| 1. |
- Aksmann, Anna, et al.
(author)
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The mechanism of anthracene interaction with photosynthetic apparatus : A study using intact cells, thylakoid membranes and PS II complexes isolated from Chlamydomonas reinhardtii
- 2011
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In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 104:3-4, s. 205-210
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Journal article (peer-reviewed)abstract
- Intact cells of Chlamydomonas reinhardtii as well as isolated thylakoid membranes and photosystem II complexes were used to examine a possible mechanism of anthracene (ANT) interaction with the photosynthetic apparatus. Since ANT concentrations above 1 mM were required to significantly inhibit the rate of oxygen evolution in PS II membrane fragments it may indicate that the toxicant did not directly interact with this photosystem. On the other hand, stimulation of oxygen uptake by ANT-treated thylakoids suggested that ANT could either act as an artificial electron acceptor in the photosynthetic electron transport chain or function as an uncoupler. Electron transfer from excited chlorophyll to ANT is impossible due to the very low reduction potential of ANT and therefore we propose that toxic concentrations of ANT increase the thylakoid membrane permeability and thereby function as an uncoupler, enhancing electron transport in vitro. Hence, its unspecific interference with photosynthetic membranes in vitro suggests that the inhibitory effect observed on intact cell photosynthesis is caused by uncoupling of phosphorylation.
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| 2. |
- Albertsson, Eva, 1979, et al.
(author)
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Induction of hepatic carbonyl reductase/20beta-hydroxysteroid dehydrogenase mRNA in rainbow trout downstream from sewage treatment works--possible roles of aryl hydrocarbon receptor agonists and oxidative stress.
- 2010
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In: Aquatic toxicology (Amsterdam, Netherlands). - : Elsevier BV. - 1879-1514 .- 0166-445X. ; 97:3, s. 243-9
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Journal article (peer-reviewed)abstract
- Carbonyl reductase/20beta-hydroxysteroid dehydrogenase (CR/20beta-HSD) serves both as a key enzyme in the gonadal synthesis of maturing-inducing hormone in salmonids, and as an enzyme protecting against certain reactive oxygen species. We have previously shown that mRNA of the hepatic CR/20beta-HSD B isoform is increased in rainbow trout caged downstream from a Swedish sewage treatment plant. Here, we report an increase of both the A as well as B form in fish kept downstream from a second sewage treatment plant. The two mRNAs were also induced in fish hepatoma cells in vitro after exposure to effluent extract. This indicates that the effects observed in vivo could be a direct effect on the liver, i.e. the mRNA induction does not require a signal from any other organ. When fish were exposed in vivo to several effluents treated with more advanced methods (ozone, moving bed biofilm reactor or membrane bioreactor) the expression of hepatic mRNA CR/20beta-HSD A and B was significantly reduced. Their abundance did not parallel the reduction of estrogen-responsive transcripts, in agreement with our previous observations that ethinylestradiol is not a potent inducer. Treatment with norethisterone, methyltestosterone or hydrocortisone in vivo did not induce the hepatic CR/20beta-HSD A and B mRNA expression. In contrast, both isoforms were markedly induced by the aryl hydrocarbon receptor agonist beta-naphthoflavone as well as by the pro-oxidant herbicide paraquat. We hypothesize that the induction of CR/20beta-HSD A and B by sewage effluents could be due to anthropogenic contaminants stimulating the aryl hydrocarbon receptor and/or causing oxidative stress.
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| 3. |
- Asker, Noomi, 1968, et al.
(author)
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Hepatic transcriptome profiling indicates differential mRNA expression of apoptosis and immune related genes in eelpout (Zoarces viviparus) caught at Göteborg harbor, Sweden
- 2013
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In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 130-131, s. 58-67
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Journal article (peer-reviewed)abstract
- The physiology and reproductive performance of eelpout (Zoarces viviparus) have been monitored along the Swedish coast for more than three decades. In this study, transcriptomic profiling was applied for the first time as an exploratory tool to search for new potential candidate biomarkers and to investigate possible stress responses in fish collected from a chronically polluted area. An oligonucleotide microarray with more than 15,000 sequences was used to assess differentially expressed hepatic mRNA levels in female eelpout collected from the contaminated area at Göteborg harbor compared to fish from a national reference site, Fjällbacka. Genes involved in apoptosis and DNA damage (e.g., SMAC/diablo homolog and DDIT4/DNA-damage-inducible protein transcript 4) had higher mRNA expression levels in eelpout from the harbor compared to the reference site, whereas mRNA expression of genes involved in the innate immune system (e.g., complement components and hepcidin) and protein transport/folding (e.g., signal recognition particle and protein disulfide-isomerase) were expressed at lower levels. Gene Ontology enrichment analysis revealed that genes involved biological processes associated with protein folding, immune responses and complement activation were differentially expressed in the harbor eelpout compared to the reference site. The differential mRNA expression of selected genes involved in apoptosis/DNA damage and in the innate immune system was verified by quantitative PCR, using the same fish in addition to eelpout captured four years later. Thus, our approach has identified new potential biomarkers of pollutant exposure and has generated hypotheses on disturbed physiological processes in eelpout. Despite a higher mRNA expression of genes related to apoptosis (e.g., diablo homolog) in eelpout captured in the harbor there were no significant differences in the number of TUNEL-positive apoptotic cells between sites. The mRNA level of genes involved in apoptosis/DNA damage and the status of the innate immune system in fish species captured in polluted environments should be studied in more detail to lay the groundwork for future biomonitoring studies.
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| 4. |
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| 5. |
- Behrendt, Lars, et al.
(author)
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Induction of cytochrome P450 1 genes and stress response genes in developing zebrafish exposed to ultraviolet radiation
- 2010
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In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 98:1, s. 74-82
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Journal article (peer-reviewed)abstract
- Ultraviolet (UV) radiation damages cell molecules, and has been suggested to up-regulate mammalian cytochrome P4501 (CYP1) genes through an aryl hydrocarbon receptor (AHR) mediated mechanism. In this study, embryos and larvae of zebrafish (Danio rerio) were exposed to UV to determine the effects on expression of CYP1 and stress response genes in vivo in these fish. Zebrafish embryos were exposed for varying times to UV on two consecutive days, with exposure beginning at 24 and 48h post-fertilization (hpf). Embryos exposed for 2, 4 or 6h twice over 2 days to UVB (0.62 W/m(2); 8.9-26.7 kJ/m(2)) plus UVA (2.05 W/m(2); 29.5-144.6 kJ/m(2)) had moderately (2.4+/-0.8-fold) but significantly up-regulated levels of CYP1A. UVA alone had no effect on CYP1A expression. Proliferating cellular nuclear antigen (PCNA) and Cu-Zn superoxide dismutase (SOD1) transcript levels were induced (2.1+/-0.2 and 2.3+/-0.5-fold, respectively) in embryos exposed to two 6-h pulses of 0.62 W/m(2) UVB (26.8 kJ/m(2)). CYP1A was induced also in embryos exposed to higher intensity UVB (0.93 W/m(2)) for two 3-h or two 4-h pulses (20.1 or 26.8 kJ/m(2)). CYP1B1, SOD1 and PCNA expression was induced by the two 3-h pulses of the higher intensity UVB, but not after two 4-h pulses of the higher intensity UVB, possibly due to impaired condition of surviving embryos, reflected in a mortality of 34% at that UVB dose. A single 8-h long exposure of zebrafish larvae (8dpf) to UVB at 0.93 W/m(2) (26.8 kJ/m(2)) significantly induced CYP1A and CYP1B1 expression, but other CYP1 genes (CYP1C1, CYP1C2 and CYP1D1) showed no significant increase. The results show that UVB can induce expression of CYP1 genes as well stress response genes in developing zebrafish, and that UVB intensity and duration influence the responses.
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| 6. |
- Beijer, Kristina, et al.
(author)
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CYP1A inhibition in fish gill filaments : a novel assay applied on pharmaceuticals and other chemicals
- 2010
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In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 96:2, s. 145-150
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Journal article (peer-reviewed)abstract
- The gill filament 7-ethoxyresorufin O-deethylase (EROD) assay was originally developed as a biomarker for cytochrome P4501A (CYP1A) induction by Ah-receptor agonists in water. In this study, the assay was adapted to measure inhibition of CYP1A activity in fish gill filaments ex vivo. The experiments were carried out using gill arch filaments from beta-naphthoflavone (betaNF)-exposed three-spined stickleback (Gasterosteus aculeatus). Candidate CYP1A inhibitors were added to the assay buffer. Nine selected pharmaceuticals and five known or suspected CYP1A-modulating chemicals were examined with regard to their ability to reduce EROD activity in gill filaments. Ellipticine, a well characterized CYP1A inhibitor, was the most effective inhibitor of the compounds tested. At a concentration in the assay buffer of 1 microM the antifungal azoles ketoconazole, miconazole and bitertanol, and the plant flavonoid acacetin reduced gill EROD activity by more than 50%, implying IC50 values below 1 microM. These compounds have previously been shown to inhibit EROD activity in liver microsomes from fish and mammals at similar concentrations. The proton pump inhibitor omeprazole reduced the gill EROD activity by 39% at 10 microM. It is concluded that the modified gill filament EROD assay is useful to screen for waterborne pollutants that inhibit catalytic CYP1A activity in fish gills.
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| 7. |
- Bundschuh, Mirco
(author)
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Effects of current-use fungicides and their mixtures on the feeding and survival of the key shredder Gammarus fossarum
- 2014
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In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 150, s. 133-143
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Journal article (peer-reviewed)abstract
- Fungicides are frequently applied in agriculture and are subsequently detected in surface waters in total concentrations of up to several tens of micrograms per liter. These concentrations imply potential effects on aquatic communities and fundamental ecosystem functions such as leaf litter breakdown. In this context, the present study investigates sublethal and lethal effects of organic (azoxystrobin, carbendazim, cyprodinil, quinoxyfen, and tebuconazole) and inorganic (three copper (Cu)-based substances and sulfur) current-use fungicides and their mixtures on the key leaf-shredding invertebrate Gammarus fossarum. The feeding activity of fungicide-exposed gammarids was quantified as sublethal endpoint using a static (organic fungicides; 7 d test duration) or a semi-static (inorganic fungicides; 6 d test duration with a water exchange after 3 d) approach (n = 30). EC50-values of organic fungicides were generally observed at concentrations resulting in less than 20% mortality, with the exception of carbendazim. With regard to feeding, quinoxyfen was the most toxic organic fungicide, followed by cyprodinil, carbendazim, azoxystrobin, and tebuconazole. Although all tested organic fungicides have dissimilar (intended) modes of action, a mixture experiment revealed a synergistic effect on gammarids' feeding at high concentrations when using "independent action" as the reference model (similar to 35% deviation between predicted and observed effect). This may be explained by the presence of a synergizing azole fungicide (i.e. tebuconazole) in this mixture. Furthermore, lethal concentrations of all Cu-based fungicides assessed in this study were comparable amongst one another. However, they differed markedly in their effective concentrations when using feeding activity as the endpoint, with Cu-sulfate being most toxic, followed by Cu-hydroxide and Cu-octanoate. In contrast, sulfur neither affected survival nor the feeding activity of gammarids (up to similar to 5 mg/L) but reduced Cu-sulfate's toxicity when applied in a binary mixture. Sulfur-related metabolic processes which reduce the physiological availability of Cu may explain this antagonistic effect. For both fungicide mixtures, the present study thus uncovered deviations from the appropriate reference model, while ecotoxicological effects were observed at field relevant (total) fungicide concentrations. Additionally, for more than half of the tested single substances, a potential risk for Gammarus and thus for the ecological function mediated by these organisms was evident at concentrations measured in agriculturally influenced surface waters. These results suggest that risks to the fundamental ecosystem function of leaf litter breakdown posed by fungicides may not be adequately considered during the regulation of these compounds, which makes further experimental efforts necessary. (C) 2014 Elsevier B.V. All rights reserved.
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| 8. |
- Bundschuh, Mirco
(author)
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Nanoparticle toxicity in Daphnia magna reproduction studies: The importance of test design
- 2013
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In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 126, s. 163-168
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Journal article (peer-reviewed)abstract
- The increasing use of titanium dioxide nanoparticles (nTiO(2)) inevitably results in their release into the environment, raising concerns about potential adverse effects in wildlife. By following standard test protocols, several studies investigated the ecotoxicity of nTiO(2) among others to Daphnia magna. These studies indicated a large variability - several orders of magnitude - in the response variables. However, other factors, like nanoparticle characteristics and test design, potentially triggering these differences, were largely ignored. Therefore, the present study assessed the chronic ecotoxicity of two nTiO(2) products with varying crystalline structure (A-100; P25) to D. magna. A semi-static and a flow-through exposure scenario were compared, ensuring that both contained environmentally relevant concentrations of dissolved organic carbon. Utilizing the semi-static test design, a concentration as low as 0.06 mg/L A-100 (similar to 330 nm) significantly reduced the reproduction of daphnia indicating environmental risk. In contrast, no implication in the number of released offspring was observed during the flow-through experiment with A-100 (similar to 140 nm). Likewise, P25 (similar to 130 nm) did not adversely affect reproduction irrespective of the test design utilized. Given the present study's results, the particle size, the product composition, i.e. the crystalline structure, and the accumulation of nTiO(2) at the bottom of the test vessel - the latter is relevant for a semi-static test design - may be suggested as factors potentially triggering differences in nTiO(2) toxicity to D. magna. Hence, these factors should be considered to improve environmental risk assessment of nanoparticles. (c) 2012 Elsevier B.V. All rights reserved.
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| 9. |
- Carlsson, Gunnar, et al.
(author)
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Toxicity of 15 veterinary Pharmaceuticals in zebrafish (Danio rerio) embryos
- 2013
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In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 126, s. 30-41
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Journal article (peer-reviewed)abstract
- Extensive use of veterinary pharmaceuticals may result in contamination of water bodies adjacent to pasture land or areas where animal manure has been applied. In order to evaluate the potential risk to fish embryos 15 veterinary pharmaceuticals were investigated by use of an extended zebrafish embryo toxicity test. Chemical analysis of the exposure medium was performed by solid phase extraction-liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS) for 11 of the compounds and potential metabolism by the embryos was studied for albendazole, febantel, fenbendazole and oxfendazole. Newly fertilized zebrafish eggs were exposed under static conditions in 96-well plates for 6 days to the pharmaceuticals: 5 antibacterials and 10 antiparasitics. Endpoints including mortality, malformations and other sublethal responses were recorded at 24, 48 and 144 h post fertilization (hpf). The pharmaceuticals causing the highest toxicity were antiparasitics whereas the tested antibacterials, danofloxacin, enrofloxacin, tylosine, trimethoprim and oxytetracyclin had a much lower toxic potency in zebrafish embryos. Most toxic were fenbendazole, albendazole and flumethrin with no observed effect concentrations (NOECs) around 0.02 mg/L. The overall NOEC was determined by lethality for the following pharmaceuticals: albendazole, fenbendazole and oxfendazole. Sublethal endpoints, including malformations, side-laying embryos, tremors, reduced movements and altered heart rate increased the sensitivity of the tests and determined the overall NOECs for febantel, doramectin, ivermectin, flumethrin and toltrazuril. Exposure to doramectin and ivermectin caused a decrease in movements at 24 hpf and a decrease in heart rate at 48 hpf. Flumethrin exposure resulted in decreased time to hatching, except at the highest concentrations, and caused an increase in heart rate at 48 hpf. In contrast, toltrazuril caused an increased time to hatching and a decrease in heart rate. Chemical analysis of the exposure medium after the tests revealed great differences between nominal and measured concentrations, emphasizing the need of including analysis of the actual exposure concentrations. The results indicated that metabolism of albendazole into its sulfoxide protected the embryos from toxicity. Albendazole was metabolized efficiently into albendazole sulfoxide at lower exposure concentrations, resulting in reduced toxicity. At higher concentrations, an increasing proportion of albendazole remained unmetabolized and embryo mortality occurred. Metabolism by the embryos of febantel into fenbendazole and oxfendazole and of fenbendazole into oxfendazole was demonstrated. It is suggested that the toxic effect of febantel in zebrafish embryos is due to metabolism into fenbendazole.
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| 10. |
- Ericson, Hanna, et al.
(author)
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Physiological effects of diclofenac, ibuprofen and propranolol on Baltic Sea blue mussels
- 2010
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In: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 99:2, s. 223-231
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Journal article (peer-reviewed)abstract
- Pharmaceuticals are constantly dispersed into the environment and little is known of the effects on non-target organisms. This is an issue of growing concern. In this study, Baltic Sea blue mussels, Mytilus edulis trossulus, were exposed to diclofenac, ibuprofen and propranolol, three pharmaceuticals that are produced and sold in large quantities and have a widespread occurrence in aquatic environments. The mussels were exposed to pharmaceuticals in concentrations ranging from 1 to 10,000 mu g l(-1). The pharmaceuticals were added both separately and in combination. Mussels exposed to high concentrations of pharmaceuticals showed a clear response compared to controls. Firstly, they had a significantly lower scope for growth, which indicates that the organisms had a smaller part of their energy available for normal metabolism, and secondly, they had lower byssus strength and lower abundance of byssus threads, resulting in reduced ability to attach to the underlying substrate. Mussels exposed to lower concentrations showed tendencies of the same results. The concentration of diclofenac and propranolol was quantified in the mussels using both liquid chromatography coupled to mass spectrometry (LC-MS). The measurements showed a significantly higher concentration in the organisms as compared to the water the mussels were exposed to; the uptake reached concentrations two orders of magnitudes higher than found in sewage treatment plant effluents. This study showed that common pharmaceuticals are taken up and negatively affect the physiology of a non-target species at levels of two to three orders of magnitudes higher than found in sewage treatment plant effluents.
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