Développement d'une plateforme électrochimique à base d'aptamère pour la biodétection de la dexaméthasone dans l'eau

La dexaméthasone (DXN) est une hormone glucocorticoïde synthétique utilisée principalement comme un agent anti-inflammatoire, anti-allergique et immunosuppresseur. Elle est largement utilisée comme agent stimulant la croissance et le développement musculaire dans les bétails et l'élevage des animaux. Cette hormone est rajoutée dans certains médicaments utilisés pour le dopage et l'amélioration de la performance sportive et le gain de poids. Malgré sa large utilisation, les caractéristiques de la dexaméthasone font d'elle un perturbateur endocrinien. Son interférence avec le système endocrinien peut entraîner des effets indésirables sur la reproduction, la croissance, le développement, le comportement et l'humeur. La présence de la dexaméthasone dans les eaux et les produits alimentaires avec des concentrations élevées nécessite un suivi et une surveillance précoces. La mise au point d'une méthode de détection simple, rapide, sensible et sélective pour cette hormone est d'une grande importance dans la recherche médicale, les analyses alimentaires et environnementales. Les biocapteurs constituent une alternative très intéressante par rapport aux autres instruments classiques de détection en raison de leur petite taille, leur facilité d'utilisation et leur faible coût. Ce sont des dispositifs analytiques conçus pour transformer un phénomène biochimique en un signal mesurable. Dans le but de pallier les limites des méthodes de détection existantes, nous présentons dans le cadre de ce mémoire de maîtrise un biocapteur impédimétrique à base d'aptamères pour la détection de la dexaméthasone dans les eaux. L'aptamère proposé a été développé en utilisant la sélection in vitro dans 19 cycles. L'aptamère proposé est le premier à être développé pour la détection de la dexaméthasone. Outre son faible coût de production et sa simplicité d'utilisation, l'aptacapteur développé offre une limite de détection très faible comparativement à la majorité des instruments analytiques existants. L'efficacité de cet aptacapteur est démontrée par une étude empirique sur différents échantillons d'eau contaminée par la dexaméthasone.\ud ______________________________________________________________________________ \ud MOTS-CLÉS DE L’AUTEUR : Biosenseurs, Dexaméthasone, Aptamères, Perturbateurs endocriniens, Biocapteurs impédimétriques, Aptacapteurs

UTILISATION D’INDICES POUR L’EVALUATION DE LA QUALITE DES SEDIMENTS : CAS DU BASSIN BOUMERZOUG (ALGERIE)

The objectives of this study are to use different indexes to assess the current pollution status in Boumerzoug basin. Indexes used in this study were Geo-accumulation Index (Igeo), Contamination Factor (CF), Contamination Degree (CD) and Sediment Pollution Index (SPI). Before, sediment trace metal concentrations (cadmium, chromium, copper, lead, nickel, zinc) have been investigated on surface sediments from permanent wadis of Boumerzoug basin in different seasons (winter, spring, summer and autumn). Trace metal concentrations followed the order: Zn>Pb>Cr>Cu>Ni>Cd. Indexes used give several status of sediment quality. Igeo, CF, CD and SPI reveal a polymetallic contamination dominated by two or more elements in which Cd, Cu and Pb are of greatest concern. Igeo gives more precision than CF, because it is classified into six classes. SPI has an advantage over the earlier indexes and viewed as a simple summary of the state of the sediment. However, the trace metal assessment indices are not to be used as the only indicator for sediment quality. More detailed analysis such as biological testing and analysis of existing benthic community related to sediment contamination should be performed for a better understanding about the nature, the fate and the toxic effects of contaminants in this ecosystem

An Overview of Cyanobacteria Harmful Algal Bloom (CyanoHAB) Issues in Freshwater Ecosystems

This chapter will present an overview of cyanobacterial harmful algal blooms (cyanoHABs) and biotic and abiotic factors, as well as various aspects associated with these worldwide ecological bursts. The exact causes of the cyanoHABs are still not well defined, but eutrophication and climate change (temperature increase, light intensity variation, etc.) are the two assumed main factors that may promote the proliferation and expansion of cyanobacterial blooms. However, these premises need to be profoundly investigated as the optimal combination of all factors such as increased nutrient loading, physiological characteristics of cyanobacterial species, and climate effects which could lead to the blooming pattern will require robust modeling approaches to predict the phenomena. Negative issues associated with cyanoHABs are diverse including the toxic products (cyanotoxins) released by certain taxa which can damage the health of humans and animal habitats around the related watershed as well as generate a huge water quality problem for aquatic industries

Teneurs Des Éléments Traces Métalliques Cu, Zn Et Pb Des Sédiments Du Barrage Béni Haroun (Nord-Est De l’Algérie)

This paper focuses on evaluating the degree of three metal pollution (Cu, Zn and Pb) in the sediments of Béni Haroun dam, located in northeastern of Algeria. For this reason, the superficial sediments were sampled at five stations, and the samples were taken at different seasons of the year. The results show low Cu and Zn levels which reflect natural conditions in relation to the area of geological nature. It also highlights the presence of Pb contamination (2.29 to 91.86µg/g). This result was also confirmed by various indices, including the geoaccumulation index (Igeo) and the contamination factor (FC). The Igeo values for Pb show moderate contamination of the Bge2 and Bge3 stations. CF values indicate moderate to considerable contamination for most stations by Pb. However, low or absent of Zn contamination was noted in all stations except for the Bge5. The correlation matrix and the PCA between all metal elements indicates that they were derived from similar sources. The contamination sources would probably establish a significant relationship between runoff and the erosion of agricultural lands. It is therefore an anthropogenic metal pollution related to agricultural activity using fertilizers and pesticides

Dynamique Des Eléments Nutritifs Et Du Phytoplancton Dans Le Barrage Béni Haroun Dans l’Est Algérien

In order to monitor the water quality of the Beni Haroun dam, used for the drinking water production, our research work aims to provide new scientific data on the phytoplankton population of the dam. This contribution is a qualitative and quantitative investigation of this important link in the ecosystem equilibrium. To our knowledge, this study has never been the subject of a previous one, despite many works already done on this dam. Water samples were collected monthly from January to December 2015 at five stations, spread over Beni Haroun dam. The exploitation of a database, relating to fourteen physicochemical and biotic variables, made it possible to determine: the spatiotemporal evolution of each variable, the correlations between variables, the annual variability of the algal biomass, the diversity and phytoplankton dominance

Atmospheric Aerosol Assisted Pulsed Plasma Polymerization: An Environmentally Friendly Technique for Tunable Catechol-Bearing Thin Films

In this work, an atmospheric aerosol assisted pulsed plasma process is reported as an environmentally friendly technique for the preparation of tunable catechol-bearing thin films under solvent and catalyst free conditions. The approach relies on the direct injection of dopamine acrylamide dissolved in 2-hydroxyethylmethacrylate as comonomer into the plasma zone. By adjusting the pulsing of the electrical discharge, the reactive plasma process can be alternatively switch ON (tON) and OFF (tOFF) during different periods of time, thus allowing a facile and fine tuning of the catechol density, morphology and deposition rate of the coating. An optimal tON/tOFF ratio is established, that permits maximizing the catechol content in the deposited film. Finally, a diagram, based on the average energy input into the process, is proposed allowing for easy custom synthesis of layers with specific chemical and physical properties, thus highlighting the utility of the developed dry plasma route

Changes in protein expression in mussels Mytilus galloprovincialis dietarily exposed to PVP/PEI coated silver nanoparticles at different seasons

Potential toxic effects of Ag NPs ingested through the food web and depending on the season have not been addressed in marine bivalves. This work aimed to assess differences in protein expression in the digestive gland of female mussels after dietary exposure to Ag NPs in autumn and spring. Mussels were fed daily with microalgae previously exposed for 24 hours to 10 µg/L of PVP/PEI coated 5 nm Ag NPs. After 21 days, mussels significantly accumulated Ag in both seasons and Ag NPs were found within digestive gland cells and gills. Two-dimensional electrophoresis distinguished 104 differentially expressed protein spots in autumn and 142 in spring. Among them, chitinase like protein-3, partial and glyceraldehyde-3-phosphate dehydrogenase, that are involved in amino sugar and nucleotide sugar metabolism, carbon metabolism, glycolysis/gluconeogenesis and the biosynthesis of amino acids KEGG pathways, were overexpressed in autumn but underexpressed in spring. In autumn, pyruvate metabolism, citrate cycle, cysteine and methionine metabolism and glyoxylate and dicarboxylate metabolism were altered, while in spring, proteins related to the formation of phagosomes and hydrogen peroxide metabolism were differentially expressed. Overall, protein expression signatures depended on season and Ag NPs exposure, suggesting that season significantly influences responses of mussels to NP exposure.This work has been funded by the Spanish Ministry of Economy and Competitiveness (NanoSilverOmics project MAT2012-39372), Basque Government (SAIOTEK project S-PE13UN142 and Consolidated Research Group GIC IT810-13) and the University of the Basque Country UPV/EHU (UFI 11/37 and PhD fellowship to N.D.). This study had also the support of Fundação para a Ciência e Tecnologia (FCT) from Portugal through the Strategic Project UID/MAH00350/2013 granted to CIMA. The contribution of K. Mehennaoui was possible within the project NanoGAM (AFR-PhD-9229040) and M. Mikolaczyk was supported by a PhD fellowship from the French Ministry of Higher Education and Research.info:eu-repo/semantics/acceptedVersio

Compréhension de l'impact des nanoparticules manufacturées : intérêt du gammare comme modèle invertébrés ?

The potential toxicity of nanomaterials is of high societal and scientific interest due to the promise of ground-breaking innovations for many technical applications. However, toxicity can often not be related to the actual size, mass or surface area of the single nanoparticles (NPs) or the NP agglomerates. Therefore, it can be proposed that the toxicity is greatly influenced by other inherent and non-understood properties of the particles to which ions dissolving from the particle, surface or molecules adhering to the surface interfering with the uptake of NPs into cells, may have important contributions. The PhD project “NANOGAM”, closely linked up to CORE2012 NANION project that aims to obtain knowledge to understand some of the processes and factors involved in NP uptake and toxicity as such understanding is a prerequisite for the development of nanomaterials following the safer-by-design philosophy. This PhD project aims to investigate, based on known characteristics of the key physico-chemical parameters; as size and surface functionalities, of a well-chosen list of silver and gold NPs, the uptake, and dependent biological effects of different complexity (mortality, behavioural effects, physiological effects, transcriptomic effects, etc.), on a sensitive species; Gammarus fossarum (Crustacea Amphipoda), in order to understand to which extent toxicity of nanomaterials is due to intrinsic material properties or ion leaching. Such understanding will contribute to the prediction of toxicity based on material properties rather than repetitive testing of an indefinite number of new nanomaterials. G. fossarum were exposed at low concentrations of AgNPs and AuNPs for 72h or 15 days in presence or absence of food. The obtained results showed that (i) surface coating is the main factor governing AgNPs and AuNPs uptake by G. fossarum, (ii) both released ions and NPs themselves play a role in the potency of the studied AgNPs and AuNPs and (iii) chemical composition led to different effects at the sub-individual levels (target genes expression) and different tissue distribution as AgNPs were found in G. fossarum gills while AuNPs were found in the intestinal caeca. Additionally, this work shows that Gammarus sp. are valuable models for the study of the effects of AgNPs and AuNPsLa toxicité potentielle des nanomatériaux présente un intérêt sociétal et scientifique élevé en raison de la promesse d'innovations pour de nombreuses applications techniques. Cependant, elle n’est pas forcément liée à la taille réelle, à la masse, à la surface des nanoparticules (NP) ou à leurs agglomérats. La toxicité des NPs pourrait être fortement influencée par d'autres propriétés inhérentes et encore incomprises telles que le relargage d’ions, de la particule elle-même, sa surface, ou des molécules adhérentes à la surface, qui interfèreraient avec l'absorption cellulaires des NPs. Le projet « NANOGAM» étroitement lié au projet « FNR CORE2012 NANION », vise à définir certains processus et facteurs impliqués dans l'absorption des NPs et leur toxicité. Une telle compréhension est une condition préalable au développement des nanomatériaux, fondement de la philosophie « safer-by-design ». Les objectifs de ce projet de thèse sont multiples. En tenant compte des caractéristiques des principaux paramètres physico-chimiques tels que la taille et l’aspect de la surface, l’étude a porté sur l'absorption de NPs d'argent et d'or, et leurs effets biologiques via une approche multi-biomarqueurs (mortalité, effets comportementaux, effets physiologiques, effets transcriptomiques, etc.) sur une espèce sensible, Gammarus fossarum (Crustacea Amphipoda). Le but de cette investigation est de comprendre si la toxicité des nanomatériaux est inhérente aux propriétés intrinsèques des NPs ou plutôt aux ions relargués, ce qui contribuera à la prédiction de la toxicité des NPs en rapport avec leurs propriétés physico-chimiques et ce afin de limiter le nombre d’essais répétitifs sur de nouveaux nanomatériaux. G. fossarum ont été exposés à de faibles concentrations d'AgNPs et AuNPs pendant 72h à jeun et 15 jours nourris. Les résultats obtenus ont montré que (i) la nature de l’enrobage de surface est le principal facteur responsable de l'absorption d'AgNPs et d'AuNPs par G. fossarum ; (ii) les ions libérés et les NPs elles-mêmes jouent un rôle dans la toxicité des AgNPs et AuNPs étudiées ; (iii) la composition chimique des NPs a conduit à des effets différents aux niveaux sub-individuels (transcriptomique), ainsi qu’à une distribution différente dans les tissues selon la nature métallique de la NP. Les AgNPs ont été localisées dans les branchies de G. fossarum tandis que les AuNPs ont été observées dans les caeca intestinaux. Cette étude a également révélé que Gammarus sp. est un excellent modèle pour l'étude de la toxicité et des effets des AgNPs et des AuNP

Surveillance biologique du saturnisme subclinique chez les bovins : etude du poil en tant qu'indicateur d'exposition

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc