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Comparative Evaluation of Toxicity End Points in Unicellular Bioassays for Environmental Pollutant Assessment
Get PDFAquatic environments contain mixtures of contaminants, of which many cannot be detected through conventional chemical monitoring. Effect-directed analysis (EDA) uses bioassays to detect bioactive compounds and relies on sensitive small volume assays. The aim of this study was to evaluate the sensitivity of three unicellular species (Raphidocelis subcapitata, Escherichia coli, and Saccharomyces cerevisiae) and five vertebrate cell lines to 21 chemicals with diverse modes of action. The algae assay exhibited the highest sensitivity, detecting toxicity in >80% of the chemicals, while yeast was the least responsive. Subsequently, 279 wastewater samples were screened using algae and three cell lines. Algae detected toxicity in >92% of the samples, while the cell line viability assays responded to 21-53% of the samples. Bioavailability modeling revealed that medium composition significantly influenced chemical partitioning. Algae assays that performed in protein- and lipid-free medium were more sensitive to lipophilic compounds than assays using heterotrophic cells. We hypothesize that medium-driven differences in bioavailability contribute to the higher sensitivity of algae, even to pharmaceuticals with no known algal targets. Combining algae and DR-EcoScreen cell assays captured 96.4% of detected toxicities in environmental samples. This combination offers a high-throughput, cost-effective strategy for screening environmental samples for bioactive substance
Phenotypic variation in otolith shape of American shad across eastern North American rivers
Get PDFOtolith shape analysis has been widely applied to study population structure and environmental influences in various fish species. However, research on American shad (Alosa sapidissima) otolith morphology remains scarce, despite its potential to provide insights into population differentiation and environmental adaptation. This study analyses otolith contour shape from 1141 American shad collected between 2000 and 2023 across eleven large rivers from Canada to Florida. Using a wavelet transform framework based on the & agrave; trous algorithm and B3-spline wavelet, we quantified otolith shape variability and assessed its effectiveness for population discrimination. Principal Component Analysis revealed significant shape variation, with key differences in the rostrum, antirostrum, and posterior region. Wavelet analysis identified two primary otolith morphologies-upper and lower rostrum-geographically structured along a latitudinal gradient. A Multilayer Perceptron neural network successfully classified individuals with 90.9% accuracy, highlighting strong population differentiation, particularly in the St. Lawrence and Delaware rivers. Cluster analysis identified five morphotypes with distinct spatial distributions, suggesting a role for local environmental conditions in shaping otolith morphology. These findings underscore the utility of otolith shape analysis in deciphering population structure and highlight potential links between environmental variation and phenotypic plasticity in American shad
Global forest carbon leakage and substitution effect potentials: The case of the Swedish forest sector
Get PDFThe forest sector's climate change mitigation depends on forest carbon sequestration, storing carbon in wood products, and avoidance of fossil greenhouse gas emissions by replacing more emission intensive products or energy sources, i.e., the substitution effect. In addition, market responses to changes in wood supply following altered forest management by one region induce climate relevant changes in form of compensatory roundwood harvest outside the region, and thus forest carbon leakage. This study presents a global climate change mitigation assessment of the forest sector, accounting for market-effects leakage. We use a global forest sector model, wood flow analysis and life cycle inventory data to assess the impact of forest management changes on climate change mitigation, with a focus on Sweden. Results suggest decreased wood harvesting causes global net climate change mitigation until 2070, despite forest carbon leakage, forgone wood product carbon storage and forgone substitution effect potentials. Increasing domestic wood removals induces global additional emissions until 2100. Additional domestic wood product consumption is climate beneficial which however depends on substitution effects actually materializing. Roundwood harvest leakage ranges from 40 % to 60 % and forest carbon leakage from 50 % to 80 %. Leakage effects occur mainly in North America and Asia, with a gradual shift towards Latin America over time. To further the climate benefit, drivers of growing demand should be addressed and measures be implemented which promote more efficient and sustainable use of wood as a resource. Only concerted global forest policy cooperation would avoid leakage and with that result in improved global climate change mitigation
Uptake of Gaseous Elemental Mercury by a Rainforest: Insights from a Tropical Glasshouse Used as a Dynamic Flux Chamber
Get PDFVegetation uptake of gaseous elemental mercury (Hg-0) is the main deposition pathway to terrestrial environments. However, the fluxes and processes of forest-atmosphere Hg-0 exchange remain ill-constrained, especially in rainforests. To help address this, we used the 1 ha Masoala Rainforest hall of the Zoo Zurich as a dynamic flux chamber to measure net rainforest Hg-0 fluxes and even calibrate Hg-0 deposition velocities with turbulence measurements. The net Hg-0 flux correlated well with CO2 assimilation, showing peak Hg-0 uptake at noon. The interquartile range of Hg-0 uptake spanned from 1.69 to 3.45 ng m(-2) h(-1) during the day and from 0.01 to 0.44 ng m(-2) h(-1) at night. The study results revealed a Hg-0-specific canopy resistance (R-c = 1000 s m(-1)), which underlined the importance of stomatal uptake as a dominant Hg-0 deposition pathway in the rainforest. Even though a dynamic flux chamber, however large, is only an approximation of a real rainforest, our findings underline the value of whole-rainforest flux studies both for constraining Hg exchange with the atmosphere and resolving the role of specific mechanisms
Trends in hydroclimate extremes: how changes in winter affect water storage and baseflow
Get PDFNorthern ecosystems are undergoing accelerated climate warming, with average temperature increases exceeding the global mean. In snow-dominated catchments, where cold-season conditions are essential for sustaining streamflow across subsequent seasons, substantial uncertainty persists regarding the impacts of future warming on catchment water storage and runoff dynamics. Here, we utilized 40 years of hydrological data from the boreal Krycklan Catchment, set within a 130-year climate record from a nearby station, to evaluate how 27 extreme climate indices can capture changes and trends in water storage and stream low flow during winter and summer. Our results show that annual temperatures have risen by 2.2 degrees C over the past 4 decades, with even more pronounced seasonal impacts. Notably, six winter extreme indices and two summer indices revealed distinct trends. We found that warm winters have led to increased winter stream runoff but reduced summer runoff. Predictive modelling indicated that the accumulated freezing degree days ( AFDD < 0 ) were the strongest predictor of minimum winter flow, while a combination of AFDD < 0 and maximum summer temperature (Max T-max ) best explained variations in minimum summer flow. Furthermore, analysis of streamflow partitioning using water isotopes and the seasonal origin index (SOI) over the past 22 years revealed an increasing winter precipitation signal in winter runoff, accompanied by a declining contribution to summer streamflow. Together, these findings demonstrate that warm winters are fundamentally altering catchment-scale water storage and flow partitioning, with important implications for water availability and ecosystem functioning during the growing season in boreal landscapes
Gene expression profiling in cardiac tissue of mice chronically infected with Toxoplasma gondii: implications for immune response pathways
Get PDFToxoplasma gondii is a common and opportunistic protozoan in vertebrates. Most cases of infection are asymptomatic, but in individuals with an immune system deficiency, it can cause severe complications. The parasite has the ability to form cysts in the host's heart, brain, and other tissues. Heart tissue damage during toxoplasmosis infection is associated with many complications, such as myocarditis, pericarditis, arrhythmia and heart failure. The parasite can survive and create a chronic form of infection by changing the expression of genes effective in the immune system. Therefore, the present study aims to investigate expression dynamics of candidate genes in the heart tissue of mice infected with the chronic T. gondii strain of Tehran and the pathways involved. After causing toxoplasmosis infection in mice and confirming the infection by MAT, RNA was extracted from the heart tissue of mice and converted into cDNA. Then, real-time PCR was performed to check the expression changes based on the designed primers of the target genes, and pathway analysis was performed. The results of real-time PCR analysis showed that all candidate genes have a higher expression in infected heart tissue compared to non-infected heart tissue. In addition, gene ontology and pathway analysis revealed that the cytosolic DNA-sensing pathway and autoimmune thyroid illness had the most gene participation
Establishment and management of planted birch
Get PDFSilver birch (Betula pendula Roth) has traditionally played a secondary role in Swedish forestry, dominated by coniferous species such as Norway spruce (Picea abies L.) and Scots pine (Pinus sylvestris L.). However, the increasing need for more diversified and climate-resilient forestry, combined with the availability of genetically improved planting material through breeding programmes, has renewed interest in birch as a viable alternative. This thesis investigated key aspects of establishing and managing planted silver birch, with a particular focus on spacing, browsing by cervids, thinning strategies, and modelling growth of genetically improved material. The research questions were explored through short-term field trials, long-term experiments, and surveys in Sweden and Latvia, complemented by interviews with private forest owners in Sweden. Establishment-related results showed that diameter growth increases with wider spacing. Yet, higher initial density may also serve as a tool to manage the local browsing risk. Light-to-moderate browsing did not significantly reduce survival or height growth of silver birch, indicating on species’ ability to compensate for early-stage browsing. However, the negative impact of browsing on tree quality suggests that protective measures depending on browsing risk are required. Management-related results demonstrated that heavy thinning resulted in the strongest individual tree diameter growth, albeit at the cost of total stand volume production. Furthermore, simulations of basal area development under varying levels of genetic gain revealed that improved material can substantially enhance stand productivity and reduce rotation length of planted silver birch stands. Overall, this thesis demonstrated that silver birch can be a viable alternative in Swedish forestry, offering high growth potential and resilience to browsing when properly managed. Thinning can further increase stand value by promoting high-quality timber, provided this aligns with the management goals
Climate Backlash and Policy Dismantling: How Discursive Mechanisms Legitimised Radical Shifts in Swedish Climate Policy
Get PDFClimate backlash and policy dismantling, that is, the reversal of existing decarbonisation policies, can be observed in an increasing number of countries. Typically, policy change tends to be slow, while climate backlash can unfold quite fast. How is such rapid political change made possible? Here, we investigate the case of Sweden, where a newly elected government significantly revised and changed existing climate policies. This change was forecast to increase carbon emissions rather than reduce them and included the abolishment of existing policies. While this process, in hindsight, could thus be seen as policy dismantling, it was characterised by a highly ambiguous debate that portrayed the new climate political approach as superior and much more effective than previous governments' approaches, and there was little, if any, opposition to these changes. To understand how such radical political change was possible, we examine policy documents and political debates and identify the discursive mechanisms employed in its legitimation. Our findings suggest that the parties in government used a set of discursive mechanisms to speak to different climate political discourses-welfarism, liberalism and nationalism-simultaneously. This created an effect that we call discursive flipping, which is qualitatively different from discursive blending, and that appeased potential opposition from both the left and right. As part of this, the creation of epistemic confusion seemed particularly effective in disarming opposition. We argue that discursive mechanisms are useful conceptual tools to examine the discursive legitimation of radical policy change, here realised by rendering discourses so ambiguous that opposition became discursively difficult to uphold
Stridulation-like behaviour in the Red Wood ant (Formica rufa)
Get PDFInsects are known for communicating via sounds created by rubbing body parts, a behaviour referred to as stridulation. Red Wood ants (Formica rufa group) are not known to possess stridulatory organs and have historically been categorised as a non-stridulating species. In this exploratory study, we report that Red Wood ants generate stridulation-like sounds, being about 0.7 +/- 0.2 seconds-long (mean +/- standard deviation), rattling sounds that were repeatedly generated in our laboratory setting (about 0.6 productions h-1 individual-1). In addition, we assess Red Wood ant behavioural responses to playbacks of this stridulation-like sound. Our playback experiments show that the stridulation-like sound initiates a reduced locomotory speed among conspecifics, an effect not seen when the ants were exposed to silence. However, this response was not different from that generated by an artificial pure tone, making the use of this stridulation-like sound uncertain. We hypothesise that the stridulation-like sound is produced by rubbing the leg against a ridge structure located on the anterior margin of the pronotum, a structure that we describe using X-ray micro-tomography. Our exploratory study suggests that the recorded sound may be part of Formica ant communication that is hard to detect and easily missed in behavioural assays
View Quality Assessments: A Pilot Study of Field Methods
Get PDFThis paper describes findings from a workshop during which participants evaluated a series of window views. An explorative approach was applied to identify issues and testing methods useful in daylight research. The participants visited nine rooms with views of varied content, complexity, and viewing distance under the overcast sky. Participants used surveys with quantitative and qualitative questions, hand drawings, illuminance measurements, and photography to appraise the view quality. Subsequently, daylight simulations and neurocognitive tests have been carried out in two rooms with "bad" and "good" views. Multi-directional views were valued more than narrow or single-directional views. The cognitive testing showed numerical differences in several measures and a significant correlation between the difference scores for sadness and the difference scores for Trail Making Test-B across two rooms. The study identified that buildings of historical value, a presence of greenery, colored building facades, or a presence of people (content) contribute to a positive assessment of the view but are not included in the assessment criteria