Deep ocean currents around Antarctica headed for collapse

Direct measurements taken from the deep ocean have established that warming is already underway.
Photo Credit: Pixabay

Antarctic circulation could slow by more than 40 per cent over the next three decades, with significant implications for oceans and the climate.

The deep ocean circulation that forms around Antarctica could be headed for collapse, say scientists.

Such a decline would stagnate the bottom of the oceans and affect climate and marine ecosystems for centuries to come.

The results are detailed in a new study coordinated by Scientia Professor Matthew England, Deputy Director of the ARC Centre for Excellence in Antarctic Science (ACEAS) at UNSW Sydney. The work, published today in Nature, includes lead author Dr Qian Li – formerly from UNSW and now at the Massachusetts Institute of Technology (MIT) – as well as co-authors from the Australian National University (ANU) and CSIRO.

Cold water that sinks near Antarctica drives the deepest flow of the overturning circulation – a network of currents that spans the world’s oceans. The overturning carries heat, carbon, oxygen and nutrients around the globe. This influences climate, sea level and the productivity of marine ecosystems. 

Drug overdose fatalities among US older adults has quadrupled over 20 years

Photo Credit: Christina Victoria Craft

Overdose mortality among people age 65 and older quadrupled over 20 years, suggesting the need for greater mental health and substance use disorder policies addressed at curbing the trend, a new research paper finds.

The deaths stemmed from both suicides and accidental overdoses, with nearly three-fourths of the unintended fatalities involving illicit drugs such as synthetic opioids like fentanyl, heroin, cocaine, and methamphetamines.  Prescription opioids, antidepressants, benzodiazepines, antiepileptics and sedatives were used in 67% of intentional overdoses.

“The dramatic rise in overdose fatalities among adults over 65 years of age in the past two decades underscores how important it is for clinicians and policymakers to think of overdose as a problem across the lifespan,” said co-author Chelsea Shover, assistant professor of medicine in the division of general internal medicine and health services research at the David Geffen School of Medicine at UCLA. “Updating Medicare to cover evidence-based treatment for substance use disorders is crucial, as is providing harm reduction supplies such as naloxone to older adults.”

Mimicking biological enzymes may be key to hydrogen fuel production

Nickel-iron hydrogenase, described by researchers as “one of nature’s most complicated and beautiful enzymes,” may be crucial in the world’s push toward a renewable energy economy. 
Illustration Credit: Courtesy Mirica group

An ancient biological enzyme known as nickel-iron hydrogenase may play a key role in producing hydrogen for a renewables-based energy economy. Careful study of the enzyme has led chemists from the University of Illinois Urbana-Champaign to design a synthetic molecule that mimics the hydrogen gas-producing chemical reaction performed by the enzyme.

The researchers reported their findings in the journal Nature Communications. 

Currently, industrial hydrogen is usually produced by separating hydrogen gas molecules from oxygen atoms in water using a process called electrolysis. To boost this chemical reaction in the industrial setting, platinum metal is used as a catalyst in the cathodes that direct the reaction. However, many studies have shown that the expense and rarity of platinum make it unattractive as the world pushes toward more environmentally sound energy sources.

Rainbow Trout Subspecies Newly Named

The McCloud River Redband Trout is known as “cali sulat” in the Winnemem Wintu language, with “cali” meaning good or beautiful and “sulat” the term for trout.
Photo Credit: Steve MacMillan

The McCloud River redband trout, or O. mykiss calisulat, is newly identified as its own distinct subspecies of rainbow trout in a study from the University of California, Davis. It is the first newly identified subspecies of Pacific trout since 2008 and the youngest rainbow trout subspecies by more than 100 years.

The study, published in the journal Zootaxa, notes that fish biologists have suspected the McCloud River redband trout was its own subspecies since at least the 1970s, but only newer genetics techniques — including genomewide DNA sequencing — allowed the UC Davis-led team to tease the puzzle apart and confirm it as a subspecies.

Northern California’s McCloud River originates from spring-fed streams near Mount Shasta before passing over a series of waterfalls, the McCloud Falls. The waterfalls are impassable to upstream movement of fishes and divide the Upper McCloud River from the Lower McCloud River.

The McCloud River redband trout is the only known native fish found in the Upper McCloud Basin.

“It’s persisted so long in isolation,” said lead author Matthew “Mac” Campbell, a research affiliate with the Department of Animal Science’s Genomic Variation Laboratory. “They’ve survived in glacial refugia during the Pleistocene era and have been above those waterfalls for at least 10,000 years.”

Cell mapping and ‘mini placentas’ give new insights into human pregnancy

Cells of the placenta 
Image Credit: Kenny Roberts, Wellcome Sanger Institute

Researchers from the University of Cambridge, the Wellcome Sanger Institute, the Friedrich Miescher Institute for Biomedical Research (FMI), Switzerland, EMBL’s European Bioinformatics Institute (EMBL-EBI), and collaborators, have created an in-depth picture of how the placenta develops and communicates with the uterus.

The study, published today in the journal Nature, is part of the Human Cell Atlas initiative to map every cell type in the human body. It informs and enables the development of experimental models of the human placenta.

"For the first time, we have been able to draw the full picture of how the placenta develops and describe in detail the cells involved in each of the crucial steps. This new level of insight can help us improve laboratory models to continue investigating pregnancy disorders, which cause illness and death worldwide,” said Anna Arutyunyan, co-first author at the University of Cambridge and Wellcome Sanger Institute.

The placenta is a temporary organ built by the fetus that facilitates vital functions such as fetal nutrition, oxygen and gas exchange, and protects against infections. The formation and embedding of the placenta into the uterus, known as placentation, is crucial for a successful pregnancy.

Three newly discovered sea worms that glow in the dark

 Polycirrus onibi, a newly discovered marine worm that glows in the dark was named after a creature from Japanese folklore.
Photo Credit: Naoto Jimi / Nagoya University

A research group from Nagoya University in central Japan has discovered three new species of bioluminescent polycirrus worms from different parts of Japan. Usually found in shallow water, polycirrus are small worms, known for their bioluminescence. The researchers named one of their discoveries after a ghostly yokai, a creature in Japanese folklore; another after a lantern yokai; and the other after an influential Japanese marine biologist. They published their findings in the journal Royal Society Open Science. 

Scientists have studied only a small fraction of the more than 7,000 species of luminescent organisms in the world. Research remains limited to certain species because of the existence of specimens that are difficult to classify into species. Without correct identification of the species, comparisons of different results are of limited use.  

Naoto Jimi (he/him) and Special Assistant Professor Manabu Bessho-Uehara (he/him) at Nagoya University’s Graduate School of Science, led a research group with members from AIST, Olympus Corporation, and Japan Underwater Films Corporation, that organized Polycirrus according to their diversity. They discovered three new species, all of which emit blue-violet light.   

Ancient DNA reveals entwined African and Asian ancestry along the Swahili coast of eastern Africa

Rice researchers Mary Prendergast and Jeffrey Fleisher.
Photo Credit: Brandon Martin.

A new genetic study of medieval people who lived along the Indian Ocean coast of eastern Africa — an area often called the “Swahili coast” for its language and culture — revealed that they had both African and Persian ancestry.

The results suggest that maritime trade connections long recognized by archaeologists based on imported goods and architectural influences fostered relationships between Asian merchants and African traders and their families.

“Entwined African and Asian genetic roots of medieval peoples of the Swahili coast” was published today in Nature. It examines genetic ancestry and cultural influences in eastern Africa by using DNA from the skeletal remains of 80 individuals who were buried in six medieval and early modern coastal towns in Kenya and Tanzania dating to the years 1250-1800 and an inland town in Kenya dating to after 1650.

Analysis of the genetic data enabled scientists to estimate that people of African and Persian ancestry began to have children together around the year 1000, centuries before the burials themselves.

How the gut creates a cozy home for beneficial microbiome species

Image Credit: Courtesy of Carnegie Institution for Science

The digestive tract of fruit flies remodels itself to accommodate beneficial microbiome species and maintain long-term stability of the gut environment, according to new research led by Carnegie’s William Ludington and Allan Spradling. Their findings are published in Nature Communications.

The gut microbiome is an ecosystem of hundreds to thousands of microbial species living within the human body. These populations affect our health, fertility, and longevity. But there is still so much to learn about how these microbial species interact with our bodies and with each other.

“Every day, we encounter, and even ingest, a diverse array of bacterial species,” explained Ludington, who has been probing microbiome acquisition and composition for several years at Carnegie. “Despite this, the gut microbiome remains relatively stable over time—a phenomenon that is maintained across many species ranging from mammals to insects.”

He, Spradling, and their collaborators wanted to determine how our guts can maintain such remarkably consistent microbiome compositions. Because the human microbiome is so complex, they studied fruit flies, which are only colonized by a handful of microbial species.

Birth of a very distant cluster of galaxies from the early Universe

This image shows the protocluster around the Spiderweb galaxy (formally known as MRC 1138-262), seen at a time when the Universe was only 3 billion years old. Most of the mass in the protocluster does not reside in the galaxies that can be seen in the centre of the image, but in the gas known as the intracluster medium (ICM). The hot gas in the ICM is shown as an overlaid blue cloud.   The hot gas was detected with the Atacama Large Millimeter/submillimeter Array (ALMA), of which ESO is a partner. As light from the cosmic microwave background –– the relic radiation from the Big Bang –– travels through the ICM, it gains energy when it interacts with the electrons in the hot gas. This is known as the Sunyaev-Zeldovich effect. By studying this effect, astronomers can infer how much hot gas resides in the ICM, and show that the Spiderweb protocluster is in the process of becoming a massive cluster held together by its own gravity. 
Full Size Image
Image Credit: ESO/Di Mascolo et al.; HST: H. Ford

Using the Atacama Large Millimeter/submillimeter Array (ALMA), of which ESO is a partner, astronomers have discovered a large reservoir of hot gas in the still-forming galaxy cluster around the Spiderweb galaxy — the most distant detection of such hot gas yet. Galaxy clusters are some of the largest objects known in the Universe and this result, published today in Nature, further reveals just how early these structures begin to form.

Galaxy clusters, as the name suggests, host a large number of galaxies — sometimes even thousands. They also contain a vast “intracluster medium” (ICM) of gas that permeates the space between the galaxies in the cluster. This gas in fact considerably outweighs the galaxies themselves. Much of the physics of galaxy clusters is well understood; however, observations of the earliest phases of formation of the ICM remain scarce.

Previously, the ICM had only been studied in fully-formed nearby galaxy clusters. Detecting the ICM in distant protoclusters — that is, still-forming galaxy clusters – would allow astronomers to catch these clusters in the early stages of formation. A team led by Luca Di Mascolo, first author of the study and researcher at the University of Trieste, Italy, were keen to detect the ICM in a protocluster from the early stages of the Universe. 

Retinoic Acid Could Be Key to Preventing Gut Infections

Brian Sheridan conducts research on CD8 T cells to investigate immune responses with the hope of laying groundwork for new therapies and vaccines. 
Photo Credit: John Griffin, Stony Brook University

A team of scientists from the Renaissance School of Medicine (RSOM) at Stony Brook University have identified a distinct role of retinoic acid, a metabolite of vitamin A, during the immune response of the gut. This finding, detailed in a paper published in the Journal of Experimental Medicine, and highlighted in a broader piece in the journal, could help lead to ways to control the retinoic acid response and therefore could be used as a therapy or for vaccine development against infection or even to treat GI tumors.

Led by Brian Sheridan, associate professor in the Department of Microbiology and Immunology and the Center for Infectious Diseases, the study involves basic research that centers on unraveling the factors that control the generation of cytotoxic memory CD8 T cells, which are an important arm of the body’s anti-pathogen immune response as they kill pathogen-infected cells and produce anti-pathogen cytokines. In fact, memory CD8 T cells provide long-lived and frontline protection at barrier tissues, highlighting their importance in vaccine design.

To date, scientists have known that retinoic acid in the gut-draining lymph nodes promotes effector CD8 T cell migration to the intestines, enhancing the immune response. Additionally, vitamin A deficiency is associated with increased infections and poor vaccine efficiency.