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Disentangling the relative impacts of climate change and human activities on fluvial sediment supply to the coast by the world's large rivers: Pearl river basin, china
No full textThe world's large rivers are under stress and experiencing unprecedented changes in hydrology, ecosystems, and fluvial sediment loads. Many of these rivers terminate at the great deltas of the world (home to 500 million people), which depend on fluvial sediments for their very existence. While fluvial sediment loads of large rivers have already been greatly modified by human activities, climate change is expected to further exacerbate the situation. But how does the effect of climate change on fluvial sediment loads compare with that of human impacts? Here, we address this question by combining historical observations and 21st century projections for one of the world's largest 25 rivers containing two mega dams; Pearl River, China. Our analysis shows that variations in fluvial sediment supply to the coast from the Pearl river over a similar to 150 year study period are dominated by human activities. Projected climate change driven 21st century increases in riverflow will only compensate for about 1% of the human induced deficit in sediment load, leading to the coastal zone being starved of about 6000 Mt of sediment over the remainder of this century. A similar dominance of human impacts on fluvial sediment supply is likely at other heavily engineered rivers
Relations entre modes de gestion des agroécosystèmes et biodiversité fonctionnelle des sols
No full textNotre contexte économique, environnemental et sociétal actuel nous incite à considérer, dans le cadre
de la transition agroécologique, des pratiques agricoles limitant l’usage d’intrants de synthèse et
favorisant la biodiversité planifiée dans les agroécosystèmes. Ces pratiques mobilisent certains services
écosystémiques réalisés par la biocénose du sol. Dans cette communication, nous présentons les
principales composantes de la biocénose du sol et certains services écosystémiques associés. Nous
abordons ensuite les impacts des principales pratiques culturales (labour, fertilisation) et des modes de
gestion des terres alternatifs. Nous concluons sur l’importance de la préservation de la biodiversité des
sols sur la fertilité des agroécosystèmes, et suggérons des pratiques clés d’amélioration telles que
l’augmentation de la diversité végétale dans les systèmes de culture.The current economic, environmental and social context encourages a transition to agroecological
practices that limit the use of synthetic inputs and enhance planned biodiversity in agroecosystems.
Such practices mobilize a number of ecosystem services provided by soil organisms. This
communication presents the principal components of the soil biota and associated ecosystem services.
The impacts of the main soil management practices (tillage, fertilization) and of alternative systems are
then described. In conclusion we stress the importance of soil biodiversity conservation for
agroecosystem fertility and functioning, and suggest a few key improvements such as increasing plant
diversity in agricultural systems
Premiers résultats du réseau Biovigilance 500 ENI sur le suivi des effets non-intentionnels des pratiques agricoles sur la biodiversité.
No full textPour évaluer les effets non intentionnels des pratiques agricoles sur la biodiversité, un réseau de 500
parcelles (réseau Biovigilance 500 ENI) a été mis en place en France métropolitaine par les pouvoirs
publics. Quatre taxons sont suivis depuis 2012 : les vers de terre, la flore des bordures de champs, les
coléoptères et les oiseaux. Nous présentons ici des résultats préliminaires et descriptifs pour la faune et
une analyse plus détaillée de la réponse de la flore aux variables environnementales et agricoles. Des
approches multivariées et des modèles additifs généralisés mixtes ont été utilisés pour tester les liens
entre la nature et la diversité des traits de 186 espèces végétales et 12 variables environnementales et
agricoles. Outre un effet de la diversité du paysage, de la fréquence de gestion et de la largeur des
bordures, la quantité d’engrais azotés apportés dans la parcelle a un effet sur la composition de la flore
des bordures en favorisant les espèces les plus nitrophiles. La richesse en espèces et leur diversité
fonctionnelle diminuent avec l’indice de fréquence de traitements (IFT) herbicides et avec la surface de
la parcelle. Les premiers résultats obtenus sont cohérents et montrent la valeur des données récoltées
par les observateurs du réseau Biovigilance 500 ENI pour identifier les effets non-intentionnels des
pratiques sur la biodiversité.To assess the unintended effects of agricultural practices on biodiversity, a network of 500 plots
(Biovigilance 500 ENI network) was set up in metropolitan France by the public authorities. Four taxa
have been monitored since 2012: earthworms, flora of field margins, beetles and birds. Here we present[br/]
preliminary and descriptive results for wildlife and a more detailed analysis of the response of flora to
environmental and agricultural variables. Multivariate approaches and generalized additive mixed
models were used to test the links between the nature and diversity of 186 plant species traits and 12
environmental and agricultural variables. In addition to an effect of landscape diversity, field margin
management frequency and field margin width, the amount of nitrogen fertilizer applied within the field
has an effect on the composition of the flora of field margin favoring the most nitrophilous species.
Species richness and functional diversity decrease with the Treatment Frequency Index (IFT) of
herbicides and with the field area. The first results obtained are consistent and show the value of the
data collected by observers of the Biovigilance 500 ENI network to identify unintended effects of farming
practices on biodiversity
Spatiotemporal large-scale networks shaped by air mass movements
No full textThe movement of atmospheric air masses can be seen as a continuous and generally complex flow of gases and particles hovering over our planet. It can however be locally simplified by considering three-dimensional trajectories of air masses connecting distant areas of the globe during a given period of time.
In this paper, we present a mathematical framework to construct spatial and spatiotemporal networks where the nodes are the subsets of a partition of a geographical area and the links between these nodes are inferred from sampled trajectories of air masses passing over and across the nodes. We propose different estimators of link intensities relying on different bio-physical hypotheses and covering adjustable time periods. This approach leads to a new class of spatiotemporal networks characterized by adjacency matrices giving, e.g., the probability of connection between distant areas during a chosen period of time.
To illustrate the effectiveness of this approach, we applied it to characterize tropospheric connectivity in two real geographical contexts: the watersheds of the French region Provence-Alpes-Côte d'Azur and the coastline of the Mediterranean Sea. The analysis of the constructed networks allowed identifying a marked seasonal pattern in air mass movements in the two study areas.
The networks constructed from air mass trajectories can be used to investigate issues, e.g., in aerobiology and epidemiology of airborne plant pathogens. Similar networks could be estimated from other types of trajectories, such as animal trajectories, to characterize connectivity between different components of the landscape where the animals live
Environmental and molecular drivers of the alpha-gal syndrome
No full textThe alpha-Gal syndrome (AGS) is a type of allergy characterized by an IgE antibody (Ab) response against the carbohydrate Gal alpha 1-3Gal beta 1-4GlcNAc-R (alpha-Gal), which is present in glycoproteins from tick saliva and tissues of non-catarrhine mammals. Recurrent tick bites induce high levels of anti-alpha-Gal IgE Abs that mediate delayed hypersensitivity to consumed red meat products in humans. This was the first evidence that tick glycoproteins play a major role in allergy development with the potential to cause fatal delayed anaphylaxis to alpha-Gal-containing foods and drugs and immediate anaphylaxis to tick bites. Initially, it was thought that the origin of tick-derived alpha-Gal was either residual blood meal mammalian glycoproteins containing alpha-Gal or tick gut bacteria producing this glycan. However, recently tick galactosyltransferases were shown to be involved in alpha-Gal synthesis with a role in tick and tick-borne pathogen life cycles. The tick-borne pathogen Anaplasma phagocytophilum increases the level of tick alpha-Gal, which potentially increases the risk of developing AGS after a bite by a pathogen-infected tick. Two mechanisms might explain the production of anti-alpha-Gal IgE Abs after tick bites. The first mechanism proposes that the alpha-Gal antigen on tick salivary proteins is presented to antigen-presenting cells and B-lymphocytes in the context of Th2 cell-mediated immunity induced by tick saliva. The second mechanism is based on the possibility that tick salivary prostaglandin E2 triggers Immunoglobulin class switching to anti-alpha-Gal IgE-producing B cells from preexisting mature B cells clones producing anti-alpha-Gal IgM and/or IgG. Importantly, blood group antigens influence the capacity of the immune system to produce anti-alpha-Gal Abs which in turn impacts individual susceptibility to AGS. The presence of blood type B reduces the capacity of the immune system to produce anti-alpha-Gal Abs, presumably due to tolerance to alpha-Gal, which is very similar in structure to blood group B antigen. Therefore, individuals with blood group B and reduced levels of anti-alpha-Gal Abs have lower risk to develop AGS. Specific immunity to tick alpha-Gal is linked to host immunity to tick bites. Basophil activation and release of histamine have been implicated in IgE-mediated acquired protective immunity to tick infestations and chronic itch. Basophil reactivity was also found to be higher in patients with AGS when compared to asymptomatic alpha-Gal sensitized individuals. In addition, host resistance to tick infestation is associated with resistance to tick-borne pathogen infection. Anti-alpha-Gal IgM and IgG Abs protect humans against vector-borne pathogens and blood group B individuals seem to be more susceptible to vector-borne diseases. The link between blood groups and anti-alpha-Gal immunity which in turn affects resistance to vector-borne pathogens and susceptibility to AGS, suggests a trade-off between susceptibility to AGS and protection to some infectious diseases. The understanding of the environmental and molecular drivers of the immune mechanisms involved in AGS is essential to developing tools for the diagnosis, control, and prevention of this growing health problem
Hormonal Therapy Resistance and Breast Cancer: Involvement of Adipocytes and Leptin
No full textObesity, a recognized risk factor for breast cancer in postmenopausal women, is associated with higher mortality rates regardless of menopausal status, which could in part be explained by therapeutic escape. Indeed, adipose microenvironment has been described to influence the efficiency of chemo- and hormonal therapies. Residual cancer stem cells could also have a key role in this process. To understand the mechanisms involved in the reduced efficacy of hormonal therapy on breast cancer cells in the presence of adipose secretome, human adipose stem cells (hMAD cell line) differentiated into mature adipocytes were co-cultured with mammary breast cancer cells and treated with hormonal therapies (tamoxifen, fulvestrant). Proliferation and apoptosis were measured (fluorescence test, impedancemetry, cytometry) and the gene expression profile was evaluated. Cancer stem cells were isolated from mammospheres made from MCF-7. The impact of chemo- and hormonal therapies and leptin was evaluated in this population. hMAD-differentiated mature adipocytes and their secretions were able to increase mammary cancer cell proliferation and to suppress the antiproliferative effect of tamoxifen, confirming previous data and validating our model. Apoptosis and cell cycle did not seem to be involved in this process. The evaluation of gene expression profiles suggested that STAT3 could be a possible target. On the contrary, leptin did not seem to be involved. The study of isolated cancer stem cells revealed that their proliferation was stimulated in the presence of anticancer therapies (tamoxifen, fulvestrant, doxorubicine) and leptin. Our study confirmed the role of adipocytes and their secretome, but above all, the role of communication between adipose and cancer cells in interfering with the efficiency of hormonal therapy. Among the pathophysiological mechanisms involved, leptin does not seem to interfere with the estrogenic pathway but seems to promote the proliferation of cancer stem cells
Targeting the delivery of dietary plant bioactives to those who would benefit most: from science to practical applications
No full textBACKGROUND: A healthy diet and optimal lifestyle choices are amongst the most important actions for the prevention of cardiometabolic diseases. Despite this, it appears difficult to convince consumers to select more nutritious foods. Furthermore, the development and production of healthier foods do not always lead to economic profits for the agro-food sector. Most dietary recommendations for the general population represent a "one-size-fits-all approach" which does not necessarily ensure that everyone has adequate exposure to health-promoting constituents of foods. Indeed, we now know that individuals show a high variability in responses when exposed to specific nutrients, foods, or diets. PURPOSE: This review aims to highlight our current understanding of inter-individual variability in response to dietary bioactives, based on the integration of findings of the COST Action POSITIVe. We also evaluate opportunities for translation of scientific knowledge on inter-individual variability in response to dietary bioactives, once it becomes available, into practical applications for stakeholders, such as the agro-food industry. The potential impact from such applications will form an important impetus for the food industry to develop and market new high quality and healthy foods for specific groups of consumers in the future. This may contribute to a decrease in the burden of diet-related chronic diseases
Model-based QTL detection is sensitive to slight modifications in model formulation
No full textClassical crop models have been developed to predict crop yield and quality, and they are based on physiological and environmental inputs. After molecular discoveries, models should integrate genetic variation to allow predictions that are more genotype-dependent. An interesting approach, Quantitative Trait Locus (QTL)-based ecophysiological modeling, has shown promising results for the design of ideotypes that are adapted to biotic and abiotic stresses, but there are still limitations to attaining a fully integrated model. The aim of this case study is to clarify the impact of choosing different model equations (closely related and with different numbers of parameters) and optimization methods on the detection of QTLs controlling the parameters of crop growth. Different growth equations were parameterized based on a genetic population by following different approaches. The correlations between parameters were analyzed, and two different strategies were adopted to address the correlation issue. QTL analysis was performed on the optimized values of the parameters of the growth equations and on the observed dry mass (DM) data to validate the QTLs detected. Overall, models and strategies resulted in different QTLs being detected. Similar LOD profiles but with peaks of different heights were observed, some of which were significant, resulting in different numbers of QTLs. In some cases, peaks had slightly different positions or were absent. Even closely related growth models led to the detection of different QTLs. The goodness of fit and complexity of the growth models were found to be insufficient to select the best model. Calculating parameters independently of observed data may not be a good strategy, whereas setting parameters independent of the genotype is recommended. Given the large-scale global optimization problem and the strong correlations between parameters, the two algorithms tested showed poor performance. Currently, the lack of effective algorithms is the main obstacle to answering the question posed. The authors therefore suggest testing different model formulations and comparing the QTLs detected before choosing the best formulation to use in an ecophysiological modeling approach based on QTLs
Dynamic and functional profiling of xylan-degrading enzymes in aspergillus secretomes using activity-based probes
No full textPlant polysaccharides represent a virtually unlimited feedstock for the generation of biofuels and other commodities. However, the extraordinary recalcitrance of plant polysaccharides toward breakdown necessitates a continued search for enzymes that degrade these materials efficiently under defined conditions. Activity-based protein profiling provides a route for the functional discovery of such enzymes in complex mixtures and under industrially relevant conditions. Here, we show the detection and identification of β-xylosidases and endo-β-1,4-xylanases in the secretomes of Aspergillus niger, by the use of chemical probes inspired by the β-glucosidase inhibitor cyclophellitol. Furthermore, we demonstrate the use of these activity-based probes (ABPs) to assess enzyme–substrate specificities, thermal stabilities, and other biotechnologically relevant parameters. Our experiments highlight the utility of ABPs as promising tools for the discovery of relevant enzymes useful for biomass breakdown