Roads, development disrupt movement of young mountain lions in California

Human barriers compromise movement, gene flow required for healthy populations

University of Nebraska-Lincoln

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Postdoctoral researcher Kyle Dougherty (left) and John Benson, associate professor at the University of Nebraska-Lincoln School of Natural Resources, found young mountain lions in California struggle to disperse between populations, which limits gene flow needed to keep populations healthy. 

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Credit: Jordon Opp | University Communication and Marketing | University of Nebraska-Lincoln

Previous research set off alarm bells by showing that mountain lion populations across California are more different genetically than normal for a wide-roaming predator. New findings published Dec. 3 in Frontiers in Ecology and the Environment have provided an explanation. A team of researchers has found that young mountain lions avoid highly developed areas and crossing busy roads as they navigate between populations seeking breeding territories in the Golden State.

The team tracked 87 "subadult" mountain lions with GPS collars to evaluate their ability to successfully move between different populations. Subadults are mountain lions from about 1 to 3 years old, recently independent of their mothers and trying to make it on their own in a difficult world. Through a process ecologists call "dispersal," they often move large distances seeking natural habitat to establish breeding ranges

“Long-distance dispersal by subadults is the key to maintaining connectivity between different mountain lion populations,” said Kyle Dougherty, a postdoctoral researcher at the University of Nebraska–Lincoln and lead author of the study. “When connectivity is disrupted and populations become isolated, it can result in reduced genetic diversity and population decline.”

Data from young, dispersing mountain lions is relatively rare. As a result, many studies evaluate connectivity by studying movements of adult, resident animals — which do not typically move between populations.

“Our findings suggest that human infrastructure like roads and development are inhibiting the ability of subadults to move through the landscape, access good habitat and connect populations genetically and demographically,” Dougherty said. “All of these things are essentially prerequisites for keeping mountain lion populations healthy at the statewide level.”

Isolated populations in southern California and along the central coast exhibit much lower genetic diversity than mountain lion populations in most states. The new research confirms what ecologists suspected previously — that this is likely the result of human infrastructure creating barriers to animal movement. The smallest populations in greater Los Angeles are threatened by local extinction due to isolation by large freeways and development. However, California is also home to larger, genetically diverse mountain lion populations in vast stretches of remote natural habitat, like those in the Sierra Nevada Mountains.

“Ideally, populations in the Sierras and northern California should act as sources of dispersing animals that occasionally bring themselves and their genes to distant populations,” said co-author John Benson, associate professor in the School of Natural Resources. “Our work suggests that large roads and extensive development limit the ability of large, healthy populations to maintain smaller, isolated populations as occurs in more natural settings.”

The new research is a key piece of the puzzle for conserving mountain lions in California. The species is being considered by state officials for listing under the California Endangered Species Act due to concerns about fractured connectivity, which may threaten the long-term viability of populations in southern California and along the central coast. The team generated a detailed map showing the ease, or difficulty, with which dispersing mountain lions move throughout every portion of the state. 

“The map is a direct reflection of the decisions that subadult mountain lions make as they move through the landscape,” Benson said. “It highlights critical linkages needed to maintain movement of mountain lions and their genes between populations and will inform conservation strategies to restore connectivity to this fragmented landscape.”

Some of the findings provided reason for optimism. Young mountain lions were capable of using even small patches of forest and shrub as "stepping stones" that may allow them to eventually reach larger patches of habitat needed to establish a breeding range. This shows the adaptability of these large cats as they navigate highly fragmented landscapes dominated by humans that lie between remote, rugged tracts of natural habitat in California where mountain lions can thrive.

“Our work supports previous suggestions that mountain lions can traverse inhospitable landscapes as long as there are remnant patches of forest that can act as corridors through urban sprawl,” Dougherty said. “However, the ubiquity of freeways and other large roads throughout California presents barriers to movement that may require implementation of wildlife crossing structures to maintain movement of young animals between populations.”

The new study helps to identify optimal locations for those structures. The team is currently working on integrating these new results, along with many years of behavioral, mortality, reproductive and genetic data, into a larger effort to understand the statewide population dynamics of mountain lions in California.

The research was a collaborative effort involving researchers from the California Department of Fish and Wildlife; University of California, Davis; University of California, Santa Cruz; National Park Service; True Wild; Institute for Wildlife Studies; All Hands Ecology; Victoria University of Wellington; Integral Ecology Research Center; and University of Nebraska–Lincoln.

A mountain lion overlooks a city. 

Credit

Courtesy: National Park Service

Journal

Frontiers in Ecology and the Environment

DOI

10.1002/fee.70020 

Method of Research

Observational study

Subject of Research

Animals

Article Title

Movement decisions reflect compromised statewide connectivity for mountain lions in California

Article Publication Date

3-Dec-2025

 

Vitamin C from food boosts collagen levels in skin – landmark study

University of Otago

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A breakthrough study from researchers at the University of Otago, Faculty of Medicine – Christchurch Ōtautahi, has found that collagen production and skin renewal directly respond to the amount of vitamin C we eat.  

The study, published in the international Journal of Investigative Dermatology, shows that skin vitamin C levels are closely tied to levels of the vitamin in the blood (plasma) and can be boosted by increasing fruit intake.  

Carried out on two dozen healthy adults in both Aotearoa New Zealand and Germany, the study shows that boosting plasma levels by consuming two vitamin C-rich SunGoldTM kiwifruit per day increases the amount of the vitamin in the skin, improving skin thickness (collagen production) and stimulating renewal and regeneration of the outer skin layer.  

Lead author, Professor Margreet Vissers from Mātai Hāora – Centre for Redox Biology and Medicine, within the Department of Pathology and Molecular Medicine, says the strength of the association between skin thickness and vitamin C intake is “compelling”. 

“We were surprised by the tight correlation between plasma vitamin C levels and those in the skin – this was much more marked than in any other organ we have investigated,” Professor Vissers says. 

“We are the first to demonstrate that vitamin C in the blood circulation penetrates all layers of the skin and is associated with improved skin function. I am very proud of my team and excited about what the data is telling us.” 

Professor Vissers says the study results suggest that beauty really does come from within, supporting your skin function from the inside-out by delivering vitamin C to the skin the way nature designed it – via the bloodstream.  

“We know that vitamin C is required for collagen production. This fact has inspired the addition of vitamin C to many skin cream formulations. However, vitamin C is highly water soluble and poorly absorbed through the outer skin barrier. Our study shows that the skin is extremely good at absorbing vitamin C from the blood circulation. Uptake into the outer epidermal skin layer also seems to be prioritised,” she says. 

Funded by New Zealand company Zespri International along with a University of Otago Research Grant, the study comprised two stages. The first stage established the association between plasma and skin vitamin C levels, using healthy skin tissue from patients undergoing elective surgical procedures at Te Whatu Ora Canterbury (with support from the Otago campus’s He Taonga Tapu - Canterbury Cancer Society Tissue Bank).  

The second stage involved a before-and-after, dietary vitamin C intervention study at two sites (in Christchurch and Germany), each with 12 healthy participants.  

“All were instructed to consume two Kiwi Gold kiwifruit daily - the equivalent of 250 micrograms of vitamin C - for eight weeks. We then collected skin samples before and after the intervention, with separate analyses allowing us to look at the skin basal layers in Christchurch and the outer dermal skin layer and skin function tests in Germany,” Professor Vissers explains.  

The German participants were recruited and tested by the SGS Institute Fresenius in Hamburg – their lab having the technical ability to collect the outer dermal skin layer (the blister “roof”). The Institute measured skin sample regeneration - including ultrasound tested measures of skin thickness, elasticity UV protection and renewal of epidermal cells - giving a complete picture of skin function. 

“The other really substantial finding showed a significant increase in the participants’ skin thickness levels, reflecting collagen production and an upsurge in the regeneration of their epidermal cells, in other words skin renewal,” Professor Vissers says. 

 She says SunGoldTM kiwifruit was chosen for the trial due to its proven high vitamin C levels, but it’s anticipated that other foods rich in vitamin C, particularly fresh fruit and vegetables such as citrus, berry fruit, capsicums and broccoli, would have similar beneficial effects.  

“We suggest that increasing your dietary vitamin C intake will result in effective vitamin C uptake into all compartments of the skin,” Professor Vissers says. 

“The important thing is to keep your plasma levels optimal, which we know can be easily achieved in a healthy person with a vitamin C intake of around 250mg per day. The body however does not store the vitamin, so we recommend 5+ a day, every day, with one of those five being a high vitamin C food, as a good habit to cultivate.” 

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Journal

Journal of Investigative Dermatology

DOI

10.1016/j.jid.2025.10.587 

Method of Research

Experimental study

Subject of Research

People

Article Title

Improved Human Skin Vitamin C Levels and Skin Function after Dietary Intake of Kiwifruit: A High-Vitamin-C Food

 

New roadmap reveals how everyday chemicals and microbes interact to fuel antimicrobial resistance

Biochar Editorial Office, Shenyang Agricultural University

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Chemicals–microbiome interactions and antimicrobial resistance: a roadmap for prediction and interventions

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Credit: Ji Lu

A new perspective published in Biocontaminant outlines an urgent scientific roadmap for understanding how common chemicals interact with microbial communities to accelerate the global crisis of antimicrobial resistance. The work, led by Ji Lu from the University of Queensland, highlights why traditional single chemical experiments fail to capture the real drivers of resistance in natural and clinical environments.

“Chemicals rarely occur alone in the real world. They mix, react, and interact with diverse microbiomes in ways that can either amplify or suppress antimicrobial resistance,” said Dr Lu. “If we want to protect public health, we must understand these interactions and use that knowledge to guide smarter monitoring and regulation.”

The article summarizes emerging evidence that mixtures of pollutants such as antibiotics, disinfectants, metals, and microplastics can have unexpected combined effects that promote resistance even when each chemical is present at low levels. Diverse microbial communities can sometimes buffer these effects, but in other cases they create conditions that accelerate the spread of resistance genes.

To address these challenges, the study proposes a three part roadmap. The first step focuses on mechanistic discovery through high throughput experiments and genomic tools to identify how chemical mixtures interact and how bacterial traits influence their responses. The second step emphasizes predictive modelling that integrates chemical properties, microbial traits, and environmental conditions to forecast high risk combinations. The final step promotes translation of these insights into practical interventions including mixture based risk thresholds, targeted pollutant removal, and microbiome informed mitigation strategies for water treatment and environmental management.

Dr Lu emphasized that coordinated efforts among scientists, regulators, utilities, and clinicians will be essential. “Understanding chemical microbiome interactions will allow us to act proactively rather than reactively. This approach can reduce the emergence of resistance at its environmental sources and protect both ecosystems and human health.”

 

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Journal reference: Lu J. 2025. Chemicals–microbiome interactions and antimicrobial resistance: a roadmap for prediction and interventions. Biocontaminant 1: e009  

https://www.maxapress.com/article/doi/10.48130/biocontam-0025-0010  

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About Biocontaminant:
Biocontaminant is a multidisciplinary platform dedicated to advancing fundamental and applied research on biological contaminants across diverse environments and systems. The journal serves as an innovative, efficient, and professional forum for global researchers to disseminate findings in this rapidly evolving field.

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DOI

10.48130/biocontam-0025-0010 

Method of Research

News article

Subject of Research

Not applicable

Article Title

Chemicals–microbiome interactions and antimicrobial resistance: a roadmap for prediction and interventions

 

Scientists clarify how much metal in soil is “too much” for people and the environment​

New open access review explains which laboratory tools, models and tests best capture the true bioavailability of heavy metals in soil and how regulators worldwide are starting to use them.

Biochar Editorial Office, Shenyang Agricultural University

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Bioavailability of heavy metals in soil: a review of tools, models, and regulatory applications

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Credit: Willie J.G.M. Peijnenburg

Heavy metals in soil are often measured in bulk, but those totals can badly overestimate the real risk to crops, ecosystems and human health, according to a new scientific review. The article, published in Environmental and Biogeochemical Processes, explains that only a fraction of the metal present in soil is actually accessible to plants, microbes and people – a concept known as bioavailability.

“Metal pollution in soil is a genuine global concern, but decisions about food safety, clean‑up and land reuse need to be based on the portion of metals that organisms can really take up, not just on headline numbers,” said lead author Willie J G M Peijnenburg of Leiden University and the National Institute for Public Health and the Environment in the Netherlands. “Our goal was to translate decades of research into a practical toolbox that scientists, consultants and regulators can actually apply in the field.”

Why bioavailability matters

The review begins by outlining how soils become contaminated by metals such as cadmium, lead, zinc, copper and arsenic through industry, agriculture, waste disposal and urban development. Unlike many organic pollutants, these metals do not break down over time, yet their risk depends strongly on soil pH, mineral composition, organic matter, redox conditions and microbial activity.​

In many sites, high total metal concentrations coexist with relatively low biological exposure, because metals are tightly bound to soil particles or locked in mineral forms that organisms cannot easily access. In other places, modest total levels can still pose a problem if soil conditions make metals mobile and readily taken up by crops or soil life.​

Tools to measure the “accessible” fraction

To turn this complex chemistry into actionable data, the review synthesizes three main groups of methods: chemical extractants, biological assays and in situ passive samplers. Common chemical tests using solutions such as calcium chloride, DTPA or EDTA are widely used to estimate labile or potentially mobile metal pools, while more elaborate sequential extraction schemes divide metals into exchangeable, reducible, oxidizable and residual fractions.​

Plant growth tests, earthworm and springtail assays, and microbial and enzyme activity measurements then reveal which soil metals are actually taken up or cause toxicity under realistic exposure conditions. Passive tools such as diffusive gradients in thin films and ion‑exchange resins bridge the gap by measuring freely available or weakly bound metals directly in the soil environment over time.​

Models, machine learning and regulation

Beyond measurements, the paper reviews a suite of models that predict metal bioavailability from basic soil properties and site conditions, ranging from simple regression equations to mechanistic speciation codes and biotic ligand models. More recently, machine learning approaches such as random forests, support vector machines and neural networks have been used to map bioavailable cadmium or zinc in agricultural regions and to forecast metal levels in crops.​

Case studies from Europe, North America and China show how bioavailability‑based approaches can change real‑world decisions. Examples include using bioaccessibility tests to avoid unnecessary excavation at urban redevelopment projects, and combining extractants, plant uptake data and models to manage cadmium in rice‑growing areas more precisely.​

Toward harmonized, practical frameworks

A key contribution of the review is a decision tree that helps practitioners select appropriate tools based on soil type, contaminants of concern, data needs and regulatory context. The framework encourages combining chemical indicators with biological and modeling information in a “weight of evidence” approach, rather than relying on any single test.​

“Many countries are beginning to incorporate bioavailability into soil quality criteria, but methods and thresholds still differ widely between regions,” Peijnenburg said. “If we want risk assessments to be both protective and affordable, the next step is international harmonization, better field validation and more open data on bioavailable metal fractions.”​

Future directions

The review highlights emerging molecular and microbial tools, such as metagenomics, transcriptomics and whole‑cell biosensors, that can detect early biological responses to bioavailable metal exposure. It also points to hybrid modeling approaches that combine physics‑based speciation models with data‑driven machine learning to improve predictions under changing climate and land‑use conditions.​

Ultimately, the author argues that focusing on bioavailability can lead to smarter remediation, more realistic soil standards and better protection of food security and ecosystem health worldwide. By summarizing the strengths, limits and regulatory relevance of each tool, the article offers a roadmap for scientists and policymakers who need to decide how much metal in soil is “too much” in practice, not just on paper.​

 

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Journal reference: Peijnenburg WJGM. 2025. Bioavailability of heavy metals in soil: a review of tools, models, and regulatory applications. Environmental and Biogeochemical Processes 1: e011  

https://www.maxapress.com/article/doi/10.48130/ebp-0025-0011  

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About the Journal:

Environmental and Biogeochemical Processes is a multidisciplinary platform for communicating advances in fundamental and applied research on the interactions and processes involving the cycling of elements and compounds between the biological, geological, and chemical components of the environment. 

Follow us on Facebook, X, and Bluesky.  

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DOI

10.48130/ebp-0025-0011 

Method of Research

Literature review

Subject of Research

Not applicable

Article Title

Bioavailability of heavy metals in soil: a review of tools, models, and regulatory applications

Article Publication Date

1-Dec-2025