Study offers insights into management of invasive paperbark trees

CAMBRIDGE UNIVERSITY PRESS

Research News

 

IMAGE:  "NEWLY RECRUITED MELALEUCA QUINQUENERVIA SEEDLINGS IN THE WESTERN EVERGLADES REGION OF FLORIDA, USA FOLLOWING A FIRE. PHOTO CREDIT: P. W. TIPPING view more 

CREDIT: PHOTO CREDIT: P. W. TIPPING.

WESTMINSTER, Colorado - March 10, 2021 - The paperbark tree (Melaleuca quinquenervia) was introduced to the U.S. from Australia in the 1900s. Unfortunately, it went on to become a weedy invader that has dominated natural landscapes across southern Florida, including the fragile wetlands of the Everglades.

According to an article in the journal Invasive Plant Science and Management (IPSM), one of the challenges in managing the paperbark species is its large seedbank. A single, large tree located within a dense stand can retain as many as 9 million viable seeds. The seeds are contained in capsules within the tree canopy and are released in response to disturbances, including wildfires and even the application of herbicides.

Researchers conducting a 13-year study of Florida paperbark populations say a biological control program launched by state and federal authorities has helped to slow the plant's invasive capacity. Now seedlings, saplings and large trees are continuously attacked by weevils, psyllids and galling flies.

After implementation of biological controls, there was a reduction of greater than 95 percent in the size of new populations of paperbark tree that emerged following wildfires. The biological controls have helped to reduce seedling and sapling density, slow their growth and inhibit surviving plants from achieving the capacity to reproduce for many years. One example: After a 1998 fire, the density of paperbark tree was reduced by 96.3 percent. By 2005, none of the remaining recruits had produced seed capsules.

Researchers say insights from Florida's experience can help other communities facing a paperbark invasion bring new focus to their control efforts.

"Our study shows biological controls help to suppress new growth, which can be left for a decade or more before any additional treatment is needed," said Philip Tipping, leader of the USDA-ARS Invasive Plant Research Laboratory in Davie, Florida. "As a result, land managers can prioritize removing large, reproductive trees instead of treating newly emerged populations."

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To learn more about effective controls for paperbark trees, you are invited to read the article "The influence of two wildfires and biological control agents on the population dynamics of Melaleuca quinquenervia in a seasonally inundated wetland", which appears in Volume 14, Issue 1 of IPSM. The article is currently available online.

About Invasive Plant Science and Management

Invasive Plant Science and Management is a journal of the Weed Science Society of America, a nonprofit scientific society focused on weeds and their impact on the environment. The publication focuses on invasive plant species. To learn more, visit http://www.wssa.net.

 New study links protein causing Alzheimer's disease with common sight loss

UNIVERSITY OF SOUTHAMPTON

Research News

 

Newly published research has revealed a close link between proteins associated with Alzheimer's disease and age-related sight loss. The findings could open the way to new treatments for patients with deteriorating vision and through this study, the scientists believe they could reduce the need for using animals in future research into blinding conditions.

Amyloid beta (AB) proteins are the primary driver of Alzheimer's disease but also begin to collect in the retina as people get older. Donor eyes from patients who suffered from age-related macular degeneration (AMD), the most common cause of blindness amongst adults in the UK, have been shown to contain high levels of AB in their retinas.

This new study, published in the journal Cells, builds on previous research which shows that AB collects around a cell layer called the retinal pigment epithelium (RPE), to establish what damage these toxic proteins cause RPE cells.

The research team exposed RPE cells of normal mouse eyes and in culture to AB. The mouse model enabled the team to look at the effect the protein has in living eye tissue, using non-invasive imaging techniques that are used in ophthalmology clinics. Their findings showed that the mouse eyes developed retinal pathology that was strikingly similar to AMD in humans.

Dr Arjuna Ratnayaka, a Lecturer in Vision Sciences at the University of Southampton, who led the study said, "This was an important study which also showed that mouse numbers used for experiments of this kind can be significantly reduced in the future. We were able to develop a robust model to study AMD-like retinal pathology driven by AB without using transgenic animals, which are often used by researchers the field. Transgenic or genetically engineered mice can take up to a year and typically longer, before AB causes pathology in the retina, which we can achieve within two weeks. This reduces the need to develop more transgenic models and improves animal welfare."

The investigators also used the cell models, which further reduced the use of mice in these experiments, to show that the toxic AB proteins entered RPE cells and rapidly collected in lysosomes, the waste disposal system for the cells. Whilst the cells performed their usual function of increasing enzymes within lysosomes to breakdown this unwanted cargo, the study found that around 85% of AB still remained within lysosomes, meaning that over time the toxic molecules would continue to accumulate inside RPE cells.

Furthermore, the researchers discovered that once lysosomes had been invaded by AB, around 20 percent fewer lysosomes were available to breakdown photoreceptor outer segments, a role they routinely perform as part of the daily visual cycle.

Dr Ratnayaka added, "This is a further indication of how cells in the eye can deteriorate over time because of these toxic molecules collecting inside RPE cells. This could be a new pathway that no-one has explored before. Our discoveries have also strengthened the link between diseases of the eye and the brain. The eye is part of the brain and we have shown how AB which is known to drive major neurological conditions such as Alzheimer's disease can also causes significant damage to cells in retina."

The researchers hope that one of the next steps could be for anti-amyloid beta drugs, previously trialled in Alzheimer's patients, to be re-purposed and trialled as a possible treatment for age-related macular degeneration. As the regulators in the USA and the European Union have already given approval for many of these drugs, this is an area that could be explored relatively quickly.

The study may also help wider efforts to largely by-pass the use of animal experimentation where possible, so some aspects of testing new clinical treatments can transition directly from cell models to patients.

This research was funded by the National Centre for the Replacement Refinement & Reduction of animals in research (NC3Rs). Dr Katie Bates, Head of Research Funding at the NC3Rs said:

"This is an impactful study that demonstrates the scientific, practical and 3Rs benefits to studying AMD-like retinal pathology in vitro."

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Animal studies were overseen by the institutions' Ethical Research Committee and carried out in accordance with the UK Animal (Scientific Procedures) Act of 1986. Experiments also conformed to the ARVO statement for the Use of Animals in Ophthalmic and Vision Research. The experimental protocol was approved by the University of Southampton Research Ethics Committee and work carried out under the UK Home Office project licence #P395C9E5F (licence approval date: 4 July 2016).

 

Are 'bacterial probiotics' a game-changer for the biofuels industry?

TECHNICAL UNIVERSITY OF DENMARK

Research News

 

IMAGE: BRAZIL'S TOTAL ETHANOL PRODUCTION IN 2019 WAS 34.5 BILLION LITERS WITH DOMESTIC DEMAND FOR 34 BILLION LITERS MAKING THE COUNTRY THE HOME TO THE LARGEST FLEET OF CARS THAT... view more 

CREDIT: THE NOVO NORDISK FOUNDATION CENTER FOR BIOSUSTAINABILITY

In a study recently published in Nature Communications, scientists from The Novo Nordisk Foundation Center for Biosustainability (DTU) and Yale University have investigated how bacteria that are commonly found in sugarcane ethanol fermentation affect the industrial process. By closely studying the interactions between yeast and bacteria, it is suggested that the industry could improve both its total yield and the cost of the fermentation processes by paying more attention to the diversity of the microbial communities and choosing between good and bad bacteria.

The scientists dissected yeast-bacteria interactions in sugarcane ethanol fermentation by reconstituting every possible combination of the microbial community structure, covering approximately 80% of the biodiversity found in industrial processes, and especially one bacterium deserves extra attention: Lactobacillus amylovorus. But how come exactly this one doesn't fall into the category of "the bad guys"? The main reason is that it produces a lot of the molecule acetaldehyde, which is used to feed yeast and thus helps it to grow. You could say that Lactobacillus amylovorus is more generous by nature and shares the meal, whereas many other bacteria involved in these processes prefer simply to steal the food.

"It works almost in the same way as a probiotic that shields the bad bacteria from entering into the system. And when this bacterium grows, it will grow in a way that is almost symbiotic with the yeast which is very beneficial for the industrial process", says Felipe Lino, former PhD Student at The Novo Nordisk Foundation Center for Biosustainability and Global R & D Manager at Anheuser-Busch InBev.

Significant improvement of yield

Thus, companies could take advantage of selecting not only for an ideal yeast strain for production, as they started doing already in the 90's, but to select for the best-suited bacteria as well, since it is completely impossible to get rid of bacteria that are hanging around no matter what. An effort that could turn out to pay dividends already in a short-term perspective.

By using this probiotic in a sugarcane ethanol fermentation, it is estimated that the fermentation yield could increase by three percent. While three percent can sound like a rather low number this is definitely not the case. According to Brazil's Biofuels Annual 2019, Brazil's total ethanol production in 2019 was 34.5 billion liters with domestic demand for 34 billion liters making the country the home to the largest fleet of cars that use ethanol derived from sugarcane as an alternative fuel to fossil fuel-based petroleum.

These numbers indicate that optimised fermentation processes hold great potential. One way to start ensuring more efficient industrial production of ethanol would be to apply more targeted approaches and shift away from a "one-size fits all" strategy where sulfuric acid treatment is used without further consideration to lower the pH and kill the bacteria to keep the population under a certain threshold. This would be beneficial both economically and environmentally, says Morten Sommer, Professor and Group Leader at The Novo Nordisk Foundation Center for Biosustainability.

"Instead of using a broad range of antibiotics, one should go for a more specific solution where you keep the good bacteria inside the fermenter. This is definitely a paradigm shift because you are not per definition fighting against all bacteria, since some of the bacteria are actually good and improve your final output significantly while also having a positive effect on production costs and the environmental footprint."

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UH OH

Variant B.1.1.7 of COVID-19 associated with a significantly higher mortality rate

UNIVERSITY OF EXETER

Research News

 

Variant B.1.1.7 of COVID-19 associated with a significantly higher mortality rate, research shows

The highly infectious variant of COVID-19 discovered in Kent, which swept across the UK last year before spreading worldwide, is between 30 and 100 per cent more deadly than previous strains, new analysis has shown.

A pivotal study, by epidemiologists from the Universities of Exeter and Bristol, has shown that the SARS-CoV-2 variant, B.1.1.7, is associated with a significantly higher mortality rate amongst adults diagnosed in the community compared to previously circulating strains.

The study compared death rates among people infected with the new variant and those infected with other strains.

It showed that the new variant led to 227 deaths in a sample of 54906 patients - compared to 141 amongst the same number of closely matched patients who had the previous strains.

With the new variant already detected in more than 50 countries worldwide, the analysis provides crucial information to governments and health officials to help prevent its spread.

The study is published in the British Medical Journal on Wednesday, 10 March 2021.

Robert Challen, lead author of the study from the University of Exeter said: "In the community, death from COVID-19 is still a rare event, but the B.1.1.7 variant raises the risk. Coupled with its ability to spread rapidly this makes B.1.1.7 a threat that should be taken seriously."

The Kent variant, first detected in the UK in September 2020, has been identified as being significantly quicker and easier to spread, and was behind the introduction of new lockdown rules across the UK from January.

The study shows that the higher transmissibility of the Kent strain meant that more people who would have previously been considered low risk were hospitalised with the newer variant.

Having analysed data from 54609 matched pairs of patients of all age-groups and demographics, and differing only in strain detected, the team found that there were 227 deaths attributed to the new strain, compared to 141 attributable to earlier strains.

Leon Danon, senior author of the study from the University of Bristol said: "We focussed our analysis on cases that occurred between November 2020 and January 2021, when both the old variants and the new variant were present in the UK. This meant we were able to maximise the number of "matches" and reduce the impact of other biases. Subsequent analyses have confirmed our results.

"SARS-CoV-2 appears able to mutate quickly, and there is a real concern that other variants will arise with resistance to rapidly rolled out vaccines. Monitoring for new variants as they arise, measuring their characteristics and acting appropriately needs to be a key part of the public health response in the future."

Ellen Brooks-Pollock from the University of Bristol expanded: "It was fortunate the mutation happened in a part of the genome covered by routine testing. Future mutations could arise and spread unchecked".

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Reflecting on your own capabilities boosts resilience

UNIVERSITY OF ZURICH

Research News

 

The unpredictable nature of life during the coronavirus pandemic is particularly challenging for many people. Not everyone can cope equally well with the uncertainty and loss of control. Research has shown that while a large segment of the population turns out to be resilient in times of stress and potentially traumatic events, others are less robust and develop stress-related illnesses. Events that some people experience as draining seem to be a source of motivation and creativity for others.

These differing degrees of resilience demonstrate that people recover from stressful events at different rates, with psychosocial factors such as positivity, optimism, the ability to self-regulate, social skills, problem-solving skills and social support playing a role. A team from the Department of Psychology and the University Hospital of Psychiatry Zurich teamed up with researchers from New York to investigate how people can strengthen their psychological resilience when facing adversity.

Importance of believing in your own power

"Self-efficacy is a key element of resilience," explains Birgit Kleim, professor of psychology at UZH and director of the study. "By self-efficacy, I mean the belief that we have the ability to influence things to at least a small degree, even if some things are unchangeable." A self-efficacious person is convinced that they can draw on their own powers to overcome difficult and challenging situations. It doesn't matter whether this is actually the case, as Kleim explains: "Without believing in your own capabilities, you wouldn't take on any challenges in the first place." Self-efficacious people have stronger problem-solving abilities and a higher level of persistence. They also show changes in brain activation in regions linked to emotional regulation.

How might it be possible, then, to boost people's self-efficacy so that they can harness its positive powers in the coronavirus era? For the resilience study, a team of researchers examined 75 people who were distressed by a negative emotional memory. Before recalling and reassessing this distressing memory, one group of subjects was instructed to vividly recall a positive event such as a beautiful experience in nature or a joyful encounter with others. The others were instructed to think of a time in which they felt they were particularly self-efficacious: situations such as having a successful conversation, passing a difficult exam or giving a presentation. In many cases, doing this exercise just once was already enough to achieve a positive effect.

Recalling autobiographical self-efficacy yields dramatic effects

"Recalling a specific instance of one's own self-efficacy proved to have a far greater impact than recalling a positive event," says Kleim. People who actively recalled their own self-efficacious behavior found it easier to reassess a negative situation and view it in a different light. They perceived the negative experience as less distressing than the subjects who were instructed to reflect on a positive memory unconnected to self-efficacy.

"Our study shows that recalling self-efficacious autobiographical events can be used as a tool both in everyday life and in clinical settings to boost personal resilience," explains the research team. It may be possible to strategically use memories of overcoming past challenges as a way of coping with crisis situations. This also applies to the coronavirus crisis, where these memories can be used to shield against the negative impacts of the pandemic.

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Air pollutant reductions could enhance global warming without greenhouse gas cuts

Modeling predicts that loss of cooling effect attributed to sulfate aerosols will increase surface air temperature if air pollution and carbon dioxide are not simultaneously reduced

KYUSHU UNIVERSITY

Research News

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IMAGE: SIMULATIONS USING MIROC-SPRINTARS PREDICT ANNUAL MEAN DISTRIBUTION OF CHANGES IN SURFACE AIR TEMPERATURE FOLLOWING REDUCTION OF SO2 EMISSIONS FROM FUEL SOURCES TO 10% OF THE CURRENT LEVEL UNDER PRESENT (LEFT)... view more 

CREDIT: TOSHIHIKO TAKEMURA, KYUSHU UNIVERSITY

As countries around the world race to mitigate global warming by limiting carbon dioxide emissions, an unlikely source could be making climate goals harder to achieve without even deeper cuts in greenhouse gas production: reductions in air pollution.

New modeling experiments from Kyushu University in Japan of the long-term effects of reductions in pollutants known as sulfate aerosols predicts further increases in surface air temperature at current and increased carbon dioxide levels because of the loss of an overall cooling effect caused by the light-scattering particles.

"Air pollution causes an estimated seven million premature deaths per year worldwide, so action is essential, especially in emerging and developing countries, which tend to be most affected," says Toshihiko Takemura, professor at Kyushu University's Research Institute for Applied Mechanics and author of the study.

"However, reductions in air pollutants must come hand in hand with reductions in greenhouse gases to avoid accelerating global warming."

To analyze how sulfate aerosols--small particles of sulfur-containing compounds often produced by burning fossil fuels or biomass--influence climate, Takemura used a combination of models known as MIROC-SPRINTARS.

MIROC is a general circulation model taking into account many key aspects of the atmosphere and oceans along with their interactions, while SPRINTARS, which is widely used by news outlets for air pollution forecasts, is capable of predicting the mixing of aerosols in the atmosphere.

Combining the two models allows for effects such as the scattering and absorption of light by aerosols and the interaction of aerosols with clouds to be included in the climate projection.

Looking at the immediate changes to the atmosphere in the case of reduced emission of SO2--a precursor of sulfate aerosols--from fuel sources, Takemura found that changes such as in light scattering and cloud formation by the sulfate aerosols lead to more energy overall entering the atmosphere, though the increase is similar regardless of whether the atmospheric carbon dioxide concentration is the same as present levels or doubled.

However, considering changes in the climate and surface temperatures over longer time scales showed that not only does the surface air temperature increase with a reduction in sulfate aerosols but this increase is even larger when carbon dioxide levels double.

"Although the fast response is similar for both situations, long-term changes caused by more slowly responding factors related to interactions with the oceans and subsequent changes, such as in clouds and precipitation, eventually leads to a bigger temperature increase," explains Takemura.

"Thus, global warming will accelerate unless increases in greenhouse gas concentrations are suppressed as air pollution control measures decrease sulfate aerosol concentrations, further emphasizing the urgency for reducing carbon dioxide in the atmosphere," he concludes.

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For more information about this research, see "Return to different climate states by reducing sulphate aerosols under future CO2 concentrations," Toshihiko Takemura, Scientific Reports (2020). https://doi.org/10.1038/s41598-020-78805-1

Fossil lamprey larvae overturn textbook assumptions on vertebrate origins

Study shows studies of the origin of vertebrates - including human - were based on incorrect assumptions since the late 1800s

UNIVERSITY OF THE WITWATERSRAND

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IMAGE: 1.5 CM LONG PRISCOMYZON HATCHLING SHOWING BULGE OF YOLK SAC MATERIAL. PHOTO AT LEFT, ANNOTATED PHOTO AT CENTRE AND DRAWING AT RIGHT. FIGURE FROM PAPER. PICTURE CREDIT NATURE PUBLISHING GROUP.... view more 

CREDIT: NATURE PUBLISHING GROUP

The unprecedented discovery of an ancient lamprey growth series, published in the prestigious scientific journal, Nature, is overturning long-held ideas as to what modern lampreys may tell us about the origin of vertebrates (all animals with a backbone such as goldfish, lizards, crows and people).

"Lampreys and modern hagfish are the only jawless fish alive that branched off from the family tree of vertebrates before they got jaws," says Dr Rob Gess from the Albany Museum in Makhanda, who discovered the ancient fossils. "This makes them very interesting for researchers attempting to understand the earliest stages of vertebrate history."

Until now, it was commonly believed that modern lampreys were swimming time capsules that could give unique insights into the biology and genome (DNA) of a truly ancient lineage.

This belief was supported by the discovery, published in Nature in 2006, of an exquisitely preserved lamprey fossil (Priscomyzon) at the 360-million-year-old Waterloo Farm black shales near Makhanda/Grahamstown, South Africa. The discovery was met with excitement worldwide as it was the oldest lamprey ever found, yet it appeared to have been essentially almost identical to modern adult lampreys. Modern lampreys are bizarre fish, eel-like in shape, that feed by latching onto other fish with a sucker around their mouth, securing their grip with circles of teeth and then drinking their victim's blood after rasping a hole with special teeth on their tongue. Therefore, adult lampreys are clearly successful, having arisen before the first four-legged-animals moved onto land and survived, with little change, ever since.

In many ways, modern lampreys indeed provide unique insights into their ancient ancestry. But new evidence shows that this is not the case when it comes to the juvenile larval stage.

Since the 19th century, biologists have treated the larvae/juveniles of modern lampreys as a relic of deep evolutionary ancestry. These blind, filter-feeding, worm-like larvae (ammocoetes) burrow in stream beds and filter water for minute food particles before slowly transforming into free-swimming, eyed, actively feeding adults. Crucially, this strange life history was thought to echo transformations some 500 million years ago, which gave rise to all fish lineages, including the one that ultimately led to humans. Hence, the last invertebrate ancestor of vertebrates is often portrayed as ammocoete-like, and the earliest vertebrate as being lamprey-like. But for this to be a reasonable model, both ammocoetes and lampreys would need to hark back to the dawn of our (vertebrate) history.

However, the new fossil discoveries contradict the conventional wisdom that our long chain of ancestors ever included a lamprey-larva-like fish. Painstaking excavation of shale samples from Waterloo Farm has revealed a growth series of Priscomyzon illustrating its development from hatchling to adult. Remarkably, the smallest preserved individuals, barely 15mm in length, still carried a yolk sac, signalling that these had only just hatched before entering the fossil record.

Of crucial importance: even the hatchlings were already sighted with large eyes and armed with a toothed sucker, much like the blood-sucking adult phase of modern lampreys, and completely unlike their modern larval counterparts. This drastically different structure of ancient lamprey infants provides evidence that modern lamprey larvae are not evolutionary relics. Instead, the modern filter-feeding phase is a more recent innovation that allowed lampreys to populate and thrive in rivers and lakes. A less complete (previously unpublished) partial growth series of three types of slightly younger lampreys from North America support the finding. Therefore, distant human ancestry seemingly did not include a lamprey-larva-like stage. Modern lampreys now appear to be a highly evolved side branch, which shared a common ancestor with us - probably a jawless fish enclosed in bony armour.

Truly a new entry for the textbooks.

CAPTION

This reconstruction of the Late Devonian estuarine lake at Waterloo Farm (near Makhanda, South Africa) captures the life history of a stem lamprey Priscomyzon riniensis. Three individuals representing different ontogenetic stages take a shelter in the meadow of charophyte algae Octochara crassa. Clockwise from right: a yolk-sac-carrying hatchling tucked in the charophyte; a juvenile attached to the substrate in the foreground, and an adult looming over the other individuals and showing its feeding apparatus. In the background, a school of the coelacanth Serenichthys kowiensis swim by.

CREDIT

Kristen Tietjen

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Dr Robert Gess and Dr Tetsuto Miyashita discussing Priscomyzon specimens.

CREDIT

Todani Funyufunyu

Cereal side streams can be utilized as sources of protein and dietary fiber

UNIVERSITY OF HELSINKI

Research News

 

Every year, the food industry generates substantial amounts of side streams, such as cereal brans. Instead of using them for food, they are primarily utilised as feed or in energy production.

"We are wasting high-quality protein and dietary fibre. Using brans in food production would improve resource sufficiency, and they would be viable for healthy diets," says Pia Silventoinen, who recently defended her doctoral thesis at the Faculty of Agriculture and Forestry, University of Helsinki, Finland.

However, the performance of plant-based ingredients, proteins in particular, is often poorer in food applications compared with their animal-derived counterparts. Silventoinen developed in her doctoral research project, carried out at VTT Technical Research Centre of Finland, techniques for producing protein-rich, nutritionally balanced and highly functional raw materials targeted for beverages and spoonable products from cereal side streams - wheat, rice and rye brans as well as barley endosperm fraction.

In her doctoral thesis, Silventoinen optimised sustainable and environmentally friendly dry separation techniques, including dry milling and air classification. They were used to produce protein- and dietary fibre-rich hybrid ingredients, functional properties of which exceeded those of the raw material side streams. Moreover, these properties could be further improved through enzymatic and ultrasound treatment.

"Enzyme-treated protein-rich rice bran fraction could be used as a raw material, for example, inspoonable food products which deliver protein to consumers. It also contains so high amount of dietary fibre that a nutritional claim 'source of fibre' could be displayed on the packaging. Similarly, ultrasound-treated barley protein ingredients could be applied in the production of plant-based milk substitutes," Silventoinen envisions.

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https://helda.helsinki.fi/handle/10138/326182

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Researchers solve more of the mystery of Laos megalithic jars

'Plain of Jars' dates put at 1240 to 660 BCE

UNIVERSITY OF MELBOURNE

Research News

 

IMAGE: DR SHEWAN AND COLLABORATORS PRESENT NEW RADIOCARBON RESULTS FOR SITE USE AND ALSO INTRODUCE GEOCHRONOLOGICAL DATA DETERMINING THE LIKELY QUARRY SOURCE FOR ONE OF THE LARGEST MEGALITHIC SITES. view more 

CREDIT: PLAIN OF JARS ARCHAEOLOGICAL RESEARCH PROJECT

New research conducted at the UNESCO World Heritage listed 'Plain of Jars' in Laos has established the stone jars were likely placed in their final resting position from as early as 1240 to 660 BCE.

Sediment samples from beneath stone jars from two of the more than 120 recorded megalithic sites were obtained by a team led Dr Louise Shewan from the University of Melbourne, Associate Professor Dougald O'Reilly from the Australian National University (ANU) and Dr Thonglith Luangkoth from the Lao Department of Heritage.

The samples were analysed using a technique called Optically Stimulated Luminescence (OSL) to determine when sediment grains were last exposed to sunlight.

"With these new data and radiocarbon dates obtained for skeletal material and charcoal from other burial contexts, we now know that these sites have maintained enduring ritual significance from the period of their initial jar placement into historic times," Dr Shewan said.

The megalithic jar sites in Northern Laos comprise one to three-metre-tall carved stone jars, weighing up to 20 tonnes, dotted across the landscape, appearing alone or in groups of up to several hundred.

Dr Shewan and her team completed their most recent excavations in March 2020, revisiting Site 1 (Ban Hai Hin), and arriving back in Australia just before global pandemic international boarder closures.

Site 1 revealed more burials placed around the jars and confirmed earlier observations that the exotic boulders distributed across the site are markers for ceramic burial jars buried below.

Published today in PLOS One, Dr Shewan and collaborators present new radiocarbon results for site use and also introduce geochronological data determining the likely quarry source for one of the largest megalithic sites.

While geologists have used detrital zircon U-Pb dating for several decades, this methodology has recently been used to establish the provenance of ceramic and stone sources in archaeological contexts including Stonehenge.

Conducted at ANU by Associate Professor Richard Armstrong, the U-Pb zircon ages measured in jar samples from Site 1 were compared to potential source material, including a sandstone outcrop and an incomplete jar from a presumed quarry located some 8km away. The zircon age distributions revealed very similar provenance suggesting that this outcrop was the likely source of the material used for the creation of jars at the site.

"How the jars were moved from the quarry to the site, however, remains a mystery," Associate Professor O'Reilly said.

The next challenge for the researchers is to obtain further samples from other sites and from across the geographic expanse of this megalithic culture to understand more about these enigmatic sites and the period over which they were created.

Dr Shewan said this is not an especially easy task given the extensive unexploded ordnance (UXO) contamination in the region where less than 10 per cent of the known jar sites have been cleared.

"We expect that this complex process will eventually help us share more insights into what is one of Southeast Asia's most mysterious archaeological cultures."

The full team of researchers includes La Trobe University, James Cook University, University of Gloucestershire and international collaborators from Laos, New Zealand and Hong Kong.

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Framed by gender: Women artists erased from peak prices, sales at art auctions

MONASH UNIVERSITY

Research News

IMAGE: ARTWORK PRODUCED BY FEMALE ARTISTS COMPRISE LESS THAN 4 PER CENT OF ART AUCTION SALES, DESPITE A NEAR EQUAL SHARE OF WOMEN AND MEN PURSUING DEGREES IN FINE ARTS, NEW... view more 

CREDIT: MONASH UNIVERSITY

They say a picture is worth a thousand words. However, many women artists - and the stories their works tell - comprise less than 4 per cent of total art sold at auction and fail to attract high selling prices compared to male artists.

A world-first international study by researchers at Monash University, Maastricht University (The Netherlands) and Artnet Worldwide, based in New York City, found that a staggering 96.1 per cent (2,572,346) of all artworks sold at auctions worldwide between 2000 and 2017 are attributed to male artists.

However, work by female artists are on average 4.4 per cent more expensive after controlling for artwork and transaction characteristics. This factor contributes to higher barriers for women to enter the art market, researchers say.

Despite commanding a higher average price for their work, women artists are almost exclusively absent from the top echelons of the total value of art sold at auction. Forty-two men occupy the top 0.03 per cent of the market, where 40 per cent of the sales value is concentrated. Just one woman artist, Joan Mitchell, cracks the top 50.

Findings of this study were published in the Journal of Cultural Economics.

Dr Marina Gertsberg, Lecturer in Banking & Finance in the Monash Business School and co-author of the study, said even with a near equal share of women and men pursuing fine art degrees, women find it more difficult to turn that interest into saleable artwork.

"Women might feel discouraged by their market prospects at the very top, or they might experience discrimination by dealers and buyers who ascribe higher potential to men at the very top. Increasing the visibility of female artists and giving them the chance to compete early on in their careers is therefore most important in improving female representation," Dr Gertsberg said.

"There is currently some movement in this direction. Museums and galleries are increasing the share of female artists on display. This helps buyers to be acquainted with female art and gain more confidence in it."

At the same time, Dr Gertsberg says it is important not to segregate female and male artists.

"For example, 'women-only' exhibits do not allow the audience to compare artworks by males and females and pushes female art to a niche category. Women should be given the chance to compete side-by-side with men," she said.

"The fact that the auction prices are higher for artwork by women than artwork by men, after accounting for artwork style and other characteristics that affect prices, shows that women can compete in the market when given the chance."

This investigation considered the prices paid at auction for artworks created by male and female artists based on birth-identified sex, and how these prices have evolved over time.

Their dataset comprised almost the full population of global art auction transactions from 2000 to 2017, covering more than 1800 auction houses.

In the top echelon of the art market - for sales of greater than $1 million - artworks by male artists sell for 18.4 per cent more than those by female artists. The top 40 artists, consisting solely of men, represent 40 per cent of total market share. Artworks by female artists represent just 3-5 per cent of major permanent collections in the USA and Europe.

While there are about 110,938 male artists with work on display and up for auction at major galleries, there are only 5612 female artists present. The proportion of female artists is highest for contemporary art (9.3 per cent) and the least for artwork from the 'old masters' period (2.9 per cent).

Dr Gertsberg said the career trajectories of female and male artists are likely to diverge very early, and in order to formulate policy, it is important to identify when female artists encounter barriers that forces them to drop out of the profession.

"The fact that we observe higher median prices for female artists indicates that buyers perceive quality of artworks by female artists as overall better than the artworks of male artists. We would not expect this difference in quality if men and women faced the same difficulty in entering the market," Dr Gertsberg said.

"It might seem counterintuitive, but we would like to see the average price for artworks produced by women fall to the level of men. This would imply that the quality of male and female artists is similar and suggest that the playing field is truly equal."

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This study was a collaboration involving Dr Marina Gertsberg (Monash Business School), Fabian Bocart (Artnet Worldwide Corporation) and Rachel Pownall (Maastricht University). To download a copy of the research paper, please visit https://doi.org/10.1007/s10824-020-09403-2