The Experts below are selected from a list of 867 Experts worldwide ranked by ideXlab platform
Lars P. Folkow - One of the best experts on this subject based on the ideXlab platform.
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cell culture experiments reveal that high s100b and clusterin levels may convey hypoxia tolerance to the Hooded Seal cystophora cristata brain
Neuroscience, 2020Co-Authors: Cornelia Gesner, Andrej Fabrizius, Lars P. Folkow, Maren Nicole Stillger, Naomi Molders, Thorsten BurmesterAbstract:While the brain of most mammals suffers from irreversible damage after only short periods of low oxygen levels (hypoxia), marine mammals are excellent breath-hold divers that have adapted to hypoxia. In addition to physiological adaptations, such as large oxygen storing capacity and strict oxygen economy during diving, the neurons of the deep-diving Hooded Seal (Cystophora cristata) have an intrinsic tolerance to hypoxia. We aim to understand the molecular basis of this neuronal hypoxia tolerance. Previously, transcriptomics of the cortex of the Hooded Seal have revealed remarkably high expression levels of S100B and clusterin (apolipoprotein J) when compared to the ferret, a non-diving carnivore. Both genes have much-debated roles in hypoxia and oxidative stress. Here, we evaluated the effects of S100B and of two isoforms of clusterin (soluble and nucleus clusterin) on the survival, metabolic activity and the amount of reactive oxygen species (ROS) in HN33 neuronal mouse cells exposed to hypoxia and oxidative stress. S100B and soluble clusterin had neuroprotective effects, with reduced ROS-levels and retention of normoxic energy status of cells during both stress conditions. The protective effects of nucleus clusterin were restricted to hypoxia. S100B and clusterin showed purifying selection in marine and terrestrial mammals, indicating a functional conservation across species. Immunofluorescence revealed identical cellular distributions of S100B and clusterin in mice, ferrets and Hooded Seals, further supporting the functional conservation. Taken together, our data suggest that the neuroprotective effects of all three proteins are exclusively facilitated by their increased expression in the brain of the Hooded Seal.
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Transcriptome Analysis Identifies Key Metabolic Changes in the Hooded Seal (Cystophora cristata) Brain in Response to Hypoxia and Reoxygenation.
PloS one, 2017Co-Authors: Mariana Leivas Müller Hoff, Andrej Fabrizius, Nicole U. Czech-damal, Lars P. Folkow, Thorsten BurmesterAbstract:The brain of diving mammals tolerates low oxygen conditions better than the brain of most terrestrial mammals. Previously, it has been demonstrated that the neurons in brain slices of the Hooded Seal (Cystophora cristata) withstand hypoxia longer than those of mouse, and also tolerate reduced glucose supply and high lactate concentrations. This tolerance appears to be accompanied by a shift in the oxidative energy metabolism to the astrocytes in the Seal while in terrestrial mammals the aerobic energy production mainly takes place in neurons. Here, we used RNA-Seq to compare the effect of hypoxia and reoxygenation in vitro on brain slices from the visual cortex of Hooded Seals. We saw no general reduction of gene expression, suggesting that the response to hypoxia and reoxygenation is an actively regulated process. The treatments caused the preferential upregulation of genes related to inflammation, as found before e.g. in stroke studies using mammalian models. Gene ontology and KEGG pathway analyses showed a downregulation of genes involved in ion transport and other neuronal processes, indicative for a neuronal shutdown in response to a shortage of O2 supply. These differences may be interpreted in terms of an energy saving strategy in the Seal's brain. We specifically analyzed the regulation of genes involved in energy metabolism. Hypoxia and reoxygenation caused a similar response, with upregulation of genes involved in glucose metabolism and downregulation of the components of the pyruvate dehydrogenase complex. We also observed upregulation of the monocarboxylate transporter Mct4, suggesting increased lactate efflux. Together, these data indicate that the Seal brain responds to the hypoxic challenge by a relative increase in the anaerobic energy metabolism.
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Summary of Illumina sequencing of the Hooded Seal brain transcriptomes.
2017Co-Authors: Mariana Leivas Müller Hoff, Andrej Fabrizius, Nicole U. Czech-damal, Lars P. Folkow, Thorsten BurmesterAbstract:Summary of Illumina sequencing of the Hooded Seal brain transcriptomes.
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Summary of the de novo assembly of the Hooded Seal brain transcriptomes.
2017Co-Authors: Mariana Leivas Müller Hoff, Andrej Fabrizius, Nicole U. Czech-damal, Lars P. Folkow, Thorsten BurmesterAbstract:Summary of the de novo assembly of the Hooded Seal brain transcriptomes.
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Gene ontology analyses of hypoxia and hypoxia/reoxygenation-regulated genes in Seal brain slices.
2017Co-Authors: Mariana Leivas Müller Hoff, Andrej Fabrizius, Nicole U. Czech-damal, Lars P. Folkow, Thorsten BurmesterAbstract:GO analysis in the domain "molecular function" of the significantly up- (A) and down- (B) regulated genes in the Hooded Seal brain slices after 1 h hypoxia (black) and after 1 h hypoxia followed by 20 min reoxygenation (white). The analyses of the GO terms in the categories "biological process" and "protein class" are given in S3 and S4 Figs.
Thorsten Burmester - One of the best experts on this subject based on the ideXlab platform.
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cell culture experiments reveal that high s100b and clusterin levels may convey hypoxia tolerance to the Hooded Seal cystophora cristata brain
Neuroscience, 2020Co-Authors: Cornelia Gesner, Andrej Fabrizius, Lars P. Folkow, Maren Nicole Stillger, Naomi Molders, Thorsten BurmesterAbstract:While the brain of most mammals suffers from irreversible damage after only short periods of low oxygen levels (hypoxia), marine mammals are excellent breath-hold divers that have adapted to hypoxia. In addition to physiological adaptations, such as large oxygen storing capacity and strict oxygen economy during diving, the neurons of the deep-diving Hooded Seal (Cystophora cristata) have an intrinsic tolerance to hypoxia. We aim to understand the molecular basis of this neuronal hypoxia tolerance. Previously, transcriptomics of the cortex of the Hooded Seal have revealed remarkably high expression levels of S100B and clusterin (apolipoprotein J) when compared to the ferret, a non-diving carnivore. Both genes have much-debated roles in hypoxia and oxidative stress. Here, we evaluated the effects of S100B and of two isoforms of clusterin (soluble and nucleus clusterin) on the survival, metabolic activity and the amount of reactive oxygen species (ROS) in HN33 neuronal mouse cells exposed to hypoxia and oxidative stress. S100B and soluble clusterin had neuroprotective effects, with reduced ROS-levels and retention of normoxic energy status of cells during both stress conditions. The protective effects of nucleus clusterin were restricted to hypoxia. S100B and clusterin showed purifying selection in marine and terrestrial mammals, indicating a functional conservation across species. Immunofluorescence revealed identical cellular distributions of S100B and clusterin in mice, ferrets and Hooded Seals, further supporting the functional conservation. Taken together, our data suggest that the neuroprotective effects of all three proteins are exclusively facilitated by their increased expression in the brain of the Hooded Seal.
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Transcriptome Analysis Identifies Key Metabolic Changes in the Hooded Seal (Cystophora cristata) Brain in Response to Hypoxia and Reoxygenation.
PloS one, 2017Co-Authors: Mariana Leivas Müller Hoff, Andrej Fabrizius, Nicole U. Czech-damal, Lars P. Folkow, Thorsten BurmesterAbstract:The brain of diving mammals tolerates low oxygen conditions better than the brain of most terrestrial mammals. Previously, it has been demonstrated that the neurons in brain slices of the Hooded Seal (Cystophora cristata) withstand hypoxia longer than those of mouse, and also tolerate reduced glucose supply and high lactate concentrations. This tolerance appears to be accompanied by a shift in the oxidative energy metabolism to the astrocytes in the Seal while in terrestrial mammals the aerobic energy production mainly takes place in neurons. Here, we used RNA-Seq to compare the effect of hypoxia and reoxygenation in vitro on brain slices from the visual cortex of Hooded Seals. We saw no general reduction of gene expression, suggesting that the response to hypoxia and reoxygenation is an actively regulated process. The treatments caused the preferential upregulation of genes related to inflammation, as found before e.g. in stroke studies using mammalian models. Gene ontology and KEGG pathway analyses showed a downregulation of genes involved in ion transport and other neuronal processes, indicative for a neuronal shutdown in response to a shortage of O2 supply. These differences may be interpreted in terms of an energy saving strategy in the Seal's brain. We specifically analyzed the regulation of genes involved in energy metabolism. Hypoxia and reoxygenation caused a similar response, with upregulation of genes involved in glucose metabolism and downregulation of the components of the pyruvate dehydrogenase complex. We also observed upregulation of the monocarboxylate transporter Mct4, suggesting increased lactate efflux. Together, these data indicate that the Seal brain responds to the hypoxic challenge by a relative increase in the anaerobic energy metabolism.
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Summary of Illumina sequencing of the Hooded Seal brain transcriptomes.
2017Co-Authors: Mariana Leivas Müller Hoff, Andrej Fabrizius, Nicole U. Czech-damal, Lars P. Folkow, Thorsten BurmesterAbstract:Summary of Illumina sequencing of the Hooded Seal brain transcriptomes.
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Summary of the de novo assembly of the Hooded Seal brain transcriptomes.
2017Co-Authors: Mariana Leivas Müller Hoff, Andrej Fabrizius, Nicole U. Czech-damal, Lars P. Folkow, Thorsten BurmesterAbstract:Summary of the de novo assembly of the Hooded Seal brain transcriptomes.
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Gene ontology analyses of hypoxia and hypoxia/reoxygenation-regulated genes in Seal brain slices.
2017Co-Authors: Mariana Leivas Müller Hoff, Andrej Fabrizius, Nicole U. Czech-damal, Lars P. Folkow, Thorsten BurmesterAbstract:GO analysis in the domain "molecular function" of the significantly up- (A) and down- (B) regulated genes in the Hooded Seal brain slices after 1 h hypoxia (black) and after 1 h hypoxia followed by 20 min reoxygenation (white). The analyses of the GO terms in the categories "biological process" and "protein class" are given in S3 and S4 Figs.
Kit M. Kovacs - One of the best experts on this subject based on the ideXlab platform.
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Effects of a complex contaminant mixture on thyroid hormones in breeding Hooded Seal mothers and their pups.
Environmental pollution (Barking Essex : 1987), 2018Co-Authors: Randi Grønnestad, Kit M. Kovacs, Christian Lydersen, Gro Dehli Villanger, Anuschka Polder, Bjørn Munro Jenssen, Katrine BorgåAbstract:Abstract There is a general lack of information on the possible effects of perfluoroalkyl substances (PFASs) on thyroid hormones (THs) in wildlife species. The effects of PFASs, which are known endocrine disruptors, on the TH homeostasis in Hooded Seals (Cystophora cristata) have yet to be investigated. Previously, correlations were found between plasma thyroid hormone (TH) concentrations in Hooded Seals, and organohalogen contaminants (OHCs) and hydroxyl (OH)-metabolites. Because animals are exposed to multiple contaminants simultaneously in nature, the effects of the complex contaminant mixtures that they accumulate should be assessed. Herein, we analyse relationships between plasma concentrations of multiple contaminants including protein-associated PFASs, hydroxylated metabolites of polychlorinated biphenyls (OH-PCBs) and lipid soluble OHCs and plasma concentrations of free and total THs, i.e. triiodothyronine (FT3, TT3) and thyroxine (FT4, TT4) in Hooded Seal mothers and their pups. The perfluoroalkyl carboxylates (PFCAs) were the most important predictors for FT3 concentrations and TT3:FT3 ratios in the mothers. The FT3 levels decreased with increasing PFCA levels, while the TT3:FT3 ratios increased. In the pups, hexachlorocyclohexanes (HCHs) were the most important predictors for TT3:FT3 ratios, increasing with increasing HCHs levels. Additionally, perfluoroalkyl sulfonates (PFSAs) and PFCAs were important predictors for FT4:FT3 ratios in Hooded Seal pups, and the ratio increased with increasing concentrations. The study suggests that PFASs contribute to thyroid disruption in Hooded Seals exposed to complex contaminant mixtures that include chlorinated and fluorinated organic compounds.
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Hooded Seal Cystophora cristata foraging areas in the Northeast Atlantic Ocean—Investigated using three complementary methods - Fig 1
2017Co-Authors: Jade Vacquie-garcia, Tore Haug, Christian Lydersen, Martin Biuw, Mike A. Fedak, Kit M. KovacsAbstract:Hooded Seal foraging trips during A) the post-breeding season and B) the post-molting season. Blue lines represent adult males, red lines represent adult females and purple lines represent the pups. The green dot represents the mean deployment point.
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Hooded Seal Cystophora cristata foraging areas in the Northeast Atlantic Ocean—Investigated using three complementary methods - Fig 2
2017Co-Authors: Jade Vacquie-garcia, Tore Haug, Christian Lydersen, Martin Biuw, Mike A. Fedak, Kit M. KovacsAbstract:Hooded Seal foraging index per day using A) first passage time (days), B), PCA-derived foraging intensity (based on combined vertical transit rates when diving (no unit)), and C) the change in drift rate (m/s). First passage time was calculated using a 55 km scale. For each graph—the warmer the colors, the higher the values.
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effects of complex organohalogen contaminant mixtures on thyroid homeostasis in Hooded Seal cystophora cristata mother pup pairs
Chemosphere, 2013Co-Authors: Gro Dehli Villanger, Kit M. Kovacs, Elisabeth Lie, Christian Lydersen, Kristin Møller Gabrielsen, Mahin Karimi, Eugen G. Sørmo, Bjørn Munro JenssenAbstract:Many lipid-soluble and phenolic compounds present in the complex mixture of orgaohalogen contaminants (OHCs) that arctic wildlife is exposed to have the ability to interfere with the thyroid hormone (TH) system. The aim of this study was to identify compounds that might interfere with thyroid homeostasis in 14 nursing Hooded Seal (Cystophora cristata) mothers and their pups (1–4 d old) sampled in the West Ice in March 2008. Multivariate modelling was used to assess the potential effects of measured plasma levels of OHCs on circulating TH levels of the measured free (F) and total (T) levels of triidothyrine (T3) and thyroxine (T4). Biological factors were important in all models (e.g. age and sex). In both mothers and pups, TT3:FT3 ratios were associated with a- and b-hexachlorocyclohexane (HCH), ortho-PCBs, chlordanes and DDTs. The similarities between the modelled TT3:FT3 responses to OHC levels in Hooded Seal mothers and pups most probably reflects similar exposure patterns, but could also indicate interconnected TH responses. There were some differences in the modelled TH responses of mothers and pups. Most importantly, the negative relationships between many OH-PCBs (particularly 3’-OH-CB138) and TT3:FT3 ratio and the positive relationships between TT4:FT4 ratios and polybrominated diphenyl ether [PBDE]-99, -100 and 4-OH-CB107 in pups, which was not found in mothers. Although statistical associations are not evidence per se of biological cause–effect relationships, the results suggest that thyroid homeostasis is affected in Hooded Seals, and that the inclusion of the fullest possible OHC mixture is important when assessing TH related effects in wildlife.
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Effects of complex organohalogen contaminant mixtures on thyroid homeostasis in Hooded Seal (Cystophora cristata) mother–pup pairs
Chemosphere, 2013Co-Authors: Gro Dehli Villanger, Kit M. Kovacs, Elisabeth Lie, Christian Lydersen, Kristin Møller Gabrielsen, Mahin Karimi, Eugen G. Sørmo, Bjørn Munro JenssenAbstract:Many lipid-soluble and phenolic compounds present in the complex mixture of orgaohalogen contaminants (OHCs) that arctic wildlife is exposed to have the ability to interfere with the thyroid hormone (TH) system. The aim of this study was to identify compounds that might interfere with thyroid homeostasis in 14 nursing Hooded Seal (Cystophora cristata) mothers and their pups (1–4 d old) sampled in the West Ice in March 2008. Multivariate modelling was used to assess the potential effects of measured plasma levels of OHCs on circulating TH levels of the measured free (F) and total (T) levels of triidothyrine (T3) and thyroxine (T4). Biological factors were important in all models (e.g. age and sex). In both mothers and pups, TT3:FT3 ratios were associated with a- and b-hexachlorocyclohexane (HCH), ortho-PCBs, chlordanes and DDTs. The similarities between the modelled TT3:FT3 responses to OHC levels in Hooded Seal mothers and pups most probably reflects similar exposure patterns, but could also indicate interconnected TH responses. There were some differences in the modelled TH responses of mothers and pups. Most importantly, the negative relationships between many OH-PCBs (particularly 3’-OH-CB138) and TT3:FT3 ratio and the positive relationships between TT4:FT4 ratios and polybrominated diphenyl ether [PBDE]-99, -100 and 4-OH-CB107 in pups, which was not found in mothers. Although statistical associations are not evidence per se of biological cause–effect relationships, the results suggest that thyroid homeostasis is affected in Hooded Seals, and that the inclusion of the fullest possible OHC mixture is important when assessing TH related effects in wildlife.
Jacques Godfroid - One of the best experts on this subject based on the ideXlab platform.
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Entry and Elimination of Marine Mammal Brucella spp. by Hooded Seal (Cystophora cristata) Alveolar Macrophages In Vitro
2016Co-Authors: Anett K. Larsen, Ingebjorg Helena Nymo, Preben Boysen, Morten Tryl, Jacques GodfroidAbstract:A high prevalence of Brucella pinnipedialis serology and bacteriology positive animals has been found in the Northeast Atlantic stock of Hooded Seal (Cystophora cristata); however no associated gross pathological changes have been identified. Marine mammal brucellae have previously displayed different infection patterns in human and murine macrophages. To investigate if marine mammal Brucella spp. are able to invade and multiply in cells originating from a presumed host species, we infected alveolar macrophages from Hooded Seal with a B. pinnipedialis Hooded Seal isolate. Hooded Seal alveolar macrophages were also challenged with B. pinnipedialis reference strain (NCTC 12890) from harbor Seal (Phoca vitulina), B. ceti reference strain (NCTC 12891) from harbor porpoise (Phocoena phocoena) and a B. ceti Atlantic white-sided dolphin (Lagenorhynchus acutus) isolate (M83/07/1), to evaluate possible species-specific differences. Brucella suis 1330 was included as a positive control. Alveolar macrophages were obtained by post mortem bronchoalveolar lavage of euthanized Hooded Seals. Phenotyping of cells in the lavage fluid was executed by flow cytometry using the surface markers CD14 and CD18. Cultured lavage cells were identified as alveolar macrophages based on morphology, expression of surface markers and phagocytic ability. Alveolar macrophages were challenged with Brucella spp. in a gentamicin protection assay. Following infection, cell lysates from different time points were plated and evaluated quantitatively for colony formin
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Experimental Challenge of Atlantic Cod (Gadus morhua) with a Brucella pinnipedialis Strain from Hooded Seal (Cystophora cristata).
PloS one, 2016Co-Authors: Ingebjorg Helena Nymo, Jacques Godfroid, Marit Seppola, Al Dahouk Sascha, Katrine Ryvold Arnesen Bakkemo, María Pilar Jiménez De Bagüés, Anett Kristin LarsenAbstract:Pathology has not been observed in true Seals infected with Brucella pinnipedialis. A lack of intracellular survival and multiplication of B. pinnipedialis in Hooded Seal (Cystophora cristata) macrophages in vitro indicates a lack of chronic infection in Hooded Seals. Both epidemiology and bacteriological patterns in the Hooded Seal point to a transient infection of environmental origin, possibly through the food chain. To analyse the potential role of fish in the transmission of B. pinnipedialis, Atlantic cod (Gadus morhua) were injected intraperitoneally with 7.5 x 107 bacteria of a Hooded Seal field isolate. Samples of blood, liver, spleen, muscle, heart, head kidney, female gonads and feces were collected on days 1, 7, 14 and 28 post infection to assess the bacterial load, and to determine the expression of immune genes and the specific antibody response. Challenged fish showed an extended period of bacteremia through day 14 and viable bacteria were observed in all organs sampled, except muscle, until day 28. Neither gross lesions nor mortality were recorded. Anti-Brucella antibodies were detected from day 14 onwards and the expression of hepcidin, cathelicidin, interleukin (IL)-1β, IL-10, and interferon (IFN)-γ genes were significantly increased in spleen at day 1 and 28. Primary mononuclear cells isolated from head kidneys of Atlantic cod were exposed to B. pinnipedialis reference (NCTC 12890) and Hooded Seal (17a-1) strain. Both bacterial strains invaded mononuclear cells and survived intracellularly without any major reduction in bacterial counts for at least 48 hours. Our study shows that the B. pinnipedialis strain isolated from Hooded Seal survives in Atlantic cod, and suggests that Atlantic cod could play a role in the transmission of B. pinnipedialis to Hooded Seals in the wild.
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Brucella pinnipedialis in Hooded Seal (Cystophora cristata) primary epithelial cells
Acta veterinaria Scandinavica, 2016Co-Authors: Anett Kristin Larsen, Jacques Godfroid, Ingebjorg Helena NymoAbstract:Background Marine Brucella spp. have been isolated from numerous pinniped and cetacean species, but pathological findings in association with infection with Brucella pinnipedialis in pinnipeds have been sparse. The capacity of brucellae to survive and replicate within host macrophages underlies their important ability to produce chronic infections, but previous work has shown that B. pinnipedialis spp. are rapidly eliminated from Hooded Seal (Cystophora cristata) alveolar macrophages.
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Brucella pinnipedialis survives in Atlantic cod head kidney derived monocytes/macrophages (HKDM).
2016Co-Authors: Ingebjorg Helena Nymo, Jacques Godfroid, Marit Seppola, María Pilar Jiménez De Bagüés, Sascha, Al Dahouk, Kathrine Ryvold Bakkemo, Anett Kristin LarsenAbstract:Intracellular survival of B. pinnipedialis Hooded Seal strain 17a-1 (A) and B. pinnipedialis reference strain 12890 (B) in HKDM at 1.5, 24, and 48 h post infection. Results from each fish are depicted individually and each time point represents the mean of 2 wells ± standard deviation.
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Atlantic cod infected with Brucella pinnipedialis mounts a specific antibody response.
2016Co-Authors: Ingebjorg Helena Nymo, Jacques Godfroid, Marit Seppola, María Pilar Jiménez De Bagüés, Sascha, Al Dahouk, Kathrine Ryvold Bakkemo, Anett Kristin LarsenAbstract:Level of anti-Brucella antibodies, as measured by an ELISA, in Atlantic cod after intraperitoneal injection of 7.5 x 107 CFU of B. pinnipedialis Hooded Seal strain 17a-1 (dark grey) or sterile PBS (light grey) on days 1, 7, 14 and 28 post infection. Each bar shows the mean ± standard deviation of n = 4–6 fish. (*) Significantly different from non-infected controls (p < 0.05 was considered significant).
Christian Lydersen - One of the best experts on this subject based on the ideXlab platform.
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Effects of a complex contaminant mixture on thyroid hormones in breeding Hooded Seal mothers and their pups.
Environmental pollution (Barking Essex : 1987), 2018Co-Authors: Randi Grønnestad, Kit M. Kovacs, Christian Lydersen, Gro Dehli Villanger, Anuschka Polder, Bjørn Munro Jenssen, Katrine BorgåAbstract:Abstract There is a general lack of information on the possible effects of perfluoroalkyl substances (PFASs) on thyroid hormones (THs) in wildlife species. The effects of PFASs, which are known endocrine disruptors, on the TH homeostasis in Hooded Seals (Cystophora cristata) have yet to be investigated. Previously, correlations were found between plasma thyroid hormone (TH) concentrations in Hooded Seals, and organohalogen contaminants (OHCs) and hydroxyl (OH)-metabolites. Because animals are exposed to multiple contaminants simultaneously in nature, the effects of the complex contaminant mixtures that they accumulate should be assessed. Herein, we analyse relationships between plasma concentrations of multiple contaminants including protein-associated PFASs, hydroxylated metabolites of polychlorinated biphenyls (OH-PCBs) and lipid soluble OHCs and plasma concentrations of free and total THs, i.e. triiodothyronine (FT3, TT3) and thyroxine (FT4, TT4) in Hooded Seal mothers and their pups. The perfluoroalkyl carboxylates (PFCAs) were the most important predictors for FT3 concentrations and TT3:FT3 ratios in the mothers. The FT3 levels decreased with increasing PFCA levels, while the TT3:FT3 ratios increased. In the pups, hexachlorocyclohexanes (HCHs) were the most important predictors for TT3:FT3 ratios, increasing with increasing HCHs levels. Additionally, perfluoroalkyl sulfonates (PFSAs) and PFCAs were important predictors for FT4:FT3 ratios in Hooded Seal pups, and the ratio increased with increasing concentrations. The study suggests that PFASs contribute to thyroid disruption in Hooded Seals exposed to complex contaminant mixtures that include chlorinated and fluorinated organic compounds.
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Hooded Seal Cystophora cristata foraging areas in the Northeast Atlantic Ocean—Investigated using three complementary methods - Fig 1
2017Co-Authors: Jade Vacquie-garcia, Tore Haug, Christian Lydersen, Martin Biuw, Mike A. Fedak, Kit M. KovacsAbstract:Hooded Seal foraging trips during A) the post-breeding season and B) the post-molting season. Blue lines represent adult males, red lines represent adult females and purple lines represent the pups. The green dot represents the mean deployment point.
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Hooded Seal Cystophora cristata foraging areas in the Northeast Atlantic Ocean—Investigated using three complementary methods - Fig 2
2017Co-Authors: Jade Vacquie-garcia, Tore Haug, Christian Lydersen, Martin Biuw, Mike A. Fedak, Kit M. KovacsAbstract:Hooded Seal foraging index per day using A) first passage time (days), B), PCA-derived foraging intensity (based on combined vertical transit rates when diving (no unit)), and C) the change in drift rate (m/s). First passage time was calculated using a 55 km scale. For each graph—the warmer the colors, the higher the values.
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effects of complex organohalogen contaminant mixtures on thyroid homeostasis in Hooded Seal cystophora cristata mother pup pairs
Chemosphere, 2013Co-Authors: Gro Dehli Villanger, Kit M. Kovacs, Elisabeth Lie, Christian Lydersen, Kristin Møller Gabrielsen, Mahin Karimi, Eugen G. Sørmo, Bjørn Munro JenssenAbstract:Many lipid-soluble and phenolic compounds present in the complex mixture of orgaohalogen contaminants (OHCs) that arctic wildlife is exposed to have the ability to interfere with the thyroid hormone (TH) system. The aim of this study was to identify compounds that might interfere with thyroid homeostasis in 14 nursing Hooded Seal (Cystophora cristata) mothers and their pups (1–4 d old) sampled in the West Ice in March 2008. Multivariate modelling was used to assess the potential effects of measured plasma levels of OHCs on circulating TH levels of the measured free (F) and total (T) levels of triidothyrine (T3) and thyroxine (T4). Biological factors were important in all models (e.g. age and sex). In both mothers and pups, TT3:FT3 ratios were associated with a- and b-hexachlorocyclohexane (HCH), ortho-PCBs, chlordanes and DDTs. The similarities between the modelled TT3:FT3 responses to OHC levels in Hooded Seal mothers and pups most probably reflects similar exposure patterns, but could also indicate interconnected TH responses. There were some differences in the modelled TH responses of mothers and pups. Most importantly, the negative relationships between many OH-PCBs (particularly 3’-OH-CB138) and TT3:FT3 ratio and the positive relationships between TT4:FT4 ratios and polybrominated diphenyl ether [PBDE]-99, -100 and 4-OH-CB107 in pups, which was not found in mothers. Although statistical associations are not evidence per se of biological cause–effect relationships, the results suggest that thyroid homeostasis is affected in Hooded Seals, and that the inclusion of the fullest possible OHC mixture is important when assessing TH related effects in wildlife.
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Effects of complex organohalogen contaminant mixtures on thyroid homeostasis in Hooded Seal (Cystophora cristata) mother–pup pairs
Chemosphere, 2013Co-Authors: Gro Dehli Villanger, Kit M. Kovacs, Elisabeth Lie, Christian Lydersen, Kristin Møller Gabrielsen, Mahin Karimi, Eugen G. Sørmo, Bjørn Munro JenssenAbstract:Many lipid-soluble and phenolic compounds present in the complex mixture of orgaohalogen contaminants (OHCs) that arctic wildlife is exposed to have the ability to interfere with the thyroid hormone (TH) system. The aim of this study was to identify compounds that might interfere with thyroid homeostasis in 14 nursing Hooded Seal (Cystophora cristata) mothers and their pups (1–4 d old) sampled in the West Ice in March 2008. Multivariate modelling was used to assess the potential effects of measured plasma levels of OHCs on circulating TH levels of the measured free (F) and total (T) levels of triidothyrine (T3) and thyroxine (T4). Biological factors were important in all models (e.g. age and sex). In both mothers and pups, TT3:FT3 ratios were associated with a- and b-hexachlorocyclohexane (HCH), ortho-PCBs, chlordanes and DDTs. The similarities between the modelled TT3:FT3 responses to OHC levels in Hooded Seal mothers and pups most probably reflects similar exposure patterns, but could also indicate interconnected TH responses. There were some differences in the modelled TH responses of mothers and pups. Most importantly, the negative relationships between many OH-PCBs (particularly 3’-OH-CB138) and TT3:FT3 ratio and the positive relationships between TT4:FT4 ratios and polybrominated diphenyl ether [PBDE]-99, -100 and 4-OH-CB107 in pups, which was not found in mothers. Although statistical associations are not evidence per se of biological cause–effect relationships, the results suggest that thyroid homeostasis is affected in Hooded Seals, and that the inclusion of the fullest possible OHC mixture is important when assessing TH related effects in wildlife.
