Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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    Initial sample extract stock concentration affects in vitro bioassay-based toxicological risk characterization
    Montano, M. ; Loffmann, L. ; Murk, A.J. ; Gutleb, A.C. - \ 2014
    Journal of Soils and Sediments 14 (2014)6. - ISSN 1439-0108 - p. 1200 - 1212.
    effect-directed analysis - suspended particulate matter - persistent organic pollutants - gene-expression calux - dioxin-like compounds - aromatic-hydrocarbons - river sediments - flood events - endocrine disruption - estrogenic activity
    Purpose Bioassays have become an alternative for sediment risk profiling, including potential compliance with sediment quality criteria (SQC). In vitro functional bioassays have evolved through standardization and validation towards a confident toxicological hazard estimate of sediments. Sample preparation is a key aspect for the improvement of bioassays. It is a standard practice to use a high single-stock concentration of extracts to further dilute test concentrations from and carry out the analysis. This study was carried out to demonstrate that high a contaminant load in a sediment extract (>20 g sediment equivalents (SEQ) ml-1) oversaturates solubility in carrier solvents and overloads the clean-up columns, potentially resulting in an under- or overestimation of the quantified dioxin-like toxic potency. Materials and methods Cleaned nonpolar sediment extracts were prepared from samples collected from various locations in Luxembourg. The influence on the quantified toxic potency of the initial stock concentration, sonication assisted dissolution and exposure period in an in vitro bioassay for dioxin-like toxic potency (Bio-TEQ) was evaluated, as well as its impact on the sediment risk characterization according to SQC. Results and discussion Stock sonication before serial dilution strongly reduced the standard variation of the outcomes. Higher initial stock concentrations (>20 g SEQ ml-1 for contaminated sediments) produced significantly lower Bio-TEQs g SEQ-1 compared to those obtained with initial stock concentrations of 2 g SEQ ml-1, probably due to solvent oversaturation. An initial stock concentration of 2 g SEQ ml-1 is low enough to prevent mis-estimation, but 20 or even 200 g SEQ ml-1 might be used when quantification of Bio-TEQ is required. The overload of extract on clean-up columns caused an overestimation of the dioxin-like potency probably due to PAH-induced false-positive responses. Conclusions Higher contaminant load in the initial extracts from sediments affects the reliability of in vitro Bio-TEQ sediment quantification. Advice is given on how to avoid underestimation because of extract oversaturation, avoid overestimation because of overload of clean-up columns and reduce variability by applying sonication in standard testing protocols for risk characterization and quantification of the sample’s toxic potency. Taking into account the new aspects revealed in this study, in addition to important issues for quality control that are already included, the in vitro bioassays based on Bio-TEQs can be applied in a comprehensive monitoring program to determine whether sediments comply with health and safety standards for humans and the environment.
    Metabolic Activation of Nonpolar Sediment Extracts Results in enhanced Thyroid Hormone Disrupting Potency
    Montano, M. ; Weiss, J. ; Hoffmann, L. ; Gutleb, A.C. ; Murk, A.J. - \ 2013
    Environmental Science and Technology 47 (2013)15. - ISSN 0013-936X - p. 8878 - 8886.
    persistent organic pollutants - brominated flame retardants - effect-directed analysis - halogenated aromatic-hydrocarbons - polybrominated diphenyl ethers - in-vitro - polychlorinated-biphenyls - endocrine disruption - estrogenic activity - hepatic microsomes
    Traditional sediment risk assessment predominantly considers the hazard derived from legacy contaminants that are present in nonpolar sediment extracts, such as polychlorinated biphenyls (PCBs), dioxins, furans (PCDD/Fs), and polyaromatic hydrocarbons (PAHs). Although in vivo experiments with these compounds have shown to be thyroid hormone disrupting (THD), in vitro their THD potency is not observed in nonpolar sediment extracts. This is hypothesized to be due to the absence of in vitro biotransformation which will result in bioactivation of the lipophilic compounds into THD hydroxyl metabolites. This study reveals that indeed metabolically activated nonpolar contaminants in sediments can competitively bind to thyroid hormone transport proteins. Sediment fractions were incubated with S9 rat microsomes, and the metabolites were extracted with a newly developed method that excludes most of the lipids to avoid interference in the applied nonradioactive 96-well plate TTR competitive binding assay. Metabolic activation increased the TTR binding potency of nonpolar fractions of POP-polluted sediments up to 100 times, resulting in potencies up to 240 nmol T4 equivalents/g sediment equivalent (nmol T4-Eq/g SEQ). This demonstrates that a more realistic in vitro sediment THD risk characterization should also include testing of both polar and medium polar sediment extracts for THD, as well as bioactivated nonpolar sediment fractions to prevent underestimation of its toxic potency.
    Applicability of a yeast bioassay in the detection of steroid esters in hair
    Becue, I. ; Bovee, T.F.H. ; Poucke, C. ; Groot, M.J. ; Nielen, M.W.F. ; Peteghem, C. van - \ 2011
    Analytical and Bioanalytical Chemistry 399 (2011)3. - ISSN 1618-2642 - p. 1031 - 1039.
    green fluorescent protein - tandem mass-spectrometry - estrogenic activity - bovine hair - estradiol benzoate - anabolic-steroids - calf urine - validation - samples - expression
    The aim of the present study was to demonstrate the applicability of a yeast androgen and estrogen bioassay in the detection of steroid esters in hair samples of animals treated with a hormone ester cocktail. The outcome of the activity screenings was critically compared with the results previously obtained with LC-MS/MS analysis. Hair samples of one pour-on treated animal, 10 ml DMSO containing 25 mg estradiol benzoate (EB), 60 mg testosterone decanoate (TD) and 60 mg testosterone cypionate (TC), were selected and analyzed with the androgen and estrogen yeast bioassay. Results showed that by the introduction of a hydrolysis step, bioassays can be used to screen for the presence of hormone esters in hair samples. Based on the difference in fluorescence responses between the nonhydrolyzed and the hydrolyzed hair samples, it was possible to detect the presence of EB up to at least 56 days after a single pour-on treatment and to detect the presence of TC and TD up to at least 14 days after the treatment. Although the LC-MS/MS analysis could detect TC and TD up to 49 days after treatment, bioassays have the advantage that they can also detect any (un)known steroid ester. Keywords Testosterone ester . Estradiol benzoate . Yeast bioassay . Untargeted analysis . Hair
    Application of bioassays in toxicological hazard, risk and impact assessments of dredged sediments
    Schipper, C.A. ; Rietjens, I.M.C.M. ; Burgerss, R.M. ; Murk, A.J. - \ 2010
    Marine Pollution Bulletin 60 (2010)11. - ISSN 0025-326X - p. 2026 - 2042.
    in-vitro bioassay - polyhalogenated aromatic-hydrocarbons - marine harbor sediments - dioxin-like compounds - reporter gene assays - north-sea - estrogenic activity - expression calux - dutch marine - lutra-lutra
    Given the potential environmental consequences of dumped dredged harbour sediments it is vital to establish the potential risks from exposure before disposal at sea. Currently, European legislation for disposal of contaminated sediments at sea is based on chemical analysis of a limited number of well-known contaminants for which maximum acceptable concentrations, action levels (ALs), have been set. The present paper addresses the issue of the applicability of in vitro and in vivo bioassays for hazard, risk and local impact assessment of dredged polluted sediments to be disposed of at sea. It discusses how and to what extent selected bioassays can fill in the gaps left open by chemical analysis and the way in which the bioassays may contribute to the present licensing system for disposal. Three different purposes for application were distinguished: the most basic application (A) is a rapid determination of the hazard (potential toxicity) of dredged sediments which is then compared to ALs in a licensing system. As with chemical analysis on whole sediment extracts, the bioavailability of the chemicals is not taken into account. As in vitro assays with sediment extracts are not sensitive to matrix effects, a selection of specific in vitro bioassays can be suitable fast and standardized additions for the licensing system. When the outcome of (A) does not convincingly demonstrate whether the sediment is clean enough or too polluted, further bioanalysis can help the decision making process (B). More aspects of the mostly unknown complex chemical mixtures are taken into account, including the bioavailability and chronic toxicity focusing on ecologically relevant endpoints. The ecotoxicological pressure imposed by the dredged sediments can be quantified as the potentially affected fraction (PAF) based on chemical or biological analysis of levels of contaminants in sediment or biota. To validate the predicted risk, the actual impact of dumped harbour sediments on local ecosystems (C) can be determined using a dedicated set of in vitro and in vivo bioassays as well as bio-indicators selected based on the information obtained from (A) and (B) and on the characteristics of the local ecosystem. Conversely, the local sediment impact assessment (C) can direct fine-tuning of the selection of chemical and bioassay analyses and for setting safe levels in the licensing system. It is concluded that in vitro and in vivo bioassays and biological indicators are useful tools in the process of hazard, ecotoxicological risk and impact assessment of dredged harbour sediments, provided they are consciously chosen and quality criteria for assay performance are defined.
    Occurrence of xenobiotics in gray water and removal in three biological treatment systems
    Hernandez Leal, L. ; Vieno, N. ; Temmink, B.G. ; Zeeman, G. ; Buisman, C.J.N. - \ 2010
    Environmental Science and Technology 44 (2010)17. - ISSN 0013-936X - p. 6835 - 6842.
    personal-care products - tandem mass-spectrometry - solid-phase extraction - waste-water - uv filters - aquatic environment - polycyclic musks - in-vitro - estrogenic activity - treatment plants
    Eighteen selected xenobiotics related to personal care and household chemicals (UV-filters, fragrances, preservatives, biocides, surfactants) were measured in gray water from 32 houses and in effluents of three different biological treatment systems (aerobic, anaerobic, and combined anaerobic + aerobic). All selected xenobiotics were detected in gray water samples in the low µg L-1 range. Generally, lower concentrations were measured after biological treatment and removal efficiencies were higher under aerobic conditions than under anaerobic conditions. However, most of the xenobiotics were still detected in biologically treated gray water. The most persistent compounds were the fragrance tonalide and the UV-filters 2-phenyl-5-benzimidazolesulfonic acid and ethylhexyl methoxycinnamate. Estimated estrogenic potential of the effluent ranged between 0.07 and 0.72 ng L-1 of 17ß-estradiol equivalents. Depending on the application of the effluent and its environmental risk, physical-chemical processes might be required to increase the removal efficiency of these compounds from gray water
    A retrospective analysis to explore the applicability of fish biomarkers and sediment bioassays along contaminated salinity transects
    Schipper, C.A. ; Lahr, J. ; Brink, P.J. van den; George, S.G. ; Hansen, P.D. ; Silva de Assis, H.C. Da; Oost, R. van der; Thain, J.E. ; Livingstone, D. ; Mitchelmore, C. ; Schooten, F.J. van; Ariese, F. ; Murk, A.J. ; Grinwis, G.C.M. ; Klamer, H. ; Kater, J. ; Postma, J.F. ; Werf, B. van der; Vethaak, A.D. - \ 2009
    ICES Journal of Marine Science 66 (2009)10. - ISSN 1054-3139 - p. 2089 - 2105.
    flounder platichthys-flesus - plaice pleuronectes-platessa - oxygen species production - united-kingdom estuarine - reporter gene assays - river tyne estuary - in-vitro bioassay - estrogenic activity - north-sea - organic contaminants
    Biological-effects monitoring in estuarine environments is complex as a result of strong gradients and fluctuations in salinity and other environmental conditions, which may influence contaminant bioavailability and the physiology and metabolism of the organisms. To select the most robust and reliable biological-effect methods for monitoring and assessment programmes, a large-scale field study was conducted in two estuarine transects in the Netherlands. The locations ranged from heavily polluted harbour areas (the ports of Rotterdam and Amsterdam) to cleaner coastal and freshwater sites. Assessment methods used included a variety of biomarkers in flounder (Platichthys flesus) and a range of in vitro (sediment extracts) and in vivo bioassays. Multivariate statistical analysis was applied to investigate correlations and relationships between various biological effects and contaminant levels in flounder liver or sediments. Several biological methods seemed to be too much affected by salinity differences for routine use in estuaries. The most discriminative biomarkers in the study were hepatic metallothionein content and biliary 1-OH pyrene in fish. Mechanism-based in vitro assays DR-CALUX and ER-CALUX applied to sediment extracts for screening of potential toxicity were much more responsive than in vivo bioassays with macro-invertebrates using survival as an endpoint
    Specific in vitro toxicity of crude and refined petroleum products. 1. Aryl hydrocarbon receptor-mediated responses
    Vrabie, C.M. ; Jonker, M.T.O. ; Murk, A.J. - \ 2009
    Environmental Toxicology and Chemistry 28 (2009)9. - ISSN 0730-7268 - p. 1995 - 2003.
    polycyclic aromatic-hydrocarbons - ah receptor - estrogenic activity - aquatic toxicity - complex-mixtures - heavy oil - assay - gene - agonists - fuel
    The present study is the first in a series reporting on in vitro toxic potencies of oils. The objective was to determine whether 11 crude oils and refined products activate the aryl hydrocarbon receptor (AhR) in a dioxin receptor¿mediated luciferase assay. Cells were exposed for 6 and 24 h to different oil concentrations to screen for polycyclic aromatic hydrocarbon¿like or dioxin-like activity. Moreover, cytotoxicity of the oils was determined using rat hepatoma cells. Except for one crude oil, none of the oils appeared cytotoxic up to 100 mg/L, but all oils activated the AhR. Strong AhR induction was observed for most oils after 6 h, and responses decreased after 24 h, indicating the presence of metabolizable agonists. However, several oils still caused high responses after 24 h, also demonstrating the presence of persistent agonists. The potencies (calculated based on comparisons of concentrations at which 50% of the maximal effect was observed) of oils were found to be approximately 40 to 106 times lower than the potency of the assay's standards benzo[a]pyrene and 2,3,7,8-tetrachlorodibenzo-p-dioxin. However, considering that oils contain thousands of chemicals, the potencies of petrochemical agonists may be very high. Among the most potent oils were bunker and crude oils. Induction up to 200% as compared to the maximum induction caused by benzo[a]pyrene was observed for these oils. Such supermaximal responses suggest mixture effects that may not be receptor-mediated. Experiments in which oils were tested in combination with the standards demonstrated that oils acted via an antagonistic or additive mode. The results of the present study may help improve risk assessment of petroleum products and judge the necessity or priority of oil spill cleanup activities
    Validation and application of a yeast bioassay for screening androgenic activity in calf urine and feed
    Bovee, T.F.H. ; Bor, G. ; Heskamp, H.H. ; Lasaroms, J.J.P. ; Sanders, M.B. ; Nielen, M.W.F. - \ 2009
    Analytica Chimica Acta 637 (2009)1-2. - ISSN 0003-2670 - p. 225 - 234.
    tandem mass-spectrometry - in-vitro - liquid-chromatography - estrogenic activity - recombinant assay - anabolic-steroids - receptor ligands - surface waters - binding - dihydrotestosterone
    Bioassays are valuable tools for combating the illegal use of steroids in cattle fattening. Previously we described the construction and properties of a rapid and robust yeast androgen bioassay stably expressing the human androgen receptor (hAR) and yeast enhanced green fluorescent protein (yEGFP), the latter in response to androgens. In the present study this yeast androgen bioassay was validated as a qualitative screening method for the determination of androgenic activity in calf urine and animal feed. This validation was performed according to EC Decision 2002/657. 20 blank samples were spiked with testosterone, 17¿-methyltestosterone, 19-nortestosterone, 17ß-trenbolone, 17ß-boldenone or 17¿-methylboldenone at 2 or 15 ng mL¿1 in urine and 50 or 100 ng g¿1 in feed. All blank and spiked samples fulfilled the CC¿ and CCß criterions, meaning that all 20 blank samples gave signals below the determined decision limits CC¿ and were thus classified as compliant (¿ = 1%). For each component, at least 19 out of the 20 spiked samples gave a signal above the CC¿ and were thus classified as suspect (ß = 5%). The method was specific, and high amounts of dexamethasone did not interfere with the outcome of the test. Although high levels of 17¿-ethynylestradiol can significantly inhibit the response obtained with low amounts of androgens, that situation is not relevant in veterinary practice. When stored at their specific conditions, the androgens in feed were stable for at least 91 days. Real urine samples from a national control program were screened and a representative part of the compliant and suspect samples were confirmed by gas chromatography¿tandem mass spectrometry
    Bioavailability and biodegradation of nonylphenol in sediment determined with chemical and bioanalysis
    Weert, J.P.A. de; Cal, A. de la; Berg, J.H.J. van den; Murk, A.J. ; Langenhoff, A.A.M. ; Rijnaarts, H.H.M. ; Grotenhuis, J.T.C. - \ 2008
    Environmental Toxicology and Chemistry 27 (2008)4. - ISSN 0730-7268 - p. 778 - 785.
    organic-compounds - nonionic surfactants - estrogenic activity - rainbow-trout - in-vitro - soils - 4-nonylphenol - contaminants - pollutants - river
    The surfactant nonylphenol (NP) is an endocrine-disrupting compound that is widely spread throughout the environment. Although environmental risk assessments are based on total NP concentrations, only the bioavailable fraction posses an environmental risk. The present study describes the bioavailability and biodegradability of NP over time in contaminated river sediment of a tributary of the Ebro River in Spain. The bioavailable fraction was collected with Tenax TA® beads, and biodegradation was determined in aerobic batch experiments. The presence of NP was analyzed chemically using gas chromatography¿mass spectrometry and indirectly as estrogenic potency using an in vitro reporter gene assay (ER¿-luc assay). Of the total extractable NP in the sediment, 95% ± 1.5% (mean ± standard error) desorbed quickly into the water phase. By aerobic biodegradation, the total extractable NP concentration and the estrogenic activity were reduced by 97% ±0.5% and 94% ± 2%, respectively. The easily biodegradable fraction equals the potential bioavailable fraction. Only 43 to 86% of the estrogenic activity in the total extractable fraction, as detected in the ER¿-luc assay, could be explained by the present NP concentration. This indicates that other estrogenic compounds were present and that their bioavailability and aerobic degradation were similar to that of NP. Therefore, we propose to use NP as an indicator compound to monitor estrogenicity of this Ebro River sediment. To what extent this conclusion holds for other river sediments depends on the composition of the contaminants and/or the nature of these sediments and requires further testing
    A new highly androgen specific yeast biosensor, enabling optimisation of (Q)SAR model approaches
    Bovee, T.F.H. ; Lommerse, J.P.M. ; Peijnenburg, A.A.C.M. ; Fernandes, E.A. ; Nielen, M.W.F. - \ 2008
    Journal of Steroid Biochemistry and Molecular Biology 108 (2008)1-2. - ISSN 0960-0760 - p. 121 - 131.
    ligand-binding domains - estrogenic activity - receptor ligands - response element - in-vitro - assay - validation - mutations - bioassays - agonists
    Recently we constructed recombinant yeast cells that express the human androgen receptor (hAR) and yeast enhanced green fluorescent protein (yEGFP), the latter in response to androgens. When exposed to 17ß-testosterone, the concentration where half-maximal activation is reached (EC50) was 50 nM. Relative androgenic potencies (RAP), defined as the ratio between the EC50 of 17ß-testosterone and the EC50 of the compound, were 1.7, 1.2 and 0.008 for 19-nortestosterone, tetrahydrogestrinone and 17ß-estradiol respectively. Steroids representative for other hormone receptors, like estrone, 17¿-ethynylestradiol, and diethylstilbestrol for the estrogen receptor and corticosterone and dexamethasone for the glucocorticoid receptor, showed no agonistic response. Only compounds known to exert androgenic effects give a response. Determined RAPs were in line with results obtained from optimised QSAR model calculations and demonstrated that Saccharomyces cerevisiae showed no metabolism of test compounds and displayed no crosstalk from endogenous hormone receptors. The suitability of this bioassay to verify the outcomes of (Q)SAR models to predict the activities of different steroids was further examined by studies with steroid isomers and a number of designer steroids, confirming that the 17ß-hydroxyl group, 3-keto group and 5¿-steroidal framework are extremely important for the activity of the androgenic steroid.
    An in vitro/in vovo screening assay as a sensitive tool to assess endocrine disruptive activity in surface water
    Bogers, R. ; Buitenweg, S. ; Geuijen, I. ; Waart, B. van de; Kuiper, R. ; Linden, S. van der; Puijker, L. ; Murk, A.J. ; Burg, B. van der; Legler, J. - \ 2007
    Environment International 33 (2007)3. - ISSN 0160-4120 - p. 292 - 301.
    minnow pimephales-promelas - vitellogenin messenger-rna - secondary sex characteristics - treated sewage effluent - medaka oryzias-latipes - fathead minnow - cyprinodon-variegatus - estrogenic activity - synthetic estrogen - rainbow-trout
    Adult male fathead minnow were exposed for 14 or 28-days under flow-through conditions to undiluted filtered water samples from the rivers Meuse and Rhine in the Netherlands. The experiment included two vessels per treatment each containing 10 fish and samples of five fish were taken after 14 and 28 days. Additional groups were exposed to 17¿-ethinylestradiol (EE2) as a reference and untreated drinking water as a negative control. Major endpoints examined included induction of vitellogenin (VTG) synthesis, VTG mRNA activity, hepato- and gonadosomatic indices (HSI and GSI) and gonadal histology. No significant difference was recorded in body weight or mean GSI values between the various treatments. Only exposure to Meuse water resulted in significantly higher HSI means after 14 days. Histological examination showed no apparent effects on gonadal tissue except for eosinophilic blood plasma in fish exposed to Meuse water or EE2. After 14 and 28 days, elevated VTG and VTG mRNA levels were measured in most livers of the fish exposed to Meuse water, but not in the fish exposed to Rhine water. This was confirmed by measuring estrogenic responses in the in vitro ER CALUX® assay. Induction of VTG synthesis proved to be the most sensitive endpoint in the Non Spawning Male Fish Assay for in vivo detection of bio-available estrogenic activity supplementary to a sensitive in vitro assay. The other endpoints examined varied too much and required a higher number of fish or replicates to achieve sufficient power for statistical testing making them less animal friendly.
    A new highly specific and robust yeast androgen bioassay for the detection of agonist and antagonists
    Bovee, T.F.H. ; Helsdingen, J.R. ; Hamers, A.R.M. ; Duursen, M. van; Nielen, M.W.F. ; Hoogenboom, L.A.P. - \ 2007
    Analytical and Bioanalytical Chemistry 389 (2007)5. - ISSN 1618-2642 - p. 1549 - 1558.
    green fluorescent protein - in-vitro - estrogenic activity - recombinant assay - response element - receptor-binding - surface waters - transcription - progesterone - validation
    Public concern about the presence of natural and anthropogenic compounds which affect human health by modulating normal endocrine functions is continuously growing. Fast and simple high-throughput screening methods for the detection of hormone activities are thus indispensable. During the last two decades, a panel of different in vitro assays has been developed, mainly for compounds with an estrogenic mode of action. Here we describe the development of an androgen transcription activation assay that is easy to use in routine screening. Recombinant yeast cells were constructed that express the human androgen receptor and yeast enhanced green fluorescent protein (yEGFP), the latter in response to androgens. Compared with other reporters, the yEGFP reporter protein is very convenient because it is directly measurable in intact living cells, i.e., cell wall disruption and the addition of a substrate are not needed. When yeast was exposed to 17 beta-testosterone, the concentration where half-maximal activation is reached (EC50) was 50 nM. The relative androgenic potencies, defined as the ratio between the EC50 of 17 beta-testosterone and the EC50 of the compound, of 5 alpha-dihydrotestosterone, methyltrienolone, and 17 beta-boldenone are 2.3, 1.4, and 0.15 respectively. The results presented in this paper demonstrate that this new yeast androgen bioassay is fast, sensitive, and very specific and also suited to detect compounds that have an antiandrogenic mode of action.
    Androgenic activity in surface water samples detected using the AR-LUX assay: indications for mixture effects
    Blankvoort, B.M.G. ; Rodenburg, R.J.T. ; Murk, A.J. ; Koeman, J.H. ; Schilt, R. ; Aarts, J.M.M.J.G. - \ 2005
    Environmental Toxicology and Pharmacology 19 (2005)2. - ISSN 1382-6689 - p. 263 - 272.
    reporter gene assay - estrogenic activity - cell-line - in-vitro - mass-spectrometry - steroid-hormones - anabolic agents - risk-assessment - cancer cells - testosterone
    This paper describes the screening of 22 extracts from 18 different aquatic environmental samples for androgenic activity, including indirect and interactive effects on androgen receptor (AR)-mediated signal transduction, using the AR-LUX bioassay. Four samples, originating from an industrial wastewater treatment plant (WTP) or the river Meuse, were shown to contain substantial androgenic activity. Moreover, the samples originating from the industrial WTP showed an enhancement of the maximal androgenic response relative to that elicited by the standard androgen methyltrienolone (R1881) in the AR-LUX assay. This indicates the involvement of cellular mechanisms other than receptor-ligand interaction influencing AR-regulated pathways. This also demonstrates the additional value of cell based assays featuring a more complete array of fully functional interacting pathways. Chemical analysis using GC-MS confirmed the presence of a number of androgens and also estrogens in these WTP samples. Subsequently, we showed that estrone and tributyltin hydride (TBT-H) enhance the response to androgens. This indicates that the presence of numerous compounds in addition to androgens in environmental mixtures might very well result in a more profound perturbation of the normal physiology of exposed organisms than estimated based on the androgen levels alone. Therefore, risk assessment of environmental samples should include an evaluation of the presence and the interactive effects of (ant)agonists of carefully selected relevant cellular receptors in order to provide a realistic estimate of the integrated ecotoxicological risk of the compounds present. (C) 2004 Elsevier B.V. All rights reserved.
    Toxicological profiling of sediments with in vitro mechanisms-based bioassays for endocrine disruption
    Houtman, C.J. ; Cenijn, P.H. ; Hamers, T. ; Lamoree, M.H. ; Legler, J. ; Murk, A.J. ; Brouwer, A. - \ 2004
    Environmental Toxicology and Chemistry 23 (2004)1. - ISSN 0730-7268 - p. 32 - 40.
    biotesten - sediment - toxiciteit - hormonen - estuaria - rivieren - nederland - hormoonverstoorders - waterbodems - ecotoxicologie - rijn - maas - bioassays - sediment - toxicity - hormones - estuaries - rivers - netherlands - endocrine disruptors - water bottoms - ecotoxicology - river rhine - river meuse - reporter gene assays - estrogenic activity - aromatic-hydrocarbons - human transthyretin - expression assays - toxic potency - extracts - chemicals - exposure - wildlife
    In vitro bioassays are valuable tools for screening environmental samples for the presence of bioactive (e.g., endocrine-disrupting) compounds. They can be used to direct chemical analysis of active compounds in toxicity identification and evaluation (TIE) approaches. In the present study, five in vitro bioassays were used to profile toxic potencies in sediments, with emphasis on endocrine disruption. Nonpolar total and acid-treated stable extracts of sediments from 15 locations in the Rhine Meuse estuary area in The Netherlands were assessed. Dioxin-like and estrogenic activities (using dioxin-responsive chemical-activated luciferase gene expression [DR-CALUX] and estrogen-responsive chemical-activated luciferase gene expression [ER-CALUX] assays) as well as genotoxicity (UMU test) and nonspecific toxic potency (Vibrio fischeri assay) were observed in sediment extracts. For the first time, to our knowledge, in vitro displacement of thyroid hormone thyroxine (T4) from the thyroid hormone transport protein thransthyretin by sediment extracts was observed, indicating the presence of compounds potentially able to disrupt T4 plasma transport processes. Antiestrogenic activity was also observed in sediment. The present study showed the occurrence of endocrine-disrupting potencies in sediments from the Dutch delta and the suitability of the ER- and DR-CALUX bioassays to direct endocrine-disruption TIE studies.
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