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Functionalized chitosan as an alternative to polyacrylamide flocculents for phase separation of sewage sludge digestate
No full textInternational audienceSolid and liquid phase separation of sewage sludge digestate may be improved by addition of coagulation-flocculation reagents. Currently there is a rising interest for natural biopolymers made from renewable resources such as chitosan. If chitosan use is limited to acidic conditions allowing its solubility, its functionalization, by grafting for example a cationic charge (quaternary ammonium), may extend its application. In this study, chitosans, with different origin and molar weight, are functionalized at different quaternization degrees (glycidyltrimethylammonium chloride use) and tested as flocculents of two sewage sludge digestates. The effects of functionalized-chitosan addition on physico-chemical properties of digestates, as well as on their filterability and settleability, is assessed for different quaternization degrees, origins, molar weights and doses, and compared with the ones obtained with two usual commercial flocculents. The particle size distribution and rheological behavior of the digestate are focused as main physico-chemical parameters. Functionalized-chitosan addition results (i) in a monomodal distribution, different from the one obtained with commercial flocculents and (ii) in a decrease of the digestate viscosity, contrary to the commercial flocculents addition. Regarding solid and liquid phase separation, functionalized-chitosan addition results in an efficient phase separation close to the ones obtained with usual commercial flocculents. Separation efficiency is mainly correlated with the dose rather than with the quaternization degree, and an optimum is reached for a given molar weight and origin
Assessment of Salt Stress Effects on Antioxidant Levels and Membrane Transport Protein in Amaranthus caudatus
No full textInternational audienceSalt stress is a major environmental challenge for plants, leading to various physiological and biochemical responses. This study investigates the impact of salt stress on lipid peroxidation, phenolic and flavonoid accumulation, free-radical scavenging antioxidant activity, glutathione content, tocopherol levels in three amaranth (Amaranthus caudatus L) genotypes: Red Cascade (Red), Green Cascade (Green), and Pony Tail Mixed (Pony). The results showed that, under salt stress, lipid peroxidation increased, causing cell membrane damage and compromising cell integrity. However, salt stress also triggered the accumulation of phenolic and flavonoid compounds, which possess strong antioxidant properties and play a crucial role in scavenging reactive oxygen species. The total antioxidant activity as measured by DPPH inhibition was significantly enhanced in all genotypes under salt stress, with the Green genotype showing the highest activity. Additionally, salt stress induced an increase in total glutathione levels, maintaining the GSH/GSSG ratio relatively constant in all genotypes. However, tocopherol content decreased significantly under salt stress, with the Green genotype being the most affected. Finally, as membrane compounds are affected by oxidative stress, an analysis of membrane trafficking in root epidermal cells revealed that the Pony genotype had the highest response of the three genotypes. Overall, these findings suggest that salt stress induces complex responses in A. caudatus genotypes, involving oxidative damage, phenolic and flavonoid accumulation, enhanced antioxidant activity, and alterations in tocopherols and enhanced membrane trafficking. Understanding these responses can contribute to the development of salt-tolerant crops and improve agricultural productivity under saline conditions
Accounting for functionality in the identification of global conservation priorities: promises and pitfalls
No full textInternational audienceWhereas preventing species extinctions remains a central objective of conservation efforts, it must be complemented by the long-term preservation of functional ecosystems and of the benefits humans derive from them. Here, I review recent approaches that explicitly account for functionality in setting large-scale conservation priorities, discussing their promise while highlighting challenges and pitfalls. Crossing data on species’ distributions and ecological traits has enabled the mapping of global patterns of functional diversity and functional rarity and the identification of species that stand out for their functional distinctiveness. However, the priorities identified through these general indices do not directly address ecosystem functionality, instead, they are methods for ensuring the representation of individual functional traits as intrinsically valuable biodiversity elements. Three other approaches integrate functionality into large-scale priorities by taking into account the specific context of each ecosystem, site or species: the International Union for Conservation of Nature's Red List of Ecosystems, Key Biodiversity Areas and the Green Status of Species. Currently at various stages of development, testing and implementation, these approaches are playing an increasingly important role in the definition, implementation and monitoring of global- and national-scale conservation strategies to ensure the long-term persistence of ecosystem functions and associated ecosystem services. This article is part of the discussion meeting issue ‘Bending the curve towards nature recovery: building on Georgina Mace's legacy for a biodiverse future’
Potassium extrusion by plant cells: evolution from an emergency valve to a driver of long‐distance transport
No full textInternational audienceThe ability to accumulate nutrients is a hallmark for living creatures and plants evolved highly effective nutrient transport systems, especially for the uptake of potassium (K + ). However, plants also developed mechanisms that enable the rapid extrusion of K + in combination with anions. The combined release of K + and anions is probably an ancient extrusion system, as it is found in the Characeae that are closely related to land plants. We postulate that the ion extrusion mechanisms have developed as an emergency valve, which enabled plant cells to rapidly reduce their turgor, and prevent them from bursting. Later in evolution, seed plants adapted this system for various responses, such as the closure of stomata, long‐distance stress waves, dropping of leaves by pulvini, and loading of xylem vessels. We discuss the molecular nature of the transport proteins that are involved in ion extrusion‐based functions of plants and describe the functions that they obtained during evolution
Grapevine cell response to carbon deficiency requires transcriptome and methylome reprogramming
No full textInternational audienceSugar limitation has dramatic consequences on plant cells, which include cell metabolism and transcriptional reprogramming, and the recycling of cellular components to maintain fundamental cell functions. There is however no description of the contribution of epigenetic regulations to the adaptation of plant cells to limited carbon availability. We investigated this question using non-photosynthetic grapevine cells (Vitis vinifera, cv Cabernet Sauvignon) cultured in vitro with contrasted glucose concentrations. Sugar depletion in the culture medium led to a rapid cell growth arrest and a major metabolic shift that include the depletion in soluble sugar and total amino acids and modulation of the cell redox status. Consistently, flux modeling showed a dramatic slowdown of many pathways required for biomass accumulation such as cell wall and protein synthesis. Sugar depletion also resulted in a major transcriptional reprogramming, characterized by the induction of genes involved in photosynthesis, and the repression of those related to sucrose mobilization or cell cycle control. Similarly, the epigenetic landscape was deeply modified. Glucose-depleted cells showed a higher global DNA methylation level than those grown with glucose. Changes in DNA methylation mainly occurred at transposable elements, and at genes including some of those differentially expressed, consistent with an important role for methylation to the adaptation of cells to limited sugar availability. In addition, genes encoding histone modifiers were differentially expressed suggesting that additional epigenetic mechanisms may be at work in plant cells under carbon shortage
Life History Trait Evolution in the Context of Host– Parasite Interactions
No full textInternational audienceThis chapter explores how the presence of parasites can affect the evolution of host life- history traits (reproduction, longevity and dispersal), and conversely, how host demography or life history selects for changes in parasite life history (latency, within-host growth, transmission/dispersal). We discuss how shifts in host life history can mitigate the negative effects of parasites and look for evidence of parasite-mediated changes in life history in different systems. Parasite life history parallels that of free-living organisms, but with the added problem of virulence. How virulence relates to other parasite life history traits is quintessential for parasite fitness. This is because transmission requires exploitation of host resources, which reduces host health. At the same time, parasite life history (and by definition virulence) evolution are at the mercy of host demography. We present different results highlighting parasite life history (and virulence) evolution in response to different host mortality regimes, timing and/or mode of transmission. We further discuss how dispersal, as both a host and parasite life history trait, affects reciprocal evolution of both players and how it covaries with other traits (e.g., virulence). To illustrate the importance of the biotic environment, we provide an overview of how co-infection, when a host is infected with more than 1 parasite, can affect both host and parasite life history evolution. One main general message is that theoretical predictions depend on correlations between different life history traits and between life history and interaction traits (e.g., resistance, infectivity, etc.). Thus the genetic trait architecture in host and parasite might be a key determinant of epidemiological feedbacks and (co)evolutionary outcomes. This highlights the importance of studying host- parasite life history across scales, from the individual to the metapopulation to the community level
Regional Model to Predict Sugarcane Yield Using Sentinel-2 Imagery in São Paulo State, Brazil
No full textInternational audienceSugarcane yield prediction is an important tool to support the sugar-energy sector. This study aimed to create a regional empirical model, using the random forest algorithm, to predict sugarcane yield in the state of Sao Paulo. For this, we used Sentinel-2 imagery (vegetation indices NDVIRE and CIRE, spectral bands Red-edge and near-infrared arrow), agronomic data (variety and ratoon stage and plant cane), climatic data (temperature, precipitation) and crop water deficit data from three mills. We created two predictive yield model based on three scenarios with different training and testing data: (SI) Scenario I is the regional model considered all data from the three mills, (SII) Scenario II was training similar SI and testing individuals for each mill, (SIII) Scenario III includes regional individual’s models for sugarcane ratoon stage and plant cane. In each case, 70% of the dataset was used for training and 30% for testing. SI gave R2 equal to 0.72, while SII R2 was between 0.60 and 0.78; the RMSE for SI was 11.7 , while for SII from 8.62 to 15.56 . The rRMSE was 16.5% for SI and from 12.4 to 21.6%, for SII. SIII showed R2 greater than 0.61, and RMSE between 9.6 and 13.5 . The CIRE and NDVIRE vegetation indices, crop water deficit and precipitation were the most important variables to estimate sugarcane yield. The model created considering SI and SII showed potential to be applied to different locals using data from three mills
Prevalence of food insecurity during pregnancy in Latin American and the Caribbean countries: a systematic review
No full textInternational audienceIn Latin American and Caribbean countries (LAC), women are particularly affected by food insecurity (FI). This gender gap can be amplified at certain key periods in life, particularly during pregnancy, with negative consequences for maternal and infant health. In the current geopolitical and health context, it is essential to take stock of the prevalence of FI among pregnant women in this region, and the associated economic and psychosocial determinants. From 168 publications identified on Pubmed and Scopus, this systematic review selected 13 publications in 7 LAC countries. Although the published data only described the situation before the COVID-19 pandemic (2009-2019), the prevalence of FI in this population was already worrying, ranging from 28.2% to 64.9%. Only 4 out of 13 studies investigated socio-economic and psychosocial determinants among mothers in this region. Thus, the factors most frequently reported concerned mothers' demographic characteristics (advanced age, ethnic minority), household socio-economic characteristics (low income, poorest wealth quartile, precarious housing, welfare recipients), the absence of a stable partner and a low education level. High prevalences of FI have also been associated with mental distress during pregnancy. In conclusion, few recent studies (notably none since the COVID-19 pandemic) have been published in this region on the issue of FI among women during pregnancy. Yet this knowledge is essential to the development of a logical framework for the implementation and evaluation of public health programs aimed at women and children. By reducing the FI of mothers in the LAC region, we will contribute to reducing the social inequalities in health that often manifest themselves very early in life
Agricultural practices in olive groves modify weeds floral traits and resources throughout the year
No full textInternational audienceHighlights: • Community level weeds floral traits are linked to flower productivity in olive groves. • Both weeds morphological and phenological traits are linked to flower productivity. • Weeds floral traits and flower productivity are modified by agricultural practices. • Low-regime mowing filters weeds communities producing more diverse floral resources that are available during a longer period. • Irrigation, fertilization and pedoclimate also impact weeds floral resources.Abstract: Lack of floral resources is suspected to be one of the factors involved in flower-visiting insect declines. Because agricultural landscapes are often poor in flowers, it seems crucial to assess weeds as floral resources to feed flower-visiting insects and to identify the factors that drive floral productivity, defined as floral biomass produced by the weed community. We monitored floral presence, productivity and traits in 16 olive groves from September 2021 to June 2022. The objectives were to understand to which extinct abiotic factors, among agricultural practices, pedoclimate and weather, determine floral productivity and to analyse the relationships between floral traits, floral presence and productivity. We found mowing frequency (2–3 per year on average) increased mean floral area and height, advanced flowering onset, and increased floral functional diversity and flowering species richness, which in turn increased floral presence and productivity
Linking ecotoxicological effects on biodiversity and ecosystem functions to impairment of ecosystem services is a challenge: an illustration with the case of plant protection products
No full textInternational audienceThere is growing interest in using the ecosystem services framework for environmental risk assessments of chemicals, including plant protection products (PPPs). Although this topic is increasingly discussed in the recent scientific literature, there is still a substantial gap between most ecotoxicological studies and a solid evaluation of potential ecotoxicological consequences on ecosystem services. This was recently highlighted by a collective scientific assessment (CSA) performed by 46 scientific experts who analyzed the international science on the impacts of PPPs on biodiversity, ecosystem functions, and ecosystem services. Here, we first point out the main obstacles to better linking knowledge on the ecotoxicological effects of PPPs on biodiversity and ecological processes with ecosystem functions and services. Then, we go on to propose and discuss possible pathways for related improvements. We describe the main processes governing the relationships between biodiversity, ecological processes, and ecosystem functions in response to effects of PPP, and we define categories of ecosystem functions that could be directly linked with the ecological processes used as functional endpoints in investigations on the ecotoxicology of PPPs. We then explore perceptions on the possible links between these categories of ecosystem functions and ecosystem services among a sub-panel of the scientific experts from various fields of environmental science. We find that these direct and indirect linkages still need clarification. This paper, which reflects the difficulties faced by the multidisciplinary group of researchers involved in the CSA, suggests that the current gap between most ecotoxicological studies and a solid potential evaluation of ecotoxicological consequences on ecosystem services could be partially addressed if concepts and definitions related to ecological processes, ecosystem functions, and ecosystem services were more widely accepted and shared within the ecotoxicology community. Narrowing this gap would help harmonize and extend the science that informs decision-making and policy-making, and ultimately help to better address the trade-off between social benefits and environmental losses caused by the use of PPPs