Locomotion behavior of juveniles of the freshwater pearl mussel Margaritifera margaritifera: A new non-invasive tool for the evaluation of stress effects

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Evaluation des effets écotoxiques des rejets de STEP sur embryons de truite fario (Salmo trutta fario) encagés in situ

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Experimental ingestion of fluorescent microplastics by pacific oysters, Crassostrea gigas, and their effects on the behaviour and development at early stages

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An environmentally realistic pesticide and copper mixture impacts embryonic development and DNA integrity of the Pacific oyster, Crassostrea gigas

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Sub-lethal effects of waterborne copper in early developmental stages of rainbow trout (Oncorhynchus mykiss)

International audienceThe aim of this work was to study the impact of copper during a sub-chronic exposure to environmental concentrations in the early life stages of rainbow trout (Oncorhynchus mykiss). Eyed-stage embryos of rainbow trout, at 265°D, were exposed in semi-static conditions to sublethal concentrations of CuSO4 up to the larval stage (528 °D) under laboratory-controlled conditions. During 3 weeks, they were exposed to the environmentally-realistic concentration of 2 µg/L Cu and to a 10-fold higher concentration, 20 µg/L Cu. Several biological (survival, hatching success, malformation, growth) and behavioral (swimming activity) and molecular endpoints (genotoxicity and gene transcription) were studied. Exposure to 20 µg/L Cu had an inhibitory effect on hatching and increased half-hatched embryos (25%). At the end of the exposure, no significant differences were observed in growth of the larvae exposed to the highest Cu concentration. However, larvae exposed to 2 µg/L Cu exhibited increased growth in comparison with non-exposed larvae. The percentage of malformed larvae was significantly higher for both copper conditions, with skeletal malformations being the most observed. Expression of several genes was evaluated in whole larvae using quantitative real-time PCR. Genes involved in detoxification (gst, mt1 and mt2) and in cell cycle arrest (p53) were significantly repressed in both copper conditions when compared to control. In addition, potential genotoxic effects on larvae were investigated by the comet assay on blood cells, but this test did not demonstrate any significant DNA damage on larvae exposed to copper. This study confirms the adverse effects of copper on early life stages of rainbow trout even at the lowest environmentally relevant tested concentration

An environmentally realistic pesticide and copper mixture impacts embryonic development and DNA integrity of the Pacific oyster, Crassostrea gigas

International audienceFrequent occurrences of pesticides in the environment have raised concerns that combined exposure to these chemicals may result in enhanced toxicity through additive or synergistic interaction between compounds. Spermatozoa and embryos of the Pacific oyster, Crassostrea gigas, were exposed to different concentrations of a pesticide mixture with and without copper, mimicking the cocktail of pollutants occurring in the oyster culture area of Arcachon Bay. For the 1× exposure condition, measured concentration corresponds to a total concentration of 1.083 μg L−1 for the mixture of 14 pesticides and to 6.330 μg L−1 for copper (Cu). Several endpoints including larval abnormalities, DNA damage to spermatozoa and embryo and gene expression in D-larvae were investigated. Results demonstrated that pesticide mixtures in combination with or without copper induced a dose-dependent increase in embryotoxic and genotoxic effects on D-larvae from the lowest tested dose of 0.1×. Transcription of genes involved in anti-oxidative stress (cat), respiratory chain (coxI), metal detoxification (mt1 and mt2), and cell cycle arrest and apoptosis (p53) was found to be significantly downregulated while the xenobiotic biotransformation gene gst was significantly upregulated in embryos exposed to pesticide mixture with and without Cu. These findings raise the question of the possible impacts of mixtures of pesticides and metals on wild or farmed oyster populations from polluted coastal marine areas

Psychotropic drugs in mixture alter swimming behaviour of Japanese medaka (Oryzias latipes) larvae above environmental concentrations

International audiencePsychiatric pharmaceuticals, such as anxiolytics, sedatives, hypnotics and antidepressors, are among the most prescribed active substances in the world. The occurrence of these compounds in the environment, as well as the adverse effects they can have on non-target organisms, justifies the growing concern about these emerging environmental pollutants. This study aims to analyse the effects of six psychotropic drugs, valproate, cyamemazine, citalopram, sertraline, fluoxetine and oxazepam, on the survival and locomotion of Japanese medaka Oryzias latipes larvae. Newly hatched Japanese medaka were exposed to individual compounds for 72 h, at concentrations ranging from 10 μg L−1 to 10 mg L−1. Lethal concentrations 50 % (LC50) were estimated at 840, 841 and 9,136 μg L−1 for fluoxetine, sertraline and citalopram, respectively, while other compounds did not induce any significant increase in mortality. Analysis of the swimming behaviour of larvae, including total distance moved, mobility and location, provided an estimated lowest observed effect concentration (LOEC) of 10 μg L−1 for citalopram and oxazepam, 12.2 μg L−1 for cyamemazine, 100 μg L−1 for fluoxetine, 1,000 μg L−1 for sertraline and >10,000 μg L−1 for valproate. Realistic environmental mixture of the six psychotropic compounds induced disruption of larval locomotor behaviour at concentrations about 10- to 100-fold greater than environmental concentrations

Response of zebrafish and Japanese medaka to imidacloprid: a comparative study

International audienceNeonicotinoids are among the most produced and used insecticides and are frequently found in freshwater with concentrations ranging from ng to μg/L. These molecules are small and very soluble in water. This given, they are likely to pass the chorion and thus easily enter embryos of fish. It is known that these compounds impact on insects, including bees, in terms of toxicity and behaviour, but whether similar impacts could be observed in fish is not yet known. The aim of this study was to investigate effects of exposure to imidacloprid, one of the most used neonicotinoids, on the development and behaviour of two common fish lab species: Zebrafish (Danio rerio) and Japanese medaka (Oryzias latipes). Fish were exposed during 5 (zebrafish) and 13 days (medaka) to 0, 0.2, 2, 20, 200 and 2000 μg/L imidacloprid by aqueous exposure, matching the respective time from fertilization to emerged larvae for the two species. At similar developmental stages, survival, hatch, growth, morphology, behaviour and histology were examined. No impact on survival was found. A delay for 2 μg/L imidacloprid exposures was observed for hatch in both species. Except for the 20 mg/L exposure level, imidacloprid led to hypoactivity in both species. A striking difference was found in morphology: a high number of deformities were noticed for medaka whereas almost none were found in zebrafish. Yolk and bone oedemas started to be noticed at 20 μg/L after hatch, jaw deformity and lordosis/scoliosis increased with concentration level. An increase of haemorrhage was found at the highest concentration (2000 μg/L). In order to shed light on the observed species differences, we intend to investigate the uptake of imidacloprid into the fish embryos and its biotransformation

Existe-t-il un transfert trophique des MP et quels sont les effets toxiques chez les larves et les juvéniles de soles ?

International audienceIntroduction En raison d’une forte pression anthropique, les zones estuariennes sont touchées par une importante pollution aux microplastiques (MP) et les espèces inféodées à ces zones y sont particulièrement exposées. L’objectif de cette étude, financée par le programme Seine-Aval, est d’évaluer les effets de MP environnementaux collectés en estuaire de Seine sur une espèce emblématique de nos côtes, la sole commune (Solea solea) à travers une exposition directe ou par voie trophique. Exposition Deux types d’expositions ont été réalisés. La première est une exposition directe de larves de sole à plusieurs plastiques industriels de différentes tailles et densités (27-35 μm et d=0.99 ; 27-32 μm et d=1.20 ; 63-75 μm et d=1.20) ainsi qu’à un cocktail d'échantillons environnementaux prélevés dans l’estuaire de la Seine (100 μm) afin de déterminer la cinétique d'ingestion et d'égestion. Pour mettre en évidence d'éventuelles différences en fonction du stade de développement, cette exposition a été réalisée avant (7 jours post éclosion, jpe), pendant (21-22 jpe) et après la métamorphose (41-42 jpe). Dans une seconde expérience, des juvéniles de sole ont été nourris avec des vers estuariens (Hediste diversicolor) préalablement exposés au MP via le sédiment. Comme précédemment les MP utilisés sont d’origines industrielles ou d'estuaire de Seine. Plusieurs marqueurs d’état de santé tels que la survie, la croissance, le comportement, le métabolisme énergétique, le système immunitaire, le système digestif ont été étudiés. Résultats Quelque soit le stade de développement, les larves ont ingérés tous les plastiques indépendamment de la taille et/ou du type et aucune différence de cinétique d'ingestion ou d'égestion n'a été mise en évidence. Pendant la métamorphose le comportement natatoire des larves de sole a été modifié : la distance parcourue est plus faible chez les larves ayant consommé des MP et pour tous les MP testés. Chez les juvéniles de soles nourris avec des vers exposés à des MP environnementaux (400 μm) ou industriels (100-250 μm) nous avons mis en évidence une modification de comportement dans le choix du sol proposé (noir ou blanc) et de couleur des individus exposés pour la concentration la plus haute et les MP enrobés de Benzo(a)Pyrène ou d’Oxybenzone. Ces observations sont indicatrices d'un stress physiologiques. Ces premiers résultats mettent en évidence les effets délétères des microplastiques lors d'expositions directes ou indirectes à différents stades de vie. Ce travail sera complété par une exposition de larves de soles pendant 1 mois à partir de l'éclosion à des copépodes (Acartia tonsa) ayant eux-mêmes été exposés à des MP