How do horticultural crops defend themselves against fungal pathogens?

NANJING AGRICULTURAL UNIVERSITY THE ACADEMY OF SCIENCE

image: Physical barriers and phytochemicals involved in resistance of horticultural crops to fungal pathogens

Recently, scientists from the Chinese Academy of Sciences summarized recent research progress on defense responses of horticultural crops to fungal pathogens and novel strategies to regulate the induction of plant resistance, as well as problems, challenges, and future research directions.

Phytochemicals with antimicrobial effects are important components of defense systems in plants. Among such phytochemicals, phytoalexins are induced by external factors, whereas phytoanticipins occur naturally or increase after induction. Antimicrobial phytochemicals are classified according to their chemical structures and are primarily phenolics, flavonoids, coumarins, lignins, terpenoids, alkaloids, glucosinolates, and stilbenes. Phenolics and flavonoids are secondary metabolites that constitute one of the most common and extensive groups of phytochemicals. These compounds inhibit pathogens by inducing membrane lipid peroxidation, which disrupts fungal cell membrane permeability and mitochondrial function. Similarly, terpenoids inhibit fungal growth and also induce disease resistance. The other phytochemicals also exhibit strong and stable broad-spectrum antifungal activity, suggesting that they could be developed as alternatives to chemical fungicides.

When fungal pathogens penetrate physical barriers by modifying or degrading host cell walls, pattern recognition receptors (PRRs) may recognize conserved damage-associated molecular patterns (DAMPs) from plants or pathogen-associated molecular patterns (PAMPs) from pathogens and activate pattern-triggered immunity (PTI). Fungal pathogens can secrete effectors or virulence factors, which may be recognized by nucleotide-binding and leucine-rich repeat (NB-LRR or NLR) proteins and other plant resistance (R) proteins. Such recognition may result in further effector-triggered immunity (ETI), which is postulated to be an accelerated and amplified PTI response. A varied number of NB-LRR genes exhibit special evolutionary patterns among plant species. To date, only a few NB-LRR genes have been confirmed to function in response to fungal pathogens. Further in-depth exploration of potential NB-LRRs and their mechanisms of action may substantially enrich our arsenal to counterstrike against fungal pathogens.

To prevent further fungal pathogen invasion, plants have developed a series of responses that include the hypersensitive response (HR), cell wall modification, stomatal closure, callose deposition, phytoalexin production, and toxin degradation. After local defense responses are induced, systemic signaling may activate resistance in other adjacent tissues. Both PTI and ETI can trigger the production and long-distance transport of signaling molecules to induce systemic acquired resistance (SAR) and herbivore-induced resistance (HIR). SAR is mediated primarily by salicylic acid (SA) signaling and to a lesser extent by N-hydroxypipecolic acid (NHP). In contrast to SAR, HIR is modulated by jasmonic acid (JA) and ethylene (ET). Crosstalk among SA, JA, and ET, both synergistic and antagonistic, is common and crucial for defense responses against fungal pathogens.

The overuse of traditional fungicides and antimicrobial agents has increased pathogen resistance to these compounds and also threatens food safety and the environment. Therefore, new strategies must be developed for efficient disease control to meet requirements for the sustainable development of the agricultural industry. The latest studies indicate that the induction of intrinsic resistance in horticultural crops via regulatory elements is both feasible and efficient. The discovery of cross-kingdom RNA trafficking has provided new prospects for crop protection. The necrotrophic fungus B. cinerea can produce small RNAs (sRNAs) that function as effectors to suppress host immunity. In turn, host plants introduce sRNAs into B. cinerea via extracellular vesicles that suppress the expression of genes associated with pathogenicity. Overexpression or knockdown of transferred host sRNAs can either promote or reduce host resistance. Environmental double-stranded RNA (dsRNA) can be taken up by many eukaryotic microbes with varying efficiency, and topical application of dsRNA with high RNA uptake efficiency can markedly inhibit plant disease symptoms.

Translational control of mRNA through the editing of regulatory elements may be another efficient way to induce resistance in horticultural crops. Upstream open reading frames (uORFs) have widespread regulatory roles in modulating mRNA translation in eukaryotes. Moreover, transgene-free lines of plants with improved traits are readily obtained with CRISPR/Cas9, which has broad implications for crop improvement. Because uORFs are found extensively in eukaryotic mRNAs, these regulatory elements could be manipulated to enhance broad-spectrum resistance with minimal adverse effects on normal growth, substantially promoting the genetic improvement of horticultural crops.

“Because of the importance of fungal disease in pre- and postharvest loss of horticultural crops, we focused on plant-pathogen interactions and control technology. Moreover, development and application of omics technologies have provided large data sets at multiple levels, which have further broadened insights into the defense responses against fungal pathogens,” Prof. Tian said. The review paper also examined the limitations of previous studies and proposed future research directions for genetic improvement of resistance in horticultural crops.

 

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Reference

Authors

Xiaodi Xu1,2,†, Yong Chen1,†, Boqiang Li1, Zhanquan Zhang1, Guozheng Qin1, Tong Chen1,* and Shiping Tian1,2,*

Affiliations

1 Key Laboratory of Plant Resources, Institute of Botany, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing 100093, China

2 College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China

About Prof. Shiping Tian 

Prof. Shiping Tian received her bachelor's degree from Sichuan Agricultural University in 1982. In 1995, she received her doctoral degree in plant pathology from the University of Bologna in Italy. She returned to China in 1997. Now she is a researcher at the Institute of Botany, Chinese Academy of Sciences. In 2002, she won the National Science Fund for Distinguished Young Scholars. To date, she has published more than 140 SCI papers.

Particles from everyday wall paints can harm living organisms – novel membrane shows high filtering effects

Analyzing two typical dispersion paints, researchers from the University of Bayreuth have discovered a large number of solid particles in them which are only a few micro- or nanometers in size. These particles can harm living organisms

Peer-Reviewed Publication

UNIVERSITÄT BAYREUTH

Dispersion paints are mostly used in households for painting walls and ceilings. An interdisciplinary research team from the University of Bayreuth has now analysed the chemical composition of two typical dispersion paints and discovered a large number of solid particles in them which are only a few micro- or nanometers in size. Studies on biological test systems showed that these particles can harm living organisms. Using a novel membrane developed at the University of Bayreuth, these particles can be filtered out of water before they enter the environment.

Ingredients of dispersion paints

The Bayreuth study on the ingredients of dispersion paints and their possible effects on living organisms has been published in the journal Ecotoxicology and Environmental Safety. It is based on close interdisciplinary networking in Collaborative Research Center 1357 "Microplastics" at the University of Bayreuth. The scientists selected two commercially available dispersion paints that are frequently used in households. These differ primarily in their dripping properties, because they were developed for wall painting on the one hand and ceiling painting on the other. The two paints have a solids content of 49 and 21 percent by weight, respectively, while the organic content is 57 and seven percent by weight. Characteristic solid components in the micro- or nanometer range are particles of silicon dioxide, titanium dioxide and calcium carbonate, as well as particles of various kinds of plastic, especially polyacrylate.

"Many of these tiny particles enter the environment, for example, through abrasion of the paint layers or weathering. Our study now shows that when brushes, rollers, scrapers and buckets used in painting walls and ceilings are cleaned by washing out paint residues, the particles from the dispersion paints can end up in wastewater and thus also in the environment. The impact on the environment needs to be thoroughly investigated, which is all the more urgent given the worldwide spread of dispersion paints and their diverse material compositions. That is why we have not limited ourselves to the chemical analysis of paint components, but have also investigated their effects on living organisms and cells," says Prof. Dr. Andreas Greiner, deputy spokesman of the Collaborative Research Center "Microplastics".

Effects on living organisms

For their inquiries, the Bayreuth scientists selected two test systems which have been well established in research: water fleas of the species Daphnia magna and a line of mouse cells. The water fleas were tested according to OECD guidelines for the testing of chemicals. In this test, the mobility of the organisms is considered. It was found that the mobility of the water fleas was significantly reduced when the water contained a high proportion of dissolved and undissolved inorganic nanoplastic and microplastic particles. In mouse cells, a decrease in cell activity was observed, which was generally caused by particles in the nanometer range. Metabolism in the mouse cells was significantly disrupted by nanoparticles of titanium dioxide and plastics in particular.

"Our research shows that the ingredients of dispersion paints can cause reactions of varying degrees in organisms and cells. Therefore, the possibility that the ingredients could be harmful to the environment cannot be ruled out. Further research in this area is urgently needed, especially since we still know far too little about whether interactions between nanoparticles made of plastic and inorganic nanoparticles can trigger additional damage," explains Prof. Dr. Christian Laforsch, spokesman for the Collaborative Research Center "Microplastics". "It is likewise still a largely unresolved question how the ingredients of dispersion paints interact with other substances in different environmental compartments – for example, in the air, in the soil or in rivers. However, it is already clear that dispersion paints should not be carelessly disposed of in the environment," says Prof. Dr. Ruth Freitag, who is Chair of Process Biotechnology at the University of Bayreuth.

A novel membrane with high filtering effects

Parallel to the studies of dispersion paints and their possible effects, researchers under the direction of Prof. Dr. Andreas Greiner have focussed on a further project: They have developed a new process to remove potentially harmful particles from dispersion wall paints from wastewater by filtration. This involves the use of a membrane made of functionalized fibers produced by the electrospinning process. The membrane retains micro- and nanometer-sized particles in different ways. On the one hand, the pores of the membrane are so fine that microparticles are not allowed to pass through. On the other hand, interactions between the membrane fibers and nanoparticles cause them to stick to the membrane surface even though they would fit into the pores. In both cases, the filtering effect is not associated with rapid and large-scale clogging of the pores. Therefore, water, for example, can easily pass through the membrane and run off.

In the journal Macromolecular Materials and Engineering, the Bayreuth scientists describe the successful application of the membrane. They also tested the two dispersion paints that had proved potentially harmful to living organisms in the study. As it turned out, the membrane is able to retain typical colour components – in particular nanoparticles of titanium dioxide and polyacrylate, and microparticles of calcium carbonate. "In everyday life, all these colour components are discharged together into the wastewater. Here they mix and in some cases even change their structures and properties due to their interactions. Therefore, we specifically tested the filtration performance of our electrospun membrane on such mixtures. The high filtering effects we have achieved show that this process has great potential when it comes to purifying water from particles in the micro and nanometer range, such as those contained in commonly used paints around the world," says Greiner.

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JOURNAL

Ecotoxicology and Environmental Safety

DOI

10.1016/j.ecoenv.2022.113877 

METHOD OF RESEARCH

News article

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Disentangling biological effects of primary nanoplastics from dispersion paints’ additional compounds

POSTMODERN ALCHEMY

How a Japanese herbal medicine protects the gut against inflammatory bowel disease

Peer-Reviewed Publication

RIKEN

 

IMAGE: THE CONDITION OF MICE WITH COLITIS IMPROVED AFTER TREATMENT WITH DAIKENCHUTO, A MEDICINE MADE FROM GINGER, GINSENG, AND JAPANESE PEPPER. ANALYSIS SHOWED THAT THIS WAS BECAUSE IT PREVENTS THE LOSS OF KEY BACTERIA IN THE GUT AND FACILITATES THE ACTIVITY OF INNATE IMMUNE CELLS IN THE GUT CALLED ILC3S. view more 

CREDIT: RIKEN

Zhengzheng Shi and colleagues at the RIKEN Center for Integrative Medical Sciences (IMS) in Japan report the effects of a common herbal remedy on colitis, one of two conditions that comprise inflammatory bowel disease (IBD). Published in Frontiers in Immunology, the study shows that DKT—an herbal medicine containing ginger, pepper, ginseng, and maltose—reduced the severity of colitis in lab mice by preventing the loss of important gut bacteria and by increasing levels of immune cells in the colon that fight inflammation.

Colitis is a chronic inflammation of the colon, characterized by an imbalance in gut bacteria and an abnormal immune response. Prevalence has doubled over the last 20 years, and it’s currently a global health concern, particularly in Europe and North America. Although treatments are numerous, they are only partially effective. This has led some researchers to take a closer look at traditional herbal medicines that originated in China, and are now commonly used in Japan and other Asian countries.

Daikenchuto (DKT) is a formula containing specific amounts of ginger, pepper, ginseng, and maltose, and is one of 148 herbal medicines called Kampo, which have been developed in Japan and are often prescribed by doctors to treat a variety of illnesses. Previous research has hinted that DKT might be useful for treating colitis, but evidence, particularly at the molecular level, has been lacking. Thus, Shi and the team of researchers at RIKEN IMS led by Naoko Satoh-Takayama conducted a detailed examination of its effects on a mouse model of colitis.

Colitis was induced in mice using dextran sodium sulfate, which is toxic to the cells that line the colon. When these mice were given DKT, their body weights remained normal, and they had lower clinical scores for colitis. Additional analysis revealed much less damage to the cells lining the colon. Having thus shown that DKT does indeed help protect against colitis, the researchers proceeded to analyze the gut microbiome of the mice and expression levels of anti-inflammatory immune cells.

Gut microbiomes contain numerous bacteria and fungi that aid in digestion and help the immune system. Colitis is associated with an imbalance in these gut microbiota, and analysis showed that a family of lactic acid bacteria were depleted in the colitic mice of this study. Also depleted was one of their metabolites, a short-chain fatty acid called propionate. Treating the model mice with DKT restored much of these missing bacteria—particularly those from the genus Lactobacillus—and levels of propionate were normal.

Colitis is also associated with an abnormal immune response that causes the characteristic intestinal inflammation. When the team looked at innate intestinal immune cells, they found that levels of a type called ILC3 were lower in the untreated colitic mice than in the DKT-treated colonic mice, and that mice engineered to lack ILC3 suffered more and could not benefit from DKT treatment. This means that ILC3s are critical for protecting against colitis and that DKT works by interacting with them. Lastly, qPCR analysis indicated that these important immune cells had receptors for propionate, called GPR43, on their surface.

“Daikenchuto is commonly prescribed to prevent and treat gastrointestinal diseases, as well as for reducing intestinal obstruction after colorectal cancer surgery,” says Satoh-Takayama. “Here we have shown that it can also alleviate intestinal diseases like colitis by rebalancing Lactobacillus levels in the gut microbiome. This likely helps reduce inflammatory immune responses by promoting the activity of type 3 innate lymphoid cells.”

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JOURNAL

Frontiers in Immunology

DOI

10.3389/fimmu.2022.903459 

New principles for biological fieldwork will build equity for researchers and local communities

Peer-Reviewed Publication

UNIVERSITY OF KANSAS

 

IMAGE: FIELDWORK IN REMOTE FORESTED SITES IN THE PHILIPPINES USUALLY INVOLVES BACK-COUNTRY CAMPING CONDITIONS, LATE NIGHTS CATCHING ANIMALS AND LONG DAYS WORKING — IN DIVERSE GROUPS OF COLLABORATING FACULTY, STUDENTS AND REPRESENTATIVES OF INDIGENOUS PEOPLES’ GROUPS — TO CAPTURE DATA AND PROPERLY PRESERVE SPECIMENS. HERE RAFE BROWN, FACULTY MEMBERS AND STUDENTS FROM ATENEO DE NAGA UNIVERSITY DISCUSS TECHNIQUES FOR RECORDING DATA FROM SPECIMENS BOUND FOR KU. view more 

CREDIT: MICHAEL CUESTA

LAWRENCE — For hundreds of years, teams of biologists have carried out fieldwork around the globe, often trekking to remote places to collect specimens and data about our natural world. Today, such work can demand collaboration between large international teams of biologists, extensive permitting with authorities, interaction with local communities and research plans often led by one or two senior investigators.

Too often, these factors can result in power imbalances between researchers and local communities where fieldwork takes place. Moreover, inequities based on race, gender, sexual orientation and seniority can develop within the teams of researchers themselves.

Now, a new paper appearing in the Proceedings of the National Academy of Sciences lays out a set of principles for biological fieldwork designed to lessen inequities between researchers and local populations, as well as internally among research teams themselves. Many “best practices” in the paper are adapted from procedures for permitting and licensing developed over years at the University of Kansas Biodiversity Institute and Natural History Museum.

“When I was invited by colleagues at Berkeley to be part of this conversation, I was really happy to contribute,” said co-author Rafe Brown, curator-in-charge of the Herpetology Division at KU’s Biodiversity Institute. “After more than 30 years of working in the Philippines, I had lots of experience in managing groups of people working together in the field. I'd seen a lot of things work out well, and a lot of things work out so-so, where we needed some improvement in the way we interact, as groups of people, working often in remote and stressful field conditions. I’ve seen some real trainwrecks of group psychology during fieldwork — and things that just struck me as potentially dangerous. I never had any real disasters myself, but I saw some risky and even scary behavior, and heard a lot of stories over the years, in my early career, and in grad school.”

KU’s Biodiversity Institute is seen as a leader in collaborating with local authorities and populations to make sure biological fieldwork is ethical, legal and safe — in part because of its extensive checklists and procedures for permitting and licensing. Supplemental documents to the PNAS paper — a Field Safety Plan Template and a Scientific Permit Checklist – are adapted in part from KU’s procedures.

“I’d like to see these shared widely and adopted by institutions around the world as a foundation for fieldwork planning,” said Lori Schlenker, assistant director of collections and facilities at the Biodiversity Institute. “We’re committed to participating in safe and legal fieldwork and training the next generation of students to be able to lead their own programs and mentor their own students in these practices when they graduate from KU. We’ve been building on our experiences — good and bad — and have developed procedures so that prior to departure, permits are in place and researchers have considered how they will collect, export and import research specimens safely, legally and ethically. This ensures that resources are not expended on specimens that we cannot legally accession into our collections. Most importantly, the safety of all field team members is critical. Applying the experience of our BI researchers, and with guidance from KU, emphasis is placed on communication and transparency as part of the fieldwork planning process.”

Much of this to hone the way KU biologists tackle permitting and interacting with local authorities and communities has taken place in the Philippines, where Biodiversity Institute personnel strive for locally inclusive fieldwork.

"Our 15-year, multi-institutional collaboration with KU has resulted the traditional products and outputs — like students trained, papers published, grants obtained — but it has also profited from many deep discussions and steps taken, to correct the past landscape of exclusively foreigner-led, expeditionary fieldwork,” said co-author Tess Sanguila of Father Saturnino Urios University in the Philippines. “Additionally, here within the country, our own scientific community often only considers and prioritizes the contributions and inputs from the so-called experts in the capital city over those of the researchers from the provinces in the southern Philippines, who are stereotyped as being of inferior expertise. This paper provides a simplified and practical starting point, from which we hope to establish a solution to this whole imbalanced culture, and from which we fundamentally advocate to ‘support local’ for more inclusive and invigorated long-term collaborations of the future." 

The PNAS paper advocates four main principles for fieldwork to promote “equity, reciprocity, access, benefit-sharing and safety”:

• Be collaborative: We embrace collaborative science and fieldwork practices with our partners, field teams and the communities with whom we work.
• Be respectful: We prioritize local sovereignty and long-term benefits for the community, and we invest time and effort in learning about and respecting local history and cultures.
• Be legal: We commit to obtaining all necessary permits, authorizations, and land permissions, and to following all legal guidelines and requirements.
• Be safe: We work proactively to promote a safe physical and emotional environment for all members of research teams and local communities with clear guidance and communications.

Lead author Valeria Ramírez Castañeda, doctoral student in integrative biology at the University of California, Berkeley, said her own time conducting biological fieldwork in the Amazon inspired her work on the paper.

“My own personal experience comes from the Global South,” Castañeda said. “I’m Colombian, and my focus was in particular on how we interact with local communities when conducting fieldwork. My research in biology takes place in the Colombian Amazon, where I work with predator-prey interactions between snakes and frogs. The local community — biologists, drivers, field assistants, among others — sustain and inform my work there. However, are we scientists reciprocal when it comes to thinking about benefits and acknowledgments for the community? I’ve been trying to change or at least acknowledge practices that exclude the local communities from research. I was born in the biggest city in Colombia — Bogotá — so I was an uninvited guest in the Amazon territory. I’ve been trying to get to know the community where I work, ask for consent for every procedure, explain my research, collaborate with biologists and field assistants from indigenous and local communities, and participate in community-science projects.”

In addition to working with local populations and authorities, the new paper offers recommendations to alleviate power asymmetries that can plague fieldwork teams internally.

“With all the recent civil unrest in the U.S. and the existing inequities that have been exacerbated by the pandemic, it’s a good time to reevaluate how we do things in our profession because people are listening and reflecting,” said Rebecca Tarvin, assistant professor of integrative biology at the University of California, Berkeley. “Personally, I’ve wanted to think more deeply about field biology for some time. I didn’t receive any formal training on how to do collaborative science involving fieldwork and I think this is largely true for others in field biology. The way people conduct fieldwork thus often depends on the norms and culture of their lab and on the default approaches to doing science. However, doing equitable science takes intentional planning, and many default approaches are not equitable. That’s why we wanted to provide some general guidelines that can help anyone proactively plan more equitable research programs.”

Tarvin added that data show diverse teams can produce more innovative and robust research.

“Having diverse groups doing fieldwork in a way that is fair, open and collaborative with the people living where we work has the further benefit of including everyone in conducting, communicating and benefiting from science,” she said.

CAPTION

The authors advocate four main principles for fieldwork to promote “equity, reciprocity, access, benefit-sharing and safety."

CREDIT

Ramírez-Castañeda, et al.

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JOURNAL

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.2122667119 

Assessing the effect of hydraulic fracturing on microearthquakes

New research examines mining sites with hydraulic fracturing comparing it to those without to determine the practice’s effect on seismic hazards

Peer-Reviewed Publication

SPRINGER

The analysis of low-intensity human-caused microearthquakes, including their magnitude and frequency, has become an important factor in mining. This is a consideration not only for the safety of mining staff, but also for extraction rates and mine stability that can have major impacts on business performance.

Increasingly, the practice of hydraulic fracturing is used to precondition mines and diminish the magnitude of induced tremors as well as reduce the number of rock fragments extracted.

A new paper published in EPJ B assesses the impact of hydraulic fracturing on seismic hazards like microearthquakes, an important issue for the safety of workers and the continuation of mining operations. The paper is authored by Erick de la Barra, Pedro Vega-Jorquera and Héctor Torres from the University of La Serena, Chile, alongside Sérgio Luiz E. F. da Silva from Politecnico di Torino, Department of Applied Science and Technology, Turin, Italy.

Hydraulic fracturing involves pumping large quantities of fluids into a wellbore at high pressures. This has the effect of enlarging fractures in the target rock formation. This results in an increase in the yield of oil or gas from rocks — especially from low-permeability rocks like tight sandstone, shale and occasionally coal beds.

The authors attempt to quantify the benefits of preconditioning with hydraulic fracturing by integrating previous investigative models to create a more realistic approximation of the seismic ruptures.

This model was applied to a mine in the O’Higgins Region of Chile to assess induced seismic activity due to the effect of hydraulic fracturing. The team also considered both the magnitude of microearthquakes and the intervening time between events.

This was done by considering 15,436 microearthquakes recorded between 2003 and 2008 in three sections of the mine. These were then compared on the basis of whether the section had been preconditioned with hydraulic fracturing or not.

The results seemed to imply that hydraulic fracturing decreases the magnitude and the microearthquakes.

The model worked on by the team could also be utilised to predict seismic activity, and to understand so-called marsquakes occurring on the Red Planet. 

“In reference to the next step in this investigation, our interest is to work with the problem when self-similarity is broken,” Vega-Jorquera says. “Thus, considering the problem of multisources and relating them to multimodal distributions, this would imply evaluating possible modifications of the seismic hazard via hydraulic fracturing.”

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References

de la Barra, E., Vega-Jorquera, P., da Silva, S.L.E.F. et al. Hydraulic fracturing assessment on seismic hazard by Tsallis statistics. Eur. Phys. J. B 95:92 (2022). https://doi.org/10.1140/epjb/s10051-022-00361-6

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JOURNAL

The European Physical Journal B

DOI

10.1140/epjb/s10051-022-00361-6 

ARTICLE TITLE

Hydraulic fracturing assessment on seismic hazard by Tsallis statistics

Geological carbon sequestration in mantle rocks prevents large earthquakes in parts of the San Andreas Fault

Smaller, more frequent quakes help to reduce tectonic

strain

Peer-Reviewed Publication

WOODS HOLE OCEANOGRAPHIC INSTITUTION

 

IMAGE: OUTCROP OF CARBONATE-ALTERED MANTLE ROCK IN THE SAN ANDREAS FAULT AREA. A RECENT STUDY SHOWS THAT CARBON SEQUESTRATION IN MANTLE ROCKS MAY PREVENT LARGE EARTHQUAKES IN PARTS OF THE SAN ANDREAS FAULT. view more 

CREDIT: IMAGE CREDIT: FRIEDER KLEIN/©WOODS HOLE OCEANOGRAPHIC INSTITUTION

Woods Hole, MA - The San Andreas Fault in California is renowned for its large and infrequent earthquakes. However, some segments of the San Andreas Fault (SAF) instead are characterized by frequent quakes of small to moderate magnitude and high rates of continuous or episodic aseismic creep. With tectonic strain released in a quasi-steady motion, that reduces the potential for large earthquakes along those segments.

Now, researchers say ubiquitous evidence for ongoing geological carbon sequestration in mantle rocks in the creeping sections of the SAF is one underlying cause of aseismic creep along a roughly 150 kilometer-long SAF segment between San Juan Bautista and Parkfield, California, and along several other fault segments.

“Although there is no consensus regarding the underlying cause of aseismic creep, aqueous fluids and mechanically weak minerals appear to play a central role,” researchers say in a new paper, “Carbonation of serpentinite in creeping faults of California,” published in Geophysical Research Letters.

The new study integrates field observations and thermodynamic modeling “to examine possible relationships between the occurrence of serpentinite, silica-carbonate rock, and CO2-rich aqueous fluids in creeping faults of California,” the paper states. “Our models predict that carbonation of serpentinite leads to the formation of talc and magnesite, followed by silica-carbonate rock. While abundant exposures of silica-carbonate rock indicate complete carbonation, serpentinite hosted CO2-rich spring fluids are strongly supersaturated with talc at elevated temperatures. Hence, carbonation of serpentinite is likely ongoing in parts of the San Andres Fault system and operates in conjunction with other modes of talc formation that may further enhance the potential for aseismic creep, thereby limiting the potential for large earthquakes.”

The paper indicates that because wet talc is a mechanically weak mineral, “its formation through carbonation promotes tectonic movements without large earthquakes.”

The researchers recognized several possible underlying mechanisms causing aseismic creep in the SAF, and they also noted that because the rates of aseismic creep are significantly higher in some parts of the SAF system, an additional or different mechanism – the carbonation of serpentinite – is needed to account for the full extent of the creep.

With fluids basically everywhere along the SAF, but with only certain portions of the fault being lubricated, researchers considered that a rock could be responsible for the lubrication. Some earlier studies had suggested that the lubricant could be talc, a soft and slippery component that is commonly used in baby powder. A well-established mechanism for forming talc is by adding silica to mantle rocks. However, the researchers here focused on another talc-forming mechanism: adding CO2 to mantle rocks to form soapstone.

“The addition of CO2 to mantle rocks  – which is the mineral carbonation or carbon sequestration process – had not previously been investigated in the context of earthquake formation or the natural prevention of earthquakes. Using basic geological constraints, our study showed where these carbonate-altered mantle rocks are and where there are springs along the fault line in California that are enriched in CO2. It turned out that when you plot the occurrence and distribution of these rock types and the occurrence of CO2-rich springs in California, they all line up along the San Andreas Fault in creeping sections of the fault where you don’t have major earthquakes,” said Frieder Klein, lead author of the journal article.

Klein, an associate scientist in the Marine Chemistry and Geochemistry Department at the Woods Hole Oceanographic Institution, explained that carbonation is basically the uptake of CO2 by a rock. Klein noted that he had used existing U.S. Geological Survey databases and Google Earth to plot the locations of carbonate-altered rocks and CO2-rich springs.

“The geological evidence suggests that this mineral carbonation process is taking place and that talc is an intermediary reaction product of that process,” Klein said. Although researchers did not find soapstone on mantle rock outcrops, results from theoretical models “strongly suggest that carbonation is an ongoing process and that soapstone indeed could form in the SAF at depth,” the paper notes.  

These theoretical models “suggest that carbon sequestration with the SAF is taking place today and that the process is actively helping to lubricate the fault and minimize strong earthquakes in the creeping portions of the SAF,” Klein said.

The paper also notes that this mechanism may also be present in other fault systems. “Because CO2-rich aqueous fluids and ultramafic rocks are particularly common in young orogenic belts and subduction zones, the formation of talc via mineral carbonation may play a critical role in controlling the seismic behavior of major tectonic faults around the world.”

“Our study allows us to better understand the fundamental processes that are taking place within fault zones where these ingredients are present, and allows us to better understand the seismic behavior of these faults, some of which are in densely populated areas and some of which are in lightly populated or oceanic settings,” Klein said.

This work was supported by grants from the National Science Foundation.

 

Authors: Frieder Klein1*, David L. Goldsby2, Jian Lin1, Muriel Andreani3

Affiliations:

1Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA

2University of Pennsylvania, Department of Earth and Environmental Sciences, Philadelphia, PA, USA

3Laboratoire de Géologie de Lyon, UMR 5276, ENS et Université Lyon 1, 69622 Villeurbanne Cedex, France

*corresponding author

 

About Woods Hole Oceanographic Institution

The Woods Hole Oceanographic Institution (WHOI) is a private, non-profit organization on Cape Cod, Massachusetts, dedicated to marine research, engineering, and higher education. Established in 1930, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate an understanding of the ocean’s role in the changing global environment. WHOI’s pioneering discoveries stem from an ideal combination of science and engineering—one that has made it one of the most trusted and technically advanced leaders in basic and applied ocean research and exploration anywhere. WHOI is known for its multidisciplinary approach, superior ship operations, and unparalleled deep-sea robotics capabilities. We play a leading role in ocean observation and operate the most extensive suite of data-gathering platforms in the world. Top scientists, engineers, and students collaborate on more than 800 concurrent projects worldwide—both above and below the waves—pushing the boundaries of knowledge and possibility. For more information, please visit www.whoi.edu

FOR PROFIT HEALTHCARE U$A

Men in same-sex couples suffer earnings decline when preventative HIV-medicine is available

Research on employer-sponsored health insurance bears implications across the labor market

Peer-Reviewed Publication

RENSSELAER POLYTECHNIC INSTITUTE

TROY, N.Y. — When expensive medicines that are proven to prevent HIV acquisition are available through employer-sponsored health insurance (ESI), annual earnings for men in same-sex couples decline and part-time employment increases. The labor market effects are largest for young white men, who are among those most likely to be taking HIV prevention drugs.

These are among the findings in a study published recently in Economics and Human Biology by Dr. Conor Lennon, an associate professor of economics at Rensselaer Polytechnic Institute.

“Health insurance offered by employers is the most common source of coverage among working-age adults,” Dr. Lennon said. “However, it is a benefit that carries unexpected and far-reaching impacts.”

This is because the cost for employers in the United States to provide health insurance is determined by the medical expenditures of their employees, a practice known as experience rating. Employees who use more expensive providers, procedures, and prescriptions make it more expensive for their company to offer a health insurance benefit, either via changes in premiums or via the direct costs of self-insurance, creating an incentive to hire only the healthiest workers, all else equal.

Lennon’s research examines the impact of Truvada, a Pre-Exposure Prophylaxis (PrEP) drug that effectively prevents HIV acquisition. With an average cost of over $20,000 per year, the advent of Truvada in 2012 significantly increased the expected cost of employing men who have sex with men.

Dr. Lennon used a ten-year span of data from the American Community Survey of the United States Census Bureau and a difference-in-difference empirical approach to explore the possible impact of ESI on labor market outcomes for men in same-sex couples.

He found that when PrEP drugs became available, annual earnings for men in same-sex couples who have ESI declined by $2,650 (approximately 3.9%) relative to comparable men in different-sex couples.

When focusing on those working full-time, Dr. Lennon found a larger $3,013 relative decline in earnings.

Dr. Lennon also found a 0.8 percentage point (10.7%) increase in the proportion of men in same-sex couples working part-time, defined as fewer than 30 hours per week.

There were no comparable effects for women in same-sex couples.

“ESI clearly affects workers by sexual orientation which could also help to explain some of the historical wage penalty for gay and bisexual men,” Lennon said. “Moreover, given recent Federal Drug Administration approvals of increasingly expensive pharmaceuticals – such as Aduhelm for Alzheimer’s – future work should try to estimate how the costs of new medications impact the earnings and employment of those workers likely to need access to such expensive drugs.”

About Rensselaer Polytechnic Institute

Founded in 1824, Rensselaer Polytechnic Institute is America’s first technological research university. Rensselaer encompasses five schools, over 30 research centers, more than 140 academic programs including 25 new programs, and a dynamic community made up of over 6,800 students and 104,000 living alumni. Rensselaer faculty and alumni include upwards of 155 National Academy members, six members of the National Inventors Hall of Fame, six National Medal of Technology winners, five National Medal of Science winners, and a Nobel Prize winner in Physics. With nearly 200 years of experience advancing scientific and technological knowledge, Rensselaer remains focused on addressing global challenges with a spirit of ingenuity and collaboration. To learn more, please visit www.rpi.edu.

Contact: 

Christian TeBordo

Sr. Communications Specialist

tebordc@rpi.edu

 

Tracey Leibach

Director, Periodicals

leibat@rpi.edu

For general inquiries: newsmedia@rpi.edu

Visit the Rensselaer research and discovery blog: https://everydaymatters.rpi.edu/

Follow us on Twitter: @RPINews

---

JOURNAL

Economics & Human Biology

DOI

10.1016/j.ehb.2022.101156 

ARTICLE TITLE

Employer-sponsored health insurance and labor market outcomes for men in same-sex couples: Evidence from the advent of pre-exposure prophylaxisROFIT H

Men in same-sex couples suffer earnings decline when preventative HIV-medicine is available

Research on employer-sponsored health insurance bears implications across the labor market

Peer-Reviewed Publication

RENSSELAER POLYTECHNIC INSTITUTE

TROY, N.Y. — When expensive medicines that are proven to prevent HIV acquisition are available through employer-sponsored health insurance (ESI), annual earnings for men in same-sex couples decline and part-time employment increases. The labor market effects are largest for young white men, who are among those most likely to be taking HIV prevention drugs.

These are among the findings in a study published recently in Economics and Human Biology by Dr. Conor Lennon, an associate professor of economics at Rensselaer Polytechnic Institute.

“Health insurance offered by employers is the most common source of coverage among working-age adults,” Dr. Lennon said. “However, it is a benefit that carries unexpected and far-reaching impacts.”

This is because the cost for employers in the United States to provide health insurance is determined by the medical expenditures of their employees, a practice known as experience rating. Employees who use more expensive providers, procedures, and prescriptions make it more expensive for their company to offer a health insurance benefit, either via changes in premiums or via the direct costs of self-insurance, creating an incentive to hire only the healthiest workers, all else equal.

Lennon’s research examines the impact of Truvada, a Pre-Exposure Prophylaxis (PrEP) drug that effectively prevents HIV acquisition. With an average cost of over $20,000 per year, the advent of Truvada in 2012 significantly increased the expected cost of employing men who have sex with men.

Dr. Lennon used a ten-year span of data from the American Community Survey of the United States Census Bureau and a difference-in-difference empirical approach to explore the possible impact of ESI on labor market outcomes for men in same-sex couples.

He found that when PrEP drugs became available, annual earnings for men in same-sex couples who have ESI declined by $2,650 (approximately 3.9%) relative to comparable men in different-sex couples.

When focusing on those working full-time, Dr. Lennon found a larger $3,013 relative decline in earnings.

Dr. Lennon also found a 0.8 percentage point (10.7%) increase in the proportion of men in same-sex couples working part-time, defined as fewer than 30 hours per week.

There were no comparable effects for women in same-sex couples.

“ESI clearly affects workers by sexual orientation which could also help to explain some of the historical wage penalty for gay and bisexual men,” Lennon said. “Moreover, given recent Federal Drug Administration approvals of increasingly expensive pharmaceuticals – such as Aduhelm for Alzheimer’s – future work should try to estimate how the costs of new medications impact the earnings and employment of those workers likely to need access to such expensive drugs.”

About Rensselaer Polytechnic Institute

Founded in 1824, Rensselaer Polytechnic Institute is America’s first technological research university. Rensselaer encompasses five schools, over 30 research centers, more than 140 academic programs including 25 new programs, and a dynamic community made up of over 6,800 students and 104,000 living alumni. Rensselaer faculty and alumni include upwards of 155 National Academy members, six members of the National Inventors Hall of Fame, six National Medal of Technology winners, five National Medal of Science winners, and a Nobel Prize winner in Physics. With nearly 200 years of experience advancing scientific and technological knowledge, Rensselaer remains focused on addressing global challenges with a spirit of ingenuity and collaboration. To learn more, please visit www.rpi.edu.

Contact: 

Christian TeBordo

Sr. Communications Specialist

tebordc@rpi.edu

 

Tracey Leibach

Director, Periodicals

leibat@rpi.edu

For general inquiries: newsmedia@rpi.edu

Visit the Rensselaer research and discovery blog: https://everydaymatters.rpi.edu/

Follow us on Twitter: @RPINews

---

JOURNAL

Economics & Human Biology

DOI

10.1016/j.ehb.2022.101156 

ARTICLE TITLE

Employer-sponsored health insurance and labor market outcomes for men in same-sex couples: Evidence from the advent of pre-exposure prophylaxis