Mimicking an Enigmatic Property of Circadian Rhythms through an Artificial Chemical Clock

An innovative temperature-compensation mechanism for oscillating chemical reactions based on temperature-responsive gels has been recently reported by researchers at Tokyo Tech. Their experimental findings, alongside a detailed mathematical analysis, hint at the possibility that circadian rhythms found in nature may all rely on a similar mechanism, allowing their period to remain independent of temperature.

Circadian rhythms are natural, internal oscillations that synchronize an organism's behaviors and physiological processes with their environment. These rhythms normally have a period of 24 hours and are regulated by internal chemical clocks that respond to cues from outside the body, such as light.

Although well studied in animals, plants, and bacteria, circadian rhythms all share an enigmatic property—the oscillation period is not significantly affected by temperature, even though the rate of most biochemical reactions changes exponentially with temperature. This clearly indicates that some sort of temperature-compensation mechanism is at play. Interestingly, some scientists have managed to replicate such temperature-invariant qualities in certain oscillating chemical reactions. However, these reactions are often troublesome and require extremely precise adjustments on the reacting chemicals.

Motile Sperm and Frequent Abortions in Spreading Earth moss

The protein PINC has an influence on the motility of sperm cells (left) and the anchoring of spore capsules (right, dark structures) in the moss Physcomitrella. The fluorescence microscope images in the middle show the male sex organ on the left and a young spore capsule on the right. PINC is marked in magenta.
Image Credit: Volker Lüth / University of Freiburg

Freiburg researchers discover that sperm motility and anchoring of the spore capsule in the spreading earth moss Physcomitrella are influenced by the auxin transporter PINC.

As a component of moors, mosses are important for climate conservation. They are also gaining increasing significance in biotechnology and the manufacture of biopharmaceuticals. For the most varied of rationales, mosses are interesting research objects. One reason for this is because they are particularly similar to the first land plants. As a result, they provide insight into the original function of signaling molecules which regulate growth and development in all land plants today. Researchers at the University of Freiburg and the Excellence Cluster CIBSS – Centre for Integrative Biological Signaling Studies – have discovered that transporters of the hormone auxin influence the fertility of spreading earth moss. Their observations have been published in the scientific journal New Phytologist.

MLU physicists solve mystery of two-dimensional quasicrystal formation from metal oxides

A substructure consisting of rings of different sizes embeds itself seamlessly into a hexagonal structure
 Photo Credit: Dr. Stefan Förster

The structure of two-dimensional titanium oxide breaks up at high temperatures by adding barium; instead of regular hexagons, rings of four, seven and ten atoms are created that order periodically. A team at Martin Luther University Halle-Wittenberg (MLU) made this discovery in collaboration with researchers from the Max Planck Institute (MPI) for Microstructure Physics, the Université Grenoble Alpes and the National Institute of Standards and Technology (Gaithersburg, USA), thereby solving the riddle of two-dimensional quasicrystal formation from metal oxides. Their findings have been published in the renowned journal "Nature Communications".

Hexagons are frequently found in nature. The best-known example is honeycomb, but graphene or various metal oxides, such as titanium oxide, also form this structure. "Hexagons are an ideal pattern for periodic arrangements," explains Dr Stefan Förster, researcher in the Surface and Interface Physics group at MLU’s Institute of Physics. "They fit together so perfectly that there are no gaps." In 2013, this group made an astonishing discovery upon depositing an ultrathin layer containing titanium oxide and barium on a platinum substrate and heating it to around 1,000 degrees centigrade in an ultra-high vacuum. The atoms arranged themselves into triangles, squares and rhombuses that group in even larger symmetrical shapes with twelve edges. A structure with 12-fold rotational symmetry was created, instead of the expected 6-fold periodicity. According to Förster, "Quasicrystals were created that have an aperiodic structure. This structure is made of basic atomic clusters that are highly ordered, even if the systematics behind this ordering is difficult for the observer to discern." The physicists from Halle were the first worldwide to demonstrate the formation of two-dimensional quasicrystals in metal oxides. 

Humans have influenced the growth of blue-green algae in lakes for thousands of years

TERENO Monitoring Station on Lake Tiefer See, Germany (weather station, water probes, sediment traps).
Photo Credit: A. Brauer

In recent years, there have been increasing reports of toxic blue-green algae blooms in summer, even in German lakes, caused by climate warming and increased nutrient inputs. But humans have not only had an influence on the development of blue-green algae since modern times, but already since the Bronze Age from about 2,000 B.C. This is the result of a study by researchers from the German Research Centre for Geosciences GFZ and colleagues, published in the scientific journal “Communications Biology”. Since some blue-green algae, also known as cyanobacteria, leave no visible fossil traces in sediments due to their small size, little is known about how they evolved in our lakes during the last centuries and millennia. Using DNA from sediments, the researchers have now been able to decipher for the first time the history of blue-green algae over the last 11,000 years in the sediments of a lake in Mecklenburg.

Artificial photosynthesis uses sunlight to make biodegradable plastic

Fumaric acid synthesis from CO2 using solar energy. Using sunlight to power the photoredox system pyruvic acid and CO2 are converted into fumaric acid, by malate dehydrogenase and fumarase.
Illustration Credit: Yutaka Amao, Osaka Metropolitan University

In recent years, environmental problems caused by global warming have become more apparent due to greenhouse gases such as CO2. In natural photosynthesis, CO2 is not reduced directly, but is bound to organic compounds which are converted to glucose or starch. Mimicking this, artificial photosynthesis could reduce CO2 by combining it into organic compounds to be used as raw materials, which can be converted into durable forms such as plastic.

A research team led by Professor Yutaka Amao from the Research Center for Artificial Photosynthesis and graduate student Mika Takeuchi, from the Osaka Metropolitan University Graduate School of Science, have succeeded in synthesizing fumaric acid from CO2, a raw material for plastics, powered—for the first time—by sunlight. Their findings were published in Sustainable Energy & Fuels.

Probe can measure both cell stiffness and traction, researchers report

Professor Ning Wang, front right, is joined by researchers, from left, Fazlur Rashid, Kshitij Amar and Parth Bhala.
Photo Credit: Fred Zwicky

Scientists have developed a tiny mechanical probe that can measure the inherent stiffness of cells and tissues as well as the internal forces the cells generate and exert on one another. Their new “magnetic microrobot” is the first such probe to be able to quantify both properties, the researchers report, and will aid in understanding cellular processes associated with development and disease.

They detail their findings in the journal Science Robotics.

“Living cells generate forces through protein interactions, and it’s very hard to measure these forces,” said Ning Wang, a professor of mechanical science and engineering at the University of Illinois Urbana-Champaign who led the research. “Most probes can either measure the forces actively generated by the tissues and cells themselves, a trait we call traction, or they can measure their stiffness – but not both.”

To measure cell stiffness, researchers need a relatively rigid probe that can compress, stretch or twist the tissues and quantify how robustly they resist. But to measure the cells’ own internally generated contractions or expansions, a probe must be relatively soft and supple.

Like other scientists, Wang and his colleagues had already developed probes to measure each of these qualities individually. But he said he wanted to develop a more universal probe that could tackle both at once. Such a probe would allow a better understanding of how these properties influence diseases like arteriosclerosis or cancer, or how an embryo develops, for example.

Risk of developing heart failure much higher in rural areas vs. urban

Photo Credit: Tumisu

Large NIH-supported study showed that rural-dwelling Black men are at greatest risk.

Adults living in rural areas of the United States have a 19% higher risk of developing heart failure compared to their urban counterparts, and Black men living in rural areas have an especially higher risk – 34%, according to a large observational study supported by the National Institutes of Health.

The study, one of the first to look at the link between living in rural America and first-time cases of heart failure, underscores the importance of developing more customized approaches to heart failure prevention among rural residents, particularly Black men. The study was largely funded by the National Heart, Lung, and Blood Institute (NHLBI), part of NIH, and the findings, produced in collaboration with Vanderbilt University Medical Center, Nashville, Tennessee, published today in JAMA Cardiology.

“We did not expect to find a difference of this magnitude in heart failure among rural communities compared to urban communities, especially among rural-dwelling Black men,” said Véronique L. Roger, M.D., M.P.H., the study’s corresponding author and a senior investigator with the Epidemiology and Community Health Branch in NHLBI’s Division of Intramural Research. “This study makes it clear that we need tools or interventions specifically designed to prevent heart failure in rural populations, particularly among Black men living in these areas.”

What crocodile DNA reveals about the Ice Age

McGill University postdoctoral fellow José Avila-Cervantes with an American Crocodile (Crocodylus acutus).
Photo Credit: Hans Larsson

What drives crocodile evolution? Is climate a major factor or changes in sea levels? Determined to find answers to these questions, researchers from McGill University discovered that while changing temperatures and rainfall had little impact on the crocodiles’ gene flow over the past three million years, changes to sea levels during the Ice Age had a different effect.

“The American crocodile tolerates huge variations in temperature and rainfall. But about 20,000 years ago – when much of the world's water was frozen, forming the vast ice sheets of the last glacial maximum – sea levels dropped by more than 100 meters. This created a geographical barrier that separated the gene flow of crocodiles in Panama,” says postdoctoral fellow José Avila-Cervantes, working under the supervision of McGill professor Hans Larsson.

Thermal motions and oscillation modes determine the uptake of bacteria in cells

Photo of a membrane bubble with different oscillation modes in the background and experimental scheme in the foreground. Optical tweezers (laser focus in red) bring a thermally fluctuating particle into contact with a membrane bubble (green) until the particle is invaginated into the membrane and taken up.
Graphic Credit: AG Rohrbach

How and with what effort does a bacterium - or a virus - enter a cell and cause an infection? Researchers from Freiburg have now made an important contribution to answering this question: A team led by physicist Prof. Dr. Alexander Rohrbach and his collaborator Dr. Yareni Ayala was able to show how thermal fluctuations of a model bacterium and membrane oscillation modes of a model cell influence the energy with which the model bacteria dock and enter the membrane. The results have just been published in the journal Nature Communications.

Like a sticky piece of candy on a wobbly balloon

“To understand how a bacterium or virus enters a cell, you can imagine a sticky candy on a floppy, wobbly balloon. When a child shakes the rubber balloon around, the candy sticks even tighter to its surface,” said Rohrbach, a professor of -Bio- and Nano-Photonics at the Department of Microsystems Engineering at the University of Freiburg. In his lab, the laser and bio-physicists set up a similar experiment to study the physics of infection processes. The wobbly balloon corresponds to a giant uni-lamellar vesicle (GUV), which serves as a biological model cell. The membrane vesicle is the size of a tiny grain of sand about 20 micrometers in diameter.

COVID-19 conspiracy theories that spread fastest focused on evil, secrecy

Covid 19 Conspiracy Initiated
Image Credit: Dr StClaire

In the early pandemic, conspiracy theories that were shared the most on Twitter highlighted malicious purposes and secretive actions of supposed bad actors behind the crisis, according to an analysis of nearly 400,000 posts. 

In the study, researchers identified commonalities in five of the most popular conspiracy theories: those related to Bill Gates, 5G Networks, vaccinations, QAnon and Agenda 21.

While each theory appears to have a different subject, the social media narratives often overlapped, said Porismita Borah, associate professor in Washington State University’s Murrow College of Communications.

“The conspiracy theories might be using different strategies, but the narratives are often connected,” said Borah, the corresponding author on the study published in the journal New Media and Society. “These theories have a lot in common in that they try to make the stories part of a bigger conspiracy so that if people believe in one conspiracy, then they tend to believe in the other.”