The map shows the mean production for the year 2008 across the Laurentian Great Lakes region. Lake production values are scaled from low (blue) to high (red). Image Description: A satellite image of the Great Lakes with different colors across the lakes to show lake production values. Credit: Karl Bosse/MTRI

Sixteen years of remote sensing data reveals that in Earth’s largest freshwater lakes, climate change influences carbon fixation trends.

NASA-funded research on the 11 largest freshwater lakes in the world coupled field and satellite observations to provide a new understanding of how large bodies of water fix carbon, as well as how a changing climate and lakes interact.

How Do Lakes Fix Carbon?

Phytoplankton are microscopic algae that photosynthesize, or make energy from sunlight. Carbon fixation is a part of photosynthesis — inorganic carbon (particularly carbon dioxide) is converted into an organic compound by an organism. All living things on Earth contain organic carbon. The amount of phytoplankton and the rate at which they photosynthesize equal the carbon fixation rate in a lake.

Scientists at the Michigan Tech Research Institute (MTRI) studied the five Laurentian Great Lakes bordering the U.S. and Canada; the three African Great Lakes, Tanganyika, Victoria and Malawi; Lake Baikal in Russia; and Great Bear and Great Slave lakes in Canada.

These 11 lakes hold more than 50% of the surface freshwater that millions of people and countless other creatures rely on, underscoring the importance of understanding how they are being altered by climate change and other factors.

The two Canadian lakes and Lake Tanganyika saw the greatest changes in primary productivity — the growth of algae in a water body. Productivity fluctuations point to big changes in lake ecosystems.

“The base of the food chain in these lakes is algal productivity. These lakes are oceanic in size, and are teeming with phytoplankton — small algae,” said co-author Gary Fahnenstiel, a fellow at MTRI and recently retired senior research scientist for NOAA’s Great Lakes Environmental Research Laboratory. “We measured the carbon fixation rate, which is the rate at which the algae photosynthesize in these lakes. As that rate changes, whether increasing or decreasing, it means the whole lake is changing, which has ramifications all the way up the food chain, from the zooplankton to the fish.”

Many factors affect these lakes. Climate change, increasing nutrients (eutrophication) and invasive species all combine to cause systemwide change — making it difficult to pinpoint specific causes, particularly from the ground with limited on-site observations.

Counting Phytoplankton with Color

But satellite imagery has made sorting through the noise easier and provides insights over time and space. Michael Sayers, MTRI research scientist and study lead author, uses ocean color remote sensing — making inferences about type and quantity of phytoplankton based on the color of the water — to track freshwater phytoplankton dynamics.

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p id=”caption-attachment-109254″>Annual lakewide production over the 16-year study period (2003-2018) for Lake Tanganyika, Great Bear Lake and Great Slave Lake. Each of these lakes exhibited significant changes in production over this time period, with the best fit line plotted over the annual data. Description: A line plot with three lines showing lake production trends for Lake Tanganyika (the line is trending down), Great Slave Lake (the line is trending up) and Great Bear Lake (the line is trending up). Credit: Karl Bosse/MTRI

“We’ve relied on NASA assets — the MODIS satellite, which has been flying since 2002, to which we apply the algorithm and model we’ve been developing at MTRI for a decade,” Sayers said. “When we start to tally the numbers of pixels as observations globally for 11 lakes for 16 years, it is really quite remarkable.” The pixels observed per lake number “in the millions,” he added. 

One of the most remarkable aspects of the results is just how fast changes in these freshwater lakes have occurred — a noticeable amount in fewer than 20 years. The research contributes to NASA’s Carbon Monitoring System’s goal of determining how much freshwater lakes contribute to the global carbon cycle.

“Three of the largest lakes in the world are showing major changes related to climate change, with a 20-25% change in overall biological productivity in just the past 16 years,” Fahnenstiel said.

More Than Algae

In the 16 years of data, Great Bear and Great Slave lakes in northern Canada saw the greatest increases in productivity, while Lake Tanganyika in southeastern Africa has seen decreases. The trends are linked to increases in water temperatures, as well as solar radiation and a reduction in wind speed.

Sayers said looking at productivity, algal abundance, water clarity, water temperature, solar radiation and wind speeds at freshwater lakes provides a richer picture of the overall ecosystem.

“Temperature and solar radiation are factors of climate change,” Sayers said. “Chlorophyll and water transparency changes are not necessarily caused by climate change, but could be caused by eutrophication or invasive species, like quagga mussels.”

The researchers used lake measurements performed by the Great Lakes Research Center research vessel fleet to ground truth the satellite observations and to provide input for model estimates.

The article “Carbon Fixation Trends in Eleven of the World’s Largest Lakes: 2003–2018” is published in the journal Water. The researchers plan to continue their research, applying what they’ve learned so far to the role harmful algal blooms have on carbon flux to the atmosphere.

As the saying goes, water is life. Gaining a better understanding of how lake productivity changes affect the bodies of water so many people rely on is important to the communities who live on the lakeshores. It’s also significant to the global community as we delve deeper into the role freshwater lakes play in the global carbon cycle and climate change.

Reference: “Carbon Fixation Trends in Eleven of the World’s Largest Lakes: 2003–2018” by Michael Sayers, Karl Bosse, Gary Fahnenstiel and Robert Shuchman, 12 December 2020, Water.
DOI: 10.3390/w12123500

Deep Space Station 56, or DSS-56, is a powerful 34-meter-wide (112-foot-wide) antenna that was added to the Deep Space Network’s Madrid Deep Space Communications Complex in Spain in early 2021. Credit: NASA/JPL-Caltech

The addition brings new capabilities to the network, which acts as an interplanetary switchboard, connecting us to missions at the Moon and far beyond.

A powerful new antenna has been added to the NASA Space Communications and Navigation’s Deep Space Network (DSN), which connects us to the space robots exploring our solar system. Called Deep Space Station 56, or DSS-56, the dish is now online and ready to communicate with a variety of missions, including NASA’s Perseverance rover when it lands on the Red Planet next month.

The new 34-meter-wide (112-foot-wide) dish has been under construction at the Madrid Deep Space Communications Complex in Spain since 2017. Existing antennas are limited in the frequency bands they can receive and transmit, often restricting them to communicating only with specific spacecraft. DSS-56 is the first to use the Deep Space Network’s full range of communication frequencies as soon as it went online. This means DSS-56 is an “all-in-one” antenna that can communicate with all the missions that the DSN supports and can be used as a backup for any of the Madrid complex’s other antennas.

“DSS-56 offers the Deep Space Network additional real-time flexibility and reliability,” said Badri Younes, deputy associate administrator and program manager of NASA’s Space Communications and Navigation (SCaN). “This new asset symbolizes and underscores our ongoing support for more than 30 deep space missions who count on our services to enable their success.”

You can check in on the which spacecraft the Deep Space Network’s antennas are currently communicating with via the online application DSN Now. Click on a dish to learn more about the live connection between the spacecraft and the ground.

With the addition of DSS-56 and other 34-meter antennas to all three DSN complexes around the world, the network is preparing to play a critical role in ensuring communication and navigation support for upcoming Moon and Mars missions and the crewed Artemis missions.

Three eye-catching posters featuring the larger 70-meter (230-feet) antennas located at the three Deep Space Network complexes around the world are available for download here. Credit: NASA/JPL-Caltech

“The Deep Space Network is vital to so much of what we do – and to what we plan to do – throughout the solar system. It’s what connects us here on Earth to our distant robotic explorers, and, with the improvements that we’re making to the network, it connects us to the future as well, expanding our capabilities as we prepare human missions for the Moon and beyond,” said Thomas Zurbuchen, associate administrator of the Science Mission Directorate at NASA’s headquarters in Washington. “This latest antenna was built as an international partnership and will ultimately benefit all of humanity as we continue to explore deep space.”

With DSS-56’s increased flexibility came a more complex start-up phase, which included testing and calibration of a larger suite of systems, before the antenna could go online. On Friday, January 22, the international partners who oversaw the antenna’s construction attended a virtual ribbon-cutting event to officially mark the occasion – an event that had been delayed due to historic snowfall blanketing much of Spain.

“After the lengthy process of commissioning, the DSN’s most capable 34-meter antenna is now talking with our spacecraft,” said Bradford Arnold, DSN project manager at NASA’s Jet Propulsion Laboratory in Southern California. “Even though pandemic restrictions and the recent weather conditions in Spain have been significant challenges, the staff in Madrid persevered, and I am proud to welcome DSS-56 to the global DSN family.”

More About the Deep Space Network

In addition to Spain, the Deep Space Network has ground stations in California (Goldstone) and Australia (Canberra). This configuration allows mission controllers to communicate with spacecraft throughout the solar system at all times during Earth’s rotation.

The forerunner to the DSN was established in January 1958 when JPL was contracted by the U.S. Army to deploy portable radio tracking stations in California, Nigeria, and Singapore to receive telemetry of the first successful U.S. satellite, Explorer 1. Shortly after JPL was transferred to NASA on Dec. 3, 1958, the newly-formed U.S. civilian space program established the Deep Space Network to communicate with all deep space missions. It has been in continuous operation since 1963 and remains the backbone of deep space communications for NASA and international missions, supporting historic events such as the Apollo Moon landings and checking in on our interstellar explorers, Voyager 1 and 2.

The Deep Space Network is managed by JPL for SCaN, which is located at NASA’s headquarters within the Human Exploration and Operations Mission Directorate. The Madrid station is managed on NASA’s behalf by Spain’s national research organization, Instituto Nacional de Técnica Aeroespacial (National Institute of Aerospace Technology).

Research shows people with a high omega-3 index less are likely to die from COVID-19.

Researchers with the Fatty Acid Research Institute (FARI) and collaborators at Cedars-Sinai Medical Center in Los Angeles and in Orange County, CA, have published the first direct evidence that higher omega-3 blood levels may reduce risk for death from COVID-19 infection. The report was published in the journal Prostaglandins, Leukotrienes and Essential Fatty Acids on January 20, 2021.

There are several papers in the medical literature hypothesizing that omega-3 fatty acids should have beneficial effects in patients with COVID-19 infection, but up until now, there have been no published peer-reviewed studies supporting that hypothesis.

This study included 100 patients admitted to the hospital with COVID-19 for whom admission blood samples had been stored. Clinical outcomes for these patients were obtained and blood was analyzed for the Omega-3 Index (O3I, red blood cell membrane EPA+DHA levels) at OmegaQuant Analytics (Sioux Falls, SD). Fourteen of the patients died.

The 100 patients were grouped into four quartiles according to their O3I, with 25% of the patients in each quartile. There was one death in the top quartile (i.e., 1 death out of 25 patients with O3I>5.7%), with 13 deaths in the remaining patients (i.e., 13 deaths out of 75 patients with O3I<5.7%).

In age-and-sex adjusted regression analyses, those in the highest quartile (O3I >5.7%) were 75% less likely to die compared with those in the lower three quartiles (p=0.07). Stated another way, the relative risk for death was about four times higher in those with a lower O3I (<5.7%) compared to those with higher levels.

“While not meeting standard statistical significance thresholds, this pilot study – along with multiple lines of evidence regarding the anti-inflammatory effects of EPA and DHA – strongly suggests that these nutritionally available marine fatty acids may help reduce risk for adverse outcomes in COVID-19 patients. Larger studies are clearly needed to confirm these preliminary findings,” said Arash Asher, MD, the lead author on this study.

Agreeing with Dr. Asher, cardiology researcher and co-developer with Dr. Harris of the Omega-3 Index, Clemens von Schacky, MD, (CEO, Omegametrix GmbH, Martinsried, Germany, and not involved with the study) said, “Asher et al have demonstrated that a low Omega-3 Index might be a powerful predictor for death from COVID-19. Although encouraging, their findings clearly need to be replicated.”

Omega-3 expert James H. O’Keefe, Jr., MD, (Director of Preventive Cardiology, Saint Luke’s Mid America Heart Institute, Kansas City, MO, and also not involved with the study) observed, “An excessive inflammatory response, referred to as a ‘cytokine storm,’ is a fundamental mediator of severe COVID-19 illness. Omega-3 fatty acids (DHA and EPA) have potent anti-inflammatory activities, and this pilot study provides suggestive evidence that these fatty acids may dampen COVID-19’s cytokine storm.”

The FARI research team is currently seeking funding to expand upon these preliminary observations. Individuals and organizations that want to support this research are encouraged to visit FARI’s donations page.

Reference: “Blood omega-3 fatty acids and death from COVID-19: A Pilot Study” by Arash Asher, Nathan L. Tintle, Michael Myers, Laura Lockshon, Heribert Bacareza and William S. Harris, 20 January 2021, Prostaglandins, Leukotrienes and Essential Fatty Acids.
DOI: 10.1016/j.plefa.2021.102250

The Fatty Acid Research Institute (FARI) is a non-profit research and education foundation. FARI was founded in order to accelerate discovery of the health effects of fatty acids, most notably, the long chain omega-3 fatty acids EPA and DHA. FARI researchers and scientists will focus single-mindedly on publishing high-quality research studies on the multiple relationships between fatty acid levels and human (and animal) health outcomes. These studies will improve the ability to predict risk for disease, and more importantly, suggest ways to reduce risk by changing our diets and/or supplementation regimens.

Life reconstruction of a Spinosaurus wading in the water and fishing. Credit: Image by Robert Nicholls

New research from Queen Mary University of London and the University of Maryland, has reignited the debate around the behavior of the giant dinosaur Spinosaurus.

Since its discovery in 1915, the biology and behavior of the enormous Spinosaurus has puzzled paleontologists worldwide. It was recently argued that the dinosaur was largely an aquatic predator, using its large tail to swim and actively pursue fish in the water.

The new study, published today in Palaeontologia Electronica, challenges this recent view of Spinosaurus suggesting that whilst it likely fed from the water, and may have swum, it wasn’t well adapted to the life of an aquatic pursuit predator. Instead it was like a giant (if flightless) heron or stork — snatching at fish from the shoreline while also taking any other small available prey on land or in water.

The researchers compared the features of Spinosaurus with the skulls and skeletons of other dinosaurs and various living and extinct reptiles that lived on land, in the water or did both. They found that whilst there were several pieces of evidence that contradicted the aquatic pursuit predator concept, none contradicted the wading heron-like model, and various lines of evidence actively supported it.

Reconstructed skeleton of a moderately sized Spinosaurus showing its famous sail-back and tail plume. Scale bar is 1 m. Credit: Image by Genya Masukawa

Dr. David Hone, Senior Lecturer at Queen Mary and lead author on the project said: “The biology and ecology of Spinosaurus has been troubling paleontologists for decades. Some recent studies have suggested that it was actively chasing fish in water but while they could swim, they would not have been fast or efficient enough to do this effectively. Our findings suggest that the wading idea is much better supported, even if it is slightly less exciting.”

Co-author Tom Holtz, Principal Lecturer in Vertebrae Paleontology, University of Maryland, said: “Spinosaurus was a bizarre animal even by dinosaur standards, and unlike anything alive today, so trying to understand its ecology will always be difficult. We sought to use what evidence we have to best approximate its way of life. And what we found did not match the attributes one would expect in an aquatic pursuit predator in the manner of an otter, sea lion, or short-necked plesiosaur.”

One of the key pieces of evidence unearthed by the researchers related to the dinosaur’s ability to swim. Spinosaurus was already shown to be a less efficient swimmer than a crocodile, but also has fewer tail muscles than a crocodile, and due to its size would have a lot more drag in the water.

Saddle-billed storks in Africa foraging with their beaks partly below water – Spinosaurus may have done something similar. Credit: Photograph by David Hone

Dr. Hone said: “Crocodiles are excellent in water compared to land animals, but are not that specialized for aquatic life and are not able to actively chase after fish. If Spinosaurus had fewer muscles on the tail, less efficiency and more drag then it’s hard to see how these dinosaurs could be chasing fish in a way that crocodiles cannot.”

Dr. Holtz added: “We certainly add that the evidence points to Spinosaurus feeding partly, even mostly, in the water, probably more so than any other large dinosaur. But that is a different claim than it being a rapid swimmer chasing after aquatic prey.” Though as Dr. Hone concludes: “Whilst our study provides us with a clearer picture of the ecology and behavior of Spinosaurus, there are still many outstanding questions and details to examine for future study and we must continue to review our ideas as we accumulate further evidence and data on these unique dinosaurs. This won’t be the last word on the biology of these amazing animals.”

Originally found in Egypt, Spinosaurus is thought to be one of the largest carnivorous dinosaurs to exist probably reaching over 15 m in length. The first known Spinosaurus fossils were destroyed by Allied bombing during World War II, which has hampered paleontologist’s attempts to understand these unusual creatures. More recently the dinosaur found fame in the 2001 film Jurassic Park III, where it battles and defeats a Tyrannosaurus rex.

Reference: “Evaluating the ecology of Spinosaurus: Shoreline generalist or aquatic pursuit specialist?” by David W.E. Hone and Thomas R. Holtz, Jr., January 2021, Palaeontologia Electronica.
DOI: 10.26879/1110

A new test quickly and easily identifies when sperm are carrying chromosomal mutations, and could be applied for men hoping to have children.

Chemotherapy and radiation treatments are known to cause harsh side effects that patients can see or feel throughout their bodies. Yet there are additional, unseen and often undiscussed consequences of these important therapies: the impacts on their future pregnancies and hopes for healthy children.

Extensive evidence shows that chemotherapy and radiation treatments are genotoxic, meaning they can mutate the DNA and damage chromosomes in patients’ cancerous and noncancerous cells alike. When this occurs in a germline cell – which are egg cells in women and sperm in men – it can lead to serious fetal and birth defects in a resulting pregnancy. For the few chemotherapies that have been studied, the risk of mutated sperm diminishes over time, as the treatment agents leave the body and men produce new sperm that were never exposed to the genotoxic agents. But for most chemotherapeutic drugs, there is still no information on their impact on DNA mutations and chromosomal damage to human sperm.

Human sperm stained for semen quality testing in the clinical laboratory. Credit: Bobjgalindo/Wikimedia

Exacerbating the problem, there are currently no efficient and affordable tests that can be used to track men’s germ cell health by identifying when the sperm are carrying treatment-related chromosomal mutations such as aneuploidy (abnormal number of chromosomes) or chromosome breaks, rearrangements, or deletions. But evidence from a new study led by Andrew Wyrobek at the Lawrence Livermore National Laboratory, and now at the Lawrence Berkeley National Laboratory (Berkeley Lab), suggests that this may soon change.

In a paper published in the journal PLOS One, the international team reported success adapting an established cellular DNA analysis technique called fluorescence in situ hybridization (FISH) to probe sperm DNA for a wide variety of chromosomal defects simultaneously. This version of the FISH technique, known as the AM8 sperm FISH protocol, is the result of decades of work done by the research team of lead author Andrew Wyrobek. A medical biophysicist at Berkeley Lab, Wyrobek studies the effects of ionizing radiation and human-made chemicals on breast cancer, brain function, and male reproductive health.

“This work is the first demonstration that our sperm assay can simultaneously measure aneuploidy and other chromosomal aberrations in sperm from men who have undergone genotoxic treatments,” said Wyrobek. “When sperm with these chromosomal abnormalities fertilize an egg, the resulting fetus and live-born child may have severe health issues. For example, fetuses with trisomy 18 – an extra copy of chromosome 18 or a fetus with an unbalanced chromosomal rearrangement – typically die in utero or within a year of birth.”

And, most importantly, according to Wyrobek, the assay can detect balanced chromosomal abnormalities, which are rearrangement with no loss or gain of genetic material. Balanced rearrangements are compatible with live birth and heritable to future pregnancies, and affected children are likely to experience reduced fertility when they want to have children of their own.

The team – which included scientists from Lawrence Livermore National Laboratory, Stanford University, MD Anderson Cancer Center, and the National Autonomous University of Mexico – evaluated the AM8 FISH approach on sperm from nine Hodgkin lymphoma patients, who provided samples before, during, and after a multi-drug treatment regimen and radiation therapy.

Results from the FISH protocol tests indicated that sperm produced during the Hodgkin lymphoma treatment had 10 times more chromosomal defects compared with sperm produced prior to treatment. But by month six post-treatment, the patients’ sperm had returned to pre-treatment quality.

“We are excited by these results because they are a first step toward applying this method to any human situation – such as aging, illness, drugs, or exposure to environmental toxicants – to determine genetic risks to male germ cells and to examine the persistence of chromosomally damaged sperm,” said Wyrobek. “We believe this approach has a wide range of applications in healthcare and family planning, as it can be used to identify environmental exposures that increase the risk for producing chromosomally abnormal sperm that can affect the health of future pregnancies and children for generations to come.”

However, according to Wryobek, the sperm FISH method is still in an early research phase and it will require additional validation and commercial development before it becomes available in doctor’s offices.

Reference: “Meiotic susceptibility for induction of sperm with chromosomal aberrations in patients receiving combination chemotherapy for Hodgkin lymphoma” by Sara Frias, Paul Van Hummelen, Marvin L. Meistrich and Andrew J. Wyrobek, 28 December 2020, PLOS ONE.
DOI: 10.1371/journal.pone.0242218

This work was supported by the National Institute of Environmental Health Science and the authors’ respective institutions.

The sweet taste of sugar, energy intake and the regulatory process of hunger and satiety.

The sweet taste of sugar is very popular worldwide. In Austria and Germany, the yearly intake per person adds up to about 33 and 34 kilograms, respectively. Thus, sugar plays an increasingly role in the nutrition and health of the population, especially with regard to body weight. However, little is known about the molecular (taste) mechanisms of sugar that influence dietary intake, independently of its caloric load.

Taste receptor and satiety regulation

“We therefore investigated the role of sweet taste receptor activation in the regulation of satiety,” says Veronika Somoza, deputy head of the Department of Physiological Chemistry at the University of Vienna and director of the Leibniz Institute for Food Systems Biology at the Technical University of Munich.

For this purpose, the scientists conducted a blinded, cross-over intervention study with glucose and sucrose. A total of 27 healthy, male persons, between 18 and 45 years of age, received either a 10 percent glucose or sucrose solution (weight percent) or one of the sugar solutions supplemented with 60 ppm lactisole. Lactisole is a substance that binds to a subunit of the sweet receptor and reduces the perception of sweet taste. Despite different types of sugar, all solutions with or without lactisole had the same energy content.

Two hours after drinking each of the test solutions, the participants were allowed to have as much as breakfast they wanted. Shortly before and during the 120-min waiting period, the researchers took blood samples in regular intervals and measured their body temperature.

Additional 100 kilocalories on average

After the consumption of the lactisole-containing sucrose solution, the test persons had an increased energy intake from breakfast of about 13 percent, about 100 kilocalories more, than after drinking the sucrose solution without lactisole. In addition, the subjects of this group showed lower body temperature and reduced plasma serotonin concentrations. Serotonin is a neurotransmitter and tissue hormone which, among other things, has an appetite-suppressing effect. In contrast, the researchers observed no differences after administration of the lactisole-containing glucose solution and the pure glucose solution.

“This result suggests that sucrose, regardless of its energy content, modulates the regulation of satiety and energy intake via the sweet taste receptor,” says Barbara Lieder, head of Christian Doppler Laboratory for Taste Research and also deputy head of the Department of Physiological Chemistry of the Faculty of Chemistry at University of Vienna.

The first study author of the study, Kerstin Schweiger, University of Vienna adds: “We do not know yet why we could not observe the lactisole effect with glucose. However, we suspect it is because glucose and sucrose activate the sweet receptor in different ways. We also assume that mechanisms independent of the sweet receptor play a role.”

“So there is still a lot of research needed to clarify the complex relationships between sugar consumption, taste receptors and satiety regulation on the molecular level,” says Veronika Somoza. In particular, as sweet receptors are also found in the digestive tract and little is known about their function there. The first steps have nevertheless been taken.

Reference: “Sweet Taste Antagonist Lactisole Administered in Combination with Sucrose, But Not Glucose, Increases Energy Intake and Decreases Peripheral Serotonin in Male Subjects” by Kerstin Schweiger, Verena Grüneis, Julia Treml, Claudia Galassi, Corinna M. Karl, Jakob P. Ley, Gerhard E. Krammer, Barbara Lieder and Veronika Somoza, 14 October 2020, Nutrients.
DOI: 10.3390/nu12103133

A recent study focusing on “the L.A. megacity” — an area encompassing all of Los Angeles County and areas beyond — found that urban greenery added a small unexpected amount to the region’s overall output of carbon dioxide.
Credit: Michael Bogner

A new study tracing the sources of carbon dioxide, the most significant human-generated greenhouse gas, reveals the unexpectedly large influence of vegetation in urban environments.

Burning fossil fuels in densely populated regions greatly increases the level of the greenhouse gas, carbon dioxide. The largest carbon dioxide sources are cars, trucks, ports, power generation, and industry, including manufacturing. Urban greenery adds CO2 to the atmosphere when vegetation dies and decomposes, increasing total emissions. Urban vegetation also removes this gas from the atmosphere when it photosynthesizes, causing total measured emissions to drop. Understanding the role of urban vegetation is important for managing cities’ green spaces and tracking the effects of other carbon sources.

A recently published study showed that among the overall sources of carbon dioxide in urban environments, a fraction is from decaying trees, lawns, and other urban vegetation. The contribution is modest — about one-fifth of the measured CO2 contributed by the urban environment — and varies seasonally. This was more than researchers anticipated and underscores the complexity of tracking urban carbon emissions.

The team behind the study made this discovery by tracing carbon dioxide sources with carbon-14, a rare form of carbon that occurs naturally in Earth’s atmosphere and is absorbed by living things as they grow. Carbon-14’s presence in organic materials is the basis of radiocarbon dating and serves as a powerful tool to distinguish the carbon dioxide produced by fossil fuel combustion from that produced by decomposing vegetation and other organic matter. The carbon found in coal, oil, and natural gas is hundreds of millions of years old; all of its carbon-14 decayed long ago.

The researchers measured levels of “excess” carbon dioxide, or the amount that’s above what can be attributed to natural, background sources. Focusing on the “Los Angeles megacity” — a multicity region encompassing nearly 6,000 square miles (15,000 square kilometers) and 18 million people — they found that, over the course of a year, urban greenery accounts for about one-fifth of the excess carbon dioxide observed in the air over the study area. There were additional, small contributions from biofuels, such as ethanol, and from human metabolism.

The team included scientists from the National Oceanic and Atmospheric Administration (NOAA), NASA’s Jet Propulsion Laboratory, and the University of Colorado. The measurements were performed on air samples collected from late 2014 to early 2016, using air-sampling devices placed in three sites across the L.A. basin.

“Before we started the experiment, we thought we were going to see almost all anthropogenic [human-caused] emissions, given the volume of traffic in L.A.,” said study co-author Charles Miller, a research scientist at JPL. “We were able to find out it wasn’t all due to fossil fuel combustion.”

While the finding in Southern California was a surprise, the contribution from urban greenery might be even more pronounced in many cities of the tropics.

“In the tropics and subtropics — those places where vegetation grows like crazy and there are high rates of decomposition — you might find much larger fractions,” Miller added. “Without the vegetation component factored into estimates [for total emissions], we will systematically overestimate fossil fuel emissions. This is important to those responsible for both reporting and mitigation.”

The study is part of a larger, years-long effort involving a variety of researchers called the “Megacities Carbon Project.” It shows the importance of managing carbon in cities from a “holistic” point of view, said study co-author Riley Duren, now a researcher at the University of Arizona and a JPL engineering fellow.

“Understanding these relationships can help planners design and manage green spaces in ways that pull as much carbon out of the atmosphere as possible and store it permanently while minimizing the release of emissions of CO2 from plants as they dry out or during non-growing seasons, ideally with native, drought-tolerant species,” Duren added.

Another Kind of Carbon

Carbon-14 is mainly created by gamma rays from the Sun in Earth’s upper atmosphere, where it becomes chemically incorporated into carbon dioxide. It is transported by winds downward toward Earth’s surface and then around the planet.

Living organisms absorb carbon dioxide that contains both “regular” carbon (carbon-12) and carbon-14. Once an organism dies, the carbon-14, which is radioactive, decays away over time. Through radiocarbon dating, scientists have long used carbon-14 as a natural “clock” for estimating the age of dead plants and animals as well as the age of materials made from them — for instance, fragments of antique woolen blankets or the dregs of wine in the bottom of ancient urns.

“Fossil fuel carbon buried in the ground hundreds of millions of years ago has exactly zero carbon-14 in it,” Miller said. Carbon from recent biological sources, on the other hand, shows a clear carbon-14 signal.

“When all that green stuff we’re used to in Los Angeles — the plants, grasses, palm fronds — starts to decay and release its carbon dioxide back into the atmosphere, that has a non-zero carbon-14 content,” he added. “By looking at the carbon-14 value we observe, we come up with the relative fraction of the biological contribution to the total amount of carbon dioxide. The fact that the fossil-fuel carbon-14 is zero makes the math much simpler.”

Scientists also saw a carbon-14 connection in the seasonal ups and downs of carbon dioxide. Carbon-14 dropped sharply in the L.A. basin in July during the study period. That’s when watering urban landscaping — city parks, residential lawns, golf courses, and the like — peaked, causing vigorous growth. In turn, the growing plant tissue led to peak carbon-14 absorption, resulting in that sharp drop found in air samples. Absorption among California’s native forests, grasses, and shrubs peaked in early spring, a response to the region’s rainfall patterns.

Measuring carbon-14 will likely become important for more precisely evaluating carbon dioxide in other large urban areas. To effectively reduce fossil-fuel emissions, researchers need to quantify the background sources of carbon dioxide in global cities to understand how it varies with climate, latitude, degree of industrialization, and the like, Miller said, noting that there’s more work to be done.

The latest study fits into NASA’s broader portfolio of work on the carbon cycle, such as NASA’s Orbiting Carbon Observatory-3 on the International Space Station and its predecessor OCO-2, which is in Sun-synchronous oribt.

“We need to work with our colleagues in other urban areas around the world to understand these new results,” he said.

Reference: “Large and seasonally varying biospheric CO2 fluxes in the Los Angeles megacity revealed by atmospheric radiocarbon” by John B. Miller, Scott J. Lehman, Kristal R. Verhulst, Charles E. Miller, Riley M. Duren, Vineet Yadav, Sally Newman and Christopher D. Sloop, 12 October 2020, Proceedings of the National Academy of Sciences.
DOI: 10.1073/pnas.2005253117

Lung tissue of patients who suffered severely from COVID-19 shows good recovery in most cases. This was revealed by a study carried out by the Radboud university medical center that has now been published in Clinical Infectious Diseases. A striking conclusion is that the group who was referred by a GP did not recover as well as patients who were admitted to the hospital’s Intensive Care Unit (ICU).

The study, led by pulmonologist Bram van den Borst, included 124 patients who had recovered from acute COVID-19 infections. They visited the Radboud university medical center corona aftercare clinic. The patients were examined by CT scan, a lung functional test and more. After three months, the researchers took stock, which revealed that the patients’ lung tissue is recovering well. Residual damage in the lung tissue was generally limited and is most often seen in patients who were treated in the ICU.

The most common complaints after three months are fatigue, shortness of breath and chest pains. Many people also still experience limitations in their daily life as well as a decreased quality of life. Main researcher and pulmonologist Bram van den Borst explains: “The patterns we see in these patients show similarities with recovery after acute pneumonia or acute respiratory distress syndrome (ARDS), in which fluid accumulates in the lungs. Recovery from these conditions also generally takes a long time. It is encouraging to see that lungs after COVID-19 infections exhibit this level of recovery.”

Referred patients do not recover as well as admitted patients

Patients were divided into three categories for the study: a group with patients who were admitted to the ICU, a group of patients who were admitted to a nursing ward in the hospital, and finally a group with patients who could stay home but experienced persisting symptoms that eventually warranted a referral from their GP.

The study assessed how patients fared after three months and revealed that the patients who were referred to the aftercare clinic by their GP showed the worst recovery in the following period. Of course, this latter group of patients was referred because of their persisting symptoms. “However, it does seem that there is a clear subgroup of patients who initially experienced mild COVID-19 symptoms and later kept experiencing persistent long-term complaints and limitations”, Bram van den Borst elaborates. “What is striking is that we barely found any anomalies in the lungs of these patients. Considering the variety and seriousness of the complaints and the plausible size of this subgroup, there is an urgent need for further research into explanations and treatment options.”

Aftercare clinic for patients with persisting symptoms

Radboud university medical center established the corona aftercare clinic at the Dekkerswald location as a reaction to an observed increase in the signals that a substantial number of COVID-19 patients was experiencing long-term complaints, ranging from coughing, fatigue and shortness of breath to anxiety and physical limitations. At the aftercare clinic, an extensive analysis is performed involving multiple disciplines. Based on this analysis, the care requirements of the patients and the subsequent steps are determined. Patients who were admitted at Radboud university medical center with COVID-19 will receive an invitation from the corona aftercare clinic. People who went through COVID-19 from home and are still experiencing symptoms can get a referral from their GP to visit the aftercare clinic as well.

Reference: “Comprehensive health assessment three months after recovery from acute COVID-19” by Bram van den Borst, MD, PhD, Jeannette B Peters, PhD, Monique Brink, MD, PhD, Yvonne Schoon, MD, PhD, Chantal P Bleeker-Rovers, MD, PhD, Henk Schers, MD, PhD, Hieronymus W H van Hees, PhD, Hanneke van Helvoort, PhD, Mark van den Boogaard, PhD, Hans van der Hoeven, MD, PhD, Monique H Reijers, MD, PhD, Mathias Prokop, MD, PhD, Jan Vercoulen, PhD, Michel van den Heuvel, MD, PhD, 21 November 2020, Clinical Infectious Diseases.
DOI: 10.1093/cid/ciaa1750

A bladder assembloid, a reconstituted organoid with three tissue layers of the human bladder. Credit: Kunyoo Shin (POSTECH)

Organoids are organ-like tissues derived from stem cells that are grown in labs, often referred to as miniature organs. Because they can imitate the structure and function of human organs, it is considered as the next-generation technology for creating artificial organs or developing new drugs. Recently, a research team in Korea introduced a new concept of mini-organs called assembloid that surpasses these organoids to structurally and functionally recapitulate human tissues. These findings were announced in Nature, one of the most prestigious journals in science and technology.

A team led by Professor Kunyoo Shin of POSTECH’s Department of Life Sciences has developed multi-layered miniature organs called assembloids that precisely mimic human tissues by three-dimensionally reconstituting stem cells together with various cell types in tissue stroma. The assembloid is a novel, innovative technology that can present a new paradigm for the next-generation drug discovery of intractable diseases as patient-customized human organs that transcend the conventional organoids.

Organoids are miniature organs that are similar to human organs. However, the current organoid technology has a fundamental limitation in that they cannot mimic the mature structure of organs and lack the microenvironment within the tissues. Furthermore, critical interactions between various cells within the human tissues is lacking. This limitation has been considered a major issue in precisely modeling various intractable diseases including cancer.

Patient-derived bladder tumor assembloid, an in vitro tumor tissue that mimics the pathological features of the human bladder cancer. Credit: Kunyoo Shin (POSTECH)

To overcome these limitations, Shin’s team developed reconstituted in-vitro human organs called assembloids, which have organized structures of epithelial cells, stromal layers, and outer muscle cells. The researchers found that these assembloids were identical to mature adult organs in terms of cell composition and gene expression at the single cell level, and that they mimic the in-vivo regenerative response of normal tissues to the injury.

In addition, the team developed patient-specific tumor assembloids that perfectly mimic the pathological characteristics of in vivo tumors. Using this tumor assembloid platform with genetic engineering technologies, the team revealed the novel mechanisms in which the signals from the tumor microenvironment determines the plasticity of the tumor cells. These findings show that the signaling feedback between the tumor and stromal cells play a critical role in controlling the tumor plasticity. This discovery will lead to a novel paradigm in the development of cell differentiation therapy for the treatment of various aggressive types of solid cancers.

“These assembloids are the world’s first in-vitro reconstituted organoids,” explained Eunjee Kim, the first author of the paper. She added, “We can precisely model a variety of complex intractable diseases such as cancer, degenerative diseases, and various neurological diseases including schizophrenia and autism, and understand the pathogenesis of such diseases to ultimately develop better therapeutic options.”

“To our knowledge, our efforts to generate assembloids that structurally and functionally recapitulate the pathophysiology of original tissues have not been previously described,” commented Professor Shin who led the study. He added, “Generating such artificial tissues is particularly relevant to modern research because the importance of tissue microenvironments in epithelial tissue homeostasis and the growth of various tumors is increasingly being recognized. We anticipate our study to open a new era of a drug discovery that will revolutionize the advancement of patient-customized treatment for various intractable diseases.”

Professor Tae-Young Roh, who contributed to the study, remarked, “This study is a great model for interdisciplinary science, and presents a new direction for precise and personalized therapy for various human diseases.”

Reference: “Creation of bladder assembloids mimicking tissue regeneration and cancer” by Eunjee Kim, Seoyoung Choi, Byunghee Kang, JungHo Kong, Yubin Kim, Woong Hee Yoon, Hwa-Rim Lee, SungEun Kim, Hyo-Min Kim, HyeSun Lee, Chorong Yang, You Jeong Lee, Minyong Kang, Tae-Young Roh, Sungjune Jung, Sanguk Kim, Ja Hyeon Ku and Kunyoo Shin, 16 December 2020, Nature.
DOI: 10.1038/s41586-020-3034-x

The research was conducted by Professor Shin and Eunjee Kim in the MS/Ph.D. program of POSTECH’s Department of Life Sciences, and was supported by the Mid-Career Researcher Program, Brain Research Program, Regional Leading Research Center Program, and the Korea Post-Genome Project of the National Research Foundation of Korea. Professor Ja Hyun Koo of Seoul National University Hospital and POSTECH professors Sanguk Kim, Sungjune Jung, and Tae-Young Roh jointly contributed to the research.

An artistic rendering of Kraken Mare, the large liquid methane sea on Saturn’s moon Titan. Credit: NASA/John Glenn Research Center

Far below the gaseous atmospheric shroud on Saturn’s largest moon, Titan, lies Kraken Mare, a sea of liquid methane. Cornell astronomers have estimated that sea to be at least 1,000 feet deep near its center – enough room for a potential robotic submarine to explore.

After sifting through data from one of the final Titan flybys of the Cassini mission, the researchers detailed their findings in “The Bathymetry of Moray Sinus at Titan’s Kraken Mare,” which published in the Journal of Geophysical Research.

“The depth and composition of each of Titan’s seas had already been measured, except for Titan’s largest sea, Kraken Mare – which not only has a great name, but also contains about 80% of the moon’s surface liquids,” said lead author Valerio Poggiali, research associate in Cornell Center for Astrophysics and Planetary Science (CCAPS), in the College of Arts and Sciences.

A billion miles from Earth, frigid Titan is cloaked in a golden haze of gaseous nitrogen. But peeking through the clouds, the moonscape has an Earthlike appearance, with liquid methane rivers, lakes and seas, according to NASA.

In fact, the data for this discovery was gathered on Cassini’s T104 flyby of Titan on August 21, 2014. The spacecraft’s radar surveyed Ligeia Mare – a smaller sea in the moon’s northern polar region – to look for the mysteriously disappearing and reappearing “Magic Island,” which was an earlier Cornell discovery.

While Cassini cruised at 13,000 mph nearly 600 miles above Titan’s surface, the spacecraft used its radar altimeter to measure the liquid depth at Kraken Mare and Moray Sinus, an estuary located at the sea’s northern end. The Cornell scientists, along with engineers from NASA’s Jet Propulsion Laboratory, had figured out how to discern lake and sea bathymetry (depth) by noting the radar’s return time differences on the liquid surface and sea bottom, as well as the sea’s composition by acknowledging the amount of radar energy absorbed during transit through the liquid.

It turns out that Moray Sinus is about 280 feet deep, shallower than the depths of central Kraken Mare, which was too deep for the radar to measure. Surprisingly the liquid’s composition, primarily a mixture of ethane and methane, was methane-dominated and similar to the composition of nearby Ligeia Mare, Titan’s second-largest sea.

Earlier scientists had speculated that Kraken may be more ethane rich, both because of its size and extension to the moon’s lower latitudes. The observation that the liquid composition is not markedly different from the other northern seas is an important finding that will help in assessing models of Titan’s Earth-like hydrologic system.

Beyond deep, Kraken Mare also is immense – nearly the size of all five Great Lakes combined.

Titan represents a model environment of a possible atmosphere of early Earth, Poggiali said.

“In this context,” he said, “to understand the depth and composition of Kraken Mare and the Moray Sinus is important because this enables a more precise assessment on Titan’s methane hydrology. Still, we have to solve many mysteries.”

One such puzzle is the origin of the liquid methane. Titan’s solar light – about 100 times less intense than on Earth – constantly converts methane in the atmosphere into ethane; over roughly 10 million-year periods, this process would completely deplete Titan’s surface stores, according to Poggiali.

In the distant future, a submarine – likely without a mechanical engine – will visit and cruise Kraken Mare, Poggiali said.

“Thanks to our measurements,” he said, “scientists can now infer the density of the liquid with higher precision, and consequently better calibrate the sonar aboard the vessel and understand the sea’s directional flows.”

Reference: “The Bathymetry of Moray Sinus at Titan’s Kraken Mare” by V. Poggiali, A. G. Hayes, M. Mastrogiuseppe, A. Le Gall, D. Lalich, I. Gómez‐Leal and J. I. Lunine, 12 November 2020, Journal of Geophysical Research.
DOI: 10.1029/2020JE006558

Co-authors on the paper are: Alex Hayes, professor of astronomy and director of CCAPS; Jonathan Lunine, the David C. Duncan Professor in the Physical Sciences, and chair, Department of Astronomy; Marco Mastrogiuseppe, former Cornell postdoctoral researcher, now research associate at Sapienza University of Rome, Italy; Alice Le Gall, The Institut Universitaire de France, Paris; and research associates Illeana Gomez-Leal and Daniel Lalich.

NASA provided funding for this research.