Study of slowly evolving ‘living fossils’ reveals key genetic insights

The alligator gar, and other gar species, are “living fossils” that it shows little species diversity or physical differences from ancestors that lived tens of millions of years ago.
Photo Credit: David Solomon

In 1859, Charles Darwin coined the term “living fossils” to describe organisms that show little species diversity or physical differences from their ancestors in the fossil record. In a new study, Yale researchers provide the first evidence of a biological mechanism that explains how living fossils occur in nature.

The study, published in the journal Evolution, shows that gars — an ancient group of ray-finned fishes that fit the definition of a living fossil — have the slowest rate of molecular evolution among all jawed vertebrates, meaning their genome changes more slowly than those of other animals.

By linking this finding to the process of hybridization — when two different species produce viable offspring — of gar species in the wild that last shared common ancestry during the age of the dinosaurs, the researchers demonstrate that slow evolution rate of their genome drives their low species diversity.

“We show that gars’ slow rate of molecular evolution has stymied their rate of speciation,” said Thomas J. Near, professor of Ecology and Evolutionary Biology in Yale’s Faculty of Arts and Sciences and the paper’s senior author. “Fundamentally, this is the first instance where science is showing that a lineage, through an intrinsic aspect of its biology, fits the criteria of living fossils.” 

Study shows social factors of low U.S. Breast cancer screening

Photo Credit: Marco Jean deOliveira Teixeira

To identify major social factors hindering breast cancer screening in women aged 40 and older in the U.S., researchers focused on race/ethnicity, employment, education, food security, insurance status, housing and access to quality health care.

There is a pressing need to explore and understand which social determinants of health (SDOH) and health inequities act as significant influential factors that contribute to low breast cancer screening behaviors in the United States.

Health disparities have been consistently associated with delayed screening, which then contributes to higher mortality rates among both Hispanic and Black populations. Moreover, poverty, lack of education, neighborhood disadvantage, residential segregation, racial discrimination, lack of social support and social isolation also play a role in the breast cancer stage at diagnosis.

Researchers from Florida Atlantic University’s Schmidt College of Medicine conducted a scoping review of 72 peer-reviewed observational studies published between 2013 and 2023 to identify the major SDOH that hinder breast cancer screening in women aged 40 and older in the U.S. They focused on race/ethnicity, employment, education, food security, insurance status, housing and access to quality health care.

Low iron levels resulting from infection could be key trigger of long COVID

Photo Credit: Malachi Cowie

Problems with iron levels in the blood and the body’s ability to regulate this important nutrient as a result of SARS-CoV-2 infection could be a key trigger for long COVID, new research has discovered.

"Iron levels, and the way the body regulates iron, were disrupted early on during SARS-CoV-2 infection, and took a very long time to recover, particularly in those people who went on to report long COVID months later"

Aimee Hanson

The discovery not only points to possible ways to prevent or treat the condition, but could help explain why symptoms similar to those of long COVID are also commonly seen in a number of post-viral conditions and chronic inflammation.

Although estimates are highly variable, as many as three in 10 people infected with SARS-CoV-2 could go on to develop long COVID, with symptoms including fatigue, shortness of breath, muscle aches and problems with memory and concentration (‘brain fog’). An estimated 1.9 million people in the UK alone were experiencing self-reported long COVID as of March 2023, according to the Office of National Statistics.

Shortly after the start of the COVID-19 pandemic, researchers at the University of Cambridge began recruiting people who had tested positive for the virus for the COVID-19 cohort of the National Institute for Health and Care Research (NIHR) BioResource. These included asymptomatic healthcare staff identified via routine screening through patients admitted to Cambridge University Hospitals NHS Foundation Trust, and some to its intensive care unit.

Umbrella for Atoms: The First Protective Layer for 2d Quantum Materials

Amalgamation of experimental images. At the top, a scanning tunneling microscopy image displays the graphene’s honeycomb lattice (the protective layer). In the center, electron microscopy shows a top view of the material indenene as a triangular lattice. Below it is a side view of the silicon carbide substrate. It can be seen that both the indenene and the graphene consist of a single atomic layer.
Image Credit: © Jonas Erhardt/Christoph Maeder

As silicon-based computer chips approach their physical limitations in the quest for faster and smaller designs, the search for alternative materials that remain functional at atomic scales is one of science's biggest challenges. In a groundbreaking development, researchers at the Würzburg-Dresden Cluster of Excellence ct.qmat have engineered a protective film that shields quantum semiconductor layers just one atom thick from environmental influences without compromising their revolutionary quantum properties. This puts the application of these delicate atomic layers in ultrathin electronic components within realistic reach. The findings have just been published in Nature Communications.

2D Quantum Materials Instead of Silicon

The race to create increasingly faster and more powerful computer chips continues as transistors, their fundamental components, shrink to ever smaller and more compact sizes. In a few years, these transistors will measure just a few atoms across – by which point, the miniaturization of the silicon technology currently used will have reached its physical limits. Consequently, the quest for alternative materials with entirely new properties is crucial for future technological advancements.

Dopamine production is not behind vulnerability to cocaine abuse

Averaged parametric brain maps of [18F]-FDOPA kicer, and index of dopamine synthesis capacity, in high- and low-impulsive rats before and after repeated cocaine self-administration.
Image Credit: © 2024 Urueña-Méndez et al.

Why do some people who try drugs struggle with substance abuse while others don’t? This question has long puzzled scientists. A team from the University of Geneva (UNIGE) explored the complex interplay between personality traits and brain chemistry. The scientists studied the role of impulsivity and the production of dopamine – the so-called "happiness hormone" – in influencing the risk of cocaine abuse. These results, published in eNeuro, offer new keys to understanding vulnerability to drug abuse, which could lead to the development of more targeted interventions for people at risk.

When a person consumes an addictive drug, his or her dopamine release surges, creating a “high” feeling. With repeated drug use, this dopamine release drops, potentially driving the person to increase drug consumption. This mechanism varies between individuals, with some showing a greater propensity to consume the drug while others don’t. However, the reasons for these differences are unknown.

Water May Have Flowed Intermittently in Martian Valleys for Hundreds of Millions of Years

Detail of an unnamed valley network on Mars. Impact craters are marked with blue and red circles. Craters marked in red postdate the valley network while those marked in blue predate the valley network. Dashed circles have a lower degree of superposition certainty with the valley network. Dashed black line is the mapped valley network. (a) overview of the valley system. The entire basin is outlined in white; the highland areas that have undergone less erosion are outlined in black. (b) detail of the area marked in (a).
Image Credit: MOLA MEGDR, NASA/USGS; THEMIS mosaic, ASU/NASA/USGS; CTX, NASA/MSSS.

Using impact craters as a dating tool, Planetary Science Institute Research Scientist Alexander Morgan has determined maximum timescales for the formation of Martian valley networks shaped by running water.

“Mars today is a global desert, but its surface preserves extensive evidence of past flowing water, including what appear to be river valleys. The timescale over which these valleys formed has big implications for early Mars’ habitability, as long eras with stable liquid water would be more conducive to life,” said Morgan, sole author of “New maximum constraints on the era of Martian valley network formation” that appears in Earth and Planetary Science Letters.

Martian valley networks formed more than 3 billion years ago and have long been considered among the strongest pieces of evidence of liquid water on early Mars. Previous work has found that it took a minimum of tens of thousands of years to erode these valleys, but the frequency of flow events, and thus the total time era over which the valleys formed, has not been constrained.

Humans have driven the Earth’s freshwater cycle out of its stable state

For example, the Nile river basin has experienced exceptionally dry streamflow and wet soil moisture conditions, indicating changes driven by irrigation.
Photo Credit: Ron Porter

A new analysis of freshwater resources across the globe shows that human activity has pushed variation in the planet’s freshwater cycle well outside of its pre-industrial range. The study shows that the updated planetary boundary for freshwater change was surpassed by the mid-twentieth century. In other words, for the past century, humans have been pushing the Earth’s freshwater system far beyond the stable conditions that prevailed before industrialization. 

This is the first time that global water cycle change has been assessed over such a long timescale with an appropriate reference baseline. The findings, published in Nature Water, show that human pressures, such as dam construction, large-scale irrigation and global warming, have altered freshwater resources to such an extent that their capacity to regulate vital ecological and climatic processes is at risk.

The international research team calculated monthly streamflow and soil moisture at a spatial resolution of roughly 50x50 kilometers using data from hydrological models that combine all major human impacts on the freshwater cycle. As a baseline, they determined the conditions during the pre-industrial period (1661-1860). They then compared the industrial period (1861-2005) against this baseline.

Lake Ecosystems: Nitrogen has been underestimated

Algae growth in shallow lakes around the world is affected not only by phosphorus but also by nitrogen
Photo Credit: Liz Harrell

An ecological imbalance in a lake can usually be attributed to increased nutrient inputs. The result: increased phytoplankton growth, oxygen deficiency, toxic cyanobacterial blooms and fish kills. Until now, controls in lake management have focused primarily on phosphorus inputs to counteract this effect. Now, this dogma is shaken by a study performed by the Helmholtz Centre for Environmental Research (UFZ) in collaboration with the University of Aarhus (Denmark) and the University of Life Sciences (Estonia) and published in Nature Communications. The researchers show that nitrogen is also a critical driver for phytoplankton growth in lakes worldwide. 

The input of phosphorus and nitrogen from agricultural sources and sewage treatment plants can have a strong effect on phytoplankton growth in rivers and lakes. "However, it was previously assumed that phytoplankton growth in lakes is mostly limited and driven by the availability of phosphorus," says lead author Dr. Daniel Graeber from the UFZ. The underlying theory: If only small quantities of phosphorus are available in a lake, phytoplankton growth is correspondingly limited. In contrast, large quantities of phosphorus will massively drive phytoplankton growth. "In this explanatory model, nitrogen plays no role," says Graeber. "This is based on the fact that specific cyanobacteria in the water can bind the nitrogen contained in the air and introduce it into the lake. This would therefore preclude a long-term nitrogen deficiency in lakes." Nor could an excess supply of nitrogen promote phytoplankton growth - and therefore could not ultimately give rise to eutrophication. "This model forms the basis for lake management worldwide, where the emphasis has been on controlling phosphorus inputs to counteract lake eutrophication," explains Dr. Thomas A. Davidson, limnologist at Aarhus University and last author of the study. "Reducing phosphorus inputs repeatedly fails to prevent eutrophication. This therefore gave rise to the question of whether the water equation included yet another unknown." In its present study, the research team has now clearly identified nitrogen as such a factor, and is thus indicating new directions for inland water science (limnology) and lake management. 

Oregon State University researchers are first to see at-risk bat flying over open ocean

Hoary bat at sea.
Photo Credit: Courtesy of Will Kennerley / the MOSAIC Project.

On a research cruise focused on marine mammals and seabirds, Oregon State University scientists earned an unexpected bonus: The first-ever documented sighting of a hoary bat flying over the open ocean.

The bat was seen in the Humboldt Wind Energy Area about 30 miles off the northern California coast; the Humboldt area has been leased for potential offshore energy development, and the hoary bat is the species of bat most frequently found dead at wind power facilities on land.

OSU faculty research assistant Will Kennerley, the first to see the bat, and colleagues documented the sighting with a paper in the Journal of North American Bat Research. The bat was spotted just after 1 p.m. on Oct. 3, 2022, in observing conditions rated as excellent.

“I have spent a lot of time at sea in all oceans of the world, and I’ve seen a lot of amazing things,” said Lisa Ballance, director of OSU’s Marine Mammal Institute. “A hoary bat was a first for all of us. It’s a reminder of the wonder of nature, and of its vulnerability.”

Scientists develop novel RNA- or DNA-based substances to protect plants from viruses

The new active ingredients can be used to protect plants against viruses.
Photo Credit: Uni Halle / Markus Scholz

Individually tailored RNA or DNA-based molecules are able to reliably fight off viral infections in plants, according to a new study by the Martin Luther University Halle-Wittenberg (MLU), which was published in the International Journal of Molecular Sciences. The researchers were able to fend off a common virus using the new active substances in up to 90 per cent of cases. They also developed a method for finding substances tailored specifically to the virus. The team has now patented the method.

During a viral infection, the plant’s cells are hijacked by the virus to multiply itself. Key products of this process are viral RNA molecules that serve as blueprints for the production of proteins. "A virus cannot reproduce without producing its proteins," explains Professor Sven-Erik Behrens from the Institute of Biochemistry and Biotechnology at MLU. For years, his team has been working on ways to disrupt this process and degrade the viral RNA molecules inside the cells. 

In the new study, the researchers describe how this can be achieved using the so-called "antisense" method. It relies on short, synthetically produced DNA molecules known as antisense oligonucleotides (ASOs). In the plant cells, the ASOs direct cellular enzymes acting as scissors towards the foreign RNA so they can degrade it. "For this process to work, it is crucial to identify a suitable target structure in the viral RNA which the enzyme scissors can attach to," explains Behrens. However, finding those accessible sites is really tricky: most potential target RNA molecules have a very complex structure, and they are also masked by other cell components. "This makes it even more difficult to attack them directly," says Behrens.