Background
Wildfires in the Pacific Northwest (Washington, Oregon, Idaho, and western Montana, USA) have been immense in recent years, capturing the attention of resource managers, fire scientists, ...and the general public. This paper synthesizes understanding of the potential effects of changing climate and fire regimes on Pacific Northwest forests, including effects on disturbance and stress interactions, forest structure and composition, and post-fire ecological processes. We frame this information in a risk assessment context, and conclude with management implications and future research needs.
Results
Large and severe fires in the Pacific Northwest are associated with warm and dry conditions, and such conditions will likely occur with increasing frequency in a warming climate. According to projections based on historical records, current trends, and simulation modeling, protracted warmer and drier conditions will drive lower fuel moisture and longer fire seasons in the future, likely increasing the frequency and extent of fires compared to the twentieth century. Interactions between fire and other disturbances, such as drought and insect outbreaks, are likely to be the primary drivers of ecosystem change in a warming climate. Reburns are also likely to occur more frequently with warming and drought, with potential effects on tree regeneration and species composition. Hotter, drier sites may be particularly at risk for regeneration failures.
Conclusion
Resource managers will likely be unable to affect the total area burned by fire, as this trend is driven strongly by climate. However, fuel treatments, when implemented in a spatially strategic manner, can help to decrease fire intensity and severity and improve forest resilience to fire, insects, and drought. Where fuel treatments are less effective (wetter, high-elevation, and coastal forests), managers may consider implementing fuel breaks around high-value resources. When and where post-fire planting is an option, planting different genetic stock than has been used in the past may increase seedling survival. Planting seedlings on cooler, wetter microsites may also help to increase survival. In the driest topographic locations, managers may need to consider where they will try to forestall change and where they will allow conversions to vegetation other than what is currently dominant.
Sexual Dimorphism in Colon Cancer Abancens, Maria; Bustos, Viviana; Harvey, Harry ...
Frontiers in oncology,
12/2020, Letnik:
10
Journal Article
Recenzirano
Odprti dostop
A higher incidence of colorectal cancer (CRC) is found in males compared to females. Young women (18-44 years) with CRC have a better survival outcome compared to men of the same age or compared to ...older women (over 50 years), indicating a global incidence of sexual dimorphism in CRC rates and survival. This suggests a protective role for the sex steroid hormone estrogen in CRC development. Key proliferative pathways in CRC tumorigenesis exhibit sexual dimorphism, which confer better survival in females through estrogen regulated genes and cell signaling. Estrogen regulates the activity of a class of Kv channels (KCNQ1:KCNE3), which control fundamental ion transport functions of the colon and epithelial mesenchymal transition through bi-directional interactions with the Wnt/β-catenin signalling pathway. Estrogen also modulates CRC proliferative responses in hypoxia
the novel membrane estrogen receptor GPER and HIF1A and VEGF signaling. Here we critically review recent clinical and molecular insights into sexual dimorphism of CRC biology modulated by the tumor microenvironment, estrogen, Wnt/β-catenin signalling, ion channels, and X-linked genes.
The COVID-19 pandemic has been a global health crisis of unprecedented magnitude. In the battle against the SARS-CoV-2 coronavirus, dexamethasone, a widely used corticosteroid with potent ...anti-inflammatory properties, has emerged as a promising therapy in the fight against severe COVID-19. Dexamethasone is a synthetic glucocorticoid that exerts its therapeutic effects by suppressing the immune system and reducing inflammation. In the context of COVID-19, the severe form of the disease is often characterized by a hyperactive immune response, known as a cytokine storm. Dexamethasone anti-inflammatory properties make it a potent tool in modulating this exaggerated immune response. Lung inflammation may lead to excessive fluid accumulation in the airways which can reduce gas exchange and mucociliary clearance. Pulmonary oedema and flooding of the airways are hallmarks of severe COVID-19 lung disease. The volume of airway surface liquid is determined by a delicate balance of salt and water secretion and absorption across the airway epithelium. In addition to its anti-inflammatory actions, dexamethasone modulates the activity of ion channels which regulate electrolyte and water transport across the airway epithelium. The observations of dexamethasone activation of sodium ion absorption via ENaC Na
channels and inhibition of chloride ion secretion via CFTR Cl
channels to decrease airway surface liquid volume indicate a novel therapeutic action of the glucocorticoid to reverse airway flooding. This brief review delves into the early non-genomic and late genomic signaling mechanisms of dexamethasone regulation of ion channels and airway surface liquid dynamics, shedding light on the molecular mechanisms underpinning the action of the glucocorticoid in managing COVID-19.
Forest resilience to climate change is a global concern given the potential effects of increased disturbance activity, warming temperatures and increased moisture stress on plants. We used a ...multi‐regional dataset of 1485 sites across 52 wildfires from the US Rocky Mountains to ask if and how changing climate over the last several decades impacted post‐fire tree regeneration, a key indicator of forest resilience. Results highlight significant decreases in tree regeneration in the 21st century. Annual moisture deficits were significantly greater from 2000 to 2015 as compared to 1985–1999, suggesting increasingly unfavourable post‐fire growing conditions, corresponding to significantly lower seedling densities and increased regeneration failure. Dry forests that already occur at the edge of their climatic tolerance are most prone to conversion to non‐forests after wildfires. Major climate‐induced reduction in forest density and extent has important consequences for a myriad of ecosystem services now and in the future.
Wildfires across western North America have increased in number and size over the past three decades, and this trend will continue in response to further warming. As a consequence, the wildland–urban ...interface is projected to experience substantially higher risk of climate-driven fires in the coming decades. Although many plants, animals, and ecosystem services benefit from fire, it is unknown how ecosystems will respond to increased burning and warming. Policy and management have focused primarily on specified resilience approaches aimed at resistance to wildfire and restoration of areas burned by wildfire through fire suppression and fuels management. These strategies are inadequate to address a new era of western wildfires. In contrast, policies that promote adaptive resilience to wildfire, by which people and ecosystems adjust and reorganize in response to changing fire regimes to reduce future vulnerability, are needed. Key aspects of an adaptive resilience approach are (i) recognizing that fuels reduction cannot alter regional wildfire trends; (ii) targeting fuels reduction to increase adaptation by some ecosystems and residential communities to more frequent fire; (iii) actively managing more wild and prescribed fires with a range of severities; and (iv) incentivizing and planning residential development to withstand inevitable wildfire. These strategies represent a shift in policy and management from restoring ecosystems based on historical baselines to adapting to changing fire regimes and from unsustainable defense of the wildland–urban interface to developing fire-adapted communities. We propose an approach that accepts wildfire as an inevitable catalyst of change and that promotes adaptive responses by ecosystems and residential communities to more warming and wildfire.
Ecological memory is central to how ecosystems respond to disturbance and is maintained by two types of legacies -information and material. Species life-history traits represent an adaptive response ...to disturbance and are an information legacy; in contrast, the abiotic and biotic structures (such as seeds or nutrients) produced by single disturbance events are material legacies. Disturbance characteristics that support or maintain these legacies enhance ecological resilience and maintain a "safe operating space" for ecosystem recovery. However, legacies can be lost or diminished as disturbance regimes and environmental conditions change, generating a "resilience debt" that manifests only after the system is disturbed. Strong effects of ecological memory on post-disturbance dynamics imply that contingencies (effects that cannot be predicted with certainty) of individual disturbances, interactions among disturbances, and climate variability combine to affect ecosystem resilience. We illustrate these concepts and introduce a novel ecosystem resilience framework with examples of forest disturbances, primarily from North America. Identifying legacies that support resilience in a particular ecosystem can help scientists and resource managers anticipate when disturbances may trigger abrupt shifts in forest ecosystems, and when forests are likely to be resilient.
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There is increasing evidence for sexual dimorphism of estrogen (E2) actions in the exacerbation of lung function, infection and inflammation in females with cystic fibrosis - the ...so-called “CF gender gap”. The effects of estrogen on virulence factors that enhance P. aeruginosa persistence in CF lung epithelium were investigated by phenotypic and chemical assays in various PsA clinical isolates and laboratory strains in isolation or in co-culture with normal (Nuli-1) and CF dPhe508-CFTR (CuFi-1) human bronchial epithelial cell lines. Estrogen (E2, 10 nM) significantly increased secretion of the virulence factor pyocyanin by 80% in PsA early infection isolates from female CF patients and by 280% in late infection PsA isolates. Estrogen also increased the swarming motility by up to 50% in all PsA isolates and strains tested in 0.5% agar. A significant increase of 110% in the twitching motility of all PsA isolates and strains tested was also observed with estrogen treatment. Treatment with E2 increased biofilm formation of P. aeruginosa PsAO1 which became more adherent to, and invasive into, normal and CF bronchial epithelial cells. The selective estrogen receptor modulators (SERMs), Tamoxifen and ICI 182780 inhibited P. aeruginosa motility. The potency of various steroid hormones to stimulate motility of P. aeruginosa was in the order; estradiol ≫ estrone > E3 estriol ≥ testosterone ≥ progesterone ≫ aldosterone, cortisol. Estrogen was also shown to reduce ciliary beat intensity in CF bronchial epithelium which would further exacerbate PsA trapping and virulence in the CF airways. In conclusion, we have demonstrated for the first time that estrogen exacerbates P. aeruginosa virulence factors and enhances bacterial interactions with CF bronchial epithelium which can be inhibited by tamoxifen. Our work suggests that SERMs could be used as an adjuvant treatment to reduce estrogen-induced P. aeruginosa infections and associated lung exacerbations in females with CF.
Subalpine forests in the northern Rocky Mountains have been resilient to stand-replacing fires that historically burned at 100- to 300-year intervals. Fire intervals are projected to decline ...drastically as climate warms, and forests that reburn before recovering from previous fire may lose their ability to rebound. We studied recent fires in Greater Yellowstone (Wyoming, United States) and asked whether short-interval (< 30 years) stand-replacing fires can erode lodgepole pine (Pinus contorta var. latifolia) forest resilience via increased burn severity, reduced early postfire tree regeneration, reduced carbon stocks, and slower carbon recovery. During 2016, fires reburned young lodgepole pine forests that regenerated after wildfires in 1988 and 2000. During 2017, we sampled 0.25-ha plots in stand-replacing reburns (n = 18) and nearby young forests that did not reburn (n = 9). We also simulated stand development with and without reburns to assess carbon recovery trajectories. Nearly all prefire biomass was combusted (“crown fire plus”) in some reburns in which prefire trees were dense and small (≤4-cm basal diameter). Postfire tree seedling density was reduced sixfold relative to the previous (long-interval) fire, and high-density stands (>40,000 stems ha−1) were converted to sparse stands (< 1,000 stems ha−1). In reburns, coarse wood biomass and aboveground carbon stocks were reduced by 65 and 62%, respectively, relative to areas that did not reburn. Increased carbon loss plus sparse tree regeneration delayed simulated carbon recovery by > 150 years. Forests did not transition to nonforest, but extreme burn severity and reduced tree recovery fore-shadow an erosion of forest resilience.
Increasing evidence indicates that forest disturbances are changing in response to global change, yet local variability in disturbance remains high. We quantified this considerable variability and ...analyzed whether recent disturbance episodes around the globe were consistently driven by climate, and if human influence modulates patterns of forest disturbance. We combined remote sensing data on recent (2001-2014) disturbances with in-depth local information for 50 protected landscapes and their surroundings across the temperate biome. Disturbance patterns are highly variable, and shaped by variation in disturbance agents and traits of prevailing tree species. However, high disturbance activity is consistently linked to warmer and drier than average conditions across the globe. Disturbances in protected areas are smaller and more complex in shape compared to their surroundings affected by human land use. This signal disappears in areas with high recent natural disturbance activity, underlining the potential of climate-mediated disturbance to transform forest landscapes.
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