It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Friday, June 02, 2023
That’s not nuts: Almond milk yogurt packs an overall greater nutritional punch than dairy-based
UMass Amherst food science major completes comparison of 612 plant-based and dairy yogurts
AMHERST, Mass. – In a nutritional comparison of plant-based and dairy yogurts, almond milk yogurt came out on top, according to research led by a University of Massachusetts Amherst food science major.
“Plant-based yogurts overall have less total sugar, less sodium and more fiber than dairy, but they have less protein, calcium and potassium than dairy yogurt,” says lead author Astrid D’Andrea, a graduating senior whose paper was published May 25 in a special issue of the journal Frontiers in Nutrition titled Food of the Future: Meat and Dairy Alternatives. “But when looking at the overall nutrient density, comparing dairy yogurt to plant-based yogurt, with the nutrients that we looked at, almond yogurt has a significantly higher nutrient density than dairy yogurt and all other plant-based yogurts.”
Working in the lab of senior author Alissa Nolden, a sensory scientist and assistant professor of food science, D’Andrea was interested in comparing the nutritional values of plant-based and dairy yogurts, an area of research she found lacking. Driven by concerns over environmental sustainability and eating less animal-based food products, the plant-based yogurt market is expected to explode from $1.6 billion in 2021 to $6.5 billion in 2030.
“Plant-based diets are gaining popularity, especially in American culture, but just because it’s plant-based doesn’t mean it’s more nutritious,” says D’Andrea, of Hazlet, N.J., who is heading to graduate school in food science at Penn State. “There has to be specific research that answers that question.”
D’Andrea collected nutritional information for 612 yogurts, launched between 2016 and 2021, using the Mintel Global New Products Database, accessed through UMass Libraries. She used the Nutrient Rich Foods (NRF) Index, which assigns scores based on the nutrient density of foods. “This allowed us to compare the nutritional density of the yogurts based on nutrients to encourage (protein, fiber, calcium, iron, potassium, vitamin D) and nutrients to limit (saturated fat, total sugar, sodium),” D’Andrea writes in her paper.
The researchers chose the NRF model based on the nutritional benefits of dairy yogurt, which provides a complete protein, something plant-based products are unable to do.
Of the 612 yogurts analyzed, 159 were full-fat dairy, 303 were low- and nonfat dairy, 61 were coconut, 44 were almond, 30 were cashew and 15 were oat. The researchers used the NRF Index to rank the yogurts from the highest to lowest nutrient density: almond, oat, low- and nonfat dairy, full-fat dairy, cashew and coconut.
D’Andrea attributed the high scores of almond and oat yogurts to their low levels of total sugar, sodium and saturated fat. She and Nolden say the study’s findings can inform the food industry on ways to improve the formulation and nutritional composition of plant-based yogurts.
One option the researchers offer is creating a hybrid yogurt that is both plant- and dairy-based. This will add protein, vitamin B12 and calcium while still minimizing total sugar, sodium and saturated fat.
“Going from dairy all the way to plant-based is a big change,” Nolden says. “There are changes in the nutritional profile, and there’s change in the sensory profile, which might prevent consumers from trying it.”
In fact, a recent study conducted in the Nolden lab led by former UMass Amherst visiting researcher Maija Greis investigated consumer acceptance of blended plant-based and dairy yogurt and found that people preferred the blended yogurt over the plant-based one.
“Blending provides advantages,” Nolden says. “It provides a complete protein, and the dairy part helps to form the gelling structure within the yogurt that so far we are unable to replicate in a plant-based system.”
The UMass Amherst team says further research is warranted, based on their findings that suggest a way to maximize the nutrition and functional characteristics of yogurt.
“If we can blend plant-based and dairy yogurt, we can achieve a desirable sensory profile, a potentially better nutritional profile and have a smaller impact on the environment,” Nolden says.
IMAGE: SENIOR CHEMIST DI-JIA LIU INSPECTS CATALYST SAMPLE INSIDE TUBE FURNACE AFTER HEAT TREATMENT WHILE POSTDOC CHENZHAO LI CARRIES A PRESSURE REACTOR FOR CATALYST SYNTHESIS.view more
CREDIT: (IMAGE BY ARGONNE NATIONAL LABORATORY.)
A plentiful supply of clean energy is lurking in plain sight. It is the hydrogen we can extract from water (H2O) using renewable energy. Scientists are seeking low-cost methods for producing clean hydrogen from water to replace fossil fuels, as part of the quest to combat climate change.
Hydrogen can power vehicles while emitting nothing but water. Hydrogen is also an important chemical for many industrial processes, most notably in steel making and ammonia production. Using cleaner hydrogen is highly desirable in those industries.
“By using the cobalt-based catalyst prepared by our method, one could remove the main bottleneck of cost to producing clean hydrogen in an electrolyzer.” — Di-Jia Liu, senior chemist at Argonne
A multi-institutional team led by the U.S. Department of Energy’s (DOE) Argonne National Laboratory has developed a low-cost catalyst for a process that yields clean hydrogen from water. Other contributors include DOE’s Sandia National Laboratories and Lawrence Berkeley National Laboratory, as well as Giner Inc.
“A process called electrolysis produces hydrogen and oxygen from water and has been around for more than a century,” said Di-Jia Liu, senior chemist at Argonne. He also holds a joint appointment in the Pritzker School of Molecular Engineering at the University of Chicago.
Proton exchange membrane (PEM) electrolyzers represent a new generation of technology for this process. They can split water into hydrogen and oxygen with higher efficiency at near room temperature. The reduced energy demand makes them an ideal choice for producing clean hydrogen by using renewable but intermittent sources, such as solar and wind.
This electrolyzer runs with separate catalysts for each of its electrodes (cathode and anode). The cathode catalyst yields hydrogen, while the anode catalyst forms oxygen. A problem is that the anode catalyst uses iridium, which has a current market price of around $5,000 per ounce. The lack of supply and high cost of iridium pose a major barrier for widespread adoption of PEM electrolyzers.
The main ingredient in the new catalyst is cobalt, which is substantially cheaper than iridium. “We sought to develop a low-cost anode catalyst in a PEM electrolyzer that generates hydrogen at high throughput while consuming minimal energy,” Liu said. “By using the cobalt-based catalyst prepared by our method, one could remove the main bottleneck of cost to producing clean hydrogen in an electrolyzer.”
Giner Inc., a leading research and development company working toward commercialization of electrolyzers and fuel cells, evaluated the new catalyst using its PEM electrolyzer test stations under industrial operating conditions. The performance and durability far exceeded that of competitors’ catalysts.
Important to further advancing the catalyst performance is understanding the reaction mechanism at the atomic scale under electrolyzer operating conditions. The team deciphered critical structural changes that occur in the catalyst under operating conditions by using X-ray analyses at the Advanced Photon Source (APS) at Argonne. They also identified key catalyst features using electron microscopy at Sandia Labs and at Argonne’s Center for Nanoscale Materials (CNM). The APS and CNM are both DOE Office of Science user facilities.
“We imaged the atomic structure on the surface of the new catalyst at various stages of preparation,” said Jianguo Wen, an Argonne materials scientist.
In addition, computational modeling at Berkeley Lab revealed important insights into the catalyst’s durability under reaction conditions.
The team’s achievement is a step forward in DOE’s Hydrogen Energy Earthshot initiative, which mimics the U.S. space program’s “Moon Shot” of the 1960s. Its ambitious goal is to lower the cost for green hydrogen production to one dollar per kilogram in a decade. Production of green hydrogen at that cost could reshape the nation’s economy. Applications include the electric grid, manufacturing, transportation and residential and commercial heating.
“More generally, our results establish a promising path forward in replacing catalysts made from expensive precious metals with elements that are much less expensive and more abundant,” Liu noted.
In addition to Liu, Argonne authors are Lina Chong (now at Shanghai Jiao Tong University), Jianguo Wen, Haiping Xu, A. Jeremy Kropf, Wenqian Xu and Xiao-Min Lin. Authors from Berkeley Lab include Guoping Gao, Haixia Li and Ling-Wang Wang. The author from Sandia Labs is Joshua D. Sugar. Contributors Zach Green and Hui Xu are from Giner Inc.
About Argonne’s Center for Nanoscale Materials The Center for Nanoscale Materials is one of the five DOE Nanoscale Science Research Centers, premier national user facilities for interdisciplinary research at the nanoscale supported by the DOE Office of Science. Together the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative. The NSRCs are located at DOE’s Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge, Sandia and Los Alamos National Laboratories. For more information about the DOE NSRCs, please visit https://science.osti.gov/User-Facilities/User-Facilities-at-a-Glance.
About the Advanced Photon Source
The U. S. Department of Energy Office of Science’s Advanced Photon Source (APS) at Argonne National Laboratory is one of the world’s most productive X-ray light source facilities. The APS provides high-brightness X-ray beams to a diverse community of researchers in materials science, chemistry, condensed matter physics, the life and environmental sciences, and applied research. These X-rays are ideally suited for explorations of materials and biological structures; elemental distribution; chemical, magnetic, electronic states; and a wide range of technologically important engineering systems from batteries to fuel injector sprays, all of which are the foundations of our nation’s economic, technological, and physical well-being. Each year, more than 5,000 researchers use the APS to produce over 2,000 publications detailing impactful discoveries, and solve more vital biological protein structures than users of any other X-ray light source research facility. APS scientists and engineers innovate technology that is at the heart of advancing accelerator and light-source operations. This includes the insertion devices that produce extreme-brightness X-rays prized by researchers, lenses that focus the X-rays down to a few nanometers, instrumentation that maximizes the way the X-rays interact with samples being studied, and software that gathers and manages the massive quantity of data resulting from discovery research at the APS.
This research used resources of the Advanced Photon Source, a U.S. DOE Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.
Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science.
The U.S. Department of Energy’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit https://energy.gov/science.
Apr 14, 2022 ... Some conspiracy theories just refuse to die, and right now a viral TikTok is reviving a true classic: The idea of a secret invention that ...
First let me unveil the secret "engine that ran on water": This engine was ... to break down water to hydrogen and oxygen then fuel the car with hydrogen.
Cars that will run on hydrogen fuel produce only water, not exhaust fumes… ... as the fuel of the future dates back to Jules Verne, and by the 1930s was a ...
Monkey see, monkey do: observing macaques to better understand movement synchronization
Researchers from the National Institute for Physiological Sciences find that macaques synchronize their movements with those of others, with implications for understanding why primates synchronize movements in the first place
IMAGE: WHEN TWO MONKEYS FACING EACH OTHER MAKE REPETITIVE ARM MOVEMENTS AT THEIR OWN PACES, THEIR MOVEMENTS SPONTANEOUSLY BECOME SYNCHRONIZED.view more
CREDIT: SAEKA TOMATSU
Okazaki, Japan – Humans have long known how to synchronize to rhythms. But now, researchers from Japan have found that movement synchronization spontaneously takes place in macaque monkeys as well. In a study recently published in Proceedings of the National Academy of Sciences (PNAS), a research team led by the National Institute for Physiological Sciences has observed ‘social motor entrainment’, i.e., movement synchronization between individuals, in macaques in a laboratory environment. Although social motor entrainment has been suggested to reinforce social cohesion, the neural underpinnings of this mechanism are not well understood, which the researchers aimed to address. “Social motor entrainment is robust in humans,” says lead author of the study Saeka Tomatsu. “Because synchronized movements encourage social cohesion in humans, they may play an important role in the formation of large social networks among groups.” To investigate the evolutionary origin of social motor entrainment, the researchers examined the way in which macaques synchronized their movements with those of other macaques. They compared synchronization across several types of situations: movements between a pair of real monkeys, the movements of a monkey watching a video of a monkey making the same repetitive movements, and the movements of a monkey watching a video of a horizontal bar sliding in the same direction as the real-life movements. “The results were surprising,” explains Masaki Isoda, senior author. “We found that the macaques exhibited social motor entrainment without prompting by the experimenters.” Furthermore, the observed motor entrainment varied according to the animal pairs, social hierarchy, and the type of stimulus. “The motor entrainment in macaques was facilitated by real-time social exchanges, and was diminished when using videos of macaques making the same movements,” explains lead author Saeka Tomatsu. “Therefore, this type of motor entrainment appears to be specific to real-life social interactions.” Creating research settings and tasks that can be used to ethically study behavior is valuable; the framework created and tested in this study could facilitate research about the neurological and evolutionary origins of social behavior in non-human primates. This achievement, together with the verification of the presence of motor entrainment during real-time social exchanges, sets the stage for future research on motor synchrony as a social phenomenon. This could lead to new understanding about human conditions connected to impaired social cohesion, such as autism spectrum disorder.
MARSHALL UNIVERSITY JOAN C. EDWARDS SCHOOL OF MEDICINE
HUNTINGTON, W.Va. – A Marshall University study found that a virtual sex education tool improved reproductive health knowledge scores and measures of self-efficacy among adolescent girls.
The findings, published last month in Sex Education, a leading international journal on sex, sexuality and relationships in education, found that sexual health knowledge scores on a validated scale increased among participants, along with improved measures of self-efficacy regarding birth control, healthy relationships and sexually transmitted infection (STI) prevention. Notably, a greater proportion of participants reported improved confidence in obtaining birth control, recognizing an unhealthy relationship and testing for STIs.
A research team at the Marshall University Joan C. Edwards School of Medicine conducted a baseline assessment of sexual health knowledge among adolescent females ages 14 to 18. Participants also answered questions about past experiences with school sex education programs and self-efficacy. They then completed the online curriculum available at www.marshallteentalk.org, which covers a range of sexual health topics presented through short, animated videos. A post-survey then reassessed participants’ sexual health knowledge, along with the same measures of self-efficacy.
“Adolescents use websites and social media for sexual health information; therefore, there is a great need for accurate, evidence-based online reproductive health tools,” said Marshall Health Pediatric and Adolescent Gynecologist Jennie L. Yoost, M.D., M.Sc., an associate professor at the Joan C. Edwards School of Medicine and senior author of the study. “Marshall Teen Talk was designed specifically to provide local adolescents an accessible and accurate resource for reproductive health that they can trust. This study validates the website as an effective teaching tool.”
In the current study, 30.3% of participants reported they had never had sex education classes in school. The online curriculum was overwhelmingly favored by study participants, with 94% reporting the information was presented in a way that was easy to understand, and 93.9% reported they would recommend the website to a friend.
In addition to Yoost, the research team included Dani Roth; Emma Nellhaus, M.D.; Morgan Ruley; Ariana Hess, M.D.; and Rajan Lamichhane, Ph.D. The team will expand future studies to include male and nonbinary adolescents, as well as partnerships with teachers. As adolescents in rural areas are less likely to seek out sexual health services, this website can also potentially serve our community by linking individuals to specific health resources and clinical needs.
Marshall Teen Talk was established in 2014 by Yoost as an after-school telehealth outreach to rural West Virginia high schools. Since that time, the program evolved into an evidence-based online curriculum available at www.marshallteentalk.org that can be completed in approximately 45 minutes and can be used as a supplement to classroom learning. The project was funded through rural health initiative grants from the Robert C. Byrd Center for Rural Health at Marshall University with funding from the West Virginia Higher Education Policy Commission and private donors. Website design and animation were developed by Bulldog Creative Services.
To view the article in its entirety, visit “A virtual sex education tool improved reproductive health knowledge among adolescent girls” by Roth et al., please visit https://doi.org/10.1080/14681811.2023.2203909.
A virtual sex education tool improved reproductive health knowledge among adolescent girls
No-till revolution could stop Midwest topsoil loss in its tracks
If Midwestern farms all adopted low-intensity tilling practices or stopped tilling entirely, the erosion of critical topsoil could decrease by 95% in the next 100 years, new study finds
No-till revolution could stop Midwest topsoil loss in its tracks
If Midwestern farms all adopted low-intensity tilling practices or stopped tilling entirely, the erosion of critical topsoil could decrease by 95% in the next 100 years, new study finds
Contact information for the researchers: Jeffrey Kwang, University of Minnesota, kwang004@umn.edu (UTC-5 hours)
By the numbers:
At current use rates, conventional tilling would result in the loss of nearly 10 billion tons (nearly 9 billion metric tons) of topsoil in the next century
If the U.S. Midwest sees 100% adoption of sustainable tilling, erosion from tilling would nearly halt within a century
WASHINGTON — Intense agricultural activity beginning in the mid-1800s has eroded the U.S. Midwest’s topsoil, the rich upper layer of soil that crops need to grow. That erosion causes nearly $3 billion in annual losses from lower crop productivity, previous work has found. But if more farmers adopt more sustainable “no-till” or “low-till” practices, costly erosion could be essentially halted, a new study finds.
The study is published in AGU’s journal Earth’s Future, which publishes interdisciplinary research on the past, present and future of our planet and its inhabitants.
Erosion and soil movement occur on farms when water runs across the land, wind removes fine dirt, and plows churn up and loosen the soil. The “churning” process is called tilling. Farmers till soil to loosen soil, mix in nutrients and help suppress weed growth. But tilling can also expose more soil to wind and water, increasing erosion.
Co-authors of the new study previously found the erosion rate since the 1800s was about 2 millimeters per year (0.08 inches), or two orders of magnitude faster than rates in pre-settler prairies. Across the Midwestern study area, about 40% of farms are using less intensive, more sustainable alternatives to plow-based tilling. But erosion is still a big problem.
“Two millimeters per year is a lot,” said Jeffrey Kwang, a landscape modeler at the University of Minnesota who led the study. “It sounds slow, but for landscape processes, that is very fast.” The new model used in this study predicts that soil erosion is currently occurring at about 1 millimeter (0.04 inches) per year, Kwang said, “which is still a high rate.”
The new study builds on previous work that focused on the past and present by exploring the future fate of soils in the Midwest. Kwang simulated the next century of farming in the Midwest under conventional and more sustainable tilling scenarios and predicts how topsoil erosion and carbon loss would respond. His modeling focused on physical soil movement from plowing and tilling and did not incorporate hydrologic models, as previous research on agricultural erosion has largely focused on water rather than plowing practices.
Under conventional tilling at the rates used today, over the next century, the Midwest would lose about 9.7 billion tons (about 8.8 billion metric tons) of soil, the researchers found, likely causing billions of dollars of losses. It would also result in about a 4% loss of surface soil organic carbon, which would further decrease crop productivity. Switching to fully no-till or to low-till practices, such as strip tilling and drill planting, would keep this from happening.
Kwang uncovered a twist: Over the next few hundred years, the rate of soil erosion might actually slow down. That’s because as a hill erodes, it essentially gets flatter and erodes more slowly. But that doesn’t necessarily buy time, he said.
“The best time to do something about erosion is now,” Kwang said. “The fastest erosion rates we’re going to see are today. If we wait to change up tilling practices, we won’t get as much bang for your buck.” If we wait until the hills are flattened, a significant amount of soil will have been lost and the switch to no-till wouldn’t save as much soil, he added.
Money is a concern because cost is one reason more farmers haven’t adopted low-intensity tilling practices, even though they might be interested in farming more sustainably. Doing so requires a new suite of expensive farming tools, as well as time spent optimizing a new procedure. Geology plays a role, too: Northern farms tend to have dense, fine-grained soils that are more likely to need a plow, thanks to the glaciers that bulldozed the landscape during the last Ice Age.
Ample damage has already been done, Kwang said. “We’ll still have issues with crop productivity because the soils are still gone. So even if we stop erosion, sort of freezing the soils in time, we’d still need to use tactics like regenerative agriculture to try to build back that topsoil.”
Still, Kwang is optimistic. “Erosion is happening now, and we can do something about it,” he said.
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“The Future of Soils in the Midwestern United States”
Authors:
Jeffrey Kwang (corresponding author), Department of Earth, Geographic, and Climate Sciences, University of Massachusetts, Amherst, MA, USA; now at Saint Anthony Falls Laboratory, University of Minnesota, Minneapolis, MN, USA
Evan Thaler, Department of Earth, Geographic, and Climate Sciences, University of Massachusetts, Amherst, MA, USA; now at Earth and Environmental Sciences Division, Los Alamos National Laboratory, Ls Alamos, NM, USA
Isaac Larsen, Department of Earth, Geographic, and Climate Sciences, University of Massachusetts, Amherst, MA, USA
Charles Sherwood Noble (1873 – July 5, 1957) invented a minimum disturbance cultivator called the Noble blade. The Noble blade (or Noble plow) cuts weed ...
Lung infection may be less transmissible than thought
Study calls into question pathogen’s ability to spread from person to person
A little-known bacterium — a distant cousin of the microbes that cause tuberculosis and leprosy — is emerging as a public health threat capable of causing severe lung infections among vulnerable populations, those with compromised immunity or reduced lung function.
Recent research found that various strains of the bacterium, Mycobacterium abscessus, were genetically similar, stoking fears that it was spreading from person to person.
But a new study by Harvard Medical School researchers published May 22 in PNAS,calls those findings into question, offering an alternative explanation behind the genetic similarity of clinical clusters. This suggests that the pathogen may not be that prone to person-to-person transmission after all.
“Our findings make a strong case for a different explanation behind the observed genetic similarities across strains,” said study senior author Maha Farhat, the Gilbert S. Omenn Associate Professor of Biomedical Informatics at HMS and a pulmonary disease expert at Massachusetts General Hospital. Farhat conducted the work in collaboration with Eric Rubin’s lab at the Harvard T.H. Chan School of Public Health.
The results, Farhat added, argue against direct person-to-person transmission in clinical settings and instead point to M. abscessus infections being acquired from the home or other environmental exposures.
In addition to having implications for the precautions that hospitals take to prevent outbreaks, it’s an important new clue into the behavior of a relatively unknown pathogen that poses serious risks for vulnerable populations.
The research not only contributes to the understanding of M. abscessus transmission, but also suggests scientists should be cautious about assuming human transmission when they see genetic similarities in pathogens more generally, said study first author Nicoletta Commins, who conducted the research as a doctoral candidate at HMS and is now a postdoctoral fellow at the Broad Institute.
“Our results certainly do not refute the possibility of person-to-person transmission of Mycobacterium abscessus in some cases, and more research is needed to inform best clinical practice for vulnerable patients,” she said. “However, our work supports a model in which person-to-person transmission may not be as common as it is sometimes suggested to be.”
M. abscessus is a hardy microbe highly resistant to antibiotics and can infect the lungs of immunocompromised people. While it doesn’t pose a threat to most healthy individuals, it can cause severe infection in those with suppressed immunity or people with compromised lung function such as patients with cystic fibrosis, a genetic condition marked by recurrent lung infections and lung scarring. Notably, patients with CF who become infected with this organism become ineligible for lifesaving lung transplants.
The earlier study that sounded the alarm about person-to-person transmission was based on genetic sequencing of M. abscessus samples obtained from cystic fibrosis patients at clinics in the United States, Australia, and Europe, including the United Kingdom. Researchers found few genetic mutations across the samples — a possible sign that the pathogen was spreading directly between humans.
For many pathogens such as TB, for example, recent person-to-person transmission leads to only a few or no mutations between any pair of samples simply because the pathogen does not have much time to acquire genetic mutations, Farhat explained.
“Understandably, observing the genetic similarity between M. abscessus samples caused a great deal of anxiety and fear around how these organisms could be transmitting,” she said.
Clinicians, especially in clinics that treat cystic fibrosis patients, began taking extra precautions to avert transmission. However, follow-up investigations failed to find supporting evidence that human-to-human transmission was happening, raising questions about other possible explanations for the genetic similarities across samples.
Farhat’s team set out to investigate a hypothesis that the samples appeared genetically similar because the pathogen was evolving at a very slow rate.
“We thought, yeah, you observed a small number of mutations, but we don’t know how quickly these mutations are acquired, she explained. “It may be slower than we think, and links between samples that appear recent may not be.’”
The scientists first used a large dataset of M. abscessus genomes to create a “tree of life,” a kind of genetic family tree for the bacterium.
They looked at branches of the tree with clusters of genetically similar strains, then tried to calculate their evolutionary rate. They found that these genetically similar clusters were evolving around 10 times more slowly than typical M. abscessus strains.
Next, they used computer modeling to determine whether the genetic similarities could be explained by the relatively small population size of these bacteria. But even when they simulated extreme population sizes, the result didn’t change. This was an indicator that the high genetic similarity is best explained by a slower evolutionary rate.
Finally, researchers conducted experiments to see how fast different strains of M. abscessus evolved to develop resistance when exposed to antibiotics in the lab. They found that the genetically similar strains evolved much more slowly than other strains.
“These are three separate lines of evidence supporting this idea that these clustered isolates of Mycobacterium abscessus are evolving at a slower rate,” Farhat said.
In addition to reducing concern about person-to-person transmission, the findings provide new insight into a poorly understood pathogen.
In particular, the results offer clues about how a bug found primarily in the environment adapts and changes after it enters the human body — information that could help scientists eventually understand how to prevent and treat infections.
Farhat is now planning follow-up studies that would compare bacteria in the environment with samples taken from patients, to better understand why certain patients become infected.
Authorship, funding, disclosures
Additional authors included Mark R. Sullivan, Kerry McGowen
Evan Koch, and Eric Rubin. The work was partly supported by the Damon Runyon Cancer Research Foundation, DRG-2415-20, with additional support from the Orchestra High Performance Compute Cluster at Harvard Medical School, funded by the NIH NCRR 1S10RR028832-01.
