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Imaging reveals bacterial symbionts in the ovaries of tiny, aquatic crustaceans

Marine Biological Laboratory

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Ostracod ovarium with endosymbiotic bacteria (Cardinium) in magenta.

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Credit: Schön and Chimileski et al., Proc. Royal Soc. B, 2025

By Meghan Willcoxon

WOODS HOLE, Mass. -- Researchers at the Marine Biological Laboratory (MBL) have imaged a heritable form of bacterial symbiosis inside the reproductive system of tiny crustaceans known as ostracods. Led by MBL Whitman Scientist Isa Schön and MBL Research Scientist Scott Chimileski, the study is published this week in Proceedings of the Royal Society B.

Ostracods, sometimes called seed shrimp, are nearly microscopic, aquatic organisms, inhabiting all types of marine and freshwater environments. Using fluorescence microscopy, the team discovered that bacteria from the genus Cardinium live inside the egg cells and tissues of ostracod ovaries.

In a “true hallmark of endosymbiosis,” said Schön, the bacteria are transmitted from mothers to offspring. These findings suggest that the bacteria manipulate host asexual reproduction.

While symbiosis with bacteria is an emerging research topic for ostracods, endosymbiotic bacteria have been studied intensely in other arthropods, such as insects.

Mosquitos, Chimileski said, are known to harbor endosymbiotic bacteria from the genus Wolbachia. These bacteria are involved in mosquito reproduction, and can be used to curb the spread of mosquito-borne illnesses. By finding a parallel process in ostracods, scientists can investigate endosymbiosis in an aquatic arthropod that makes up a key part of the food web.

A Multi-Year Collaboration

The striking ostracod-bacteria visualizations were the result of a multi-year, multi-lab collaboration between MBL scientists and affiliates.

Schön, a senior scientist at Royal Belgian Institute of Natural Sciences, came to the MBL as a Whitman Fellow in 2022 to develop ostracods as a new research organism. This work helps to counteract the fact that most biological research originates from a handful of model organisms such as fruit flies and mice. “There are endless discoveries yet to be made across the biodiverse animal kingdom on this planet,” said Chimileski.

To confirm that symbiotic bacteria are present inside ostracods – and to locate precisely where they may be – the team needed to label the bacteria and use confocal microscopes at the MBL’s Central Microscopy Facility to image the animals at fine, micrometer-size scales. Schön and her colleague, Koen Martens, an evolutionary biologist at Royal Belgian Institute of Natural Sciences, teamed up with Chimileski and Jessica Mark Welch of ADA Forsyth Institute to adapt such methods. Chimileski and Mark Welch are microbiologists with expertise in visualizing the spatial patterns of bacteria in the human mouth and other microbiomes.

“This study establishes non-marine ostracods as the first fully aquatic host system for Cardinium and reinforces their value as models for evolutionary research,” said Schön.

Close-up of Endosymbiotic Bacteria Within Ostracod Egg

Close-up detail of endosymbiotic bacteria cells (Cardinium, in red) within an ostracod egg. Credit:  Schön and Chimileski, et al., Proc. Royal Soc. B, 2025

Credit

Schön and Chimileski, et al., Proc. Royal Soc. B, 2025

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The Marine Biological Laboratory (MBL) is dedicated to scientific discovery – exploring fundamental biology, understanding marine biodiversity and the environment, and informing the human condition through research and education. Founded in Woods Hole, Massachusetts in 1888, the MBL is a private, nonprofit institution and an affiliate of the University of Chicago.

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Journal

Proceedings of the Royal Society B Biological Sciences

DOI

10.1098/rspb.2025.1193 

Method of Research

Experimental study

Subject of Research

Animals

Article Title

Vertical transmission of Cardinium bacteria in parthenogenetic non-marine ostracods (Crustacea)

Article Publication Date

12-Nov-2025

 

Clinical trial in Africa finds single-dose malaria treatment combining four existing drugs as effective as more onerous multi-day, multi-dose regimen

Research advance from Gabon presented at the American Society of Tropical Medicine and Hygiene Annual Meeting addresses threat of malaria parasite drug resistance

American Society of Tropical Medicine & Hygiene

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TORONTO (November 12, 2025) —Hundreds of malaria patients participating in a Phase 3 clinical trial in Gabon in West Africa were cured via a single dose of a treatment that utilizes four widely available malaria drugs, according to a new study presented today at the Annual Meeting of the American Society of Tropical Medicine and Hygiene (ASTMH).

The advance addresses a pair of problems that have contributed to a stalled fight against a disease that each year kills about 600,000 people: the alarming rise of drug-resistant malaria and the fact that a third or more of malaria patients fail to complete the standard three-day course of treatment, which can both encourage drug resistance and allow curable cases to intensify. 

“We found that our single-dose treatment was just as effective as the standard course that typically requires taking six doses spaced out over three days, which many patients never complete,” said Ghyslain Mombo-Ngoma, MD, PhD, lead author of the study and head of clinical operations at the Medical Research Center of Lambaréné, Gabon (known by its French acronym CERMEL).

He noted the single-dose treatment combining sulfadoxine, pyrimethamine, artesunate and pyronaridine (SPAP) may be more effective against drug-resistant parasites than standard therapies because the novel combination of four medicines—versus two drugs typically used in conventional treatments—targets four different vulnerabilities in the malaria parasite. Mombo-Ngoma said forcing a pathogen to fight a multi-front battle has been used to counter drug resistant tuberculosis and is of growing interest to malaria experts. Meanwhile, he said a single-dose option for treating malaria addresses the problem of resistance emerging in patients that don’t complete their full course of medicines—while also curing cases that, if insufficiently medicated, can allow malaria to persist and potentially cause life-threatening complications.

There is an urgent need for new ways to treat malaria patients because in sub-Saharan Africa, which accounts for 95% of the world’s malaria infections and deaths, the fight against the disease has hit a plateau. After falling dramatically from 2000 to 2015, malaria infections and deaths, which mainly occur in children under 5 years old, have increased. The most recent figures available from the World Health Organization show that in 2023, there were 263 million cases and 597,000 deaths, compared with 2016 levels of 216 million cases and 445,000 deaths. 

Along with funding threats, a key impediment to rejuvenating the fight against malaria is that parasites are developing at least partial resistance to treatments that combine artemisinin-based malaria drugs (once hailed as a major breakthrough against malaria) with one other medicine.

“Another challenge is that artemisinin combination therapies (ACTs) must be taken for three days to clear parasites from infected patients, and a third or more of malaria patients don’t complete the full course,” Mombo-Ngoma said. He said this failure can allow a large number of parasites to linger in the body, posing the risk that they could continue to multiply and cause severe disease, while also giving them time to develop mutations that can overcome ACTs.

One Dose to Fight Two Malaria Foes: Treatment Adherence and Drug Resistance

Mombo-Ngoma and his colleagues, who include Peter Kremsner, MD, PhD, director of the Institute of Tropical Medicine at Germany’s University of Tübingen, recently published an analysis in the Malaria Journal that made the case for fighting the twin problems of treatment adherence and drug resistance by attempting to cure patients with a single dose comprised of several different malaria medications, all of them easily accessible in sub-Saharan Africa. They also have been working to test the approach in patients. From May 2024 to October 2025, they led a team that conducted a trial in Gabon involving treating more than 1,000 patients, half of them under 10 years old, who were fighting what is known as “uncomplicated malaria.” That means they were sick, but they were not yet suffering severe life-threatening symptoms.  

A little over half of the patients (539) were treated with a regimen that involved administering a single dose consisting of two different malaria “combination” medicines, which together involve four different drugs. One is known as SP, because it utilizes the drugs sulfadoxine and pyrimethamine, and the other is called AP, because it employs artesunate (which is a type of artemisinin) alongside pyronaridine. The rest of the patients (442) received a widely used ACT that combines the artemisinin drug artemether with lumefantrine, aka AL, which requires taking six doses over three days.

Blood tests conducted 28 days after the treatments showed that 93% of patients who received the single-dose cure were free of parasites compared to 90% who got the standard three-day course—meaning they were essentially equally effective. Mombo-Ngoma said there were no reports of study drug related serious adverse events in any of the patients.

“Another key advantage is that our single-dose cure was accomplished with drugs that are currently available to malaria treatment programs across Africa—and relatively affordable as well,” he said. “One of the medications, the sulfadoxine-pyrimethamine (SP) combination, is a generic drug already manufactured in several African countries, while artesunate-pyronaridine (AP) is not yet available as a generic but will be by early 2026.”

Mombo-Ngoma said there are already discussions underway with a drug manufacturer to produce SP and AP as a single capsule or sachet (a packet of pills). He also said malaria researchers in Mali, Ghana, Kenya and Mozambique have expressed interest in testing the single-dose approach.

The evidence supporting a single-dose cure that could at least reduce the threat of drug resistance is arriving at a time of encouraging progress in developing new compounds capable of defeating drug-resistant parasites. Mombo-Ngoma noted that while there is hope on the horizon, even in a best-case scenario, it will still take several years for the most advanced of these compounds to become widely available in Africa.

“I’m a malaria researcher, but I’m also a doctor treating a lot of malaria patients, and I need new options now,” he said. “What I hope is that, if we continue to have success with this single-dose cure, it can serve as a bridge to the new treatments now under development—something we can deploy very soon while we await the arrival of other options.”

“It’s exciting to see our members pursuing innovative ways of fighting drug-resistant malaria while also seeking solutions to treatment-adherence challenges, which is a pervasive problem in the management of many diseases,” said ASTMH President David Fidock, PhD, who heads a group of experts on antimalarial drug resistance that advises the WHO Malaria and Neglected Tropical Diseases Program. “This study is also a reminder that, at a time when the entire field of global health is facing enormous headwinds, ASTMH members are keeping their focus on research that can support better health for millions of people in low- and middle-income countries.” 

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About the American Society of Tropical Medicine and Hygiene

The American Society of Tropical Medicine and Hygiene, founded in 1903, is the largest international scientific organization of experts dedicated to reducing the worldwide burden of tropical infectious diseases and improving global health. It accomplishes this through generating and sharing scientific evidence, informing health policies and practices, fostering career development, recognizing excellence, and advocating for investment in tropical medicine/global health research. For more information, visit astmh.org.

New study uncovers difficulties accessing wheelchairs through insurance

FOR PROFIT HEALTHCARE

University of Minnesota Medical School

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MINNEAPOLIS/ST. PAUL (11/12/2025) — Published today in Mayo Clinic Proceedings, a University of Minnesota Medical School research team found that access to wheelchairs through Medicare-listed suppliers is inconsistent and often challenging.

Using a secret-shopper approach where researchers posed as patients seeking care, the research team evaluated insurance acceptance, administrative requirements, delivery timelines and costs in two urban zip codes. Only one-half of suppliers with wheelchairs in supply accepted Medicare, and many imposed additional documentation requirements. Among these suppliers, nearly half reported it would take several weeks before wheelchair approval and delivery. 

For those paying cash, the median wheelchair cost was $300. Most suppliers accepting Medicare did not mention Medicare's rent-to-own program for wheelchairs.

“Patients attempting to access a wheelchair through suppliers listed in the Medicare directory face administrative and logistical challenges, highlighting the need for urgent policy form to assist vulnerable older adults in accessing critical medical equipment,” said Arjun Gupta, MBBS, an assistant professor at the University of Minnesota Medical School. “Greater oversight of supplier practices, clearer standards and improved directory accuracy are needed to reduce administrative and financial barriers for beneficiaries.”

Further studies are suggested to expand to rural and diverse geographic settings, evaluate the accuracy of Medicare’s supplier directory and assess the real-world impact of access barriers on patients and caregivers.

“Patients with mobility issues are often forced to navigate a maze of phone calls, insurance rejections and paperwork just to get a basic wheelchair. These delays and barriers leave many with no choice but to pay out-of-pocket through online marketplaces or other sources— this is an unacceptable burden on those already facing health problems,” said Dr. Gupta, who is also an oncologist with M Health Fairview.

This research was funded by the Pancreatic Cancer Action Network.

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About the University of Minnesota Medical School
The University of Minnesota Medical School is at the forefront of learning and discovery, transforming medical care and educating the next generation of physicians. Our graduates and faculty produce high-impact biomedical research and advance the practice of medicine. We acknowledge that the U of M Medical School is located on traditional, ancestral and contemporary lands of the Dakota and the Ojibwe, and scores of other Indigenous people, and we affirm our commitment to tribal communities and their sovereignty as we seek to improve and strengthen our relations with tribal nations. Learn more at med.umn.edu.

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Journal

Mayo Clinic Proceedings

DOI

10.1016/j.mayocp.2025.09.009 

Method of Research

Data/statistical analysis

Subject of Research

People

Article Title

Simulated Experiences in Accessing Standard Manual Wheelchairs Through Medicare-Listed Suppliers

Article Publication Date

12-Nov-2025

 

Earth’s largest modern crater discovered in Southern China

The Jinlin crater is 900 meters in diameter and dates to Earth’s current geological epoch.

American Institute of Physics

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image: 

A panoramic aerial drone image of the Jinlin crater with the approximate location of the crater rim labeled, with an insert of the crater floor, which shows a mix of granite weathered soil and granite fragments. The yellow ruler is 20 centimeters long.

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Credit: Ming Chen

WASHINGTON, Nov. 12, 2025 – A newly discovered, remarkably well-preserved impact crater is shedding fresh light on how extraterrestrial bodies collide with Earth.

In the journal Matter and Radiation at Extremes, by AIP Publishing, researchers from Shanghai and Guangzhou, China, report the discovery of the Jinlin crater: an impact structure nestled on a hillside and preserved within a thick granite weathering crust.

Located in Zhaoqing, Guangdong Province, China, it is one of only about 200 identified craters worldwide and is very young in geological years. Based on measurements of nearby soil erosion, it likely formed during the early-to-mid Holocene — our current geological epoch, which began at the end of the last ice age about 11,700 years ago. With a diameter of 900 meters, it is the largest known impact crater from this era — far exceeding Russia’s 300-meter Macha crater, previously the largest known Holocene impact structure.

“This discovery shows that the scale of impacts of small extraterrestrial objects on the Earth in the Holocene is far greater than previously recorded,” said author Ming Chen.

In this case, the “small” impactor in question was a meteorite rather than a comet, which would have left a crater at least 10 kilometers wide. However, the research team has not yet determined whether the meteorite was made of iron or stone.

One of the most surprising traits of this crater is how well-preserved it is, especially given the region’s monsoons, heavy rainfall, and high humidity — all conditions that accelerate erosion. Within the granite layers that help to protect and preserve its impact structure, the researchers found many pieces of quartz with unique microfeatures, called planar deformation features, that geologists use as evidence of some type of impacts.

“On the Earth, the formation of planar deformation features in quartz is only from the intense shockwaves generated by celestial body impacts, and its formation pressure ranges from 10 to 35 gigapascals, which is a shock effect that cannot be produced by any geological process of the Earth itself,” said Chen.

It is generally believed that throughout Earth’s history, every point on its surface has faced roughly equal odds of being struck by an extraterrestrial object. However, geological differences mean that the historical footprints of these impacts eroded at varying rates, and some have fully disappeared. This makes the Jinlin Crater’s discovery particularly significant.

“The impact crater is a true record of Earth’s impact history,” said Chen. “The discovery of the Earth impact crater can provide us with a more objective basis for understanding the distribution, geological evolution, and impact history and regulation of small extraterrestrial bodies.”

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The article “Jinlin crater, Guangdong Province, China: Impact origin confirmed” is authored by Ming Chen, Dayong Tan, Wenge Yang, Ho-Kwang Mao, Xiande Xie, Feng Yin, and Jinfu Shu. It was published in Matter and Radiation at Extremes and can be accessed at https://doi.org/10.1063/5.0301625.

ABOUT THE JOURNAL

Matter and Radiation at Extremes (MRE), published by China Academy of Engineering Physics (CAEP), is committed to the publication of original research and comprehensive and in-depth review papers in all areas of experimental and theoretical physics on matter and radiation at extremes. MRE aims to provide a peer-reviewed Open-Access platform for the international physics community and promote worldwide dissemination of the latest and best research in related fields. See https://pubs.aip.org/aip/mre.

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Journal

Matter and Radiation at Extremes

DOI

10.1063/5.0301625 

Article Title

Jinlin crater, Guangdong Province, China: Impact origin confirmed