraft positioning and navigation techniques far beyond geosynchronous Earth orbit, in the vicinity of Earth-moon Lagrange Point 1, about 200,000 miles from Earth. The GEO belt is about 22,000 miles above Earth.

Scott Forney, president of GA-EMS, said the platform selected for Oracle, the ESPA Grande, is a modular ring shaped bus that the company also is using to build a weather imaging satellite for the U.S. Space Force.

“The AFRL Oracle spacecraft program is intended to demonstrate advanced techniques to detect and track objects in the region near the Moon that cannot be viewed optically from the Earth or from satellites in traditional orbits,” he said in a statement.

Gregg Burgess, vice president of GA-EMS space systems, said the cislunar region “continues to be a strategic area of focus for us.” The company in 2021 won a $22 million contract from the Defense Advanced Research Projects Agency to design a small nuclear reactor for a demonstration of nuclear thermal propulsion in cislunar space.

Genetically engineered mitochondria can convert light energy into chemical energy that cells can use, ultimately extending the life of the roundworm C. elegans, a new study shows.

While the prospect of sunlight-charged cells in humans is more science fiction than science, the research, which takes a page from the field of renewable energy, sheds light on important mechanisms in the aging process.

“We know that mitochondrial dysfunction is a consequence of aging,” says Andrew Wojtovich, associate professor of anesthesiology and perioperative medicine and pharmacology and physiology at the University of Rochester Medical Center, as well as senior author of the study in Nature Aging.

“This study found that simply boosting metabolism using light-powered mitochondria gave laboratory worms longer, healthier lives. These findings and new research tools will enable us to further study mitochondria and identify new ways to treat age-related diseases and age healthier.”

Mitochondria are organelles found in most cells in the body. Often referred to as cellular power plants, mitochondria use glucose to produce adenosine triphosphate (ATP), the compound that provides energy for key functions in the cell, such as muscle contraction and the electrical impulses that help nerve cells communicate with each other.

Production of ATP is the result of a number of reactions made possible by the exchange of protons across a membrane that separates different compartments in mitochondria, the efficiency with which this occurs is called membrane potential. Known to decline with age, membrane potential is a topic of great interest in the scientific community because of its potential role in a number of age-related diseases, such as neurodegenerative disorders.

The new research involved C. elegans, a microscopic roundworm that—like the fruit fly Drosophila—has long been a research tool used by scientists to understand basic biological principles that, in many cases, apply throughout the animal kingdom.

To carry out the experiments, a team of researchers turned to optogenetics, a research tool that uses light to control biological processes within cells. Neuroscientists use optogenetics to target and activate specific neurons to study patterns of brain activity. The tool allowed the researchers to target and manipulate activity in C. elegans mitochondria—a task made easier by the fact that the worms are transparent.

The researchers genetically engineered C. elegans mitochondria to include a light-activated proton pump obtained from a fungus, an achievement the team first described in a 2020 paper in the journal EMBO Reports.

In the new study, when exposed to light, the proton pumps moved charged ions across the membrane, using the energy from the light to charge the mitochondria. This process, which the researchers dubbed mitochondria-ON (mtON), increased membrane potential and ATP production, and resulted in a 30-40% increase in lifespan of the roundworms.

“Mitochondria are similar to industrial power plants in that they combust a source of carbon, primarily glucose, to produce useful energy for the cell,” says first author Brandon Berry, who received his doctoral degree in physiology from the University of Rochester and is now a postdoctoral scholar at the University of Washington.

“What we have done is essentially hooked up a solar panel to the existing power plant infrastructure. In this instance, the solar panel is the optogenetic tool mtON. The normal mitochondrial machinery is then able to harness the light energy to provide the ATP in addition to the normal combustion pathway.”

The study is important because it provides researchers with more insight into the complex biological roles that mitochondria play in the human body, a topic that the scientific community is only now beginning to understand. The study also creates a new method to manipulate and study mitochondria in the environment of a living cell. This could serve as an important platform to study mitochondria and identify ways to intervene and support function.

“We need to understand more about how mitochondria truly behave in an animal,” says Berry. “First in worms, like the current study, but then in human cells in culture and in rodents. That way future research will be well informed to target the most likely players in human disease and aging.”

Additional coauthors are from the University of Rochester; the University of Washington; and the Research Institute for Farm Biology and Technical University of Munich, both in Germany. The National Institutes of Health and a Longevity Impetus Grant funded the work.

Source: University of Rochester

Researchers have created a map of oceanic “dead zones” that existed during the Pliocene epoch, when the Earth’s climate was two to three degrees warmer than it is now.

The work could provide a glimpse into the locations and potential impacts of future low oxygen zones in a warmer Earth’s oceans.

Oxygen minimum zones, or OMZs, are areas in the ocean where oxygen levels in the mid-waters (from 100 to 1,000 meters below the surface) are too low to support most marine life. These dead zones play an important role in the ocean’s overall health.

“OMZs are very important for geochemical cycling in the ocean,” says Catherine Davis, assistant professor of marine, earth and atmospheric sciences at North Carolina State University and corresponding author of the research in Nature Communications.

“They occur in areas where sunlight and atmospheric oxygen don’t reach. Their locations dictate where carbon and nitrogen (an essential nutrient for all life on Earth) are available in the ocean—so they’re important drivers of nutrient cycles.”

Being able to predict the location of OMZs is important not only for understanding nutrient cycling, but also because of their effects on marine life. Oceanic dead zones restrict the range of animals to the shallow surface ocean where oxygen is more plentiful.

Davis and her colleagues wanted to figure out how a warmer climate might impact future OMZs. So they looked to the Pliocene epoch, (5.3 to 2.6 million years ago) when the Earth’s atmospheric CO2 levels were close to what they are now.

“The Pliocene is the last time that we had a stable, warm climate globally, and the average global temperature was 2 C to 3 C warmer than it is now—which is what scientists predict could be the case in about 100 years,” Davis says.

To determine where Pliocene OMZs were located, the researchers used tiny fossilized plankton called foraminifera. Foraminifera are single-celled organisms about the size of a large grain of sand. They form hard, calcium carbonate shells, which can stay in marine sediments.

One species in particular—Globorotaloides hexagonus—is found only in low oxygen zones. By combing through databases of Pliocene sediments to locate that species, the team was able to map Pliocene OMZs. They overlaid their map onto a computer model of Pliocene oxygen levels, and found that the two agreed with each other.

The OMZ map shows that during the Pliocene, low-oxygen waters were much more widespread in the Atlantic Ocean—particularly in the North Atlantic. The North Pacific, on the other hand, had fewer low-oxygen areas.

“This is the first global spatial reconstruction of oxygen minimum zones in the past,” Davis says. “And it’s in line with what we’re already seeing in the Atlantic in terms of lower oxygen levels. Warmer water holds less oxygen. This dead zone map from the Pliocene could give us a glimpse into what the Atlantic might look like 100 years from now on a warmer Earth.”

What would a future with much less oxygen in the Atlantic mean? According to Davis, it could have a big impact on everything from carbon storage and nutrient cycling in the ocean to how fisheries and marine species are managed.

“OMZs act as a ‘floor’ for marine animals—they get squished to the surface,” Davis says. “So fishermen may suddenly see a lot of fish, but it doesn’t mean that there are actually more than normal—they’re just being forced into a smaller space. Fisheries will need to take the effects of OMZs into account when managing populations.

“We may also see subtle but far-reaching changes concerning the amounts of nutrients available for life in those surface waters, as well as where CO2 taken up by the ocean is stored.”

Davis began the research while a postdoctoral researcher at Yale University. Additional coauthors are from Yale, George Mason University, NASA, and NC State.

The National Science Foundation supported the work.

Source: NC State

New research on the Indian Ocean dipole shows how melting ice water from massive glaciers can ultimately lead to droughts and flooding in East Africa and Indonesia.

With a new analysis of long-term climate data, researchers say they now have a much better understanding of how climate change can cause sea water temperatures on one side of the Indian Ocean to be so much warmer or cooler than the temperatures on the other—a phenomenon that can lead to sometimes deadly weather-related events like megadroughts in East Africa and severe flooding in Indonesia.

The analysis, described in a new study in Science Advances, compares 10,000 years of past climate conditions reconstructed from different sets of geological records to simulations from an advanced climate model.

The findings show that about 18,000 to 15,000 years ago, as a result of melted freshwater from the massive glacier that once covered much of North America pouring into the North Atlantic, ocean currents that kept the Atlantic Ocean warm weakened, setting off a chain of events in response. The weakening of the system ultimately led to the strengthening of an atmospheric loop in the Indian Ocean that keeps warmer water on one side and cooler water on the other.

This extreme weather pattern, known as a dipole, prompts one side (either east or west) to have higher-than-average rainfall and the other to have widespread drought. The researchers saw examples of this pattern in both the historical data they studied and the model’s simulation. They say the findings can help scientists not only better understand the mechanisms behind the east-west dipole in the Indian Ocean, but also one day help to produce more effective forecasts of drought and flood in the region.

“We know that in the present-day gradients in the temperature of the Indian Ocean are important to rainfall and drought patterns, especially in East Africa, but it’s been challenging to show that those gradients change on long time-scales and to link them to long-term rainfall and drought patterns on both sides of the Indian Ocean,” says James Russell, a study author and professor of earth, environmental, and planetary sciences at Brown. “We now have a mechanistic basis to understand why some of the longer-term changes in rainfall patterns in the two regions have changed through time.”

Indian Ocean dipole

In the paper, the researchers explain the mechanisms behind how the Indian Ocean dipole they studied formed and the weather-related events it led to during the period they looked at, which covered the end of the last Ice Age and the start of the current geological epoch.

The researchers characterize the dipole as an east-west dipole where the water on the western side—which borders modern day East African countries like Kenya, Ethiopia, and Somalia—is cooler than the water on eastern side toward Indonesia. They saw that the warmer water conditions of the dipole brought greater rainfall to Indonesia, while the cooler water brought much drier weather to East Africa.

That fits into what is often seen in recent Indian Ocean dipole events. In October, for example, heavy rain led to floods and landslides in Indonesian islands of Java and Sulawesi, leaving four people dead and affecting over 30,000 people. On the opposite end, Ethiopia, Kenya, and Somalia experienced intense droughts starting in 2020 that threatened to cause famine.

The changes the authors observed 17,000 years ago were even more extreme, including the complete drying of Lake Victoria—one of the largest lakes on Earth.

“Essentially, the dipole intensifies dry conditions and wet conditions that could result in extreme events like multi-year or decades-long dry events in East Africa and flooding events in South Indonesia,” says Xiaojing Du, a postdoctoral researcher in the Institute at Brown for Environment and Society and Brown’s department of earth, environmental and planetary sciences, and the study’s lead author. “These are events that impact people’s lives and also agriculture in those regions. Understanding the dipole can help us better predict and better prepare for future climate change.”

The dipole the researchers studied formed from the interactions between the heat transport system of the Atlantic Ocean and an atmospheric loop, called a Walker Circulation, in the tropical Indian Ocean. The lower part of the atmospheric loop flows east to west across much of the region at low altitudes near the ocean surface, and the upper part flows west to east at higher altitudes. The higher air and lower air connect in one big loop.

Interruption and weakening of the Atlantic Ocean heat transport, which works like a conveyor belt made of ocean and wind currents, was brought on by massive melting of the Laurentide ice sheet that once covered most of Canada and the northern US. The melting cooled the Atlantic and consequent wind anomalies triggered the atmospheric loop over the tropical Indian Ocean to become more active and extreme. That then led to increased precipitation in the east side of the Indian Ocean (where Indonesia sits) and reduced precipitation in the west side, where East Africa sits.

Sea levels and melting

The researchers also show that during the period they studied, this effect was amplified by a lower sea level and the exposure of nearby continental shelves.

The scientists say more research is needed to figure out exactly what effect the exposed continental shelf and lower sea level has on the Indian Ocean’s east-west dipole, but they’re already planning to expand the work to investigate the question. While this line of the work on lower sea levels won’t play into modeling future conditions, the work they’ve done investigating how the melting of ancient glaciers impacts the Indian Ocean dipole and the heat transport system of the Atlantic Ocean may provide key insights into future changes as climate change brings about more melting.

“Greenland is currently melting so fast that it’s discharging a lot of freshwater into the North Atlantic Ocean in ways that are impacting the ocean circulation,” Russell says. “The work done here has provided a new understanding of how changes in the Atlantic Ocean circulation can impact Indian Ocean climate and through that rainfall in Africa and Indonesia.”

The study had funding from the Institute at Brown for Environment and Society and the National Science Foundation.

Source: Brown University

New images from NASA’s James Webb Space Telescope reveal for the first time galaxies with stellar bars at a time when the universe was a mere 25% of its present age.

“I took one look at these data, and I said, ‘We are dropping everything else!’”

Stellar bars are elongated features of stars stretching from the centers of galaxies into their outer disks.

The finding of so-called barred galaxies, similar to our Milky Way, this early in the universe will require astrophysicists to refine their theories of galaxy evolution.

Prior to the James Webb Space Telescope (JWST), images from the Hubble Space Telescope had never detected bars at such young epochs. In a Hubble image, one galaxy, EGS-23205, is little more than a disk-shaped smudge, but in the corresponding JWST image taken this past summer, it’s a beautiful spiral galaxy with a clear stellar bar.

“I took one look at these data, and I said, ‘We are dropping everything else!’” says Shardha Jogee, professor of astronomy at the University of Texas at Austin.

“The bars hardly visible in Hubble data just popped out in the JWST image, showing the tremendous power of JWST to see the underlying structure in galaxies,” she says, describing data from the Cosmic Evolution Early Release Science Survey (CEERS), led by UT Austin professor, Steven Finkelstein.

“It’s like going into a forest that nobody has ever gone into.”

The team identified another barred galaxy, EGS-24268, also from about 11 billion years ago, which makes two barred galaxies existing farther back in time than any previously discovered.

In an article accepted for publication in The Astrophysical Journal Letters, they highlight these two galaxies and show examples of four other barred galaxies from more than 8 billion years ago.

“For this study, we are looking at a new regime where no one had used this kind of data or done this kind of quantitative analysis before,” says Yuchen “Kay” Guo, a graduate student who led the analysis, “so everything is new. It’s like going into a forest that nobody has ever gone into.”

Bars play an important role in galaxy evolution by funneling gas into the central regions, boosting star formation.

“Bars solve the supply chain problem in galaxies,” Jogee says. “Just like we need to bring raw material from the harbor to inland factories that make new products, a bar powerfully transports gas into the central region where the gas is rapidly converted into new stars at a rate typically 10 to 100 times faster than in the rest of the galaxy.”

Bars also help to grow supermassive black holes in the centers of galaxies by channeling the gas part of the way.

The discovery of bars during such early epochs shakes up galaxy evolution scenarios in several ways.

“This discovery of early bars means galaxy evolution models now have a new pathway via bars to accelerate the production of new stars at early epochs,” Jogee says.

And the very existence of these early bars challenges theoretical models as they need to get the galaxy physics right in order to predict the correct abundance of bars. The team will be testing different models in their next papers.

JWST can unveil structures in distant galaxies better than Hubble for two reasons: First, its larger mirror gives it more light-gathering ability, allowing it to see farther and with higher resolution. Second, it can see through dust better as it observes at longer infrared wavelengths than Hubble.

Undergraduate students Eden Wise and Zilei Chen played a key role in the research by visually reviewing hundreds of galaxies, searching for those that appeared to have bars, which helped narrow the list to a few dozen for the other researchers to analyze with a more intensive mathematical approach.

Additional coauthors are from UT Austin and other institutions in the US, the UK, Japan, Spain, France, Italy, Australia, and Israel.

Funding for this research came from, in part, the Roland K. Blumberg Endowment in Astronomy, the Heising-Simons Foundation, and NASA. This work relied on resources at the Texas Advanced Computing Center.

Source: UT Austin

Researchers are using techniques from metal additive manufacturing to embed a hidden cache of information within products to help combat counterfeit goods.

Ensuring manufactured goods and components have not been copied and replaced illegally by counterfeit goods is a high-priority concern of the manufacturing and defense industries in the United States and around the world.

A potential solution could affect areas ranging from enhancing biomedical implants to protecting national defense assets.

Researchers from Texas A&M University have developed a method of imprinting a hidden magnetic tag, encoded with authentication information, within manufactured hardware during the part fabrication process. The process holds the potential to expose counterfeit goods more easily by replacing physical tags—such as barcodes or quick response (QR) codes—with these hidden magnetic tags, which serve as permanent and unique identifiers.

The team recently published its research in the journal Additive Manufacturing.

Ensuring security and reliable authentication in manufacturing is a critical national concern, with the US investing billions of dollars in manufacturing. Without such a method readily available, it can be nearly impossible to differentiate an authentic part or component from its counterfeit copy.

“The issue is that when I come up with an idea, device, or part, it is very easy for others to copy and even fabricate it much more cheaply—though maybe at a lower quality,” says Ibrahim Karaman, professor and department head of the materials science and engineering department. “Sometimes they even put the same brand name, so how do you make sure that item isn’t yours? [The embedded magnetic tag] gives us an opportunity and a new tool to make sure that we can protect our defense and manufacturing industries.”

The team is implementing metal additive manufacturing techniques to accomplish its goal of successfully embedding readable magnetic tags into metal parts without compromising performance or longevity. Researchers used 3D printing to embed these magnetic tags below the surface into nonmagnetic steel hardware.

Other applications for this method include traceability, quality control, and more, largely depending on the industry that uses it.

Once embedded into a nonmagnetic item, the magnetic tag is readable using a magnetic sensor device—such as a smartphone—by scanning near the correct location on the product.

While other methods exist for imprinting information, they primarily require sophisticated and costly equipment.

“Different approaches have been used to try to locally change the properties of the metals during the manufacturing process to be able to codify information within the part,” says Daniel Salas Mula, a researcher with the Texas A&M Engineering Experiment Station.

“This is the first time that magnetic properties of the material are being used in this way to introduce information within a nonmagnetic part, specifically for the 3D printing of metals.”

Doctoral student Deniz Ebeperi says that to map the magnetic reading of the part, the team created a custom three-axis magnetic sensor capable of mapping the surface and revealing the regions where the embedded magnetic tag was accessible.

While the system is more secure than a physical tag or code located on the exterior of an item, the team is still working to improve the complexity of the method’s security.

As the project continues, Karaman says the next steps include developing a more secure method of reading the information, possibly through the implementation of a physical “dual-authentication” requiring the user to apply a specific treatment or stimulus to unlock access to the magnetic tag.

Additional collaborators are from Texas A&M University and Purdue University. The project had support from the SecureAmerica Institute.

Source: Texas A&M University

WASHINGTON — After technical and licensing delays, Virgin Orbit is gearing up for its first launch from the United Kingdom as soon as Jan. 9.

A maritime navigation warning issued Jan. 4 identified a zone for hazardous operations for “rocket launching” off the coast of Ireland late Jan. 9, with a backup date of Jan. 18. The zone is consistent with the drop zone for Virgin Orbit’s “Start Me Up” LauncherOne mission flying out of Spaceport Cornwall in England.

Virgin Orbit spokesperson Allison Patch confirmed to SpaceNews that the navigation warning was for the upcoming launch, but said the company was not yet ready to formally announce a launch date for the mission. “All launch partners are currently working towards launch fairly soon,” she said, with a confirmation of the company’s launch plans expected in the coming days.

A separate marine notice issued by Ireland’s Department of Transport Jan. 4 listed a similar hazard area explicitly linked to the Virgin Orbit launch. In addition to the Jan. 9 and 18 launch dates, the Irish notice including potential launches on Jan. 13, 15, 19 and 20.

The hazard notices are in the event of a launch mishap involving the air-launched LauncherOne system. “Where the launch attempt proceeds as planned, no debris will enter the marine hazard area,” the Irish notice stated. “However, there is a low probability for the vehicle to produce dangerous debris if a mishap were to occur.”

Virgin Orbit had planned to conduct the Start Me Up mission last fall, flying its Boeing 747 aircraft, launch vehicle and related systems to Spaceport Cornwall in October. At one point, the company targeted a mid-December launch, only to postpone the launch days later, citing “additional technical work” on the launch system and a pending launch license from the U.K.’s Civil Aviation Authority (CAA).

The CAA awarded that launch license to Virgin Orbit Dec. 21, clearing the final regulatory hurdles for the launch. “At this time, all of Virgin Orbit’s systems are green for launch,” Dan Hart, chief executive of Virgin Orbit, said in a Dec. 22 statement. The company reported that both the vehicle and its payloads were in “good condition” to launch, but said only that a launch date would be set in the “coming weeks.”

The Start Me Up mission will place into orbit seven payloads from a variety of customers, including the U.K. Ministry of Defence, U.S. Naval Research Laboratory and the first satellite for the government of Oman.

Glassfrogs make themselves transparent while they rest by taking red blood cells from circulation and concealing them in their livers, research finds.

It’s easy to miss a glassfrog in its natural environment. The northern glassfrog, Hyalinobatrachium fleischmanni, measures no more than a few centimeters, and they are most active at night, when their green skin helps them blend in with the surrounding leaves and foliage.

But these amphibians become true masters of camouflage during the day when they’re asleep.

“When glassfrogs are resting, their muscles and skin become transparent, and their bones, eyes, and internal organs are all that’s visible,” says Carlos Taboada, a postdoctoral fellow at Duke University and a co-first author of the paper. “These frogs sleep on the bottoms of large leaves, and when they’re transparent, they can perfectly match the colors of the vegetation.”

Many animals in the sea can change the color of their skin or become completely transparent, but it’s a far less common skillset on land. One reason transparency is so difficult to achieve is because of red blood cells in the circulatory system. Red blood cells are adept at absorbing green light, which is the color of light usually reflected by plants and other vegetation. In return, these oxygen-rich cells reflect red light, making blood—and by extension the circulatory system—highly visible, especially against a bright green leaf.

Glassfrogs are some of the only land-based vertebrates that can achieve transparency, which has made them a target for study. Taboada first began studying glass frogs as a postdoctoral fellow in the lab of Sönke Johnsen, a professor of biology at Duke who specializes in studying transparency. Working with Jesse Delia, who traveled around the world collecting different glassfrogs for the study, they observed that red blood cells seemed to be disappearing from the circulating blood whenever the frogs became transparent.

They conducted additional imaging tests on the animals, proving via optical models that the animals were able to achieve transparency because they were pushing red blood cells out of their vessels. He suspected that the cells were being stored in one of the frog’s inner organs which are packaged in a reflective membrane. The finding appears in the journal Science.

For a see-through animal, its biology was shockingly challenging to decipher. The research drew on the expertise of biologists and biomedical engineers at Duke and at the American Museum of Natural History, Stanford University, and the University of Southern California.

“If these frogs are awake, stressed, or under anesthesia their circulatory system is full of red blood cells and they are opaque,” explains Delia, now a postdoctoral fellow at the American Museum of Natural History. “The only way to study transparency is if these animals are happily asleep, which is difficult to achieve in a research lab. We were really banging our heads against the wall for a solution.”

But Taboada had learned about an imaging technology called photoacoustic microscopy, or PAM, when he was studying biliverdin, the compound that gives certain species of frogs their signature green color. PAM involves shooting a safe laser beam of light into tissue, which is then absorbed by molecules and converted into ultrasonic waves. These sound waves are then used to make detailed biomedical images of the molecules. The imaging tool is non-invasive, quiet, sensitive, and, in a stroke of luck, available at Duke.

“PAM is the ideal tool for non-invasive imaging of red blood cells because you don’t need to inject contrast agents, which would be very difficult for these frogs,” explains Junjie Yao, an assistant professor of biomedical engineering at Duke who specializes in PAM technologies. “The red blood cells themselves provide the contrast, because different types of cells absorb and reflect different wavelengths of light. We could optimize our imaging systems to specifically look for red blood cells and track how much oxygen was circulating in the frog’s bodies.”

In their imaging set-up, the frogs slept upside down in a petri dish, similar to how they would sleep on a leaf, and the team shined a green laser at the animal. The red blood cells in the frog’s body absorbed the green light and emitted ultrasonic waves, which were then picked up by an acoustic sensor to trace their whereabouts, with high spatial resolution and high sensitivity.

The results were startlingly clear: When the frogs were asleep, they removed nearly 90% of their circulating red blood cells and stored them in their liver.

In further tests, the team also saw that red blood cells flowed out of the liver and circulated when the frogs were active, and then re-aggregated in the liver while the frogs were recovering.

“The primary result is that whenever glassfrogs want to be transparent, which is typically when they’re at rest and vulnerable to predation, they filter nearly all the red blood cells out of their blood and hide them in a mirror-coated liver—somehow avoiding creating a huge blood clot in the process,” says Johnsen. “Whenever the frogs need to become active again, they bring the cells back into the blood stream, which gives them the metabolic capacity to move around.”

According to Delia and Taboada, this process raises questions about how the frogs can safely store almost all their red blood cells in their liver without clotting or damaging their peripheral tissues.

One potential next step, they say, could be to study this mechanism and how it could one day apply to vascular issues in humans.

This work also introduces glassfrogs as a useful model for research, especially when paired with the state-of-the-art photoacoustic imaging. As long-time glassfrog researchers, they are excited about the new avenues of study now available to them and interested collaborators.

“We can learn more about the glassfrog’s physiology and behavior, or we can use these models to optimize imaging tools for biomedical engineering,” Delia says.

This work had support from National Geographic Society; the Human Frontier Science Program postdoctoral fellowship; the Gerstner Scholars Fellowship provided by the Gerstner Family Foundation and the Richard Gilder Graduate School at the American Museum of Natural History; start-up funds from Stanford University and start-up funds from Duke University; the National Institutes of Health; the National Science Foundation CAREER Award; the Duke Institute of Brain Science Incubator award; the American Heart Association Collaborative Sciences award; and the Chan Zuckerberg Initiative.

Source: Duke University

TAMPA, Fla. — Iridium has entered into a service provider agreement with a company widely expected to be Samsung to connect its satellites to smartphones.

The U.S.-based satellite operator said it is due to be paid royalties, development and network usage fees from the deal in a Dec. 30 regulatory filing that provided no financial details or timings.

“To protect each company’s investment in this newly developed technology, the overall arrangements include substantial recoupment payments from each company for commercializing a similar capability,” Iridium said.

The announcement comes after Iridium said in July that it had signed a development contract with a company to enable its satellite technology in smartphones. 

Iridium said both agreements are still contingent upon successfully developing the technology.

Samsung plans to use Iridium’s constellation to bring satellite connectivity to its range of Galaxy S23 range of smartphones this year, South Korean media publication ETNews reported Nov. 24.

Unlike the direct-to-smartphone service Apple launched Nov. 15 with Iridium’s rival Globalstar, ETNews said Samsung’s service would extend beyond basic SOS messaging to enable texts and low-resolution images to be sent outside terrestrial networks. 

While Iridium and South Korea-based Samsung have declined to comment on the ETNews report, Lee Seung-gwan, a senior executive at Samsung Electronics’ communications team, said a “smartphone-satellite connection is something we should pursue, obviously.”

The partnership would make sense for Iridium following Apple’s Globalstar tie-up, according to William Blair analyst Louie DiPalma, who expects the Galaxy S23 line-up to be released in February.

Globalstar’s willingness to allocate 85% of its satellite network to Apple helped seal its deal with the company behind one of the world’s most successful smartphones. 

But that level of commitment was not feasible for Iridium, DiPalma said in a note to investors Nov. 25, because thousands of blue chip customers including the U.S. Department of Defense currently rely on its network.

Even still, Iridium’s $3 billion 66-strong constellation is “considered significantly more advanced” than Globalstar’s network of 24 satellites, he said.

“In our view, the Iridium smartphone functionality will be more expansive than the Apple-GlobalStar iPhone14 partnership,” he added.

During Iridium’s latest earnings call Oct. 20, CEO Matt Desch hinted that “you can do a lot more than just push an emergency button” with a smartphone connected to a satellite. 

Apple has kept its future direct-to-smartphone plans close to its chest as it invests $450 million to upgrade Globalstar’s network.

Meanwhile, other established and startup satellite companies are preparing to offer more than just basic emergency messaging when they launch their direct-to-smartphone services in the coming years.

Texas-based AST SpaceMobile is preparing to start deploying operational satellites from late 2023 to bring 5G connectivity directly to smartphones.

Samsung Next, Samsung’s investment arm, was an early investor in AST SpaceMobile.

DiPalma expects an Iridium partnership with Samsung would contribute $20 million in revenues in its first year, although “that estimate may be conservative.”

SpaceNews correspondent Park Si-soo contributed to this story from Seoul, South Korea.