Wednesday, August 14, 2024

Crook croc Cuisine: Could a bad dinner save a species?

Scientists cook up a plan to save freshwater crocodiles from toxic cane toads

Macquarie University

image:
Freshwater crocodile taking doctored cane toad bait
Photo: Georgia Ward-Fear
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Credit: Georgia Ward-Fear

Scientists from Macquarie University working with Bunuba Indigenous rangers and the Department of Biodiversity, Conservation and Attractions (DBCA) in Western Australia have trialled a new way to protect freshwater crocodiles from deadly invasive cane toads spreading across northern Australia.

Freshwater crocodiles (Crocodylus johnstoni) are a culturally significant animal and part of traditional owners’ Dreamtime stories in the region. The loss of these predators also upsets the delicate balance of local ecosystems.

The group’s research, published in Proceedings of the Royal Society: B on August 14, shows a method to significantly reduce freshwater crocodile death rates in areas where cane toads first invade by teaching the crocodiles to link cane toads with a bout of food poisoning.

Lead author Dr Georgia Ward-Fear from Macquarie University’s School of Natural Sciences and her co-author, Professor Rick Shine, documented the successful trial of a behavioural ecology method called conditioned taste aversion (CTA).

Bunuba ranger coordinator Paul Bin Busu and rangers Kristen Andrews and Karl Bin Busu reported noticeable changes in crocodile behaviours during the program.

Following the successful conservation intervention, Sara McAllister from DBCA’s state cane toad program can plan future interventions in areas with similar ecology.

Trail of destruction

Since cane toads were imported from South America in the 1930s, they have left a trail of native animal casualties across northern Australia, wiping out local predator species such as goannas, snakes and freshwater crocodiles.

These animals are important foods for traditional owners and play a vital role in their environments – but have no innate defence from the poisonous toads.

“Losing freshwater crocodiles to cane toads will mean that bottom feeders in our rivers will eat all the bait such as judembah (cherrabin, a large freshwater prawn) and lardy (boney bream, an estuarine fish), leaving no fish for the barramundi and stingray to eat,” says Ranger coordinator Paul Bin Busu.

The study took place mainly in May to October – the dry season in Australia’s tropical north, when river systems can shrivel into a series of isolated pools, supporting far fewer of the prawns, fish and amphibians making up a freshwater crocodile’s normal aquatic diet, yet higher densities of the crocodiles

“Freshwater crocs can be heavily impacted astheir river systems dry out during the late dry season,” says Dr Ward-Fear. “They end up congregating in large numbers with very little food, and as toads begin to use these waterbodies for rehydration, the two come into contact and we see large numbers of crocodile deaths over a few months.”

How they did it

Between 2019 and 2022, Dr Ward-Fear and Professor Shine worked with local rangers and DBCA staff to deploy doctored cane toad carcasses across four large gorge systems in the Kimberley region of north-western Australia.

Bunuba and DBCA collected hundreds of cane toads, removing the poisonous parts and injecting the toad bodies with enough of a nausea-inducing chemical that freshwater crocodiles eating the bait would feel temporarily sick (but wouldn’t die).

Control baits of chicken meat – with no nausea-inducing additives – were used to monitor the effectiveness of conditioned taste aversion training.

“Being a part of the program on the ground doing the job was really good,” says Paul Bin Busu, whose team of rangers set up hundreds of bait stations over the river banks, using canoes to hang and replace fresh baits and monitor the responses of crocodiles

Getting Results

“The first three days we noticed the crocodiles were taking the cane toads then they would go away.. Then we noticed they would smell the cane toad before eating, and on the lastday we noticed that it was mostly the chicken necks getting eaten,” he says.

Using nocturnal ‘spotlighting’ surveys and remotely triggered wildlife cameras to monitor crocodile and toad numbers, the team found areas where taste aversion trials took place had greatly-reduced crocodile mortality rates compared to unbaited control sites.

“Our baiting completely prevented deaths in areas where cane toads were arriving and decreased deaths by 95% in areas where toads had been for a couple of years. Effects which continued in the years following.” said Dr. Ward-Fear.

“These are really exciting results because it provides land managers with tools to use ahead of the invasion, but also behind the invasion front” says Sara McAllister from DBCA. “Together we’ve shown that collaborations between academics, indigenous rangers and land management agencies can be really effective for conservation science”

“After the program we see that the populations of the crocodiles are coming back, which is a good thing to see,” says Paul Bin Busu.

The team has previously used a similar technique, this time with less-toxic small cane toads, to protect yellow monitor lizards from the invasive predators.

Senior author Professor Rick Shine says the study details the successful use of conditioned taste aversion as a behavioural ecology technique.

“At a time when globalisation has massively increased the spread of invasive species, behavioural ecology can protect vulnerable ecosystems,” Professor Shine says.

END

Taste-aversion training to pro [VIDEO] |

Credit

Cane Toad Alliance

Funding:

This research was funded by the Australian Research Council (LP170100013)
The Cane Toad Coalition is funded by:
WA Department of Biodiversity Conservation and Attractions (DBCA), Australian Wildlife Conservancy, World Wide Fund for Nature Australia, Kimberley Land Council, Rangelands Natural Resource Management, Dunkeld Pastoral and Matsos Brewery.

Journal

Proceedings of the Royal Society B Biological Sciences

DOI

10.1098/rspb.2023.2507

Method of Research

Experimental study

Subject of Research

Animals

Article Title

Taste aversion training can educate free-ranging crocodiles against toxic invaders

Article Publication Date

13-Aug-2024

Chromatin structure plays a key role in canine social behavior evolution

Both the linear sequence of DNA and its three-dimensional configuration are linked to friendly behavior shaped by dog domestication, providing new insights into the molecular mechanisms underlying social traits

Eötvös Loránd University

Friendly dog listens — image:
Canine hyper-sociability structural variants associated with altered three-dimensional chromatin state
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Credit: Photo: Vanda Molnár

A new study on dogs found that chromatin's spatial structure has a significant role in the evolution of social behavior. Chromatin, the compact form of DNA, not only packages genetic material but also plays a crucial role in gene regulation. This study demonstrates that both the linear sequence of DNA and its three-dimensional configuration are linked to friendly behavior shaped by dog domestication, providing new insights into the molecular mechanisms underlying social traits.

Behavioral traits such as sociability are influenced by numerous genes, their interactions, environmental factors, and individual life experiences.

Because the effect of a single gene is difficult to detect, it made headlines when in 2017, Dr. Bridgett vonHoldt, a professor at Princeton University, and her team identified specific elements in the GTF2I gene in dogs, linked to Williams-Beuren syndrome (WB) in humans, characterized by hypersociability, extreme friendliness, and craniofacial abnormalities. The findings suggested that

the selection for increased friendliness in dogs involved changes in the GTF2I gene.

"This gene plays a role in neural development and pathways related to anxiety and sociability and is likely a key determinant of the friendly behavior shaped by domestication. In our current study, we aimed to investigate how genetic variants influence the 3D structure of the DNA containing this gene," says vonHoldt, lead author of the publication in BMC Genomics. "The GTF2I gene has several variants, with the ancient, wolf-like variant found in three out of ten individuals. We were curious about how the ancient and more modern variants precisely affect gene function." The gene variants originate from retrotransposons, which are mobile, self-multiplying DNA elements.

The researchers examined an intronic section of the gene, which does not produce a gene product but likely influences chromatin—the complex of DNA and proteins that make up chromosomes—spatial structure and causes differences in gene expression.

They relied on brain tissue samples from dogs provided by the ELTE University’s Canine Brain and Tissue Bank in Budapest.

"Brainstem samples were collected from pet dogs euthanized for medical reasons and donated for research. We included only dogs without major nervous system illnesses," explains Dr. Eniko Kubinyi, head of the Department of Ethology at ELTE, who established the bank with geneticist Dr. Sára Sándor and veterinarian Dr. Kálmán Czeibert andmaintains it with grants from the Hungarian Academy of Sciences. "The examined gene regulates the expression of other genes, so its expression is expected throughout the brain."

The study found that the ancient and modern variants of GTF2I affect the chromatin loop shape differently.

"Novel regulatory DNA segments caused by retrotransposon insertions are generally eliminated from the genome. Interestingly, within an intron of the GTF2I gene, the ancient wolf genome largely co-opts the inserted segment, while the modern dog genome rejects it. The presence or absence of this retrotransposon is associated with altered 3D chromatin structure at GTF2I, with possible downstream impacts on pathways regulating the extra-cellular matrix and GTF2I splicing. This is similar to the humans’ case, where many WB patients have cranio-facial abnormalities explained by extra-cellular matrix anomalies and altered GTF2I function. Essentially, we report putative molecular convergence between hyper-social behaviour in dogs and human Williams-Beuren syndrome," emphasizes Dr. Dhriti Tandon, the first author of the study.

When certain species preserve the same mutation while others do not—as seen in the difference between wolves and dogs—the regulatory effect is likely evolutionarily significant. In the absence of retrotransposons, a DNA loop present in wolves does not form in dogs, which may explain some of the differences in neurocognitive profiles and hence social behaviors between the two species.

The researchers hope that their results will highlight that not only the genomic base sequence, but also its 3D structure, influences behaviour.

Original Article: Dhriti Tandon, D., Kubinyi, E., Sándor, S., Faughnan, H., Miklósi, Á., vonHoldt, B.M. (2024) Canine Hyper-Sociability Polymorphism associated with Altered Three-Dimensional Chromatin State. BMC Genomics, 25:767. https://bmcgenomics.biomedcentral.com/articles/10.1186/s12864-024-10614-6

Funding: The study was partly supported by the Hungarian Academy of Sciences via a grant to the MTA-ELTE ‘Lendület/Momentum’ Companion Animal Research Group (grant no. PH1404/21) and the National Brain Programme 3.0 (NAP2022-I-3/2022), and the Animal Behavior Society: Student Research Grant.

Journal

BMC Genomics

DOI

10.1186/s12864-024-10614-6

Article Title

Canine hyper-sociability structural variants associated with altered three-dimensional chromatin state

Work-related stress may increase the risk of an irregular heart rhythm

Job strain and effort-reward imbalance at work were associated with a greater chance of developing an abnormal heart rhythm condition, finds new study in the Journal of the American Heart Association

American Heart Association

Research Highlights:

Adults in white-collar jobs in Canada with high job strain and for whom significant efforts are met with low rewards (such as low salary or recognition) may face a 97% increased risk for developing the irregular heart rhythm condition known as atrial fibrillation, or AFib or AF, compared to workers not exposed to these work stressors.
Separately, high job strain alone was associated with an 83% higher risk of developing AFib, and effort-reward imbalance alone was associated with a 44% greater risk.
Recognizing and addressing these stressors at work may be an effective strategy to prevent atrial fibrillation in adults, researchers said.

DALLAS, Aug. 14, 2024 — Work-related stress caused by job strain and an imbalance between efforts applied vs. rewards received may increase the risk of developing atrial fibrillation, according to new research published today in the Journal of the American Heart Association, an open access, peer-reviewed journal of the American Heart Association.

Also known as AFib or AF, atrial fibrillation is the most common form of arrhythmia – an abnormal heart rhythm. It can lead to stroke, heart failure or other cardiovascular complications. More than 12 million people are projected to have AFib in the United States by 2030, according to the American Heart Association’s 2024 heart disease and stroke statistics.

Previous research linked high job strain and effort-reward imbalance at work with an increased risk of coronary heart disease. This research is the first to examine the adverse effect of both psychosocial stressors at work on atrial fibrillation, said the study’s senior author Xavier Trudel, Ph.D., an occupational and cardiovascular epidemiologist and associate professor at Laval University in Quebec City, Quebec, Canada.

“Our study suggests that work-related stressors may be relevant factors to include in preventive strategies,” Trudel said. “Recognizing and addressing psychosocial stressors at work are required to foster healthy work environments that benefit both individuals and the organizations where they work.”

Trudel and team studied the impact of job strain, which refers to a work environment in which employees face high job demands, such as a heavy workload and tight deadlines, and low control over their work with little say in decision-making and how they execute their tasks.

Another factor assessed in the study was the effort-reward imbalance. This occurs when employees invest significant effort into their work but perceive the rewards they get in return — such as salary, recognition or job security — as insufficient or unequal to their performance.

Researchers examined medical database records for nearly 6,000 adults in white-collar jobs in Canada, with 18 years of follow-up data. The analysis found that:

employees who said they experienced high job strain had an 83% higher risk of developing AFib compared to workers unaffected by the stressors;
those who perceived an effort-reward imbalance had a 44% greater risk, compared to workers who did not report this imbalance; and
combined perceptions of high job strain and effort-reward imbalance were associated with a 97% increased risk of AFib.

“The effectiveness of workplace interventions to reduce psychosocial stressors that may also reduce the risk of AFib should be investigated in future research efforts,” Trudel said. “Our research team previously conducted an organizational intervention designed to reduce psychosocial stressors at work, which was shown to effectively reduce blood pressure levels. Examples of organizational changes implemented during the intervention included slowing down the implementation of a large project to prevent increased workload; implementing flexible work hours; and holding meetings between managers and employees to discuss day-to-day challenges.”

Limitations of the study include that participants were all white-collar workers encompassing managers, professional and office workers in Canada which means results may not apply to other types of workers or to workers in other countries.

Study details, background or design:

Researchers collected data through the PROspective Quebec (PROQ) Study on Work and Health, which started in the Quebec region in 1991-1993 and recruited white-collar workers from 19 public and semi-public organizations.
A total of 5,926 workers (49% men, 51% women) were included in this analysis. Their average age was 45 at the beginning of the study (1999-2001) and 65 at the end of the follow-up (Dec. 2018). Most study participants were white adults.
Work stress was assessed from self-reported questionnaires.
The analysis identified 186 AFib cases, and among that group, 19% of the people with AFib reported high job strain; 25% said they perceived effort-reward imbalance; and 10% reported experiencing both stressors simultaneously.
More than one-third of participants had been diagnosed with coronary heart disease or heart failure before their AFib incidence.
The study measured the work-related stressors through self-reported questionnaires specifically on job strain and effort-reward imbalance, controlling for a broad list of socioeconomic characteristics (sex and education), health risks (diabetes status and high blood pressure) and lifestyle factors (smoking and alcohol).

Co-authors, disclosures and funding sources are listed in the manuscript.

Studies published in the American Heart Association’s scientific journals are peer-reviewed. The statements and conclusions in each manuscript are solely those of the study authors and do not necessarily reflect the Association’s policy or position. The Association makes no representation or guarantee as to their accuracy or reliability. The Association receives funding primarily from individuals; foundations and corporations (including pharmaceutical, device manufacturers and other companies) also make donations and fund specific Association programs and events. The Association has strict policies to prevent these relationships from influencing the science content. Revenues from pharmaceutical and biotech companies, device manufacturers and health insurance providers and the Association’s overall financial information are available here.

Additional Resources:

Multimedia is available on the right column of release link http://newsroom.heart.org/news/work-related-stress-may-increase-the-risk-of-an-irregular-heart-rhythm?preview=fda43df8a3977e18e323b52c3e660d44
After Aug. 14, view the manuscript online.
AHA news release: Job strain combined with high efforts and low reward doubled men’s heart disease risk (Sept. 2023)
AHA news release: Work-related stress linked to increased risk for peripheral artery disease (April 2020)
AHA health information: Stress and Heart Health
AHA initiative: Well-being Works Better™
Follow AHA/ASA news on X @HeartNews
Follow news from the Journal of the American Heart Association @JAHA_AHA

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About the American Heart Association

The American Heart Association is a relentless force for a world of longer, healthier lives. We are dedicated to ensuring equitable health in all communities. Through collaboration with numerous organizations, and powered by millions of volunteers, we fund innovative research, advocate for the public’s health and share lifesaving resources. The Dallas-based organization has been a leading source of health information for a century. During 2024 - our Centennial year - we celebrate our rich 100-year history and accomplishments. As we forge ahead into our second century of bold discovery and impact, our vision is to advance health and hope for everyone, everywhere. Connect with us on heart.org, Facebook, X or by calling 1-800-AHA-USA1.

Journal

Journal of the American Heart Association

Article Publication Date

14-Aug-2024

A method that paves the way for improved fuel cell vehicles

Chalmers University of Technology

image:
Researchers at Chalmers University of Technology, Sweden, have developed an innovative method to study and understand how fuel cells degrade over time, using advanced electron microscopes . This is an illustration of a catalyst layer sample on a transmission electron microscope grid, placed between an electrode and a gas diffusion layer.
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Credit: Chalmers University of Technology | Linnéa Strandberg and Victor Shokhen

More efficient and longer-lasting fuel cells are essential for fuel cell-powered heavy-duty hydrogen vehicles to be an alternative to combustion fuelled counterparts. Researchers at Chalmers University of Technology, Sweden, have developed an innovative method to study and understand how parts of fuel cells degrade over time. This is an important step towards the improved performance of fuel cells and them becoming commercially successful.

Hydrogen is a fuel alternative that is becoming increasingly interesting for heavy-duty vehicles. Hydrogen-powered vehicles only emit water vapour as exhaust, and if the hydrogen is produced using renewable energy, it is completely free of carbon dioxide emissions. Unlike battery-powered electric vehicles, hydrogen-powered vehicles do not need to burden the electricity grid, as hydrogen can be produced and stored when electricity is cheap. For some hydrogen-powered vehicles the propulsion comes from a so-called fuel cell. However, hydrogen-fuel-cell-powered vehicles are limited by a relatively short lifespan, because fuel cell components, such as electrodes and membranes, degrade over time. It is this problem that the recent study addresses.

Researchers at Chalmers University of Technology have developed a new method for studying what affects the ageing of fuel cells by tracking a specific particle in the fuel cell during use. The team of researchers have studied an entire fuel cell by taking it apart at regular intervals. Using advanced electron microscopes, they have then been able to follow how the cathode electrode degrades in specific areas during the cycles of use. Previous studies have been done on so-called half-cells, which are similar (but not the same as) half of a fuel-cell and are carried out under conditions that differ significantly from the real fuel cell.

Better understanding with new experimental method

"It has previously been assumed that the performance would be affected by the fuel cell being disassembled and studied in the way we have done, but it turned out that this assumption is not correct, which is surprising," says research leader Björn Wickman, Associate Professor at the Department of Physics at Chalmers.

The researchers at Chalmers have been able to explore how the material in the fuel cell degrades at both the nano and micro level, and pinpoint exactly when and where the degradation occurs. This provides valuable information for the development of new and improved fuel cells with a longer lifespan.

"From previously only looking at how the fuel cell has aged after use, we have now been able to look into the middle stage," says doctoral student Linnéa Strandberg at Chalmers. “Being able to follow a single, chosen particle within a specific area, provided a much better understanding of the degradation processes. Greater knowledge of these is an important step on the way to designing new materials for fuel cells or to adjust the control of the fuel cell.”

New method paves way for longer lasting fuel cells

The U.S. Department of Energy (DOE) has pointed out that improved lifetime of fuel cells is one of the most important goals to reach before fuel cell-powered hydrogen vehicles can become commercially successful. According to the industry, a truck needs to be able to withstand 20,000 – 30,000 hours of driving over its lifetime, which a fuel cell-powered hydrogen truck cannot achieve today.

"We have now laid a foundation on which to build for the development of better fuel cells. Now we know more about the processes that take place in the fuel cell and at what point over the lifetime of the fuel cell they occur. In the future, the method will be used to develop and study new materials that can give the fuel cell a longer lifespan," says Björn Wickman.

Facts: How a fuel cell works

The core of a fuel cell consists of three active layers, two electrodes – anode and cathode respectively – with an ion-conducting membrane in the middle. Each individual cell provides a voltage of about 1 volt. The electrodes contain catalyst material, and hydrogen and oxygen are added to them. The resulting electrochemical process generates clean water and electricity that can be used to power a vehicle.

More about the research:

The research group at Chalmers that has developed the method consists of doctoral student Linnéa Strandberg and Associate Professor Björn Wickman, both at the Department of Physics, Victor Shokhen, former postdoc at the Department of Physics, and Magnus Skoglundh, professor at the Department of Chemistry and Chemical Engineering.

The research has been presented in three different scientific articles:

Carbon Support Corrosion in PEMFCs Followed by Identical Location Electron Microscopy, ACS Catalysis, 16 May 2024.
Fuel cell electrode degradation followed by identical location transmission electron microscopy (Journal of Material Chemistry A, 4 September 2023)
Impact of Accelerated Stress Tests on the Cathodic Catalytic Layer in a Proton Exchange Membrane (PEM) Fuel Cell Studied by Identical Location Scanning Electron Microscopy (ACS Applied Energy Materials, 18 August 2022)

This project was financially supported by the Swedish Foundation for Strategic Research and the Swedish Research Council and performed within the Competence Centre for Catalysis, which is hosted by Chalmers University of Technology and financially supported by the Swedish Energy Agency and the member companies Johnson Matthey, Perstorp, Powercell, Preem, Scania CV, Umicore and Volvo Group.

Scanning electron microscopy and transmission electron microscopy were performed at Chalmers Materials Analysis Laboratory (CMAL).

Using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), the researchers have been able to show how the electrode degrades during use, when performing a standardised stress test. It is clear how cracks grow in the electrode film in the upper two rows. In the lower row, carbon substrates and platinum particles are visible. During use, the carbon decreases in volume and changes shape, while the platinum particles grow. The graphs on the right show how the data correlates with the electrochemical performance.

After the scanning electron microscopy, the cell housing is assembled with the sample inside for further stress tests.