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A Meta-Regression of 18 Wildfire Chronosequences Reveals Key Environmental Drivers and Knowledge Gaps in the Boreal Nitrogen Balance
Get PDFClimate change has increased the size and frequency of wildfires across the boreal biome. Severe wildfires in boreal forests have been found to trigger shifts from evergreen to deciduous canopies, which has cascading effects on carbon and nitrogen cycling. Ecosystem productivity and carbon uptake in boreal forests are strongly linked with nitrogen, and Earth system models increasingly depend on our understanding of the nitrogen balance to predict post-fire carbon uptake. To investigate the post-fire boreal nitrogen balance, we combined a mass balance approach and literature synthesis to estimate rates of nitrogen accumulation and nitrogen inputs across a network of 18 boreal wildfire chronosequences that varied in both wildfire regime and post-fire canopy type, comprising 527 forest stands. We found that deciduous- or mixed-dominance boreal forests establishing after severe, stand-replacing fires had the highest nitrogen accumulation rates (15.7 +/- 3.8 kg ha-1 year-1), while evergreen-dominated forests establishing after surface- or mixed-severity fires had the lowest nitrogen accumulation rates (1.4 +/- 1.1 kg ha-1 year-1). Annual known inputs from nitrogen deposition and biological nitrogen fixation combined, estimated from published data, largely failed to explain the rate of nitrogen accumulation, particularly in deciduous or mixed-dominance forests establishing after stand-replacing fires, suggesting that the origins of most nitrogen in these forest types remain poorly understood. As the frequency of severe wildfires increases across the boreal biome and shifts toward deciduous canopies become more common, our study reveals a large knowledge gap in the resulting nitrogen balance that needs to be resolved in order to improve predictions of forest carbon uptake
Debondable wood adhesives based on Diels-Alder and Schiff base reactions
Get PDFThe wood industry relies heavily on thermosetting resins such as urea-formaldehyde, polyurethanes, and epoxies for the manufacturing of engineered wood products. While these adhesives offer strong mechanical performance and moisture resistance, their environmental and health impact raise concerns. Additionally, the irreversible nature of these cross-linked networks prevents efficient material separation and recovery at the product's end-of-life.Bio-based debondable adhesives, capable of undergoing controlled debonding under specific stimuli, present a promising solution to enable disassembly and recycling of multilayer wood products, improving their sustainability.In the initial phase of this research, efforts were directed towards modifying potato starch (St) with maleimide moieties (6-maleimidohexanoic acid, 6-MHA). Both suspension and solution methods were explored. Maleimide grafted St (St6MHA) synthesized via the solution method was selected for further study due to the higher degree of the starch’s hydroxyl groups substitution by 6-MHA and the lack of St granule structure preservation of the suspension method .Kraft lignin (KL) was functionalized with furan groups to enable the formation of a Diels–Alder (DA) network with St-6MHA. Experimental results confirmed the successful formation of a reversible DA network, which formed at 65 °C over 48 h and dissociated at 135 °C after 3 h. Blends of these materials were used to bond furfurylated beech veneer, achieving an average tensile strength of 5.00 ± 0.5 MPa. Controlled debonding was observed at 135 °C after 4 h, demonstrating the system’s potential for recyclability of wood products.In a final step, a Schiff base network was developed using dialdehyde starch (DAS), hexamethylene diamine (HMDA), and amino-functionalized carbon dots. The incorporation of carbon dots showed promise in accelerating the curing process and enhancing the mechanical strength of the DAS:HMDA adhesive system. A tensile strength of 3.96 ± 0.18 MPa was achieved after just 300 sec of pressing at 160 °C, highlighting its potential as a fast-curing, bio-based adhesive
Prevalence of tick-borne pathogens in feeding and questing Ixodes ricinus ticks from Southern Sweden
Get PDFIxodes ricinus, the most common tick species in Northern Europe, plays a significant role as a vector of several pathogens, with its geographical distribution expanding in recent years. In Southern Sweden, particularly in Region Sk & aring;ne County (referred to as Sk & aring;ne), the favorable climate and landscape conditions support extensive proliferation of I. ricinus. Despite Lyme borreliosis being common in this region and few annual cases of tickborne encephalitis (TBE) being reported, data on the circulation of tick-borne pathogens (TBPs) remain limited. This study molecularly investigated the presence of Anaplasma phagocytophilum, Babesia spp., Borrelia spp., and TBE virus (TBEV) in I. ricinus ticks (n = 1000). In detail, questing ticks (82 adults and 196 nymphs) were collected from vegetation in forest and meadow areas, while 581, 80 and 8 feeding adults were collected from 39 roe deer, 6 fallow deer and 1 moose, respectively. Additionally, 53 feeding adults were removed from domestic animals (42 from four dogs and 11 from one cat). The molecular analyses detected Anaplasma phagocytophilum, Borrelia spp., and Babesia spp. in 54 %, 24 %, 3.2 % of host-feeding ticks and in 0.40 %, 35 %, 3.6 % of questing ticks, respectively. In detail, for Borrelia and Babesia genera, the following species were detected: Borrelia miyamotoi, Borrelia afzelii, Borrelia garinii, Borrelia burgdorferi s.s., Babesia microti and Babesia venatorum. TBEV was not detected. Moreover, the relationship between the feeding duration of the roe deer-collected ticks and their PCRpositivity for Borrelia spp. and A. phagocytophilum was also modeled. The results showed a reduction in the probability of tick infection with Borrelia spp. as attachment time increased, supporting evidence that roe deer serum exerts a borreliacidal effect. This study highlights the presence of several zoonotic TBPs in Sk & aring;ne, emphasizing the need for a structured monitoring plan and preventive strategies within a One Health framework
Ecotoxicity of pollutants on soil nitrifiers under a climate change scenario
Get PDFSoil microorganisms are essential for soil functioning but face increasing stress due to e.g. pollution and climate change. Yet, a scientific basis for how to assess impacts of environmental stressors on soil microorganisms is lacking. Nitrification, the oxidation of ammonia via nitrite to nitrate, is a process commonly shared between ammonia oxidising archaea (AOA) and bacteria (AOB), and nitrite oxidising bacteria, primarily Nitrobacter (NIB) and Nitrospira (NIS). Although these guilds are suggested as indicators of soil functioning, little is known about their combined responses to stressors, especially to multiple stressors, and effects on associations between ammonia and nitrite oxidisers. This thesis aimed to determine how soil microorganisms, particularly nitrifiers, respond to single and multiple stressors, using a resistance and resilience framework. Soils were exposed to contamination of herbicides, polycyclic aromatic hydrocarbons (PAH), or copper (Cu), and to dryingrewetting cycles in meso- and microcosm experiments. The results show minimal herbicide effects, but PAH altered total prokaryotic, AOA and AOB community composition at high contamination levels, while Cu caused major decreases in ammonia oxidation and community shifts even at low contamination levels. Drying temporarily decelerated ammonia oxidation and altered AOA community composition, indicating low resistance. However, rewetting restored ammonia oxidation, indicating resilience, but caused persistent shifts in NIS community composition, suggesting low resistance and resilience. Network analysis revealed drought effects on co-associations between ammonia and nitrite oxidisers, which could suggest a destabilised interaction. Drought effects were influenced by soil properties and contamination legacy. While herbicides affected the subsequent responses of the nitrifier guilds to drought only marginally, PAH and Cu displayed moderate to strong legacy effects. Overall, the findings emphasise the importance to consider stressor effects on soil microorganisms and subsequent consequences for soil functioning and N fluxes under both single and multiple stressor scenarios
Low-Dose Salinomycin Alters Mitochondrial Function and Reprograms Global Metabolism in Burkitt Lymphoma
Get PDFSalinomycin (SAL), originally identified for its potent antibacterial properties, has recently garnered attention for its remarkable activity against a variety of cancer types. Beyond its direct cytotoxic effects on cancer cells, SAL can also enhance the efficacy of anti-CD20 immunotherapy in B-cell malignancies, both in vitro and in vivo. Despite these promising findings, the precise molecular mechanisms underlying SAL's anticancer action remain poorly understood. Here, we demonstrate that even at low concentrations (0.25-0.5 mM), SAL disrupts mitochondrial membrane potential and induces oxidative stress in Burkitt lymphoma. Further investigations uncovered that SAL shifts cellular metabolism from mitochondrial respiration to aerobic glycolysis. Additionally, metabolomic profiling identified SAL-induced arginine depletion as a key metabolic alteration. These findings provide new insights into SAL's multifaceted mechanisms of action and support its potential as an adjunctive therapy in cancer treatment
Älgstammens utveckling
Get PDFSLU har haft i uppdrag att leverera skattningar av älgstammens täthet till länsstyrelserna och till älgförvaltningsgrupperna sedan 2021; från och med jaktåret 2023/24 har SLU även i uppdrag att årligen sammanfatta den genomförda älgförvaltningen i siffror. Sedan den nya älgförvaltningen infördes jaktåret 2012/13 har älgstammen först minskat under tio år, men utvecklingen har nu vänt och älgstammen ökar återigen. Älgstammen uppgick till cirka 300 000 individer vid jaktstart hösten 2024. Knappt 57 000 individer fälldes, och jakten reducerade därmed stammen till cirka 240 000 älgar vid jaktsäsongens slut. Till detta kommer predation och annan dödlighet som inträffat efter att jakten inleddes. Trendbrottet förefaller vara en effekt av att jägarna reducerat de två senaste årens avskjutning kraftigt jämfört med tidigare. Allt tyder nu på att jägarna har ändrat sina jaktbeteenden. Avskjutningen har minskat, samtidigt som antalet rapporterade observationstimmar minskar. Detta antyder att jägarna tillbringar mindre tid med att jaga älg. Samtidigt minskar både andelen av stammen som skjuts under jaktsäsongen och andelen älgar som skjuts av dem som faktiskt ses under de inledande 30 dagarna av jakten. Jägarna väljer därmed aktivt att inte skjuta lika många av de älgar de ser, och den mest sannolika förklaringen till mönstren är att jägarna nu aktivt försöker vända nedgången i älgstammen som fanns under den inledande fasen efter att den nya älgförvaltningen infördes. Det illustreras även av att de tydligaste förändringarna finns för andelen vuxna hondjur som fälls, eftersom de vuxna hondjuren är viktigast för populationstillväxten. Oavsett vad man tycker om populationsmålen är minskade jaktinsatser problematiskt ur ett viltövervakningsperspektiv, då det sannolikt krävs fler observationstimmar insamlade vid jakt för att mäta tätheten med en viss osäkerhet vid låga tätheter jämfört med höga. Vidare finns det en risk att skattningar av tätheten huvudsakligen kommer baseras på data från jämförelsevis älgtäta områden, om jägarna avstår från att jaga på de mer älgglesa markerna. SLU utvärderar för närvarande vilka effekter de ändrade jaktbeteendena har på inventeringsunderlagen för skattningarna
Limited effects of UVBR on primary productivity and photosynthetic pigment composition in the Greenland Sea
Get PDFThe Arctic icescape currently undergoes major transformations along with anthropogenic perturbations and climate change. These changes are affecting phytoplankton community composition and primary productivity in a possibly synergistic manner. With less ice, the phytoplankton communities will experience elevated light conditions, and there is a need to understand how low-light adapted phytoplankton species react to changes in light composition including ultraviolet B radiation (UVBR 280-320 nm) exposure. We therefore look back two decades (May 2002) in order to expand the limited but necessary baseline for comparative field observations of primary productivity and phytoplankton pigment composition, comparing under ice to open water conditions, and UVBR exposure to shielded conditions. Along the East Greenland Current cruise transects we observed a large patchiness in primary productivity, with indications of under-ice blooms with chlorophyll a values up to 9.9 mu g l(-1), nitrate concentration < 0.1 mu M, and primary productivity of 11.7 mu g C l(-1) h(-1). Surprisingly, we only observed a minor effect of UVBR treatment on primary productivity, and we did not observe a difference in mycosporine-like amino acids (MAAs) in the plankton community samples at surface (2 m) and deeper (approx. 20 m) water depths. Due to its early onset of climate related effects, studies in the Arctic region may signal future changes of ecosystems at lower latitudes. This comprehensive dataset on primary productivity, UV-absorbing compounds (MAAs), and pigment composition could offer a valuable baseline for assessing ecological change. It can inform climate impact modelling, support long-term ecosystem monitoring, and hopefully guide future management strategies in this vulnerable marine environment
Genome-wide association mapping and transcriptional analysis uncover genetic determinants of minor tocopherols in rice seeds
Get PDFDespite the nutritional importance of tocopherols, current knowledge of the genetic architecture underlying the accumulation of minor tocopherols-gamma (gamma) and delta (delta)-in rice (Oryza sativa L.) grains remains limited. In this study, we investigated the genetic basis of gamma- and delta-tocopherol contents in rice using a genome-wide association study (GWAS) and post-GWAS analysis. Accordingly, 34,323 SNP markers were obtained from 179 genotypically diverse accessions of O. sativa. Minor tocopherol contents had a strong positive correlation (r = 0.76) with each other and varied greatly across the accessions: 0.015-1.74 and 0.005-0.81 (mu g/g) for gamma and delta, respectively. A total of 18 QTL on nine rice chromosomes were mapped. Eight transcription factor (TF) genes, five lncRNAs, and two transposons were found to be associated with the QTL. Moreover, three intracellular transport proteins were identified as associated genes with gamma-tocopherol on chromosomes 1, 2, and 6. Protein kinases seem to have a substantiative function in defining the minor tocopherol contents, as they were associated with all 18 identified QTL. Haplotype analysis revealed that the QTL, namely qDelt2.1, qGam2.1, and qGam6.1, can maintain significant haplogroups. Comparative transcript analysis between high and low-content minor tocopherols demonstrated the possible involvement of ERF71 (Os06g0194000), TOR (Os05g0235300) and NAC70 (Os02g0822400) in defining the minor tocopherol contents in rice. Identified candidate genes in this study could be used in breeding programs to develop rice cultivars with high and beneficial levels of seed tocopherol contents
Connectivity and Population Structure in a Marginal Sea-A Review
Get PDFAimThe current biodiversity crisis calls for conservation measures that limit or reduce the negative human impact on key habitats and vulnerable wild populations. To effectively protect biodiversity at all levels, including intra-specific diversity, conservation measures should, ideally, be aligned with the connectivity and genetic structure of wild populations. In this review, we synthesise the scientific literature on connectivity and population structure of marine species in a marginal sea.LocationThe study focuses on the Skagerrak-a marginal sea in the northeast Atlantic Ocean.MethodsWe reviewed a total of 172 scientific publications assessing connectivity or population structure in 48 species. From this material, we summarised the main patterns of connectivity and population structure across species, as well as the taxonomic and geographic representation of the scientific literature within this field.ResultsOur review shows that contemporary connectivity with adjacent seas is high, but asymmetric, for most species. Simultaneously, most species have multiple distinct populations in the Skagerrak, separate from those in adjacent seas. Within the Skagerrak, population structure is common both among coastal populations and between coastal and offshore populations, but less frequent among offshore populations. In many mobile species, multiple populations temporarily overlap in certain areas, but retain their genetic divergence through homing or other barriers to gene flow.Main ConclusionsEven in one of the most intensively studied marine regions within the field of connectivity and population structure, there are still large knowledge gaps limiting both our understanding of connectivity and its application in management decisions. Nevertheless, it is evident that the presence of population structure despite high connectivity, and temporal variability in population assemblages, poses a challenge for area-based protection measures. This underscores the need for adaptive management that monitors and manages intra-specific diversity on multiple temporal and spatial scales