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6TH NORWEGIAN ENVIRONMENTAL TOXICOLOGY SYMPOSIUM: Assessing and solving environmental challenges in a multiple stressor world.

https://arctichealth.org/en/permalink/ahliterature296704
Source
J Toxicol Environ Health A. 2017; 80(16-18):805-806
Publication Type
Introductory Journal Article
Date
2017
Author
Knut Erik Tollefsen
Sam Kacew
Author Affiliation
a Section for Ecotoxicology and Risk Assessment, Norwegian Institute for Water Research (NIVA) , Oslo , Norway.
Source
J Toxicol Environ Health A. 2017; 80(16-18):805-806
Date
2017
Language
English
Publication Type
Introductory Journal Article
Keywords
Ecotoxicology
Environmental Exposure
Environmental Monitoring - methods
Environmental Pollutants - toxicity
Norway
Risk Assessment - methods
PubMed ID
28829685 View in PubMed
Less detail

Characterization of AhR agonists reveals antagonistic activity in European herring gull (Larus argentatus) eggs.

https://arctichealth.org/en/permalink/ahliterature264577
Source
Sci Total Environ. 2015 May 1;514:211-8
Publication Type
Article
Date
May-1-2015
Author
Martine Muusse
Guttorm Christensen
Tânia Gomes
Anton Kocan
Katherine Langford
Knut Erik Tollefsen
Lenka Vanková
Kevin V Thomas
Source
Sci Total Environ. 2015 May 1;514:211-8
Date
May-1-2015
Language
English
Publication Type
Article
Keywords
Animals
Biological Markers - metabolism
Charadriiformes - metabolism
Dioxins - analysis - metabolism
Eggs
Environmental Monitoring - methods
Environmental Pollutants - analysis - metabolism
Norway
Ovum - chemistry - metabolism
Receptors, Aryl Hydrocarbon - metabolism
Abstract
European herring gull (Larus argentatus) eggs from two Norwegian islands, Musvær in the south east and Reiaren in Northern Norway, were screened for dioxins, furans, and dioxin-like and selected non-dioxin-like polychlorinated biphenyls (PCBs), and subjected to non-target analysis to try to identify the aryl hydrocarbon receptor (AhR) agonists, responsible for elevated levels measured using the dioxin responsive chemically activated luciferase expression (DR-CALUX) assay. Eggs from Musvær contained chemically calculated toxic equivalent (WHO TEQ) levels of between 109 and 483 pg TEQ/g lw, and between 82 and 337 pg TEQ/g lw was determined in eggs from Reiaren. In particular PCB126 contributed highly to the total TEQ (69-82%). In 19 of the 23 samples the calculated WHO TEQ was higher than the TEQCALUX. Using CALUX specific relative effect potencies (REPs), the levels were lower at between 77 and 292 pg/g lw in eggs from Musvær and between 55 and 223 pg/g lw in eggs from Reiaren, which was higher than the TEQCALUX in 16 of the 23 samples. However, the means of the REP values and the TEQCALUX were not significantly different. This suggests the presence of compounds that can elicit antagonist effects, with a low binding affinity to the AhR. Non-target analysis identified the presence of hexachlorobenzene (HCB) (quantified at 9.6-185 pg/g lw) but neither this compound nor high concentrations of PCB126 and non-dioxin-like PCBs could explain the differences between the calculated TEQ or REP values and the TEQCALUX. Even though, for most AhR agonists, the sensitivity of herring gulls is not known, the reported levels can be considered to represent a risk for biological effects in the developing embryo, compared to LC50 values in chicken embryos. For human consumers of herring gull eggs, these eggs contain TEQ levels up to four times higher than the maximum tolerable weekly intake.
PubMed ID
25666281 View in PubMed
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Characterizing cytotoxic and estrogenic activity of Arctic char tissue extracts in primary Arctic char hepatocytes.

https://arctichealth.org/en/permalink/ahliterature285288
Source
J Toxicol Environ Health A. 2017 Sep 01;:1-14
Publication Type
Article
Date
Sep-01-2017
Author
Karina Petersen
Maria T Hultman
Jenny Bytingsvik
Mikael Harju
Anita Evenset
Knut Erik Tollefsen
Source
J Toxicol Environ Health A. 2017 Sep 01;:1-14
Date
Sep-01-2017
Language
English
Publication Type
Article
Abstract
Contaminants from various anthropogenic activities are detected in the Arctic due to long-range atmospheric transport, ocean currents, and living organisms such as migrating fish or seabirds. Although levels of persistent organic pollutants (POPs) in Arctic fish are generally low, local hot spots of contamination were found in freshwater systems such as Lake Ellasjøen at Bjørnøya (Bear Island, Norway). Higher concentrations of organic halogenated compounds (OHC), and higher levels of cytochrome P450 and DNA-double strand breaks were reported in Arctic char (Salvelinus alpinus) from this lake compared to fish from other lakes on Bjørnøya. Although several of the measured contaminants are potential endocrine disrupters, few studies have investigated potential endocrine disruptive effects of the contaminant cocktail in this fish population. The aim of this study was to compare acutely toxic and estrogenic potency of the cocktail of pollutants as evidenced by cytotoxic and/or estrogenic effects in vitro using extracts of Arctic char livers from contaminated Lake Ellasjøen with those from less contaminated Lake Laksvatn at Bjørnøya. This was performed by in situ sampling and contaminant extraction from liver tissue, followed by chemical analysis and in vitro testing of the following contaminated tissue extracts: F1-nonpolar OHC, F2-polar pesticides and metabolites of OHC, and F3-polar OHC. Contaminant levels were highest in extracts from Ellasjøen fish. The F2 and F3 extracts from Lake Laksvatn and Lake Ellasjøen fish reduced in vitro cell viability at a concentration ratio of 0.03-1 relative to tissue concentration in Arctic char. Only the F3 liver extract from Ellasjøen fish increased in vitro vitellogenin protein expression. Although compounds such as estrogenic OH-PCBs were quantified in Ellasjøen F3 extracts, it remains to be determined which compounds were inducing estrogenic effects.
PubMed ID
28862540 View in PubMed
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Effects of chronic dietary petroleum exposure on reproductive development in polar cod (Boreogadus saida).

https://arctichealth.org/en/permalink/ahliterature276916
Source
Aquat Toxicol. 2016 Oct 4;180:196-208
Publication Type
Article
Date
Oct-4-2016
Author
Morgan Lizabeth Bender
Marianne Frantzen
Ireen Vieweg
Inger-Britt Falk-Petersen
Helge Kreutzer Johnsen
Geir Rudolfsen
Knut Erik Tollefsen
Paul Dubourg
Jasmine Nahrgang
Source
Aquat Toxicol. 2016 Oct 4;180:196-208
Date
Oct-4-2016
Language
English
Publication Type
Article
Abstract
Increasing human activities in the Arctic raise the risk of petroleum pollution, thus posing an elevated risk for Arctic organisms to be chronically exposed to petroleum compounds. The endocrine disrupting properties of some of these compounds (i.e. polycyclic aromatic hydrocarbons [PAHs]) present in crude oil may have negative effects on the long and energy intensive reproductive development of polar cod (Boreogadus saida), an Arctic keystone species. In the present study, selected reproductive parameters were examined in feral polar cod exposed to crude oil via a natural diet (0.11, 0.57 and 1.14µg crude oil/g fish/day [corresponding to low, medium and high treatments, respectively]) for 31 weeks prior to spawning. Fish maturing in the current reproductive period made up 92% of the experimental population while 5% were immature and 3% were identified as resting fish. Phase I metabolism of PAHs, indicated by ethoxyresorufin-O-deethylase (EROD) activity, showed a dose-dependent increase in high and medium crude oil treatments at week 6 and 22, respectively. Decreasing EROD activity and increasing PAH bile metabolite concentrations over the experimental period may be explained by reproductive maturity stage. Significant alterations in sperm motility were observed in crude oil exposed males compared to the controls. The investigated somatic indices (gonad and hepatic), germ cell development and plasma steroid levels (estradiol-17ß [females], testosterone [males and females] and 11-ketotestosterone [males]) were not significantly altered by chronic dietary exposure to crude oil. The environmentally realistic doses polar cod were chronically exposed to in this study were likely not high enough to induce adverse effects in this ecologically important fish species. This study elucidated many baseline aspects of polar cod reproductive physiology and emphasized the influence of maturation state on biomarkers of PAH biotransformation (EROD and PAH bile metabolites).
PubMed ID
27723571 View in PubMed
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Individual and molecular level effects of produced water contaminants on nauplii and adult females of Calanus finmarchicus.

https://arctichealth.org/en/permalink/ahliterature274892
Source
J Toxicol Environ Health A. 2016;79(13-15):585-601
Publication Type
Article
Date
2016
Author
Louise Kiel Jensen
Elisabeth Halvorsen
You Song
Ingeborg G Hallanger
Elisabeth Lindbo Hansen
Steven J Brooks
Bjørn Henrik Hansen
Knut Erik Tollefsen
Source
J Toxicol Environ Health A. 2016;79(13-15):585-601
Date
2016
Language
English
Publication Type
Article
Abstract
In the Barents Sea region new petroleum fields are discovered yearly and extraction of petroleum products is expected to increase in the upcoming years. Despite enhanced technology and stricter governmental legislation, establishment of the petroleum industry in the Barents Sea may potentially introduce a new source of contamination to the area, as some discharges of produced water will be allowed. Whether the presence of produced water poses a risk to the Arctic marine life remains to be investigated. The aim of this study was to examine effects of exposure to several compounds found in produced water-a mixture of selected organic compounds (APW), radium-226 ((226)Ra), barium (Ba), and a scale inhibitor-on the copepod species Calanus finmarchicus. Experiments were performed using exposure concentrations at realistic levels based on those detected in the vicinity of known discharge points. The influence of lethal and sublethal effects on early life stages was determined and significantly lower survival in the APW exposure groups was found. In the Ba treatment the life stage development did not proceed to the same advanced stages as observed in the control (filtered sea water). The scale inhibitor and (226)Ra treatments showed no significant difference from control. In addition, adult females were exposed to APW, (226)Ra, and a mixture of the two. Both individual-level effects (egg production and feeding) and molecular-level effects (gene expression) were assessed. On the individual level endpoints, only treatments including APW produced an effect compared to control. However, on the molecular level the possibility that also (226)Ra induced toxicologically relevant effects cannot be ruled out.
PubMed ID
27484140 View in PubMed
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Miniaturization of a transthyretin binding assay using a fluorescent probe for high throughput screening of thyroid hormone disruption in environmental samples.

https://arctichealth.org/en/permalink/ahliterature282240
Source
Chemosphere. 2017 Mar;171:722-728
Publication Type
Article
Date
Mar-2017
Author
Xiyu Ouyang
Jean Froment
Pim E G Leonards
Guttorm Christensen
Knut-Erik Tollefsen
Jacob de Boer
Kevin V Thomas
Marja H Lamoree
Source
Chemosphere. 2017 Mar;171:722-728
Date
Mar-2017
Language
English
Publication Type
Article
Keywords
Animals
Biological Assay
Charadriiformes
Fluorescent Dyes
Miniaturization
Norway
Prealbumin - metabolism
Thyroxine - metabolism
Zygote
Abstract
Thyroid hormone (TH) disrupting compounds are potentially important environmental contaminants due to their possible adverse neurological and developmental effects on both humans and wildlife. Currently, the most successful bio-analytical method to detect and evaluate TH disruptors, which target the plasma transport of TH in environmental samples, is the radio-ligand thyroxine-transthyretin (T4-TTR) binding assay. Yet, costly materials and tedious handling procedures prevent the use of this assay in high throughput analysis that is nowadays urgently demanded in environmental quality assessment. For the first time a miniaturized fluorescence T4-TTR binding assay was developed in a 96 well microplate and tested with eight TH disrupting compounds. For most of the compounds, the sensitivity of the newly developed assay was slightly lower than the radio-ligand binding assay, however, throughput was enhanced at least 100-fold, while using much cheaper materials. The TH disrupting potency of 22 herring gull (Larus argentatus) egg extracts, collected from two different locations (Musvær and Reiaren) in Norway, was evaluated to demonstrate the applicability of the assay for environmental samples.
PubMed ID
28063299 View in PubMed
Less detail

Primary hepatocytes from Arctic char (Salvelinus alpinus) as a relevant Arctic in vitro model for screening contaminants and environmental extracts.

https://arctichealth.org/en/permalink/ahliterature281820
Source
Aquat Toxicol. 2017 Jun;187:141-152
Publication Type
Article
Date
Jun-2017
Author
Karina Petersen
Maria T Hultman
Knut Erik Tollefsen
Source
Aquat Toxicol. 2017 Jun;187:141-152
Date
Jun-2017
Language
English
Publication Type
Article
Abstract
Contaminants find their way to the Arctic through long-range atmospheric transport, transport via ocean currents, and through increased anthropogenic activity. Some of the typical pollutants reaching the Arctic (PAHs, PCBs) are known to induce cytochrome P450 1a (CYP1A) protein expression and ethoxyresorufin-O-deethylase (EROD) activity through the aryl hydrocarbon receptor (AhR). In addition, some endocrine disrupting chemicals (EDCs) such as estrogen mimics (xenoestrogens) have been documented in Arctic areas and they may interfere with natural sexual development and reproduction. In vitro assays that are capable of detecting effects of such pollutants, covering multiple endpoints, are generally based on mammalian or temperate species and there are currently no well-characterized cell-based in vitro assays for effect assessment from Arctic fish species. The present study aimed to develop a high-throughput and multi-endpoint in vitro assay from Arctic char (Salvelinus alpinus) to provide a non-animal (alternative) testing method for an ecologically relevant Arctic species. A method for isolation and exposure of primary hepatocytes from Arctic char for studying the toxic effects and mode of action (MoA) of pollutants was applied and validated. The multi-versatility of the bioassay was assessed by classical biomarker responses such as cell viability (membrane integrity and metabolic activity), phase I detoxification (CYP1A protein expression, EROD activity) and estrogen receptor (ER) mediated vitellogenin (Vtg) protein expression using a selection of model compounds, environmental pollutants and an environmental extract containing a complex mixture of pollutants. Primary hepatocytes from Arctic char were successfully isolated and culture conditions optimized to identify the most optimal assay conditions for covering multiple endpoints. The hepatocytes responded with concentration-dependent responses to all of the model compounds, most of the environmental pollutants and the environmental sample tested. The bioassay response and sensitivity of the hepatocytes from Arctic char differed slightly from closely related salmonid species, thus highlighting the need for developing in vitro assays relevant for Arctic species. The present multi-endpoint in vitro assay offer a highly versatile tool to screen potential effects of pollutants and complex samples relevant for Arctic exposure scenarios.
PubMed ID
28411469 View in PubMed
Less detail

Transcriptomic analysis reveals dose-dependent modes of action of benzo(a)pyrene in polar cod (Boreogadus saida).

https://arctichealth.org/en/permalink/ahliterature298561
Source
Sci Total Environ. 2019 Feb 25; 653:176-189
Publication Type
Journal Article
Date
Feb-25-2019
Author
You Song
Jasmine Nahrgang
Knut Erik Tollefsen
Author Affiliation
Norwegian Institute for Water Research (NIVA), Section of Ecotoxicology and Risk Assessment, Gaustadalléen 21, N-0349 Oslo, Norway. Electronic address: yso@niva.no.
Source
Sci Total Environ. 2019 Feb 25; 653:176-189
Date
Feb-25-2019
Language
English
Publication Type
Journal Article
Keywords
Animals
Arctic Regions
Benzo(a)pyrene - metabolism
Bile - chemistry
Biotransformation
Dose-Response Relationship, Drug
Environmental Exposure - adverse effects
Female
Gadiformes - genetics - metabolism
Gene Expression Profiling
Male
Oligonucleotide Array Sequence Analysis
Svalbard
Transcriptome - drug effects
Water Pollutants, Chemical - metabolism
Abstract
Polar cod (Boreogadus saida) has been used as a model Arctic species for hazard assessment of environmental stressors such as polycyclic aromatic hydrocarbons (PAHs). However, most of the PAH studies using polar cod rely on targeted biomarker-based analysis thus may not adequately address the complexity of the toxic mechanisms of the stressors. The present study was performed to develop a broad-content transcriptomic platform for polar cod and apply it for understanding the toxic mechanisms of a model PAH, benzo(a)pyrene (BaP). Hepatic transcriptional analysis using a combination of high-density polar cod oligonucleotide microarray and quantitative real-time RT-PCR was conducted to characterize the stress responses in polar cod after 14d repeated dietary exposure to 0.4 (Low) and 20.3?µg/g fish/feeding (High) BaP doses. Bile metabolic analysis was performed to identify the storage of a key BaP hepatic biotransformation product, 3-hydroxybenzo(a)pyrene (3-OH-BaP). The results clearly showed that 3-OH-BaP was detected in the bile of polar cod after both Low and High BaP exposure. Dose-dependent hepatic stress responses were identified, with Low BaP suppressing genes involved in the defense mechanisms and High BaP inducing genes associated with these pathways. The results suggested that activation of the aryl hydrocarbon receptor signaling, induction of oxidative stress, DNA damage and apoptosis were the common modes of action (MoA) of BaP between polar cod or other vertebrates, whereas induction of protein degradation and disturbance of mitochondrial functions were proposed as novel MoAs. Furthermore, conceptual toxicity pathways were proposed for BaP-mediated effects in Arctic fish. The present study has for the first time reported a transcriptome-wide analysis using a polar cod-specific microarray and suggested novel MoAs of BaP. The analytical tools, bioinformatics solutions and mechanistic knowledge generated by this study may facilitate mechanistically-based hazard assessment of environmental stressors in the Arctic using this important fish as a model species.
PubMed ID
30408666 View in PubMed
Less detail

Transcriptomic analysis reveals dose-dependent modes of action of benzo(a)pyrene in polar cod (Boreogadus saida).

https://arctichealth.org/en/permalink/ahliterature295787
Source
Sci Total Environ. 2018 Oct 21; 653:176-189
Publication Type
Journal Article
Date
Oct-21-2018
Author
You Song
Jasmine Nahrgang
Knut Erik Tollefsen
Author Affiliation
Norwegian Institute for Water Research (NIVA), Section of Ecotoxicology and Risk Assessment, Gaustadalléen 21, N-0349 Oslo, Norway. Electronic address: yso@niva.no.
Source
Sci Total Environ. 2018 Oct 21; 653:176-189
Date
Oct-21-2018
Language
English
Publication Type
Journal Article
Abstract
Polar cod (Boreogadus saida) has been used as a model Arctic species for hazard assessment of environmental stressors such as polycyclic aromatic hydrocarbons (PAHs). However, most of the PAH studies using polar cod rely on targeted biomarker-based analysis thus may not adequately address the complexity of the toxic mechanisms of the stressors. The present study was performed to develop a broad-content transcriptomic platform for polar cod and apply it for understanding the toxic mechanisms of a model PAH, benzo(a)pyrene (BaP). Hepatic transcriptional analysis using a combination of high-density polar cod oligonucleotide microarray and quantitative real-time RT-PCR was conducted to characterize the stress responses in polar cod after 14d repeated dietary exposure to 0.4 (Low) and 20.3?µg/g fish/feeding (High) BaP doses. Bile metabolic analysis was performed to identify the storage of a key BaP hepatic biotransformation product, 3-hydroxybenzo(a)pyrene (3-OH-BaP). The results clearly showed that 3-OH-BaP was detected in the bile of polar cod after both Low and High BaP exposure. Dose-dependent hepatic stress responses were identified, with Low BaP suppressing genes involved in the defense mechanisms and High BaP inducing genes associated with these pathways. The results suggested that activation of the aryl hydrocarbon receptor signaling, induction of oxidative stress, DNA damage and apoptosis were the common modes of action (MoA) of BaP between polar cod or other vertebrates, whereas induction of protein degradation and disturbance of mitochondrial functions were proposed as novel MoAs. Furthermore, conceptual toxicity pathways were proposed for BaP-mediated effects in Arctic fish. The present study has for the first time reported a transcriptome-wide analysis using a polar cod-specific microarray and suggested novel MoAs of BaP. The analytical tools, bioinformatics solutions and mechanistic knowledge generated by this study may facilitate mechanistically-based hazard assessment of environmental stressors in the Arctic using this important fish as a model species.
PubMed ID
30408666 View in PubMed
Less detail

9 records – page 1 of 1.