Gamma rays quickly toughen nitrogen‑fixing bacteria

QST team pairs experimental evolution with controlled gamma irradiation to create heat‑tolerant biofertilizer strains in weeks, pointing to faster, greener production for food, pharma, and biofuels

The National Institutes for Quantum Science and Technology

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Heat-tolerant mutant lines of rhizobia obtained by experimental evolution combined with repeated mutagenesis with gamma rays

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Credit: Dr. Yoshihiro Hase from the National Institutes for Quantum Science and Technology, Japan

Takasaki, Japan — Heat‑resilient biofertilizers could help crops cope with rising temperatures but engineering them has been slow and uncertain. A new study at the National Institutes for Quantum Science and Technology (QST) shows that pairing experimental evolution with controlled gamma‑ray mutagenesis can accelerate the path to heat‑tolerant nitrogen‑fixing bacteria, shortening development timelines and opening practical routes to more reliable, climate‑ready microbial products for agriculture, food processing, pharmaceuticals, and biofuel production. The study was made available online on November 19, 2025, and published in Volume 831 on July, 01, 2025, in the Mutation Research - Fundamental and Molecular Mechanisms of Mutagenesis journal.

The team focused on Bradyrhizobium diazoefficiens USDA110, a workhorse bacterium used to help soybean and other legumes capture nitrogen. While the wild-type grows best at around 32–34 °C and stalls at ~36 °C, QST researchers raised culture temperatures stepwise from 34 °C to 37 °C over 76–83 days and irradiated populations ten times at specific doses, then selected the lines that continued to form robust colonies at 36 °C.

A clear “sweet spot” emerged: around 40 Gy produced the greatest number of stable, heat‑tolerant lines, whereas higher doses (80–120 Gy) initially yielded more tolerant lines but with smaller colonies and traits that faded when selection relaxed, consistent with an excess of deleterious mutations. In practical terms, the method lets researchers tune the mutation load to favor beneficial changes while preserving overall fitness.

Genomic analyses of the top performers revealed changes in two core genes across independently evolved lines: the 16S rRNA gene, central to the protein‑making machinery, and rpoC, which encodes the β subunit of RNA polymerase. Convergent mutations in such essential systems point to mechanisms that help bacterial transcription and translation continue smoothly under heat stress—precisely the behaviors industry needs in high‑temperature processes.

“By combining adaptive laboratory evolution with precisely repeated doses of gamma rays, we shortened the path to robust, heat‑tolerant bacteria from months or years to just weeks,” said Dr. Yoshihiro Hase, project leader at the Takasaki Institute for Advanced Quantum Science (TIAQ), QST. “It’s a practical lever for making biofertilizers more reliable in hotter fields and bioreactors.”

“This controllable mutagenesis avoids transgenic modifications and can be tuned to maximize beneficial changes while limiting genetic load,” added Dr. Katsuya Satoh, senior principal researcher　at TIAQ. “We see a route that industry can adopt safely to boost resilience and productivity.”

Beyond agriculture, the approach could be generalized to yeasts, bacteria, and microalgae used in food processing, therapeutic manufacturing, and biofuel production—helping deliver high‑quality products at lower environmental cost. In the long term, QST anticipates ultra‑low‑cost microalgal cultivation and other heat‑tolerant platforms that contribute to food and energy security.

 

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Reference
DOI: 10.1016/j.mrfmmm.2025.111919

 

About National Institutes for Quantum Science and Technology, Japan
The National Institutes for Quantum Science and Technology (QST) was established in April 2016 to promote quantum science and technology in a comprehensive and integrated manner. The new organization was formed from the merger of the National Institute of Radiological Sciences (NIRS) with certain operations that were previously undertaken by the Japan Atomic Energy Agency (JAEA).

QST is committed to advancing quantum science and technology, creating world-leading research and development platforms, and exploring new fields, thereby achieving significant academic, social, and economic impacts.

Website: https://www.qst.go.jp/site/qst-english/

 

About Dr. Yoshihiro Hase
Dr. Yoshihiro Hase works at the Takasaki Institute for Advanced Quantum Science, National Institutes for Quantum Science and Technology, Japan. His research focuses on mutagenesis by quantum beams in plants and bacteria and he has published more than 70 papers on these topics, which have received more than 1,600 citations.

 

Funding information
This study was partially supported by The Canon Foundation.

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Journal

Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis

DOI

10.1016/j.mrfmmm.2025.111919 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Repeated artificial mutagenesis of Bradyrhizobium diazoefficiens by gamma irradiation accelerates the acquisition of high-temperature tolerance

 

This new tool could tell us how consciousness works

Researchers propose a roadmap for using transcranial focused ultrasound, a noninvasive way to stimulate the brain and see how it functions

Massachusetts Institute of Technology

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Consciousness is famously a “hard problem” of science: We don’t precisely know how the physical matter in our brains translates into thoughts, sensations, and feelings. But an emerging research tool called transcranial focused ultrasound may enable researchers to learn more about the phenomenon.

The technology has entered use in recent years, but it isn’t yet fully integrated into research. Now, two MIT researchers are planning experiments with it, and have published a new paper they term a “roadmap” for using the tool to study consciousness. 

“Transcranial focused ultrasound will let you stimulate different parts of the brain in healthy subjects, in ways you just couldn’t before,” says Daniel Freeman, an MIT researcher and co-author of a new paper on the subject. “This is a tool that’s not just useful for medicine or even basic science, but could also help address the hard problem of consciousness. It can probe where in the brain are the neural circuits that generate a sense of pain, a sense of vision, or even something as complex as  human thought.”

Transcranial focused ultrasound is noninvasive and reaches deeper into the brain, with greater resolution, than other forms of brain stimulation, such as transcranial magnetic or electrical stimulation.

“There are very few reliable ways of manipulating brain activity that are safe but also work,” says Matthias Michel, an MIT philosopher who studies consciousness and co-authored the new work.

The paper, “Transcranial focused ultrasound for identifying the neural substrate of conscious perception,” is published in Neuroscience and Biobehavioral Reviews. The authors are Freeman, a technical staff member at MIT Lincoln Laboratory; Brian Odegaard, an assistant professor of psychology at the University of Florida; Seung-Schik Yoo, an associate professor of radiology at Brigham and Women’s Hospital and Harvard Medical School; and Michel, an associate professor in MIT’s Department of Philosophy and Linguistics. 

Pinpointing causality

Brain research is especially difficult because of the challenge of studying healthy individuals. Apart from neurosurgery, there are very limited ways to gain knowledge of the deepest structures in the human brain. From the outside of the head, noninvasive approaches like MRIs and other kinds of ultrasounds yield some imaging information, while the electroencephalogram (EEG) shows electrical activity in the brain. Conversely, with transcranial focused ultrasound, acoustic waves are transmitted through the skull, focusing down to a target area of a few millimeters, allowing specific brain structures to be stimulated to study the resulting effect. It could therefore be a productive tool for robust experiments.

“It truly is the first time in history that one can modulate activity deep in the brain, centimeters from the scalp, examining subcortical structures with high spatial resolution,” Freeman says. “There’s a lot of interesting emotional circuits that are deep in the brain, but until now you couldn’t manipulate them outside of the operating room.”

Crucially, the technology may help researchers determine cause-and-effect patterns, precisely because its ultrasound waves modulate brain activity. Many studies of consciousness today may measure brain activity in relation to, say, visual stumuli, since visual processing is among the core components of consciousness. But it’s not necessarily clear if the brain activity being measured represents the generation of consciousness, or a mere consequence of consciousness. By manipulating the brain’s activity, researchers can better grasp which actions help constitute consciousness, or are byproducts of it.  

“Transcranial focused ultrasound gives us a solution to that problem,” says Michel.

The “roadmap” laid out in the new paper aims to help distinguish between two main conceptions of consciousness. Broadly, the “cognitivist” conception holds that the neural activity that generates conscious experience must involve higher-level mental processes, such as reasoning or self-reflection. These processes link information from many different parts of the brain into a coherent whole, likely using the frontal cortex of the brain. 

By contrast, the “non-cognitivist” idea of consciousness takes the position that conscious experience does not require such cognitive machinery; instead, specific patterns of neural activity give rise directly to particular subjective experiences, without the need for sophisticated interpretive processes. In this view, brain activity responsible for consciousness may be more localized, at the back of the cortex or in subcortical structures at the back of the brain.

To use transcranial focused ultrasound productively, the researchers lay out a series of more specific questions that experiments might address: What is the role of the prefrontal cortex in conscious perception? Is perception generated locally, or are brain-wide networks required? If consciousness arises across distant regions of the brain, how are perceptions from those areas linked into one unified experience? And what is the role of subcortical structures in conscious activity?

By modulating brain activity in experiments involving, say, visual stimuli, researchers could draw closer to answers about the brain areas that are necessary in the production of conscious thought. The same goes for studies of, for instance, pain, another core sensation linked with consciousness. We pull our hand back from a hot stove before the pain hits us. But how is the conscious sensation of pain generated, and where in the brain does that happen? 

“It’s a basic science question, how is pain generated in the brain,” Freeman says. “And it’s surprising there is such uncertainty … Pain could stem from cortical areas, or it could be deeper brain structures. I’m interested in therapies, but I’m also curious if subcortical structures may play a bigger role than appreciated. It could be the physical manifestation of pain is subcortical. That’s a hypothesis. But now we have a tool to examine it.”

Experiments ahead

Freeman and Michel are not just abstractly charting a course for others to follow; they are planning forthcoming experiments centered on stimulation of the visual cortex, before moving on to higher-level areas in frontal cortex. While methods of recording brain activity, such as an EEG reveal areas that are visually responsive, these new experiments are aiming to build a more complete, causal picture of the entire process of visual perception and its associated brain activity.

“It’s one thing to say if these neurons reponded electrically. It’s another thing to say if a person saw light,” Freeman says.

Michel, for his part, is also playing an active role in generating further interest in studies of consciousness at MIT. Along with Earl Miller, the Picower Professor of Neuroscience in MIT’s Department of Brain and Cognitive Sciences, Michel is a co-founder of the MIT Consciousness Club, a cross-disciplinary effort to spur further academic study of consciousness, on campus and at other Boston-area institutions. 

The MIT Consciousness Club is supported in part by MITHIC, the MIT Human Insight Collaborative, an initiative backed by the School of Humanities, Arts, and Social Sciences. The program aims to hold monthly events, while grappling with the cutting edge of consciousness research.

At the moment, Michel believes, the cutting edge very much involves transcranial focused ultrasound.

“It’s a new tool, so we don’t really know to what extent it’s going to work,” Michel says. “But I feel there’s low risk and high reward. Why wouldn’t you take this path?”

The research for the paper was supported by the U.S. Department of the Air Force. 

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Written by Peter Dizikes, MIT News

Paper: “Transcranial focused ultrasound for identifying the neural substrate of conscious perception”

https://www.sciencedirect.com/science/article/abs/pii/S0149763425004865

 

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Journal

Neuroscience & Biobehavioral Reviews

DOI

10.1016/j.neubiorev.2025.106485 

Article Title

“Transcranial focused ultrasound for identifying the neural substrate of conscious perception”

 

FAU study reveals social, family and health factors behind teen bullying

Florida Atlantic University

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Adolescents who were overweight, struggled to make friends, were born outside the U.S., or faced mental health challenges such as anxiety, depression, ADD/ADHD or learning disabilities were at greater risk of involvement in bullying, either as victims, perpetrators or both.

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Credit: Alex Dolce, Florida Atlantic University

Bullying in the United States remains a serious public health issue with consequences that extend far beyond the school grounds. For adolescents, being bullied – or engaging in bullying – can lead to lasting mental, physical and social challenges that follow them into adulthood. Victims face higher risks of depression, anxiety, hallucinations, suicidality, and other long-term mental health conditions, while perpetrators often experience increased rates of delinquency, dating violence and criminal behavior.

Social factors, including socioeconomic disadvantages, race and physical differences, further intensify the problem. Bullying is not just a childhood rite of passage – it is a critical societal issue with enduring impacts on health, education and community well-being.

Researchers from Florida Atlantic University’s Charles E. Schmidt College of Medicine took a deep dive into the risk factors of bullying among U.S. adolescents ages 12 to 17 using data from the National Survey of Children’s Health, a U.S. Census Bureau household survey collecting information on children’s physical and mental health, access to care, and family and social environments. The study focused on how socioeconomic challenges, social influences, family dynamics, and pre-existing health conditions contribute to the risk of bullying, with the goal of informing more effective prevention strategies.

The results of the study, published in the journal Child Psychiatry & Human Development, found that adolescents who were overweight, struggled to make friends, were born outside the U.S., or faced mental health challenges – such as anxiety, depression, ADD/ADHD – or learning disabilities were at higher risk of being involved in bullying, either as victims, perpetrators or both.

Overweight and obese teens, in particular, faced higher odds of being both bullied and bullying others, and those who engaged in bullying also showed higher rates of behavioral problems, depression, frequent arguments and social difficulties.

Foreign-born adolescents were more likely to be bullied than their U.S.-born peers. While both groups often internalized their problems, parental monitoring appeared to help protect foreign-born teens, possibly because they relied more on family support when facing social challenges.

Among all 37,425 adolescents surveyed between 2022 and 2023, 13,724 (36.7%) reported being bullied in the past year, with 24.7% experiencing bullying once or twice, 6.4% monthly, 3.4% weekly, and 2.1% nearly every day. Additionally, 4,936 (13.2%) adolescents reported bullying others, with 10.4% doing so once or twice, and smaller percentages engaging in bullying more frequently.

The findings point to a cycle in which being bullied can increase the likelihood of bullying others. Many of the same factors were linked to both experiences, underscoring the complex and interconnected nature of teen bullying.

“Our findings underscore the urgent need for evidence-based interventions to address bullying and its impact on adolescents’ mental, physical and social well-being,” said Lea Sacca, Ph.D., senior author and an assistant professor of population health in the Schmidt College of Medicine. “Effective strategies involve shaping student attitudes, training school staff to respond to bullying, and engaging caregivers. Schools that implement these approaches have seen meaningful reductions in bullying and improvements in student mental health, offering lasting support to those most at risk.”

Few school-based bullying prevention programs actively involve parents, even though programs that engage caregivers tend to see greater reductions in both bullying victimization and perpetration. To overcome these gaps, the researchers say that prevention strategies should also be culturally sensitive and accessible – offering workshops at flexible times, providing translated materials and arranging childcare during events.

Successful programs rely on collaboration between parents and teachers, incorporating parental feedback on interventions and addressing concerns about their children’s behavior. Parents are also encouraged to strengthen relationships with their children and model positive social interactions and conflict resolution at home.

School policies play an important role as well. While there are no federal antibullying laws, the U.S. Department of Education has recommended 16 components for state laws, including clear definitions of bullying, characteristics of common targets, and detailed guidance for school districts. Although all states have some form of antibullying laws, only a few fully adopt the DOE’s recommendations, highlighting the need for stronger, more consistent policies.

“Preventing bullying requires a team effort – schools, parents and communities working together,” said Sacca. “When parents are actively involved and school policies are strong and consistent, we can create safer environments that support every student’s mental, physical and social well-being.”

Study co-authors are FAU medical students Pedro Soto; Victoria Reis; Isabella Abraham; Cheila Llorens; Ayden Dunn; and Austin Lent.

- FAU -

About the Charles E. Schmidt College of Medicine:

Florida Atlantic University’s Charles E. Schmidt College of Medicine is one of approximately 159 accredited medical schools in the U.S. The college was launched in 2010, when the Florida Board of Governors made a landmark decision authorizing FAU to award the M.D. degree. After receiving approval from the Florida legislature and the governor, it became the 134th allopathic medical school in North America. With more than 170 full and part-time faculty and more than 1,400 affiliate faculty, the college matriculates 80 medical students each year and has been nationally recognized for its innovative curriculum. The college offers M.S. (thesis and non-thesis) and Ph.D. programs in biomedical science, along with a certificate in genomics and precision medicine. Taught by top researchers, the curriculum combines innovative coursework with hands-on learning, preparing graduates for careers in medicine, research, industry, and academia. To further Florida Atlantic’s commitment to increase much needed medical residency positions in Palm Beach County and to ensure that the region will continue to have an adequate and well-trained physician workforce, the FAU Charles E. Schmidt College of Medicine Consortium for Graduate Medical Education (GME) was formed in fall 2011 with five leading hospitals in Palm Beach County. The consortium currently has five Accreditation Council for Graduate Medical Education (ACGME) accredited residencies including internal medicine, surgery, emergency medicine, psychiatry, and neurology, and five fellowships in cardiology, hospice and palliative care, geriatrics, vascular surgery, and pulmonary disease and critical care medicine. The college also manages the Florida Atlantic University Medical Group, offering comprehensive primary care, and the Marcus Institute of Integrative Health specializes in integrative pain management, precision therapies, and mental health.

 

About Florida Atlantic University:

Florida Atlantic University serves more than 32,000 undergraduate and graduate students across six campuses along Florida’s Southeast coast. Recognized as one of only 21 institutions nationwide with dual designations from the Carnegie Classification - “R1: Very High Research Spending and Doctorate Production” and “Opportunity College and University” - FAU stands at the intersection of academic excellence and social mobility. Ranked among the Top 100 Public Universities by U.S. News & World Report, FAU is also nationally recognized as a Top 25 Best-In-Class College and cited by Washington Monthly as “one of the country’s most effective engines of upward mobility.” As a university of first choice for students across Florida and the nation, FAU welcomed its most academically competitive incoming class in university history in Fall 2025. To learn more, visit www.fau.edu.

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Journal

Child Psychiatry & Human Development

DOI

10.1007/s10578-025-01936-x 

Method of Research

Meta-analysis

Subject of Research

People

Article Title

Risk Factors for Bullying in US Adolescents Aged 12–17