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Trace elements in soils and vegetables from market gardens of (peri)urban areas in Marrakech city. 9. International Congress on Soils of Urban, Industrial, Traffic, Mining and Military Areas (SUITMA)

Microbial concentrations, enzymatic activities and trace element contents in urban soils of Marrakech city according to an anthropogenic gradient. 9. International Congress on Soils of Urban, Industrial, Traffic, Mining and Military Areas (SUITMA)

Les oligo-éléments : du « feed » au « food » et de l’ajustement des apports chez les volailles à la valorisation des produits en alimentation humaine. . 12.Journées de la recherche avicole et palmipèdes à foie gras

A trace elements-based approach to tropical dendrochronology. 7. Journées Scientifiques et Techniques du Réseau des Microscopistes de l'INRA (RμI)

International audience; The ripening of industrial soft cheeses manufactured using a liquid pre-cheese produced from the ultrafiltration (UF) of milk was observed to be slow in comparison to that of cheese manufactured by a traditional process. Moreover, in the UF-cheeses investigated in this study, which were produced using Penicillium camemberti as the surface flora, several surface defects were observed: the texture was 'carton' like and the rind frequently detached from the cheese. To gain a fuller understanding of the development of these surface defects in UF-cheeses, the migration of different minerals and ions, and the study of the rind microstructure by scanning electron microscopy and X-ray mapping were performed. The results suggest that the slower diffusion of lactate, possibly due to the mineral layer at the surface of cheeses, acting as a barrier to its diffusion, may have caused an alteration in the metabolism and growth of the surface mould and may explain the surface defects of these UF-cheeses.; Les fromages à pâte molle industriels produits par ultrafiltration (UF) à partir d'un pré-fromage liquide présentent un affinage retardé par rapport à des fromages produits à l'aide d'un procédé traditionnel. De plus, des fromages UF modèles produits avec seulement Penicillium camemberti comme flore de surface montrent une texture de carton et la croûte se détache souvent du fromage. La caractérisation des migrations des minéraux et des ions et l'étude de la microstructure de la croûte de ces fromages modèles par microscopie électronique à balayage et micro-analyse X ont été réalisées afin de comprendre l'origine de ces défauts. La diffusion retardée du lactate, peut-être due à la présence d'une couche minérale à la surface des fromages, pourrait être à l'origine de changements de métabolisme et de la croissance de la moisissure et pourrait expliquer la moindre qualité des fromages.

International audience; Assessment of recharge, paleo-recharge and groundwater residence time of aquifer systems of the Sahel is pivotal for a sustainable management of this vulnerable resource. Due to its stratified aquifer system, the Lake Chad Basin (LCB) offers the opportunity to assess recharge processes over time and to link climate and hydrology in the Sahel. Located in north-central Africa at the fringe between the Sahel and the Sahara, the lake Chad basin (LCB) is an endorheic basin of 2,5.106 km2. With a monsoon climate, the majority of the rainfall occurs in the southern one third of the basin, the Chari/Logone River system transporting about 90% of the runoff generated within the drainage basin. A complex multi-layer aquifer system is located in the central part of the LCB. The Quaternary unconfined aquifer, covering 500 000 km2, is characterized by the occurrence of poorly understood piezometric depressions. Artesian groundwaters are found in the Plio-Pleistocene lacustrine and deltaic sedimentary aquifers (early Pliocene and Continental Terminal). The present-day lake is in hydraulic contact with the Quaternary Aquifer, but during past megalake phases, most of the Quaternary aquifer was submerged and may experience major recharge events. To identify active recharge area and assess groundwater dynamics, one hundred surface and groundwater samples of all layers have been collected over the southern part of the LCB. Major and trace elements have been analyzed. Measurements of 36Cl have been carried out at CEREGE, on the French 5 MV AMS National Facility ASTER and 14C activities have been analyzed for 17 samples on the French AMS ARTEMIS. Additionally, the stable isotopic composition was measured on the artesian aquifer samples. In the Quaternary aquifer, results show a large scatter with waters having very different isotopic and geochemical signature. In its southern part and in the vicinity of the surface waters, groundwaters are predominantly Ca-Mg-HCO3 type waters with very high 36Cl/Cl ratio (>1000.10-15 at/at) very likely linked to the bomb pulse. These high 36Cl/Cl ratios are in the same order than the 36Cl/Cl signature of surface waters active modern recharge in this area. In the other part of the Quaternary Aquifer, waters are Na-HCO3-SO4-Cl type and are characterized by lower 36Cl/Cl ratios (around 200.10-15 at/at), suggesting longer residence time of the groundwaters. The 14C contents of the unconfined aquifer waters are all above 50 pmc, suggesting recent or Holocene recharge of this system. In contrast, the confined aquifer has a more homogeneous geochemical signature. The 14C contents are below all 0.5 pmc and mainly below detection level. 36Cl/Cl ratios are

Cet article analyse l’intérêt et le rôle des oligo-éléments comme facteurs favorisant la croissance pondérale ou osseuse et la défense immunitaire du poulet de chair. L’objectif est d’analyser les conséquences de leur supplémentation à des doses correspondant au besoin de croissance ou à des apports très supérieurs, une pratique actuellement remise en question par la législation afin de limiter le rejet des oligo-éléments dans l’environnement. Des excès de Zn, Fe ou Mn n’ont pas d’effet positif sur la croissance du poulet de chair. Une concentration élevée de Cu (100 à 250 mg/kg) dans l’aliment tend à améliorer légèrement la croissance, mais est à l’origine d’une accumulation de Cu néfaste pour l’environnement dans les zones de production intensive. Zn, Se, Cu et Fe sont des éléments essentiels pour le bon fonctionnement du système immunitaire chez l’oiseau. Les infections et la coccidiose affectent leur métabolisme ce qui peut nécessiter une correction par voie alimentaire. Les ultra-oligo-éléments (Al, Se, Bo, Cd, Cr, F, I, Si, V…) peuvent jouer un rôle important chez des poussins soumis à divers stress nutritionnels, ou se révéler toxiques lorsqu’ils sont utilisés en excès., Trace elements as related to growth and health in chickens This review summarizes the interest and the role of trace element factors favouring body weight or bone growth and the immune response in poultry. The aim is to analyse consequences of supplementation in diets at levels corresponding or higher than the growth requirement for optimising performance of broilers; especially as the use of high dietary levels of trace elements is currently questioned to protect the environment. Cu shows a slight growth promoting effect on chick growth when added at high concentrations, but Zn, Fe or Mn do not. However, such high dietary level can be deleterious for the environment in areas of intensive production. Zn, Se, Cu and Fe are essential elements for the immune system but there is no clear evidence that high dietary levels stimulate the immune response Infection and coccidiosis affect trace mineral metabolism and, therefore, may need nutritional adjustment. Ultra-trace element (Al, Se, Bo, Cd, Cr, F, I, Si, V.) can be of nutritional importance for chicks submitted to some nutritional stress or, when in excess, can be toxic.

National audience

International audience; Introduction Atmospheric deposition is an important input of major nutrients into forest ecosystems. The long-term goal of this work was to apply stable isotope methodology to assess atmospheric nutrient deposition in forest systems. Materials and methods A labelling experiment of foliage with stable isotopes of primary and secondary macro nutrients (N-15, Mg-26 and Ca-42 injected into the stem sapwood) was carried on standing trees to monitor interactions between canopy and precipitations. N-15 rapidly reached the foliage; however, Mg and Ca were not detected in foliage until more than a year after injection. Results and discussion The delay in mobilization of Mg and Ca prevented us from accurately modelling deposition contributions of these two elements. Nonetheless, an upscaling approach based on published results on Ca transport in shoots xylem was used to simulate our results. These simulations of Ca transport at the tree scale were consistent with our experimental data. Conclusion This consistency suggested that mechanisms of nutrient transport are the same at the different scales. Nitrogen was rapidly transported in the xylem to foliage, probably mainly by mass flow. Conversely, transport of Mg and particularly Ca was considerably delayed, probably due to successive cation exchanges along the xylem vessels.

Environmental effects of the excess of P from manure and the soaring price of phosphates are major issues in pig production. To optimize P utilization, it is crucial to improve our capacity to predict the amount of P absorbed, while taking into account the main factors of variation. Mathematical modeling can represent the complexity of the processes and interactions in determining the digestive utilization of phosphorus in growing pigs. This paper describes and evaluates a model developed to simulate the fate of the dietary forms of P in the digestive tract of growing pigs, with particular emphasis on the impact of dietary Ca and exogenous phytase on P digestive utilization. The model consists of 3 compartments associated with specific anatomical sections: stomach, proximal small intestine, and distal small intestine. The main metabolic processes occurring in these sections are, respectively, P solubilization/insolubilization and phytate P hydrolysis, and P absorption and P insolubilization. Model parameters governing these flows were derived from in vitro and in vivo literature data. The sensitivity analysis revealed that the model was stable within a large range of model parameter values (± 1.5 SD). The model was able to predict the efficacy of Aspergillus niger microbial phytase in accordance with literature values, as well as the lower efficacy of plant phytase compared to microbial phytase. The prediction capabilities of the model were assessed by comparing actual and simulated P and Ca apparent total tract digestibility (ATTD) based on published pig data not used for model development. Prediction of P digestibility across 66 experiments and 281 observations was adequate [P ATTD observed = 0.24 (SE, 0.943 + 0.98 (SE, 0.0196) × P ATTD predicted; R2, 0.90; disturbance error (ED), 3.1%], whereas prediction of Ca digestibility across 47 experiments and 193 observations was less accurate (Ca ATTD observed = 11.1 + 0.75 × Ca ATTD predicted; R2, 0.78; ED, 71.3%). The lack of agreement between experimental and simulated Ca digestibility was found. This model is, therefore, useful in evaluating P digestibility for different feedstuffs and feeding strategies. It can also be used to provide insight for improving dietary P utilization, especially from plant sources, by quantifying the impact of the mean sources of variation affecting P utilization.

The major cations in milk are calcium, magnesium, sodium, and potassium and the main anions are inorganic phosphate, citrate, and chloride. This article first discusses the composition and distribution of these ions between the aqueous and micellar phases of milk (named salt equilibria). It then describes the variations in the salt equilibria as a function of physico-chemical conditions (acidification, alkalinization, thermal treatments, cooling, and additions of chelatants, NaCl, and calcium salts). Finally, sample preparation and some analytical methods to determine their content and repartition in milk are described.

Dans les produits laitiers, le calcium est présent en grande quantité. Dans le lait, sa concentration est d’environ 30 mM. Il est en partie associé aux protéines et notamment aux caséines et à d’autres ions comme le phosphate et le citrate. Une autre part de ce calcium (environ 2 mM) appelée calcium ionique (Ca 2+ ) est libre. La concentration de ce calcium ionique évolue en fonction des traitements technologiques (traitement thermique, refroidissement, pH, addition de sels ou de chélatants du calcium) et il est intéressant d’évaluer cette concentration dans une démarche de rech erche, de développement ou de fabrication de produits laitiers. L’objectif de ce travail était de mettre au point le dosage du calcium ionique par une électrode à membrane spécifique sur différents produits laitiers liquides (différents laits et filtrats de laits). La mise au point de la méthode a consisté à réaliser différentes gammes d’étalonnage (entre 0 et 50 mM calcium) dans différentes conditions (agitation, température, présence de magnésium) puis de valider cette méthode sur différents produits lait iers en réalisant des profils d’exactitude. L’étude de différents paramètres d’étalonnage a permis l’obtention d’une gamme d’étalonnage linéaire, répétable, robuste et spécifique. L’établissement de profils d’exactitude a montré que la méthode était valide sur les différents produits laitiers testés. Les résultats obtenus étaient conformes à la littérature avec des concentrations en Ca 2+ comprises entre 1,3 et 2,3 mM et une incertitude de mesure évaluée à environ 15%. Cette méthode qui a l’avantage d’être relativement simple à mettre en œuvre est actuellement utilisée dans notre laboratoire

International audience; Heavy metals are known to generate reactive oxygen species that lead to the oxidation and fragmentation of proteins, which become toxic when accumulated in the cell. In this study, we investigated the role of the proteasome during cadmium stress in the leaves of Arabidopsis thaliana plants. Using biochemical and proteomics approaches, we present the first evidence of an active proteasome pathway in plants. We identified and characterized the peptidases acting sequentially downstream from the proteasome in animal cells as follows: tripeptidyl-peptidase II, thimet oligopeptidase, and leucine aminopeptidase. We investigated the proteasome proteolytic pathway response in the leaves of 6-week-old A. thaliana plants grown hydroponically for 24, 48, and 144 h in the presence or absence of 50 mum cadmium. The gene expression and proteolytic activity of the proteasome and the different proteases of the pathway were found to be up-regulated in response to cadmium. In an in vitro assay, oxidized bovine serum albumin and lysozyme were more readily degraded in the presence of 20 S proteasome and tripeptidyl-peptidase II than their nonoxidized form, suggesting that oxidized proteins are preferentially degraded by the Arabidopsis 20 S proteasome pathway. These results show that, in response to cadmium, the 20 S proteasome proteolytic pathway is up-regulated at both RNA and activity levels in Arabidopsis leaves and may play a role in degrading oxidized proteins generated by the stress.

Metmyoglobin (MbFe III ), a major form of dietary iron, is an efficient inducer of lipid and protein oxidation. Indeed, MbFe III is able to cleave hydrogen peroxide and lipid hydroperoxides with subsequent formation of ferrylmyoglobin (MbFe IV = O) and lipid oxyl and peroxyl radicals. In the first part of this work, the mechanism of the reaction between MbFe III and H 2 O 2 is revisited with an emphasis on the influence of bovine serum albumin (BSA). BSA does not affect the rate of MbFe IV = O formation but inhibits the formation of a redox-inactive green pigment (heme-protein cross-link species). Although tightly bound to BSA, the flavonol quercetin is still able to reduce MbFe IV = O as a likely result of long-range electron transfers within a protein–protein complex. In the second part, BSA is shown to strongly slow down the metmyoglobin-catalyzed consumption of linoleic acid hydroperoxides with formation of ketones as the main products. In the process, only low concentrations of ferrylmyoglobin are slowly accumulated. A catalytic mechanism is proposed that involves a one-electron-oxidized metmyoglobin species distinct from ferrylmyoglobin.

Two decades after the launching of the monitoring program of forest ecosystems in Europe (ICP forests), a unique data set is now available regarding the foliar nutritional status of the main broadleaved species growing in much-diversified sites (soil, climate). This study focuses on the foliar concentration time series (1993 to 2005) of the French (RENECOFOR), Walloon and Luxemburg broad-leaved plots. The aim is to show long-term trends while taking the inter-plot and inter-annual variability into account. Two kinds of statistical processing were used to analyze the data on foliar chemistry: principal component analysis (PCAs) and linear mixed models. In general, the main temporal trends reveal a decrease in the foliar P concentration and a decrease in the foliar Ca concentration, except for European beech on acid soils. These temporal patterns confirm the trends previously observed and could be explained by the joint actions of several processes that influence tree nutrition in the long term: tree age, N and S deposition, harvesting and climate., Deux décennies après le lancement du programme de suivi des écosystèmes forestiers en Europe (ICP forests), un jeu de données unique est à présent disponible concernant le statut nutritionnel foliaire des principales essences feuillues implantées dans des stations très diversifies du point de vue du sol et du climat. Cette étude se focalise sur les séries chronologiques de teneurs foliaires (1993 à 2005) des placettes de feuillus de France, Wallonie et Luxembourg. L’objectif est de mettre en évidence la tendance à long-terme tout en prenant en compte la variabilité inter-placette et inter annuelle. Deux types de traitements statistiques ont été utilisés pour analyser les données de nutrition foliaire : l’analyse en composantes principales (ACP) et les modèles linéaires mixtes. Globalement, la tendance principale est une diminution généralisée de la teneur foliaire en P and une diminution de la teneur foliaire en Ca, sauf en ce qui concerne le hêtre sur sols acides. Ces tendances temporelles confirment celles déjà observées par le passé et pourraient être expliquées par l’action combinée de différents processus influençant la nutrition des arbres à long-terme (vieillissement, dépôts azotés et soufrés, exploitation, fructification).

Abstract – This study aimed at understanding the role of colloidal calcium phosphate (CCP) in acid gelation of milk. Milks were depleted in Calcium (Ca) by dialysis against milk permeate containing a cation-exchange resin. Dialysed milks were then heated (90 °C-10 min) and acidgelled at 42 °C with a yoghurt culture. Minerals, total and soluble protein contents, pH and optical density were measured in unheated and heated dialysed milk, together with diameters and ζ-potentials of particles. Dialysis of milk led to a dissociation of 45% total Ca and 30% total phosphorus, to an increase in sodium content and pH of milk, to lower turbidity and ξ-potential, but did not change the casein particle size. Soluble Ca and casein-bound Ca were removed from milk, CCP being removed increasingly, while Ca removed from the phosphoserine residues increased very little during the dialysis experiments. Maximal dissociation of αs1- and αs2-casein was 20%, while that of β- and κ-casein was 35–40% of total at the end of dialysis, and it increased after heating, especially for κ-casein. The pH value at which the milk sample begins to gel increased for low mineral depletion rates but decreased for higher depletion levels. This was due to the increase in the pH value of milk and in the κ-casein dissociation. The elastic modulus decreased in samples at the lowest depletion and then levelled off, which suggested that the phosphoserine-bound Ca played a critical role in the formation of acid gels.

Trace elements and minerals influence the pathogenesis of obesity and diabetes and their complications, mainly through their involvement in peroxidation and inflammation. On the other hand, peroxidation and inflammation are liable to alter themetabolismof these nutrients, which should be taken into account when assessing their status. Milk products are capable of preventing iron-induced peroxidation and the metabolic complications of the diseases. Calcium, especially cow milk calcium, seems to be capable of preventing the development of adipocytes and obesity complications (inflammation, hypertension, and insulin resistance), mainly through interactions with vitamin D metabolism. These observations give an opportunity to influence the course of obesity by dietetic advices.

Stand harvesting and regeneration were usually considered to be a critical phase for the sustainability of forest soils. The present study concerned the effects on soil chemical fertility of the clear-cutting of a highly productive Douglas-fir stand aged 67 years that was clear-cut with no disturbance. Results showed that soil changes were rapid in the three-year period following the cutting. The forest floor mass considerably decreased and the mineral soil showed a limited but real acidification. Soil losses represented 4% of the available nutrients over a depth of 60 cm for N, 22% for K, 25% for Ca and 32% for Mg. Only P increased by 11%. Due to the spatial variability of forest soils, and despite regular re-sampling, confidence intervals were large and difficult to reduce. The reversibility of the effects of the clear-cutting and its consequences on soil functions depend on the element: it should not be a problem for C, N and K, which would recover when the biological cycle is re-established once again in the young stand. Phosphorus is not at issue since it changes form in the soil. The depletion of Ca, and to a lesser extent of Mg, is of some concern as a result of limited soil reserves, the limited flux of cations from the mineral changes in the soil, the relatively large part of Ca and Mg in the forest floor, and the negative input-output budgets for those elements. The duration of the impact of the clear-cutting on soil requires medium-term observations because it cannot be deduced from the current knowledge of this ecosystem., La récolte des peuplements est une phase critique pour la durabilité des sols forestiers. Cette étude concerne les effets de la coupe à blanc d’un peuplement de Douglas de 67 ans, réalisée sans perturbation, sur la fertilité organo-minérale du sol. Les résultats montrent que l’évolution du sol est rapide dans la période de trois ans après la coupe. La couche organique décroît fortement et le sol minéral se désature et s’acidifie. Les pertes représentent 4 % des éléments disponibles du sol sur 60 cm pour N, 22 % pour K, 25 % pour Ca et 32 % pour Mg. Seul P augmente de 11 %. Cependant, la variabilité spatiale des sols forestiers et la technique de l’observatoire, par échantillonnages successifs, conduisent à des intervalles de confiance larges autour de ces valeurs, intervalles qui s’avèrent difficile à réduire. La réversibilité des modifications du sol dépend des éléments : elle ne devrait pas poser de problème pour C, N et K. P n’est pas en cause puisqu’il change de forme dans le sol mais aucune perte n’est notée. Les pertes de Ca voire de Mg sont les plus préoccupantes en raison des faibles réserves du sol, du flux limité de cations issu de l’altération des minéraux du sol, de la part relativement élevée des ces éléments dans les couches organiques, et de leur bilan entrées-sorties négatif. La durée de l’effet de la coupe à blanc nécessite des observations sur le moyen terme car elle ne peut pas être déduite des connaissances actuelles sur cet écosystème.

In this study, the spatial distribution of nutrient stocks (K, Ca, Mg and P) was examined in humus and soils at the forest massif scale (Fougères forest, France). A random stratified sampling plan including 100 sampling points was used and three potential variation factors of nutrient stocks were tested: age of stand, type of stand (broad-leaved or coniferous trees) and type of soil. Sampling classes were then compared and the variation factors were examined. Results demonstrated that nutrient stocks in the humus were not influenced by the cited factors and only the type of soil influenced nutrient stocks in soils. In fact, stocks of exchangeable elements in soils were much higher in Colluviosols-Fluviosols which show redoximorphic characteristics, and available phosphorus stocks were lower than in Alocrisols-Neoluvisols. Moreover, a low variability of nutrient stocks was observed in Alocrisols-Neoluvisols as opposed to Colluviosols-Fluviosols, which may suggest the existence of other variation factors not taken into account in this study (hydromorphic gradient, type and age of stand in hydromorphic zones)., Dans ce travail, la distribution spatiale des réserves de nutriments (K, Ca et Mg et P) dans les sols et les humus a été étudiée à l’échelle d’un massif forestier (Forêt de Fougères, France). Un plan d’échantillonnage aléatoire stratifié regroupant 100 sites a été utilisé et trois facteurs potentiels de variation des stocks de nutriments ont été testés : âge et type de peuplements (feuillus et résineux) et type de sol. Les classes d’échantillonnage ont ensuite été comparées et les facteurs de variation des stocks examinés. Les résultats montrent que les réserves de nutriments dans les humus ne sont pas influencées par les facteurs cités précédemment alors que seul le type de sol influence les réserves dans les sols. Les stocks de nutriments échangeables dans les sols sont en effet significativement plus élevés et les stocks de phosphore assimilable plus faibles dans les Colluviosols-Fluviosols à caractère hydromorphe en comparaison des Alocrisols-Néoluvisols. De plus, la variabilité des stocks pour les Alocrisols-Néoluvisols est faible en comparaison des Colluviosols- Fluviosols, ce qui suggère l’existence d’autres facteurs de variation non pris en compte lors de l’étude (gradient d’hydromorphie, type et âge des peuplements dans les zones hydromorphes).

Protein protection against iron induced intestinal peroxidation and carcinogenesis in rats: a preliminary report

International audience; Phosvitin, an egg yolk protein constituted by 50% of phosphorylated serines, presents good emulsifying properties whereas its interfacial properties are not yet clearly elucidated and remain object of discussion. Phosvitin has a high charge density and naturally forms aggregates through phosphocalcic bridges in egg yolk. This high charge density, doubled by this capacity to aggregate, limits the adsorption of the protein at the air-water interface. In this work, we investigated the aggregation impact by calcium ions on the organization of the phosvitin interfacial film using the atomic force microscopy. Phosvitin interfacial films without calcium ions are compared to phosvitin interfacial films formed in the presence of calcium ions in the subphase. We demonstrated that phosvitin is able to anchor at air-water interfaces in spite of its numerous negative charges. In the compression isotherm a transition was observed just before 28 mN/m signifying a possible modification of the interfacial film structure or organization. Calcium ions induce a reorganization towards a greater compaction of the phosvitin interfacial film even at low surface pressure. In conclusion we suggest that, in diluted regime, phosvitin molecules could adsorb by their two hydrophobic extremities exhibiting loops in the aqueous phase, whereas in concentred regime (high interfacial concentration) it would be adsorbed at the interface by only one extremity (brush model).

National audience

The use of spray drying for dehydration of acid whey is generally limited by the appearance of uncontrolled thickening and solidifying of the whey mass during the lactose crystallization step. The origin of this physical change is still unknown and probably linked to complex interactions between physical properties and chemical composition of these products. To understand this phenomenon, we simulated the thickening of concentrated acid whey on a laboratory scale by measuring the flow resistance changes as a function of time and whey composition. The thickening process was characterized by an amplitude of torque and a lag time (induction time). Thickening of lactic acid whey concentrate occurred regardless of the presence of whey proteins or lactose crystals. Moreover, this work clearly demonstrated that the thickening process was due to the formation of filamentous structures corresponding to calcium lactate crystals and showed a large dependence on calcium and lactate contents, pH, and phosphate concentration.

Ferritins play an essential role in iron homeostasis by sequestering iron in a bioavailable and non-toxic form. In plants, ferritin mRNAs are highly and quickly accumulated in response to iron overload. Such accumulation leads to a subsequent ferritin protein synthesis and iron storage, thus avoiding oxidative stress to take place. By combining pharmacological and imaging approaches in an Arabidopsis cell culture system, we have identified several elements in the signal transduction pathway leading to the increase of AtFer1 transcript level after iron treatment. Nitric oxide quickly accumulates in the plastids after iron treatment. This compound acts downstream of iron and upstream of a PP2A-type phosphatase to promote an increase of AtFer1 mRNA level. The AtFer1 gene transcription has been previously shown to be repressed under low iron conditions with the involvement of the cis-acting element iron-dependent regulatory sequence identified within the AtFer1 promoter sequence. We show here that the repressor is unlikely a transcription factor directly bound to the iron-dependent regulatory sequence; such a repressor is ubiquitinated upon iron treatment and subsequently degraded through a 26 S proteasome-dependent pathway.

Background: Peptides derived from cow’s milk proteins have in vitro protective effects on iron-induced peroxidation that could be used to prevent the side effects of iron fortification. The aim of the study was to confirm these properties in an in vivo model of gut peroxidation. Methods: Iron bound to the 1–25 phosphopeptide of β-casein [Fe-β-CPP(1–25)] was compared to an encapsulated ferric pyrophosphate (Fe-P) in the Caco-2 model. Ferrous sulfate (FeSO4) was used as control (100 µmol/l iron, n = 6 per group). The concentration of malondialdehyde (MDA), a stable byproduct of lipid peroxidation, was used as the marker of peroxidation. Results: The lowest MDA levels were observed in cells grown with Fe-β-CPP(1–25) and the highest with Fe-P. Iron absorption of Fe-β-CPP(1–25) was higher than in the 2 other forms, due to its high cellular uptake and high basolateral transfer, while iron absorption of Fe-P showed high uptake and high cell retention. Conclusions: The enhancing effect of β-CPP(1–25) on iron absorption was associated with a protective effect against enterocyte peroxidation, perhaps due to its low storage by enterocytes. These observations support a role for specific milk components in food fortification to prevent iron deficiency.

Lipid peroxidation stress induced by iron supplementation can contribute to the induction of gut lesions. Intensive sports lead to ischemia reperfusion, which increases free radical production. Athletes frequently use heavy iron supplementation, whose effects are unknown. On the other hand, milk proteins have in vitro antioxidant properties, which could counteract these potential side effects. The main aims of the study were: (1) to demonstrate the effects of combined exercise training (ET) and iron overload on antioxidant status; (2) to assess the protective properties of casein in vivo; (3) to study the mechanisms involved in an in vitro model. Antioxidant status was assessed by measuring the activity of antioxidant enzymes (superoxide dismutase (SOD); glutathione peroxidase (GSH-Px)), and on the onset of aberrant crypts (AC) in colon, which can be induced by lipid peroxidation. At day 30, all ET animals showed an increase in the activity of antioxidant enzymes, in iron concentration in colon mucosa and liver and in the number of AC compared to untrained rats. It was found that Casein's milk protein supplementation significantly reduced these parameters. Additional information on protective effect of casein was provided by measuring the extent of TBARS formation during iron/ascorbate-induced oxidation of liposomes. Free casein and casein bound to iron were found to significantly reduce iron-induced lipid peroxidation. The results of the overall study suggest that Iron supplementation during intensive sport training would decrease anti-oxidant status. Dietary milk protein supplementation could at least partly prevent occurrence of deleterious effects to tissue induced by iron overload.

Clusters of phosphoserine residues in cow milk caseins bind iron (Fe) with high affinity. Casein inhibits Fe absorption in humans, but protein hydrolysis lessens this effect. Phosphopeptides from different caseins gave conflicting results on Fe absorption; release of phosphate residues by intestinal alkaline phosphatase could be a key point of that metabolism. The objectives of this study were to compare the absorption of Fe complexed to caseinophosphopeptides (CPP) of the main cow milk caseins β-casein (β-CPP) and αs-caseins (αs1-CPP) and to assess the role of alkaline phosphatase on this absorption. Two experimental models were used: an in vivo perfused rat intestinal loop and an in vitro Caco-2 cell culture model. In addition, we determined the effect of an intestinal phosphatase inhibitor on these various forms of Fe. Gluconate Fe was used as control. In both models, uptake and net absorption of Fe complexed to CPP from αS1-caseins were significantly lower than from Fe complexed to β-CPP. Inhibition of the intestinal phosphatase significantly increased the uptake and the absorption of Fe complexed to β-CPP without effect on the other forms of Fe. These results confirm the enhancing effect of β-casein and its CPP on Fe absorption. The differences between CPP could be explained by their structural and/or conformational features: binding Fe to αS1-CPP could impair access to digestive enzymes, whereas β-CPP-bound Fe is better absorbed than its free form. The differences in protein composition between cow and breast milk, which does not contain α-casein, could explain some of their differences in Fe bioavailability. Abbreviations: CPP, caseinophosphopeptides Fe, iron Iron (Fe) deficiency is one of the most common nutritional problems around the world, both in developed and in developing countries. It is responsible for a long-lasting impairment of neurologic development in infants; Fe is also essential for immunity and growth (1,2). Cow milk products and cow milk-based infant formulas are two main components of infant diet; however, Fe absorption from cow milk is low compared with breast milk (3); the high calcium concentration and the kind of proteins of cow milk could explain these differences (4,5). The main cow milk proteins are caseins, which bind cations, including Fe, by clusters of phosphoserine (6,7). This strong binding keeps Fe soluble at the alkaline gut pH but prevents its release in a free form available for absorption by the duodenal mucosa (8). Hydrolysis of whole caseins improves Fe absorption (5), but caseinophosphopeptides (CPP) released by the enzyme digestion of different caseins give conflicting results; the two main cow milk caseins are αS- and β-caseins; binding Fe to CPP of β-casein or to hydrolyzed β-casein improves its absorption and its bioavailability in rats and in humans (9-11); however, CPP derived from the hydrolysis of whole casein or fractions enriched with αS-casein CPP inhibit Fe absorption (12-14). One of the key steps of the absorption of CPP-bound Fe seems to be the release of phosphoserine residues by brush border phosphatase: it could be assumed that releasing free Fe could increase its absorption from a poorly absorbed form; however, releasing Fe from a stable, efficiently absorbed complex, such as Fe-βCPP (1-25) could impair its absorption by increasing the amount of free Fe subject to gut interactions. These functional differences between caseins and casein-derived CPP could give some clues to improve the bioavailability of cow milk Fe. The objectives of this study were to evaluate the absorption of Fe complexed to CPP purified either from β-casein or from αs1-casein and to determine the effect of an inhibitor of intestinal alkaline phosphatase (Na2WO4) (12,15). The study used two models, the in vivo perfused rat intestinal loop and a human colon adenocarcinoma cell line culture (Caco-2), which is predictive of human Fe bioavailability (16).

Hydrolysis of proteins could lessen their inhibiting effect on the poor absorption of cow's milk iron (Fe), which is responsible for the high incidence of Fe deficiency worldwide. When bound to Fe, caseinophosphopeptides (CPP) derived from milk proteins resist luminal digestion, enhance Fe solubility and could improve its bioavailability; brush border enzyme alkaline phosphatase activity could influence iron absorption by releasing free Fe; this study assessed its role in the absorption of CPP-bound Fe. Rat duodenal loops were perfused with Fe gluconate or Fe bound to the CPP of beta casein [beta-CN (1-25)], with or without the addition of an inhibitor of alkaline phosphatase, Na2WO4. The uptake of Fe-beta-CN (1-25) was greater than Fe gluconate. Na2WO4 enhanced the uptake of Fe-beta-CN (1-25) and not of Fe gluconate. So the release of free, insoluble Fe, by alkaline phosphatase seems to be prevented by providing Fe in the Fe-beta-CN (1-25) complex form. Its good disappearance rate makes beta-CN (1-25)-bound Fe a candidate for food fortification.

Background previous studies have shown that non-digestible inulin-type fructan intake can increase intestinal mineral absorption in both humans and animals. However, this stimulatory effect on intestinal absorption may depend on experimental conditions such as duration of fermentable fiber intake, mineral diet levels and animals' physiological status, in particular their age. Objectives the aim of this study was to determine the effect of inulin intake on Ca and Mg absorption in rats at different age stages. Methods eighty male Wistar rats of four different ages (2, 5, 10 and 20 months) were randomized into either a control group or a group receiving 3.75% inulin in their diet for 4 days and then 7.5% inulin for three weeks. The animals were fed fresh food and water ad libitum for the duration of the experiment. Intestinal absorption of Ca and Mg was determined by fecal monitoring using stable isotopic tracers. Ca and Mg status was also assessed. Results absorption of Ca and Mg was significantly lower in the aged rats (10 and 20 mo) than in the young and adult rat groups. As expected, inulin intake increased Ca and Mg absorption in all four rat groups. However, inulin had a numerically greater effect on Ca absorption in aged rats than in younger rats whereas its effect on Mg absorption remained similar across all four rat age groups. Conclusion the extent of the stimulatory effect of inulin on absorption of Ca may differ according to animal ages. Further studies are required to explore this effect over longer inulin intake periods, and to confirm these results in humans.

International audience; La faisabilité technique de l'agriculture biologique (AB) en Martinique repose sur les mêmes champs d'intervention que dans les espaces tempérés : les rotations culturales (3.1), les techniques de travail du sol (3.2), la disponibilité de semences et plants agréés (3.3), le contrôle de la santé des plantes (3.4), la fertilisation et la gestion de la matière organique (3.5), la gestion des « mauvaises herbes » (3.6). Tout en étant des facteurs décisifs pour la production agrobiologique, ils sont pour chacun d'entre eux encadrés par un cahier des charges prédéfini dans des conditions adaptées aux espaces tempérés, et laissant peu de marges de manoeuvre dans les espaces tropicaux aux contraintes particulières. L'élevage (3.7) est en particulier une des clés de la mise en oeuvre de rotations et de la fourniture de sous-produits organiques permettant de maintenir le statut organique des sols et de fertiliser les cultures en AB. Dans le cadre de l’agriculture agroécologique (AE)1 , les grands principes développés ici peuvent être intégralement repris, mais dans le détail les techniques à mettre en œuvre peuvent être plus facilement adaptées aux contraintes locales. Au-delà des faits et mécanismes attestés par des publications, du reste peu nombreuses, les auteurs de ce chapitre ont choisi de mentionner les résultats de leur expérience ou le fruit de leurs réflexions sur les conditions techniques des cultures aux Antilles.

The aim of this work was to study, in a rhizobox experiment, the phytoextraction of metals by the hyperaccumulator plant Thlaspi caerulescens in relation to the heterogeneity of metal pollution. Six treatments were designed with soils containing various levels of metals. Homogeneous soils and inclusions of soils in other soil matrices were prepared in order to vary metal concentration and localization. Growth parameters of the plant (rosette diameter and shoot biomass) and localization of roots and shoot uptake of Zn, Cd, Ca, and Mg were determined after 10 weeks of growth. The plants grown on the polluted industrial soils provided a larger biomass and had lower mortality rates than those grown on the agricultural soil. Moreover, these plants accumulated more Zn and Cd (up to 17,516 and 375 mg kg(-1) DM, respectively) than plants grown on the agricultural soil (up to 7300 mg Zn kg(-1) and 83 mg Cd kg(-1) DM). The roots preferentially explored metal-contaminated areas. The exploration of polluted soil inclusions by the roots was associated with a higher extraction of metals. Zinc and Cd in the shoots of Thlaspi caerulescens were negatively correlated with Ca and Mg concentrations; however, the soil supply for these two elements was identical. This suggests that there is competition for the uptake of these elements and that Zn is preferentially accumulated.

Molecular and cellular mechanisms underlying the sustained metal tolerance of ectomycorrhizal fungi are largely unknown. Some of the main mechanisms involved in metal detoxification appear to involve the chelation of metal ions in the cytosol with thiol-containing compounds, such as glutathione, phytochelatins, or metallothioneins. We used an improved high-performance liquid chromatography method for the simultaneous measurement of thiol-containing compounds from cysteine and its derivatives (γ-glutamylcysteine, glutathione) to higher-molecular-mass compounds (phytochelatins). We found that glutathione and γ-glutamylcysteine contents increased when the ectomycorrhizal fungus Paxillus involutus was exposed to cadmium. An additional compound with a 3-kDa molecular mass, most probably related to a metallothionein, increased drastically in mycelia exposed to cadmium. The relative lack of phytochelatins and the presence of a putative metallothionein suggest that ectomycorrhizal fungi may use a different means to tolerate heavy metals, such as Cd, than do their plant hosts.

Le zinc est un oligo-élément essentiel qui intervient dans la plupart des fonctions biologiques de l’animal. La perte d’appétit, la diarrhée, le retard de croissance ou la parakératose sont les principaux symptômes d’une carence en zinc qui peuvent apparaître chez le porc recevant une alimentation non supplémentée en zinc. La méconnaissance des besoins en zinc du porc et des facteurs de variation de sa disponibilité conduit à l’incorporer de manière excessive dans les aliments. Cette pratique génère des rejets importants et augmente le risque de pollution des sols cultivés. L’ajustement des apports de zinc aux besoins de l’animal et l’amélioration de sa disponibilité sont des solutions qui permettent d’en réduire les apports. Une revue des données de la littérature nous permet d’estimer les besoins en zinc du porc en fonction du poids vif. L’utilisation d’additifs, notamment de phytase microbienne, permet d’améliorer la disponibilité du zinc. A partir des résultats de la littérature, nous estimons que l’activité de 1000 unités de phytase microbienne par kg d’aliment est équivalente à une addition de 24 et 19 mg/kg de zinc sous forme de sulfate chez le porcelet de respectivement 15 et 25 kg. Ces estimations sont à valider expérimentalement. D’autres voies d’amélioration de la disponibilité du zinc doivent également être explorées., Zinc is an essential trace element which plays a rolein many biological functions. Loss of appetite, diarrhoea, growth retardation or parakeratosis are symptoms of zinc deficiency that occure in pigs fed non zinc supplemented diets. Due to a lack of knowledge of both the actual zinc requirements of pigs and the factors that affect its availability in pigs, this element is often oversupplied in pig feeding. Such a practice has a direct adverse effect on the environment, particularly in areas of intensive pig farming. To overcome this problem and avoid any wastage of dietary zinc, the supply should be better adjusted to the requirements and zinc availability should be improved as much as possible.Relying on a literature review, pig zinc requirements were estimated according to body weight. The addition of phytase improves zinc bio availability and 1000 units of microbial phytase /kg of diet were estimated to be equivalent to the addition of 24 and 19 mg /kg zinc added as zinc sulphate in the diets of piglets weighing 15 kg and 25 kg, respectively. Such estimates are worth being validated experimentally. Moreover, the actual impact of other dietary components on zinc availability remains to be assessed.

International audience; Les symptômes foliaires, les analyses mycologiques, les analyses foliaires et les analyses de sol révèlent une carence en bore dans deux plantations de Cèdre de l'Atlas (Cedrus atlantica Man.) âgées de 15 ans et situées sur des sols gneissiques du Massif central.