The Donnan Potential, Revealed at Last

Staff scientist Ethan Crumlin at Berkeley Lab's Advanced Light Source.
Photo Credit: Marilyn Sargent/Berkeley Lab

The Donnan electric potential arises from an imbalance of charges at the interface of a charged membrane and a liquid, and for more than a century it has stubbornly eluded direct measurement. Many researchers have even written off such a measurement as impossible.

But that era, at last, has ended. With a tool that’s conventionally used to probe the chemical composition of materials, scientists at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) recently led the first direct measurement of the Donnan potential.

“We were naïve enough to believe we could do the impossible.”

Ethan Crumlin, Berkeley Lab staff scientist, Advanced Light Source (ALS)

Crumlin and his collaborators recently reported the measurement in Nature Communications.

Such a measurement could yield new insights in many areas that focus on membranes. The Donnan potential plays a critical role in transporting ions through a cellular membrane, for example, which ties it to biological functions ranging from muscle contractions to neural signaling. Ion exchange membranes are also important in energy storage strategies and water purification technologies.

Alien Planet Found Spiraling to its Doom around an Aging Star

An artist's concept of the Kepler-1658 system. Kepler-1658b, orbiting with a period of just 3.8 days, was the first exoplanet candidate discovered by Kepler. 
Illustration Credit: Gabriel Perez Diaz/Instituto de Astrofísica de Canarias

For the first time, astronomers have spotted an exoplanet whose orbit is decaying around an evolved, or older, host star. The stricken world appears destined to spiral closer and closer to its maturing star until collision and ultimate obliteration.

The discovery offers new insights into the long-winded process of planetary orbital decay by providing the first look at a system at this late stage of evolution. Death-by-star is a fate thought to await many worlds and could be the Earth's ultimate adios billions of years from now as our Sun grows older.

"We've previously detected evidence for exoplanets inspiraling toward their stars, but we have never before seen such a planet around an evolved star," says Shreyas Vissapragada, a 51 Pegasi b Fellow at the Center for Astrophysics | Harvard & Smithsonian and lead author of a new study describing the results. "Theory predicts that evolved stars are very effective at sapping energy from their planets' orbits, and now we can test those theories with observations."

Mouse pups cry for help most urgently while active

Mouse pups produce ultrasonic vocalizations, called isolation USVs, when they are separated from the nest. It’s a survival mechanism – baby mice need their parents to regulate their temperature and feed them – that diminishes with age.

But before the USV reflex peters out around 20 days after birth, the rate at which mouse pups cry varies a lot, even within the same individual at the same age, according to Katherine Tschida, the Mary Armstrong Meduski ’80 Assistant Professor of psychology in the College of Arts and Sciences. Exploring this variation, researchers in the Tschida Lab found a link between mouse pup USV rates and their activity levels; the greater amount of body movement, the higher the rate of vocalizations. The connection is important for understanding mouse neural circuitry and development and provides a richer understanding of behavioral differences in mouse models of communication disorders, including autism spectrum disorder (ASD.)

“Rates of Ultrasonic Vocalizations are More Strongly Related Than Acoustic Features to Non-vocal Behaviors in Mouse Pups” was published Dec. 19 in Frontiers in Behavioral Neuroscience. Tschida and doctoral student Nicole Pranic are first authors. Contributions were made by Thomas Cleland, professor of psychology; Chen Yang, programmer and analyst in the Cleland Lab; and by Caroline Kornbrek ’23.

Scientists from NUS and NUHS identify predictive blood biomarker for cognitive impairment and dementia

Prof Barry Halliwell (left) and Dr Irwin Cheah (right), together with their collaborators from the National University Health System, have discovered that low levels of ergothioneine in blood plasma may predict an increased risk of cognitive impairment and dementia.
Photo Credit: National University of Singapore

Identification of elderly persons at risk of developing cognitive impairment and dementia could be made possible by examining ergothioneine levels in the blood

A recent study by a team comprising researchers from the National University of Singapore (NUS) and the National University Health System (NUHS) revealed that low levels of ergothioneine (ET) in blood plasma may predict an increased risk of cognitive impairment and dementia, suggesting possible therapeutic or early screening measures for cognitive impairment and dementia in the elderly.

The research teams were led by Professor Barry Halliwell from the Department of Biochemistry under the NUS Yong Loo Lin School of Medicine and Associate Professor Christopher Chen and Dr Mitchell Lai from the Memory, Ageing and Cognition Centre under NUHS. The results of their most recent study were published in the scientific journal Antioxidants.

Samples From Asteroid Ryugu Help Us Learn About Earth's Origins

The elemental composition of the Earth comes from its fiery past, through accretion of various solar system objects. New samples collected by the Hayabusa2 space mission provide insight into the origins of moderately volatile elements such as zinc and copper. Tokyo Tech researchers have linked the material from the Cb-type asteroid, Ryugu, to the elemental composition of the Earth. Their results suggest that Ryugu-type material played a significant role in the genetic heritage of the Earth's elemental composition.

Understanding the origins of Earth's elemental composition offers a glimpse into the history of our planet. One way to learn about this is to investigate the meteorites that would have similar composition with materials that contributed to the accretion of planet Earth in its early development. Meteorites are divided into multiple classes based on their composition. The most primitive and common of these classes includes chondrites, which further includes carbonaceous chondrites (CCs). Of these, Ivuna-type (CI) CCs have an elemental composition that is nearly identical with that of the solar photosphere, which therefore can be used as a key reference for understanding how early solar system processes shaped planets and their building blocks. The Hayabusa2 spacecraft's mission was to collect samples from the Cb-type asteroid (162173), Ryugu. As the elemental composition of returned Ryugu samples is unaffected by further terrestrial processes, the two successful sampling events on Ryugu offer a plethora of unprecedented information.

Critical illness myopathy common condition in intensive care patients

Lars Larsson performing experiments on the ICU models.
Photo Credit: Ya Wen

Critical illness myopathy (CIM) is a common complication affecting ventilator-treated intensive care patients, which can lead to increased mortality/morbidity, prolonged hospital care, impaired patient quality of life, and increased healthcare costs. reported molecular pathogenesis of CIM during prolonged ICU stay, and potential diagnostic biomarkers and therapeutic targets. The study was recently published in Journal of Cachexia, Sarcopenia and Muscle.

Over the past 65 years, intensive care units (ICUs) have undergone a significant development that has resulted in improved survival rates. But life-saving efforts are also accompanied by negative consequences for ICU patients, affecting skeletal muscle systems, including the critical illness myopathy (CIM) with muscle wasting and paralysis/paresis. The incidence of CIM is about 30% among ICU patients, and almost 100% in neuro-ICU patients exposed to prolonged controlled mechanical ventilation. Moreover, the negative consequences have become increasingly apparent during the COVID-19 pandemic.

New study finds logged tropical forests are surprisingly vibrant and need protection

Logged tropical forests are surprisingly vibrant and need protection.
Photo Credit: Zoe G Davies

A new study by researchers at the University of Oxford, finds that logged rainforests are treasure-troves of healthy ecological function and should not be written off for oil palm plantations.

The study examines the flow of ecological energy across old-growth forests, logged forests and oil palm

Surveys mammal and bird species across these landscapes to calculate food energetic pathways: how photosynthetic energy cascades from sunlight to be distributed among organisms

Relative to energy flow in old-growth forests, study finds 2.5 times more total energy flows in logged forests

The study findings question the use of the word “degraded” to describe logged tropical forests

Why aren’t all black bears black?

Cinnamon Black Bear
Resized Image using AI by SFLORG
Photo Credit: Appalachian Encounters / CC BY 2.0

Sometimes a name is just a name. Take bears, for example. In Yellowstone National Park, black bears outnumber their brownish-colored grizzly bear cousins, and in coastal areas of the Pacific Northwest, if someone says “brown bear,” they mean grizzly bear. But not all brown bears are grizzly bears.

American black bears (Ursus americanus), which one would logically assume are, well, black, actually come in a range of colors, including brown (also known as cinnamon), blond, or bluish-grey. Others have coats that are a mixture of several colors. So, how do you tell a cinnamon-colored Ursus americanus from its brown (grizzly) Ursus arctos cousin? Differences in body shape and size can be subtle. One hypothesis for the cinnamon color of Ursus americanus is that it mimics the appearance of a grizzly bear, helping with camouflage or defense.

Now, researchers at the HudsonAlpha Institute for Biotechnology, the University of Memphis, and the University of Pennsylvania, have discovered what causes the cinnamon color, which sheds some light on this color confusion.

UCLA-developed soft brain probe could be a boon for depression research

 Illustration of the soft probe with aptamer biosensors implanted in the brain.
Illustration Credit: Zhao, et al., 2022

Anyone familiar with antidepressants like Prozac or Wellbutrin knows that these drugs boost levels of neurotransmitters in the brain like serotonin and dopamine, which are known to play an important role in mood and behavior.

It might come as a surprise, then, that scientists still have very little data about the specific relationship between neurotransmitters — chemicals that relay messages from one brain cell to others — and our psychological states. Simply put, monitoring fluctuations of these neurochemicals in living brains has proved a persistent challenge.

Now, for the first time, UCLA scientists have attached nanoscale biochemical sensors, which are tuned to identify specific neurotransmitters, to a soft, implantable brain probe in order to continuously monitor these chemicals in real time. The new brain probe, described in a paper published in ACS Sensors, would allow scientists to track neurotransmitters in laboratory animals — and, ultimately, humans — during their day-to-day activities.

Researchers have identified the origins of a serious illness in children

Egle Kvedaraite, doctor and researcher.
Photo Credit: Sebastien Teissier.

The origins of the serious cancer-like disease LCH have been identified by researchers from Karolinska Institutet in collaboration with Karolinska University Hospital. The findings presented in Science Immunology may lead to new, targeted treatments.

Langerhans’ Cell Histiocytosis (LCH) is a serious type of cancer-like disease that mainly affects children and can be fatal in severe cases. About five to ten children get the disease in Sweden every year, usually before the age of ten.  

The immune cells are affected by cancer mutations

LCH is a disease in which the cancer mutation occurs in the immune cells, which otherwise have the task of detecting and eliminating cancer cells.