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The bulging, equator-belted midsection of Earth currently teems with a greater diversity of life than anywhere else — a biodiversity that generally wanes when moving from the tropics to the mid-latitudes and the mid-latitudes to the poles.
As well-accepted as that gradient is, though, ecologists continue to grapple with the primary reasons for it. New research from the University of Nebraska-Lincoln, Yale University and Stanford University suggests that temperature can largely explain why the greatest variety of aquatic life resides in the tropics — but also why it has not always and, amid record-fast global warming, soon may not again.
Published May 6 in the journal Current Biology, the study estimates that marine biodiversity tends to increase until the average surface temperature of the ocean reaches about 65 degrees Fahrenheit, beyond which that diversity slowly declines.
During intervals of Earth’s history when the maximum surface temperature was lower than 80 degrees Fahrenheit, the greatest biodiversity was found around the equator, the study concluded. But when that maximum exceeded 80 degrees, marine biodiversity ebbed in the tropics, where those highest temperatures would have manifested, while peaking in waters at the mid-latitudes and the poles.
Marine life that could travel considerable distances likely migrated north or south from the tropics during periods of extreme heat, said co-author Will Gearty, a postdoctoral researcher of biological sciences at Nebraska. Stationary or slower-moving animals, such as sponges and sea stars, may have instead faced extinction.
“People have always theorized that the tropics are a cradle of diversity — that it pops up and then is protected there,” Gearty said. “There’s also this idea that … there’s lots of migration toward the tropics, but not away from it. All of that centers around the idea that the highest diversity will always be in the tropics. And that’s not what we see as we go back in time.”
Gearty, Yale’s Thomas Boag and Stanford’s Richard Stockey went back about 145 million years, compiling estimated temperatures and fossil records of mollusks — snails, clams, cephalopods and the like — from 24 horizontal bands of Earth that were equal in surface area. The trio chose mollusk records for multiple reasons: They live (and lived) around the globe, in large enough numbers to accommodate statistical analyses, with hard enough shells to yield identifiable fossils, with enough variation that their diversity trends might generalize to fish, corals, crustaceans and an array of other marine animals.

Heart disease can take a number of forms, but some types of heart disease, such as asymptomatic low ejection fraction, can be hard to recognize, especially in the early stages when treatment would be most effective. The ECG AI-Guided Screening for Low Ejection Fraction, or EAGLE, trial set out to determine whether an artificial intelligence (AI) screening tool developed to detect low ejection fraction using data from an EKG could improve the diagnosis of this condition in routine practice. Study findings are published in Nature Medicine.
Systolic low ejection fraction is defined as the heart’s inability to contract strongly enough with each beat to pump at least 50% of the blood from its chamber. An echocardiogram can readily diagnose low ejection fraction, but this time-consuming imaging test requires more resources than a 12-lead EKG, which is fast, inexpensive and readily available. The AI-enabled EKG algorithm was tested and developed through a convolutional neural network and validated in subsequent studies.
The EAGLE trial took place in 45 medical institutions in Minnesota and Wisconsin, including rural clinics, and community and academic medical centers. In all, 348 primary care clinicians from 120 medical care teams were randomly assigned to usual care or intervention. The intervention group was alerted to a positive screening result for low ejection fraction via the electronic health record, prompting them to order an echocardiogram to confirm.
“The AI-enabled EKG facilitated the diagnosis of patients with low ejection fraction in a real-world setting by identifying people who previously would have slipped through the cracks,” says Peter Noseworthy, M.D., a Mayo Clinic cardiac electrophysiologist. Dr. Noseworthy is senior author on the study.
In eight months, 22,641 adult patients had an EKG under the care of the clinicians in the trial. The AI found positive results in 6% of the patients. The proportion of patients who received an echocardiogram was similar overall, but among patients with a positive screening result, a higher percentage of intervention patients received an echocardiogram.
“The AI intervention increased the diagnosis of low ejection fraction overall by 32% relative to usual care. Among patients with a positive AI result, the relative increase of diagnosis was 43%,” says Xiaoxi Yao, Ph.D., a health outcomes researcher in cardiovascular diseases at Mayo Clinic and first author on the study. “To put it in absolute terms, for every 1,000 patients screened, the AI screening yielded five new diagnoses of low ejection fraction over usual care.”
“With EAGLE, the information was readily available in the electronic health record, and care teams could see the results and decide how to use that information,” says Dr. Noseworthy. “The takeaway is that we are likely to see more AI use in the practice of medicine as time goes on. It’s up to us to figure how to use this in a way that improves care and health outcomes but does not overburden front-line clinicians.”
Also, the EAGLE trial used a positive deviance approach to evaluate the top five care team users and the top five nonusers of the AI screening information. Dr. Yao says this cycle of learning and feedback from physicians will demonstrate ways of improving adaptation and application of AI technology in the practice.
EAGLE is one of the first large-scale trials to demonstrate value of AI in routine practice. The low ejection fraction algorithm, which has received Food and Drug Administration breakthrough designation, is one of several algorithms developed by Mayo and licensed to Anumana Inc., a new company focusing on unlocking hidden biomedical knowledge to enable early detection as well as accelerate treatment of heart disease. The low ejection fraction algorithm was also previously licensed to Eko Devices Inc., specifically for hand-held devices that are externally applied to the chest.
The EAGLE trial was funded by Mayo Clinic’s Robert D. and Patricia E. Kern Center for the Science of Health Care Delivery, in collaboration with the departments of Cardiovascular Medicine and Family Medicine, and the Division of Community Internal Medicine.
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Materials provided by Mayo Clinic. Original written by Terri Malloy. Note: Content may be edited for style and length.

Neurodegenerative diseases such as Alzheimer’s, Parkinson’s and ALS affect millions of adults, but scientists still do not know what causes these diseases, which poses a significant roadblock to developing treatments or preventative measures.
Recent research suggests that people with these conditions exhibit changes in the bacterial composition of their digestive tract. However, given the vast diversity of microbes found in the human body, identifying which bacteria may be associated with neurodegeneration is like finding a needle in a haystack.
Seeking that proverbial needle, scientists at the University of Florida are looking in an unexpected place: the digestive tract of a tiny, translucent worm called Caenorhabditis elegans.
New research published in PLOS Pathogens establishes, for the first time, a link between specific bacteria species and physical manifestations of neurodegenerative diseases. The study’s lead author is Alyssa Walker, a microbiology and cell science doctoral candidate in the UF/IFAS College of Agricultural and Life Sciences.
“Looking at the microbiome is a relatively new approach to investigating what causes neurodegenerative diseases. In this study, we were able to show that specific species of bacteria play a role in the development of these conditions,” said Daniel Czyz, Walker’s dissertation advisor.
Czyz is the senior author of the study and an assistant professor in the UF/IFAS department of microbiology and cell science.

Strategic vaccine delivery is critical to reducing COVID-19 transmission, mortality and long-term health impacts. A study published in PLOS Computational Biology by Sam Moore, Matt Keeling and colleagues at University of Warwick, United Kingdom suggests that prioritizing vaccine delivery to older age groups and the medically vulnerable has the greatest impact in minimizing loss of life.
While older people are more likely to experience serious health outcomes related to COVID-19 infections, younger age groups contribute significantly to disease transmission and spread. In order to test the efficacy of different vaccination strategies on minimizing deaths and hospitalisations, researchers built an age-structured model that simulated the spread of SARS-CoV-2 within different regions in the United Kingdom. The authors then used the model to test multiple different scenarios, including variations in vaccine efficacy using observational data on comorbidities and social-distancing measures in the United Kingdom.
The models showed that vaccine strategies prioritizing older age groups first most effectively mitigated deaths and lost quality of life years, despite the significant role of younger groups in disease spread. Since the study’s completion in 2020, data has become available for the key assumption on vaccine uptake and specific vaccine characteristics, however the general conclusions of the study remain relevant. Additionally, the research has already helped guide UK policy makers in the development of an effective COVID-19 vaccination programs, including the formation of the Joint Committee for Vaccination and Immunisation’s priority groups that have been used for vaccine delivery.
According to the authors, “While the ultimate success of any vaccination scheme will be highly contingent on the characteristics of the vaccine itself and the level of population uptake, as vaccines are developed which mitigate the disease, it is of great importance that they are delivered in an optimal manner — reducing mortality and healthcare demands. In all scenarios we find vaccinating the most elderly and vulnerable first to have the greatest impact.”
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Scientists in China and Germany have designed an artificial color-changing material that mimics chameleon skin, with luminogens (molecules that make crystals glow) organized into different core and shell hydrogel layers instead of one uniform matrix. The findings, published May 6 in the journal Cell Reports Physical Science, demonstrate that a two-luminogen hydrogel chemosensor developed with this design can detect seafood freshness by changing color in response to amine vapors released by microbes as fish spoils. The material may also be used to advance the development of stretchable electronics, dynamic camouflaging robots, and anticounterfeiting technologies.
“This novel core-shell layout does not require a careful choice of luminogen pairs, nor does it require an elaborate design and regulation of the complex photophysical interactions between different luminogens,” says Tao Chen, a professor at the Ningbo Institute of Materials Technology and Engineering at the Chinese Academy of Sciences and an author of the study. “These advantages are important to the future construction of robust multicolor material systems with as-yet-unachieved performance.”
While scientists have long envisioned developing soft materials that can fluctuate between a wide range of fluorescent colors with ease, synthetic materials are rarely able to change hue as artfully as chameleons do.
“Most artificial color-changing soft materials have been prepared by simultaneously incorporating two or more responsive luminogens into one single elastomer or hydrogel matrix,” says Chen. “On the other hand, the organization of different iridophores into two superposed core-shell structured layers constitutes an evolutionary novelty for panther chameleons that allows their skins to display complex structural colors.”
To determine whether artificial color-changing materials could be imbued with the natural core-shell structure of chameleon skin, Wei Lu, a researcher at the Ningbo Institute of Materials Technology and Engineering at the Chinese Academy of Sciences, and colleagues developed a multi-luminogen layered hydrogen system from the inside out. First, the researchers synthesized a red fluorescent core hydrogel, which would serve as a template for the other layers. This core hydrogel was incubated in various aqueous Europium solutions, after which the gel was incubated in a growth solution containing sodium alginate and responsive blue/green fluorescent polymers. Spontaneous diffusion of Europium ions from the core hydrogel into the surrounding solution triggered the formation of blue and green hydrogel layers.
Because of the way that the core and shell layers of the hydrogels overlapped, they could change from red to blue or green when triggered by changes in temperature or pH. The authors also note that the emission color of the blue and green fluorescent layers could be adjusted, enabling the material to display colors from nearly the full visible spectrum.
“The proposed diffusion-induced interfacial polymerization to prepare core-shell materials proves to be general,” says Chen. “It is thus highly expected that the proposed synthetic strategy could be expanded to produce other soft color-changing materials, such as smart hydrogels or elastomers with stimuli-responsive structural color or pigment color change.”
To test the abilities of a chemosensor crafted from a two-luminogen hydrogel to detect seafood freshness, Lu and colleagues sealed test strips made from the material in boxes with fresh shrimp or fish for 50 hours. The test strip stored with seafood at less than -10?C barely changed from its original red fluorescent color, indicating that the food was still fresh, while the test strip stored with seafood at 30?C shifted to a vivid green hue, indicating that the food had spoiled.
Chen suggests that both the novel core-shell hydrogels and the diffusion-induced interfacial polymerization strategy used to make them could prove useful in a diverse range of scientific fields, including robotics.
“In the near future, we plan to utilize the developed chameleon skin-like core-shell hydrogels to prepare biomimetic soft camouflaging skins, which can be used to mimic the diverse color-changing functions of living organisms’ skins and to help achieve desirable active camouflage, display and alarm functions in robots,” says Chen.
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Robin Harper, an administrative assistant at a preschool in Martha’s Vineyard, grew up showering every day. “It’s what you did,” she said.But when the pandemic forced her indoors and away from the public, she started showering once a week. The new practice felt environmentally virtuous, practical and freeing — and it has stuck.“Don’t get me wrong — I like showers,” said Ms. Harper, 43, who has returned to work. “But it’s one thing off my plate. I’m a mom, I work full-time, and it’s one less thing I have to do.”The pandemic has upended the use of zippered pants and changed many people’s eating and drinking habits. And there are now indications that it has caused some Americans to become more spartan when it comes to ablutions.Parents say that their teenage children are forgoing daily showers. After the British news media reported on a YouGov survey showing that 17 percent of people in Britain had abandoned daily showers during the pandemic, many on Twitter said they had done the same.Heather Whaley, 49, a writer in Redding, Conn., said that her shower use had dropped 20 percent in the past year. After the pandemic forced her into lockdown, she said, she began considering why she was showering every day.“Do I need to? Do I want to?” she said. “The act of taking a shower became less a matter of function and more of a matter of doing something for myself that I enjoyed.”(An earlier version of this item misspelled the name of the town.)

The American public’s willingness to get a Covid vaccine is reaching a saturation point among adults, and many parents do not plan to vaccinate their children, a new national survey suggests.Only 9 percent of respondents said that they had not yet gotten a shot but intended to do so, according to the survey, which was published in the April edition of the Kaiser Family Foundation’s Vaccine Monitor.Three in 10 parents said they planned to vaccinate their children as soon as they could. No vaccine is yet available in the U.S. for children; the Pfizer-BioNTech vaccine is expected to be authorized soon for those aged 12 to 15.The survey found that public confidence in the Johnson & Johnson vaccine has plummeted since health authorities suspended using it for 10 days to examine possible links to a rare, dangerous blood clotting problem.But it also found significant progress in persuading Republicans, who have been among the most hesitant, to be vaccinated.The findings highlight the challenges ahead for the Biden administration’s efforts to persuade hesitant people to take the vaccine, even as a growing number of scientists and public health experts have concluded that it is unlikely that the country will reach herd immunity.Overall, slightly more than half of a nationally representative sample of 2,097 adults surveyed said they had gotten at least one dose of the vaccine, a finding that matches data from the Centers for Disease Control and Prevention.The administration announced steps on Tuesday to encourage more pop-up and mobile vaccine clinics and to distribute shots to local pharmacies as well as primary care doctors and pediatricians.

St. Jude Children’s Research Hospital scientists have developed an integrated, high-throughput system to better understand and possibly manipulate gene expression for treatment of disorders such as sickle cell disease and beta thalassemia. The research appears today in the journal Nature Genetics.
Researchers used the system to identify dozens of DNA regulatory elements that act together to orchestrate the switch from fetal to adult hemoglobin expression. The method can also be used to study other diseases that involve gene regulation.
Regulatory elements, also called genetic switches, are scattered throughout non-coding regions of DNA. These regions do not encode genes and make up about 98% of the genome. The elements have a variety of names — enhancer, repressor, insulator and more — but the specific genes they regulate, how the regulatory elements act together, and answers to other questions have been unclear.
“Without the high-throughput system, identifying key regulatory elements is often extremely slow,” said corresponding author Yong Cheng, Ph.D., of the St. Jude Departments of Hematology and Computational Biology. Mitchell Weiss, M.D., Ph.D., Hematology chair, is co-corresponding author.
“For example, despite decades of research, fewer than half of regulatory elements and the associated genetic variants that account for fetal hemoglobin levels have been identified,” Cheng said.
Precision editing provides key details about regulation of gene expression
The new system combines bioinformatic prediction algorithms and an adenine base editing tool with tests to measure how base gene editing affects gene expression. Base editing works more precisely than conventional gene-editing tools such as CRISPR/Cas9, by changing a single letter in the four-letter DNA alphabet at high efficiency without creating larger insertions or deletions.
Researchers used the base editor ABEmax to make 10,156 specific edits in 307 regulatory elements that were predicted to affect fetal hemoglobin expression. The expression can modify the severity of hemoglobin disorders such as sickle cell disease. The edits changed the DNA bases adenine and thymine to guanine and cytosine. The study focused on regulatory elements in the genes BCL11A, MYB-HBS1L, KLF1 and beta-like globin genes.
Using this approach, the scientists validated the few known regulatory elements of fetal hemoglobin expression and identified many new ones.
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New research published in Experimental Physiology highlights the possible long term health impacts of COVID-19 on young, relatively healthy adults who were not hospitalized and who only had minor symptoms due to the virus.
Increased stiffness of arteries in particular was found in young adults, which may impact heart health, and can also be important for other populations who may have had severe cases of the virus. This means that young, healthy adults with mild COVID-19 symptoms may increase their risk of cardiovascular complications which may continue for some time after COVID-19 infection.
While SARS-CoV-2, the virus known for causing the COIVD-19 pandemic, is mainly characterized by respiratory symptoms, other studies have recently shown changes to blood vessel function among young adults 3-4 weeks after being infected with SARS-CoV-2 (Ratchford et al., 2021).
This has also been observed months after infection in older adults as well (Riou et al. J Clin Med. 2021).
The research team at Appalachian State University found that the virus may have detrimental effects to arteries throughout the body, including in the carotid artery which supplies the brain with blood.
This draws comparisons between SARS-CoV-2 and other acute bacterial and viral infections which alter arterial stiffness such as rheumatic fever, Kawasaki disease, pneumonia, H. Pylori, and lupus, all of which may persist long after symptoms have resolved.

The origins of a pretty smile have long been sought in the fearsome jaws of living sharks which have been considered living fossils reflecting the ancestral condition for vertebrate tooth development and inference of its evolution. However, this view ignores real fossils which more accurately reflect the nature of ancient ancestors.
New research led by the University of Bristol and the Naturalis Biodiversity Center published in Nature Ecology and Evolution reveals that the dentitions of living shark relatives are entirely unrepresentative of the last shared ancestor of jawed vertebrates.
The study reveals that while teeth evolved once, complex dentitions have been gained and lost many times in evolutionary history and tooth replacement in living sharks is not the best model in the search for therapeutic solutions to human dental pathologies.
Lead author Martin Rücklin from Naturalis Biodiversity Center in Leiden, The Netherlands said: “We used high energy x-rays at the TOMCAT beamline of the Swiss Light Source at the Paul Scherrer Institut in Switzerland, to study tooth and jaw structure and development among shark ancestors. These ischnacanthid acanthodians possessed marginal dentitions composed of multiple, successional tooth rows, that are quite unlike the tooth whorls that occur in front of the jaw in acanthodians and across the jaws of crown-chondrichthyans.”
Co-author Professor Philip Donoghue from the University of Bristol’s School of Earth Sciences said: “Dentitions of vertebrates are characterized by an organised arrangement to enable occlusion and efficient feeding over the lifetime of an animal. This organisation and pattering of teeth is thought to originate in a universal development mechanism, the dental lamina, seen in sharks. The condition we see in the successional tooth rows cannot be explained by this mechanism.”
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