References of "Das, Krishna"
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See detailOrganochlorine pesticides, polychlorinated biphenyls and trace elements in wild European sea bass (Dicentrarchus labrax) off European estuaries
Schnitzler, Joseph ULg; Thomé, Jean-Pierre ULg; Lepage, Mario et al

in Science of the Total Environment (2011), 409(19), 3680-3686

Polychlorinated biphenyls (PCBs) and organochlorine pesticides like dichloro-diphenyl-trichloroethane (DDTs), hexachlorocyclohexanes (HCHs), aldrin, dieldrin and trace elements (Cd, Cu, Se, Pb, Zn and Hg ... [more ▼]

Polychlorinated biphenyls (PCBs) and organochlorine pesticides like dichloro-diphenyl-trichloroethane (DDTs), hexachlorocyclohexanes (HCHs), aldrin, dieldrin and trace elements (Cd, Cu, Se, Pb, Zn and Hg) were analysed in the muscle of European sea bass (Dicentrarchus labrax) sampled in Atlantic coastal regions near several important European river mouths (Gironde, Charente, Loire, Seine and Scheldt). High contamination levels were measured in the muscles of European sea bass sampled in the coastal regions near those river mouths (e.g. Σ ICES PCB=133–10,478 μg kg−1 lw and Hg=250–2000 μg kg−1 dw). The Scheldt and the Seine are still among the most contaminated estuaries in Europe. Each region presented their specific contamination patterns reflecting different sources due to the input of the respective rivers. As fish and fishery products are the main contributors of the total dietary intake of organochlorinated pollutants, regular consumption of European sea bass with the reported contamination levels may represent a significant exposure route for the general human population. [less ▲]

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See detailPOTENTIAL EFFECTS OF BLOOD CONTAMINANTS ON IMMUNE RESPONSES IN HARBOUR SEALS (PHOCA VITULINA)
Dupont, Aurélie ULg; Weijs, Liesbeth; Siebert, Ursula et al

in Organohalogen Compounds (2011), 73

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See detailNew evidence of a relationship between PCB and the cause of death of North Sea harbour porpoises
Jauniaux, Thierry ULg; Das, Krishna ULg; Haelters, Jan et al

in proceeding of the annual conference (2011)

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See detailThyroid dysfunction in sea bass (Dicentrarchus labrax): Underlying mechanisms and effects of polychlorinated biphenyls on thyroid hormone physiology and metabolism
Schnitzler, Joseph ULg; Celis, Niko; Klaren, Peter et al

in Aquatic Toxicology (2011), 105

The current study examines the effect of subchronic exposure to a mixture of Aroclor standards on thyroid hormone physiology and metabolism in juvenile sea bass. The contaminant mixture was formulated to ... [more ▼]

The current study examines the effect of subchronic exposure to a mixture of Aroclor standards on thyroid hormone physiology and metabolism in juvenile sea bass. The contaminant mixture was formulated to reflect the persistent organic pollution to which the European sea bass population could conceivably be exposed (0.3, 0.6 and 1.0 g 7PCBs per g food pellets) and higher (10 g 7PCBs per g food pellets). After 120 days of exposure, histomorphometry of thyroid tissue, muscular thyroid hormone concentration and activity of enzymes involved in metabolism of thyroid hormones were assessed. Mean concentrations of 8, 86, 142, 214 and 2279 ng g−1 ww ( 7 ICES PCB congeners) were determined after 120 days exposure. The results show that the effects of PCB exposures on the thyroid system are dose-dependent. Exposure to environmentally relevant doses of PCB (0.3–1.0 g 7PCBs per g food pellets) induced a larger variability of the follicle diameter and stimulated hepatic T4 outer ring deiodinase. Muscular thyroid hormone levels were preserved thanks to the PCB induced changes in T4 dynamics. At 10 times higher concentrations (10 g 7PCBs per g food pellets) an important depression of T3 and T4 levels could be observed which are apparently caused by degenerative histological changes in the thyroid tissue. [less ▲]

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See detailSTRATEGY FOR ASSESSING IMPACTS OF THYROID DISRUPTING CHEMICALS IN TELEOSTEANS
Schnitzler, Joseph ULg; Klaren, Peter; Celis, Niko et al

in Organohalogen Compounds (2011)

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See detailStable isotopes of captive Cetaceans (Killer Whales and Bottlenose dolphins)
Caut, Stéphane; Laran, Sophie; Garcia-Hartmann, Emmanuel et al

in Journal of Experimental Biology (2011), 214

There is currently a great deal of interest in using stable-isotope methods to investigate diet, trophic level and migration movement in wild cetaceans. Fundamental to the interpretation of these methods ... [more ▼]

There is currently a great deal of interest in using stable-isotope methods to investigate diet, trophic level and migration movement in wild cetaceans. Fundamental to the interpretation of these methods is the need to understand how diet isotopic values are reflected in consumer tissues. In this study, we investigated patterns of isotopic discrimination between diet and blood constituents of two species of cetaceans (killer whale, Orcinus orca and 19 bottlenose dolphin, Tursiops truncutus) fed with controlled diets during 350 days. Diet discrimination factors ( ) for plasma were estimated to 13C =2.3‰ and 1520 N =1.8‰ respectively for both species and to 13C =2.7‰ and 1521 N =0.5‰ for red blood cells (RBC). Delipidation had no significant effect on carbon and nitrogen isotopic values of blood constituents, confirming that cetacean blood no serving as reservoirs of lipids. In contrast, carbon isotopic values are higher in delipidated samples of blubber, liver and muscle of orca tissues. The mean half life for plasma was 32.9 days for killer whales and 27.2 days for bottlenose dolphin and for RBC was greater than 175 days. The potential for conflict between fisheries and cetaceans has heightened the need for trophic information about this taxa within those ecosystems. These results provide the first published stable isotope turnover rates and discrimination factors for cetaceans, which are essential if conclusions are to be drawn on issues concerning trophic structures, carbon sources and diet reconstruction. [less ▲]

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See detailA non-invasive approach to study lifetime exposure and bioaccumulation of PCBs in protected marine mammals: PBPK modeling in harbor porpoises
Weijs, Liesbeth; Covaci, Adrian; Yang, Raymond S. H. et al

in Toxicology and Applied Pharmacology (2011), In Press, Corrected Proof

In the last decade, physiologically based pharmacokinetic (PBPK) models have increasingly been developed to explain the kinetics of environmental pollutants in wildlife. For marine mammals specifically ... [more ▼]

In the last decade, physiologically based pharmacokinetic (PBPK) models have increasingly been developed to explain the kinetics of environmental pollutants in wildlife. For marine mammals specifically, these models provide a new, non-destructive tool that enables the integration of biomonitoring activities and in vitro studies. The goals of the present study were firstly to develop PBPK models for several environmental relevant PCB congeners in harbor porpoises (Phocoena phocoena), a species that is sensitive to pollution because of its limited metabolic capacity for pollutant transformation. These models were tested using tissue data of porpoises from the Black Sea. Secondly, the predictive power of the models was investigated for time trends in the PCB concentrations in North Sea harbor porpoises between 1990 and 2008. Thirdly, attempts were made to assess metabolic capacities of harbor porpoises for the investigated PCBs. In general, results show that parameter values from other species (rodents, humans) are not always suitable in marine mammal models, most probably due to differences in physiology and exposure. The PCB 149 levels decrease the fastest in male harbor porpoises from the North Sea in a time period of 18†years, whereas the PCB 101 levels decrease the slowest. According to the models, metabolic breakdown of PCB 118 is probably of lesser importance compared to other elimination pathways. For PCB 101 and 149 however, the presence of their metabolites can be attributed to bioaccumulation of metabolites from the prey and to metabolic breakdown of the parent compounds in the harbor porpoises. [less ▲]

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See detailRelationship between PCB 153 and stable nitrogen in a Guiana dolphin (Sotalia guianensis) food weeb, Gunabara Bay, Brazil
Vidal, L. G.; Bisi, T. L.; Dorneles, P. R. et al

in Organohalogen Compounds (2011)

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See detailPCBs versus PBDEs: how similar compounds can behave differently in harbour porpoises
Weijs, Liesbeth; Yang, R. S. H.; Das, Krishna ULg et al

in Organohalogen Compounds (2011)

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See detailMaternal transfer of PCBs, PBDEs and their hydroxylated metabolites in grey seal (Halichoerus grypus) from the Isle of May, Scotland
Vanden Berghe, Marie; Weijs, Liesbeth; Habran, Sarah ULg et al

in Organohalogen Compounds (2011)

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See detailToothed whales in the northwestern Mediterranean: Insight into their feeding ecology using chemical tracers
Praca, Emilie; Laran, Sophie; Lepoint, Gilles ULg et al

in Marine Pollution Bulletin (2011), 62(5), 1058-1065

Risso’s dolphins, pilot whales and sperm whales rarely strand in the northwestern Mediterranean. Thus, their feeding ecology, through the analysis of stomach contents, is poorly known. The aim of this ... [more ▼]

Risso’s dolphins, pilot whales and sperm whales rarely strand in the northwestern Mediterranean. Thus, their feeding ecology, through the analysis of stomach contents, is poorly known. The aim of this study was to gain further insight into the segregation/superposition of the diet and habitat of Risso’s dolphins, pilot whales and sperm whales using chemical tracers, namely, stable isotopes (d13C, d15N) and orga- nochlorines. Significantly different d15N values were obtained in Risso’s dolphins (11.7 ± 0.7‰), sperm whales (10.8 ± 0.3‰) and pilot whales (9.8 ± 0.3‰), revealing different trophic levels. These differences are presumably due to various proportions of Histioteuthidae cephalopods in each toothed whale’s diet. Similar d13C contents between species indicated long-term habitat superposition or corroborated impor- tant seasonal migrations. Lower congener 180 concentrations (8.20 vs. 21.73 lg.g􏰀1 lw) and higher tDDT/ tPCB ratios (0.93 vs. 0.42) were observed in sperm whales compared with Risso’s dolphins and may indi- cate wider migrations for the former. Therefore, competition between these species seems to depend on different trophic levels and migration patterns. [less ▲]

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See detailUse of stable isotopes to study pollutants in marine vertebrates
Das, Krishna ULg

Conference (2010, November 11)

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See detailEssential and non-essential elements in the eggs of sea turtles from the Lesser Antilles
Leroy, Céline; Dyc, Christelle ULg; Bouquegneau, Jean-Marie ULg et al

Poster (2010, October)

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See detailAssessment of gestation, lactation and fasting on stable isotope ratios in northern elephant seals (Mirounga angustirostris)
Habran, Sarah ULg; Debier, Cathy; Crocker, Dan E. et al

in Marine Mammal Sciences (2010), 26(4), 880-895

Effects of physiological processes such as gestation, lactation and nutritional stress on stable isotope ratios remain poorly understood. To determine their impact, we investigated these processes in ... [more ▼]

Effects of physiological processes such as gestation, lactation and nutritional stress on stable isotope ratios remain poorly understood. To determine their impact, we investigated these processes in simultaneously fasting and lactating northern elephant seals (Mirounga angustirostris). Stable carbon and nitrogen isotope values were measured in blood and milk of 10 mother-pup pairs on days 5 and 22 of lactation. As long- and short-term integrators of diet, blood cells and serum may reflect foraging data or energy reserves from late gestation and lactation, respectively. Limited changes in isotopic signatures of maternal blood over the lactating period were highlighted. Nitrogen isotope fractionation associated with mother-to-offspring transfer of nutrients was generated between mother and offspring during gestation and lactation. This fractionation was tissue and time-specific, it varied between early and late lactation from +0.6‰ to +1.3‰ in blood cells and from +1.1‰ to nonsignificant value in serum. Therefore, if pups appear to be good proxies to investigate the female trophic ecology especially for C sources, much more caution is required in using δ15N values. Further studies are also needed to better define the relative impact of fasting and lactation on the enrichment or depletion of isotopes in different tissues. [less ▲]

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See detailMethylmercury and selenium in vitro effects on harbor seal (Phoca vitulina) lymphocytes : a multidisciplinary approach
Dupont, Aurélie ULg; Bouquegneau, Jean-Marie ULg; Das, Krishna ULg et al

Poster (2010, May 26)

Methylmercury (MeHg) bioaccumulates along the food web, leading to the highest levels in tissues of predatory species. It constitutes the predominant form present in the blood of marine mammals. The blood ... [more ▼]

Methylmercury (MeHg) bioaccumulates along the food web, leading to the highest levels in tissues of predatory species. It constitutes the predominant form present in the blood of marine mammals. The blood cells, including the immune cells, are therefore exposed to the toxic properties of that chemical. Nevertheless, selenium (Se) is an essential element absorbed concomitantly to MeHg which seems to modulate this toxicity. The goal of this study is to evaluate the immunotoxicity of MeHg on the harbor seal (Phoca vitulina) T lymphocytes, highly important in the adaptive immune response, and to investigate the modulating effect of Se on that toxicity. In parallel, the concentrations of MeHg, total mercury (T-Hg) and Se are determined in free-ranging harbour seal blood in order to follow their contamination levels. The T lymphocytes were isolated from the whole blood, exposed to various MeHg and Se concentrations and the exposure effects were estimated by functional tests including the evaluation of viability, proliferation, metabolic activity, DNA and protein synthesis, and by morphological analysis by transmission electron microscopy. The mean T-Hg concentration was 172 ± 143 µg/l of whole blood. The T lymphocytes cultures in vitro displayed a decreasing number of viable cells with increasing concentrations of MeHg, and numerous ultrastructural defects. The cells exposed to MeHg notably displayed distortion of the plasmic membrane, nucleus fragmentations, chromatin compaction, swelling mitochondrias and cytoplasmic vacuolisations. Those results highlighted various immunotoxic effects of MeHg, both at the functional and ultrastructural levels. The antagonistic role of Se on MeHg immunotoxicity is discussed. [less ▲]

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See detailMaternal transfer of trace metals to offspring in grey seals
Habran, Sarah ULg; Pomeroy, Paddy; Debier, Cathy et al

Conference (2010, May 25)

Marine mammals may display high heavy metal levels in their tissues, which raises the question of the importance of toxic metal transfer from mother to offspring. Some lactating female phocids fast during ... [more ▼]

Marine mammals may display high heavy metal levels in their tissues, which raises the question of the importance of toxic metal transfer from mother to offspring. Some lactating female phocids fast during the suckling period. This fasting period involves not only an important mobilization of energy reserves, but also mobilization of potentially associated contaminants. We studied maternal transfer of trace metals to offspring in the grey seal (Halichoerus grypus). Trace metal concentrations were measured in whole blood, milk and hair of mother-pup pairs in early and late lactation. Metal levels in blood decreased according to the following pattern: Fe > Zn > Se > Cu > Hg > Pb > Cr > V in mothers and pups. Cd and Ni were not detected and V, Cr and Pb levels were very low in maternal and pup blood. However, Ni and Pb levels were detected in the milk showing a transmammary transfer of these metals. Hg levels in blood and milk were higher than levels of previous metals and levels varied significantly throughout lactation. The increasing maternal levels over lactation were likely due to the remobilization of energy reserves during fasting and milk production in mothers causing a Hg release in blood. All metals were detected in hair and lanugo according to the following pattern: Fe > Zn > Hg > Cu > Se > Ni > V > Pb > Cd > Cr in mothers and Zn > Fe > Hg > Se > Cu > Pb > Ni > V > Cr > Cd in pups. Pb levels were relatively high in comparison with other phocid species. Only Hg showed a significant relationship between hair/lanugo and blood levels. This study highlights (i) a transplacental and transmammary transfer of metals in grey seals, and shows that (ii) physiological processes such as lactation and/or fasting can modify trace metal levels in the blood of mothers and pups. [less ▲]

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