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Lysine potentiates insulin secretion via AASS-dependent catabolism and regulation of GABA content and signaling
No full textLysine is an essential amino acid with insulinotropic effects in humans. In vitro, it enhances glucose-stimulated insulin secretion (GSIS) in beta-cell lines and rodent islets. While lysine is thought to act via membrane depolarization similar to arginine, the role of its intracellular metabolism in beta-cell function remains unexplored. Here, we show that lysine acutely potentiates GSIS and that genes encoding enzymes in the lysine degradation pathway, including AminoAdipate-Semialdehyde Synthase (AASS), a key mitochondrial enzyme catalysing the first two steps of lysine catabolism, were present in human pancreatic islets and INS1 832/13 beta cells. Some of these genes including AASS, ALDH7A1, DHTKD1, and HADH, were downregulated in pancreatic islets from type 2 diabetes (T2D) versus non-diabetic (ND) donors. Silencing AASS in human islets and INS1 832/13 beta cells led to reduced GSIS. Integrated transcriptomics and metabolomics revealed altered expression of GABA metabolism genes, reduced GABA content and accumulation of glutamate in Aass-KD cells. Mitochondrial TCA cycle and OXPHOS function was impaired, evidenced by decreased ATP/ADP ratio, diminished glucose-stimulated mitochondrial respiration, and elevated lactate/pyruvate ratio. Cytosolic calcium responses to glucose and GABA were also disrupted. Pharmacological analyses demonstrated that inhibition of GABA synthesis or degradation did not account for the reduced GSIS, but providing substrates and activation of GDH partially restored insulin secretion, pointing to a diminished glutamate supply as a contributing factor. Remarkably, exogenous GABA restored insulin secretion in beta cells and human islets with suppressed AASS-dependent lysine catabolism, supporting a role for GABA as both a metabolic substrate and signaling effector. Together, these findings identify AASS-mediated lysine catabolism as a critical regulator of beta-cell metabolic integrity, linking impaired lysine metabolism to GABA depletion, mitochondrial dysfunction, and secretory failure in T2D islets. They also underscore the nutritional importance of essential amino acids such as lysine in sustaining GSIS and glucose homeostasis, and support therapeutic strategies aimed at restoring lysine catabolism or GABA/glutamate balance to maintain beta-cell function
Greater increase in surface albedo following clear-cutting than wildfire in pine dominated northern Swedish boreal forests
No full textThere is a public debate on how boreal forests can deliver climate change mitigation benefits. While most debates regarding Fennoscandian forests have centered on the contrasting effects of actively managed and old-growth unmanaged forests on carbon uptake and storage, the impact of surface albedo has often been overlooked. According to the new EU forest strategy for 2030, with aim of improving quantity and quality of forests by promoting primary old-growth forests and avoiding clear-cutting, among others, we examined how albedo across a wide age range of boreal Pinus-dominated forests develops over time after wildfire (defined as unmanaged) and clear-cutting (defined as managed). We find that albedo decreases over time after disturbance, but mainly in managed forests. Annual mean albedo in young (<30 years) managed forests (0.36 +/- 0.04) is markedly larger than in young unmanaged forests (0.18 +/- 0.04). This difference is particularly prominent during winter, when snow-covered ground is present. The mean albedo over the entire unmanaged forest-age gradient (0.17 +/- 0.05) is significantly lower (p < 0.05) than that of the managed forest-age gradient (0.23 +/- 0.10). Considering the typically higher frequency of clear-cuts compared to wildfires in Fennoscandian forests, these albedo differences would be even larger over long time scales. Our findings reveal the importance of considering the climatic cooling potential of albedo when making decisions on how to optimize future forest management in northern boreal forests to mitigate climate change
Understanding forest wind damage during mountain wave events: Insights from a case study in Norway
No full textForest wind damage models are typically based on the assumption that windstorm damage results from the interaction between horizontal wind forces and forest stand properties. In complex terrain, mountain waves caused by stably stratified air flowing over mountains can generate standing waves and severe downslope windstorms on the leeward side. Using the windstorm of 19 November 2021 in a mountain valley in southeastern Norway as a case study, we tested two hypotheses: 1. Forest stand properties do not significantly contribute to explaining forest damage during a mountain wave event. 2. Meteorological variables related to atmospheric stratification, turbulence, and non-horizontal airflow significantly contribute to explaining forest damage during a mountain wave event. To test these hypotheses, we combined forest damage observations with a high-resolution numerical weather prediction model and Random Forest modeling. We used SHapley Additive exPlanations (SHAP) values to quantify the contributions of individual model features. Incorporating forest stand variables did not significantly improve predictive performance, whereas potential temperature gradient, vertical airflow velocity, and wind gust speed, capturing turbulence, did. SHAP analysis showed that although wind gust speed helped explain damage, its influence was secondary to that of potential temperature gradient, which had the strongest explanatory power. The model demonstrated good discriminative power between damage and no damage in the test set. Our findings underscore the limitations of conventional models reliant on horizontal wind speed, highlighting the need for high-resolution numerical weather prediction models that resolve three-dimensional flow in complex terrain, especially during mountain wave events
Assessing farmers' willingness to sell straw for energy and material applications in Sweden
No full textThis study examines farmers' willingness to sell straw for energy and material applications in Scania, Sweden. Using interviews and surveys, we tested three empirical consequences derived from the premise that missing data on farmers' willingness to sell straw for energy may misrepresent the biomass supply in potential assessments. Findings reveal willingness to sell straw depends on end use, with farmers preferring benefits like manure in barter arrangements over bioenergy. Land tenure is key; those leasing over 50 % of their land are more likely to be willing to sell. Contrary to expectations, straw supply is not highly price-sensitive; competing uses like animal bedding influence decisions. Up to 57 % (95 % CI: 42-75) of cereal and oilseed land could be made available for energy, though agronomic and competing use limit this potential. These results challenge viewing straw as a residue and highlight the need for region-specific policies reflecting land tenure, local practices, and agronomic priorities. Integrating nutrient recycling, diversified straw uses, and agroecosystem planning could enhance biomass availability and agricultural sustainability. Further research should assess effectiveness, including carbon farming regulations. This study offers insights for aligning bioenergy goals with agricultural sustainability in biomass policy
Nickel: Geochemistry, biochemistry and its role in chemical and biological evolutions
No full textNickel is a versatile element that plays critical roles in Earth's geological and biological evolution, from the depths of the magmatic mantle to the complexity of prebiotic chemistry. While it is not considered the sole catalyst for the origin of life, recent research suggests that Ni may have had a more profound role than traditionally recognized. This review synthesizes Ni isotope geochemistry, biology, and prebiotic chemistry, exploring how Ni isotope variations offer new insights into magmatic processes, hydrothermal systems, and the cycling of Ni through Earth's lithosphere and hydrosphere. We summarize the pathways of Ni in oceanic environments, highlighting its influence on biogeochemical cycles and microbial metabolisms that shape global ecosystems. Furthermore, we examine the essential roles of Ni in biological systems, focusing on its function as a catalytic metal in enzymes crucial for nitrogen and carbon cycling. Extending to the prebiotic world, we evaluate Ni's potential in catalyzing life's earliest chemical reactions, including the polymerization of amino acids and the fixation of CO2, possibly driven by unique metal-ligand interactions. Our comprehensive review positions Ni as a pivotal element across geological timescales and environments, underscoring its relevance to both planetary and biochemical processes
A novel framework to study the evolution of crop rotation diversity reveals changes towards regional crop type specialisation in Sweden
No full textDiversification of cropping systems can help decrease the negative environmental impacts of agriculture while increasing ecosystem service benefits to crop production. The crop diversification measure introduced by the 2013 CAP reform aimed to trigger the diversification of cropping systems. There is currently no framework to show how policies that aim to trigger diversification of cropping systems, affect crop rotation diversity at the field scale. In this study, we propose a framework to study the evolution of cropping system diversity, which comprises (1) building crop sequences for two periods using the Geo-spatial Application (GSA) database of the Integrated Administration and Control System (IACS), (2) calculating two indicators of diversity of crop sequences, (3) creating a typology of crop sequences, and (4) determining the significance of change and highlighting drivers of change by using mixed models. Our framework was tested on 1100,760 ha in Sweden, focusing on the periods 2005-2010 and 2011-2016, with four ways of categorizing crops (i.e., crop species, crop types, winter crops vs spring crops, botanical family) in five homogeneous production regions. Using different crop categorization is a way of expressing the robustness of the trends in diversity which account for various relationships among crops. We showed that the value of all diversity indicators in all regions decreased significantly between the two periods, except for the estimated agronomic quality of the crop sequence in the most productive regions where it increased. This general decrease could be explained by longer duration of rotational perennial leys and reduced cultivation of minor cereals, such as rye and oats in the later period. Overall, there was an 8 % increase in ley area, which was particularly evident in regions with less productive land, where the high proportion of ley often became permanent grassland. We found that the trend towards longer duration leys was strong in livestock farms, while regions with productive land favoured the inclusion of more annual cash crops in the rotation, especially oilseed rape, which contributed to the agronomic quality of the sequences. The framework could be widely adopted across Europe using the GSA database of the IACS to track diversification changes at a country and regional level and design appropriate policies to increase the diversity of crop rotations using the potential local drivers highlighted
Impact of organic amendments on carbon stability and carbon use efficiency in acidic and alkaline soils
No full textSoils represent the largest reservoir of organic carbon in terrestrial ecosystems, yet the mechanisms controlling its stabilization and turnover are still not fully understood, limiting our ability to anticipate their response to climate change. Microbial processes are central to the formation, preservation, and loss of soil organic carbon (SOC), with microbial carbon use efficiency (CUE)—the fraction of assimilated carbon allocated to growth versus respiration—emerging as a key integrative parameter of microbial functioning. While CUE has been proposed as a predictor of SOC persistence, its contribution remains debated. In parallel, CUE is gaining attention in the context of carbon farming policies, as it links microbial functioning with soil carbon sequestration. Among the management practices aimed at enhancing SOC, organic amendments such as compost and biochar stand out for their capacity to influence CUE and improve soil functioning. In this study, we assessed how different organic amendments affect SOC stability and sequestration in two contrasting soils from the Iberian Peninsula: acidic grasslands and alkaline rain-fed soils. The amendments included four biochars, two cattle digestates, a green compost, and a biochar–compost mixture. Over 100 days, soil respiration (CO₂ emissions), microbial biomass, and soil properties were monitored using an automatic respirometer. Microbial CUE and microbial activity largely determined carbon (C) retention in the studied soils. Cow digestate increased microbial activity but reduced microbial CUE in both soils, leading to higher C losses through respiration and lower C retention. In contrast, biochars—particularly those produced from white poplar wood, olive pomace and rice husk—enhanced carbon recalcitrance, extending the residence time of the stable C pool by six to nine times compared with unamended soils. Microbial analyses showed that bacterial loads were 2–3 orders of magnitude higher than fungal loads. Compared with acidic grassland soils, alkaline soils generally showed higher microbial CUE values, reflecting a greater potential for C sequestration. These findings also indicate that microbial CUE exhibited clear soil-specific behavior, being consistently higher in the AS than in the acidic GS. This pattern suggests that differences in microbial community dominance—particularly the relative contribution of bacteria and fungi—may underlie the contrasting CUE responses observed between soils, a topic that warrants further investigation in future studies. In the alkaline soils, digestate amendments resulted in the highest bacterial abundance, whereas rice husk biochar favored fungal growth. Additionally, the high Cu and Zn content of cow manure digestate posed risks in acidic soils. This study also emphasizes that amendment strategies should be tailored to soil type to optimize carbon sequestration. Moreover, a novel thermal–respirometry correlation model was also developed, providing a practical tool for assessing soil carbon dynamics and C stability
Understanding food waste generation in school canteens
No full textReducing food waste across food supply chains is crucial for achieving global environmental goals, but the impact of organisational strategy and social factors on food waste in public catering is not well understood. This study aimed to quantify and explain the drivers of food waste in Swedish school canteens by analysing data at three levels: the organisational, the school, and the individual level. The analysis combined national survey data (n = 111 municipalities), schoollevel quantification data (n = 693 schools), and 1722 individual on-site observations. The results show that municipalities with a higher share of guests eating in production kitchens had lower food waste (Spearman’s ρ = − 0.23) while having an explicit food waste reduction goal did not affect food waste levels (45 vs 47 g per guest). At the school level, student age was moderately correlated with plate waste (Kendall’s τ = 0.34), with older students wasting about twice as much food as younger ones (36 vs 18 g per guest). At the individual level, extroverted students and those in group settings generated more waste (on average 67 g per waster).The findings point to complementary roles of organisational factors and guest behaviour in shaping food waste generation, highlighting the potential of interventions that address both
Biogeochemical response to drying-rewetting in riparian soils influences carbon mobilization
No full textOrganic-rich riparian soils in northern boreal landscapes are often the primary source of organic and inorganic carbon (C) to headwater streams. During extreme hydro-climatic events, such as droughts, the production and mobilization of C in these soils may be sensitive to changes in groundwater levels. Yet, the biogeochemical effects of drying and rewetting have been under-investigated in boreal riparian zones, particularly when compared to peat soils in discrete landscape components (i.e., mires). Here, we experimentally assess the response of riparian soil cores to simulated drought and rewetting and test whether mobilization of dissolved organic matter (DOM), carbon dioxide (CO2), and methane (CH4) are altered by geochemical and biological drivers over a two-month rewetting period. Drought oxidized the soil profile, upregulated activities of oxidative enzymes, and replenished terminal electron acceptors (TEAs), most notably sulfate (SO4 2− ), which likely suppressed DOM concentrations over the short term. However, over the longer term, soil DOM mobilization increased in response to rewetting, unrelated to the intensity of experimental drought. Enzyme activity during the rewetting phase indicates that the persistent increases in DOM may be linked to microbially-mediated decomposition of organic matter following drought. By contrast, CO2 production was sensitive to drought intensity, with concentrations suppressed in soils subjected to the most extreme drying treatment. Elevated SO4 2− concentrations also delayed the recovery of CH4 production in soils by creating a pool of more favorable TEAs. Our results collectively show that mobilization of different C forms in riparian soils is influenced by drying-rewetting events through multiple biogeochemical mechanisms operating at different time scales. These findings have broader implications for the lateral transfer of organic and inorganic C from riparian zones to streams in response to predicted increases in climate variability
Landscape-scale drivers of insect pest regulation in sugar beet
No full textRecent policy shifts sparked by environmental and health concerns, insecticide resistance development, and limited new registrations have caused a dwindling availability of chemical insecticides. Sugar beet, a major cash crop in temperate agricultural systems, relied on now banned neonicotinoid insecticide seed coatings for pest control, creating a need for sustainable alternatives. Using a monitoring dataset from 134 sugar beet fields in Denmark and Sweden collected over five years, we assessed landscape-scale drivers of the occurrence and damage of five dominant sugar beet pests in the region: black bean aphid, flea beetles, beet leafminers, pygmy mangold beetle and thrips. We found that insect pests generally cause limited damage to sugar beet in our study area, with damage thresholds for any of the five pests being exceeded in 20 % of the fields. Damage by thrips was more common in Denmark and damage by flea beetles and beet leafminer eggs were more common in Sweden. Pest occurrence or damage could only partly be explained by landscape-scale factors. Cropland cover was positively related to black bean aphid and thrips damage presence but negatively related to flea beetle and pygmy mangold beetle damage. Edge density was negatively related to black bean aphid occurrence but positively related to flea beetle damage. An inter-annual increase in host crop cover was positively related to flea beetle damage and crop diversity to beet leafminer infestation. We conclude that further research on the cause and countermeasures for insect pest outbreaks is needed to develop economically and environmentally sustainable insect pest regulation in sugar beet