Gardarin A.,French National Institute for Agricultural Research |
Guillemin J.-P.,AgroSup Dijon |
Munier-Jolain N.M.,French National Institute for Agricultural Research |
Colbach N.,French National Institute for Agricultural Research
European Journal of Agronomy | Year: 2010
In fields, the timing of weed emergence flushes is mostly related to the timing and rate of seed germination, which depend on soil temperature and water potential as well as soil tillage and crop sowing date. Base temperature and base water potential for seed germination are parameters required in weed dynamics models to take into account the effects of soil conditions on weed demography. Since these parameters are difficult to measure, our objective was to develop a method for estimating them from easily accessible information. Data on base temperature and base water potential for germination were collected from the literature for 28 weed species. Correlations were then searched for between these parameters and (i) the species ecological indicator values of Landolt and Ellenberg for temperature and moisture and (ii) dates of the onset and end of weed emergence based on experts' knowledge. Both base temperature and base water potential for germination were partially correlated with the species indicator values found in the literature. These correlations explained however only a small proportion of the variance of base temperature and water potential. In contrast, the base temperature of spring-emerging species was highly correlated with the mean soil temperature at the mean onset date of each species' spring emergence flush. Water potential for germination was higher for species requiring high base temperature. The date of spring emergence onset of a species, which can be easily assessed from experts' knowledge, can thus be used to estimate their base temperature and then their base water potential for germination. © 2009 Elsevier B.V. All rights reserved.
Guillemin J.-P.,AgroSup Dijon |
Chauvel B.,French National Institute for Agricultural Research
Weed Biology and Management | Year: 2011
Common ragweed (Ambrosia artemisiifolia L.) is one of the annual plants that were described recently as invasive weeds in Europe. This species is described as an invasive plant that produces seeds that are highly variable. Its production of variably sized seeds is regarded as promoting its spread in different environments. Experiments were carried out to determine the influence of the seed weight and temperature on germination and the influence of the seed weight and burial depth on seedling emergence. The seeds were divided into a number of classes of weight and the seed weight effect on germination was evaluated by Petri dish assays. In another experiment, the seeds were buried at different depths in a clay soil/sand mix to estimate the burial effect on germination and seedling emergence. The germination level of A. artemisiifolia was high overall, between 76.8% and 94.2%. The seed germination was modified by temperature but it was not influenced by the seed weight. The amounts of germination and seedling emergence were greater for the seeds on the soil surface and decreased with an increasing burial depth, from 2 to 8cm. No germination or emergence was observed for the seeds that were buried at 10 and 12cm. The lightest seeds were more sensitive to burial. A greater level of seedling emergence for those seeds that were placed near the soil surface could explain the success of this species in open habitats, where the probability of deeper burial is low. After high seed production, the management of A. artemisiifolia in fields could be partly achieved through soil tillage, burying seeds below 10cm, and not carrying out deep soil tillage the following year. © 2011 AgroSup Dijon. Weed Biology and Management © 2011 Weed Science Society of Japan.
Cerf M.,French National Institute for Agricultural Research |
Guillot M.N.,French National Institute for Agricultural Research |
Olry P.,AgroSup Dijon
Journal of Agricultural Education and Extension | Year: 2011
How do change agents deal with the diversity of farmers' attitudes towards the future of agriculture? How do they themselves cope with change and understand their role as change agents? We chose a comprehensive, action-training approach to answer such questions and worked with agents belonging to two different extension networks. The agents acknowledged their historically built professional models and discussed their professional situations in relation to the need to develop new skills and to address new audiences. Some dimensions of these situations were pointed out as crucial in the change process: (1) the agent's position among farmers and those who act to change farming practices at local level; (2) the tension between the agent's engagement in promoting more environmentally-friendly practices, and the role that managers and farmers assign to the agent; and (3) the way of combining scientific and technical knowledge with farmers' own knowledge. Our work also highlighted the diversity of the agents' points of view on change at farm level (discontinuity versus continuity) and the way to handle it: respectively by making the discontinuity visible and manageable at farm level, or by supporting a step-by-step management of change at cropping-system level. The added value has been to develop a method which enables advisers to learn together from their professional situations, and thus to show the need to investigate how the agent's subjectivity is a key driver of a change intervention. © 2011 Wageningen University.
Blancard S.,AgroSup Dijon |
Martin E.,AgroSup Dijon
Energy Policy | Year: 2014
Measuring energy efficiency is crucial when planning energy reduction policies. However, decision makers are understandably reluctant to act in the absence of solid data and results supporting a policy position. This paper proposes a methodology to measure the energy efficiency of farms based on the Data Envelopment Analysis (DEA) approach. In a manner similar to the cost framework, we decompose energy efficiency measurements into technical and allocative efficiencies in energy contents of inputs. In this study, we replace input prices used in traditional economic efficiency measurements by their energy content. We use the energy efficiency model to explore the optimal input-mix that produces the current outputs at minimum energy-consumption. We demonstrate that this decomposition can help policy makers design accurate energy policies. However, the uncertainty of the data and, more particularly, the energy content of the inputs leads us to recommend using the methodologies to calculate the bounds of efficiency to obtain more plausible and robust results. Based on our analysis, energy efficiency is not a fixed value, and policy-makers should consider it with caution. We use a 2007 database of French farms specialised in field crops for empirical illustration. © 2013 Elsevier Ltd.
Severin I.,AGROSUP DIJON |
Dumont C.,AGROSUP DIJON |
Jondeau-Cabaton A.,AGROSUP DIJON |
Graillot V.,AGROSUP DIJON |
Chagnon M.-C.,AGROSUP DIJON
Toxicology Letters | Year: 2010
5-Hydroxymethylfurfural (5-HMF) is known as an indicator of quality deterioration in a wide range of foods. 5-HMF is formed as an intermediate in the Maillard reaction and has been identified in a wide variety of heat-processed foods. In recent years, the presence of 5-HMF in foods has raised toxicological concerns: data have shown cytotoxic, genotoxic and tumoral effects but further studies suggest that 5-HMF does not pose a serious health risk. However the subject is still a matter of debate. We investigated the genotoxicity of the food-borne contaminant 5-HMF using the Ames test, the micronucleus (MN) and the single-cell gel electrophoresis (SCGE) assays in the human metabolically active HepG2 cell line. Cytotoxic effect of 5-HMF was first assessed using Alamar Blue™ as a sensitive sub-lethal assay. 5-HMF did not induce any genic mutation in bacteria whatever the concentration in the Ames test. Furthermore, it does not induce clastogenic or aneugenic effects in the HepG2 cells. In contrast, 5-HMF induced HepG2 DNA damage at concentrations from 7.87 to 25 mM in the comet assay suggesting a weak genotoxic effect of 5-HMF in the HepG2 cells probably repaired. © 2009 Elsevier Ireland Ltd. All rights reserved.
McDonnell C.K.,Teagasc |
McDonnell C.K.,University College Dublin |
Allen P.,Teagasc |
Morin C.,AgroSup Dijon |
Lyng J.G.,University College Dublin
Food Chemistry | Year: 2014
The aim of this study was to assess the effect of power ultrasound (US) treatment (4.2, 11 or 19 W cm-2 for 10, 25 or 40 min) on water-protein interactions during the salting of pork. All US treatments increased the protein extraction above that of the control (p < 0.001), with the exception of 4.2 W cm-2 for 10 and 25 min. Differential scanning calorimetry indicated myosin denaturation at the surface of the sample treated with the highest power (19 W cm-2, 40 min). There was no effect on water binding capacity assessed by centrifuge, however, low-field nuclear magnetic resonance T21 relaxation was increased by 19 W cm -2 (p < 0.05). No changes to the meat matrix were evident by light microscopy. Findings indicate that US salting could be a surface phenomenon which can accelerate mass transfer and extract protein but denature myosin at high power inputs. Potential could exist for US to enhance conventional curing techniques. © 2013 Published by Elsevier Ltd.
Mession J.-L.,Agrosup Dijon |
Sok N.,Agrosup Dijon |
Assifaoui A.,Agrosup Dijon |
Assifaoui A.,University of Burgundy |
Saurel R.,Agrosup Dijon
Journal of Agricultural and Food Chemistry | Year: 2013
The heat-induced denaturation and aggregation of mixed pea globulins (8%, w/w) were investigated using differential scanning calorimetry (DSC), SDS-PAGE, and size-exclusion chromatography (SEC-HPLC). DSC data showed that the pea proteins denaturation temperature (Td) was heating-rate dependent. The Td value decreased by about 4 C by lowering the heating rate from 10 to 5 C/min. The SDS-PAGE analysis revealed that protein denaturation upon heating at 90 C was mainly governed by noncovalent interaction. The SEC-HPLC measurements indicated that low-denatured legumin (≈350-410 kDa) and vicilin/convicilin (≈170 kDa) globulins were heat-denatured and most of their subunits reassociated into high-molecular weight, soluble aggregates (>700 kDa). The addition of N-ethylmaleimide slightly modified the aggregation route of pea globulins. However, partially insoluble macroaggregates were produced in the presence of dithiothreitol, reflecting the stabilizing effect of disulfide bonds within legumin subunits. © 2013 American Chemical Society.
Fisk I.D.,University of Nottingham |
Boyer M.,Agrosup Dijon |
Linforth R.S.T.,University of Nottingham
European Food Research and Technology | Year: 2012
The release of volatile compounds, such as aroma, from a food material during hydration is of wide relevance to the food industry. To this end, dry powders of varying chemical composition were hydrated in a controlled system to investigate the impact of varying composition (protein, lipid and carbohydrate) on the delivery rate of volatile compounds to the headspace. Additional lipid and carbohydrate reduced the concentration of volatile compounds in the headspace and accelerated their rate of delivery to the headspace. Protein had no measurable impact. Of the volatile compounds measured, 2,3 butanedione and acetaldehyde were shown to be released slowly into the headspace, and pyrrol, methyl acetate and pyridine were released rapidly; this differential release rate was strongly correlated with hydrophobicity and would indicate that during hydration there is a temporal dimension to the relative abundance of volatile compounds in the headspace. © 2012 The Author(s).
Mession J.-L.,AgroSup Dijon |
Assifaoui A.,AgroSup Dijon |
Assifaoui A.,University of Burgundy |
Cayot P.,AgroSup Dijon |
Saurel R.,AgroSup Dijon
Food Hydrocolloids | Year: 2012
Soluble and natural mixed pea proteins (PP) were extracted from defatted pea seeds according to acidic precipitation (PPP) or ultrafiltration/diafiltration (PPDF) procedures. The isolates contained proteins with a low level of denaturation. Mixed pea globulins isolates presented quite similar solubility and thermal profiles, also a similar polypeptide composition. Vicilin/convicilin 7S (Vic) and legumin 11S (Leg) fractions were obtained by batch chromatography using a salt gradient for the elution. Several incompatible systems were built by mixing the pea proteins with an anionic polysaccharide (sodium alginate, SA), when biopolymers were both negatively charged. Most of mixtures exhibited a phase separation phenomenon. From phase diagrams, experimental binodal curves obtained with either mixed globulins or legumin fraction were apparently very close. However phase boundary was better-defined with the Leg fraction. No macroscopic phase separation was evidenced for mixtures with the vicilin fraction. Microstructure of the PP-SA mixtures was investigated by confocal microscopy (CLSM) according to PP composition and biopolymer initial composition. The Leg-SA and most of PPP-SA mixtures exhibited a droplet-like structure, while structure of PPDF-SA mixtures was aggregated-like. With mixed PP, an alginate entrapment within the PP-enriched phase would disturb phase separation. Also density and shape of the protein-enriched microdomains influenced kinetics of demixing. Polydispersity within the PP-SA mixtures, in terms of wide range molecular weights distribution and charge heterogeneity would explain such differences. © 2012 Elsevier Ltd.
News Article | November 24, 2016
Drosophila epithelium. An enterocyte (green) dumps its damaged contents into the intestinal lumen. Also visible are actin filaments (red) and DNA (blue). Credit: © Catherine Socha. Though purging is not prescribed as often as it was centuries ago, intestinal cells known as enterocytes frequently resort to this age-old remedy. Researchers from the Immune Response and Development in Insects (CNRS), Molecular Immunorheumatology (INSERM / Université de Strasbourg), and PAM Food Science and Microbiological Processes (AgroSup Dijon / Université de Bourgogne) laboratories have demonstrated that enterocytes attacked by pathogenic bacteria rapidly purge themselves of most of their contents. This protects them from infection and leads to a drastic though temporary thinning of the intestinal lining, or epithelium. This work, published on November 23 in Cell Host & Microbe, may eventually shed light on inflammatory bowel diseases like Crohn's disease. Serratia marcescens is an opportunistic bacterium common throughout our environment. Drosophila flies fed a steady diet of S. marcescens die in days. However, analysis of the intestinal epithelium every 24 hours reveals no apparent damage. The researchers decided to study what happens during the first few hours after infection. They found that, during this initial period, the epithelium is remarkably thinner, and seems almost to have disappeared. But it recovers its original thickness in the hours that follow. Enterocytes lose much of their cytoplasm, having expelled most of their contents, though not their nuclei. These cells thereby rid themselves of damaged organelles, of some of the bacteria attempting to penetrate the intestinal wall, and bacterial toxins. This process leaves the epithelium temporarily thinner. The presence of hemolysin, a bacterial toxin that forms pores in the membranes of its target cells, triggers cell purging. The researchers showed that a mutant strain of S. marcescens unable to secrete hemolysin is for this reason actually more virulent. Though the toxin is no longer at its disposal, its absence means the enterocytes are not triggered to initiate protective purging, and the bacteria can then damage the epithelium with other virulence factors. Further studies have shown that this thinning and regrowth of the intestinal epithelium is characteristic of bees, mice, and humans alike. More research will be necessary to determine the molecular mechanisms involved and, more broadly, whether anomalies in this process can help elucidate the causes of inflammatory bowel diseases like Crohn's disease. More information: Enterocyte purge and rapid recovery is a resilience reaction of the gut epithelium to pore-forming toxin attack. Lee KZ, Lestradet M, Socha C, Schirmeier S, Schmitz A, Spenlé C, Lefebvre O, Keime C, Yamba WM, Bou Aoun R, Liegeois S, Shwab Y, Simon-Assmann, P, Dalle F, Ferrandon D. Cell Host Microbe. 23 Nov 2016.