Senescent Cells Key to Axolotl Limb Regeneration

Axolotl – the Mexican salamander with unique regenerative abilities helps scientists uncover the molecular mechanisms of regeneration.
Photo Credit: © TUD/CRTD

Scientific Frontline: Extended "At a Glance" Summary: Senescent Cells in Axolotl Limb Regeneration

The Core Concept: Senescent cells, typically associated with cellular aging and deterioration, play a critical, beneficial, and transient role in driving the regeneration of complex body parts, such as limbs, in axolotls.

Key Distinction/Mechanism: Unlike their traditional characterization as inactive, harmful "zombie cells" that accumulate during aging, senescent cells in a regenerating axolotl blastema actively modulate their microenvironment. They secrete molecules via the Wnt signaling pathway that simultaneously stimulate neighboring progenitor cells to proliferate and prevent them from entering senescence themselves, thereby facilitating rapid tissue regrowth.

Long COVID most prevalent in the most seriously ill

Image Credit: Scientific Frontline

A collaborative study involving researchers from Karolinska Institutet has charted the prevalence of severe physical symptom burden amongst Scandinavians for up to two years after a SARS-CoV-2 infection. Most affected were people who had a severe COVID-19 infection, while the researchers found no elevated prevalence of long COVID in those who had never been bedridden. The study is published in The Lancet Regional Health – Europe.

By mid-October 2023, over 771 million cases of COVID-19 had been reported to the World Health Organization (WHO). An estimated 10 to 20 per cent of the affected have persistent symptoms.

Close to 65,000 participants

In the present study, researchers examined the prevalence of persistent physical symptoms in people with different degrees of COVID-19 severity and compared them with people who had not had a confirmed COVID-19 diagnosis. The study comprised 64,880 adults from Sweden, Denmark, Norway and Iceland with self-reported physical symptoms between April 2020 and August 2022.

Over 22,000 of the participants were diagnosed with COVID-19 during the period, almost 10 per cent of whom were bedridden for at least seven days. The prevalence of chronic symptoms such as shortness of breath, chest pain, dizziness, headaches, and low energy/ fatigue, was 37 per cent higher in those who had had a COVID-19 diagnosis than in those who had not.

Carbon copy: new method of recycling carbon fiber shows huge potential

UNSW Canberra researcher Di He with a sample of carbon fiber recycled using a method he developed.
 Photo Credit: UNSW Canberra

Ultra-light cars made from recycled carbon fiber are a step closer, thanks to a new method of recycling developed at UNSW Canberra. 

As manufacturing and technology continually take steps forward, products are using more advanced materials and becoming more sophisticated, but also more complicated.

This presents a problem when these products reach the end of their useable life, because they’re either difficult or expensive to recycle, or both.

For example, as the world transitions to electric vehicles, disposing of their used batteries, some made with highly toxic materials, will be a challenge.

As it stands, many advanced products either end up in landfill or incinerated, which is a waste of valuable resources and harmful to the planet.

One material that has been difficult to recycle is carbon fiber.

Alpine rock reveals dynamics of plate movements in Earth’s interior

Professor Lucie Tajčmanová, Heidelberg University, examines the whiteschist sample from the Dora Maira Massif of the Western Alps.
Photo Credit: Sebastian Cionoiu, Heidelberg University

Examining how plates move in Earth's mantle and how mountains form is no easy feat. Certain rocks that have sunk deep into Earth's interior and then returned from there can deliver answers. Led by the Department of Geosciences at Goethe University Frankfurt, an international team of geologists has now succeeded in analyzing whiteschist from the Alps so precisely by means of computer modeling that it calls a previous theory about plate movement into question. 

Geoscientists analyze rocks in mountain belts to reconstruct how they once moved downwards into the depths and then returned to the surface. This history of burial and exhumation sheds light on the mechanisms of plate tectonics and mountain building. Certain rocks that sink far down into Earth's interior together with plates are transformed into different types under the enormous pressure that prevails there. During this UHP metamorphosis (UHP: Ultra High Pressure), silica (SiO2) in the rock, for example, becomes coesite, which is also referred to as the UHP polymorph of SiO2. Although it is chemically still silica, the crystal lattices are more tightly packed and therefore denser. When the plates move upwards again from the depths, the UHP rocks also come to the surface and can be found in certain places in the mountains. Their mineral composition provides information about the pressures to which they were exposed during their vertical journey through Earth's interior. Using lithostatic pressure as a unit of measurement, it is possible to correlate pressure and depth: the higher the pressure, the deeper the rocks once lay. 

Cancer's sweet Achilles heel

Weakly immunogenic and strongly immunogenic tumor cells were subcutaneously transplanted into B4GALT3 knockout and wild-type mice. Tumor cell growth was significantly suppressed in knockout mice.
Illustration Credit: KyotoU Jake Tobiyama/Heng Wei

An old campaign slogan for cough syrup, "It tastes awful. And it works," seemed to imply that any sweet content might have diminished the medicinal effect.

Sweetness, in the case of cancer, appears as a chain of sugar molecules attached to proteins by beta1,4-galactosyltransferase-3, or B4GALT3. According to the Cancer Genome Atlas, a high expression of this enzyme is associated with noticeably shortened survival rates in several types of immunotherapy cancers, such as neuroblastoma, cervical, and bladder cancer. However, the specific role of B4GALT3 in the tumor immune microenvironment -- or TIME -- was still unknown.

Now, a team of researchers at Kyoto University and Yokohama City University has found that B4GALT3 deficiency in mice TIME inhibits tumor growth. The study shows that a significant reduction of glycosylation -- a type of protein modification -- on T cell surfaces correlates with increases in CD8+ immune cells infiltrating tumors.

Stunting in infancy linked to differences in cognitive and brain function

Photo Credit: bethL

Children who are too short for their age can suffer reduced cognitive ability arising from differences in brain function as early as six months of age, according to new research.

Researchers from the University of Nottingham were part of a team led by the University of East Anglia who compared the ‘visual working memory’ – the memory capacity that holds visual cues for processing – in children who had stunted growth with those having typical growth.

Published today in the journal Nature Human Behavior, the study found that the visual working memory of infants with poor physical growth was disrupted, making them more easily distracted and setting the stage for poorer cognitive ability one year later.

Stunted growth had previously been linked with poor cognitive outcomes later in life, but this is the first time that this association has been found in infancy. It is also the first time stunted growth has been linked to functional differences in how the brain works in early development.

Decoding Past Climates through Dripstones

NATURAL ARCHIVES: “Dripstones, or speleothems, are unique natural archives.
Photo Credit: Zarko Tankosic

A recent study demonstrates how dripstones can be crucial for reconstructing past climates. The new approach can provide a detailed picture of the climate around early human occupations in South Africa.

“Dripstones, or speleothems, are unique natural archives - like Earth’s USB sticks. They store a wealth of information on past climate which helps us to better understand the environment in which early humans lived”, Jenny Maccali explained. She is a scientist at SapienCE Centre of Excellence, and has led the study, now published in Climate of the Past.

New perspective to ancient climate

South Africa has a highly dynamic climate resulting from its position at the convergence of two oceanic basins, the Atlantic Ocean to the west and the Indian Ocean to the east. The region is also located at the boundary of different climate zones (subtropical vs. temperate), and the proximity of the Antarctic ice sheet has a direct impact on its climate by influencing the easterlies and westerlies winds position, and hence rainfall pattern.

Unconventional Approach to C. Diff

C. difficile bacteria seen through a scanning electron microscope and colored green.
Image Credit: Janice Carr via CDC

Clostridioides difficile (C. diff) intestinal infections can cause severe, debilitating diarrhea in patients who are hospitalized or on immunosuppressive therapies. The infections can be very hard to eradicate, roaring back when patients try to taper their antibiotics. Many people wind up on antibiotics for months and can become resistant to three or more of them.

“Often being on antibiotics isn’t sufficient,” explained Meenakshi Rao, Harvard Medical School assistant professor of pediatrics at Boston Children’s Hospital. “The infection can catalyze severe, runaway inflammation, especially in patients with inflammatory bowel disease.”

This inflammation, in turn, promotes C. diff colonization of intestinal tissue. And antibiotics themselves could be part of the problem.

“Once we attack C. diff with antibiotics, it disrupts the gut microbiome,” said Min Dong, HMS associate professor of surgery at Boston Children’s, whose lab studies bacterial toxins and how to combat them. “That creates an opportunity for severe, recurring infection, and it becomes a vicious cycle.”

Venus had Earth-like plate tectonics billions of years ago

Photo Credit: NASA/JPL

A new study found that Venus, a scorching wasteland of a planet according to scientists, may have once had tectonic plate movements similar to those believed to have occurred on early Earth, a new study found. The finding sets up tantalizing scenarios regarding the possibility of early life on Venus, its evolutionary past and the history of the solar system.

Writing in Nature Astronomy, a team of scientists led by Brown University researchers describes using atmospheric data from Venus and computer modeling to show that the composition of the planet’s current atmosphere and surface pressure would only have been possible as a result of an early form of plate tectonics, a process critical to life that involves multiple continental plates pushing, pulling and sliding beneath one another.

On Earth, this process intensified over billions of years, forming new continents and mountains, and leading to chemical reactions that stabilized the planet’s surface temperature, resulting in an environment more conducive to the development of life.

Fruit, nectar, bugs and blood: How bat teeth and jaws evolved for a diverse dinnertime

A side-view image of the skull of a greater spear-nosed bat, Phyllostomus hastatus, a noctilionoid species with an omnivorous diet.
Photo Credit: Sharlene Santana/University of Washington

They don’t know it, but Darwin’s finches changed the world. These closely related species — native to the Galapagos Islands — each sport a uniquely shaped beak that matches their preferred diet. Studying these birds helped Charles Darwin develop the theory of evolution by natural selection.

A group of bats has a similar — and more expansive — evolutionary story to tell. There are more than 200 species of noctilionoid bats, mostly in the American tropics. And despite being close relatives, their jaws evolved in wildly divergent shapes and sizes to exploit different food sources. A paper published in Nature Communications shows those adaptations include dramatic, but also consistent, modifications to tooth number, size, shape and position. For example, bats with short snouts lack certain teeth, presumably due to a lack of space. Species with longer jaws have room for more teeth — and, like humans, their total tooth complement is closer to what the ancestor of placental mammals had.