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Walter Vetter - One of the best experts on this subject based on the ideXlab platform.
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liquid chromatographic enantioseparation of the brominated flame retardant 2 3 dibromopropyl 2 4 6 tribromophenyl ether dpte and enantiomer fractions in seal blubber
Chemosphere, 2010Co-Authors: Walter Vetter, Roland Von Der Recke, Patrizia Ostrowicz, Natalie RosenfelderAbstract:Enantioselective analyses of the chiral brominated flame retardant 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE) are the focus of this work. High performance liquid chromatography (HPLC) equipped with a column that had a chiral stationary phase consisting of a modified cellulose derivative allowed for the fractionation of the enantiomers of DPTE. The enantiomeric excess was 98.2% for enantiomer 1 and 99% for enantiomer 2. Polarimetric measurements verified that the first eluting enantiomer originated from (−)-DPTE and the second peak originated from (+)-DPTE. Two gas chromatographic columns allowed for the direct enantioresolution of DPTE. The elution order of DPTE enantiomers was the same as observed in the chiral HPLC system ((−)-DPTE before (+)-DPTE). The best enantioseparation was achieved on a Chirasil-DEX CB column, which was used to analyze the enantiomer fractions of DPTE in blubber and brain samples of hooded seals (Cystophora cristata) and harp seals (Phoca Groenlandica) from the Barents and Greenland Seas. Analyses were carried out by means of gas chromatography/electron capture negative ion mass spectrometry operated in the selected ion monitoring (GC/ECNI-MS–SIM) mode. In both matrices, only minute deviations from the racemate were observed (maximum ±3% excess of (−)-DPTE). However, the samples from the Barents Sea were either racemic or showed a slight excess of (+)-DPTE (up to 2.5%), whereas all samples from the Greenland Sea contained a slight excess (up to 4%) of (−)-DPTE.
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synthesis and characterization of 2 3 dibromopropyl 2 4 6 tribromophenyl ether dpte and structurally related compounds evidenced in seal blubber and brain
Environmental Science & Technology, 2007Co-Authors: Roland Von Der Recke, Walter VetterAbstract:The unknown compound UBC-1 previously described as the major organobromine contamination in the blubber extract of a hooded seal (Cystophora cristata) from the Barents Sea was identified as 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE). DPTE, which is the main component of the brominated flame retardant (BFR) Bromkal 73-5 PE, was synthesized by electrophilic addition of bromine to allyl-2,4,6-tribromophenyl ether (ATE). The chirality of DPTE was proven by gas chromatographic enantioseparation of the synthesized racemate. On the basis of GC/ECNI-MS ion chromatograms (m/z 79 and 81), DPTE was the dominating organobromine compound in blubber and brain samples of hooded seals and harp seals (Phoca Groenlandica) from the Barents and Greenland Seas. The concentrations of DPTE in blubber and brain were up to 470 and 340 μg/kg wet weight. Next to DPTE, the natural dibromo-trichloro-monoterpene (MHC-1), the anthropogenic BDE 47 and BDE 99, as well as ATE, 3,5-dibromo-2-(2‘,4‘-dibromo)-phenoxyanisole (6-MeO-B...
Natalie Rosenfelder - One of the best experts on this subject based on the ideXlab platform.
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liquid chromatographic enantioseparation of the brominated flame retardant 2 3 dibromopropyl 2 4 6 tribromophenyl ether dpte and enantiomer fractions in seal blubber
Chemosphere, 2010Co-Authors: Walter Vetter, Roland Von Der Recke, Patrizia Ostrowicz, Natalie RosenfelderAbstract:Enantioselective analyses of the chiral brominated flame retardant 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE) are the focus of this work. High performance liquid chromatography (HPLC) equipped with a column that had a chiral stationary phase consisting of a modified cellulose derivative allowed for the fractionation of the enantiomers of DPTE. The enantiomeric excess was 98.2% for enantiomer 1 and 99% for enantiomer 2. Polarimetric measurements verified that the first eluting enantiomer originated from (−)-DPTE and the second peak originated from (+)-DPTE. Two gas chromatographic columns allowed for the direct enantioresolution of DPTE. The elution order of DPTE enantiomers was the same as observed in the chiral HPLC system ((−)-DPTE before (+)-DPTE). The best enantioseparation was achieved on a Chirasil-DEX CB column, which was used to analyze the enantiomer fractions of DPTE in blubber and brain samples of hooded seals (Cystophora cristata) and harp seals (Phoca Groenlandica) from the Barents and Greenland Seas. Analyses were carried out by means of gas chromatography/electron capture negative ion mass spectrometry operated in the selected ion monitoring (GC/ECNI-MS–SIM) mode. In both matrices, only minute deviations from the racemate were observed (maximum ±3% excess of (−)-DPTE). However, the samples from the Barents Sea were either racemic or showed a slight excess of (+)-DPTE (up to 2.5%), whereas all samples from the Greenland Sea contained a slight excess (up to 4%) of (−)-DPTE.
Roland Von Der Recke - One of the best experts on this subject based on the ideXlab platform.
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liquid chromatographic enantioseparation of the brominated flame retardant 2 3 dibromopropyl 2 4 6 tribromophenyl ether dpte and enantiomer fractions in seal blubber
Chemosphere, 2010Co-Authors: Walter Vetter, Roland Von Der Recke, Patrizia Ostrowicz, Natalie RosenfelderAbstract:Enantioselective analyses of the chiral brominated flame retardant 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE) are the focus of this work. High performance liquid chromatography (HPLC) equipped with a column that had a chiral stationary phase consisting of a modified cellulose derivative allowed for the fractionation of the enantiomers of DPTE. The enantiomeric excess was 98.2% for enantiomer 1 and 99% for enantiomer 2. Polarimetric measurements verified that the first eluting enantiomer originated from (−)-DPTE and the second peak originated from (+)-DPTE. Two gas chromatographic columns allowed for the direct enantioresolution of DPTE. The elution order of DPTE enantiomers was the same as observed in the chiral HPLC system ((−)-DPTE before (+)-DPTE). The best enantioseparation was achieved on a Chirasil-DEX CB column, which was used to analyze the enantiomer fractions of DPTE in blubber and brain samples of hooded seals (Cystophora cristata) and harp seals (Phoca Groenlandica) from the Barents and Greenland Seas. Analyses were carried out by means of gas chromatography/electron capture negative ion mass spectrometry operated in the selected ion monitoring (GC/ECNI-MS–SIM) mode. In both matrices, only minute deviations from the racemate were observed (maximum ±3% excess of (−)-DPTE). However, the samples from the Barents Sea were either racemic or showed a slight excess of (+)-DPTE (up to 2.5%), whereas all samples from the Greenland Sea contained a slight excess (up to 4%) of (−)-DPTE.
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synthesis and characterization of 2 3 dibromopropyl 2 4 6 tribromophenyl ether dpte and structurally related compounds evidenced in seal blubber and brain
Environmental Science & Technology, 2007Co-Authors: Roland Von Der Recke, Walter VetterAbstract:The unknown compound UBC-1 previously described as the major organobromine contamination in the blubber extract of a hooded seal (Cystophora cristata) from the Barents Sea was identified as 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE). DPTE, which is the main component of the brominated flame retardant (BFR) Bromkal 73-5 PE, was synthesized by electrophilic addition of bromine to allyl-2,4,6-tribromophenyl ether (ATE). The chirality of DPTE was proven by gas chromatographic enantioseparation of the synthesized racemate. On the basis of GC/ECNI-MS ion chromatograms (m/z 79 and 81), DPTE was the dominating organobromine compound in blubber and brain samples of hooded seals and harp seals (Phoca Groenlandica) from the Barents and Greenland Seas. The concentrations of DPTE in blubber and brain were up to 470 and 340 μg/kg wet weight. Next to DPTE, the natural dibromo-trichloro-monoterpene (MHC-1), the anthropogenic BDE 47 and BDE 99, as well as ATE, 3,5-dibromo-2-(2‘,4‘-dibromo)-phenoxyanisole (6-MeO-B...
Erling S. Nordøy - One of the best experts on this subject based on the ideXlab platform.
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melatonin potentiates the vasoconstrictive effect of noradrenaline in renal artery from newborn hooded seals cystophora cristata and harp seals Phoca Groenlandica
Journal of Comparative Physiology B-biochemical Systemic and Environmental Physiology, 2001Co-Authors: Jo Jorem Aarseth, Erling S. Nordøy, Karlarne StokkanAbstract:Isometric tension was recorded by force displacement transducers in ring segments of the inferior branch of the renal artery from newborn hooded seals (Cystophora cristata, n=6), harp seals (Phoca Groenlandica, n=3) and domestic pigs (Sus scrofa f. domestica, n=5). Arterial segments were mounted in heated organ baths and exposed to graded concentrations of noradrenaline (NA) and adrenaline (A), alone or together with melatonin. The melatonin concentration in the bath was similar to the plasma concentration normally found in each experimental animal. Melatonin alone did not affect the tension in any of the species, but melatonin potentiated the contraction induced by NA in hooded and harp seal arteries to a maximum of about 25% above the resting, pre-stretch level. The selective melatonin receptor antagonist luzindole reduced this potentiation by 80%. Species-specific concentrations of melatonin did not potentiate the NA-effect in the domestic pig or the A-induced contraction in any of the species. The results indicate that melatonin specifically increases the NA-sensitivity of smooth muscles in renal arteries from newborn seals. It is presumed that similar effects may operate in foetal and maternal seals and may influence their circulation during maternal diving.
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Experimental evidence of seawater drinking in juvenile hooded (Cystophora cristata) and harp seals (Phoca Groenlandica)
Journal of comparative physiology. B Biochemical systemic and environmental physiology, 2000Co-Authors: I. Skalstad, Erling S. NordøyAbstract:This study was undertaken to measure whether young harp seals (Phoca Groenlandica) and hooded seals (Cystophora cristata) drink seawater and, if so, to investigate how the excess salt load is handled. Blood and urine samples were collected from hooded seal pups (n=3) and harp seal pups (n=3) after 2 weeks of freshwater exposure, at intervals during 3 weeks of seawater exposure and, finally, after 2 weeks of re-exposure to fresh water. Total water turnover, as measured by injection of tritiated water, was 2200 ml · day−1 and 3300 ml · day−1 in hooded seals and harp seals, respectively. The extent of mariposia was taken as the difference between total water turnover and influx of water through food (free and metabolic water) and respiratory water exchange. Seawater drinking amounted to 14% and 27% of total water turnover (rH2O) for the hooded seals and harp seals, respectively. Further evidence of mariposia was obtained from an increase in the excretion rate of the urine osmolytes Na+, Cl− and Mg2+, during the period of seawater exposure. It is concluded that water influx due to seawater drinking can not be excluded as a source of error when estimating food consumption of free-ranging harp seals and hooded seals, by use of labeled water techniques.
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metabolic adaptations to fasting in harp seal pups
Physiological and Biochemical Zoology, 1993Co-Authors: Erling S. Nordøy, Asbjorn Aakvaag, Terje S LarsenAbstract:Harp seal (Phoca Groenlandica) pups were studied during a 32-d postweaning fast. Body weight was reduced to 69% ± 0.8% (standard error of the mean [SEM]) of initial value during this period. The plasma level of glucose remained stable at 10.2 ± 0.3 (SEM) mM, while blood β-hydroxybutyrate and plasma free fatty acids (FFAs) increased by factors of 27 and 2.1 from initial levels of 0.06 ± 0.01 (SEM) mM and 1.44 ± 0.17 (SEM) mM, respectively. Repeated bolus injections of $^{14}C-oleate$ suggested replacement rates of FFAs on the order of 20-29 μ mol · kg⁻¹ · min⁻¹. The plasma levels of adrenaline, noradrenaline, T₃, and T₄ did not change significantly during the fasting period (P > 0.05), and plasma cortisol was maintained as low as 143 ± 9 (SEM) mM throughout the fast. Plasma aldosterone increased from 676 ± 239 (SEM) pM on day 2 to 6,821 ± 2,045 (SEM) pM on day 30 of fasting (P < 0. 01). Daily urine production decreased to only 6% of initial value between days 1 and 31, the principal end product, urea, acco...
Mike Hammill - One of the best experts on this subject based on the ideXlab platform.
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PBDEs in serum and blubber of harbor, grey and harp seal pups from Eastern Canada.
Chemosphere, 2011Co-Authors: Héloïse Frouin, Michel Lebeuf, Mike Hammill, Becky Sjare, Michel FournierAbstract: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.
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comparison of toxaphene congeners levels in five seal species from eastern canada what is the importance of biological factors
Environmental Science & Technology, 2005Co-Authors: Bruno Gouteux, Michel Lebeuf, Mike Hammill, Derek C G Muir, Jeanpierre GagneAbstract:Environmentally relevant chlorobornanes (CHBs) were measured in blubber samples of harbor (Phoca vitulina), gray (Halichoerus grypus), harp (Phoca Groenlandica), and hooded seals (Cystophora crista...
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inverse modelling of trophic flows through an entire ecosystem the northern gulf of st lawrence in the mid 1980s
Canadian Journal of Fisheries and Aquatic Sciences, 2004Co-Authors: Claude Savenkoff, Martin Castonguay, Alain F Vezina, Simonpierre Despatie, Denis Chabot, Lyne Morissette, Mike HammillAbstract:Mass-balance models using inverse methodology have been constructed for the northern Gulf of St. Lawrence ecosystem in the mid-1980s, before the groundfish collapse. The results highlight the effects of the major mortality sources (fishing, predation, and other sources of mortality) on the fish and invertebrate communities. Main predators of fish were large cod (Gadus morhua) followed by redfish (Sebastes spp.), capelin (Mallotus villosus), and fisheries. Large cod were the most important predator of small cod, with cannibalism accounting for at least 44% of the mortality of small cod. The main predators of large cod were harp (Phoca Groenlandica) and grey (Halichoerus grypus) seals. However, predation represented only 2% of total mortality on large cod. Mortality other than predation dominated the mortality processes at 52% of the total, while the fishery represented 46%. Tests were performed to identify possible sources of this unexplained mortality. The only way to significantly reduce unexplained mort...
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evaluation of body condition in the northwest atlantic harp seal Phoca Groenlandica
Canadian Journal of Fisheries and Aquatic Sciences, 1993Co-Authors: Gregor Gilpin Beck, Thomas G Smith, Mike HammillAbstract:We evaluated body condition in 315 harp seals (Phoca Groenlandica) obtained between 1988 and 1991. Total percent lipid of blubber did not vary between the five body sites and three depths sampled. In nine winter specimens, blubber, carcass, viscera, and skin contributed 89.5, 8.7, 0.9, and 0.9% of total body lipid. Pregnant females in winter had higher percent lipid in muscle than males, but no difference was observed in percent lipid in liver or blubber or in liver mass. Those females obtained 1 mo postpartum had the highest percent lipid in muscle and liver, the heaviest livers, but the lowest blubber lipid content. Sculp mass (skin with attached blubber) increased from autumn through late winter, with pregnant females having heavier sculps than males in winter. Both sculp and core mass varied on a seasonal and annual basis in males and females. Blubber was most variable dorsally between 40 and 70% of length, measured from the snout, and thickest at 50%, coincident with the position of maximum girth. Bl...