Study links omega-3s to improved brain structure, cognition at midlife

Holy mackerel! Could eating salmon, cod, tuna, herring or sardines keep our brains healthy and our thinking agile in middle age? New research makes this connection.

Peer-Reviewed Publication

UNIVERSITY OF TEXAS HEALTH SCIENCE CENTER AT SAN ANTONIO

SAN ANTONIO (Oct. 5, 2022) — Eating cold-water fish and other sources of omega-3 fatty acids may preserve brain health and enhance cognition in middle age, new evidence indicates.

Having at least some omega-3s in red blood cells was associated with better brain structure and cognitive function among healthy study volunteers in their 40s and 50s, according to research published online Oct. 5 in Neurology®, the medical journal of the American Academy of Neurology. Faculty of The University of Texas Health Science Center at San Antonio (UT Health San Antonio) and other investigators of the Framingham Heart Study conducted the analysis.

“Studies have looked at this association in older populations. The new contribution here is that, even at younger ages, if you have a diet that includes some omega-3 fatty acids, you are already protecting your brain for most of the indicators of brain aging that we see at middle age,” said Claudia Satizabal, PhD, assistant professor of population health sciences with the Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases at UT Health San Antonio. Satizabal is the lead author of the study.

Volunteers’ average age was 46. The team looked at the relation of red blood cell omega-3 fatty acid concentrations with MRI and cognitive markers of brain aging. Researchers also studied the effect of omega-3 red blood cell concentrations in volunteers who carried APOE4, a genetic variation linked to higher risk of Alzheimer’s disease.

The study of 2,183 dementia- and stroke-free participants found that:

• Higher omega-3 index was associated with larger hippocampal volumes. The hippocampus, a structure in the brain, plays a major role in learning and memory.
• Consuming more omega-3s was associated with better abstract reasoning, or the ability to understand complex concepts using logical thinking.
• APOE4 carriers with a higher omega-3 index had less small-vessel disease. The APOE4 gene is associated with cardiovascular disease and vascular dementia.

Researchers used a technique called gas chromatography to measure docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) concentrations from red blood cells. The omega-3 index was calculated as DHA plus EPA.

“Omega-3 fatty acids such as EPA and DHA are key micronutrients that enhance and protect the brain,” said study coauthor Debora Melo van Lent, PhD, postdoctoral research fellow at the Biggs Institute. “Our study is one of the first to observe this effect in a younger population. More studies in this age group are needed.”

The team divided participants into those who had very little omega-3 red blood cell concentration and those who had at least a little and more. “We saw the worst outcomes in the people who had the lowest consumption of omega-3s,” Satizabal said. “So, that is something interesting. Although the more omega-3 the more benefits for the brain, you just need to eat some to see benefits.”

Researchers don’t know how DHA and EPA protect the brain. One theory is that, because those fatty acids are needed in the membrane of neurons, when they are replaced with other types of fatty acids, that’s when neurons (nerve cells) become unstable. Another explanation may have to deal with the anti-inflammatory properties of DHA and EPA. “It’s complex. We don’t understand everything yet, but we show that, somehow, if you increase your consumption of omega-3s even by a little bit, you are protecting your brain,” Satizabal said.

It's encouraging that DHA and EPA also protected APOE4 carriers’ brain health. “It’s genetics, so you can’t change it,” Melo van Lent said, referring to the vulnerability of this risk group. “So, if there is a modifiable risk factor that can outweigh genetic predisposition, that’s a big gain.”

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Association of Red Blood Cell Omega-3 Fatty Acids with MRI Markers and Cognitive Function in Midlife – The Framingham Heart Study

Claudia L. Satizabal, PhD; Jayandra J. Himali, PhD; Alexa S. Beiser, PhD; Vasan S. Ramachandran, MD; Debora Melo van Lent, PhD; Dibya Himali, MS; Hugo J. Aparicio, MD, MPH; Pauline Maillard, PhD; Charles DeCarli, MD; William S. Harris, PhD; and Sudha Seshadri, MD.

 First published: Oct. 5, 2022, Neurology

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The University of Texas Health Science Center at San Antonio (UT Health San Antonio), a primary driver for San Antonio’s $42.4 billion health care and biosciences sector, is the largest research university in South Texas with an annual research portfolio of $350 million. Driving substantial economic impact with its five professional schools, a diverse workforce of more than 7,000, an annual operating budget of more than $1 billion and a clinical practice that provides more than 2 million patient visits each year, UT Health San Antonio plans to add more than 1,500 higher-wage jobs over the next five years to serve San Antonio, Bexar County and South Texas. To learn about the many ways “We make lives better®,” visit http://uthscsa.edu.

Stay connected with The University of Texas Health Science Center at San Antonio on Facebook, Twitter, LinkedIn, Instagram and YouTube.

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The Glenn Biggs Institute for Alzheimer’s and Neurodegenerative Diseases is dedicated to providing comprehensive dementia care while advancing treatment through clinical trials and research. The Biggs Institute is a National Institute on Aging (NIA)-designated Alzheimer’s Disease Research Center (ADRC). In addition to patient care and research, the Biggs Institute partners with the School of Nursing at UT Health San Antonio to offer the Caring for the Caregiver program.

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JOURNAL

Neurology

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Study links omega-3s to improved brain structure, cognition at midlife

ARTICLE PUBLICATION DATE

5-Oct-2022

Can eating omega-3 fatty acids in midlife help your brain?

Peer-Reviewed Publication

AMERICAN ACADEMY OF NEUROLOGY

MINNEAPOLIS – An exploratory study suggests that people who eat more foods with omega-3 fatty acids in midlife may have better thinking skills and even better brain structure than people who eat few foods with the fatty acids. The study is published in the October 5, 2022, online issue of Neurology®, the medical journal of the American Academy of Neurology. Omega-3 fatty acids are found in fish such as salmon, sardines, lake trout and albacore tuna. They are also found in foods fortified with the fatty acids or supplements.

“Improving our diet is one way to promote our brain health,” said study author Claudia L. Satizabal, PhD, of the University of Texas Health Science Center at San Antonio. “If people could improve their cognitive resilience and potentially ward off dementia with some simple changes to their diet, that could have a large impact on public health. Even better, our study suggests that even modest consumption of omega-3 may be enough to preserve brain function. This is in line with the current American Heart Association dietary guidelines to consume at least two servings of fish per week to improve cardiovascular health.”

The cross-sectional study involved 2,183 people with an average age of 46 who did not have dementia or stroke. Their levels of omega-3 fatty acids were measured. They took tests of their thinking skills. They had scans to measure brain volumes.

The people in the low group had an average of 3.4% of their total fatty acids as omega-3 fatty acids compared to an average of 5.2% for people in the high group. An optimal level is 8% or higher. Levels between 4% and 8% are considered intermediate. Levels below 4% are considered low.

Researchers adjusted for factors that could affect results. They also applied a mathematical process to normalize the data. They observed that people who ate higher levels of omega-3 fatty acids not only had higher average scores on a test of abstract reasoning, they also had larger average volumes in the hippocampus area of their brains, which plays an important role in memory.

“These results need to be confirmed with additional research, but it’s exciting that omega-3 levels could play a role in improving cognitive resilience, even in middle-aged people,” Satizabal said.

She noted that the study was a snapshot in time, and participants were not followed over time, so the results do not prove that eating omega-3 fatty acids will preserve brain function. It only shows an association.  

While the study included a small proportion of people of many races/ethnicities, Satizabal said that the majority of the sample were non-Hispanic white adults, which may limit the ability to apply the results to other groups.

The study was supported by the National Heart, Lung, and Blood Institute, National Institute on Aging and National Institute of Neurological Disorders and Stroke.

Learn more about brain health at BrainandLife.org, home of the American Academy of Neurology’s free patient and caregiver magazine focused on the intersection of neurologic disease and brain health. Follow Brain & Life® on Facebook, Twitter and Instagram.

When posting to social media channels about this research, we encourage you to use the hashtags #Neurology and #AANscience.

The American Academy of Neurology is the world’s largest association of neurologists and neuroscience professionals, with over 38,000 members. The AAN is dedicated to promoting the highest quality patient-centered neurologic care. A neurologist is a doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system such as Alzheimer’s disease, stroke, migraine, multiple sclerosis, concussion, Parkinson’s disease and epilepsy.

For more information about the American Academy of Neurology, visit AAN.com or find us on Facebook, Twitter, Instagram, LinkedIn and YouTube.

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JOURNAL

Neurology

Being absent while awake: how mind blanking helps us understand ongoing thinking

Study conducted by ULiège GIGA CRC In vivo Imanging researchers shows that "Mind blanking" (MB) is a distinct mental state linked to a recurrent brain profile of globally positive connectivity during ongoing mentation

Peer-Reviewed Publication

UNIVERSITY OF LIEGE

Researchers from the GIGA CRC In vivo Imaging at the University of Liège (Belgium), the EPF Lausanne and the University of Geneva publish a study that shows that the phenomenology of "mind blanking" challenges the belief that the human mind is always thinking. The study is published in the journal Proceedings of the National Academy of Sciences.

We generally consider that our mind is full of thoughts when we are awake. Like a river stream always running, similarly we entertain our own dynamic mental stream: a thought can lead to another, relevant to what we do or not, ebbing between our inner life and the outer environment. How can the brain sustain such a thought-related mode constantly, though? A study just published in the Proceedings of the National Academy of Sciences indicates that it actually cannot, and that our brains also need to “go offline” for some moments, which we can experience as blanks in the mind.

Researchers from the University of Liège and EPF Lausanne & University of Geneva re-analyzed a previously collected dataset where healthy participants were reporting their mental state as this was before hearing an auditory probe (beep) while resting in the MRI scanner. The choices were among perceptions of the environment, stimulus-dependent thoughts, stimulus-independent thoughts, and mental absences. Functional images were being collected during this experience-sampling method. The researchers found that mind blanking episodes were reported quite rarely compared to the other states, and that they were re-appearing also scarcely across time. Using machine learning, the researchers further found that our brains during mind-blanking episodes organized in a way where all brain regions were communicating with each other at the same time. This ultra-connected brain pattern was further characterized by high amplitude of the fMRI global signal, which is a proxy of low cortical arousal. In other words, when reporting mind blanking our brains seem to be in a mode similar to that of deep sleep, only that we are awake.

“Mind blanking is a relatively new mental state within the study of spontaneous cognition. It opens exciting avenues about the underlying biological mechanisms that happen during waking life. It might be that the boundaries of sleep and wakefulness might not be that discrete as they appear to be after all”, says the principal investigator Dr. Demertzi Athena, FNRS researcher at GIGA ULiège. “The continuously and rapidly changing brain activity requires robust analysis methods to confirm the specific signature of mind blanking”, continues Dr. Van De Ville Dimitri.

The researchers claim that the rigid neurofunctional profile of mind blanking could account for the inability to report mental content due to the brain’s inability to differentiate signals in an informative way.  While waiting for the underlying mechanisms to be illuminated, this work suggests that instantaneous non-reportable mental events can happen during wakefulness, setting mind blanks as a prominent mental state during ongoing experience.

Scientific reference

Mortaheb, S., Van Calster, L., Raimondo, F., Klados, M. A., Boulakis, P. A., Georgoula, K., Majerus, S., Van De Ville, D., & Demertzi, A. (2022). Mind blanking is a distinct mental state linked to a recurrent brain profile of globally positive connectivity during ongoing mentation. Proceedings of the National Academy of Sciences, 119(41), e2200511119.

https://doi.org/10.1073/pnas.2200511119
https://www.pnas.org/doi/10.1073/pnas.2200511119

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JOURNAL

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.2200511119 

ARTICLE TITLE

Mind blanking is a distinct mental state linked to a recurrent brain profile of globally positive connectivity during ongoing mentation

ARTICLE PUBLICATION DATE

4-Oct-2022

Cat got your tongue: Cats distinguish between speech directed at them and humans

Peer-Reviewed Publication

SPRINGER

A small study has found that cats may change their behaviour when they hear their owner’s voice talking in a tone directed to them, the cats, but not when hearing the voice of a stranger or their owner’s voice directed at another person. The study of 16 cats is published in the journal Animal Cognition and adds to evidence that cats may form strong bonds with their owner.

Human tone is known to vary depending on who the speech is directed to, such as when talking to infants and dogs. The tone of human speech has been shown in previous studies to change when directed at cats, but less is known about how cats react to this.

Charlotte de Mouzon and colleagues from Université Paris Nanterre (Nanterre, France) investigated how 16 cats reacted to pre-recorded voices from both their owner and that of a stranger when saying phrases in cat-directed and human adult-directed tones.

The authors investigated three conditions, with the first condition changing the voice of the speaker from a stranger’s voice to the cat’s owner. The second and third conditions changed the tone used (cat-directed or adult-directed) for the cat’s owner or a stranger’s voice, respectively. The authors recorded and rated the behaviour intensity of cats reacting to the audio, checking for behaviours such as resting, ear moving, pupil dilation, and tail moving, amongst others. 

In the first condition, 10 out of the 16 cats showed a decrease in behaviour intensity as they heard three audio clips of a stranger’s voice calling them by their name. However, when hearing their owner’s voice their behaviour intensity significantly increased again. The cats displayed behaviours such as turning their ears to the speakers, increased movement around the room, and pupil dilation when hearing their owners’ voice. The authors suggest that the sudden rebound in behaviour indicates that cats could discriminate their owner’s voice from that of a stranger.

In the second condition, 10 cats (8 of which were the same from the first condition) decreased their behaviour as they heard audio from their owner in an adult-directed tone but significantly increased their behaviour when hearing the cat-directed tone from their owner. The change in behaviour intensity was not found in the third condition when a stranger was speaking in an adult-directed and cat-directed tone.

The authors observed that the cats can distinguish when their owner is talking in a cat-directed tone compared to an adult-directed tone, but did not react any differently when a stranger changes tone.  

The small sample size used in this study may not represent all cat behaviour but the authors propose that future research could investigate if their findings can be replicated in more socialised cats that are used to interacting with strangers.

The authors suggest that their findings bring a new dimension to cat-human relationships, with cat communication potentially relying on experience of the speaker’s voice. They conclude that one-to-one relationships are important for cats and humans to form strong bonds.

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Media Contact:

Tara Eadie
Press Officer
Springer Nature
T: +44 20 3426 3329 
E: tara.eadie@springernature.com

Notes to editor:

Discrimination of cat‑directed speech from human‑directed speech in a population of indoor companion cats (Felis catus)

Animal Cognition 2022

DOI: 10.1007/s10071-022-01674-w

For an embargoed copy of the research article, related images and video please contact Tara Eadie at Springer Nature.

1. After the embargo ends, the full paper will be available at: https://link.springer.com/article/10.1007/s10071-022-01674-w

2. Please name the journal in any story you write. If you are writing for the web, please link to the article.

Animal Cognition is an interdisciplinary journal publishing current research from various backgrounds and disciplines (ethology, behavioral ecology, animal behaviour and learning, cognitive sciences, comparative psychology and evolutionary psychology) on all aspects of animal (and human) cognition in an evolutionary framework.

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JOURNAL

Animal Cognition

DOI

10.1007/s10071-022-01674-w 

Machine learning enables an 'almost perfect' diagnosis of an elusive global killer

by Chan Zuckerberg Biohub

Credit: Pixabay/CC0 Public Domain

Sepsis, the overreaction of the immune system in response to an infection, causes an estimated 20% of deaths globally and as many as 20 to 50% of U.S. hospital deaths each year. Despite its prevalence and severity, however, the condition is difficult to diagnose and treat effectively.

The disease can cause decreased blood flow to vital organs, inflammation throughout the body, and abnormal blood clotting. Therefore, if sepsis isn't recognized and treated quickly, it can lead to shock, organ failure, and death. But it can be difficult to identify which pathogen is causing sepsis, or whether an infection is in the bloodstream or elsewhere in the body. And in many patients with symptoms that resemble sepsis, it can be challenging to determine whether they truly have an infection at all.

Now, researchers at the Chan Zuckerberg Biohub (CZ Biohub), the Chan Zuckerberg Initiative (CZI), and UC San Francisco (UCSF) have developed a new diagnostic method that applies machine learning to advanced genomics data from both microbe and host—to identify and predict sepsis cases. As reported on October 20, 2022 in Nature Microbiology, the approach is surprisingly accurate, and has the potential to far exceed current diagnostic capabilities.

"Sepsis is one of the top 10 public health issues facing humanity," said senior author Chaz Langelier, M.D., Ph.D., an associate professor of medicine in UCSF's Division of Infectious Diseases and a CZ Biohub Investigator. "One of the key challenges with sepsis is diagnosis. Existing diagnostic tests are not able to capture the dual-sided nature of the disease—the infection itself and the host's immune response to the infection."

Current sepsis diagnostics focus on detecting bacteria by growing them in culture, a process that is "essential for appropriate antibiotic therapy, which is critical for sepsis survival," according to the researchers behind the new method. But culturing these pathogens is time-consuming and doesn't always correctly identify the bacterium that is causing the infection. Similarly for viruses, PCR tests can detect that viruses are infecting a patient but don't always identify the particular virus that's causing sepsis.

"This results in clinicians being unable to identify the cause of sepsis in an estimated 30 to 50% of cases," Langelier said. "This also leads to a mismatch in terms of the antibiotic treatment and the pathogen causing the problem."

In the absence of a definitive diagnosis, doctors often prescribe a cocktail of antibiotics in an effort to stop the infection, but the overuse of antibiotics has led to increased antibiotic resistance worldwide. "As physicians, we never want to miss a case of infection," said Carolyn Calfee, M.D., M.A.S., a professor of medicine and anesthesia at UCSF and co-senior author of the new study. "But if we had a test that could help us accurately determine who doesn't have an infection, then that could help us limit antibiotic use in those cases, which would be really good for all of us."

Eliminating ambiguity

The researchers analyzed whole blood and plasma samples from more than 350 critically ill patients who had been admitted to UCSF Medical Center or the Zuckerberg San Francisco General Hospital between 2010 and 2018.

But rather than relying on cultures to identify pathogens in these samples, a team led by CZ Biohub scientists Norma Neff, Ph.D., and Angela Pisco, Ph.D., instead used metagenomic next-generation sequencing (mNGS). This method identifies all the nucleic acids or genetic data present in a sample, then compares those data to reference genomes to identify the microbial organisms present. This technique allows scientists to identify genetic material from entirely different kingdoms of organisms—whether bacteria, viruses, or fungi—that are present in the same sample.

However, detecting and identifying the presence of a pathogen alone isn't enough for accurate sepsis diagnosis, so the Biohub researchers also performed transcriptional profiling—which quantifies gene expression—to capture the patient's response to infection.

Next they applied machine learning to the mNGS and transcriptional data to distinguish between sepsis and other critical illnesses and thus confirm the diagnosis. Katrina Kalantar, Ph.D., a lead computational biologist at CZI and co-first author of the study, created an integrated host-microbe model trained on data from patients in whom either sepsis or non-infectious systemic inflammatory illnesses had been established, which enabled sepsis diagnosis with very high accuracy.

"We developed the model by looking at a bunch of metagenomics data alongside results from traditional clinical tests," Kalantar explained. To start, the researchers identified changes in gene expression between patients with confirmed sepsis and non-infectious systemic inflammatory conditions that appear clinically similar, then used machine learning to identify the genes that could best predict those changes.

The researchers found that when traditional bacterial culture identified a sepsis-causing pathogen, there was usually an overabundance of genetic material from that pathogen in the corresponding plasma sample analyzed by mNGS. With that in mind, Kalantar programmed the model to identify organisms present in disproportionately high abundance compared to other microbes in the sample, and to then compare those to a reference index of well-known sepsis-causing microbes.

"In addition to that, we also noted any viruses that were detected, even if they were at lower levels, because those really shouldn't be there," Kalantar explained. "With this relatively straightforward set of rules, we were able to do pretty well."

'Almost perfect' performance

The researchers found that the mNGS method and their corresponding model worked better than expected: They were able to identify 99% of confirmed bacterial sepsis cases, 92% of confirmed viral sepsis cases, and were able to predict sepsis in 74% of clinically suspected cases that hadn't been definitively diagnosed.

"We were expecting good performance, or even great performance, but this was almost perfect," said Lucile Neyton, Ph.D., a postdoctoral researcher in the Calfee lab and co-first author of the study. "By using this approach, we get a pretty good idea of what is causing the disease, and we know with relatively high confidence if a patient has sepsis or not."

The team was also excited to discover that they could use this combined host-response and microbe detection method to diagnose sepsis using plasma samples, which are routinely collected from most patients as part of standard clinical care. "The fact that you can actually identify sepsis patients from this widely available, easy-to-collect sample type has big implications in terms of practical utility," Langelier said.

The idea for the work stemmed from previous research by Langelier, Kalantar, Calfee, UCSF researcher and CZ Biohub President Joe DeRisi, Ph.D., and their colleagues, in which they used mNGS to effectively diagnose lower respiratory tract infections in critically ill patients. Because the method worked so well, "we wanted to see if the same type of approach could work in the context of sepsis," said Kalantar.

Broader implications

The team hopes to build upon this successful diagnostic technique by developing a model that can also predict antibiotic resistance from pathogens detected with this method. "We've had some success doing that for respiratory infections, but no one has come up with a good approach for sepsis," Langelier said.

Furthermore, the researchers hope to eventually be able to predict outcomes of patients with sepsis, "such as mortality or length of stay in the hospital, which would provide key information that would allow clinicians to better care for their patients and match resources to the patients who need them the most," Langelier said.

"There's a lot of potential for novel sequencing approaches such as this to help us more precisely identify the causes of a patient's critical illness," added Calfee. "If we can do that, it's the first step towards precision medicine and understanding what's going on at an individual patient level."Consumer health: What do you know about sepsis?

More information: Katrina L. Kalantar et al, Integrated host-microbe plasma metagenomics for sepsis diagnosis in a prospective cohort of critically ill adults, Nature Microbiology (2022). DOI: 10.1038/s41564-022-01237-2

Journal information: Nature Microbiology 

Provided by Chan Zuckerberg Biohub

MY FATHER DIED OF SEPSIS FROM AN INFECTION CAUSED AT THE HOSPITAL USING A BAD SALINE SOLUTION FOR HIS HIP JOINT

Underground microbes may have swarmed ancient Mars

This image captured by the United Arab Emirates' "Amal" ("Hope") probe shows the planet 

Mars on Feb. 10, 2021. Ancient Mars may have had an environment capable of harboring 

an underground world teeming with microscopic organisms. That's according to French 

scientists who published their findings Monday, Oct. 10, 2022.

 Credit: Mohammed bin Rashid Space Center/UAE Space Agency, via AP, File

Ancient Mars may have had an environment capable of harboring an underground world teeming with microscopic organisms, French scientists reported Monday.

But if they existed, these simple life forms would have altered the atmosphere so profoundly that they triggered a Martian Ice Age and snuffed themselves out, the researchers concluded.

The findings provide a bleak view of the ways of the cosmos. Life—even simple life like microbes—"might actually commonly cause its own demise," said the study's lead author, Boris Sauterey, now a post-doctoral researcher at Sorbonne University.

The results "are a bit gloomy, but I think they are also very stimulating.," he said in an email. "They challenge us to rethink the way a biosphere and its planet interact."

In a study in the journal Nature Astronomy, Sauterey and his team said they used climate and terrain models to evaluate the habitability of the Martian crust some 4 billion years ago when the red planet was thought to be flush with water and much more hospitable than today.

They surmised that hydrogen-gobbling, methane-producing microbes might have flourished just beneath the surface back then, with several inches (a few tens of centimeters) of dirt, more than enough to protect them against harsh incoming radiation. Anywhere free of ice on Mars could have been swarming with these organisms, according to Sauterey, just as they did on early Earth.

Early Mars' presumably moist, warm climate, however, would have been jeopardized by so much hydrogen sucked out of the thin, carbon dioxide-rich atmosphere, Sauterey said. As temperatures plunged by nearly minus 400 degrees Fahrenheit (minus 200 degrees Celsius), any organisms at or near the surface likely would have buried deeper in an attempt to survive.

This image made available by NASA shows the Jezero Crater area on the planet Mars, captured by the Mars Reconnaissance Orbiter. Ancient Mars may have had an environment capable of harboring an underground world teeming with microscopic organisms. That's according to French scientists who published their findings, Monday, Oct. 10, 2022. Credit: NASA/JPL-Caltech/USGS via AP, File

By contrast, microbes on Earth may have helped maintain temperate conditions, given the nitrogen-dominated atmosphere, the researchers said.

The SETI Institute's Kaveh Pahlevan said future models of Mars' climate need to consider the French research.

Pahlevan led a separate recent study suggesting Mars was born wet with warm oceans lasting millions of years. The atmosphere would have been dense and mostly hydrogen back then, serving as a heat-trapping greenhouse gas that eventually was transported to higher altitudes and lost to space, his team concluded.

The French study investigated the climate effects of possible microbes when Mars' atmosphere was dominated by carbon dioxide and so is not applicable to the earlier times, Pahlevan said.

"What their study makes clear, however, is that if (this) life were present on Mars" during this earlier period, "they would have had a major influence on the prevailing climate," he added in an email.

The best places to look for traces of this past life? The French researchers suggest the unexplored Hellas Planita, or plain, and Jezero Crater on the northwestern edge of Isidis Planita, where NASA's Perseverance rover currently is collecting rocks for return to Earth in a decade.

Next on Sauterey's to-do list: looking into the possibility that microbial life could still exist deep within Mars.

"Could Mars still be inhabited today by micro-organisms descending from this primitive biosphere?" he said. "If so, where?"New clues about early atmosphere on Mars suggest a wet planet capable of supporting life

More information: Boris Sauterey, Early Mars habitability and global cooling by H2-based methanogens, Nature Astronomy (2022). DOI: 10.1038/s41550-022-01786-w. www.nature.com/articles/s41550-022-01786-w

Journal information: Nature Astronomy 

© 2022 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed without permission.

Something Buried For Centuries Has Just Been Uncovered - Intro To 2001 Movie Ghost Of Mars

 

GHOSTS OF MARS (The Horrific Martian Spirits & Ending) EXPLAINED

 

Research finds unprecedented levels of insects damaging plants

by University of Wyoming

Lauren Azevedo-Schmidt searches for fossilized plants in Wyoming’s Hanna Basin in a 

deposit that is about 60 million years old. She and other researchers compared fossil 

leaves with modern samples and found higher rates of insect damage today. 

Credit: Lauren Azevedo-Schmidt

Insects today are causing unprecedented levels of damage to plants, even as insect numbers decline, according to new research led by University of Wyoming scientists.

The first-of-its-kind study compares insect herbivore damage of modern-era plants with that of fossilized leaves from as far back as the Late Cretaceous period, nearly 67 million years ago. The findings appear in the journal Proceedings of the National Academy of Sciences.

"Our work bridges the gap between those who use fossils to study plant-insect interactions over deep time and those who study such interactions in a modern context with fresh leaf material," says the lead researcher, UW Ph.D. graduate Lauren Azevedo-Schmidt, now a postdoctoral research associate at the University of Maine. "The difference in insect damage between the modern era and the fossilized record is striking."

Azevedo-Schmidt conducted the research along with UW Department of Botany and Department of Geology and Geophysics Professor Ellen Currano, and Assistant Professor Emily Meineke of the University of California-Davis.

The study examined fossilized leaves with insect feeding damage from the Late Cretaceous through the Pleistocene era, a little over 2 million years ago, and compared them with leaves collected by Azevedo-Schmidt from three modern forests. The detailed research looked at different types of damage caused by insects, finding marked increases in all recent damage compared to the fossil record.

This fossil leaf from Wyoming’s Hanna Basin, about 54 million years old, shows damage

 by insects. Credit: Lauren Azevedo-Schmidt

"Our results demonstrate that plants in the modern era are experiencing unprecedented levels of insect damage, despite widespread insect declines," wrote the scientists, who suggest that the disparity can be explained by human activity.

More research is necessary to determine the precise causes of increased insect damage to plants, but the scientists say a warming climate, urbanization and introduction of invasive species likely have had a major impact.

"We hypothesize that humans have influenced (insect) damage frequencies and diversities within modern forests, with the most human impact occurring after the Industrial Revolution," the researchers wrote. "Consistent with this hypothesis, herbarium specimens from the early 2000s were 23 percent more likely to have insect damage than specimens collected in the early 1900s, a pattern that has been linked to climate warming."

But climate change doesn't fully explain the increase in insect damage, they say.

"This research suggests that the strength of human influence on plant-insect interactions is not controlled by climate change alone, but rather, the way in which humans interact with the terrestrial landscape," the researchers concluded.

Beetle in the coconut: Fossil find sheds new light on Neotropical rainforests

More information: Azevedo-Schmidt, Lauren, Insect herbivory within modern forests is greater than fossil localities, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2202852119. doi.org/10.1073/pnas.2202852119

Journal information: Proceedings of the National Academy of Sciences 

Provided by University of Wyoming 

DNA found in sediment reveals that ancient artificial islands may have been high-status homes

by Antiquity

Crannog in Lough na Cranagh, near Fair Head, Northern Ireland. Credit: Antony Brown

Researchers have recovered DNA from the sediments surrounding ancient artificial islands, known as crannogs, in Britain and Ireland. These results, along with environmental and biochemical data in these sediments, show the structures were once used by elites.

Crannogs were built and occupied from the Neolithic, 4000–2200 BC, through to the 16th century AD. Hundreds have been found, mostly in Scotland, Ireland, and Northern Ireland.

However, the aquatic location of crannogs makes them difficult for archaeologists to excavate. So Professor Antony Brown, from UiT Arctic University of Norway, and an interdisciplinary team from across the UK set out to take samples from lake sediments instead.

Previous research had recovered environmental data, like pollen, from sediment cores obtained near crannogs. Material gets washed off the island and deposited layer by layer in the lake, so cores of these sediments reveal crannog conditions over time.

Now, Professor Brown and the team have also been able to recover DNA from these cores, known as "sedaDNA." This was combined with analysis of other material in the sediment to build an integrated picture of the crannogs. Their work is published in the journal Antiquity.

For this research, the team analyzed sediment cores from around crannogs in White Loch of Myrton, Scotland, and Lough Yoan, Ireland. Radiocarbon dating of the cores revealed the crannog in White Loch was built in the Iron Age, around 400 BC, whilst Lough Yoan's dates to the medieval period. They found both were abandoned and re-occupied multiple times.

Replica crannog in Waterford, Ireland. Credit: Antony Brown

The integrated analysis showed that the crannogs were important places, likely high-status homes, stocked with resources. The team found pollen from bracken, for bedding, as well as signs crafting took place on the islands.

Additionally, sedaDNA from cows, sheep, and goats indicated that animals were kept on the crannogs. At one of the Lough Yoan crannogs, bone fragments suggest that were butchered on-site in high quantities, likely for feasts. This supports previous research suggesting some crannogs were compounds used by the elite, perhaps for ceremonial occasions.

The team also found that the cost of supplying the crannogs with these resources meant they were linked to dramatic changes in the local area. Changes in pollen and plant sedaDNA indicated crannog construction was associated with deforestation, likely to provide materials and clear farmland. Meanwhile, waste from the inhabitants polluted the lakes, leading to human impact on lake ecosystems as early as the Iron Age.

As such, this research sheds new light on life on crannogs and also shows how this integrated method of studying sediment cores provides insight into otherwise hard-to-study waterside sites. This approach, incorporating sedaDNA, provides researchers with a powerful new tool.

The team are already expanding to study other crannogs. These unique structures are under threat from erosion and other environmental changes.

New evidence suggests Scottish crannogs thousands of years older than thought

More information: Antony G. Brown et al, New integrated molecular approaches for investigating lake settlements in north-western Europe, Antiquity (2022). DOI: 10.15184/aqy.2022.70

Journal information: Antiquity 

Provided by Antiquity

ALCHEMY

Nanomaterial from the Middle Ages

by Barbara Vonarburg, Paul Scherrer Institute

PXCT 3D images of the 35-year old Zwischgold sample showing the addition of (a) Au, (b) Ag (with transparent voids), (c) “silver corrosion products”, and (d) other segments. (e) Stack plot of the depth profile of the single-layered section of the sample, aligned to the main layer of the Au segment. Credit: Nanoscale (2022). DOI: 10.1039/D2NR03367D

To gild sculptures in the late Middle Ages, artists often applied ultra-thin gold foil supported by a silver base layer. For the first time, scientists at the Paul Scherrer Institute PSI have managed to produce nanoscale 3D images of this material, known as Zwischgold. The pictures show this was a highly sophisticated medieval production technique and demonstrate why restoring such precious gilded artifacts is so difficult.

The samples examined at the Swiss Light Source SLS using one of the most advanced microscopy methods were unusual even for the highly experienced PSI team: minute samples of materials taken from an altar and wooden statues originating from the fifteenth century. The altar is thought to have been made around 1420 in Southern Germany and stood for a long time in a mountain chapel on Alp Leiggern in the Swiss canton of Valais.

Today it is on display at the Swiss National Museum (Landesmuseum Zürich). In the middle you can see Mary cradling Baby Jesus. The material sample was taken from a fold in the Virgin Mary's robe. The tiny samples from the other two medieval structures were supplied by Basel Historical Museum.

The material was used to gild the sacred figures. It is not actually gold leaf, but a special double-sided foil of gold and silver where the gold can be ultra-thin because it is supported by the silver base. This material, known as Zwischgold (part-gold) was significantly cheaper than using pure gold leaf.

"Although Zwischgold was frequently used in the Middle Ages, very little was known about this material up to now," says PSI physicist Benjamin Watts: "So we wanted to investigate the samples using 3D technology which can visualize extremely fine details."

Although other microscopy techniques had been used previously to examine Zwischgold, they only provided a 2D cross-section through the material. In other words, it was only possible to view the surface of the cut segment, rather than looking inside the material. The scientists were also worried that cutting through it may have changed the structure of the sample.

The advanced microscopy imaging method used today, ptychographic tomography, provides a 3D image of Zwischgold's exact composition for the first time.

X-rays generate a diffraction pattern

The PSI scientists conducted their research using X-rays produced by the Swiss Light Source SLS. These produce tomographs displaying details in the nanoscale range—millionths of a millimeter, in other words.

"Ptychography is a fairly sophisticated method, as there is no objective lens that forms an image directly on the detector," Watts explains. Ptychography actually produces a diffraction pattern of the illuminated area, in other words an image with points of differing intensity.

By manipulating the sample in a precisely defined manner, it is possible to generate hundreds of overlapping diffraction patterns. "We can then combine these diffraction patterns like a sort of giant Sudoku puzzle and work out what the original image looked like," says the physicist. A set of ptychographic images taken from different directions can be combined to create a 3D tomogram.

The advantage of this method is its extremely high resolution. "We knew the thickness of the Zwischgold sample taken from Mary was of the order of hundreds of nanometers," Watts explains. "So we had to be able to reveal even tinier details."

The scientists achieved this using ptychographic tomography, as they report in their latest article in the journal Nanoscale. "The 3D images clearly show how thinly and evenly the gold layer is over the silver base layer," says Qing Wu, lead author of the publication.

The art historian and conservation scientist completed her Ph.D. at the University of Zurich, in collaboration with PSI and the Swiss National Museum. "Many people had assumed that technology in the Middle Ages was not particularly advanced," Wu comments. "On the contrary: this was not the Dark Ages, but a period when metallurgy and gilding techniques were incredibly well developed."

Secret recipe revealed

Unfortunately there are no records of how Zwischgold was produced at the time. "We reckon the artisans kept their recipe secret," says Wu. Based on nanoscale images and documents from later epochs, however, the art historian now knows the method used in the 15th century: first the gold and the silver were hammered separately to produce thin foils, whereby the gold film had to be much thinner than the silver.

Then the two metal foils were worked on together. Wu describes the process: "This required special beating tools and pouches with various inserts made of different materials into which the foils were inserted," Wu explains. This was a fairly complicated procedure that required highly skilled specialists.

"Our investigations of Zwischgold samples showed the average thickness of the gold layer to be around 30 nanometers, while gold leaf produced in the same period and region was approximately 140 nanometers thick," Wu explains. "This method saved on gold, which was much more expensive." At the same time, there was also a very strict hierarchy of materials: gold leaf was used to make the halo of one figure, for example, while Zwischgold was used for the robe.

Because this material has less of a sheen, the artists often used it to color the hair or beards of their statues. "It is incredible how someone with only hand tools was able to craft such nanoscale material," Watts says. Medieval artisans also benefited from a unique property of gold and silver crystals when pressed together: their morphology is preserved across the entire metal film. "A lucky coincidence of nature that ensures this technique works," says the physicist.

Golden surface turns black

The 3D images do bring to light one drawback of using Zwischgold, however: the silver can push through the gold layer and cover it. The silver moves surprisingly quickly—even at room temperature. Within days, a thin silver coating covers the gold completely. At the surface the silver comes into contact with water and sulfur in the air, and corrodes.

"This makes the gold surface of the Zwischgold turn black over time," Watts explains. "The only thing you can do about this is to seal the surface with a varnish so the sulfur does not attack the silver and form silver sulfide." The artisans using Zwischgold were aware of this problem from the start. They used resin, glue or other organic substances as a varnish. "But over hundreds of years this protective layer has decomposed, allowing corrosion to continue," Wu explains.

The corrosion also encourages more and more silver to migrate to the surface, creating a gap below the Zwischgold. "We were surprised how clearly this gap under the metal layer could be seen," says Watts. Especially in the sample taken from Mary's robe, the Zwischgold had clearly come away from the base layer.

"This gap can cause mechanical instability, and we expect that in some cases it is only the protective coating over the Zwischgold that is holding the metal foil in place," Wu warns. This is a massive problem for the restoration of historical artifacts, as the silver sulfide has become embedded in the varnish layer or even further down.

"If we remove the unsightly products of corrosion, the varnish layer will also fall away and we will lose everything," says Wu. She hopes it will be possible in future to develop a special material that can be used to fill the gap and keep the Zwischgold attached. "Using ptychographic tomography, we could check how well such a consolidation material would perform its task," says the art historian.Maintaining the structure of gold and silver in alloys

More information: Qing Wu et al, A modern look at a medieval bilayer metal leaf: nanotomography of Zwischgold, Nanoscale (2022). DOI: 10.1039/D2NR03367D

Journal information: Nanoscale 

Provided by Paul Scherrer Institute