LES ESCARGOTS BIO-INDICATEURS DE LA QUALITE DES SOLS - Snail watch : analyse en laboratoire ou in situ de la biodisponibilité des contaminants

http://www2.ademe.fr/servlet/KBaseShow?sort=-1&cid=96&m=3&catid=10143fiche outil 4 pagesCe document est une fiche outil présentant les possibilités d'utilisation des escargots pou analyse en laboratoire ou in situ de la biodisponibilité des contaminants. Cette fiche a été mise en ligne sur le site de l'ADEME/ sites pollués et sols/ outils méthodologiques: http://www2.ademe.fr/servlet/KBaseShow?sort=-1&cid=96&m=3&catid=1014

Chemical extractions and predicted free ion activities fail to estimate metal transfer from soil to field land snails.

International audienceThis study investigates the relevance of several soil chemical extractions (calcium chloride, acetic acid, citric acid and a four-step sequential procedure) and predicted free metal ion activities in the soil solution to characterise the transfer of trace metals (Cd, Pb, and Zn) from soil to snail soft tissues over a large smelter-impacted area (Metaleurop Nord, Nord-Pas-de-Calais, France). The study was first performed on six snail species together and then specifically on Cepaea sp. and Oxychilus draparnaudi. When the six species were considered together, the accumulation of metals depended mostly on the species. When significant, total or extractable metal concentrations, or the predicted free ion activities, accounted for less than 7% of the variation of the metal concentrations in the snail tissues. Species-specific analyses showed that extractable concentrations explained approximately 25% of the variation of the metal concentrations in O. draparnaudi, and up to 8% in Cepaea snails. When using total soil concentrations and soil properties as explanatory variables, the models were generally slightly better, explaining up to 42% of the variance. The soil extraction procedures and predicted free ion activities used in this study did not accurately estimate the metal transfer from soil to snails and could not be used in risk assessment

Comparative secretome analyses of two Trichoderma reesei RUT-C30 and CL847 hypersecretory strains

ABSTRACT: BACKGROUND: Due to its capacity to produce large amounts of cellulases, Trichoderma reesei is increasingly been researched in various fields of white biotechnology, especially in biofuel production from lignocellulosic biomass. The commercial enzyme mixtures produced at industrial scales are not well characterized, and their proteinaceous components are poorly identified and quantified. The development of proteomic methods has made it possible to comprehensively overview the enzymes involved in lignocellulosic biomass degradation which are secreted under various environmental conditions. RESULTS: The protein composition of the secretome produced by industrial T. reesei (strain CL847) grown on a medium promoting the production of both cellulases and hemicellulases was explored using two-dimensional electrophoresis and MALDI-TOF or LC-MS/MS protein identification. A total of 22 protein species were identified. As expected, most of them are potentially involved in biomass degradation. The 2D map obtained was then used to compare the secretomes produced by CL847 and another efficient cellulolytic T. reesei strain, Rut-C30, the reference cellulase-overproducing strain using lactose as carbon source and inducer of cellulases. CONCLUSION: This study provides the most complete mapping of the proteins secreted by T. reesei to date. We report on the first use of proteomics to compare secretome composition between two cellulase-overproducing strains Rut-C30 and CL847 grown under similar conditions. Comparison of protein patterns in both strains highlighted many unexpected differences between cellulase cocktails. The results demonstrate that 2D electrophoresis is a promising tool for studying cellulase production profiles, whether for industrial characterization of an entire secretome or for a more fundamental study on cellulase expression at genome-wide scale

Obtention du cycle de vie complet d'Helix aperta Born de sites tunisiens en conditions contrôlées. Influence de la photopériode

International audienceCe travail montre que la croissance et la reproduction des escargots naticoïdes (Helix aperta, syn. Cantareus apertus) récoltés en fin d'été dans la région de Bazina (Tunisie) sont stimulées par les photopériodes de jours courts (JC = 8hL–16hO) et inhibées par celles de jours longs (JL = 18hL–6hO). Ainsi sous JC, à 20 ◦C, humidité de 80% et nourriture pour escargots : Helixal®, deux générations successives ont pu être obtenues en 10 mois, sans période réfractaire. Les effets de la photopériode sur la croissance sont réversibles et se manifestent après une période de latence de 4 à 8 semaines respectivement pour la stimulation par les JC et pour l'inhibition par les JL

Bioindication et unités (concentrations vs quantités): comparaison des cinétiques d'accumulation et d'élimination du Cd, Pb et Zn chez l'escargot Helix aspersa.

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Bioaccumulation, bioamplification des polluants dans la faune terrestre - Un outil pour la biosurveillance des écosystèmes

International audienceCet ouvrage est une revue des données sur la bioaccumulation des contaminants de l'environnement chez les invertébrés (nématodes, annélides, mollusques, arthropodes) et chez les vertébrés (reptiles, oiseaux, mammifères). L'intérêt de ces données pour l'évaluation du risque écologique, de même que divers modèles d'étude des transferts dans les chaînes trophiques et les relations entre bioaccumulation et effets toxiques sont présentés. Des recommandations pour une meilleure prise en compte de l'analyse de la bioaccumulation en évaluation des risques sont proposées

A full life-cycle bioassay with Cantareus aspersus shows reproductive effects of a glyphosate-based herbicide suggesting potential endocrine disruption

International audienceA full life-cycle (240 days) bioassay using the terrestrial snail, Cantareus aspersus, allowing exposureduring embryogenesis and/or the growth and reproduction phases, was used to assess the effects ofBypass®, a glyphosate-based herbicide (GlyBH), on a range of endpoints, including parameters underendocrine control. As a positive control, a mixture (R-A) made of diquat (Reglone®) and nonylphenols (NP, Agral®), known for its endocrine disrupting effects in other organisms, was tested. At environmental concentrations, both pesticides (R-A mixture and GlyBH) enhanced growth but reduced reproduction. The R-A mixture acted mainly on the fecundity through a delay in egg-laying of approximately 20 days and a strongly reduced number of clutches. This latter dysfunction may be caused by a permanent eversion of the penis, suggesting a disrupting effect at the neuro-endocrine level, which prevented normal mating. GlyBH acted on fertility, possibly due to a decrease in the fertilization of eggs laid by adults exposed during their embryonic development. These results, associated with the absence of observed effects on gonad histology of GlyBH exposed snails, suggested that the underlying mechanisms are neuro-endocrine

Trophic fate of inorganic and methyl-mercury in a macrophyte-macroinvertebrate food chain

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Trophic fate of inorganic and methyl-mercury in a macrophyte-chironomid food chain

Dietary transfer of mercury (Hg) is central for its effects on higher trophic animals, nonetheless, its driving parameters and characteristics are not well understood. Here we measured Hg species transfer (uptake) from the macrophyte Elodea nuttallii −mimicking tissues incorporation in sediments after decay- to Chironomus riparius. Methyl-Hg (MMHg) was more transferable than inorganic Hg (IHg) from plant’s intracellular and cell wall compartments. After 10-d-long exposure, MMHg was predominantly found in MMHg form in the cytosolic compartment (S) of chironomids, while IHg showed similar concentrations in S and insoluble debris (P) compartments. After cessation of Hg species exposure (depuration), only MMHg resulted in a bioaccumulation factor >1. Toxicokinetics modelling indicated a demethylation of MMHg in the S fraction and its concomitant storage in the P fraction as IHg during both uptake and depuration, revealing an elimination and detoxification mechanism. Our data support that MMHg is more transferable than IHg to sensitive subcellular targets as well as bioavailable fraction in chironomids, in line with field studies showing higher MMHg transfer than IHg in food webs. Hence our data point out macrophytes as a potential Hg source to benthic food webs to be considered for enhancing aquatic environment protection during phytoremediation programs

Basic dye adsorption onto modified chitosan: comparison and regression analysis of optimized isotherm models

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