Exercised over nothing: Masks don't impair lung function during physical activity

While they might feel uncomfortable, researchers report facemasks do not significantly change the actual work of breathing or the flow of oxygen and carbon dioxide when worn while exercising

UNIVERSITY OF CALIFORNIA - SAN DIEGO

Research News

Wearing a facemask helps limit the spread of COVID-19 by reducing respiratory droplets and aerosols spewed into the air when people breathe, talk, laugh, sneeze or cough. But the physical barrier created by masks has prompted concerns that they might impair the cardiopulmonary system by making it harder to breathe, by altering the flow of inhaled oxygen and exhaled carbon dioxide and by increasing dyspnea -- a medical term that describe shortness of breath or difficulty breathing, especially during physical activity.

In a new study, published November 16, 2020 in the Annals of the American Thoracic Society, a team of American and Canadian researchers concluded that while sensations of dyspnea might increase, there is little empirical evidence that wearing a facemask significantly diminishes lung function, even when worn during heavy exercise.

"There might be a perceived greater effort with activity, but the effects of wearing a mask on the work of breathing, on gases like oxygen and CO2 in blood or other physiological parameters are small, often too small to be detected," said the study's first author Susan Hopkins, MD, PhD, professor of medicine and radiology at University of California San Diego School of Medicine.

"There's also no evidence to support any differences by sex or age in physiological responses to exercise while wearing a facemask," added Hopkins, who specializes in exercise physiology and the study of lungs under stress.

The single exception, the authors note, may be persons with severe cardiopulmonary disease in which any added resistance to breathing or minor changes in blood gases could prompt dyspnea great enough to affect exercise capacity.

"In such cases, these individuals might feel too uncomfortable to exercise, and that should be discussed with their doctor," Hopkins said. "However, the fact that these individuals are at great risk should they contract COVID-19 must also be considered"

The researchers came to their conclusions following a review of all known scientific literature published that examined the effects of various facemasks and respiratory loading devices on physiological and perceptual responses to physical activity. These studies assessed multiple factors, such as work of breathing (the quantified energy expended to inhale and exhale), arterial blood gases, effects on muscle blood flow and fatigue, cardiac function and flow of blood to the brain.

For healthy persons, the effects of wearing a mask on these physiological markers were minimal, no matter what type of mask was worn or the degree of exercise. The authors also said age played no significant influencing role among adults. Gender differences were deemed inconsequential.

"Wearing a facemask can be uncomfortable," said Hopkins. "There can be tiny increases in breathing resistance. You may re-inhale warmer, slightly enriched CO2 air. And if you're exercising, the mask can cause your face to become hot and sweaty.

"But these are sensory perceptions. They do not impact cardiopulmonary function in healthy people. So while dyspnea might be increased with a mask, you have to weigh that against the reduced risk of contracting COVID-19, knowing that the physiology is essentially unchanged."

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Co-authors include: Paolo B. Dominelli, University of Waterloo, Ontario, Canada; Christopher K. Davis, UC San Diego and Rady Children's Hospital-San Diego; Jordan Guenette and William Sheel, University of British Columbia; Andrew M. Luks and Erik R. Swenson, University of Washington; Yannick Molgat-Seon, University of Winnipeg, Manitoba, Canada; Rui Carlos Sá, UC San Diego; and Michael K. Stickland, University of Alberta, Edmonton, Canada.

Field research has changed, and so should ethical guidelines, Brown professor says

BROWN UNIVERSITY

Research News

PROVIDENCE, R.I. [Brown University] -- The old ethics rules are no longer offering adequate protection to field research subjects, according to two leading social scientists from Brown and Pennsylvania State Universities -- and as a result, individual people and even entire societies are being left vulnerable to financial ruin, emotional manipulation and more.

In a peer-reviewed essay, Rose McDermott, a professor of international relations at Brown, and Peter K. Hatemi, a professor of political science at Pennsylvania State, argue that the advent of computers, the internet and social media have yielded massive change in the design and execution of certain types of large field experiments -- change that traditional ethics guidelines couldn't have anticipated.

Equipped with no widespread formal guidelines on securing voluntary consent in the internet age, scientists are designing big experiments that can, and often do, cause harm, McDermott and Hatemi say. But if research institutions, leading journals and scientific professional organizations were to publish and enforce updated ethical standards, scientists might better understand how to gather important insights without unintentionally damaging people and societies.

"The concern we're voicing is that early ethical guidance doesn't account for field experiments on huge numbers of people, because these experiments weren't common or even possible before the 1990s," McDermott said. "There's evidence that some of these recent experiments have stoked racial resentment, changed election outcomes and caused huge societal divisions. We're not saying these kinds of big field experiments aren't valuable -- we're saying we need to come up with ways to do it ethically."

McDermott's and Hatemi's essay was published as a "Perspective" piece on Monday, Nov. 15 in the journal Proceedings of the National Academy of Sciences. Perspective pieces undergo the same submission and review processes as research reports, but rather than describing the results of original research, they present a balanced, objective and thoroughly researched viewpoint on a specific field.

McDermott said that when today's scientists design experiments, they most often refer to ethical guidelines written decades ago, such as the Declaration of Helsinki -- a much-revised medical ethics guide first written in 1964 -- and the 1979 report "Ethical Principles and Guidelines for the Protection of Human Subjects of Research," now commonly known as the Belmont Report. But those guidelines, she said, were not created with computers, the internet and social media in mind.

"You've had a rise in the ability to do massive computing projects and analyze lots of data very quickly," McDermott said. "With social media platforms, you can have all kinds of access to huge populations. Combine with that the immense pressure on academics to publish high-impact research quickly and frequently, and you've got a world that looks very different than it did when the Belmont Report was published."

As a result, McDermott said, researchers have recently undertaken studies that made important discoveries but also changed people's behaviors, caused them trauma or even financially endangered them.

For example, several studies that have sought to identify what increases or depresses voter turnout have unintentionally altered election outcomes by influencing voters with racially-charged mailers and phone calls and door-to-door visits from fake political candidates. Scientists seeking to understand how social media alters people's moods and political affiliations have inadvertently engaged in the emotional manipulation of hundreds of thousands of people by pushing certain types of posts to their feeds. And many studies investigating the benefits and drawbacks of financial assistance have purposely given or withheld money from research subjects, causing them to become homeless or suffer from increased domestic violence.

"Science is a process of trial and error, and I think in the early days of large field experiments, people couldn't anticipate what might happen to the subjects," McDermott said. "But now we do know what can happen if we're not careful. We need to stop, take a breath and take stock of the damage some of these experiments have done so that we can learn from those mistakes and implement changes."

Those changes, McDermott and Hatemi argue, must come primarily from the top down. In their essay, the two scholars called on academic professional associations, journals and research institutions to update their policies to not only adhere to existing ethical norms but also formulate new requirements to address potential harm in large-scale field experiments that impact entire populations.

McDermott said she hopes the PNAS essay helps spur the kind of systemic change Henry Knowles Beecher kickstarted with his famous 1966 essay exposing unethical practices in the field of medical experimentation. Beecher's investigation eventually led to the passage of federal rules requiring scientists to obtain informed consent from study participants.

"While we would be happy to see individual scholars and individual universities addressing issues of informed consent in their field research, real change can only happen if it's systemic," McDermott said. "It's just like reversing climate change: Yes, it's good that you bought a Prius, but really what we need is for governments to shut down coal-fired plants. All of the institutions that hold power in science need to work in concert."

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New study could help predict which individuals are more susceptible to cancer-causing agent

UNIVERSITY OF BIRMINGHAM

Research News

 

New insights into the mechanisms behind how cancer-causing agents in the environment activate genetic recombination in DNA could help to explain some of the effects of exposure as well as predicting which individuals may be more susceptible to developing the disease, a new UK study has suggested.

Everyone is exposed to low levels of carcinogens (substances or radiation that promote the formation of cancer) in the environment. One of the most widely found is benzopyrene - a general chemical pollutant found in smoke from stoves such as wood burners, exhaust fumes and barbequed meat and fish. One active ingredient of benzopyrene, BPDE, directly damages the DNA sequence forming what is known as adducts which in turn promote cancer-causing mutations.

While models exist showing how BPDE causes these mutations, some of the pathways are still not understood. It is currently believed that a BPDE adducts cause mutations during DNA synthesis because they activate a process called translesion synthesis - where cells copy the DNA despite the presence of unrepaired damage to allow progression of the replication fork - and this induces mutations. However, evidence also suggests the involvement of another process called homologous recombination (HR) which works by copying other undamaged parts of the genome. HR proteins repair complex DNA damage such as breaks in the DNA strands and interstrand cross-links, and protect and recover stalled or broken replication forks.

This latest study treated human cell lines with BPDE before using molecular biology methods, such as microscopy, to characterise the homologous recombination pathway in detail. Results have offered new insights showing that HR proceeds by an unusual mechanism at BPDE adducts and the process can be activated even when there are no stalled or collapsed replication forks. Instead, it is activated at single-stranded gaps in the DNA that are generated by the re-priming activity of PrimPol - a protein encoded by the PRIMPOL gene in humans.

The findings also address longstanding questions by showing that at bulky DNA adducts, the exchanges between the sister chromatids (the identical copies formed by the DNA replication of a chromosome), products of HR that have been traditionally connected with replication fork collapse and DSB repair, are associated with the repair of post-replicative gaps. Furthermore, these post-replicative gaps are produced by PrimPol, shedding light on the function of PrimPol during DNA damage tolerance.

Corresponding author Dr Eva Petermann from the University of Birmingham's Institute of Cancer and Genomic Sciences, says: "Our study has revealed new insights into the effects of benzopyrene exposure in cells, which is important for understanding environmental causes of cancer and cancer development in general. Understanding this mechanism could help to better predict and detect negative effects of pollution as well as allowing for better interpretation of cancer genomics. For example, genetic variants in the HR genes BRCA2 and RAD52 have been liked to lung cancer susceptibility meaning that understanding how HR helps cell deal with benzopyrene could help us to predict individuals who may be more susceptible to the disease

"Moving forwards it will be important to investigate the impact of such genetic variants on HR at ssDNA gaps. A PRIMPOL variant has also been suggested to play a potential role in cancer. It could also help predict which individuals will be more sensitive to carcinogen exposure."

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The paper 'PrimPol-dependent single-stranded gap formation mediates homologous recombination at bulky DNA adducts' was published today (17 November) in Nature Communications.r

Existing antidepressant helps to inhibit growth of cancer cells in lab animals

KU LEUVEN

Research News

 

New research has shown that the antidepressant sertraline helps to inhibit the growth of cancer cells. The substance acts on a metabolic addiction that allows different types of cancer to grow. This is shown by a study on cell cultures and lab animals performed by various research labs of KU Leuven. Their findings were published in Molecular Cancer Therapeutics, a journal of the American Association for Cancer Research.

Cancer cells use different biological mechanisms to stimulate their growth. In certain types of breast cancer, leukaemia, skin cancer, brain tumours and lung cancer, among others, the malignant cells produce large amounts of serine and glycine, two amino acids. This production stimulates the growth of cancer cells to such an extent that they become addicted to serine and glycine.

"This mechanism is an interesting target because cancer cells are so dependent on it", says Professor Kim De Keersmaecker, head of the Laboratory for Disease Mechanisms in Cancer (LDMC). "Healthy cells use this mechanism to a lesser extent and also take up serine and glycine from food. This is not sufficient for cancer cells, however, meaning they start producing more. If we can halt this production, we will be able to fight the cancer without affecting healthy cells."

From yeast to mice

In their search of a substance that influences the synthesis of serine and glycine, the researchers utilized a database of existing medicines. In a first phase, Professor Bruno Cammue's research group at the Centre for Microbial and Plant Genetics (CMPG) tested 1,600 substances on yeast cells.

"Because there are also yeasts, or moulds, which depend on the same mechanism", explains research coordinator Dr Karin Thevissen. "Certain yeasts produce these amino acids to protect themselves against antifungals. In addition, you can easily grow yeast cells, allowing you to test many different substances."

The screening showed that the antidepressant sertraline was the most effective substance. "Other studies had already indicated that sertraline has a certain anti-cancer activity, but there was no explanation for this yet", mention researchers Shauni Geeraerts (LDMC and CMPG) and Kim Kampen (LDMC). "In this study, we've been able to demonstrate that sertraline inhibits the production of serine and glycine, causing decreased growth of cancer cells. We also found that this substance is most effective in combination with other therapeutic agents. In studies with mice we saw that sertraline in combination with another therapy strongly inhibits the growth of breast cancer cells."

Considerable potential

"Now that we've been able to identify this mechanism for breast cancer, we can start examining other types of cancer that are also addicted to serine and glycine synthesis", says Professor De Keersmaecker. "This is for example the case in T-cell leukaemia, but also in certain types of brain, lung and skin cancer. The more tumours we can identify that are sensitive to sertraline, the better the prospects are for helping patients in the future."

"These are, of course, results of experimental research, not clinical studies, but we can be optimistic about the potential. The safety of using sertraline in humans has already been well described, which is a great advantage. That's why we are also looking for industrial partners to develop this further."

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Reducing aerosol pollution without cutting carbon dioxide could make the planet hotter

Solving one environmental problem could create another

UNIVERSITY OF CALIFORNIA - RIVERSIDE

Research News

 

IMAGE: A SYSTEM OF CURRENTS KNOWN AS THE ATLANTIC MERIDIONAL OVERTURNING CIRCULATION CARRIES WARM WATER INTO THE NORTH ATLANTIC. IT COULD BE DISTURBED IF CO2 AND AEROSOLS ARE NOT SIMULTANEOUSLY CUT. view more 

CREDIT: R. CURRY, WOODS HOLE OCEANOGRAPHIC INSTITUTION/SCIENCE/USGCRP

Humans must reduce carbon dioxide and aerosol pollution simultaneously to avoid weakening the ocean's ability to keep the planet cool, new research shows.

Aerosol pollution refers to particles in the air emitted by vehicles and factories that burn fossil fuels. This pollution contributes to asthma, bronchitis, and long-term irritation of the respiratory tract, which can lead to cancer.

"The conundrum," explained UC Riverside climate scientist and study co-author Robert Allen, "is that aerosols cause poor air quality and lead to premature deaths. However, these particles have a net cooling impact on the climate, so when you cut them that leads to a net warming effect."

Much research has examined aerosol impacts on air quality and land surface temperatures. Less explored is the way aerosols might impact the oceans, which is the focus of a UC Riverside study now published in the journal Science Advances.

The research team created detailed computer models to determine the impact on oceans under two different scenarios -- one in which there is only a reduction in aerosols, and another scenario in which greenhouse gases like carbon dioxide and methane are also reduced.

"The first scenario leads to the surprising result that fewer aerosols in the atmosphere could shift the region where most of the ocean is taking up heat, from the Southern Ocean toward the North Atlantic," Allen said.

In particular, the Atlantic meridional overturning circulation, or AMOC, would be disturbed as aerosols are removed from the atmosphere, the study found. The AMOC pulls warm water further north and pushes colder water south, ensuring the climate on land areas at higher latitudes, such as Europe, are relatively mild.

Roughly half the carbon dioxide humans put into the atmosphere -- mostly through fossil fuel combustion and deforestation -- stays there, and the remaining half is taken up by land and vegetation, as well as the ocean.

One of the ways the ocean takes up our carbon dioxide emissions is through AMOC circulation.

"A projected decline in manmade aerosols potentially induces a weakening of the AMOC, which plays an important role in ocean heat uptake and storage in the North Atlantic," said Wei Liu, an assistant professor of climate change and sustainability at UCR.

In addition, the researchers said a rise in sea level would occur if the North Atlantic Ocean were to get warmer.

This current study focused on ocean heat uptake and circulation via the AMOC. However, Allen explained the study did not attempt to rigorously identify the mechanisms by which aerosol reductions weaken the AMOC. Those mechanisms will be the focus of future studies.

Ultimately, the researchers conclude that even without a more in-depth explanation of the weakening mechanisms, it is necessary to reduce greenhouse gases and aerosols in tandem.

The Intergovernmental Panel on Climate Change recommends making every attempt to prevent the planet from reaching 1.5 degrees Celsius above pre-industrial levels in order to mitigate the worst effects of global warming.

Humans have already increased carbon dioxide levels by almost 50% since the 1850s, and it continues to increase worldwide. Stabilizing carbon dioxide at current levels would require zero net emissions before the year 2070, which is ambitious, but critical.

"Assuming complete removal, aerosols at most will cause warming of about 1 K," said Allen. "However, aerosol-induced warming, as well as the associated ocean circulation changes, can be moderated by rigorous cuts in greenhouse gases including methane and carbon dioxide."

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Tropical peatland conservation could protect humans from new diseases

UNIVERSITY OF EXETER

Research News

 

IMAGE: LOCAL FISHERS WORKING UNDER THICK HAZE CONDITIONS FROM PEATLAND FIRES IN CENTRAL KALIMANTAN, INDONESIA. view more 

CREDIT: SUZANNE TURNOCK / BORNEO NATURE FOUNDATION

Conservation of tropical peatlands could reduce the impacts of the COVID-19 pandemic and the likelihood of new diseases jumping from animals to humans, researchers say.

The scientists reviewed existing evidence and concluded the high biodiversity in tropical peat-swamp forests, combined with habitat destruction and wildlife harvesting, created "suitable conditions" for emerging infectious diseases (EIDs) that could jump to humans.

COVID-19 did not emerge in a tropical peatland area - but HIV/AIDS and the joint-first case of Ebola both originated in areas with extensive peatlands.

The study also assessed the possible impact of COVID-19 on tropical peatland conservation and local communities - and identified "numerous potential threats" to both.

Led by the University of Exeter, the international study team comprised researchers from countries with large tropical peatlands, including Indonesia, DR Congo and Perú.

"We're not saying tropical peatlands are unique in this respect - but they are one important habitat where zoonotic diseases (those that jump from animals to humans) could emerge," said lead author Dr Mark Harrison, of the Centre for Ecology and Conservation on Exeter's Penryn Campus in Cornwall, UK and Borneo Nature Foundation International.

"Tropical peat-swamp forests are rich in fauna and flora, including numerous vertebrates known to represent zoonotic EID risk, such as bats, rodents, pangolins and primates.

"Exploitation and fragmentation of these habitats, as well as peat wildfires (ultimately driven by human activity) and wildlife harvesting bring more and more people into close contact with peatland biodiversity, increasing the potential for zoonotic disease transmission.

"Our review shows that protecting tropical peatlands isn't therefore just about wildlife and carbon emissions - it's also important for human health."

The study also notes "high impacts" of COVID-19 in some countries with large tropical peatland areas, some of which are relatively poorly resourced to tackle pandemics.

"Many communities in these areas are remote, relatively poor, disconnected, have limited infrastructure, sub-standard or non-existent medical facilities, and depend heavily on external trade," said Dr Ifo Suspense, of Université Marien, Republic of Congo, who contributed to the review.

"As a result, the direct and indirect impacts of COVID-19 may be particularly severe in these communities."

Dr Muhammad Ali Imron, from University Gadjah Mada in Indonesia, who was also involved in the study, said: "Additionally, major wildfires in peatland areas cause massive air pollution, particularly in South East Asia, increasing the threat to human health from respiratory diseases like COVID-19.

"In terms of the impacts on peatlands themselves, we reveal that conservation, research and training are all being affected by the pandemic, which may result in increased habitat encroachment, wildlife harvesting and fires started to clear vegetation".

The study concludes: "Sustainable management of tropical peatlands and their wildlife is important for mitigating impacts of the COVID-19 pandemic, and reducing the potential for future zoonotic EID emergence and severity, thus strengthening arguments for their conservation and restoration."

To help achieve this, the study identifies a number of opportunities and recommendations for researchers, field projects, policy makers and donors to help achieve this goal.

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The paper, published in the journal PeerJ, is entitled: "Tropical peatlands and their conservation are important in the context of COVID-19 and potential future (zoonotic) disease pandemics."

CAPTION

Peatland fire encroaching into forest in Central Kalimantan, Indonesia.

US agricultural water use declining for most crops and livestock production

UNIVERSITY OF ILLINOIS COLLEGE OF AGRICULTURAL, CONSUMER AND ENVIRONMENTAL SCIENCES

Research News

 

URBANA, Ill. - Climate change and a growing world population require efficient use of natural resources. Water is a crucial component in food production, and water management strategies are needed to support worldwide changes in food consumption and dietary patterns.

Agricultural production and food manufacturing account for a third of water usage in the U.S. Water use fluctuates with weather patterns but is also affected by shifts in production technology, supply-chain linkages, and domestic and foreign consumer demand.

A comprehensive University of Illinois study looked at water withdrawals in U.S. agriculture and food production from 1995 to 2010. The main trend was a decline in water use, driven by a combination of factors.

"Overall, the use of water for irrigation decreased by 8.3% over this period," says Sandy Dall'erba, regional economist at U of I and co-author on the study.

"However, one needs to identify the drivers of water use by crop as they differ from one commodity to the next, so water-saving strategies for one crop may not be relevant for another one," Dall'erba explains. "For instance, water use in cereal grains, fruits, and vegetables is mostly driven by the efficiency of the irrigation system, domestic per-capita income, and sales to the food processing industry. If irrigation is more efficient, water demand decreases. When demand for fruits and vegetables decreased in 2005-2010 during the financial crisis, so did demand for water."

Oilseed crops, on the other hand, have experienced a 98% increase in water demand over the period. The change is primarily driven by international supply-chain linkages. It means foreign companies, mostly in China, have purchased large amount of U.S. oilseed crops for further processing.

"There has also been a shift in consumer demand from red meat to white meat in the U.S. People consume less beef and more chicken, which require 3.5 times less water per pound of production. Those trends in consumption and taste have helped the U.S. reduce water use for livestock by 14%," Dall'erba says.

Dall'erba and co-author Andre Avelino performed a structural decomposition analysis, looking at 18 factors that drive U.S. water withdrawals across eight crops, six livestock categories, and 11 food manufacturing industries.

Based on data from Exiobase, a global supply-chain database, their analysis included water that's embedded into the production at all stages of the domestic and international supply chain, from crops and livestock to processed food production­ - highlighting the interconnectedness of global agribusiness.

For example, crops produced in the U.S. may rely on fertilizers produced in a different country. Similarly, soybeans produced in the U.S. could be used for food processing in China, or to feed livestock in Europe.

The current U.S.-China trade war is likely to affect these these supply-chain linkages, as Chinese import of oilseeds shifts to South America and Europe. The U.S. exported less soybean and pork to China over the last two years; therefore, less water was embedded into those exports. However, the next few years under a new U.S. administration may see an improvement in these relationships, Dall'erba notes.

The COVID-19 pandemic is also likely affecting water usage. Unemployment and economic crises have always impacted consumer demand, and international trade has sharply declined since the pandemic began. The 2008 recession resulted in decreased water usage and similar effects are expected in the current crisis, Dall'erba states.

Traditionally, scientists measuring the amount of water associated with production and the supply chain rely on a worldwide data set called the Water Footprint Network (WFN), which is based on a crop water-use model. However, Dall'erba and Avelino used data from the U.S. Geological Survey (USGS), which are based on observations rather than physical models.

"With the USGS data we find a decrease in the amount of water used, while the WFN data indicated a small increase. The difference is not large, but it's still a big deal, because you would find the wrong trend and reach misleading conclusions if you use the wrong data set," Dall'erba explains.

"This is important information for researchers. If you're in a situation where you have access to data based on observations rather than crop models, you should use those official data, especially because water saving policies are based on this dataset," he notes.

The questions addressed in this research are extremely relevant for any country that is heavy on agricultural production, Dall'erba says. "Namely, how can we feed the 10 billion people we expect to be at the global level by 2080, considering that we cannot necessarily expand the amount of land that's going to be used? And, given climate change, there is quite a lot of uncertainty with respect to the availability of water needed to grow crops and feed livestock in the years to come."

Water management strategies may include farm-level efforts such as increasing efficiency of the irrigation system, switching crops, and growing genetically modified crops.

Other measures may include policies aimed at affecting consumer behavior such as increasing taxes on water-intensive products and supporting ecolabeling, Dall'erba suggests.

Ecolabeling would require food manufacturing companies to report the amounts of water, carbon dioxide emissions, and labor associated with production. That could help consumers make informed choices and potentially shift consumption to less water-intensive products, he concludes.

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The article, "What Factors Drive the Changes in Water Withdrawals in the U.S. Agriculture and Food Manufacturing Industries between 1995 and 2010?" is published in Environmental Science and Technology. [doi.org/10.1021/acs.est.9b07071]

Authors are Sandy Dall'erba, Regional Economics Applications Laboratory, Department of Agricultural and Consumer Economics in the College of Agricultural, Consumer and Environmental Sciences, University of Illinois, and Andre Avelino, National Renewable Energy Laboratory.

The research was funded by a United States Department of Agriculture hatch grant.

Henderson island fossils reveal new Polynesian sandpiper species

CANTERBURY MUSEUM

Research News

 

IMAGE: THE EXTINCT KIRITIMATI SANDPIPER, PROSOBONIA CANCELLATA - A CLOSE COUSIN OF THE NEWLY DISCOVERED PROSOBONIA SAULI. view more 

CREDIT: ILLUSTRATION BY GEORGE EDWARD LODGE, 1907

Fossil bones collected in the early 1990s on Henderson Island, part of the Pitcairn Group, have revealed a new species of Polynesian sandpiper.

The Henderson Sandpiper, a small wading bird that has been extinct for centuries, is described in an article in the Zoological Journal of the Linnean Society published last week.

The newly-described bird is formally named Prosobonia sauli after Cook Islands-based ornithologist and conservationist Edward K Saul.

A team of researchers from New Zealand, Australia, Denmark, Switzerland, the Netherlands and China, led by Canterbury Museum Research Curator Natural History Dr Vanesa De Pietri, described the Henderson Sandpiper from 61 fossilised bones cared for by the Natural History Museum at Tring in England.

Canterbury Museum Visiting Researcher Dr Graham Wragg collected the bones from caves and overhangs on Henderson Island in 1991 and 1992 during the Sir Peter Scott Commemorative Expedition to the Pitcairn Islands.

Prosobonia sauli is the fifth known species of Polynesian sandpiper. All but one of the species, the endangered Tuamotu Sandpiper (Prosobonia parvirostris), are extinct.

"We think Prosobonia sauli probably went extinct soon after humans arrived on Henderson Island, which archaeologists estimate happened no earlier than the eleventh century," says Dr De Pietri.

"It's possible these humans brought with them the Polynesian rat, which Polynesian sandpiper populations are very vulnerable to."

DNA of the living Tuamotu Sandpiper and the extinct Tahiti Sandpiper (Prosobonia leucoptera), which is known only from a skin in the Naturalis Biodiversity Center in the Netherlands, was used to determine how Polynesian sandpipers are related to other wading birds.

"We found that Polynesian sandpipers are early-diverging members of a group that includes calidrine sandpipers and turnstones. They are unlike other sandpipers in that they are restricted to islands of the Pacific and do not migrate," says Dr De Pietri.

Comparisons with the other two extinct Polynesian sandpiper species, the Kiritimati Sandpiper (Prosobonia cancellata) and the Mo'orea Sandpiper (Prosobonia ellisi), are complicated. These birds are known only from illustrations primarily by William Wade Ellis, an artist and Surgeon's Mate on Captain James Cook's third expedition, who probably saw the birds alive in the 1770s.

Compared to the Tuamotu Sandpiper, its geographically closest cousin, the Henderson Sandpiper had longer legs and a wider, straighter bill, indicating how it foraged for food. It probably adapted to the habitats available on Henderson Island, which are different to those on other islands where Polynesian sandpipers were found.

Henderson Island is the largest island in the Pitcairn Group, in the middle of the South Pacific Ocean. It has been uninhabited since around the fifteenth century and was designated a World Heritage Site by the United Nations in 1988.

Dr Paul Scofield, Canterbury Museum Senior Curator Natural History and one of the study's co-authors, says Henderson Island is home to a number of unique species, a handful of which are landbirds like the Henderson Sandpiper.

"The island is really quite remarkable because every landbird species that lives there, or that we know used to live there, is not found anywhere else," he says.

Dr De Pietri says the study shows the need to protect the one remaining Polynesian sandpiper species, the Tuamotu Sandpiper.

"We know that just a few centuries ago there were at least five Polynesian sandpiper species scattered around the Pacific. Now there's only one, and its numbers are declining, so we need to ensure we look after the remaining populations."

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This research was supported by a grant from the Marsden Fund Council, managed by the Royal Society Te Apārangi, as well as the R S Allan Fund managed by Canterbury Museum.

CAPTION

The Henderson Island Sandpiper bones were excavated from caves during the Sir Peter Scott Commemorative Expedition in the early 1990s. Canterbury Museum Visiting Researcher Dr Graham Wragg, one of the paper's co-authors, is second from left in this photo.

Boosted signal

Novel analytic approach enhances nuclear magnetic resonance signal detection in previously 'invisible' regions

UNIVERSITY OF CALIFORNIA - SANTA BARBARA

Research News

 

First introduced into wide use in the middle of the 20th century, nuclear magnetic resonance (NMR) has since become an indispensable technique for examining materials down to their atoms, revealing molecular structure and other details without interfering with the material itself.

"It's a broadly used technique in chemical analysis, materials characterization, MRI -- situations in which you do a non-invasive analysis, but with atomic and molecular details," said UC Santa Barbara chemistry professor Songi Han. By placing a sample in a strong magnetic field and then probing it with radio waves scientists can determine from the response from the oscillating nuclei in the material's atoms the molecular structure of the material.

"However, the problem with NMR has been that because it's such a low-energy technique, it's not very sensitive," Han said. "It's very detailed, but you don't get much signal." As a result, large amounts of sample material may be needed relative to other techniques, and the signals' general weakness makes NMR less than ideal for studying complex chemical processes.

One remedy to this situation lies in dynamic nuclear polarization (DNP), a popular technique in which energy is "borrowed" from nearby electrons to enhance the signal emanating from the nuclei.

"Electrons have much higher energy than nuclei," Han explained. Built into specially-designed "radical" molecules, these unpaired electrons' polarization is transferred to the nuclei to improve their signal.

As hot a topic as DNP has become in the past decade, however, Han thinks we're still just scratching the surface.

"Despite DNP fundamentally changing the landscape of NMR, at the end of the day, only a handful of designer polarizing agents have been used," Han said. "A polarizing agent has been used to polarize hydrogen nuclei, but the power of DNP is greater than that. In principle, many other sources of electron spin can polarize many other types of nuclear spin."

In a paper published in the journal Chem, Han and colleagues push the boundaries of NMR with the first demonstration of dynamic nuclear polarization using the transition metal vanadium (IV). According to Han, their new approach -- dubbed "hyperfine DNP spectroscopy" -- offers a glimpse into the typically obscure local chemistry around transition metals, which are important for processes such as catalysis and reduction-oxidation reactions.

"Now we may be able to use endogenous metals that are present in catalysts and in many other important materials," Han said, without having to add polarizing agents -- those radical molecules -- to produce a stronger NMR signal.

The irony with transition metals such as vanadium and copper, Han explained, is that those atoms tend to tend to be functional centers -- places where important chemistry takes place.

"And those exact action centers and functional centers have been very difficult to analyze (with NMR) because they tend to become invisible," she said. The electron spins in the transition metal tend to shorten the lifetime of the NMR signal, she explained, making them disappear before they can be detected.

This wouldn't be the first time chemistry around transition metals has been observed, Han said, pointing to studies that looked at the chemical environments around gadolinium and manganese. But the commercially-available instrument used in those studies offered "a very narrow view."

"But there are many more metals that are much more important for chemistry," she said. "So we developed and optimized instrumentation that enhances the frequency range from the very narrow scope of a commercial instrument to a much broader range."

With their hyperfine DNP spectroscopy the researchers also found that the signal is indeed wiped out within a certain region around the metal called the spin diffusion barrier, but if the nuclei are located outside that zone the signal becomes visible.

"There are ways to lighten up that environment, but you need to know how and why," Han said, adding that the paper's co-lead authors, Sheetal Kumar Jain of UC Santa Barbara and Chung-Jui Yu of Northwestern University will continue to explore and apply this new method as they pursue their academic and research careers.

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Other contributors to the research on this paper include Christopher Blake Wilson and Tarnuma Tabassum of UC Santa Barbara; and Danna E. Freedman of Northwestern University.

Biochar from agricultural waste products can adsorb contaminants in wastewater

PENN STATE

Research News

 

UNIVERSITY PARK, Pa. -- Biochar -- a charcoal-like substance made primarily from agricultural waste products -- holds promise for removing emerging contaminants such as pharmaceuticals from treated wastewater.

That's the conclusion of a team of researchers that conducted a novel study that evaluated and compared the ability of biochar derived from two common leftover agricultural materials -- cotton gin waste and guayule bagasse -- to adsorb three common pharmaceutical compounds from an aqueous solution. In adsorption, one material, like a pharmaceutical compound, sticks to the surface of another, like the solid biochar particle. Conversely, in absorption, one material is taken internally into another; for example, a sponge absorbs water.

Guayule, a shrub that grows in the arid Southwest, provided the waste for one of the biochars tested in the research. More properly called Parthenium argentatum, it has been cultivated as a source of rubber and latex. The plant is chopped to the ground and its branches mashed up to extract the latex. The dry, pulpy, fibrous residue that remains after stalks are crushed to extract the latex is called bagasse.

The results are important, according to researcher Herschel Elliott, Penn State professor of agricultural and biological engineering, College of Agricultural Sciences, because they demonstrate the potential for biochar made from plentiful agricultural wastes -- that otherwise must be disposed of -- to serve as a low-cost additional treatment for reducing contaminants in treated wastewater used for irrigation.

"Most sewage treatment plants are currently not equipped to remove emerging contaminants such as pharmaceuticals, and if those toxic compounds can be removed by biochars, then wastewater can be recycled in irrigation systems," he said. "That beneficial reuse is critical in regions such as the U.S. Southwest, where a lack of water hinders crop production."

The pharmaceutical compounds used in the study to test whether the biochars would adsorb them from aqueous solution were: sulfapyridine, an antibacterial medication no longer prescribed for treatment of infections in humans but commonly used in veterinary medicine; docusate, widely used in medicines as a laxative and stool softener; and erythromycin, an antibiotic used to treat infections and acne.

The results, published today (Nov. 16) in Biochar, suggest biochars made from agricultural waste materials could act as effective adsorbents to remove pharmaceuticals from reclaimed water prior to irrigation. However, the biochar derived from cotton gin waste was much more efficient.

In the research, it adsorbed 98% of the docusate, 74% of the erythromycin and 70% of the sulfapyridine in aqueous solution. By comparison, the biochar derived from guayule bagasse adsorbed 50% of the docusate, 50% of the erythromycin and just 5% of the sulfapyridine.

The research revealed that a temperature increase, from about 650 to about 1,300 degrees F in the oxygen-free pyrolysis process used to convert the agricultural waste materials to biochars, resulted in a greatly enhanced capacity to adsorb the pharmaceutical compounds.

"The most innovative part about the research was the use of the guayule bagasse because there have been no previous studies on using that material to produce biochar for the removal of emerging contaminants," said lead researcher Marlene Ndoun, a doctoral student in Penn State's Department of Agricultural and Biological Engineering. "Same for cotton gin waste -- research has been done on potential ways to remove other contaminants, but this is the first study to use cotton gin waste specifically to remove pharmaceuticals from water."

For Ndoun, the research is more than theoretical. She said she wants to scale up the technology and make a difference in the world. Because cotton gin waste is widely available, even in the poorest regions, she believes it holds promise as a source of biochar to decontaminate water.

"I am originally from Cameroon, and the reason I'm even here is because I'm looking for ways to filter water in resource-limited communities, such as where I grew up," she said. "We think if this could be scaled up, it would be ideal for use in countries in sub-Saharan Africa, where people don't have access to sophisticated equipment to purify their water."

The next step, Ndoun explained, would be to develop a mixture of biochar material capable of adsorbing a wide range of contaminants from water.

"Beyond removing emerging contaminants such as pharmaceuticals, I am interested in blending biochar materials so that we have low-cost filters able to remove the typical contaminants we find in water, such as bacteria and organic matter," said Ndoun.

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Also involved in this research at Penn State were Heather Preisendanz, associate professor of agricultural and biological engineering, and Jack Watson, professor of soil science, soil physics and biogeochemistry; and Clinton Williams and Allan Knopf, scientists at the U.S. Department of Agriculture's Agricultural Research Service Arid Lands Agricultural Research Center, Maricopa, Arizona.

The U.S. Department of Agriculture's National Institute of Food and Agriculture and USDA's Agricultural Research Service supported this research.