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Available and missing data to model impact of climate change on European forests
No full textClimate change is expected to cause major changes in forest ecosystems during the 21st century and beyond. To assess forest impacts from climate change, the existing empirical information must be structured, harmonised and assimilated into a form suitable to develop and test state-of-the-art forest and ecosystem models. The combination of empirical data collected at large spatial and long temporal scales with suitable modelling approaches is key to understand forest dynamics under climate change. To facilitate data and model integration, we identified major climate change impacts observed on European forest functioning and summarised the data available for monitoring and predicting such impacts. Our analysis of c. 120 forest-related databases (including information from remote sensing, vegetation inventories, dendroecology, palaeoecology, eddy-flux sites, common garden experiments and genetic techniques) and 50 databases of environmental drivers highlights a substantial degree of data availability and accessibility. However, some critical variables relevant to predicting European forest responses to climate change are only available at relatively short time frames (up to 10-20 years), including intra-specific trait variability, defoliation patterns, tree mortality and recruitment. Moreover, we identified data gaps or lack of data integration particularly in variables related to local adaptation and phenotypic plasticity, dispersal capabilities and physiological responses. Overall, we conclude that forest data availability across Europe is improving, but further efforts are needed to integrate, harmonise and interpret this data (i.e. making data useable for non-experts). Continuation of existing monitoring and networks schemes together with the establishments of new networks to address data gaps is crucial to rigorously predict climate change impacts on European forests
The Demonstration of an Aqp4/Tgf-Beta 1 Pathway in Murine Astrocytes Holds Implications for Both Neuromyelitis Optica and Progressive Multiple Sclerosis
No full textThe role exerted by Aquaporin 4 (AQP4) as a regulator of astrocyte immune functions has been poorly explored. A recent report demonstrates that under neuroinflammatory conditions, the expression of Aqp4 on murine astrocytes is mandatory for the effective control of acute inflammation in the central nervous system. Such an immunomodulatory function appears to be mediated by a promotion of the transforming growth factor beta 1 (Tgfb1) pathway. Here, these results are discussed in the context of neuromyelitis optica (NMO) and multiple sclerosis (MS) progressive forms. It is proposed that NMO and progressive MS might rely on opposite molecular mechanisms involving, in NMO, an acutely-defective AQP4/TGFB1 pathway and, in progressive MS, a chronically-stimulated AQP4/TGFB1 pathway. Data supporting the involvement of angiotensin II as a molecular link between AQP4 and TGFB1 are also reviewed
Impact of a resistance gene against a fungal pathogen on the plant host residue microbiome: the case of the Leptosphaeria maculans-Brassica napus pathosystem
No full textOilseed rape residues are a crucial determinant of stem canker epidemiology, as they support the sexual reproduction of the fungal pathogen Leptosphaeria maculans. The aim of this study was to characterise the impact of a resistance gene against L. maculans infection on residue microbial communities and to identify micro-organisms interacting with this pathogen during residue degradation. We used near-isogenic lines to obtain healthy and infected host plants. The microbiome associated with the two types of plant residues was characterised by metabarcoding. A combination of linear discriminant analysis and ecological network analysis was used to compare the microbial communities and to identify micro-organisms interacting with L. maculans. Fungal community structure differed between the two lines at harvest, but not subsequently, suggesting that the presence/absence of the resistance gene influences the microbiome at the base of the stem whilst the plant is alive, but that this does not necessarily lead to differential colonisation of the residues by fungi. Direct interactions with other members of the community involved many fungal and bacterial ASVs (amplicon sequence variants). L. maculans appeared to play a minor role in networks, whereas one ASV affiliated to Plenodomus biglobosus (synonym Leptosphaeria biglobosa) from the Leptosphaeria species complex was considered a keystone taxon in the networks at harvest. This approach could be used to identify and promote micro-organisms with beneficial effects against residue-borne pathogens, and more broadly, to decipher the complex interactions between multi-species pathosystems and other microbial components in crop residues
Intracellular osmoprotectant concentrations determine Propionibacterium freudenreichii survival during drying
No full textPropionibacterium freudenreichii is a beneficial bacterium widely used in food as a probiotic and as a cheese-ripening starter. In these different applications, it is produced, dried, and stored before being used. Both freeze-drying and spray-drying were considered for this purpose. Freeze-drying is a discontinuous process that is energy-consuming but that allows high cell survival.Spray-drying is a continuous process that is more energy-efficient but that can lead to massive bacterial death related to heat, osmotic, and oxidative stresses. We have shown that P. freudenreichii cultivated in hyperconcentrated rich media can be spraydried with limited bacterial death. However, the general stress tolerance conferred by this hyperosmotic constraint remained a
black box. In this study, we modulated P. freudenreichii growth conditions and monitored both osmoprotectant accumulation and stress tolerance acquisition. Changing the ratio between the carbohydrates provided and non-protein nitrogen during growth under osmotic constraint modulated osmoprotectant accumulation. This, in turn, was correlated with P. freudenreichii tolerance towards different stresses, on the one hand, and towards freeze-drying and spray-drying, on the other. Surprisingly, trehalose accumulation correlated with spray-drying survival and glycine betaine accumulation with freeze-drying. This first report showing the ability to modulate the trehalose/GB ratio in osmoprotectants accumulated by a probiotic bacterium opens new perspectives for the optimization of probiotics production
Assessment of Soil Erosion by Quantile Estimates for European Regions : Displaying Quantile Estimates of Fertilizer Cost for European Regions
No full textThe decision to adopt one or another of the sustainable land management alternatives should not be based
solely on their respective benefits in terms of climate change mitigation but also based on the performances
of the productive systems used by farm holdings, assessing their environmental impacts through the cost of
specific resources used. This communication uses the symbolic data analysis tools in order to analyse the
conditional quantile estimates of the fertilizer costs of specific productions in agriculture, as a replacement
proxy for internal soil erosion costs. After recalling the conceptual framework of the estimation of agricultural
production costs, we present the empirical data model, the quantile regression approach and the interval data
techniques used as symbolic data analysis tools, mainly symbolic principal component analysis and symbolic
clustering of the estimation intervals. The comparative analysis of econometric results for main products
between European regions illustrates the relevance of the displays obtained for inter-regional comparisons
based on specific productivity.La décision d'adopter l'une ou l'autre des alternatives de gestion durable des terres ne doit pas être basée uniquement sur leurs avantages respectifs en termes d'atténuation du changement climatique mais également sur les performances des systèmes de production utilisés par les exploitations agricoles, en évaluant leurs impacts environnementaux à travers le coût des ressources spécifiques utilisées. Cette communication utilise les outils de l'analyse de données symboliques afin d'analyser les estimations quantiles conditionnelles des coûts de production spécifique agricole en engrais, comme substitut pour les coûts d'érosion interne des sols. Après avoir rappelé le cadre conceptuel de l'estimation des coûts de production agricole, nous présentons le modèle de données empiriques, l'approche de régression quantile et les techniques de données d'intervalle utilisées comme outils d'analyse des données symboliques, principalement l'analyse des composantes principales symboliques et la classification symbolique des intervalles d'estimation. L'analyse comparative des résultats économétriques des principaux produits entre les régions européennes illustre la pertinence des affichages obtenus pour les comparaisons interrégionales basées sur une productivité spécifique
Model uncertainty, nonlinearities and out-of-sample comparison: evidence from international technology diffusion
No full textThis paper reconsiders the international technology diffusion model. Because the high degree of uncertainty surrounding the Data Generating Process and the likely presence of nonlinearities and latent common factors, it considers alternative nonparametric panel specifications which extend the Common Correlated Effects approach and then contrasts the out-of-sample performance of them with those of more common parametric models. To do so, we adopt an approach recently proposed within the literature of nonparametric regression. This approach is based on a pseudo Monte Carlo experiment that takes its roots on cross validation and aims at testing whether two competing approximate models are equivalent in terms of their expected true error. Our results indicate that the adoption
of a nonparametric approach provides better performances. This work also refines previous results by showing threshold effects, nonlinearities and interactions, which are obscured in parametric specifications and which have relevant implications for policy
Harvesting of Prebiotic Fructooligosaccharides by Nonbeneficial Human Gut Bacteria
No full textPrebiotic oligosaccharides, such as fructooligosaccharides, are increasingly being used to modulate the composition and activity of the gut microbiota. However, carbohydrate utilization analyses and metagenomic studies recently revealed the ability of deleterious and uncultured human gut bacterial species to metabolize these functional foods. Moreover, because of the difficulties of functionally profiling transmembrane proteins, only a few prebiotic transporters have been biochemically characterized to date, while carbohydrate binding and transport are the first and thus crucial steps in their metabolization. Here, we describe the molecular mechanism of a phosphotransferase system, highlighted as a dietary and pathology biomarker in the human gut microbiome. This transporter is encoded by a metagenomic locus that is highly conserved in several human gut Firmicutes, including Dorea species. We developed a generic strategy to deeply analyze, in vitro and in cellulo, the specificity and functionality of recombinant transporters in Escherichia coli, combining carbohydrate utilization locus and host genome engineering and quantification of the binding, transport, and growth rates with analysis of phosphorylated carbohydrates by mass spectrometry. We demonstrated that the Dorea fructooligosaccharide transporter is specific for kestose, whether for binding, transport, or phosphorylation. This constitutes the biochemical proof of effective phosphorylation of glycosides with a degree of polymerization of more than 2, extending the known functional diversity of phosphotransferase systems. Based on these new findings, we revisited the classification of these carbohydrate transporters. [br/]
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IMPORTANCE Prebiotics are increasingly used as food supplements, especially in infant formulas, to modify the functioning and composition of the microbiota. However, little is currently known about the mechanisms of prebiotic recognition and transport by gut bacteria, while these steps are crucial in their metabolism. In this study, we established a new strategy to profile the specificity of oligosaccharide transporters, combining microbiomics, genetic locus and strain engineering, and state-of-the art metabolomics. We revisited the transporter classification database and proposed a new way to classify these membrane proteins based on their structural and mechanistic similarities. Based on these developments, we identified and characterized, at the molecular level, a fructooligosaccharide transporting phosphotransferase system, which constitutes a biomarker of diet and gut pathology. The deciphering of this prebiotic metabolization mechanism by a nonbeneficial bacterium highlights the controversial use of prebiotics, especially in the context of chronic gut diseases
The IL-15 / sIL-15Rα complex modulates immunity without effect on asthma features in mouse
No full textBackground
Interleukin 15 (IL-15) is a growth and modulating factor for B, T lymphocytes and natural killer cells (NK). Its action on innate and adaptive immunity is modulated by its alpha chain receptor (IL-15Rα). The IL-15/sIL-15Rα complex (IL-15Cx) increases the bioavailability and activity of the cytokine in vivo. IL-15Cx has been used in diseases to dampen IL-15 inflammation by the use of soluble IL-15Ralpha specificity. Here, we aim to evaluate the interest of IL-15Cx in a mouse model of asthma.
Methods
Using a mouse model of asthma consisting in percutaneous sensitization and intranasal challenge with total house dust mite extract, we evaluated the effect of IL-15Cx injected intraperitoneally four times after a first nasal challenge. Respiratory function was assessed by the technique of forced oscillations (Flexivent®). The effect on bronchial remodeling was evaluated by lung histology. The inflammatory status was analyzed by flow cytometry.
Results
We observed that the IL-15Cx modulates lung and systemic inflammation by increasing NK cells, CD8+ memory T cells and regulatory cells. However, IL-15Cx displays no effect on bronchial hyperreactivity, bronchial remodeling nor cellular bronchial infiltrate, but limits the secretion of bronchial mucus and modulates only inflammatory response in a HDM-allergic asthma murine model.
Conclusions
IL-15Cx has a limited effect on immune response in asthma and has no effect on lung function in mice. Thus, it limits its therapeutic potential but might suggest a combinatory potential with other therapeutics