Probiotic Supplement Use Associated With Fewer Respiratory Symptoms in Overweight and Older People

Findings provide further evidence of relationship between the gut and lungs.

Daily probiotic use was associated with fewer upper respiratory symptoms in overweight and older people, according to a study that suggests a potential role for probiotics in preventing respiratory infections. The study was selected for presentation at Digestive Disease Week® (DDW) 2021.

“This is not necessarily the most intuitive idea, that putting bacteria into your gut might reduce your risk of respiratory infection,” said Benjamin Mullish, MD, a lead researcher on the study and clinical lecturer in the Division of Digestive Diseases, Imperial College London, England, “but it’s further evidence that the gut microbiome has a complex relationship with our various organ systems. It doesn’t just affect how our gut works or how our liver works, it affects aspects of how our whole body works.”

Researchers re-analyzed detailed daily diaries of 220 patients who participated in an earlier double-blind placebo-controlled study on probiotics and weight loss. Reviewing the entries for common symptoms of upper respiratory infection, including cough, sore throat, and wheezing, researchers found that participants who took probiotics during the six-month study had a 27 percent lower overall incidence of upper respiratory tract symptoms compared to the placebo group. The effect was largest among participants who were aged 45 years or older, as well as those with obesity.

People with obesity are at higher risk for respiratory infections. Previous research has shown that probiotics reduce upper respiratory infections in healthy adults and children, but little data exists on this vulnerable population of older, overweight and people with obesity.

“These findings add to growing interest in the gut-lung axis — how the gut and the lungs communicate with each other,” Dr. Mullish said. “It’s not just the gut sending out signals that affect how the lungs work. It works in both directions. It adds to the story that changes in the gut microbiome can affect large aspects of our health.”

The researchers did not measure immune response, only respiratory symptoms. Future randomized clinical trials could help identify the mechanisms related to the reduction in respiratory symptoms and explore the possible impact of probiotics on the immune system, Dr. Mullish said.

DDW Presentation Details

Dr. Mullish will present data from the study, “Daily probiotic use is associated with a reduced rate of upper respiratory tract symptoms in overweight and obese people,” abstract 739, on Sunday, May 23, at 1:16 p.m. EDT.

Digestive Disease Week® (DDW) is the largest international gathering of physicians, researchers and academics in the fields of gastroenterology, hepatology, endoscopy and gastrointestinal surgery. Jointly sponsored by the American Association for the Study of Liver Diseases (AASLD), the American Gastroenterological Association (AGA) Institute, the American Society for Gastrointestinal Endoscopy (ASGE) and the Society for Surgery of the Alimentary Tract (SSAT), DDW is a fully virtual meeting from May 21-23, 2021. The meeting showcases more than 2,000 abstracts and hundreds of lectures on the latest advances in GI research, medicine and technology.

Hidden Processes Revealed at Work in the Hearts of Massive Stars

A simulation of a 3-solar-mass star shows the central, convective core and the waves it generates in the rest of the star’s interior. Credit: Philipp Edelmann

Astronomers commonly refer to massive stars as the chemical factories of the Universe. They generally end their lives in spectacular supernovae, events that forge many of the elements on the periodic table. How elemental nuclei mix within these enormous stars has a major impact on our understanding of their evolution prior to their explosion. It also represents the largest uncertainty for scientists studying their structure and evolution.

A team of astronomers led by May Gade Pedersen, a postdoctoral scholar at UC Santa Barbara’s Kavli Institute for Theoretical Physics, have now measured the internal mixing within an ensemble of these stars using observations of waves from their deep interiors. While scientists have used this technique before, this paper marks the first time this has been accomplished for such a large group of stars at once. The results, published in Nature Astronomy, show that the internal mixing is very diverse, with no clear dependence on a star’s mass or age.

Stars spend the majority of their lives fusing hydrogen into helium deep in their cores. However, the fusion in particularly massive stars is so concentrated at the center that it leads to a turbulent convective core similar to a pot of boiling water. Convection, along with other processes like rotation, effectively removes helium ash from the core and replaces it with hydrogen from the envelope. This enables the stars to live much longer than otherwise predicted.

Astronomers believe this mixing arises from various physical phenomena, like internal rotation and internal seismic waves in the plasma excited by the convecting core. However, the theory has remained largely unconstrained by observations as it occurs so deep within the star. That said, there is an indirect method of peering into stars: asteroseismology, the study and interpretation of stellar oscillations. The technique has parallels to how seismologists use earthquakes to probe the interior of the Earth.

Mixing transports fused material away and replaces it with more hydrogen fuel from the star’s outer layers. Credit: May Gade Pedersen

“The study of stellar oscillations challenges our understanding of stellar structure and evolution,” Pedersen said. “They allow us to directly probe the stellar interiors and make comparisons to the predictions from our stellar models.”

Pedersen and her collaborators from KU Leuven, the University of Hasselt, and the University of Newcastle have been able to derive the internal mixing for an ensemble of such stars using asteroseismology. This is the first time such a feat has been achieved, and was possible thanks only to a new sample of 26 slowly pulsating B-type stars with identified stellar oscillations from NASA’s Kepler mission.

Slowly pulsating B-type stars are between three and eight times more massive than the Sun. They expand and contract on time scales of the order of 12 hours to 5 days, and can change in brightness by up to 5%. Their oscillation modes are particularly sensitive to the conditions near the core, Pedersen explained.

“The internal mixing inside stars has now been measured observationally and turns out to be diverse in our sample, with some stars having almost no mixing while others reveal levels a million times higher,” Pedersen said. The diversity turns out to be unrelated to the mass or age of the star. Rather, it’s primarily influenced by the internal rotation, though that is not the only factor at play.

“These asteroseismic results finally allow astronomers to improve the theory of internal mixing of massive stars, which has so far remained uncalibrated by observations coming straight from their deep interiors,” she added.

The precision at which astronomers can measure stellar oscillations depends directly on how long a star is observed. Increasing the time from one night to one year results in a thousand-fold increase in the measured precision of oscillation frequencies.

“May and her collaborators have really shown the value of asteroseismic observations as probes of the deep interiors of stars in a new and profound way,” said KITP Director Lars Bildsten, the Gluck Professor of Theoretical Physics. “I am excited to see what she finds next.”

The best data currently available for this comes from the Kepler space mission, which observed the same patch of the sky for four continuous years. The slowly pulsating B-type stars were the highest mass pulsating stars that the telescope observed. While most of these are slightly too small to go supernova, they do share the same internal structure as the more massive stellar chemical factories. Pedersen hopes insights gleaned from studying the B type stars will shed light on the inner workings of their higher mass, O type counterparts.

She plans to use data from NASA’s Transiting Exoplanet Survey Satellite (TESS) to study groups of oscillating high-mass stars in OB associations. These groups comprise 10 to more than 100 massive stars between 3 and 120 solar masses. Stars in OB associations are born from the same molecular cloud and share similar ages, she explained. The large sample of stars, and constraint from their common ages, provides exciting new opportunities to study the internal mixing properties of high-mass stars.

In addition to unveiling the processes hidden within stellar interiors, research on stellar oscillations can also provide information on other properties of the stars.

“The stellar oscillations not only allow us to study the internal mixing and rotation of the stars, but also determine other stellar properties such as mass and age,” Pedersen explained. “While these are both two of the most fundamental stellar parameters, they are also some of the most difficult to measure.”

Reference: “Internal mixing of rotating stars inferred from dipole gravity modes” by May G. Pedersen, Conny Aerts, Péter I. Pápics, Mathias Michielsen, Sarah Gebruers, Tamara M. Rogers, Geert Molenberghs, Siemen Burssens, Stefano Garcia and Dominic M. Bowman, 10 May 2021, Nature Astronomy.
DOI: 10.1038/s41550-021-01351-x

Revolutionary Eco-Friendly Plastic: The Future Looks Bright for Infinitely Recyclable Plastic

Only about 2% of plastics are fully recycled currently. PDK plastics could solve the single-use crisis.

A new environmental and technological analysis suggests that a revolutionary eco-friendly plastic is almost ready to hit the shelves.

Plastics are a part of nearly every product we use on a daily basis. The average person in the U.S. generates about 100 kg of plastic waste per year, most of which goes straight to a landfill. A team led by Corinne Scown, Brett Helms, Jay Keasling, and Kristin Persson at Lawrence Berkeley National Laboratory (Berkeley Lab) set out to change that.

Less than two years ago, Helms announced the invention of a new plastic that could tackle the waste crisis head on. Called poly(diketoenamine), or PDK, the material has all the convenient properties of traditional plastics while avoiding the environmental pitfalls, because unlike traditional plastics, PDKs can be recycled indefinitely with no loss in quality.

Now, the team has released a study that shows what can be accomplished if manufacturers began using PDKs on a large scale. The bottom line? PDK-based plastic could quickly become commercially competitive with conventional plastics, and the products will get less expensive and more sustainable as time goes on.

“Plastics were never designed to be recycled. The need to do so was recognized long afterward,” explained Nemi Vora, first author on the report and a former postdoctoral fellow who worked with senior author Corinne Scown. “But driving sustainability is the heart of this project. PDKs were designed to be recycled from the get-go, and since the beginning, the team has been working to refine the production and recycling processes for PDK so that the material could be inexpensive and easy enough to be deployed at commercial scales in anything from packaging to cars.”

The study presents a simulation for a 20,000-metric-ton-per-year facility that puts out new PDKs and takes in used PDK waste for recycling. The authors calculated the chemical inputs and technology needed, as well as the costs and greenhouse gas emissions, then compared their findings to the equivalent figures for production of conventional plastics.

“These days, there is a huge push for adopting circular economy practices in the industry. Everyone is trying to recycle whatever they’re putting out in the market,” said Vora. “We started talking to industry about deploying 100% infinitely recycled plastics and have received a lot of interest.”

“The questions are how much it will cost, what the impact on energy use and emissions will be, and how to get there from where we are today,” added Helms, a staff scientist at Berkeley Lab’s Molecular Foundry. “The next phase of our collaboration is to answer these questions.”

Checking the boxes of cheap and easy

To date, more than 8.3 billion metric tons of plastic material have been produced, and the vast majority of this has ended up in landfills or waste incineration plants. A small proportion of plastics are sent to be recycled “mechanically,” meaning they are melted down and then re-shaped into new products. However, this technique has limited benefit. Plastic resin itself is made of many identical molecules (called monomers) bound together into long chains (called polymers). Yet to give plastic its many textures, colors, and capabilities, additives like pigments, heat stabilizers, and flame retardants are added to the resin. When many plastics are melted down together, the polymers become mixed with a slew of potentially incompatible additives, resulting in a new material with much lower quality than newly produced virgin resin from raw materials. As such, less than 10% of plastic is mechanically recycled more than once, and recycled plastic usually also contains virgin resin to make up for the dip in quality.

A GIF showing how PDK plastic readily breaks down when put in an acidic solution. The acid helps to break the bonds between the monomers and separate them from the chemical additives that give plastic its look and feel. Credit: Peter Christensen/Berkeley Lab

PDK plastics sidestep this problem entirely – the resin polymers are engineered to easily break down into individual monomers when mixed with an acid. The monomers can then be separated from any additives and gathered to make new plastics without any loss of quality. The team’s earlier research shows that this “chemical recycling” process is light on energy and carbon dioxide emissions, and it can be repeated indefinitely, creating a completely circular material lifecycle where there is currently a one-way ticket to waste.

Yet despite these incredible properties, to truly beat plastics at their own game, PDKs also need to be convenient. Recycling traditional petroleum-based plastic might be hard, but making new plastic is very easy.

“We’re talking about materials that are basically not recycled,” said Scown. “So, in terms of appealing to manufacturers, PDKs aren’t competing with recycled plastic – they have to compete with virgin resin. And we were really pleased to see how cheap and how efficient it will be to recycle the material.”

Scown, who is a staff scientist in Berkeley Lab’s Energy Technologies and Biosciences Areas, specializes in modeling future environmental and financial impacts of emerging technologies. Scown and her team have been working on the PDK project since the outset, helping Helms’ group of chemists and fabrication scientists to choose the raw materials, solvents, equipment, and techniques that will lead to the most affordable and eco-friendly product.

“We’re taking early stage technology and designing what it would look like at commercial-scale operations” using different inputs and technology, she said. This unique, collaborative modeling process allows Berkeley Lab scientists to identify potential scale-up challenges and make process improvements without costly cycles of trial and error.

The team’s report, published in Science Advances, models a commercial-scale PDK production and recycling pipeline based on the plastic’s current state of development. “And the main takeaways were that, once you’ve produced the PDK initially and you’ve got it in the system, the cost and the greenhouse gas emissions associated with continuing to recycle it back to monomers and make new products could be lower than, or at least on par with, many conventional polymers,” said Scown.

Planning to launch

Thanks to optimization from process modeling, recycled PDKs are already drawing interest from companies needing to source plastic. Always looking to the future, Helms and his colleagues have been conducting market research and meeting with people from industry since the project’s early days. Their legwork shows that the best initial application for PDKs are markets where the manufacturer will receive their product back at the end of its lifespan, such as the automobile industry (through trade-ins and take-backs) and consumer electronics (through e-waste programs). These companies will then be able to reap the benefits of 100% recyclable PDKs in their product: sustainable branding and long-term savings.

Workers sorting plastic waste.

“With PDKs, now people in industry have a choice,” said Helms. “We’re bringing in partners who are building circularity into their product lines and manufacturing capabilities, and giving them an option that is in line with future best practices.”

Added Scown: “We know there’s interest at that level. Some countries have plans to charge hefty fees on plastic products that rely on non-recycled material. That shift will provide a strong financial incentive to move away from utilizing virgin resins and should drive a lot of demand for recycled plastics.”

After infiltrating the market for durable products like cars and electronics, the team hopes to expand PDKs into shorter-lived, single-use goods such as packaging.

A full-circle future

As they forge plans for a commercial launch, the scientists are also continuing their techno-economic collaboration on the PDK production process. Although the cost of recycled PDK is already projected to be competitively low, the scientists are working on additional refinements to lower the cost of virgin PDK, so that companies are not deterred by the initial investment price.

And true to form, the scientists are working two steps ahead at the same time. Scown, who is also vice president for Life-cycle, Economics & Agronomy at the Joint BioEnergy Institute (JBEI), and Helms are collaborating with Jay Keasling, a leading synthetic biologist at Berkeley Lab and UC Berkeley and CEO of JBEI, to design a process for producing PDK polymers using microbe-made precursor ingredients. The process currently uses industrial chemicals, but was initially designed with Keasling’s microbes in mind, thanks to a serendipitous cross-disciplinary seminar.

“Shortly before we started the PDK project, I was in a seminar where Jay was describing all the molecules that they could make at JBEI with their engineered microbes,” said Helms. “And I got very excited because I saw that some of those molecules were things that we put in PDKs. Jay and I had a few chats, and we realized that nearly the entire polymer could be made using plant material fermented by engineered microbes.”

“In the future, we’re going to bring in that biological component, meaning that we can begin to understand the impacts of transitioning from conventional feedstocks to unique and possibly advantaged bio-based feedstocks that might be more sustainable long term on the basis of energy, carbon, or water intensity of production and recycling,” Helms continued.

“So, where we are now, this is the first step of many, and I think we have a really long runway in front of us, which is exciting.”

Reference: “Leveling the cost and carbon footprint of circular polymers that are chemically recycled to monomer” by Nemi Vora, Peter R. Christensen, Jérémy Demarteau, Nawa Raj Baral, Jay D. Keasling, Brett A. Helms and Corinne D. Scown, 9 April 2021, Science Advances.
DOI: 10.1126/sciadv.abf0187

The Molecular Foundry is a Department of Energy (DOE) Office of Science user facility that specializes in nanoscale science. JBEI is a Bioenergy Research Center funded by DOE’s Office of Science.

This work was supported by the DOE’s Bioenergy Technologies Office and Berkeley Lab’s Laboratory Directed Research and Development (LDRD) program.

The First Frost Is the Deepest – New Discovery May Help Us Grow Crops in Fluctuating Climate

Frost on Arabidopsis thaliana — new discovery may help us grow crops in fluctuating climate. Credit: John Innes Centre

The first frost of autumn may be grim for gardeners but the latest evidence reveals it is a profound event in the life of plants.

The discovery may affect how we grow crops in a fluctuating climate and help us better understand molecular mechanisms in animals and humans.

Much of our understanding of how plants register temperature at a molecular level has been gained from the study of vernalization — the exposure to an extended period of cold as a preparation for flowering in spring.

Experiments using the model plant Arabidopsis have shown how this prolonged period of cold lifts the brake on flowering, a gene called FLC. This biochemical brake also involves another molecule COOLAIR which is antisense to FLC. This means it lies on the other strand of DNA to FLC and it can bind to FLC and influence its activity.

But less is known about how natural temperature changes affect this process. How does COOLAIR facilitate the shutdown of FLC in nature?

To find out, researchers from the John Innes Centre used naturally occurring types of Arabidopsis grown in different climates.

They measured how much COOLAIR is turned on in three different field sites with varying winter conditions, one in Norwich, UK, one in south Sweden, and one in subarctic northern Sweden.

COOLAIR levels varied among different accessions and different locations. However, researchers spotted something that all the plants had in common — the first time the temperature dropped below freezing there was a peak in COOLAIR.

To confirm this boosting of COOLAIR after freezing they did experiments in temperature-controlled chambers which simulated the temperature changes seen in natural conditions.

They found COOLAIR expression levels rose within an hour of freezing and peaked about eight hours afterwards. There was a small reduction in FLC levels immediately after freezing too, reflecting the relationship between the two key molecular components.

Next, they found a mutant Arabidopsis which produces higher levels of COOLAIR all the time even when it is not cold, and low levels of FLC. When they edited the gene to switch off COOLAIR they found that FLC was no longer suppressed, providing further evidence of this elegant molecular mechanism.

Dr Yusheng Zhao, co-first author of the study said: “Our study shows a new aspect of temperature sensing in plants in natural field conditions. The first seasonal frost serves as an important indicator in autumn for winter arrival. The initial freezing dependent induction of COOLAIR appears to be an evolutionarily conserved feature in Arabidopsis and helps to explain how plants sense environmental signals to begin silencing of the major floral repressor FLC to align flowering with spring.”

The study offers insight into the plasticity in the molecular process of how plants sense temperatures which may help plants adapt to different climates.

Professor Dame Caroline Dean, corresponding author of the study explained: “From the plant’s point of view it gives you a tunable way of shutting off FLC. Any modulation of antisense will switch off sense and from an evolutionary perspective, depending on how efficiently or how fast this happens, and how many cells it happens in, you then have a way of dialing the brake up and down among cells.”

The findings will be helpful for understanding how plants and other organisms sense fluctuating environmental signals and could be translatable to improving crops at a time of climate change.

The discovery will also likely be widely relevant for environmental regulation of gene expression in many organisms because antisense transcription has been shown to alter transcription in yeast and human cells.

Reference: “Natural temperature fluctuations promote COOLAIR regulation of FLC” by Yusheng Zhao1, Pan Zhu1, Jo Hepworth, Rebecca Bloomer, Rea Laila Antoniou-Kourounioti, Jade Doughty, Amelie Heckmann, Congyao Xu, Hongchun Yang and Caroline Dean, 13 May 2021, Genes & Development.
DOI: 10.1101/gad.348362.121

Preventing the Next Pandemic: Scientists Say We Must Regulate Air Like Food and Water

Humans in the 21st century spend most of their time indoors, but the air we breathe inside buildings is not regulated to the same degree as the food we eat and the water we drink. A group of 39 researchers from 14 countries, including two from the University of Colorado Boulder, say that needs to change to reduce disease transmission and prevent the next pandemic.

In a Perspectives piece published in Science on May 14, 2021, they call for a “paradigm shift” in combating airborne pathogens such as SARS-CoV-2, the virus that causes COVID-19, demanding universal recognition that respiratory infections can be prevented by improving indoor ventilation systems.

“Air can contain viruses just as water and surfaces do,” said co-author Shelly Miller, professor of mechanical and environmental engineering. “We need to understand that it’s a problem and that we need to have, in our toolkit, approaches to mitigating risk and reducing the possible exposures that could happen from build-up of viruses in indoor air.”

The paper comes less than two weeks after the World Health Organization (WHO) changed its website to acknowledge that SARS-CoV-2 is spread predominantly through the air, and 10 months after the WHO acknowledged the potential for aerosol transmission and 239 scientists (including Miller and Jose-Luis Jimenez) signed an open letter to medical communities and governing bodies about the potential risk of airborne transmission. The researchers now call on the WHO and other governing bodies in this new article to extend its indoor air quality guidelines to include airborne pathogens and to recognize the need to control hazards of airborne transmission of respiratory infections.

A tangle of ducted air pipes are connected to a portable air unit being used to air condition a large hall. Credit: Martin Visser, Unsplash

Such a shift in ventilation standards should be similar in scale to the 19th century transformation that took place when cities started organizing clean water supplies and centralized sewage systems. But it would also correct a major scientific misperception that arose around the same time.

When people in London were dying of cholera in the 1850s, scientists assumed the disease was airborne. But British physician John Snow discovered that microorganisms in contaminated water were the reason. Similarly, Hungarian physician Ignaz Semmelweis showed that handwashing before delivering a baby greatly reduced postpartum infections. While these discoveries encountered great resistance in their time, scientists eventually agreed that in these cases, water and hands — not air — were the vector for disease.

Then in the early 20th century, American public health expert Charles Chapin erroneously attributed respiratory infections caught in close proximity to other people to large droplets produced by an infected person, which fall quickly to the ground. As a result, he stated that airborne transmission was almost impossible.

Yet in 1945, scientist William Wells published a paper in the predecessor to Science, lamenting that while we were investing in disinfecting water and keeping our food clean, we had done nothing for our indoor air, given the denial of airborne transmission. His research on measles and tuberculosis — caused by airborne pathogens — challenged this notion in the 20th century, but didn’t break it.

Now that the research on SARS-CoV-2 finally has brought to light that many respiratory diseases can be transmitted through the air, researchers argue that we must take action.

“Let’s now not waste time until the next pandemic,” said co-author Jose-Luis Jimenez, fellow in the Cooperative Institute of Research Sciences (CIRES) and professor of chemistry at CU Boulder. “We need a societal effort. When we design a building, we shouldn’t just put in the minimum amount of ventilation that’s possible, but instead we should keep ongoing respiratory diseases, such as the flu, and future pandemics in mind.”

The long-standing misunderstanding of the importance of airborne transmission of pathogens has left a large gap of information in how to best construct and manage building ventilation systems to mitigate the spread of disease — with the exception of some manufacturing, research and medical facilities. Instead, buildings have focused on temperature, odor control, energy use, and perceived air quality. So while there are safety guidelines for chemicals such as carbon monoxide, there are currently no guidelines, globally or in the U.S., that regulate or provide standards for mitigating bacteria or viruses in indoor air resulting from human activities.

“Air in buildings is shared air — it’s not a private good, it’s a public good. And we need to start treating it like that,” said Miller.

Lidia Morawska, lead author on the article and director of Queensland University of Technology’s International Laboratory for Air Quality and Health, said there needs to be a shift away from the perception that we cannot afford the cost of control. She notes that the global monthly cost from COVID-19 had been conservatively estimated as $1 trillion and the cost of influenza in the U.S. alone exceeded $11.2 billion annually.

While detailed economic analysis has yet to be done, estimates suggest necessary investments in building systems may be less than 1% of the construction cost of a typical building.

Ventilation systems should also be demand-controlled to adjust for different room occupancies, and differing activities and breathing rates, such as exercising in a gym versus sitting in a movie theatre, according to Morawska. For spaces that cannot improve ventilation to an appropriate level for the use of the space, she said air filtration and disinfection will be needed.

Because buildings consume over one-third of energy globally, much from heating or cooling outdoor air as it is brought indoors, it would be useful to design a “pandemic mode,” that would allow for buildings to only use more energy when necessary, said Jimenez.

The researchers also call for national comprehensive indoor air quality (IAQ) standards to be developed and enforced by all countries, and for this information to be available to the public.

For this to happen, however, many more than scientists will need to understand its importance.

“I think there is a certain amount of demand that needs to start coming from the consumer and from the person who works in these indoor spaces in order to push change,” said Miller.

Reference: 14 May 2021, Science.
DOI: 10.1126/science.abg2025

Accidental Release From a Lab or Zoonotic Spillover? Scientists Call for Investigation Into the Origins of COVID-19

Letter From Scientists: Investigate the Origins of COVID-19

More investigation is needed to determine the origin of the COVID-19 pandemic, say Jesse Bloom, Alina Chan, Ralph Baric, David Relman and colleagues in this Letter.

“Theories of accidental release from a lab and zoonotic spillover both remain viable,” they say. “Knowing how COVID-19 emerged is critical for informing global strategies to mitigate the risk of future outbreaks.”

The authors highlight a joint China-World Health Organization (WHO) report into the origins of SARS-CoV-2, some results of which were released in November 2020. “WHO Director-General Tedros Ghebreyesus commented that the report’s consideration of evidence supporting a laboratory accident was insufficient,” they note. “As scientists with relevant expertise, we agree with the WHO director-general, the United States and 13 other countries, and the European Union that greater clarity about the origins of this pandemic is necessary and feasible to achieve,” they say.

They call for an investigation that is “transparent, objective, data-driven, inclusive of broad expertise, subject to independent oversight, and responsibly managed.” In concluding their Letter, they write: “in this time of unfortunate anti-Asian sentiment in some countries, we note that at the beginning of the pandemic, it was Chinese doctors, scientists, journalists, and citizens who shared with the world crucial information about the spread of the virus — often at great personal cost. We should show the same determination in promoting a dispassionate science-based discourse on this difficult but important issue.”

Reference: “Investigate the origins of COVID-19” by J.D. Bloom at Fred Hutchinson Cancer Research Center in Seattle, WA; J.D. Bloom; A. Iwasaki; R. Medzhitov at Howard Hughes Medical Institute in Chevy Chase, MD; Y. Alina Chan; B.E. Deverman at Broad Institute of MIT and Harvard in Cambridge, MA; R.S. Baric at University of North Carolina at Chapel Hill in Chapel Hill, NC; P.J. Bjorkman at California Institute of Technology in Pasadena, CA; S. Cobey at University of Chicago in Chicago, IL; D.N. Fisman at University of Toronto in Toronto, ON, Canada; R. Gupta at Cambridge Institute of Therapeutic Immunology & Infectious Disease in Cambridge, UK; A. Iwasaki; R. Medzhitov at Yale University School of Medicine in New Haven, CT; M. Lipsitch at Harvard T. H. Chan School of Public Health in Boston, MA; R.A. Neher; E. van Nimwegen at University of Basel in Basel, Switzerland; R.A. Neher; E. van Nimwegen at Swiss Institute of Bioinformatics in Basel, Switzerland; R. Nielsen at University of California, Berkeley in Berkeley, CA; N. Patterson at Harvard University in Cambridge, MA; T. Stearns; D.A. Relman at Stanford University in Stanford, CA; M. Worobey at University of Arizona in Tucson, AZ; D.A. Relman at Stanford University School of Medicine in Stanford, CA.
DOI: 10.1126/science.abj0016

Evolutionary Biologists Just Discovered How Some Lizards Are Able to Breathe Underwater

Close-up of an Anolis lizard with a rebreathing bubble on its snout. Credit: Lindsey Swierk

A team of evolutionary biologists from the University of Toronto has shown that Anolis lizards, or anoles, are able to breathe underwater with the aid of a bubble clinging to their snouts.

Anoles are a diverse group of lizards found throughout the tropical Americas. Some anoles are stream specialists, and these semi-aquatic species frequently dive underwater to avoid predators, where they can remain submerged for as long as 18 minutes.

“We found that semi-aquatic anoles exhale air into a bubble that clings to their skin,” says Chris Boccia, a recent Master of Science graduate from the Faculty of Arts & Science’s Department of Ecology & Evolutionary Biology (EEB). Boccia is lead author of a paper describing the finding published this week in Current Biology.

“The lizards then re-inhale the air,” says Boccia, “a maneuver we’ve termed ‘rebreathing’ after the scuba-diving technology.”

The researchers measured the oxygen (O2) content of the air in the bubbles and found that it decreased over time, confirming that rebreathed air is involved in respiration.

Rebreathing likely evolved because the ability to stay submerged longer increases the lizard’s chances of eluding predators.

A submerged Anolis lizard with a rebreathing bubble on its snout. Credit: Lindsey Swierk

The authors studied six species of semi-aquatic anoles and found that all possessed the rebreathing trait, despite most species being distantly related. While rebreathing has been studied extensively in aquatic arthropods like water beetles, it was not expected in lizards because of physiological differences between arthropods and vertebrates.

“Rebreathing had never been considered as a potential natural mechanism for underwater respiration in vertebrates,” says Luke Mahler, an assistant professor in EEB and Boccia’s thesis supervisor. “But our work shows that this is possible and that anoles have deployed this strategy repeatedly in species that use aquatic habitats.”

Mahler and co-author Richard Glor, from the University of Kansas, first observed anoles rebreathing in Haiti in 2009 but were unable to carry out further observations or experiments. Another co-author, Lindsey Swierk, from Binghamton University, State University of New York, described the same behavior in a Costa Rican species in 2019. These early observations suggested that rebreathing was an adaptation for diving, but this idea had not been tested until now.

Boccia became interested in aquatic anoles after encountering one in Panama. He began his rebreathing investigations in Costa Rica in 2017 and continued the research in Colombia and Mexico.

As the authors point out, the rebreathing trait may have developed because anoles’ skin is hydrophobic — it repels water — a characteristic that likely evolved in anoles because it protects them from rain and parasites. Underwater, air bubbles cling to hydrophobic skin, and the ability to exploit these bubbles for breathing developed as a result.

While further work is required to understand how the process works in detail, Boccia, Mahler, and their co-authors suggest different ways in which rebreathing may function.

In its simplest form, the air bubble on a lizard’s snout likely acts like a scuba tank, providing a submerged animal with a supply of air in addition to the air in its lungs. This is what aquatic arthropods like water beetles do to extend the time they can remain submerged.

The researchers also suggest that the rebreathing process may facilitate using air found in a lizard’s nasal passages, mouth, and windpipe that would otherwise not be used by the lizard in breathing.

The bubble may also help rid waste carbon dioxide (CO2) from exhaled air through a process other researchers have already observed in aquatic arthropods. Those studies concluded that because CO2 is highly soluble in water and because the level of CO2 in the bubbles is higher than in the surrounding water, exhaled CO2 dissolves into the surrounding water rather than being rebreathed.

Finally, the authors speculate that the bubble may act as a gill and absorb oxygen from the water — again, something already observed in arthropods. Boccia and Mahler are planning further research to confirm if these rebreathing processes are occurring with anoles.

According to Mahler, “This work enriches our understanding of the creative and unexpected ways that organisms meet the challenges posed by their environments. That is valuable in its own right, but discoveries like this can also be valuable to humans as we seek solutions to our own challenging problems.”

“It’s too early to tell if lizard rebreathing will lead to any particular human innovations,” says Boccia, “But biomimicry of rebreathing may be an interesting proposition for several fields — including scuba-diving rebreathing technology, which motivated our naming of this phenomenon.”

Reference: “Repeated evolution of underwater rebreathing in diving Anolis lizards” by Christopher K. Boccia, Lindsey Swierk, Fernando P. Ayala-Varela, James Boccia, Isabela L. Borges, Camilo Andres Estupiñán, Alexandra M. Martin, Ramón E. Martínez-Grimaldo, Sebastian Ovalle, Shreeram Senthivasan, Ken S. Toyama, María del Rosario Castañeda, Andrés García, Richard E. Glor and D. Luke Mahler, 12 May 2021, Current Biology.
DOI: 10.1016/j.cub.2021.04.040

Mahler’s participation in the research was supported by an NSERC Discovery Grant and a Harvard University Ken Miyata Field Research Award. Boccia’s participation was supported by an NSERC CGS M Grant, a National Geographic Young Explorer Grant and a Sigma Xi Grant in Aid of Research.

How to Cloak an Object to Become Invisible to a Thermal Camera

Theoretical method can make objects invisible to a thermal camera, or mimic a different object.

Can you feel the heat? To a thermal camera, which measures infrared radiation, the heat that we can feel is visible, like the heat of a traveler in an airport with a fever or the cold of a leaky window or door in the winter.

In a paper published in Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, an international group of applied mathematicians and physicists, including Fernando Guevara Vasquez and Trent DeGiovanni from the University of Utah, report a theoretical way of mimicking thermal objects or making objects invisible to thermal measurements. And it doesn’t require a Romulan cloaking device or Harry Potter’s invisibility cloak. The research is funded by the National Science Foundation.

The method allows for fine-tuning of heat transfer even in situations where the temperature changes in time, the researchers say. One application could be to isolate a part that generates heat in a circuit (say, a power supply) to keep it from interfering with heat sensitive parts (say, a thermal camera). Another application could be in industrial processes that require accurate temperature control in both time and space, for example controlling the cooling of a material so that it crystallizes in a particular manner.

Watch a visualization of how the method cloaks a kite-shaped object here:

Left to right: 1. temperature of a plate subject to a point source firing at time t=0 (this could be e.g. a laser pulse). 2. temperature of the plate with a “kite” object present. As you can see the isotherms, or temperature contours, are deformed by the presence of the object and this can be used by an observer to detect and locate the kite. 3. the kite object is surrounded by our active cloak. Now the isotherms look exactly like the ones in the case where the object is not present, which hides the kite object. Credit: Fernando Guevara Vasquez/University of Utah

Or watch how it works for a Homer Simpson-shaped object here:

Left to right: 1. temperature of a plate subject to point source firing at time t=0 (this could be e.g. a laser pulse). 2. temperature of the plate with an object present. As you can see the isotherms, or temperature contours, are deformed by the presence of the object and this can be used by an observer to detect and locate the object. 3. The object is surrounded by our active cloak. Now the isotherms look exactly like the ones in the case where the object is not present, which hides the object. Credit: Fernando Guevara Vasquez

Cloaking or invisibility devices have long been elements of fictional stories, but in recent years scientists and engineers have explored how to bring science fiction into reality. One approach, using metamaterials, bends light in such a way as to render an object invisible.

Just as our eyes see objects if they emit or reflect light, a thermal camera can see an object if it emits or reflects infrared radiation. In mathematical terms, an object could become invisible to a thermal camera if heat sources placed around it could mimic heat transfer as if the object wasn’t there.

The novelty in the team’s approach is that they use heat pumps rather than specially crafted materials to hide the objects. A simple household example of a heat pump is a refrigerator: to cool groceries it pumps heat from the interior to the exterior. Using heat pumps is much more flexible than using carefully crafted materials, Guevara says. For example, the researchers can make one object or source appear as a completely different object or source. “So at least from the perspective of thermal measurements,” Guevara says, “they can make an apple appear as an orange.”

The researchers carried out the mathematical work needed to show that, with a ring of heat pumps around an object, it’s possible to thermally hide an object or mimic the heat signature of a different object.

The work remains theoretical, Guevara says, and the simulations assume a “probing” point source of heat that would reflect or bend around the object – the thermal equivalent of a flashlight in a dark room.

The temperature of that probing source must be known ahead of time, a drawback of the work. However the approach is within reach of current technology by using small heat pumps called Peltier elements that transport heat by passing an electrical current across a metal-metal junction. Peltier elements are already widely used in consumer and industrial applications.

The researchers envision their work could be used to accurately control the temperature of an object in space and time, which has applications in protecting electronic circuits. The results, the researchers say, could also be applied to accurate drug delivery, since the mathematics of heat transfer and diffusion are similar to those of the transfer and diffusion of medications. And, they add, the mathematics of how light behaves in diffuse media such as fog could lead to applications in visual cloaking as well.

Reference: “Active thermal cloaking and mimicking” by Maxence Cassier, Trent DeGiovanni, Sébastien Guenneau and Fernando Guevara Vasquez, 12 May 2021, Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences.
DOI: 10.1098/rspa.2020.0941

In addition to Guevara and DeGiovanni, Maxence Cassier, CNRS Researcher at the Fresnel Institute in Marseille, France and Sébastien Guenneau, CNRS researcher, UMI 2004 Abraham de Moivre-CNRS, Imperial College London, London, UK co-authored the study.

Prehistoric Fossilized Footprints Show Earliest Known Evidence of Mammals at the Seashore

A reconstruction of the brown-bear-sized mammals (Coryphodon) that made thousands of tracks in a 58-million-year-old, brackish water lagoon in what is now southern Wyoming. Credit: Anton Wroblewski

Today, the rocks of the Hanna Formation in south-central Wyoming are hundreds of miles away from the nearest ocean. But around 58 million years ago, Wyoming was oceanfront property, with large hippo-like mammals traipsing through nearshore lagoons.

In a study published in Scientific Reports, geologist Anton Wroblewski, an adjunct associate professor in the Department of Geology and Geophysics, and applied biodiversity scientist Bonnie Gulas-Wroblewski of the Texas A&M Natural Resources Institute, report the discovery of several sets of fossilized tracks, likely from the brown bear-sized Coryphodon, that represent the earliest known evidence of mammals gathering near an ocean.

“Trace fossils like footprints record interactions between organisms and their environments, providing information that body fossils alone cannot,” Wroblewski says. “In this case, trace fossils show that large- bodied mammals were regularly using marine environments only eight million years after non-avian dinosaurs went extinct.”

Anton Wroblewski points to an underprint made 58 million years ago by a heavy mammal (likely Coryphodon) walking on the deltaic deposits above. Underprints form when sediment is displaced downward by footsteps from heavy animals.” Credit: Anton Wroblewski

The tracks that the Drs. Wroblewski found in the Hanna Formation of Wyoming include underprints, impressions in soft sediment made when heavy animals walk on overlying sediment layers, as well as prints pressed into the surfaces of ancient tidal flats. Now preserved in sandstone, the tracks are more than half a mile (one kilometer) long and were made by two different animals, one with four toes and one with five. The five-toed tracks are consistent with Coryphodon, a semi-aquatic mammal similar to a hippopotamus. The owner of the four-toed tracks remains a mystery.

Section of the 58-million-year-old tracksite demonstrating near-vertical tilting of the originally horizontal bedding with three separate trackways made by five-toed mammals walking in parallel. Credit: Anton Wroblewski

“Paleontologists have been working in this area for thirty years, but they’ve been looking for bones, leaf fossils, and pollen, so they didn’t notice footprints or trackways,” Wroblewski says. He first saw the tracks in September 2019. “When I found them, it was late afternoon and the setting sun hit them at just the right angle to make them visible on the tilted slabs of sandstone. At first, I couldn’t believe what I was seeing; I had walked by this outcrop for years without noticing them. Once I saw the first few, I followed out the ridge of sandstone and realized they were part of a much larger, more extensive trackway.”

Fossilized plants and pollen helped the researchers determine the age of the tracks to be around 58 million years old, during the Paleocene epoch. Before this finding, the earliest known evidence of mammals interacting with marine environments came from the Eocene epoch, around 9.4 million years later. Wroblewski says that the Hanna Formation tracks are the first Paleocene mammal tracks found in the USA and only the fourth in the world, with two sets of tracks previously found in Canada and one in Svalbard, Norway. It’s also the largest accumulation of Paleocene mammal tracks in the world in both aerial extent and the absolute number of tracks, he says. With at least two species leaving the tracks, it’s also the most taxonomically diverse.

Today’s large mammals congregate near marine environments for a variety of reasons, including protection from predators and biting insects, foraging for unique foods, and access to salt sources, which may have been limited in the tropical forests of North America during the Paleocene. The researchers say ancient mammals may have had similar reasons for seeking out a day at the beach.

The research shows, Wroblewski says, that hypotheses of behavior and evolution based on isotopic, molecular and body fossil data can be empirically tested using trace fossils. “No other line of evidence directly records behaviors of extinct organisms preserved in their preferred habitats,” he says. “There’s still a lot of important information out there in the rocks, waiting for somebody to spot it when the lighting is just right!”

Reference: 13 May 2021, Scientific Reports.
DOI: 10.1038/s41598-021-88412-3

Supercomputer Simulations Reveal How Dominant COVID-19 Strain Binds to Host, Succumbs to Antibodies

Supercomputer simulations at Los Alamos National Laboratory demonstrated that the G form of SARS-CoV-2, the dominant strain of the virus causing COVID-19, mutated to a conformation that allows it to more easily attach to host receptors, while also being more susceptible to antibodies than the original D form. Credit: Los Alamos National Laboratory

Dominant G-form Spike protein ‘puts its head up’ more frequently to latch on to receptors, but that makes it more vulnerable to neutralization.

Large-scale supercomputer simulations at the atomic level show that the dominant G form variant of the COVID-19-causing virus is more infectious partly because of its greater ability to readily bind to its target host receptor in the body, compared to other variants. These research results from a Los Alamos National Laboratory–led team illuminate the mechanism of both infection by the G form and antibody resistance against it, which could help in future vaccine development.

“We found that the interactions among the basic building blocks of the Spike protein become more symmetrical in the G form, and that gives it more opportunities to bind to the receptors in the host — in us,” said Gnana Gnanakaran, corresponding author of the paper published recently in Science Advances. “But at the same time, that means antibodies can more easily neutralize it. In essence, the variant puts its head up to bind to the receptor, which gives antibodies the chance to attack it.”

Researchers knew that the variant, also known as D614G, was more infectious and could be neutralized by antibodies, but they didn’t know how. Simulating more than a million individual atoms and requiring about 24 million CPU hours of supercomputer time, the new work provides molecular-level detail about the behavior of this variant’s Spike.

Current vaccines for SARS-CoV-2, the virus that causes COVID-19, are based on the original D614 form of the virus. This new understanding of the G variant — the most extensive supercomputer simulations of the G form at the atomic level — could mean it offers a backbone for future vaccines.

The team discovered the D614G variant in early 2020, as the COVID-19 pandemic caused by the SARS-CoV-2 virus was ramping up. These findings were published in Cell. Scientists had observed a mutation in the Spike protein. (In all variants, it is the Spike protein that gives the virus its characteristic corona.) This D614G mutation, named for the amino acid at position 614 on the SARS-CoV-2 genome that underwent a substitution from aspartic acid, prevailed globally within a matter of weeks.

The Spike proteins bind to a specific receptor found in many of our cells through the Spike’s receptor binding domain, ultimately leading to infection. That binding requires the receptor binding domain to transition structurally from a closed conformation, which cannot bind, to an open conformation, which can.

The simulations in this new research demonstrate that interactions among the building blocks of the Spike are more symmetrical in the new G-form variant than those in the original D-form strain. That symmetry leads to more viral Spikes in the open conformation, so it can more readily infect a person.

A team of postdoctoral fellows from Los Alamos — Rachael A. Mansbach (now assistant professor of Physics at Concordia University), Srirupa Chakraborty, and Kien Nguyen — led the study by running multiple microsecond-scale simulations of the two variants in both conformations of the receptor binding domain to illuminate how the Spike protein interacts with both the host receptor and with the neutralizing antibodies that can help protect the host from infection. The members of the research team also included Bette Korber of Los Alamos National Laboratory, and David C. Montefiori, of Duke Human Vaccine Institute.

The team thanks Paul Weber, head of Institutional Computing at Los Alamos, for providing access to the supercomputers at the Laboratory for this research.

Reference: “The SARS-CoV-2 Spike variant D614G favors an open conformational state” by Rachael A. Mansbach, Srirupa Chakraborty, Kien Nguyen, David C. Montefiori, Bette Korber, S. Gnanakaran, 16 April 2021, Science Advances. 
DOI: 10.1126/sciadv.abf3671

Funding: The project was supported by Los Alamos Laboratory Directed Research and Development project 20200706ER, Director’s Postdoctoral fellowship, and the Center of Nonlinear Studies Postdoctoral Program at Los Alamos.

African Forest Elephants Are Now Critically Endangered – Here’s How to Count Them

A team of scientists compared methodologies to count African forest elephants (Loxodonta cyclotis), which were recently acknowledged by IUCN as a separate, Critically Endangered species from African savannah elephants. Credit: WCS Gabon

Study compared different methodologies using dung, DNA analysis, and camera traps.

A team of scientists led by the Wildlife Conservation Society (WCS) and working closely with experts from the Agence Nationale des Parcs Nationaux du Gabon (ANPN) compared methodologies to count African forest elephants (Loxodonta cyclotis), which were recently acknowledged by IUCN as a separate, Critically Endangered species from African savannah elephants. The study is part of a larger initiative in partnership with Vulcan Inc. to provide the first nationwide census in Gabon for more than 30 years. The results of the census are expected later this year.

Contrary to savannah elephants (Loxodonta africana) which can be counted directly, usually through aerial survey, accurately censusing elusive forest elephants is more challenging and refinements of methods were needed. Publishing a new survey method to counting forest elephants in the journal Global Ecology and Conservation, the team compared traditional methodologies to count elephant dung piles along line transects, with spatial capture-recapture (SCR) techniques using both camera traps and DNA dung analysis. SCR estimates populations by measuring how many times and in what location individual animals are recounted.

Said the study’s lead author, Alice Laguardia of WCS’s Gabon Program: “The more accurately we can count forest elephants, the more we can measure whether conservation efforts are successful.  We are hopeful that the results of this study will help governments and conservation partners protect this Critically Endangered species throughout its range.”

Researchers assessed the performance of the methodologies to three relatively large forest elephant populations in Gabon. They found that the SCR method that used DNA sampling of dung was comparable in accuracy to the line transect method but less expensive on larger scales.

Stephanie Bourgeois, coauthor and geneticist at ANPN, said: “Testing of this new DNA approach has been made possible by the recent development of novel genetics techniques by ANPN and the creation of a new genetics lab in Gabon enabling to perform all DNA analyses in-country.”

SCR Camera trap surveys were more precise on smaller scales but more expensive. The authors recommend that the use of both SCR methods, and their development, continue. They say that future findings and improvements should be compiled across studies to ensure their robust evolution as an option for monitoring the African forest elephant across its range and inform strategies and action for its conservation.

Forest elephants have been decimated by ivory poachers in recent years. A WCS-led census released in 2014 documented a 65 percent decline in forest elephant numbers between 2002 and 2013. Through this new study, researchers will gain a better understanding of how many forest elephants remain and where they reside. Efforts have been focused on Gabon as it is thought to harbor more than 50 percent of the remaining forest elephant population, despite accounting for less than 15 percent of the species’ range, making Gabon the most important country for forest elephant conservation. 

“As long as ivory is a precious commodity, elephants will be at risk,” said Lee White, the Gabonese Minister of Water, Forests, the Seas, the Environment, charged with Climate Change & Land Use Planning. “In Africa there is a clear link between environmental governance, peace, and security. Countries that have lost their elephant populations have all too often descended into civil strife. Through the results of this study we hope to obtain a clear picture of the trend of poaching and elephant populations in all of Gabon.”

“Vulcan recognizes the significant role of accurate population data for conservation management and policy decisions,” said Ted Schmitt, director, conservation at Vulcan Inc. “By providing timely census data, we can fill critical knowledge gaps and enable prioritization of conservation resources. We are pleased to be part of this effort with Wildlife Conservation Society and the government of Gabon to help preserve this important species.” 

Reference: “Assessing the feasibility of density estimation methodologies for African forest elephant at large spatial scales” by A. Laguardia, K. S. Gobush, S. Bourgeois, S. Strindberg, G. Abitsi, F. Ebouta, J. M. Fay, A. M. Gopalaswamy, F. Maisels, R. Ogden, L. J. T. White and E. J. Stokes, 26 March 2021, Global Ecology and Conservation.
DOI: 10.1016/j.gecco.2021.e01550

Funding for this critical work was provided by Vulcan Inc., a Seattle company founded by the late philanthropist Paul G. Allen and his sister Jody Allen, who currently serves as chair.

Solving The Mystery of the Pointy Droplets

A certain type of oil droplets changes shape when cooled and shrunk: from spherical through icosahedral to flat hexagonal. Two competing theories couldn’t fully explain this, but now, a Physical Review Letter by Ireth García-Aguilar and Luca Giomi solves the mystery.

It was an accidental discovery. Bulgarian researchers at Sofia University were studying small oily droplets of alkanes in water, stabilized with soap-like surfactant-molecules. “These are similar to the emulsion droplets in mayonnaise,” says Luca Giomi, “and in addition, they are enclosed in a frozen monolayer of alkane molecules and surfactants.”

When the Bulgarians were playing around with them, they realized that something special was going on. When the temperature was lowered, the droplets shifted from ordinary spherical shapes to odd, crystal-like icosahedral shapes. At even lower temperatures, they morphed into four-sided rhombuses or hexagons, with growing tentacles at the corners.

Around the same time, another group at Bar-Ilan University in Israel led by Eli Sloutskin, a coauthor of this letter, made similar observations and further realized that small droplets were more prone to change their shape compared to large droplets.

Exotic

“This is inspiring, it’s very exotic and something you wouldn’t expect,” says Giomi. Normally, large elastic sheets are floppier and more prone to bending than small sheets. “One can verify this by holding a sheet of paper on one side: an A4 sheet will immediately bend under its own weight, but a smaller sheet, such a post stamp, will remain straight. The larger the sheet, the higher the torque it experiences, the easier it bends.”

The group at Sofia University itself advanced a theory in which a special thin layer below the surfactants layer causes the edges, “but later, detailed microscopy images by Sloutskin’s lab, didn’t see such a layer,” says Giomi.

In order to explain the shape transformations as well as the anomalous size dependence, Leiden physicists had to include in their model four different ingredients: surface tension, gravity, defects, and spontaneous curvature. The latter is an effect of the shape of molecules that form the solid layer. When long molecules are stacked like matches in a box, the interface is flat, but when one of the molecules’ ends is fatter than the other, the resulting membrane may have a preferred curvature. 

Weird tentacles

While defects and gravity tend to bend the droplets, surface tension tends to restore the spherical shape. But, in the presence of spontaneous curvature, this effect becomes weaker as droplets become smaller, thus rendering small droplets prone to faceting. This explains the mysterious behavior, the researchers write in a paper in Physical Review Letters. 

One thing remains to be explained, however: the weird tentacles that develop at the lowest temperatures. “But we do have ideas,” says Giomi.

This type research is foundational and curiosity-driven, he adds. However, the behavior of living cells is always an inspiration. “Biological cells have an extraordinary capacity of changing their shapes with different circumstances.”

One of Giomi’s research topics is how cancer cells manage to split off their main tumor and migrate within the body to form deadly metastases. Giomi: “Cancer cells have to undergo dramatic shape changes in order to do so.” Understanding how simple micron-sized objects can autonomously adjust their shape may be critical to deciphering these processes.

Reference: “Faceting and Flattening of Emulsion Droplets: A Mechanical Model” by Ireth García-Aguilar, Piermarco Fonda, Eli Sloutskin, and Luca Giomi, 21 January 2021, Physical Review Letters.
DOI: 10.1103/PhysRevLett.126.038001

Signs of a Puzzling State of Matter Discovered in a Superconductor

Scientists at SLAC National Accelerator Laboratory used an improved X-ray technique to explore exotic states of matter in an unconventional superconductor that conducts electricity with 100% efficiency at relatively high temperatures. They glimpsed the signature of a state known as pair density waves (PDW), and confirmed that it intertwines with another phase known as charge density wave (CDW) stripes – wavelike patterns of higher and lower electron density in the material. CDWs, in turn, are created when spin density waves (SDWs) emerge and intertwine. Credit: Jun-Sik Lee/SLAC National Accelerator Laboratory

Known as “pair-density waves,” it may be key to understanding how superconductivity can exist at relatively high temperatures.

Unconventional superconductors contain a number of exotic phases of matter that are thought to play a role, for better or worse, in their ability to conduct electricity with 100% efficiency at much higher temperatures than scientists had thought possible – although still far short of the temperatures that would allow their wide deployment in perfectly efficient power lines, maglev trains and so on.

Now scientists at the Department of Energy’s SLAC National Accelerator Laboratory have glimpsed the signature of one of those phases, known as pair-density waves or PDW, and confirmed that it’s intertwined with another phase known as charge density wave (CDW) stripes – wavelike patterns of higher and lower electron density in the material.

Observing and understanding PDW and its correlations with other phases may be essential for understanding how superconductivity emerges in these materials, allowing electrons to pair up and travel with no resistance, said Jun-Sik Lee, a SLAC staff scientist who led the research at the lab’s Stanford Synchrotron Radiation Lightsource (SSRL).

Even indirect evidence of the PDW phase intertwined with charge stripes, he said, is an important step on the long road toward understanding the mechanism behind unconventional superconductivity, which has eluded scientists over more than 30 years of research.

Lee added that the method his team used to make this observation, which involved dramatically increasing the sensitivity of a standard X-ray technique known as resonant soft X-ray scattering (RSXS) so it could see the extremely faint signals given off by these phenomena, has potential for directly sighting both the PDW signature and its correlations with other phases in future experiments. That’s what they plan to work on next.

The scientists described their findings in an article published in Physical Review Letters.

Untangling superconductor secrets

The existence of the PDW phase in high-temperature superconductors was proposed more than a decade ago and it’s become an exciting area of research, with theorists developing models to explain how it works and experimentalists searching for it in a variety of materials.

In this study, the researchers went looking for it in a copper oxide, or cuprate, material known as LSCFO for the elements it contains ­– lanthanum, strontium, copper, iron and oxygen. It’s thought to host two other phases that may intertwine with PDW: charge density wave stripes and spin density wave stripes.

The nature and behavior of charge and spin stripes have been explored in a number of studies, but there had been only a few indirect glimpses of PDW – much like identifying an animal from its tracks – and none made with X-ray scattering techniques. Because X-ray scattering reveals the behavior of an entire sample at once, it’s thought to be the most promising way to clarify whether PDW exists and how it relates to other key phases in cuprates, Lee said.

Over the past few years, the SSRL team has worked on increasing the sensitivity of RSXS so it could capture the signals they were looking for.

Postdoctoral researcher Hai Huang and SLAC staff engineer Sang-Jun Lee used the improved technique in this study. They scattered X-rays off LSCFO and into a detector, forming patterns that revealed what was going on inside the material. As they dropped the temperature of the material toward its superconducting range, spin stripes appeared and intertwined to form charge stripes, and those charge stripes were then associated with the emergence of two-dimensional fluctuations that are the hallmark of PDW.

The researchers said these results not only demonstrate the value of the new RSXS approach, but also support the possibility that the PDW is present not just in this material, but in all of the superconducting cuprates.

Reference: “Two-Dimensional Superconducting Fluctuations Associated with Charge-Density-Wave Stripes in La_1.87Sr_0.13Cu_0.99Fe_0.01O₄” by H. Huang, S.-J. Lee, Y. Ikeda, T. Taniguchi, M. Takahama, C.-C. Kao, M. Fujita, and J.-S. Lee, 21 April 2021, Physical Review Letters.
DOI: 10.1103/PhysRevLett.126.167001

A research team led by Masaki Fujita at Tohoku University in Japan grew the high-quality LSCFO crystal used in the experiment and conducted preliminary tests on it there. The research was funded by the DOE Office of Science. SSRL is a DOE Office of Science user facility.

Archaeologists Discover Oldest Direct Evidence for Honey Collecting in Africa in Ancient Clay Pots

Scientists at Goethe University and University of Bristol (UK) find traces of beeswax in prehistoric pottery of the West African Nok culture.

Before sugar cane and sugar beets conquered the world, honey was the worldwide most important natural product for sweetening. Archaeologists at Goethe University in cooperation with chemists at the University of Bristol have now produced the oldest direct evidence of honey collecting of in Africa. They used chemical food residues in potsherds found in Nigeria.

Honey is humankind’s oldest sweetener – and for thousands of years it was also the only one. Indirect clues about the significance of bees and bee products are provided by prehistoric petroglyphs on various continents, created between 8,000 and 40,000 years ago. Ancient Egyptian reliefs indicate the practice of beekeeping as early as 2600 year BCE. But for sub-Saharan Africa, direct archaeological evidence has been lacking until now. The analysis of the chemical residues of food in potsherds has fundamentally altered the picture. Archaeologists at Goethe University in cooperation with chemists at the University of Bristol were able to identify beeswax residues in 3500 year-old potsherds of the Nok culture.

The Nok culture in central Nigeria dates between 1500 BCE and the beginning of the Common Era and is known particularly for its elaborate terracotta sculptures. These sculptures represent the oldest figurative art in Africa. Until a few years ago, the social context in which these sculptures had been created was completely unknown. In a project funded by the German Research Foundation, Goethe University scientists have been studying the Nok culture in all its archaeological facets for over twelve years. In addition to settlement pattern, chronology, and meaning of the terracotta sculptures, the research also focussed on environment, subsistence and diet.

Did the people of the Nok Culture have domesticated animals or were they hunters? Archaeologists typically use animal bones from excavations to answer these questions. But what to do if the soil is so acidic that bones are not preserved, as is the case in the Nok region?

The analysis of molecular food residues in pottery opens up new possibilities. This is because the processing of plant and animal products in clay pots releases stable chemical compounds, especially fatty acids (lipids). These can be preserved in the pores of the vessel walls for thousands of years, and can be detected with the assistance of gas chromatography.

To the researchers’ great surprise, they found numerous other components besides the remains of wild animals, significantly expanding the previously known spectrum of animals and plants used. There is one creature in particular that they had not expected: the honeybee. A third of the examined shards contained high-molecular lipids, typical for beeswax.

It is not possible to reconstruct from the lipids which bee products were used by the people of the Nok culture. Most probably they separated the honey from the waxy combs by heating them in the pots. But it is also conceivable that honey was processed together with other raw materials from animals or plants, or that they made mead. The wax itself could have served technical or medical purposes. Another possibility is the use of clay pots as beehives, as is practiced to this day in traditional African societies.

“We began this study with our colleagues in Bristol because we wanted to know if the Nok people had domesticated animals,” explains Professor Peter Breunig from Goethe University, who is the director of the archaeological Nok project. “That honey was part of their daily menu was completely unexpected, and unique in the early history of Africa until now.”

Dr. Julie Dunne from the University of Bristol, first author of the study says: “This is a remarkable example of how biomolecular information from prehistoric pottery in combination with ethnographic data provides insight into the use of honey 3500 years ago.”

Professor Richard Evershed, Head of the Institute for Organic Chemistry at the University of Bristol and co-author of the study points out that the special relationship between humans and honeybees was already known in antiquity. “But the discovery of beeswax residues in Nok pottery allows a very unique insight into this relationship, when all other sources of evidence are lacking.”

Professor Katharina Neumann, who is in charge of archaeobotany in the Nok project at Goethe University says: “Plant and animal residues from archaeological excavations reflect only a small section of what prehistoric people ate. The chemical residues make previously invisible components of the prehistoric diet visible.” The first direct evidence of beeswax opens up fascinating perspectives for the archaeology of Africa. Neumann: “We assume that the use of honey in Africa has a very long tradition. The oldest pottery on the continent is about 11,000 years old. Does it perhaps also contain beeswax residues? Archives around the world store thousands of ceramic shards from archaeological excavations that are just waiting to reveal their secrets through gas chromatography and paint a picture of the daily life and diet of prehistoric people.”

For more on this research, read Ancient Pottery Reveals First Evidence of Prehistoric Honey Hunting in West Africa 3,500 Years Ago.

Reference: “Honey-collecting in prehistoric West Africa from 3,500 years ago” by Julie Dunne, Alexa Höhn, Gabriele Franke, Katharina Neumann, Peter Breunig, Toby Gillard, Caitlin Walton-Doyle and Richard P. Evershed, 14 April 2021, Nature Communications.
DOI: 10.1038/s41467-021-22425-4

Of Mice and Spacemen: Understanding Astronaut Muscle Wasting at the Molecular Level

Researchers from the University of Tsukuba have sent mice into space to explore effects of spaceflight and reduced gravity on muscle atrophy, or wasting at the molecular level.

Most of us have imagined how free it would feel to float around, like an astronaut, in conditions of reduced gravity. But have you ever considered what the effects of reduced gravity might have on muscles? Gravity is a constant force on Earth which all living creatures have evolved to rely on and adapt to. Space exploration has brought about many scientific and technological advances, yet manned spaceflights come at a cost to astronauts, including reduced skeletal muscle mass and strength.

Conventional studies investigating the effects of reduced gravity on muscle mass and function have used a ground control group that is not directly comparable to the space experimental group. Researchers from the University of Tsukuba set out to explore the effects of gravity in mice subjected to the same housing conditions, including those experienced during launch and landing. “In humans, spaceflight causes muscle atrophy and can lead to serious medical problems after return to Earth,” says senior author Professor Satoru Takahashi. “This study was designed based on the critical need to understand the molecular mechanisms through which muscle atrophy occurs in conditions of microgravity and artificial gravity.”

Two groups of mice (six per group) were housed onboard the International Space Station for 35 days. One group was subjected to artificial gravity (1 g) and the other to microgravity. All mice were alive upon return to Earth and the team compared the effects of the different onboard environments on skeletal muscles.

“To understand what was happening inside the muscles and cells, at the molecular level, we examined the muscle fibers. Our results show that artificial gravity prevents the changes observed in mice subjected to microgravity, including muscle atrophy and changes in gene expression,” explained Prof. Takahashi. Transcriptional analysis of gene expression revealed that artificial gravity prevented altered expression of atrophy related genes and identified novel candidate genes associated with atrophy. Specifically, a gene called Cacng1 was identified as possibly having a functional role in myotube atrophy.

This work supports the use of spaceflight datasets using 1 g artificial gravity for examining the effects of spaceflight in muscles. These studies will likely aid our understanding of the mechanisms of muscle atrophy and may ultimately influence the treatment of related diseases.

Reference: “Transcriptome analysis of gravitational effects on mouse skeletal muscles under microgravity and artificial 1 g onboard environment” by Risa Okada, Shin-ichiro Fujita, Riku Suzuki, Takuto Hayashi, Hirona Tsubouchi, Chihiro Kato, Shunya Sadaki, Maho Kanai, Sayaka Fuseya, Yuri Inoue, Hyojung Jeon, Michito Hamada, Akihiro Kuno, Akiko Ishii, Akira Tamaoka, Jun Tanihata, Naoki Ito, Dai Shiba, Masaki Shirakawa, Masafumi Muratani, Takashi Kudo and Satoru Takahashi, 28 April 2021, Scientific Reports.
DOI: 10.1038/s41598-021-88392-4

Critically Endangered Iconic Great Apes in Borneo Lost Muscle During Fruit Shortages

A male orangutan eating non-fruit vegetation instead of the fruit orangutans prefer on the island of Borneo in Southeast Asia. Credit: Kristana Parinters Makur/Tuanan Orangutan Research Project

Highlights Need to Protect Orangutan Habitat

Wild orangutans are known for their ability to survive food shortages, but scientists have made a surprising finding that highlights the need to protect the habitat of these critically endangered primates, which face rapid habitat destruction and threats linked to climate change.

Scientists found that the muscle mass of orangutans on the island of Borneo in Southeast Asia was significantly lower when less fruit was available. That’s remarkable because orangutans are thought to be especially good at storing and using fat for energy, according to a Rutgers-led study in the journal Scientific Reports.

The findings highlight that any further disruption of their fruit supply could have dire consequences for their health and survival.

“Conservation plans must consider the availability of fruit in forest patches or corridors that orangutans may need to occupy as deforestation continues across their range,” said lead author Caitlin A. O’Connell, a post-doctoral fellow in the lab of senior author Erin R. Vogel, Henry Rutgers Term Chair Professor and an associate professor in the Department of Anthropology and Center for Human Evolutionary Studies in the School of Arts and Sciences at Rutgers University-New Brunswick.

A male orangutan nicknamed Jerry on the island of Borneo. Credit: Cecilia Mayer

Orangutans weigh up to about 180 pounds and live up to 55 years in the wild. One of our closest living relatives, they are the most solitary of the great apes, spending almost all of their time in trees. Orangutans in Borneo also spend some time on the ground. Deforestation linked to logging, the production of palm oil and paper pulp, and hunting all pose threats to orangutans, whose populations have plummeted in recent decades.

Orangutans also face great challenges in meeting their nutritional needs. With low and unpredictable fruit availability in their Southeast Asian forest habitats, they often struggle to eat enough to avoid calorie deficits and losing weight. Because these animals are critically endangered, researchers need to explore new ways to monitor their health without triggering more stress in them.

Researchers in Vogel’s Laboratory for Primate Dietary Ecology and Physiology measured creatinine, a waste product formed when muscle breaks down, in wild orangutan urine to estimate how much muscle the primates had when fruit was scarce versus when it was abundant.

In humans, burning through muscle as the main source of energy marks the third and final phase of starvation, which occurs after stores of body fat are greatly reduced. So, the research team was surprised to find that both males and females of all ages had reduced muscle mass when fruit availability was low compared with when it was high, meaning they had burned through most of their fat reserves and resorted to burning muscle mass.

“Orangutans seem to go through cycles of building fat and possibly muscle mass and then using fat and muscle for energy when preferred fruits are scarce and caloric intake is greatly reduced,” Vogel said. “Our team plans to investigate how other non-invasive measures of health vary with muscle mass and how the increasingly severe wildfires on Borneo might contribute to muscle loss and other negative health impacts.”

Reference: “Wild Bornean orangutans experience muscle catabolism during episodes of fruit scarcity” by Caitlin A. O’Connell, Andrea L. DiGiorgio, Alexa D. Ugarte, Rebecca S. A. Brittain, Daniel J. Naumenko, Sri Suci Utami Atmoko and Erin R. Vogel 13 May 2021, Scientific Reports.
DOI: 10.1038/s41598-021-89186-4

Rutgers co-authors include Andrea L. DiGiorgio, a lecturer at Princeton University and post-doctoral fellow in Vogel’s lab; Alexa D. Ugarte, the lab’s manager; Rebecca S. A. Brittain, a doctoral student in the lab; and Daniel Naumenko, a former Rutgers undergraduate student who is now at doctoral student at the University of Colorado Boulder. Scientists at New York University and Universitas Nasional in Indonesia contributed to the study.

Largest-Ever Effort to Artificially Inseminate Sharks – And the Occasional “Virgin Birth”

A baby bamboo shark born via artificial insemination. Credit: Photo by Jay Harvey, Aquarium of the Pacific

It’s a tough time to be a shark. Pollution, industrialized fishing, and climate change threaten marine life, and the populations of many top ocean predators have declined in recent years.

In addition to studying sharks in the wild, scientists working to save sharks rely on ones living in zoos and aquariums so that they can help build breeding programs and learn more about the conditions sharks need to thrive. One important way the scientists do that is by playing matchmakers to the sharks, pairing up individuals in ways that increase genetic diversity.

In a new study in Scientific Reports, scientists undertook the largest-ever effort to artificially inseminate sharks. Their work resulted in 97 new baby sharks, including ones whose parents live on opposite sides of the country and a few that don’t have fathers at all.

“Our goal was to develop artificial insemination as a tool that could be used to help support and maintain healthy reproducing populations of sharks in aquariums,” says Jen Wyffels, the paper’s lead author who conducted the research for this paper with the South-East Zoo Alliance for Reproduction & Conservation and is currently a researcher at the University of Delaware.

“Moving whole animals from one aquarium to another to mate is expensive and can be stressful for the animal, but now we can just move genes around through sperm,” says Kevin Feldheim, a researcher at Chicago’s Field Museum and a co-author of the study who led the DNA analysis of the newborn sharks to determine their parentage.

Egg cases (aka “mermaid’s purses”) laid by bamboo sharks and fertilized via artificial insemination. Credit: Photo by Jay Harvey, Aquarium of the Pacific

Figuring out shark parentage can be tricky because shark reproduction isn’t always straightforward. In some species, female sharks can store sperm for months after mating and they use it for fertilization “on demand,” so the father of a newborn shark isn’t necessarily the male the mother most recently had contact with. Some female sharks are even capable of reproducing with no male at all, a process called parthenogenesis. In parthenogenesis, the female’s egg cells are able to combine with each other, creating an embryo that only contains genetic material from the mother.

To study shark reproduction, the researchers focused on whitespotted bamboo sharks. “When people think of sharks, they picture great whites, tiger sharks, and bull sharks — the big, scary, charismatic ones,” says Feldheim. “Whitespotted bamboo sharks are tiny, about three feet long. If you go to an aquarium, they’re generally just resting on the bottom.” But while bamboo sharks’ gentleness and small size make them unlikely candidates for Hollywood fame, those qualities make them ideal for researchers to try to artificially inseminate.

Before attempting artificial insemination, researchers have to make sure that the potential mothers aren’t already carrying sperm from a previous rendezvous. “Candidate females are isolated from males and the eggs they lay afterwards are monitored to make sure they are infertile,” says Wyffels. Egg-laying sharks regularly lay eggs on a regular schedule, much like chickens, says Wyffels, to the point that they’re nicknamed “chickens of the sea.” To determine if the eggs are infertile, scientists shine an underwater light through the leathery, rectangular egg cases (called “mermaid’s purses”) to see if there’s a wriggling embryo on top of the yolk. If there are no fertilized eggs for six weeks or more, the shark is ready to be inseminated.

A group of bamboo shark hatchlings in a tube. Credit: Photo by Jay Harvey, Aquarium of the Pacific

Scientists collected and evaluated 82 semen samples from 19 sharks in order to tell the difference between good and bad samples. Some of the good samples went to nearby females for insemination, while others were kept cold and shipped around and across the country. Once the semen reached Ripley’s Aquarium of the Smokies or Aquarium of the Pacific, where a female was waiting, researchers sedated her and placed the semen in her reproductive tract — the procedure took less than ten minutes. All in all, 20 females were inseminated as part of the study.

Baby sharks hatched from fertilized eggs after 4 months of incubation. “The hatchlings are about the size of your hand, and they have distinctive spot patterns that help to tell them apart,” says Wyffels. Tissue samples were taken from all the babies, along with their parents, so Feldheim could analyze their DNA at the Field Museum’s Pritzker Laboratory for Molecular Systematics and Evolution.

Feldheim developed a suite of genetic markers to determine parentage. “We sequenced the DNA and found sections where the code repeats itself,” says Feldheim. “These repeating bits of code serve as signatures, and when we see them in the babies, we match them up to the potential dads.” The team found that freshly collected semen was effective in fertilizing eggs in 27.6% of cases; semen that had been cold-stored for 24 or 48 hours had 28.1% and 7.1% success rates, respectively. In the genetic analysis of the offspring, the team also found two instances of parthenogenesis, where the mother reproduced on her own without using the sperm she’d been inseminated with. “These cases of parthenogenesis were unexpected and help illustrate how little we know about the basic mechanisms of sexual reproduction and embryo development among sharks,” says Wyffels.

From these preliminary results, the scientists hope to help aquariums expand and manage their shark breeding programs. “There have been other reports on artificial insemination of sharks, but they include very few females. In this study, we’re in the double digits and as a result we could investigate different methods for preparing and preserving sperm for insemination” says Wyffels. “And a hatchling from shark parents that live almost 3,000 miles apart from sperm collected days in advance, that’s definitely a first.”

“One of the goals of this pilot project was to just see if it worked,” says Feldheim. “Now, we can extend it to other animals that actually need help breeding, from other species in aquariums to sharks under threat in the wild.”

The researchers also note that if studies like these contribute to the conservation of sharks in the wild, it will be largely thanks to aquariums. “We wouldn’t know about parthenogenesis in sharks if it wasn’t for aquariums,” says Feldheim.

“Aquariums allow you to observe the same individual animals over time, and that’s very difficult to do in the wild,” says Wyffels. “Aquarists have eyes on their animals every day. They pick up on subtle changes in behavior related to reproduction, and they tell us what they see. Research like this depends on that collaboration. We are already taking what we learned from this study and applying it to other species, especially the sand tiger shark, a protected species that does not reproduce often in aquariums.”

Reference: “Artificial insemination and parthenogenesis in the whitespotted bamboo shark Chiloscyllium plagiosum” by Jennifer T. Wyffels, Lance M. Adams, Frank Bulman, Ari Fustukjian, Michael W. Hyatt, Kevin A. Feldheim & Linda M. Penfold 13 May 2021, Scientific Reports.
DOI: 10.1038/s41598-021-88568-y

This study was led by researchers from the South-East Zoo Alliance for Reproduction & Conservation in collaboration with, the Aquarium of the Pacific, Ripley’s Aquarium of the Smokies, The Florida Aquarium, Adventure Aquarium and the Field Museum.

Hear the Eerie Sounds of Interstellar Space Captured by NASA’s Voyager

An illustration depicting one of NASA’s twin Voyager spacecraft. Both Voyagers have entered interstellar space, or the space outside our Sun’s heliosphere. Credit: NASA/JPL-Caltech

As NASA’s Voyager 1 Surveys Interstellar Space, Its Density Measurements Are Making Waves

In the sparse collection of atoms that fills interstellar space, Voyager 1 has measured a long-lasting series of waves where it previously only detected sporadic bursts.

Until recently, every spacecraft in history had made all of its measurements inside our heliosphere, the magnetic bubble inflated by our Sun. But on August 25, 2012, NASA’s Voyager 1 changed that. As it crossed the heliosphere’s boundary, it became the first human-made object to enter – and measure – interstellar space. Now eight years into its interstellar journey, a close listen of Voyager 1’s data is yielding new insights into what that frontier is like.

If our heliosphere is a ship sailing interstellar waters, Voyager 1 is a life raft just dropped from the deck, determined to survey the currents. For now, any rough waters it feels are mostly from our heliosphere’s wake. But farther out, it will sense the stirrings from sources deeper in the cosmos. Eventually, our heliosphere’s presence will fade from its measurements completely.

This graphic from October 20218 shows the position of the Voyager 1 and Voyager 2 probes relative to the heliosphere, a protective bubble created by the Sun that extends well past the orbit of Pluto. Voyager 1 crossed the heliopause, or the edge of the heliosphere, in 2012. Voyager 2 is still in the heliosheath, or the outermost part of the heliosphere. (NASA’s Voyager 2 spacecraft entered interstellar space in November 2018.) Credits: NASA/JPL-Caltech

“We have some ideas about how far Voyager will need to get to start seeing more pure interstellar waters, so to speak,” said Stella Ocker, a Ph.D. student at Cornell University in Ithaca, New York, and the newest member of the Voyager team. “But we’re not entirely sure when we’ll reach that point.”

Ocker’s new study, published on Monday in Nature Astronomy, reports what may be the first continuous measurement of the density of material in interstellar space. “This detection offers us a new way to measure the density of interstellar space and opens up a new pathway for us to explore the structure of the very nearby interstellar medium,” Ocker said.

NASA’s Voyager 1 spacecraft captured these sounds of interstellar space. Voyager 1’s plasma wave instrument detected the vibrations of dense interstellar plasma, or ionized gas, from October to November 2012 and April to May 2013. Credit: NASA/JPL-Caltech

When one pictures the stuff between the stars – astronomers call it the “interstellar medium,” a spread-out soup of particles and radiation – one might reimagine a calm, silent, serene environment. That would be a mistake.

“I have used the phrase ‘the quiescent interstellar medium’ – but you can find lots of places that are not particularly quiescent,” said Jim Cordes, space physicist at Cornell and co-author of the paper.

Like the ocean, the interstellar medium is full of turbulent waves. The largest come from our galaxy’s rotation, as space smears against itself and sets forth undulations tens of light-years across. Smaller (though still gigantic) waves rush from supernova blasts, stretching billions of miles from crest to crest. The smallest ripples are usually from our own Sun, as solar eruptions send shockwaves through space that permeate our heliosphere’s lining.

These crashing waves reveal clues about the density of the interstellar medium – a value that affects our understanding of the shape of our heliosphere, how stars form, and even our own location in the galaxy. As these waves reverberate through space, they vibrate the electrons around them, which ring out at characteristic frequencies depending on how crammed together they are. The higher the pitch of that ringing, the higher the electron density. Voyager 1’s Plasma Wave Subsystem – which includes two “bunny ear” antennas sticking out 30 feet (10 meters) behind the spacecraft – was designed to hear that ringing.

An illustration of NASA’s Voyager spacecraft showing the antennas used by the Plasma Wave Subsystem and other instruments. Credit: NASA/JPL-Caltech

In November 2012, three months after exiting the heliosphere, Voyager 1 heard interstellar sounds for the first time (see video above). Six months later, another “whistle” appeared – this time louder and even higher pitched. The interstellar medium appeared to be getting thicker, and quickly.

These momentary whistles continue at irregular intervals in Voyager’s data today. They’re an excellent way to study the interstellar medium’s density, but it does take some patience.

“They’ve only been seen about once a year, so relying on these kinds of fortuitous events meant that our map of the density of interstellar space was kind of sparse,” Ocker said.

Ocker set out to find a running measure of interstellar medium density to fill in the gaps – one that doesn’t depend on the occasional shockwaves propagating out from the Sun. After filtering through Voyager 1’s data, looking for weak but consistent signals, she found a promising candidate. It started to pick up in mid-2017, right around the time of another whistle.

“It’s virtually a single tone,” said Ocker. “And over time, we do hear it change – but the way the frequency moves around tells us how the density is changing.”

Weak but nearly continuous plasma oscillation events – visible as a thin red line in this graphic/tk – connect stronger events in Voyager 1’s Plasma Wave Subsystem data. The image alternates between graphs showing only the strong signals (blue background) and the filtered data showing weaker signals. Credit: NASA/JPL-Caltech/Stella Ocker

Ocker calls the new signal a plasma wave emission, and it, too, appeared to track the density of interstellar space. When the abrupt whistles appeared in the data, the tone of the emission rises and falls with them. The signal also resembles one observed in Earth’s upper atmosphere that’s known to track with the electron density there.

“This is really exciting, because we are able to regularly sample the density over a very long stretch of space, the longest stretch of space that we have so far,” said Ocker. “This provides us with the most complete map of the density and the interstellar medium as seen by Voyager.”

Based on the signal, electron density around Voyager 1 started rising in 2013 and reached its current levels about mid-2015, a roughly 40-fold increase in density. The spacecraft appears to be in a similar density range, with some fluctuations, through the entire dataset they analyzed which ended in early 2020.

Ocker and her colleagues are currently trying to develop a physical model of how the plasma wave emission is produced that will be key to interpreting it. In the meantime, Voyager 1’s Plasma Wave Subsystem keeps sending back data farther and farther from home, where every new discovery has the potential to make us reimagining our home in the cosmos.

For more on this research, read In the Emptiness of Space 14 Billion Miles Away, Voyager I Detects “Hum” From Plasma Waves.

Reference: “Persistent plasma waves in interstellar space detected by Voyager 1” by Stella Koch Ocker, James M. Cordes, Shami Chatterjee, Donald A. Gurnett, William S. Kurth and Steven R. Spangler, 10 May 2021, Nature Astronomy.
DOI: 10.1038/s41550-021-01363-7

DNA Analysis Identifies First Member of Ill-Fated 1845 Franklin Expedition

Facial reconstruction of individual identified through DNA analysis as John Gregory, HMS Erebus. Credit: Diana Trepkov/ University of Waterloo

With a living descendant’s DNA sample, a team of researchers have identified the remains of John Gregory, engineer aboard HMS Erebus.

The identity of the skeletal remains of a member of the 1845 Franklin expedition has been confirmed using DNA and genealogical analyses by a team of researchers from the University of Waterloo, Lakehead University, and Trent University. This is the first member of the ill-fated expedition to be positively identified through DNA.

DNA extracted from tooth and bone samples recovered in 2013 were confirmed to be the remains of Warrant Officer John Gregory, engineer aboard HMS Erebus. The results matched a DNA sample obtained from a direct descendant of Gregory.

Douglas Stenton excavating an as-yet unidentified sailor whose remains were found with those of John Gregory. Credit: Robert W. Park/ University of Waterloo

The remains of the officer were found on King William Island, Nunavut. “We now know that John Gregory was one of three expedition personnel who died at this particular site, located at Erebus Bay on the southwest shore of King William Island,” says Douglas Stenton, adjunct professor of anthropology at Waterloo and co-author of a new paper about the discovery.

“Having John Gregory’s remains being the first to be identified via genetic analysis is an incredible day for our family, as well as all those interested in the ill-fated Franklin expedition,” said Gregory’s great-great-great grandson Jonathan Gregory of Port Elizabeth, South Africa. “The whole Gregory family is extremely grateful to the entire research team for their dedication and hard work, which is so critical in unlocking pieces of history that have been frozen in time for so long.”

Sir John Franklin’s 1845 northwest passage expedition, with 129 sailors on two ships, Erebus and Terror, entered the Arctic in 1845. In April 1848, 105 survivors abandoned their ice-trapped ships in a desperate escape attempt. None would survive. Since the mid-19th century, skeletal remains of dozens of crew members have been found on King William Island, but none had been positively identified.

To date, the DNA of 26 other members of the Franklin expedition have been extracted from remains found in nine archaeological sites situated along the line of the 1848 retreat. “Analysis of these remains has also yielded other important information on these individuals, including their estimated age at death, stature, and health,” says Anne Keenleyside, Trent anthropology professor and co-author of the paper.

“We are extremely grateful to the Gregory family for sharing their family history with us and for providing DNA samples in support of our research. We’d like to encourage other descendants of members of the Franklin expedition to contact our team to see if their DNA can be used to identify the other 26 individuals,” says Stenton.

Commemorative cairn at Erebus Bay constructed in 2014. The cairn contains the remains of John Gregory and two other members of the 1845 Franklin expedition. Credit: Diana Trepkov/ University of Waterloo

Genealogical records indicated a direct, five-generation paternal relationship between the living descendant and John Gregory. “It was fortunate that the samples collected contained well-preserved genetic material, says Stephen Fratpietro of Lakehead’s Paleo-DNA lab, who is a co-author.

Prior to this DNA match, the last information about his voyage known to Gregory’s family was in a letter he wrote to his wife Hannah from Greenland on 9 July 1845 before the ships entered the Canadian Arctic.

This latest discovery helps to complete the story of the Franklin victims, says Robert Park, Waterloo anthropology professor and co-author. “The identification proves that Gregory survived three years locked in the ice on board HMS Erebus. But he perished 75 kilometers south at Erebus Bay.”

The remains of Gregory and two others were first discovered in 1859 and buried in 1879. The grave was rediscovered in 1993, and in 1997 several bones that had been exposed through disturbance of the grave were placed in a cairn with a commemorative plaque. The grave was then excavated in 2013 and after being analyzed, all the remains were returned to the site in 2014 and placed in a new larger memorial cairn.

Reference: “DNA identification of a sailor from the 1845 Franklin northwest passage expedition” by Douglas R. Stenton, Stephen Fratpietro, Anne Keenleyside and Robert W. Park, 28 April 2021, Polar Record.
DOI: 10.1017/S0032247421000061

DNA identification of a sailor from the 1845 Franklin Northwest Passage Expedition by Stenton, Park, Fratpietro, and Keenleyside was published in the journal Polar Record. The research was funded by the Government of Nunavut, Trent University and the University of Waterloo. Descendants of members of the Franklin expedition can contact Douglas Stenton or Anne Keenleyside.

Handheld “MasSpec Pen” Reveals Meat and Fish Fraud in Seconds

The MasSpec Pen can authenticate the type and purity of meat samples in as little as 15 seconds. Credit: Adapted from Journal of Agricultural and Food Chemistry 2021, DOI: 10.1021/acs.jafc.0c07830

Meat and fish fraud are global problems, costing consumers billions of dollars every year. On top of that, mislabeling products can cause problems for people with allergies, religious or cultural restrictions. Current methods to detect this fraud, while accurate, are slower than inspectors would like. Now, researchers reporting in ACS’ Journal of Agricultural and Food Chemistry have optimized their handheld MasSpec Pen to identify common types of meat and fish within 15 seconds.

News stories of food fraud, such as beef being replaced with horse meat, and cheaper fish being branded as premium fillets, have led people to question if what is on the label is actually in the package. To combat food adulteration, the U.S. Department of Agriculture conducts regular, random inspections of these products.

Although current molecular techniques, such as the polymerase chain reaction (PCR), are highly accurate, these analyses can take hours to days, and are often performed at off-site labs. Previous studies have devised more direct and on-site food analysis methods with mass spectrometry, using the amounts of molecular components to verify meat sources, but they also destroyed samples during the process or required sample preparation steps.

More recently, Livia Eberlin and colleagues developed the MasSpec Pen — a handheld device that gently extracts compounds from a material’s surface within seconds and then analyzes them on a mass spectrometer. So, the team wanted to see whether this device could rapidly and effectively detect meat and fish fraud in pure filets and ground products.

The researchers used the MasSpec Pen to examine the molecular composition of grain-fed and grass-fed beef, chicken, pork, lamb, venison, and five common fish species collected from grocery stores. Once the device’s tip was pressed against a sample, a 20-μL droplet of solvent was released, extracting sufficient amounts of molecules within three seconds for accurate analysis by mass spectrometry. The whole process took 15 seconds, required no preprocessing, and the liquid extraction did not harm the samples’ surfaces.

Then the team developed authentication models using the unique patterns of the molecules identified, including carnosine, anserine, succinic acid, xanthine and taurine, to distinguish pure meat types from each other, beef based on feeding habit and among the five fish species.

Finally, the researchers applied their models to the analysis of test sets of meats and fish. For these samples, all models had a 100% accuracy identifying the protein source, which is as good as the current method of PCR and approximately 720 times faster.

The researchers say they plan to expand the method to other meat products and integrate the MasSpec Pen into a portable mass spectrometer for on-site meat authentication.

Reference: “Rapid Analysis and Authentication of Meat Using the MasSpec Pen Technology” by Abigail N. Gatmaitan, John Q. Lin, Jialing Zhang and Livia S. Eberlin, 10 March 2021, Journal of Agricultural and Food Chemistry.
DOI: 10.1021/acs.jafc.0c07830

The authors acknowledge funding from the Welch Foundation and the Gordon and Betty Moore Foundation.