The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
J Pellerin - One of the best experts on this subject based on the ideXlab platform.
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oxidative stress and immunologic responses following a dietary exposure to pahs in Mya arenaria
Chemistry Central Journal, 2008Co-Authors: Nicolas Pichaud, J Pellerin, Michel Fournier, S Gauthierclerc, Pascal Rioux, Emilien PelletierAbstract: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, Mya arenaria. 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 in situ in organisms sampled in a control site (Metis Beach, Quebec, Canada) as well as organisms sampled in a site receiving domestic effluents (Pointe-au-Pere, Quebec, Canada), to assess effects of abiotic variables related to seasonal variations and mixed contamination on the selected parameters. 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. 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 in situ survey (in the natural environment) suggested that clams from the Pointe-au-Pere 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.
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physiological effects of polycyclic aromatic hydrocarbons on soft shell clam Mya arenaria
Aquatic Toxicology, 2007Co-Authors: H Frouin, J Pellerin, Michel Fournier, Emilien Pelletier, P Richard, Nicolas Pichaud, C Rouleau, Florent GarnerotAbstract:Abstract The aim of this study was to investigate the effects of polycyclic aromatic hydrocarbons (PAHs) on the physiological status of the bivalve Mya arenaria. Specimens were exposed to four different sources of PAHs: aluminium smelter soot, sediment from an industrial discharge pound, charcoal fine particles and dietary PAHs assessed by feeding clams with phytoplankton freshly impregnated with dissolved PAHs. The exposure period lasted 30 days and bivalves were let to recover for an additional 20 days. At days 8, 15, 30 and 50, immune parameters (phagocytic activity and efficiency) were monitored in haemocytes. Oxidative stress measures such as catalase and lipid peroxidation were quantified in digestive gland as well as concentrations of bioaccumulated PAHs. In a second experiment, clams were exposed to [14C]-pyrene via the phytoplankton, and the tissue distribution of radiolabelled compound was studied. Glycogen levels in gonad and digestive gland were also measured and gametogenesis stages were investigated. Results showed a high bioaccumulation in clams exposed to dietary PAHs and contaminated sediments. Tissue distribution of [14C]-pyrene revealed that the radiolabelled compound persisted mainly in the gonad during 14 days. A decrease of phagocytosis was observed in contaminated male clams. The lipid peroxidation (malondialdehyde) was found to increase in the digestive gland tissues of clams exposed to dietary PAHs, smelter soot and discharge, but no differences were observed in the catalase activity. A delay in gametogenesis occurred in all exposed males and in females contaminated with coke dust and dietary PAHs. Males were more sensitive than females to PAH exposure. A dysfunction in steroid synthesis is suspected to occur due to the exposure to all sources of PAHs.
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seasonal gonad progesterone pattern in the soft shell clam Mya arenaria
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2002Co-Authors: A Siah, J Pellerin, A Benosman, Jeanpierre Gagne, J C AmiardAbstract:Steroidogenesis, which plays a major role in the reproductive cycle of vertebrates, is still for the most part, unknown in invertebrates. The aim of this study was to examine the link between progesterone and the reproductive cycle in Mya arenaria. The soft-shell clams, Mya arenaria were collected in Anse a l'Orignal (Parc Provincial du Bic, Quebec, Canada) from July to November 1998. Histological data have shown that female gonads of M. arenaria were in the spawning stage in August and September, while the male gonads were in the ripe stage. This period of active gametogenesis was associated with a depletion of lipid reserves. These lipids could be used as a source of energy and as a substrate for steroidogenesis. Liquid Chromatography coupled to Mass Spectroscopy (LC-MS) and quantified by Enzyme Linked ImmunoSorbent Assay (ELISA) determined progesterone. Progesterone levels in the gonad were increased during the ripe stage in the male and during the spawning stage in the female. These results indicate, for the first time, that progesterone, as in vertebrates, may play a role in the reproductive cycle of M. arenaria.
Susana Puntarulo - One of the best experts on this subject based on the ideXlab platform.
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A kinetic approach to assess oxidative metabolism related features in the bivalve Mya arenaria
Theory in Biosciences, 2012Co-Authors: Paula Mariela Gonzalez, Doris Abele, Susana PuntaruloAbstract:Electron paramagnetic resonance uses the resonant microwave radiation absorption of paramagnetic substances to detect highly reactive and, therefore, short-lived oxygen and nitrogen centered radicals. Previously, steady state concentrations of nitric oxide, ascorbyl radical (A·) and the labile iron pool (LIP) were determined in digestive gland of freshly collected animals from the North Sea bivalve Mya arenaria . The application of a simple kinetic analysis of these data based on elemental reactions allowed us to estimate the steady state concentrations of superoxide anion, the rate of A· disappearance and the content of unsaturated lipids. This analysis applied to a marine invertebrate opens the possibility of a mechanistic understanding of the complexity of free radical and LIP interactions in a metabolically slow, cold water organism under unstressed conditions. This data can be further used as a basis to assess the cellular response to stress in a simple system as the bivalve M. arenaria that can then be compared to cells of higher organisms.
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iron and radical content in Mya arenaria possible sources of no generation
Aquatic Toxicology, 2008Co-Authors: Paula Mariela Gonzalez, Doris Abele, Susana PuntaruloAbstract:Abstract The objective of this work was to analyze oxidative metabolism in Mya arenaria. Total Fe content in M. arenaria collected in the German Wadden Sea was 1.9 ± 0.7, 0.7 ± 0.1 and 0.17 ± 0.01 nmol/mg fresh weight (FW), in digestive glands (DG), mantle and gills, respectively. Labile Fe pool, assessed by electronic paramagnetic resonance (EPR), was 146 ± 10 pmol/mg FW, and by the fluorescence method employing calcein it was 118 ± 9 pmol/mg FW. The lipid radical content in the DG, assessed by EPR, was 27 ± 7 pmol/mg FW, and the thiobarbituric reactive substances content amounted to 57 ± 8 pmol/mg FW. Ascorbyl radical (A ) content, assessed by quantification of EPR signals, was 0.04 ± 0.01 pmol/mg FW, and the ascorbate content (AH−) was 478 ± 12 pmol/mg FW. The ratio A /AH− was (8 ± 1) × 10−5 AU, suggesting a minimum oxidative stress even under physiological conditions, presumably depending on basal metabolic functions. The content of nitric oxide (NO), assessed by EPR, was 99 ± 3 pmol/mg FW. The generation rate of NO by nitric oxide synthase-like activity (NOS-like) was assayed as NO production detected by EPR in the presence of l -arginine and NADPH, and was 3.16 ± 0.06 pmol/(mg FW min). The data presented here document the detectable presence of highly reactive species in M. arenaria.
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lipid radical generation in polar laternula elliptica and temperate Mya arenaria bivalves
Comparative Biochemistry and Physiology B, 2002Co-Authors: Maria Susana Estevez, Doris Abele, Susana PuntaruloAbstract:Lipid peroxidation in Laternula elliptica was assessed employing detection of lipid radicals by electronic paramagnetic resonance measurements. The values were compared with the data from the temperate mud clam Mya arenaria. Lipid radical content was higher in the Antarctic bivalve as compared to the temperate mud clam, even within the range of its habitat temperature. The rate of generation of lipid radicals was affected by the iron content in the samples. The iron content in individual samples of digestive glands from Laternula elliptica ranged from 3 to 6 nmol g-1fwt and from Mya arenaria from 0.6 to 2.7 nmol g-1fwt. Arrhenius plots, developed from the rates obtained in the presence of 25 mM iron, showed no significant differences between the activation energy calculated for digestive glands of Laternula elliptica and Mya arenaria. The Fe3+ reduction rate by Laternula elliptica was higher than the rate measured in Mya arenaria (4.7 ± 0.9 and 1.8 ± 0.4 nmol mg-1 protein min-1, respectively). A higher content of both a-tocopherol and b-carotene was measured in Laternula elliptica as compared to Mya arenaria. The reported data suggest that increased lipid radical content in the membranes of cold adapted organisms could be also related to iron content.
J C Amiard - One of the best experts on this subject based on the ideXlab platform.
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seasonal gonad progesterone pattern in the soft shell clam Mya arenaria
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2002Co-Authors: A Siah, J Pellerin, A Benosman, Jeanpierre Gagne, J C AmiardAbstract:Steroidogenesis, which plays a major role in the reproductive cycle of vertebrates, is still for the most part, unknown in invertebrates. The aim of this study was to examine the link between progesterone and the reproductive cycle in Mya arenaria. The soft-shell clams, Mya arenaria were collected in Anse a l'Orignal (Parc Provincial du Bic, Quebec, Canada) from July to November 1998. Histological data have shown that female gonads of M. arenaria were in the spawning stage in August and September, while the male gonads were in the ripe stage. This period of active gametogenesis was associated with a depletion of lipid reserves. These lipids could be used as a source of energy and as a substrate for steroidogenesis. Liquid Chromatography coupled to Mass Spectroscopy (LC-MS) and quantified by Enzyme Linked ImmunoSorbent Assay (ELISA) determined progesterone. Progesterone levels in the gonad were increased during the ripe stage in the male and during the spawning stage in the female. These results indicate, for the first time, that progesterone, as in vertebrates, may play a role in the reproductive cycle of M. arenaria.
Hal Caswell - One of the best experts on this subject based on the ideXlab platform.
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recruitment variability and stochastic population growth of the soft shell clam Mya arenaria
Ecological Modelling, 2006Co-Authors: Bonnie J Ripley, Hal CaswellAbstract:Abstract Variability in recruitment is a striking feature of the life histories of most marine invertebrates and many fishes. The distribution of recruitment is typically lognormal rather than normal. It has been conjectured that such variation plays a major role in population growth of these species, but no complete stochastic demographic analysis has ever been reported. Here, we developed a set of deterministic and stochastic models for the clam, Mya arenaria. We constructed a size-classified, periodic matrix model to describe seasonal population dynamics, based on a mark-recapture study in Barnstable Harbor, MA, USA. In the deterministic model, an equilibrium recruitment rate of ERR = 19.4 recruits per adult was required to maintain constant population size. Periodic elasticity analysis showed that, at the ERR, fertility and larval survival accounted for 99% of the population growth rate λ . In a stochastic model with lognormally distributed recruitment, the stochastic growth rate log λ s increased with increases in either E ( log R ) or SD ( log R ) . The positive effect of SD ( log R ) is due to the highly skewed nature of the lognormal distribution. Variation in population size increases dramatically with increases in SD ( log R ) , which makes it difficult to predict future population size. If variability in recruitment is high, quasi-extinction is nearly certain even when log λ s is well above zero. Stochastic elasticity analysis shows that the contribution of adult growth and survival to λ s increases dramatically when recruitment is variable. These results suggest that, for marine invertebrates with a lognormally distributed recruitment pattern, the amount of uncertainty in recruitment should be positively associated with adult life span.
Emilien Pelletier - One of the best experts on this subject based on the ideXlab platform.
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oxidative stress and immunologic responses following a dietary exposure to pahs in Mya arenaria
Chemistry Central Journal, 2008Co-Authors: Nicolas Pichaud, J Pellerin, Michel Fournier, S Gauthierclerc, Pascal Rioux, Emilien PelletierAbstract: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, Mya arenaria. 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 in situ in organisms sampled in a control site (Metis Beach, Quebec, Canada) as well as organisms sampled in a site receiving domestic effluents (Pointe-au-Pere, Quebec, Canada), to assess effects of abiotic variables related to seasonal variations and mixed contamination on the selected parameters. 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. 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 in situ survey (in the natural environment) suggested that clams from the Pointe-au-Pere 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.
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physiological effects of polycyclic aromatic hydrocarbons on soft shell clam Mya arenaria
Aquatic Toxicology, 2007Co-Authors: H Frouin, J Pellerin, Michel Fournier, Emilien Pelletier, P Richard, Nicolas Pichaud, C Rouleau, Florent GarnerotAbstract:Abstract The aim of this study was to investigate the effects of polycyclic aromatic hydrocarbons (PAHs) on the physiological status of the bivalve Mya arenaria. Specimens were exposed to four different sources of PAHs: aluminium smelter soot, sediment from an industrial discharge pound, charcoal fine particles and dietary PAHs assessed by feeding clams with phytoplankton freshly impregnated with dissolved PAHs. The exposure period lasted 30 days and bivalves were let to recover for an additional 20 days. At days 8, 15, 30 and 50, immune parameters (phagocytic activity and efficiency) were monitored in haemocytes. Oxidative stress measures such as catalase and lipid peroxidation were quantified in digestive gland as well as concentrations of bioaccumulated PAHs. In a second experiment, clams were exposed to [14C]-pyrene via the phytoplankton, and the tissue distribution of radiolabelled compound was studied. Glycogen levels in gonad and digestive gland were also measured and gametogenesis stages were investigated. Results showed a high bioaccumulation in clams exposed to dietary PAHs and contaminated sediments. Tissue distribution of [14C]-pyrene revealed that the radiolabelled compound persisted mainly in the gonad during 14 days. A decrease of phagocytosis was observed in contaminated male clams. The lipid peroxidation (malondialdehyde) was found to increase in the digestive gland tissues of clams exposed to dietary PAHs, smelter soot and discharge, but no differences were observed in the catalase activity. A delay in gametogenesis occurred in all exposed males and in females contaminated with coke dust and dietary PAHs. Males were more sensitive than females to PAH exposure. A dysfunction in steroid synthesis is suspected to occur due to the exposure to all sources of PAHs.
