15 research outputs found
Ătudes de biomarqueurs chez la mye commune (Mya arenaria) du fjord du Saguenay : bilan de recherches (1997 Ă 2006)
Cet Ă©crit se veut une synthĂšse des principales trouvailles affĂ©rentes aux Ă©tudes de terrain conduites annuellement de 1997 Ă 2006 en zones intertidales du fjord du Saguenay, et de celles situĂ©es autour de sa confluence avec lâestuaire du Saint-Laurent, dans le but de mieux comprendre les stress anthropiques auxquels est soumise la mye commune (Mya arenaria), bivalve ubiquiste de ces habitats sĂ©dimentaires. Ă lâaide dâune batterie variĂ©e de biomarqueurs, lesquels ont fait lâobjet de mesures chez lâanimal entier, certains de ses tissus ou cellules, nous avons pu mettre en Ă©vidence divers effets Ă©cotoxiques qui sont vraisemblablement imputables aux sources (urbaines, industrielles, portuaires, diffuses ou atmosphĂ©riques) de contamination chimique impactant le Saguenay. DĂ©pendant du site et de ses caractĂ©ristiques pollutionnelles, nous avons notĂ© des dĂ©rĂšglements de santĂ© chez la mye qui incluent des effets sur son systĂšme reproducteur (divers types de perturbation endocrine associĂ©s aux substances estrogĂ©niques, aux mĂ©taux ou aux TBT), sur son systĂšme immunitaire (stimulation ou dĂ©pression dâimmunocompĂ©tence jaugĂ©e par la capacitĂ© de phagocytose dâhĂ©mocytes), ainsi que des effets cumulatifs de polluants qui se traduisent par des rĂ©ponses, Ă la hausse ou Ă la baisse, de biomarqueurs de dĂ©fenses (e.g., mĂ©tallothionĂ©ines, CYP1A1, glutathione S-transfĂ©rases), de dommages (e.g., augmentation de brins dâADN, augmentation de lâactivitĂ© de cyclo-oxygĂ©nase tĂ©moignant dâinflammation, peroxydation des lipides) et morphologiques (e.g., inhibition de croissance, baisse dâindice gonado-somatique). Nous dĂ©montrons aussi une plus grande dĂ©pense en Ă©nergie au niveau mitochondrial (transport dâĂ©lectrons mitochondrial dans la gonade ou glande digestive) chez les myes de zones impactĂ©es, laquelle semble pouvoir ĂȘtre exacerbĂ©e en conditions de stress thermiques que laissent prĂ©sager les changements climatiques Ă venir. Au final, ce bilan dâĂ©tudes de biomarqueurs confirme lâutilitĂ© du modĂšle bivalve Mya arenaria comme bio-indicateur de la qualitĂ© hydrique du Saguenay et il renseigne sur les divers affronts que subissent ces invertĂ©brĂ©s dans ce milieu toujours aux prises avec des sources de contamination variĂ©es. Dâautres Ă©tudes envisagĂ©es affineront nos connaissances au sujet des risques cumulatifs liĂ©s Ă la contamination chimique du fjord.This paper presents the major findings of annual field outings conducted from 1997 to 2006 in Saguenay Fjord intertidal areas as well as those located in proximity with the St. Lawrence River estuary. Study objectives sought to enhance our understanding of pollution pressures incurred on the soft shell clam, Mya arenaria, endemic to mud flats of these regions. By measuring the responses of a battery of biomarkers in whole animals, organs or cells, we demonstrated various adverse effects that are likely linked to chemical contamination sources (municipal, industrial, portuary, non point and atmospheric) intrinsic to the Saguenay area. Based on site and pollution features proper to each, health problems were observed in clams that included effects on their reproductive system (endocrine disruption events linked to estrogenic substances, metals or TBT), on their immune system (increase or decrease of immunocompetence assessed by phagocytic performance of hemocytes), as well as cumulative effects of pollutants, shown either by upward or downward responses of defense biomarkers ((e.g., metallothioneins, CYP1A1, glutathion Sâtransferase), damage biomarkers (e.g., increase in DNA strand breaks, increase in inflammatory cyclo-oxygenase activity, lipid peroxidation) and metrics biomarkers (e.g., growth inhibition, lower gonado-somatic index). In pollution-impacted sites, clams further displayed a greater expenditure of mitochondrial energy (measured by mitochondrial electron transport in gonad or digestive gland), an energy loss that could possibly be augmented under thermic stress conditions linked to climate change. This long-term biomarker work establishes Mya arenaria as a useful bioindicator species to appraise Saguenay Fjord water quality as reflected by the diverse chemical insults to which these invertebrates are exposed in an ecosystem still struggling with multiple contamination inputs. Future studies should contribute to strengthen our knowledge related to cumulative risk issues linked to the fjordâs chemical pollution
Quâen est-il de lâĂ©tat de santĂ© des myes au Saguenay ? Un bilan dâĂ©tudes sur plus dâune dĂ©cennie
Le fjord du Saguenay, reconnu pour sa faune diversifiĂ©e mais aussi pour la contamination reliĂ©e aux activitĂ©s industrielles et anthropiques, a fait lâobjet dâun vaste programme de suivi environnemental, entrepris par notre Ă©quipe et qui visait Ă rĂ©pondre Ă la question fondamentale : LâĂ©tat de santĂ© des myes sâest-il modifiĂ© dans le fjord du Saguenay ? Dans cet article de synthĂšse, nous avons regroupĂ© des rĂ©sultats dĂ©jĂ publiĂ©s sur la condition physiologique de Mya arenaria ainsi que des rĂ©sultats originaux pour extraire des tendances, de façon Ă rĂ©pertorier les sites qui sâavĂšrent critiques pour le bien-ĂȘtre physiologique de la mye. Mya arenaria (LINNĂ, 1758) ou mye des sables, choisie comme espĂšce sentinelle, a Ă©tĂ© Ă©chantillonnĂ©e de 1994 Ă 2007, en pĂ©riode de maturitĂ© sexuelle, dans des sites situĂ©s Ă lâintĂ©rieur du fjord et Ă son embouchure. Les objectifs de cet article sont de comparer les rĂ©sultats de diffĂ©rents indices de condition et de suivis hormonaux et de la gamĂ©togenĂšse de chaque site et en fonction des sexes, pour identifier les sites moins favorables pour la croissance et la reproduction de la mye. Nous avons dĂ©montrĂ© que les myes de BaieâSainte-Catherine subissent des retards de gamĂ©togenĂšse tandis que les niveaux dâhormones stĂ©roĂŻdiennes sont trĂšs bas Ă Tadoussac. Ces deux sites sont soumis Ă des influences portuaires et Ă la circulation navale. Le site de BaieâĂternitĂ©, plus en amont, se caractĂ©rise par des influences portuaires (huiles et peintures antisalissures) et une forte contamination mĂ©tallique de sources urbaines et terrigĂšnes. AnseâauxâĂrables est un site prĂšs des influences industrielles, tandis que AnseâSaintâJean est fortement influencĂ©e par les effluents municipaux et domestiques. Dâamont en aval sur la riviĂšre Saguenay, les myes des sites AnseâĂ âlaâCroix, AnseâauxâĂrables, PetitâSaguenay, AnseâĂ âlaâBarque, Tadoussac et PointeâauxâAlouettes ont montrĂ© une croissance moindre. Les sites de BaieâĂternitĂ©, AnseâauxâĂrables, AnseâSaintâJean et Baie-Sainte-Catherine ont un indice de maturitĂ© sexuelle moindre quâaux autres sites, les donnĂ©es regroupĂ©es dĂ©montrant que ce sont les sites les plus influencĂ©s dans le fjord du Saguenay, rĂ©sultats corroborĂ©s par les rĂ©sultats de phagocytose. Toutes ces donnĂ©es dĂ©montrent que lâĂ©tat physiologique de la mye rĂ©pond Ă diffĂ©rents facteurs, anthropiques, biotiques et abiotiques, et que les sources ponctuelles de contamination viennent renforcer les effets nĂ©gatifs de paramĂštres abiotiques telles la tempĂ©rature et les conditions trophiques.The Saguenay fjord has been submitted for many years to anthropogenic influences. We surveyed this ecosystem between 1994 and 2007 to assess if Mya arenaria health status was altered by the contamination present in this ecosystem. The physiological condition of clams was determined using grouped annual data from sites at the mouth and in the Saguenay fjord. The results were analyzed according to sex and sites for all the samplings done during the active gametogenesis. The aims of this paper are to compare results of condition signs, gametogenesis stages and hormonal levels between sites and according to sex, to finally identify which sites were less favorable for the growth and reproduction of clams. We have shown that clams from Baie-Sainte-Catherine had delayed gametogenesis while those from Tadoussac showed very low steroid hormonal levels. Portuary and naval circulation influences could explain these particular results that also correspond to those from phagocytosis. Upstream in BaieâĂternitĂ©, portuary influences (oils, anti-fouling paints) and metallic inputs from urban and terrigenous sources were reported. In Anse-aux-Ărables, metallic contamination comes from industrial sources, while Anse-SaintâJean is influenced by sewage discharges from domestic and urban origin. From upstream to downstream, clams from AnseâĂ âlaâCroix, AnseâauxâĂrables, PetitâSaguenay, AnseâĂ âlaâBarque, Tadoussac and PointeâauxâAlouettes showed decreased growth. BaieâĂternitĂ©, AnseâauxâĂrables, AnseâSaintâJean and Baie-Sainte-Catherine sites, with their lower sexual maturity index and decreased phagocytosis, were shown to be the more influenced by contamination. All these data show that physiological condition of Mya arenaria reflects the combined effects of abiotic factors such as contamination, trophic conditions and site characteristics
Oxidative stress and immunologic responses following a dietary exposure to PAHs in Mya arenaria
<p>Abstract</p> <p>Background</p> <p>The aim of this research was to investigate oxidative stress and immune responses following a dietary polycyclic aromatic hydrocarbon (PAH) exposure in a marine bioindicator organism, the soft shell clam, <it>Mya arenaria</it>. Immune parameters in hemolymph (haemocyte number, efficiency of phagocytosis and haemocyte activity) and assessment of oxidative stress using catalase (CAT) activity and levels of malondialdehyde (MDA) performed on the digestive gland were estimated as biomarkers in clams fed in mesocosm with PAH contaminated phytoplankton. MDA levels and CAT activities were also measured <it>in situ </it>in organisms sampled in a control site (Metis Beach, Québec, Canada) as well as organisms sampled in a site receiving domestic effluents (Pointe-au-PÚre, Québec, Canada), to assess effects of abiotic variables related to seasonal variations and mixed contamination on the selected parameters.</p> <p>Results</p> <p>Results on immune parameters suggest that the PAHs may interfere with the maturation and/or differentiation processes of haemocytes. MDA results showed that lipid peroxidation did not occur following the exposure. The levels of CAT activity corresponded to weak antioxidant activity (no significant differences). Recovery was noted for all the immune endpoints at the end of the experiment.</p> <p>Conclusion</p> <p>Results suggest that immune parameters are early biomarkers that can efficiently detect a physiological change during a short term exposure to low concentrations of PAHs. The <it>in situ </it>survey (in the natural environment) suggested that clams from the Pointe-au-PÚre site did not show any oxidative stress as well as the clams contaminated in mesocosm, probably due to the low concentrations of PAHs used for this study. MDA levels increased however in organisms from Metis Beach, a response probably related to domestic effluents or parasitism.</p
Exemple de coopĂ©ration franco-quĂ©bĂ©coises : la rĂ©alisation dâun cours sur la pollution marine dans le cadre de lâagence universitaire francophone
Un cours virtuel (http://www3.uqar. uquebec.ca/jpellerin/seme/) a Ă©tĂ© conçu pour les francophones du monde entier et proposĂ© avec diffĂ©rents cheminements pour des formations spĂ©cialisĂ©es ou finalisĂ©es. Le cours est composĂ© de 20 modules couvrant les notions indispensables pour la comprĂ©hension de lâenvironnement marin, de la pollution marine et des outils de biosurveillance. Les chercheurs impliquĂ©s dans cette rĂ©alisation provenaient du QuĂ©bec (J. Pellerin), de France (J.-C. Amiard), de Tunisie (P. AĂŻssa) et de Mauritanie (Z. Sidoumou). Nous avons profitĂ© de lâexpĂ©rience de chacune des Ă©quipes en environnement (enseignement et recherche) pour concevoir des modules qui, par leurs exemples, mises en situation et Ă©tudes de cas, sâadaptent aux Ă©tudiants provenant de diffĂ©rentes cultures et subissant des problĂšmes environnementaux diffĂ©rents selon que leur pays soit en zone tempĂ©rĂ©e, subtropicale ou tropicale.Pellerin Jocelyne. Exemple de coopĂ©ration franco-quĂ©bĂ©coises : la rĂ©alisation dâun cours sur la pollution marine dans le cadre de lâagence universitaire francophone. In: Ăchanges scientifiques et techniques dâune rive atlantique Ă lâautre. Actes du 133e CongrĂšs national des sociĂ©tĂ©s historiques et scientifiques, « Migrations, transferts et Ă©changes de part et dâautre de lâAtlantique », QuĂ©bec, 2008. Paris : Editions du CTHS, 2009. pp. 167-172. (Actes des congrĂšs nationaux des sociĂ©tĂ©s historiques et scientifiques, 133-1
ActivitĂ© vitellogĂ©nique et stĂ©roĂŻdienne chez Mya arenaria (mollusque bivalve) durant la gamĂ©togenĂšse et en rĂ©ponse Ă une exposition au 17Ă-oestradiol
Mya arenaria est un bivalve marin endobenthique et ubiquiste. Les connaissances Ă©cophysiologiques sur les changements biochimiques relatifs Ă la gamĂ©togenĂšse et l'implication des hormones stĂ©roĂŻdiennes dans le contrĂŽle hormonal de cette derniĂšre sont encore limitĂ©es chez cette espĂšce. Cette thĂšse de doctorat rapporte de nouvelles connaissances sur le processus vitellogĂ©nique et la prĂ©sence d'hormones stĂ©roĂŻdiennes (testostĂ©rone et 17Ă-Ćstradiol) dans la gonade des myes durant la gamĂ©togenĂšse. L'accroissement du diamĂštre des ovocytes a permis de dĂ©finir une sĂ©quence vitellogĂ©nique durant laquelle l'augmentation des concentrations en ADN et en ARN est significative et l'augmentation de la quantitĂ© de protĂ©ines de rĂ©serve (>400 kDa) est Ă©galement effective. Les hormones stĂ©roĂŻdiennes apparaissent impliquĂ©es dans le contrĂŽle hormonal de la gamĂ©togenĂšse bien que leurs concentrations soient comparables chez les deux sexes et que leurs interactions avec les neurohormones restent Ă dĂ©finir.NANTES-BU MĂ©decine pharmacie (441092101) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF
Multiple experimental approaches of immunotoxic effects of mercury chloride in the blue mussel, Mytilus edulis, through in vivo, in tubo and in vitro exposures
International audienceBiological impairments due to mercury discharge into the environment are now an issue of global concern. From the three forms of mercury found in aquatic ecosystems, the immunotoxic effects of mercury chloride were examined in the model animal, the blue mussel. In order to investigate the toxic potency of this chemical, three exposure regimes were carried out: chronic exposure of groups of individuals, a new protocol "in tubo" designed for sub-acute exposures of individuals, and acute exposures of target cells. Chronic exposure revealed significant immunotoxic effects after 7 days at 10â6 M, while acute exposures showed significant inhibition of phagocytosis at 10â4 M and 10â3 M. In sub-acute exposures both circulating haemocytes and haemocyte mortality increased at 10â4 M and 10â3 M while phagocytosis and the clearance rate drew hormetic toxic effects on healthy individuals. These results suggest the use of the "in tubo" design for bivalve toxicological individual studies
Relative potency of PCB126 to TCDD for sublethal embryotoxicity in the mummichog (Fundulus heteroclitus)
International audienceThe relative potency (ReP) of 3,3',4,4',5-pentachlorobiphenyl (PCB126) to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) for sublethal responses was assessed in Fundulus heteroclitus embryos. Eggs were treated with intravitelline injections of graded sublethal doses of PCB126 (312-5000 pg g(-1) wet weight, ww) or TCDD (5-1280 pg g(-1) ww). At 16 days post-fertilization (DPF), craniofacial deformities were observed in larvae hatched from eggs treated with the two highest doses of PCB126 (2500-5000 pg g(-1) ww). Both compounds caused a dose-responsive reduction of larval growth and prey capture ability (at â„1250 pg g(-1) ww), and induction of ethoxyresorufin-O-deethylase (EROD) activity (at â„80 pg g(-1) ww). The dose-response relationships for EROD activity for PCB126 and TCDD had similar slopes and the ReP of PCB126 to TCDD for EROD activity was estimated at 0.71. This is 140-fold higher than the World Health Organization (WHO) TCDD equivalency factor (TEF) of PCB126 for fish (0.005), which is based on rainbow trout (Oncorhynchus mykiss) embryolethality data. The slope of the dose-response relationship for prey capture ability for PCB126 was steeper than for TCDD, suggesting different mechanisms of action. Expression levels of several genes were also studied by quantitative real-time polymerase chain reaction (qPCR) following exposure to single doses of TCDD or PCB126 (1280 and 1250 pg g(-1) ww, respectively) causing similar EROD induction. A different pattern of responses was observed between PCB126 and TCDD: PCB126 appeared to induce antioxidant responses by inducing sod2 expression, while TCDD did not. These results suggest that relative potencies are species-specific and that the current ReP for PCB126 underestimates its toxicity for some fish species. It is recommended to develop species-specific RePs for a variety of sublethal endpoints and at environmentally relevant doses
Physiological effects of temperature and a herbicide mixture on the soft-shell clam Mya arenaria (Mollusca, Bivalvia)
The aim of the current study was to investigate effects of temperature and a mixture of herbicides on the physiological status of the bivalve Mya arenaria. Bivalves acclimated to two temperatures (7 and 18°C) were exposed for 28âd to 0.01âmg/L of a pesticide formulation containing dichlorophenoxyacetic acid (2,4âD), 2â(2âmethylâ4âchlorophenoxy) propionic acid (mecoprop), and 3,6âdichloroâ2âmethoxybenzoic acid (dicamba). At days 7, 14, and 28, mortality, immune parameters (hemocyte number, phagocytic activity, and efficiency), biomarkers of oxidative stress (catalase [CAT] and superoxide dismutase [SOD] activities and malondialdehyde [MDA] content), the metabolic enzyme cytochrome C oxidase (CCO), a biomarker of pesticide exposure (acetylcholinesterase [AChE]), and the activity of an enzyme related to gametogenesis (aspartate transcarbamylase [ATCase]) were monitored in clam tissues. Gonadosomatic index (GSI), condition factor (CF), and sex were also assessed. In clams acclimated to 7°C, exposure to pesticide enhanced CCO activity and CF and decreased MDA content, hemocyte number, CAT, and SOD activities. In clams kept at 18°C, pesticide effects appeared minor compared with samples kept at 7°C. In bivalves acclimated to 18°C, CCO, SOD, and ATCase activity and MDA content were enhanced, and hemocyte number, CAT, and AchE activities and phagocytosis were suppressed. In samples exposed to pesticides, increased temperature enhanced MDA content and CCO and SOD activity and suppressed hemocyte number and CAT and AchE activity. A gradual sexual maturation was observed in both sexes through experimental time, but females had a higher sensitivity to temperature and pesticides compared to males. Increased temperature altered the ability of the sentinel species Mya arenaria to respond to pesticide exposures. Further work is needed to understand the impacts of increasing temperature on the whole St. Lawrence estuary ecosystem
Sequence analysis of a normalized cDNA library of Mytilus edulis hemocytes exposed to Vibrio splendidus LGP32 strain
In the past decades, reports on bivalves' pathogens and associated mortalities have steadily increased. To face pathogenic micro-organisms, bivalves rely on innate defenses established in hemocytes which are essentially based on phagocytosis and cytotoxic reactions. As a step towards a better understanding of the molecular mechanisms involved in the mussel Mytilus edulis innate immune system, we constructed and sequenced a normalized cDNA library specific to M. edulis hemocytes unchallenged (control) and challenged with Vibrio splendidus LGP32 strain for 2, 4 and 6âh. A total of 1,024,708 nucleotide reads have been generated using 454 pyrosequencing. These reads have been assembled and annotated into 19,622 sequences which we believe cover most of the M. edulis hemocytes transcriptome. These sequences were successfully assigned to biological process, cellular component, and molecular function Gene Ontology (GO) categories. Several transcripts related to immunity and stress such as some fibrinogen related proteins and Toll-like receptors, the complement C1qDC, some antioxidant enzymes and antimicrobial peptides have already been identified. In addition, Toll-like receptors signaling pathways and the lysosome and apoptosis mechanisms were compared to KEGG reference pathways. As an attempt for large scale RNA sequencing, this study focuses on identifying and annotating transcripts from M. edulis hemocytes regulated during an in vitro experimental challenge with V. splendidus. The bioinformatic analysis provided a reference transcriptome, which could be used in studies aiming to quantify the level of transcripts using high-throughput analysis such as RNA-Seq