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ABSTRACT: Seven mother-pup pairs of harp seal (Phoca groenlandica) were sampled during the lactation season near Magdalen Islands, QC, Canada. The blubber and serum of pups and mothers as well as the milk of mothers were analyzed for polybrominated diphenyl ethers and several chlorinated persistent organic pollutants (POPs) to evaluate their transfer prior to weaning. Principal component analysis demonstrated significant variations in contaminant distribution patterns between seal tissues of mothers and pups. The selectivity in the transfer of POPs between mothers and pups appeared mainly driven by their log K(ow) (octanol/water partition coefficient). The most selective transfer step for the POPs examined occurred between the blubber and the serum of the mother. A novel approach to examine temporal changes of POP concentrations in tissues of seals which take into account the contamination of mothers was developed. A general decrease of POP concentrations in pup tissues throughout lactation may suggest a growth dilution. A concomitant rise of POP concentrations was observed in maternal blubber and serum and in milk as lactation progresses. The intensive offloading of contaminants via lactation constitutes a major but selective excretory route for reproductive female seals and also a significant route of exposure for suckling pup seals.
Science of The Total Environment 02/2012; 417-418:98-107. · 3.29 Impact Factor
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ABSTRACT: Municipal wastewaters are major sources of pollution for the aquatic biota. The purpose of this study was to determine the levels of some pharmaceutical products and the immunotoxic potential of a municipal wastewater aeration lagoon for the treatment of the domestic wastewaters of a small town with wastewater inputs from a 400-bed hospital complex. Endemic mussels were collected, caged and placed in the final aeration lagoon and at sites 1 km upstream and 1 km downstream of the effluent outfall in the receiving river for a period of 14 days. The results showed that the final aeration lagoon contained high levels of total coliforms, conductivity and low dissolved oxygen (2.9 mg/L) as well as detectable amounts of trimethoprim, carbamazepine, gemfibrozil, and norfloxacin at concentrations exceeding 50 ng/L. The lagoon effluent was indeed toxic to the mussel specimens, as evidenced by the appearance of mortality after 14 days (10% mortality), decreased mussel weight-to-shell-length ratio and loss of hemocyte viability. The number of adhering hemocytes, phagocytic activity, total nitrite levels and arachidonic cyclooxygenase activity were significantly higher in mussels placed in the final aeration lagoon. A multivariate analysis also revealed that water pH, conductivity, total coliforms and dissolved oxygen were the endpoints most closely linked with phagocytic activity, the amount of adhering hemocytes and loss of hemocyte viability. In conclusion, exposure of mussels to treated aerated lagoon wastewater is deleterious to freshwater mussels where the immune system is compromised.
Journal of Environmental Sciences 01/2012; 24(5):781-9. · 1.66 Impact Factor
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ABSTRACT: Serum and blubber of pup harbor (Phoca vitulina), grey (Halichoerus grypus) and harp (Phoca groenlandica) seals from the Estuary and the Gulf of St. Lawrence were analyzed for polybrominated diphenyl ethers (PBDEs). Concentrations of ∑PBDEs (on lipid weight basis) in tissues of harbor seal pups inhabiting the St. Lawrence Estuary were about five times higher than in those from a colony located in the northern Gulf. Harp seal pups have the lowest levels of ∑PBDEs among the seal species born in the Gulf of St. Lawrence. Lipid normalized concentrations of ∑PBDEs in serum and blubber were strongly correlated, suggesting that the blood collection as a less invasive method could be used to monitor ∑PBDEs in pups. This study shows that fluvial inputs of PBDEs are important to the St. Lawrence marine ecosystem and that inhabiting harbor seal pups have a substantial exposure to PBDEs at a critical developmental stage. In addition, the observed difference in PBDE levels between harp and grey or harbor seal pups from the Gulf of St. Lawrence is explained by the difference in diets of their mothers which is linked with their residency time in the Gulf and their seasonal migration pattern.
Chemosphere 01/2011; 82(5):663-9. · 3.21 Impact Factor
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ABSTRACT: Although, heavy metals and polycyclic aromatic hydrocarbons (PAHs) have been reported at high levels in marine mammals, little is known about the toxic effects of some of these contaminants. In this study, we assessed the immunotoxic and genotoxic effects of seven heavy metals (arsenic, vanadium, selenium, iron, zinc, silver and chromium) and one PAH (benzo[a]pyrene or B[a]P) on a lymphoma B cell line from harbour seal (Phoca vitulina). A significant reduction in lymphocyte proliferation was registered following an exposure to 0.05 microM of B[a]P, 5 microM of arsenic or selenium, 50 microM of vanadium, 100 microM of silver and 200 microM of iron. On the contrary, zinc increased the lymphoproliferative response at 200 microM. Decreased phagocytosis was observed at 20 microM of arsenic, 50 microM of B[a]P or selenium, 200 microM of zinc and 500 microM of vanadium. Micronuclei induction occurred with 0.2 microM of B[a]P, 100 microM of vanadium and with 200muM of arsenic or selenium. Exposure to 50muM of arsenic decreased G(2)/M phase of the cell cycle. Chromium did not induce any effects at the concentrations tested. Concentrations of heavy metals (except silver and vanadium) and B[a]P inducing an toxic effect are within the environmental ranges reported in the blood tissue of pinnipeds. The reduction of some functional activities of the harbour seal immune system may cause a significant weakness capable of altering host resistance to disease in free-ranging pinnipeds.
Toxicology 04/2010; 270(2-3):66-76. · 3.68 Impact Factor
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ABSTRACT: Effects of polybrominated diphenyl ethers (PBDEs) on the immune system of marine mammals are poorly understood. One important innate immune function of granulocytes is the respiratory burst which generates reactive oxygen species (ROS) used to kill engulfed microorganisms. The present study investigates in vitro the effects of BDE-47, -99 and -153, on the formation of ROS, on intracellular level of thiols, on activity and efficiency of phagocytosis and on apoptosis in granulocytes of harbour seals. Compounds were tested at four different concentrations ranging from 1.5 to 12 microM. Results showed that ROS levels, thiol levels and phagocytosis were all affected when harbour seal cells were exposed to the highest concentration (12 microM) of PBDE congeners. Apoptosis was not affected by PBDEs. The observed effects were similar in adults, pups and in the 11B7501 cell line of harbour seals.
Marine pollution bulletin 10/2009; 60(2):291-8. · 2.63 Impact Factor
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ABSTRACT: Knowledge on pinniped immunology is still in its infancy. For instance, age-related and developmental aspects of the immune system in pinnipeds need to be better described. The present study examined the phagocytic activity and efficiency of harbour, grey and harp seal leukocytes. In the first part of the study, peripheral blood was collected from captive female harbour seals of various ages. Data showed an age-related decrease in phagocytosis in female harbour seals from sub-adult to adulthood. In the second part of the study, changes in phagocytosis were quantified during lactation in wild newborn harbour, grey and harp seals and in their mothers (harp and grey seals). In newborns of the same age, leukocytes of harbour and harp seals phagocytosed less than those of grey seal pups. The phagocytic activity and efficiency increased significantly from early to mid-lactation in newborn harbour seals, and from early to late lactation in newborn grey seals, which could suggest that the transfer of phagocytosis-promoting factor(s) in colostrum is an important feature of temporary protection for pups. In contrast, no changes in phagocytic activity and efficiency were observed in lactating females of the two seal species, harp and grey, examined. At late lactation, phagocytic activity in both grey and harp seal pups and phagocytic efficiency in grey seal pups were significantly higher than in their mothers. These results could reflect either the capacity of phagocytes of the newborn harp and grey seals to respond to pathogens. Results from this study suggest that the phagocytosis of the seal species examined is not fully developed at birth as it generally increases in pups during lactation. Thereafter, the phagocytic activity of seals appears to decrease throughout adulthood.
Veterinary Immunology and Immunopathology 09/2009; 134(3-4):160-8. · 2.08 Impact Factor
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ABSTRACT: Animals in poor health condition are not relevant biological models. The current study focused on the use of the clearance rate of Mytilus edulis to assess the gross physiological condition of individuals maintained in stressful experimental conditions. This approach was developed in a new, highly controlled experimental exposure device designed to investigate individual responses in aquatic ecotoxicological studies. Both clearance rate values and immune parameters analysis indicated that the health condition of mussels kept in 50ml tubes for 24h or 48h was not altered compared to controls, while most parameters were depressed after 72h. Moreover, this study confirms the relevance of flow cytometric for the measurement of clearance rate compared to techniques utilizing microscopy. Current results prompted us to perform further 24h chemical exposure using this "in tubo" device.
Environmental Pollution 06/2008; 153(2):492-6. · 3.75 Impact Factor
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ABSTRACT: Biological 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 10(-6)M, while acute exposures showed significant inhibition of phagocytosis at 10(-4)M and 10(-3)M. In sub-acute exposures both circulating haemocytes and haemocyte mortality increased at 10(-4)M and 10(-3)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.
Environmental Pollution 06/2008; 153(2):416-23. · 3.75 Impact Factor
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ABSTRACT: Effects of tributyltin (TBT), dibutyltin (DBT), and monobutyltin (MBT) on the in vitro phagocytic activity of hemocytes from three marine bivalve species, Mytilus edulis, Mya arenaria, and Mactromeris polynyma, were determined using flow cytometry. Phagocytosis was reduced with increasing doses of TBT and DBT. The toxicity of butyltins on hemocytes decreased in the order DBT > TBT > MBT, and comparison of the relative sensitivity of the three species showed that blue mussels (M. edulis) were more tolerant of butyltin compounds than both clam species. Toxicity mechanisms of butyltins are discussed and compared to those of other metals.
Environmental Toxicology and Chemistry 02/1999; 18(3):519 - 522. · 2.81 Impact Factor
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ABSTRACT: The widespread environmental contamination, bioaccumulation and endocrine disruptor effects of butyltins (BTs) to wildlife are well documented. Although suspected, potential effects of BTs exposure on the immune system of marine mammals have been little investigated. In this study, we assessed the effects of tributyltin (TBT) and its dealkylated metabolites dibutyltin (DBT) and monobutyltin (MBT) on the immune responses of harbour seals. Peripheral blood mononuclear cells isolated from pup and adult harbour seals were exposed in vitro to varying concentrations of BTs. DBT resulted in a significant decrease at 100 and 200 nM of phagocytotic activity and reduced significantly phagocytic efficiency at 200 nM in adult seals. There was no effect in phagocytosis with TBT and MBT. In pups, the highest concentration (200 nM) of DBT inhibited phagocytic efficiency. A reduction of tumor-killing capacity of adult natural killer (NK) cells occurred when leukocytes were incubated in vitro with 50 nM DBT and 200 nM TBT for 24 h. In adult seals, T-lymphocyte proliferation was significantly suppressed when the cells were exposed to 200 nM TBT and 100 nM DBT. In pups, the proliferative response increased after an exposure to 100 nM TBT and 50 nM DBT, but decreased with 200 nM TBT and 100 nM DBT. The immune functions were more affected by BTs exposure in adults than in pups, suggesting that other unsuspected mechanisms could trigger immune parameters in pups. The toxic potential of BTs followed the order of DBT > TBT > MBT. BT concentrations of harbour seal pups from the St. Lawrence Estuary (Bic National Park) ranged between 0.1–0.4 ng Sn/g wet weight (ww) and 1.2–13.4 ng Sn/g ww in blood and blubber, respectively. For these animals, DBT concentrations were consistently below the quantification limit of 0.04 ng Sn/g ww in blood and 0.2 ng Sn/g ww in blubber. Results suggest that concentrations measured in pups are considered too low to induce toxic effects to their immune system during first days of life. However, based on our in vitro results, we hypothesize that BTs, and DBT in particular, could pose a serious threat to the immune functions in free-ranging harbour seal adults.
Aquatic Toxicology.
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ABSTRACT: During the last two decades, knowledge of shellfish immunology has been largely improved and the immune status of bivalves can be assessed by the measurement of both cellular and humoral parameters. Previous monitoring studies which the immune status of bivalve molluscs has been assessed have demonstrated that many parameters may vary greatly among sites and seasons, suggesting that environmental and endogenous factors may affect this system. Reproduction may also interfere with the immune system. This study focuses on the seasonal variations of the immune parameters in two batches of Pacific oysters differing by their ploidy, diploid′s and triploid′s. The oysters were sampled from a French oyster farm over two reproductive periods. Selected immune parameters investigating haemocyte integrity and immunocompetency were analysed monthly by flow cytometry. Histological observations were made in gonads to discriminate gender and gametogenesis stages. Results indicate that immune parameters in both diploid and triploid oysters exhibited marked seasonal variations. Phagocytosis index was significantly low during spawning before reaching a maximum in autumn. Triploids also appeared to be less sensitive to environmental cues than diploids. Taken as a whole, alterations observed in maturing individuals corresponded to a depressed immune status in late spring, at a time corresponding to the spawning period. Furthermore, grouping by sex of ongoing gametogenesis individuals revealed uneven immune alterations among males and females. Finally, grouping sexual maturation stages showed evidence of a peculiar stressful event during early gametogenesis, perhaps under endogenous control.
Aquaculture.
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ABSTRACT: Sediments of Baie des Anglais on the St. Lawrence estuary have a history of environmental contamination, but little information exists regarding their toxicity. The purpose of the present study was to determine the effects of contaminated Baie des Anglais sediments on American plaice (Hippoglossoides platessoides) immune function. Three sites in Baie des Anglais were selected which vary in proximity to local industries and in their sediment contaminant load. Sites 1 and 2 (within the bay) are the closest to shore and most heavily contaminated while sediments at Site 3, which is outside the bay, are the least contaminated. In the first experiment, American plaice were placed in cages at each site for three weeks and immune function was assessed by measuring the phagocytic activity of pronephric macrophages. At the time of sampling, plaice displayed pronephros cell immune response disturbances indicating that Site 1 and 2 were most toxic and Site 3 the least toxic. The results obtained for phagocytosis revealed that contaminants present in the sediments are bioavailable to fish, which came in contact with them and significantly affected their immune system. In the second experiment, sediments from the most toxic site, Site 1, were collected for a laboratory controlled experiment in which plaice were exposed for up to 3 months to these contaminated marine sediments, while the control group was exposed to relatively uncontaminated beach sand. At the end of the exposure period, plaice were transferred from contaminated sediment to beach sand and sampled one month later in order to determine if immune function had returned to control levels. The total number of macrophages decreased following three months of exposure, while the active macrophages had already decreased after the first month of exposure. Following the rehabilitation period a significant trend toward normal response was noted. Sediments from Baie des Anglais contain primarily less highly chlorinated PCBs and lower concentrations of the intermediate and highly chlorinated PCBs. The total concentration of PCBs (sum of 20 congeners) in the contaminated sediments was 1500 ng/g while in the beach sand, the levels were 13.6 ng/g dry weight. Only the low chlorinated PCB congeners were efficiently transferred from the sediments to the plaice liver. Together, these results suggest that the effect of chemical exposure on the phagocytosis of plaice macrophages may be reversible if the fish are returned to a non-contaminated habitat.
Chemosphere.
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ABSTRACT: Silica-supported hexamolybdate catalysts prepared by impregnation and two series obtained by calcination of the former are studied by different physicochemical techniques (IR and Raman spectroscopies, X-ray diffraction, and electronic microscopy) and tested in the catalytic oxidation of methanol. The nature of the surface species and the effect of water on the calcined catalysts are discussed as a function of the Mo loading (3 to 25 wt% Mo) from solid-state characterization and catalytic behavior. The catalysts unexposed to water (series 1) essentially exhibit a redox catalytic behavior, while the water-exposed catalysts (series 2) exhibit an acidic behavior. At high coverages (≥ 10 wt% MO), MoO3 is the main species present on the surface. At lower coverages, a molybdenum oxo species is formed which is mainly responsible for the catalytic activity. This species is constituted of trimolybdic groups, fragments of the Keggin unit SiMo12, in interaction with silica. Upon prolonged exposure to water, 12-molybdosilicic acid is also detected, but plays a minor role in the catalytic reaction.
Journal of Catalysis. 125(2):292-310.
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ABSTRACT: Hydrocracking (HCK) Nickel-Tungsten catalysts, supported on amorphous silica alumina, have been prepared by incipient wetness impregnation with new starting materials based on Keggin or on the derived lacunary Keggin heteropolyanion (HPA) structure and were compared to conventional catalysts. After calcination a polytungstate phase evidenced by Raman spectroscopy was generally observed indicating the destruction of the initial HPA. The sulfided solids were characterized by HRTEM to determine the dispersion of the WS2 active phase. A careful XPS study indicated a better promoting effect for HPA based catalysts compared to their conventional counterparts. Toluene hydrogenation catalytic performances were related to the sulfided solids characterizations. Ni4SiW11O39 nickel salt appeared to be the most efficient precursor that led to high dispersion and higher promoting effect due to the proximity of Ni and W in the heteropolyanion salt with an optimum Ni/W ratio.
Catalysis Today 150:207-212. · 3.41 Impact Factor
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ABSTRACT: Thermal behavior of unsupported and silica-supported 12-molybdosilicic acid (with Mo loadings of 17.6 and 9 wt%) are studied by IR spectrometry and catalytic reactivity in the methanol oxidation reaction. In the case of the unsupported acid (SiMo12H), IR and catalytic reactivity measurements show that the destruction of the Keggin unit is rather abrupt in the temperature range 300–320°C (collapse of the acidic character in catalysis, formation of Mo03 evidenced by IR). The thermal stability of SiMo12H is reduced by ∼20–30°C when supported on silica, and the destruction of the Keggin unit extends over a larger temperature range. The nature of the Mo oxo species responsible for the redox activity after thermal treatments at temperatures higher than 330°C is discussed.
Journal of Catalysis. 126(2):591-599.
