Tropical Forests Benefit Less from Elevated Atmospheric CO2 Than Thought

Tropical vegetation near Lake Bosumtwi in Ghana.
Photo credit: William Gosling.

The amount of carbon dioxide (CO2) in the Earth’s atmosphere has only a small influence on changes in tropical ecosystems despite evidence of enhanced plant growth under elevated CO2 scenarios in greenhouse experiments, according to a new international study.

That means it’s unlikely that tropical forests will expand in response to rising greenhouse gas levels, an outcome that some had hoped might lead to increased CO2 storage in tropical ecosystems as carbon-rich woody plants replace grasslands, which are less adept at storing CO2.

The study was published May 5 in Science. The research team was made up of scientists from the Netherlands, United Kingdom and United States, including scientists at The University of Texas at Austin.

The researchers analyzed 500,000 years of tropical vegetation change in West Africa and found that CO2 had less of an influence on tropical forest growth than water, wildfires and animal grazing did.

“When you scale up to the landscape scale, the resources available and processes occurring within that landscape are more important than the CO2 fertilization,” said the study’s lead author, William Gosling of the Institute for Biodiversity and Ecosystem Dynamics at the University of Amsterdam.

Model finds COVID-19 deaths among elderly may be due to genetic limit on cell division

This illustration represents the core theory in a new modeling study led by the University of Washington: The circles represent the immune system’s aging, in which its ability to make new immunity cells remains constant until a person (represented by the human figures) reaches middle-age or older and then falls off significantly. The central blue figure represents an immune system T cell that attacks the virus.
Credit: Michele Kellett and James Anderson/University of Washington

Your immune system’s ability to combat COVID-19, like any infection, largely depends on its ability to replicate the immune cells effective at destroying the SARS-CoV-2 virus that causes the disease. These cloned immune cells cannot be infinitely created, and a key hypothesis of a new University of Washington study is that the body’s ability to create these cloned cells falls off significantly in old age.

According to a model created by UW research professor James Anderson, this genetically predetermined limit on your immune system may be the key to why COVID-19 has such a devastating effect on the elderly. Anderson is the lead author of a paper published in The Lancet eBioMedicine detailing this modeled link between aging, COVID-19 and mortality.

“When DNA split in cell division, the end cap — called a telomere — gets a little shorter with each division,” explains Anderson, who is a modeler of biological systems in the School of Aquatic and Fishery Sciences. “After a series of replications of a cell, it gets too short and stops further division. Not all cells or all animals have this limit, but immune cells in humans have this cell life.”

Treatment for blinding blood vessel condition yields lasting vision improvement

A Penn State College of Medicine researcher and colleagues found that a treatment for retinal vein occlusion — one of the most common blinding conditions in the United States — may lead to long-term vision improvement.
Credit: Penn State College of Medicine / Penn State.

A treatment for retinal vein occlusion (RVO) — one of the most common blinding conditions in the United States — may lead to long-term vision improvement, according to new research published by a Penn State College of Medicine researcher and colleagues.

Without treatment, central retinal vein occlusion, the most severe type of retinal vein occlusion, often leads to significant and permanent vision loss. The disease can cause obstruction of the veins carrying blood away from the retina, the light-sensitive tissue at the back of the eye. This can lead to macular edema, where fluid becomes trapped within and under the retina, leading to rapid and severe loss of visual acuity. Injections of anti-vascular endothelial growth factor (anti-VEGF) drugs may help control blood vessel leakage and swelling in the retina and are considered the most effective treatment.

A report on five-year outcomes of the Study of Comparative Treatments for Retinal Vein Occlusion 2 (SCORE2), was published in the American Journal of Ophthalmology. Dr. Ingrid Scott, Jack and Nancy Turner Professor of Ophthalmology and professor of public health sciences, received more than $11 million from the National Eye Institute, a part of the National Institutes of Health, to lead the study.

Dog coronavirus jumps to humans, with a protein shift

N-terminus: The end of a peptide or protein primary structure in which the amino acid residue is not part of a peptide bond. The terminal group is often (but not always) an amine or ammonium cation.

Cornell researchers have identified a shift that occurs in canine coronavirus that points to a possible pattern of change found in other coronaviruses and which may provide clues to how they transmit to humans from animals.

A new canine coronavirus was first identified in two Malaysian human patients who developed pneumonia in 2017-18. A group of other scientists isolated the canine coronavirus, sequenced it and published their findings in 2021.

Now, a team led by Cornell and Temple University researchers has identified a pattern that occurs in a terminus of the canine coronavirus spike protein – the area of the virus that facilitates entry into a host cell: The virus shifts from infecting both the intestines and respiratory system of the animal host to infecting only the respiratory system in a human host.

The researchers identified a change in the terminus – known as the N terminus – a region of the molecule with alterations also detected in another coronavirus, which jumped from bats to humans, where it causes a common cold.

New nanotech imaging tool may allow smartphone disease diagnosis

This new technology could allow people to use the camera on their smartphone to diagnose diseases.
Credit: TMOS

Scientists have developed a low-cost microscopic imaging device small enough to fit on a smartphone camera lens, with the potential to make mobile medical diagnosis of diseases affordable and accessible.

Research published today in ACS Photonics from researchers at the University of Melbourne and the Australian Research Council Centre of Excellence for Transformative Meta-Optical Systems (TMOS), is helping miniaturize phase-imaging technology using metasurfaces, which are only a few hundred nanometers thick – about 350 times thinner than the thickness of a human hair – thus small enough to fit in the lens of a smartphone or other small camera.

The detection of diseases often relies on optical microscope technology to investigate changes in biological cells. Currently, these investigation methods usually involve staining the cells with chemicals in a laboratory environment as well as using specialized ‘phase-imaging’ microscopes. These aim to make invisible aspects of a biological cell visible, so early-stage detection of disease becomes possible. However, phase-imaging microscopes are bulky and cost thousands of dollars, putting them out of reach of remote medical practices.

‘Resetting’ the injured brain offers clues for concussion treatment

Jonathan Godbout, professor of neuroscience
Credit: Ohio State University

New research in mice raises the prospects for development of post-concussion therapies that could ward off cognitive decline and depression, two common conditions among people who have experienced a moderate traumatic brain injury.

The study in mice clarified the role of specific immune cells in the brain that contribute to chronic inflammation. Using a technique called forced cell turnover, researchers eliminated these cells in the injured brains of mice for a week and then let them repopulate for two weeks.

“It’s almost like hitting the reset button,” said senior study author Jonathan Godbout, professor of neuroscience in The Ohio State University College of Medicine.

Compared to brain-injured mice recovering naturally, mice that were given the intervention showed less inflammation in the brain and fewer signs of thinking problems 30 days after the injury.

Though temporarily clearing away these cells, called microglia, in humans isn’t feasible, the findings shed light on pathways to target that could lower the brain’s overall inflammatory profile after a concussion, potentially reducing the risk for behavioral and cognitive problems long after the injury.

“In a moderate brain injury, if the CT scan doesn’t show damage, patients go home with a concussion protocol. Sometimes people come back weeks, months later with neuropsychiatric issues. It’s a huge problem affecting millions of people,” said Godbout, faculty director of Ohio State’s Chronic Brain Injury Program and assistant director of basic science in the Institute for Behavioral Medicine Research.

Hydroponic native plants to detox PFAS-contaminated water

PFAS can be removed from contaminated water by Australian native rushes.

They’re the non-stick on Teflon cookware, the stain resistance in Scotchgard, and the suppression factor in firefighting foam, but while the staying power of PFAS chemicals was once revered, it’s now infamous as PFAS substances continue to infiltrate the environment and affect human health.

Now, new research from the University of South Australia is helping to remediate the ‘indestructible’ PFASs as scientists show that Australian native plants can significantly remediate PFAS pollutants through floating wetlands to create healthier environments for all.

Conducted in partnership with CSIRO and the University of Western Australia, the research found that PFAS chemicals (per- and poly-fluoroalkyl substances) can be removed from contaminated water via Australian native rushes - Phragmites australis, Baumea articulata, and Juncus kraussii.

Phragmites australis, otherwise known as the common reed, removed legacy PFAS contaminants by 42-53 per cent from contaminated surface water (level: 10 µg/L).

Decreased Genetic Diversity in Immune System Could Impact Endangered Toad Survival

Anaxyrus baxteri, the Wyoming toad.

A new study from North Carolina State University examines immune system diversity in the critically endangered Wyoming toad and finds that genetic bottlenecks could impact a species’ ability to respond to new pathogens. The findings could inform captive breeding strategies for endangered animal populations.

The Wyoming toad, Anaxyrus baxteri, suffered a severe population decline throughout the latter part of the 20th century due to factors including habitat destruction and fungal infection. The toad was brought into a captive breeding program in the 1990s in order to save the species. Scientists estimate a current wild population of only 400 to 1,500 animals, meaning that the toad is considered critically endangered.

“Population reduction in this species created a genetic bottleneck to begin with, meaning the level of genetic diversity is already very small,” says Jeff Yoder, professor of comparative immunology at NC State and co-corresponding author of a paper describing the work. “This is the first study to look specifically at genetic diversity in the immune systems of these toads and how it could impact them as a population.”

Yoder, with co-corresponding author Alex Dornburg of the University of North Carolina at Charlotte, performed RNA sequencing on immune tissues from three healthy, retired Wyoming toad breeders. Study co-author Michael Stoskopf, who was on the Wyoming Toad Recovery Implementation Team established in 2008, obtained the samples.

Search reveals eight new sources of black hole echoes

In this illustration, a black hole pulls material off a neighboring star and into an accretion disk.
Credits: Aurore Simonnet and NASA’s Goddard Space Flight Center

Scattered across our Milky Way galaxy are tens of millions of black holes — immensely strong gravitational wells of spacetime, from which infalling matter, and even light, can never escape. Black holes are dark by definition, except on the rare occasions when they feed. As a black hole pulls in gas and dust from an orbiting star, it can give off spectacular bursts of X-ray light that bounce and echo off the inspiraling gas, briefly illuminating a black hole’s extreme surroundings.

Now MIT astronomers are looking for flashes and echoes from nearby black hole X-ray binaries — systems with a star orbiting, and occasionally being eaten away by, a black hole. They are analyzing the echoes from such systems to reconstruct a black hole’s immediate, extreme vicinity.

In a study appearing today in the Astrophysical Journal, the researchers report using a new automated search tool, which they’ve coined the “Reverberation Machine,” to comb through satellite data for signs of black hole echoes. In their search, they have discovered eight new echoing black hole binaries in our galaxy. Previously, only two such systems in the Milky Way were known to emit X-ray echoes.

In comparing the echoes across systems, the team has pieced together a general picture of how a black hole evolves during an outburst. Across all systems, they observed that a black hole first undergoes a “hard” state, whipping up a corona of high-energy photons along with a jet of relativistic particles that is launched away at close to the speed of light. The researchers discovered that at a certain point, the black hole gives off one final, high-energy flash, before transitioning to a “soft,” low-energy state.

Researchers Create Self-Assembled Logic Circuits from Proteins

In a proof-of-concept study, researchers have created self-assembled, protein-based circuits that can perform simple logic functions. The work demonstrates that it is possible to create stable digital circuits that take advantage of an electron’s properties at quantum scales.

One of the stumbling blocks in creating molecular circuits is that as the circuit size decreases the circuits become unreliable. This is because the electrons needed to create current behave like waves, not particles, at the quantum scale. For example, on a circuit with two wires that are one nanometer apart, the electron can “tunnel” between the two wires and effectively be in both places simultaneously, making it difficult to control the direction of the current. Molecular circuits can mitigate these problems, but single-molecule junctions are short-lived or low-yielding due to challenges associated with fabricating electrodes at that scale.

“Our goal was to try and create a molecular circuit that uses tunneling to our advantage, rather than fighting against it,” says Ryan Chiechi, associate professor of chemistry at North Carolina State University and co-corresponding author of a paper describing the work.