Portail Hal-l'Institut Agro Rennes-Angers
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How will the cumulative effects of fishing and climate change affect the health and resilience of the Celtic Sea ecosystem?
No full textInternational audienceEcosystems are subject to increasing anthropogenic pressures worldwide. Assessing cumulative effects of multiple pressures and their impacts on recovery processes is a daunting scientific and technical challenge due to systems' complexity. However, this is of paramount importance in the context of ecosystem-based management of natural systems.Our study provides major insights into the assessment of cumulative effects on Northeast Atlantic ecosystems. Using an Ecopath with Ecosim (EwE) tropho-dynamic model for the Celtic Sea ecosystem including 53 functional groups, we (1) assess individual and cumulative effects of fishing and climate change and (2) explore the impact of fishing intensity and climate change on ecosystem resilience. Various levels of increasing fishing intensities are simulated over the whole 21st century, by forcing the EwE model with time series of sea temperature, primary production and secondary producer's biomass from the regional POLCOMS-ERSEM climate model, under both RCP4.5 and RCP8.5 scenarios. Cumulative impacts on the ecosystem's health and its capacity to recover after the cessation of fishing activities were assessed through a set of 45 indicators (biomass-based, diversity, trait-based and habitat-based indicators), using a theoretical non-fishing and climate-constant scenario as a reference.Our results reveal climate change impacts on Boreal, pelagic species and on ecosystem stability. Fishing preferentially removes apex predators and is predicted to increase the likelihood of a regime shift by decreasing ecosystems' capacity to recover. Predicted cumulative effects are mainly additive and antagonistic but synergies are observed for high fishing effort levels, and finally climate change had minor impacts on ecosystem recovery to fishing. Fishing is shown to be the main driver of cumulative impacts and of ecosystem resilience over the next decades. Our results suggest that slight reduction in fishing effort is enough to compensate the impact of climate change. Future research should then be directed towards exploring and evaluating ecosystem-based climate-adaptive fisheries management strategies
Assessing and mapping changes in soil ecosystem services and soil threats in agroecosystems through scenario-based approaches – A systematic review
No full textInternational audienceScenario analysis plays a central role in estimating how global changes affect the relationships linking ecosystem conditions and functioning to human needs. This is particularly true for agroecosystems, which are pivotal to ensure sustainable land planning, ecological management and food security strategies. Soils are key providers of multiple ecosystem services (ES) in agroecosystems but they are very sensitive to global drivers such as changes in climate, land use and cover. How agroecosystems should achieve sustainability, through optimizing soil capacity to supply ES while limiting the occurrence of threats, is a priority of EU policy agendas. Nevertheless, there is currently a lack of a comprehensive framework of scenario-based approaches to assess changes in soil ES (SES) and soil threats (ST). As a part of the project SERENA funded by the European Joint Program on Agricultural Soil Management, this study aims to: i) understand how drivers of global change are commonly studied in the scientific literature; ii) identify how some SES and ST are assessed in scenario-based approaches; iii) provide a preliminary discussion on how soil properties are represented in these approaches. Through a systematic review of 230 published articles related to seven SES and ten ST, this study highlights that not all SES and ST are considered with the same frequency and geographic distribution in scenario-based approaches. Despite a great methodological variability in the assessment and mapping of SES and ST, dominant methodological trends can be identified. SES are mapped more frequently than ST and, specific SES appear more disposed to spatially explicit assessments than others. Due to its novelty and complexity, research on this topic is limited to a small subset of ST or SES and projections of the combined impacts of climate, land use and management changes on multiple ST and SES should be a scientific priority to help policy makers
Bioenergetic adaptations of small intestinal epithelial cells reduce cell differentiation enhancing intestinal permeability in obese mice
No full textInternational audienceObjective: Obesity and overweight are associated with low-grade inflammation induced by adipose tissue expansion and perpetuated by altered intestinal homeostasis, including increased epithelial permeability. Intestinal epithelium functions are supported by intestinal epithelial cells (IEC) mitochondria function. However, diet-induced obesity (DIO) may impair mitochondrial activity of IEC and consequently, intestinal homeostasis. The aim of the project was to determine whether DIO alters the mitochondrial function of IEC, and what are the consequences on intestinal homeostasis.Methods: C57Bl/6J mice were fed a control diet for 22 weeks or a high fat diet (58 kcal% fat). Bioenergetic adaptations of IEC were evaluated on isolated crypts and villi from mouse jejunum. To determine the link between mitochondrial function and alterations of intestinal homeostasis in response to lipid overload, we used the jejunal epithelial cell line IPEC-J2 in vitro and mouse jejunum organoids.Results: Here, we report that DIO in mice induced lipid metabolism adaptations favoring lipid storage in IEC together with reduced number, altered dynamics and diminished oxidative phosphorylation activity of IEC mitochondria. Using the IPEC-J2 cell line, we showed that IEC lipid metabolism and oxidative stress machinery adaptations preceded mitochondrial bioenergetic ones. Moreover, we unraveled the intricate link between IEC energetic status and proliferation / differentiation balance since enhancing mitochondrial function with the AMPK activator AICAR in jejunal organoids reduced proliferation and initiated IEC differentiation and conversely. We confirmed that the reduced IEC mitochondrial function observed in DIO mice was associated with increased proliferation and reduced differentiation, promoting expression of the permissive Cldn2 in the jejunal epithelium of DIO mice.Conclusions: Our study provides new insights into metabolic adaptations of IEC in obesity by revealing that excess lipid intake diminishes mitochondrial number in IEC, reducing IEC differentiation that contribute to increased epithelial permeability
Evaluation of control strategies implemented in a multiphysics generic greenhouse dynamic model
No full textInternational audienceIn Northwestern Europe, soilless cultivation comes with an important and unsustainable energy consumption in heated tomato greenhouses. Agricultural practices need to be improved through reducing their environmental impacts, while producers also have to anticipate the agronomical consequences of the climate change to maintain the farm’s economic viability. Complementary to experiments, multiphysics greenhouse dynamic models simulations can shed light on technical solutions and provide insights towards better practices. Starting from a modular physics-based model of a 1000 m2 experimental greenhouse compartment, this paper focuses on the integration of detailed control strategies for the equipment (thermal and shading screens, roof vents, heating pipes) and for the setpoints (temperature, humidity, CO2 concentration). The objectives require a time-continuous approach: the observation period can indeed be from a few minutes (actuators operation, weather changes) up to the complete production season (11 months) for the crop growth and yield. PID-based control is implemented, and control strategies are integrated in a way aiming at being generic. The approach allows evaluating the effects of different indoor climate settings and equipment control on the utilities consumption (energy, water, CO2) by simulation, should the use case be an existing greenhouse or a prospective one dedicated to the assessment of specific technical solutions.Compared with a reference simulation case, several strategies were evaluated concerning the screens control, the temperature and the CO2 setpoint control, as well as planting period postponing. For instance, applying a systematic offset of -1°C on the indoor temperature setpoint leads to a 19.4 % decrease in energy consumption, with a yield loss of 1.7 %
Comprendre les contrastes de fertilité chimique des sols agricoles français
No full textInternational audienceLa Base de Données des Analyses de Terre (BDAT, Info&Sols – INRAE) rassemble depuis 1990 plus de 3,6 millions de résultats d’analyses physico-chimiques de sols agricoles de surface, réalisés à la demande des agriculteurs par des laboratoires agréés. Les travaux réalisés jusqu’à présent ont principalement mobilisé des analyses univariées (Saby et al., 2017), limitant la compréhension intégrée des relations entre propriétés du sol. Une analyse multivariée couplée à une approche de classification non supervisée a permis de mettre en évidence six groupes de fertilité chimiques, qui mettent en évidence des correspondances avec l’occupation technico-économique des communes françaises (Agreste, 2020) et aux types de sols dominants sur le territoire français (Messant et al., 2021)
Unraveling fouling formation in falling-film evaporators at the micron-scale
No full textInternational audienceUnderstanding fouling formation and preventing its consequences is crucial in the dairy industry to improve the efficiency of unit operations and the quality of the products. To date, most of the literature associated dairy fouling development to the heat-induced denaturation of whey proteins, which represent a major component of the deposits. Most of these studies focused on the fouling dynamics in the case study of heat exchangers, where the operating temperature is higher than whey protein denaturation one. This led to diametrically opposite results based on the off-line analysis of the deposits. Conversely, the fouling mechanisms have been rarely explored in falling-film evaporators, where operating temperatures are lower, despite their systematic use in the processing scheme of dairy powders (e.g., infant milk formula).In a recent work [1], we employed an original rheometry approach to show how the initiation of the fouling of dairy products is not exclusively linked to protein thermal unfolding above the denaturation temperature, but also to the high shear rates near the equipment walls. Encouraged by these results, we performed here a direct observation of the fouling growth in a channel using microfluidic devices replicating the typical environmental and flow conditions of falling-film evaporators. Our results allow us to discriminate the mechanisms governing protein aggregation in the bulk solution and those occurring at the surface and leading to growing deposits
Identification of phytocytokine-encoding genes induced in response to Erwinia amylovora and the chemical elicitor acibenzolar-S-methyl in apple tree
No full textInternational audiencePhytocytokines, a class of small secreted peptides (SSPs) with signaling roles, are essential for various plant physiological processes. However, accurately detecting and annotating them remains challenging due to their varied sequence conservation across species and the limited understanding of their biological functions. In apple, the availability of a high-quality genome enabled the exploration of five phytocytokine gene families, selected on the basis of their deregulated profiles in response to biotic stresses: phytosulfokine (PSK), inflorescence deficient in abscission/-like (IDA/IDL), PAMP-induced secreted peptide (PIP), plant peptide containing sulfated tyrosine (PSY), and C-terminally encoded peptide (CEP). Using a custom bioinformatics protocol that combined genome mining, homology searches, peptide motif detection, and chromosomal organization analysis, we exhaustively identified the secreted peptide precursors and associated genes for those five peptide families in apple. Further transcriptomic analyses revealed their deregulation in response to Erwinia amylovora, the causal agent of fire blight in pomoids, and a chemical elicitor (acibenzolar-S-methyl). Additionally, we investigated orthology relationships with Arabidopsis thaliana homologs. Those results represent the first step towards the identification and characterization of apple tree SSPs involved in biotic stress responses
L'intelligence artificielle, un levier pour accompagner les transitions en élevage ?
No full textNational audienceL'intelligence artificielle, un levier pour accompagner les transitions en élevage ? Depuis plus de 20 ans, des services numériques conçus par la recherche et les entreprises privées ont aidé les agriculteurs dans leurs pratiques d’élevage. Avec l’intelligence artificielle, un pas de plus est franchi. Entre bénéfices, limites et impacts, quelles sont aujourd’hui les applications qui se profilent en élevage
Understanding stratification during evaporation of colloidal dispersions (dairy and model)
No full textPrésentation oraleInternational audienceProducing biomimetic dairy powders with nutritional benefits passes through the challenging control of their physical properties, such as shape and mechanical response of the dry particles. Recent studies highlighted colloid stratification in the skin of drying droplets of dairy protein mixes, which influence their final morphology. However, unraveling the stages of protein stratification remains an unsolved question, limiting the control of the drying process1-6. To fill this gap (Figure 1), in this study we investigate the evaporation of colloid suspensions in Hele-Shaw cells with different height under controlled environmental conditions7-8. The drying dynamics of silica colloids (HS40, TM50) and dairy proteins (whey proteins and casein micelles) were explored by digital microscopy. We characterized the formation and propagation of parallel cracks in the setup to deduce how interfacial colloid self-arrangement influences the mechanical properties of the matrices. Our preliminary findings show good agreement with existing models, though the influence of colloid size remains to be validated. The evaporation rate seemed to decrease throughout the evaporation, as underlined by the cyclical slowdown of crack propagation and the emergence of transversal cracks delimiting regions with increasing width. This specific behavior can be explained by the different internal stress distribution moving inward the cell, closely linked to the predicted variation in terms of evaporation rate.To corroborate our hypothesis and quantify the drying kinetics for single colloids and mixes, the drying-induced mass loss is currently monitored by ultraprecision balance. Coupling microscopy and mass measurements we aim at modeling the drying process at the micron-scale and predict powder properties
Adaptive Strategies of the invasive aquatic plant, Ludwigia grandiflora subps.hexapetala : Contrasting Plasticity Between Aquatic and Terrestrial Morphotypes
No full textBiological invasion is the fifth biggest threat to biodiversity and ecosystem processes. Invasive species are able to colonise new environments rapidly due to their phenotypic plasticity. Ludwigia grandiflora subsp. hexapetala (Lgh), an aquatic invasive plant, invades various aquatic habitats, such as rivers, ponds, and more recently, especially in France, wet meadows. More recently, a terrestrial morphotype, emergent for half the year, has been identified. The behaviour of aquatic and terrestrial morphotypes in aquatic and terrestrial conditions was analysed through observations of morphological traits, and assays of metabolomics and phytohormones 14 and 28 days after the beginning of the experiment. The phenotypic plasticity was evaluated by calculating the relative distance plasticity index (RDPI) in response to environmental changes (terrestrial versus aquatic). RDPI were measured for morphological preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission