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Victor Wepener - One of the best experts on this subject based on the ideXlab platform.
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oxygen consumption rate of caenorhabditis elegans as a high throughput endpoint of toxicity testing using the seahorse xfe96 extracellular flux analyzer
Scientific Reports, 2020Co-Authors: G Du Preez, M Daneel, G Engelbrecht, H Miller, C Ricci, Hendrika Fourie, Michal Zouhar, Sebastian Hoss, Victor WepenerAbstract:Caenorhabditis elegans presents functioning, biologically relevant phenotypes and is frequently used as a bioindicator of toxicity. However, most C. elegans in vivo Effect-Assessment methods are laborious and time consuming. Therefore, we developed a novel method to measure the oxygen consumption rate of C. elegans as a sublethal endpoint of toxicity. This protocol was tested by exposing 50 larval stage one C. elegans individuals for 48 h (at 20 °C) to different concentrations of two toxicants i.e. benzylcetyldimethylammonium chloride (BAC-C16) and cadmium (Cd). Following exposures, the oxygen consumption rate of the C. elegans individuals were measured using the high-throughput functionality of the Seahorse XFe96 Extracellular Flux Analyzer. Dose-response curves for BAC-C16 (R2 = 0.93; P = 0.001) and Cd (R2 = 0.98; P = 0.001) were created. Furthermore, a strong, positive correlation was evidenced between C. elegans oxygen consumption rate and a commonly used, ecologically relevant endpoint of toxicity (growth inhibition) for BAC-C16 (R2 = 0.93; P = 0.0001) and Cd (R2 = 0.91; P = 0.0001). The data presented in this study show that C. elegans oxygen consumption rate can be used as a promising functional measurement of toxicity.
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oxygen consumption rate of caenorhabditis elegans as a high throughput endpoint of toxicity testing using the seahorse xf e 96 extracellular flux analyzer
Scientific Reports, 2020Co-Authors: G Du Preez, M Daneel, G Engelbrecht, H Miller, C Ricci, Hendrika Fourie, Michal Zouhar, Sebastian Hoss, Victor WepenerAbstract:Caenorhabditis elegans presents functioning, biologically relevant phenotypes and is frequently used as a bioindicator of toxicity. However, most C. elegans in vivo Effect-Assessment methods are laborious and time consuming. Therefore, we developed a novel method to measure the oxygen consumption rate of C. elegans as a sublethal endpoint of toxicity. This protocol was tested by exposing 50 larval stage one C. elegans individuals for 48 h (at 20 °C) to different concentrations of two toxicants i.e. benzylcetyldimethylammonium chloride (BAC-C16) and cadmium (Cd). Following exposures, the oxygen consumption rate of the C. elegans individuals were measured using the high-throughput functionality of the Seahorse XFe96 Extracellular Flux Analyzer. Dose-response curves for BAC-C16 (R2 = 0.93; P = 0.001) and Cd (R2 = 0.98; P = 0.001) were created. Furthermore, a strong, positive correlation was evidenced between C. elegans oxygen consumption rate and a commonly used, ecologically relevant endpoint of toxicity (growth inhibition) for BAC-C16 (R2 = 0.93; P = 0.0001) and Cd (R2 = 0.91; P = 0.0001). The data presented in this study show that C. elegans oxygen consumption rate can be used as a promising functional measurement of toxicity.
Michal Zouhar - One of the best experts on this subject based on the ideXlab platform.
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oxygen consumption rate of caenorhabditis elegans as a high throughput endpoint of toxicity testing using the seahorse xfe96 extracellular flux analyzer
Scientific Reports, 2020Co-Authors: G Du Preez, M Daneel, G Engelbrecht, H Miller, C Ricci, Hendrika Fourie, Michal Zouhar, Sebastian Hoss, Victor WepenerAbstract:Caenorhabditis elegans presents functioning, biologically relevant phenotypes and is frequently used as a bioindicator of toxicity. However, most C. elegans in vivo Effect-Assessment methods are laborious and time consuming. Therefore, we developed a novel method to measure the oxygen consumption rate of C. elegans as a sublethal endpoint of toxicity. This protocol was tested by exposing 50 larval stage one C. elegans individuals for 48 h (at 20 °C) to different concentrations of two toxicants i.e. benzylcetyldimethylammonium chloride (BAC-C16) and cadmium (Cd). Following exposures, the oxygen consumption rate of the C. elegans individuals were measured using the high-throughput functionality of the Seahorse XFe96 Extracellular Flux Analyzer. Dose-response curves for BAC-C16 (R2 = 0.93; P = 0.001) and Cd (R2 = 0.98; P = 0.001) were created. Furthermore, a strong, positive correlation was evidenced between C. elegans oxygen consumption rate and a commonly used, ecologically relevant endpoint of toxicity (growth inhibition) for BAC-C16 (R2 = 0.93; P = 0.0001) and Cd (R2 = 0.91; P = 0.0001). The data presented in this study show that C. elegans oxygen consumption rate can be used as a promising functional measurement of toxicity.
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oxygen consumption rate of caenorhabditis elegans as a high throughput endpoint of toxicity testing using the seahorse xf e 96 extracellular flux analyzer
Scientific Reports, 2020Co-Authors: G Du Preez, M Daneel, G Engelbrecht, H Miller, C Ricci, Hendrika Fourie, Michal Zouhar, Sebastian Hoss, Victor WepenerAbstract:Caenorhabditis elegans presents functioning, biologically relevant phenotypes and is frequently used as a bioindicator of toxicity. However, most C. elegans in vivo Effect-Assessment methods are laborious and time consuming. Therefore, we developed a novel method to measure the oxygen consumption rate of C. elegans as a sublethal endpoint of toxicity. This protocol was tested by exposing 50 larval stage one C. elegans individuals for 48 h (at 20 °C) to different concentrations of two toxicants i.e. benzylcetyldimethylammonium chloride (BAC-C16) and cadmium (Cd). Following exposures, the oxygen consumption rate of the C. elegans individuals were measured using the high-throughput functionality of the Seahorse XFe96 Extracellular Flux Analyzer. Dose-response curves for BAC-C16 (R2 = 0.93; P = 0.001) and Cd (R2 = 0.98; P = 0.001) were created. Furthermore, a strong, positive correlation was evidenced between C. elegans oxygen consumption rate and a commonly used, ecologically relevant endpoint of toxicity (growth inhibition) for BAC-C16 (R2 = 0.93; P = 0.0001) and Cd (R2 = 0.91; P = 0.0001). The data presented in this study show that C. elegans oxygen consumption rate can be used as a promising functional measurement of toxicity.
G Du Preez - One of the best experts on this subject based on the ideXlab platform.
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oxygen consumption rate of caenorhabditis elegans as a high throughput endpoint of toxicity testing using the seahorse xfe96 extracellular flux analyzer
Scientific Reports, 2020Co-Authors: G Du Preez, M Daneel, G Engelbrecht, H Miller, C Ricci, Hendrika Fourie, Michal Zouhar, Sebastian Hoss, Victor WepenerAbstract:Caenorhabditis elegans presents functioning, biologically relevant phenotypes and is frequently used as a bioindicator of toxicity. However, most C. elegans in vivo Effect-Assessment methods are laborious and time consuming. Therefore, we developed a novel method to measure the oxygen consumption rate of C. elegans as a sublethal endpoint of toxicity. This protocol was tested by exposing 50 larval stage one C. elegans individuals for 48 h (at 20 °C) to different concentrations of two toxicants i.e. benzylcetyldimethylammonium chloride (BAC-C16) and cadmium (Cd). Following exposures, the oxygen consumption rate of the C. elegans individuals were measured using the high-throughput functionality of the Seahorse XFe96 Extracellular Flux Analyzer. Dose-response curves for BAC-C16 (R2 = 0.93; P = 0.001) and Cd (R2 = 0.98; P = 0.001) were created. Furthermore, a strong, positive correlation was evidenced between C. elegans oxygen consumption rate and a commonly used, ecologically relevant endpoint of toxicity (growth inhibition) for BAC-C16 (R2 = 0.93; P = 0.0001) and Cd (R2 = 0.91; P = 0.0001). The data presented in this study show that C. elegans oxygen consumption rate can be used as a promising functional measurement of toxicity.
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oxygen consumption rate of caenorhabditis elegans as a high throughput endpoint of toxicity testing using the seahorse xf e 96 extracellular flux analyzer
Scientific Reports, 2020Co-Authors: G Du Preez, M Daneel, G Engelbrecht, H Miller, C Ricci, Hendrika Fourie, Michal Zouhar, Sebastian Hoss, Victor WepenerAbstract:Caenorhabditis elegans presents functioning, biologically relevant phenotypes and is frequently used as a bioindicator of toxicity. However, most C. elegans in vivo Effect-Assessment methods are laborious and time consuming. Therefore, we developed a novel method to measure the oxygen consumption rate of C. elegans as a sublethal endpoint of toxicity. This protocol was tested by exposing 50 larval stage one C. elegans individuals for 48 h (at 20 °C) to different concentrations of two toxicants i.e. benzylcetyldimethylammonium chloride (BAC-C16) and cadmium (Cd). Following exposures, the oxygen consumption rate of the C. elegans individuals were measured using the high-throughput functionality of the Seahorse XFe96 Extracellular Flux Analyzer. Dose-response curves for BAC-C16 (R2 = 0.93; P = 0.001) and Cd (R2 = 0.98; P = 0.001) were created. Furthermore, a strong, positive correlation was evidenced between C. elegans oxygen consumption rate and a commonly used, ecologically relevant endpoint of toxicity (growth inhibition) for BAC-C16 (R2 = 0.93; P = 0.0001) and Cd (R2 = 0.91; P = 0.0001). The data presented in this study show that C. elegans oxygen consumption rate can be used as a promising functional measurement of toxicity.
T C M Brock - One of the best experts on this subject based on the ideXlab platform.
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is the Effect Assessment approach for fungicides as laid down in the european food safety authority aquatic guidance document sufficiently protective for freshwater ecosystems
Environmental Toxicology and Chemistry, 2019Co-Authors: Andreu Rico, T C M Brock, Michiel A DaamAbstract:In Europe, the European Food Safety Authority aquatic guidance document describes the procedures for the derivation of regulatory acceptable concentrations (RACs) for pesticides in edge-of-field surface waters on the basis of tier-1 (standard test species), tier-2 (geometric mean and species sensitivity distributions [SSDs]), and tier-3 (model ecosystem studies) approaches. In the present study, the protectiveness of such a tiered approach was evaluated for fungicides. Acute and chronic RACs for tier-1 and tier-2B (SSDs) were calculated using toxicity data for standard and additional test species, respectively. Tier-3 RACs based on ecological thresholds (not considering recovery) could be derived for 18 fungicides. We show that tier-1 RACs, in the majority of cases, are more conservative than RACs calculated based on model ecosystem experiments. However, acute tier-2B RACs do not show a sufficient protection level compared with tier-3 RACs from cosm studies that tested a repeated pulsed exposure regime or when relatively persistent compounds were tested. Chronic tier-2B RACs showed a sufficient protection level, although they could only be evaluated for 6 compounds. Finally, we evaluated the suitability of the calculated RACs for 8 compounds with toxicity data for fungi. The comparison shows that the current RACs for individual fungicides, with a few exceptions (e.g., tebuconazole), show a sufficient protection level for structural and functional fungal endpoints. However, more data are needed to extend this comparison to other fungicides with different modes of action. Environ Toxicol Chem 2019;38:2279-2293. © 2019 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.
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Effects of sediment spiked lufenuron on benthic macroinvertebrates in outdoor microcosms and single species toxicity tests
Aquatic Toxicology, 2016Co-Authors: T C M Brock, J. Dick M. Belgers, M C Boerwinkel, Michiel H S Kraak, Jan Arie Vonk, Derek A. Bas, L Bibbe, Steven J H Crum, Noel J Diepens, Ivo RoessinkAbstract:Sediment ecotoxicity studies were conducted with lufenuron to (i) complement the results of a water-spiked mesocosm experiment with this lipophilic benzoylurea insecticide, (ii) to explore the predictive value of laboratory single-species tests for population and community-level responses of benthic macroinvertebrates, and (iii) to calibrate the tier-1 Effect Assessment procedure for sediment organisms. For this purpose the concentration-response relationships for macroinvertebrates between sediment-spiked microcosms and those of 28-d sediment-spiked single-species toxicity tests with Chironomus riparius, Hyalella azteca and Lumbriculus variegatus were compared. Lufenuron persisted in the sediment of the microcosms. On average, 87.7% of the initial lufenuron concentration could still be detected in the sediment after 12 weeks. Overall, benthic insects and crustaceans showed treatment-related declines and oligochaetes treatment-related increases. The lowest population-level NOEC in the microcosms was 0.79 μg lufenuron/g organic carbon in dry sediment (μg a.s./g OC) for Tanytarsini, Chironomini and Dero sp. Multivariate analysis of the responses of benthic macroinvertebrates revealed a community-level NOEC of 0.79 μg a.s./g OC. The treatment-related responses observed in the microcosms are in accordance with the results of the 28-d laboratory toxicity tests. These tests showed that the insect C. riparius and the crustacean H. azteca were approximately two orders of magnitude more sensitive than the oligochaete L. variegatus. In our laboratory tests, using field-collected sediment, the lowest 28-d EC10 (0.49 μg a.s./g OC) was observed for C. riparius (endpoint survival), while for the standard OECD test with this species, using artificial sediment, a NOEC of 2.35 μg a.s./g OC (endpoint emergence) is reported. In this particular case, the sediment tier-1 Effect Assessment using the chronic EC10 (field-collected sediment) or chronic NOEC (artificial sediment) of C. riparius and an Assessment factor of 10, seems to be protective for the treatment-related responses observed in the sediment-spiked microcosms.
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priorities to improve the ecological risk Assessment and management for pesticides in surface water
Integrated Environmental Assessment and Management, 2013Co-Authors: T C M BrockAbstract:This article deals with prospective and retrospective ecological risk Assessment (ERA) procedures for pesticides in surface waters as carried out under European legislation (Regulation 1107/2009/EC; Directive 2009/128/EC; Directive 2000/60/EC). Priorities to improve the aquatic risk Assessment and management of pesticides are discussed on basis of the following 5 theses: 1) the management of the environmental risks of pesticides in surface water requires an appropriate implementation of feedback mechanisms between prospective and retrospective ERA, 2) an appropriate ERA cannot be carried out without well-defined specific protection goals, described in terms of focal vulnerable populations and related exposure Assessment goals, 3) the interaction between the Assessment of exposure and eco(toxico)logical Effects in ERA is at a lower level of sophistication than either Assessment of exposure or Assessment of Effects in the field, 4) there is insufficient experimental proof that, in prospective ERA, the chronic Effect Assessment procedures accurately predict long-term population- and community-level impacts, and 5) multiple stress by pesticides in aquatic ecosystems cannot be ignored in ERA, but in individual water bodies, toxicity usually is dominated by a limited number of substances. Integr Environ Assess Manag 2013;9:e64–e74.
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acute toxicity tests with daphnia magna americamysis bahia chironomus riparius and gammarus pulex and implications of new eu requirements for the aquatic Effect Assessment of insecticides
Environmental Science and Pollution Research, 2012Co-Authors: T C M Brock, Rene P A Van WijngaardenAbstract:Threshold concentrations for treatment related Effects of 31 insecticides, as derived from aquatic micro-/mesocosm tests, were used to calibrate the predictive value of the European Tier-1 acute Effect Assessment on basis of laboratory toxicity tests with Daphnia magna, Chironomus spp., Americamysis bahia and Gammarus pulex. The acute Tier-1 Effect Assessment on basis of Daphnia (EC50/100) overall was protective for organophosphates, carbamates and most pyrethroids but not for neonicotinoids and the majority of insect growth regulators (IGRs) in the database. By including the 28-day water-spiked Chironomus riparius test, the Effect Assessment improves but selecting the lowest value on basis of the 48-h Daphnia test (EC50/100) and the 28-day Chironomus test (NOEC/10) is not fully protective for 4 out of 23 insecticide cases. An Assessment on basis of G. pulex (EC50/100) is sufficiently protective for 15 out of 19 insecticide cases. The Tier-1 procedure on basis of acute toxicity data (EC50/100) for the combination of Daphnia and A. bahia and/or Chironomus (new EU dossier requirements currently under discussion) overall is protective to pulsed insecticide exposures in micro-/mesocosms. For IGRs that affect moulting, the Effect Assessment on basis of the 48-h Chironomus test (EC50/100) may not always be protective enough to replace that of the water-spiked 28-day C. riparius test (NOEC/10) because of latency of Effects.
Heloise Cadet - One of the best experts on this subject based on the ideXlab platform.
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erratum to site Effect Assessment using kik net data part 1 a simple correction procedure for surface downhole spectral ratios
Bulletin of Earthquake Engineering, 2012Co-Authors: Heloise Cadet, Pierreyves Bard, Adrian RodriguezmarekAbstract:When data is available, the estimation of site Effects is usually performed using the “standard spectral ratio” (SSR) technique with respect to an outcropping, reference rock site. This study uses the Japanese KiK-net network, which has more than 600 pairs of surface-downhole stations allowing the computation of empirical borehole transfer functions, consisting of mean spectral ratios of surface over downhole recordings. The borehole transfer function deviates from the SSR in two respects: the reference is located at depth, and the downhole velocity varies from one site to another. These differences bias the estimation of the transfer function with reference to a standard outcrop rock site. The goal of this paper is to develop a simple and robust methodology to correct for such bias. The proposed correction procedure consists of two steps: a depth correction designed to account, in a simplified and physically acceptable way, for the existence at depth of destructive interferences and the absence of free-surface Effects in the high-frequency range; and an impedance correction designed to normalize the shear wave velocity at depth. The depth correction involves a simple, frequency-dependent curve to be adapted for each site as a function of the first destructive interference frequency at depth. The impedance normalization combines the use of “generic” rock velocity profiles and a quarter-wavelength approach, resulting in a smooth frequency-dependent amplitude correction. The proposed methodology is applied on a large subset of KiK-net data in view of analysing the correlation between site amplification factors and site parameters in a companion paper.
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erratum to site Effect Assessment using kik net data part 2 site amplification prediction equation based on f0 and vsz
Bulletin of Earthquake Engineering, 2012Co-Authors: Heloise Cadet, Pierreyves Bard, Annemarie Duval, Etienne BertrandAbstract:This paper presents empirical correlations between amplification factors and simple site parameters derived from a large subset of the KiK-net data. The amplification factor is estimated from the ratios between the surface and down-hole horizontal response spectra, corrected for the varying depths and impedance of the down-hole sites (Cadet et al. in Site Effect Assessment using KiK-net data—part 1—a simple correction procedure for surface/downhole spectral ratios, 2011). Several site parameters are selected on the basis of their simplicity and availability at relatively low cost. They are the shallow time-average velocities VSZ, with z equal to 5, 10, 20 and 30 m, and the fundamental frequency f0. The amplification factors are then correlated with each of the individual site parameters; four other “twin-parameter”—couples (f0, VSZ)—are also considered and the correlation with amplification factors is performed through a normalization of the frequencies by each site fundamental frequency. The quality of the correlations is given by a misfit compared with the original data variance. The largest variance reduction is obtained with twin-parameter characterizations, out of which the couple (f0, VS30) proves to provide the lower misfit. The performance of single parameter correlations is relatively lower; however, the best single parameter proves to be the fundamental frequency, which provides smaller misfit than the Vsz parameters. A comparison is also performed with the amplification factors recommended in European regulations, showing that it is possible right now to significantly improve both the site characterization criteria and the associated amplification factors, for use in building codes and microzonation studies.