Recent advances in exploring physiology and biodiversity of ectomycorrhizas highlight the functioning of these symbioses in ecosystems

Ectomycorrhizas, the dominating mycorrhizal symbiosis in boreal, temperate and some tropical forests, are formed by 5000-6000 species of the asco- and basidiomycetes. This high diversity of fungal partners allows optimal foraging and mobilisation of various nitrogen and phosphorus forms from organic soil layers. In this review, two approaches to study the functioning of this multitude of symbiotic associations are presented. On selected culture models, physiological and molecular investigations have shown that the supply of hexoses has a key function in controlling the plant^fungus interaction via partner-specific regulation of gene expression. Environmental factors which affect fungal carbon supply, such as increased nitrogen availability, also affect mycorrhiza formation. Based on such laboratory results, the adaptative capability of ectomycorrhizas to changing field conditions is discussed. The second approach consists of analysing the distribution of mycorrhizas in ecosystem compartments and to relate distribution patterns to variations of ecological factors. Recent advances in identification of fungal partners in ectomycorrhizas by analysing the internal transcribed spacer of ribosomal DNA are presented, which can help to resolve sampling problems in field studies. The limits of the laboratory and the field approaches are discussed. Despite some problems, this combined approach is the most promising. Direct investigation of gene expression, which has been introduced for soil bacteria, will be difficult in the case of mycorrhizal fungi which constitute organisms with functionally varying structure

Electroactivity of phototrophic river biofilms and constitutive cultivable bacteria

Electroactivity is a property of microorganisms assembled in biofilms that has been highlighted in a variety of environments. This characteristic was assessed for phototrophic river biofilms at the community scale and at the bacterial population scale. At the community scale, electroactivity was evaluated on stainless steel and copper alloy coupons used both as biofilm colonization supports and as working electrodes. At the population scale, the ability of environmental bacterial strains to catalyze oxygen reduction was assessed by cyclic voltammetry. Our data demonstrate that phototrophic river biofilm development on the electrodes, measured by dry mass and chlorophyll a content, resulted in significant increases of the recorded potentials, with potentials of up to +120 mV/saturated calomel electrode (SCE) on stainless steel electrodes and +60 mV/SCE on copper electrodes. Thirty-two bacterial strains isolated from natural phototrophic river biofilms were tested by cyclic voltammetry. Twenty-five were able to catalyze oxygen reduction, with shifts of potential ranging from 0.06 to 0.23 V, cathodic peak potentials ranging from −0.36 to −0.76 V/SCE, and peak amplitudes ranging from −9.5 to −19.4 μA. These isolates were diversified phylogenetically (Actinobacteria, Firmicutes, Bacteroidetes, and Alpha-, Beta-, and Gammaproteobacteria) and exhibited various phenotypic properties (Gram stain, oxidase, and catalase characteristics). These data suggest that phototrophic river biofilm communities and/or most of their constitutive bacterial populations present the ability to promote electronic exchange with a metallic electrode, supporting the following possibilities: (i) development of electrochemistry-based sensors allowing in situ phototrophic river biofilm detection and (ii) production of microbial fuel cell inocula under oligotrophic conditions

Rotating disk electrodes to assess river biofilm thickness and elasticity

The present study examined the relevance of an electrochemical method based on a rotating disk electrode (RDE) to assess river biofilm thickness and elasticity. An in situ colonisation experiment in the River Garonne (France) in August 2009 sought to obtain natural river biofilms exhibiting differentiated architecture. A constricted pipe providing two contrasted flow conditions (about 0.1 and 0.45 m s−1 in inflow and constricted sections respectively) and containing 24 RDE was immersed in the river for 21 days. Biofilm thickness and elasticity were quantified using an electrochemical assay on 7 and 21 days old RDE-grown biofilms (t7 and t21, respectively). Biofilm thickness was affected by colonisation length and flow conditions and ranged from 36 ± 15 μm (mean ± standard deviation, n = 6) in the fast flow section at t7 to 340 ± 140 μm (n = 3) in the slow flow section at t21. Comparing the electrochemical signal to stereomicroscopic estimates of biofilms thickness indicated that the method consistently allowed (i) to detect early biofilm colonisation in the river and (ii) to measure biofilm thickness of up to a few hundred μm. Biofilm elasticity, i.e. biofilm squeeze by hydrodynamic constraint, was significantly higher in the slow (1300 ± 480 μm rpm1/2, n = 8) than in the fast flow sections (790 ± 350 μm rpm1/2, n = 11). Diatom and bacterial density, and biofilm-covered RDE surface analyses (i) confirmed that microbial accrual resulted in biofilm formation on the RDE surface, and (ii) indicated that thickness and elasticity represent useful integrative parameters of biofilm architecture that could be measured on natural river assemblages using the proposed electrochemical method

La distinction aux champs. Les décorés du Mérite agricole (Rhône, 1883-1939)

Cette étude prosopographique analyse les deux dimensions accordées à la décoration du Mérite agricole. Professionnelle, la distinction témoigne des critères de l’excellence agricole formulés par le ministère de l’Agriculture nouvellement créé : apparaît alors la volonté de structurer une filière agricole en récompensant les acteurs de progrès scientifiques ou techniques et d’un enseignement spécifique, en mesure de rendre l’agriculture française plus performante. Au sein des producteurs, elle érige en modèle d’une part les spécialisations agricoles répondant aux attentes du marché et fondées sur la qualité, d’autre part le dévouement au tissu associatif agricole et plus largement rural. Les détracteurs de la décoration expliquent l’importance de ses effectifs par la distinction de soutiens politiques. L’instruction des dossiers de candidature permet de mettre en évidence l’acceptation de la pratique des recommandations et une utilisation circonstanciée par l’administration, en partie en fonction des opinions politiques des élus locaux. De plus, quoique l’opinion des impétrants soit prise en considération, elle n’empêche pas la distinction de membres actifs de syndicats agricoles affiliés à l’Union du Sud-Est.Distinction in the fields. The members of the Order of Agricultural Merit in the department of the Rhône (1883-1939) This study of  a group analyses both dimensions attributed to the decoration of Agricultural Merit. It was a professional distinction pointing to the criteria of farming excellence as they had been formulated by the Agricultural Ministry: the will to structure a farming network by rewarding the promoters of scientific or technical progress or of a specific teaching, so as to make French agriculture more efficient. Among the producers, it raised two trends to the status of models: farming specialisation complying with the expectations of the market and the dedication of the farming association network and more largely rural. Detractors of the decoration explained it was largely given because it was a reward for political support. The study of application files makes it possible to point to acceptation of the practise of patronage and a detailed use by the administration, partly depending on the political opinions of local councillors. Moreover, although the political leanings of the candidates were taken into account, this did not prevent active members of farming unions affiliated to the Union du Sud-Est (Union of the South East) from being decorated

A Review on Membranes for Clinical Treatment and Drug Delivery in Medical Applications

Membrane processes are used extensively in biomedical applications. This state of the art review presents the main applications including renal kidney, blood filtration, blood oxygenator, artificial liver, artificial pancreas, and drug delivery devices. For well-established treatments like dialysis, plasmapheresis, and blood oxygenator, the techniques are summarized by presenting membranes used, devices, configurations and treatments. The artificial liver and the artificial pancreas are not clinically used and some main aspects related to the development of these devices are given, including configurations and liver or pancreatic cells. Finally, drug delivery devices based on membranes, which are an important area in pharmaceutics, are summarized by focusing on diffusion and transdermal delivery systems, as well as colloids like liposomes and nanocapsules. These colloids with nanometric size are surrounded by a lipidic or polymeric thin membrane which controls drug transfer to the surrounding medium

Prévalence et facteurs de risque de surpoids dans une population de jeunes chiens entiers de race pure

L’excès de poids, dont les conséquences sanitaires son lourdes, fait actuellement partie des affections les plus répandues chez le chien. L’objectif de cette étude était de déterminer la prévalence et les facteurs de risque de surpoids dans une population particulièrement médicalisée et peu prédisposée à cette affection. 482 chiens participant à des expositions ou des confirmations ont ainsi été inclus dans ce travail. Leur composition corporelle a été évaluée à l’aide du poids vif et de l’établissement de la note d’état corporel (NEC). Leurs caractéristiques et leur mode de vie ont également été renseignés grâce à un questionnaire adressé aux propriétaires. Au final, 17,6% des chiens étaient en surpoids modéré (NEC = 6/9) et 4,6% en surpoids important (NEC > 6/9). Le poids vif dépassait le poids maximal autorisé par le standard racial chez 25,4% des animaux. Ce travail met donc en évidence la forte prévalence du surpoids parmi des chiens pourtant élevés pour leurs qualités esthétiques. Les facteurs de risque identifiés (P-value < 0,01) étaient le temps de promenade quotidien (inférieur ou égal à 1 heure), le groupe racial (Retrievers et English Spaniels), le sexe (femelles) et le lieu de couchage (intérieur)

Frédéric CHAUVAUD [dir.], La société agricole de la Vienne aux XIXe et XXe siècles. Guide de recherche, La Crèche, Geste éditions, 2001, 331 p.

Sous la direction de Frédéric Chauvaud, historiens, géographes, sociologues, ethnologues, musicologue et archivistes collaborent pour mettre à profit leurs compétences sur les fonds archivistiques du département de la Vienne. Suscité par l’Association pour l’étude de l’histoire de l’agriculture au XXe siècle, ce premier guide de recherche en histoire agricole contemporaine (de 1815 à nos jours) est un instrument de travail conçu pour tous les chercheurs, dans le but de favoriser et de facilit..

Trajectoires municipales au prisme des changements de régime

Au regard des révocations prononcées lors de la première puis au début de la seconde Restauration, une faible épuration est exercée sur les maires et adjoints de la fin du Premier Empire. Cependant, durant les Cent-Jours, les administrés élisent dans la majeure partie des communes des hommes qui avaient été évincés en 1807 ou en 1812 au profit de royalistes issus de l’ancienne noblesse ou encore des hommes nouveaux : une révolution des mairies semble donc s’être produite. La reconstitution des trajectoires de ces hommes montre une réintégration dans une proportion non négligeable. Lorsqu’elle a lieu, la préfecture agit en connaissance de cause, souvent contrainte par les réalités communales, mais en prenant des assurances vis-à-vis de ce personnel qui reste hostile au régime.The dismissals ordered during the first Restoration and the beginning of the second Restoration suggest that a slight purge of mayors and deputy mayors occurred at the end of the First Empire. However, during the Hundred Days, citizens in most townships elected men who had in 1807 or 1812 been ousted in favor of royalists from the old nobility, or of new men entirely, producing a kind of town council revolution. A reconstruction of these men’s careers reveals that a substantial number were reinstated. Where this was the case, the prefectures acted knowingly, often constrained by the local situation, yet careful to take assurances with regard to these employees who remained hostile to the regime

Optimal system management of a water pumping and desalination process supplied with intermittent renewable sources

This paper aims at defining energy management strategy for a water pumping and desalination process which would be powered by a hybrid (solar PV & wind) renewable generation system. Several pumping subsystems for well pumping, water storage and desalination are coupled. The particularity of the proposed architecture with its management deals with the absence of electrochemical storage, only taking benefit of hydraulic storage in water tanks: in such an autonomous device, given a certain level of intermittent power following wind and sun irradiation conditions, and given hydraulic characteristics of water pumping subsystems, this study puts forward the prime importance of a water and power flow management optimization. For this purpose, both dynamic and quasi static models are proposed before stetting the management strategy based on optimal power dispatching. Subsequent results are analyzed in terms of robustness and performance

Microbial dynamics associated with leaves decomposing in the mainstem and floodplain pond of a large river

Aquatic habitats of forested floodplain systems receive large inputs of allochthonous plant litter. We examined the decomposition of, and microbial productivity associated with, leaves of a common floodplain tree, Populus gr. nigra, in the mainstem and floodplain pond of a seventh order river in 2 consecutive years. Litter bags were submerged at both sites, retrieved periodically, and analyzed for litter mass loss, bacterial and fungal biomass, growth rate and production, and sporulation rates of aquatic hyphomycetes. Litter decomposition rates were similar in both sites and years (leaf breakdown coefficients k of 0.0070 to 0.0085 d–1), although microbial dynamics partly differed between sites. Species diversity of aquatic hyphomycetes was lower on leaves submerged in the pond (16 species) than in the river (21 species). Mycelial biomass was also significantly lower in the pond, with values <20 mgCg–1 of detrital C, whereas peaks of 50 and 80 mgC g–1 were reached in leaves in the mainstem. These differences contrast with the comparable fungal productivity at both sites (peak rates of 1.4 mg of mycelial C per g of detrital C per day in both years). This suggests that fungi were equally productive in both habitats but experienced greater losses in the pond. Bacterial numbers and biomass also showed the same basic pattern at both sites, although somewhat higher levels were reached in the pond (maximum of about 10^10 cells and 0.5 mg g–1 of detrital C). Bacterial- specific production rates fluctuated between 0.06 and 1.5 d–1 with lower values occurring in the floodplain pond. Although bacteria on leaves were clearly outweighed by fungi in terms of biomass, they accounted for a sizeable fraction of the total biomass (up to 11%), and up to 32% of the total microbial production. Our comparison of bacterial and fungal productivity thus points to a critical role of fungi in litter decomposition in aquatic habitats of river floodplain systems, while suggesting that bacteria must not be overlooked as important agents of litter decompositon in riverine environments