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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Bioassays to Quantify Hygienic Behavior in Honey Bee (Apis Mellifera L.) Colonies : A Review
Leclercq, Gil ; Francis, Frédéric ; Gengler, Nicolas ; Blacquière, Tjeerd - \ 2018
Journal of Apicultural Research 57 (2018). - ISSN 0021-8839 - p. 663 - 673.
Apis mellifera - Ascosphaera apis - bioassays - hygienic behavior - Paenibacillus larvae - Varroa destructor

Individual immunity in honey bees (Apis mellifera L.) is complemented by highly evolved social behaviors. Among them, hygienic behavior has a key role involving the detection and removal of unhealthy or dead brood. Since the 1960s, several bioassays have been developed to quantify the hygienic behavior of honey bee colonies against chalkbrood, American foulbrood, and varroa infested brood. Here, we review the five main bioassays used since the late 1960s. We describe their advantages and disadvantages, including a special focus on their inherent biases. For each assay, we also discuss whether or not their use should be restricted to quantify the hygienic behavior against chalkbrood, or American foulbrood, or varroa infested brood. Overall, the bioassays involving the removal of freeze-killed brood are recommended over the bioassays relying on the removal of pin-killed brood but only for the quantification of hygienic behavior toward chalkbrood and American foulbrood. These bioassays are not recommended to quantify the hygienic behavior toward varroa infested brood, for which an accurate assessment should rely on assays based on the removal of brood artificially infested with varroa mites. Choosing an appropriate bioassay is crucial for an accurate assessment of the hygienic behavior against a defined pathogen, depending on the research question, or the goal of the breeding program. Bioensayos para cuantificar el comportamiento higiénico en las colonias de abejas melíferas (Apis mellifera L.): una revisión La inmunidad individual de las abejas melíferas (Apis mellifera L.) se complementa con comportamientos sociales altamente evolucionados. Entre ellos, el comportamiento higiénico tiene un papel clave en la detección y eliminación de crías enfermas o muertas. Desde la década de 1960, se han desarrollado varios bioensayos para cuantificar el comportamiento higiénico de las colonias de abejas melíferas frente a la cría infestada de Ascosfera, loque americana y varroa. Aquí revisamos los cinco principales bioensayos utilizados desde finales de la década de 1960. Describimos sus ventajas y desventajas, incluyendo un enfoque especial en sus sesgos inherentes. Para cada ensayo, también discutimos si su uso debe ser restringido o no para cuantificar el comportamiento higiénico contra la cría de loque americana o la cría infestada de varroa. En general, los bioensayos que involucran la eliminación de la cría muerta por congelación son más recomendables que los bioensayos que dependen de la eliminación de la cría muerta por pin, pero sólo para la cuantificación del comportamiento higiénico hacia la cría infestada de Ascosfera y la loque americana. Estos bioensayos no se recomiendan para cuantificar el comportamiento higiénico de la cría infestada de varroa, para lo cual una evaluación precisa debe basarse en ensayos basados en la extracción de la cría infestada artificialmente con ácaros de la varroa. La elección de un bioensayo apropiado es crucial para una evaluación precisa del comportamiento higiénico frente a un patógeno definido, dependiendo de la pregunta de investigación o del objetivo del programa de cría.

Biological processes induced by ZnO, Amoxicillin, Rye and Fructooligosaccharides in cultured Intestinal Porcine Epithelial Cells : VDI-4; In-vitro tests 2013-2014
Hulst, M.M. ; Hoekman, A.J.W. ; Wijers, I. ; Schokker, D. ; Smits, M.A. - \ 2015
Wageningen : Wageningen UR Livestock Research (Livestock Research report 882) - 42
in vitro - bioassays - epithelium - livestock - feed additives - genes - immunology - biotesten - epitheel - vee - voedertoevoegingen - genen - immunologie
The objective of this study was to develop an in-vitro bioassay using cultured Intestinal Porcine Epithelial Cells (IPEC-J2) and evaluate the capability of this assay to predict enterocyte-specific physiological and immunological processes induced by nutrients/additives in the intestines of farm animals. Responses to five nutrients/feed-additives, similar to those studied in animal trials, performed in the Feed4Foodure framework, were measured by gene expression analysis of IPEC-J2 cells either under stressed (Salmonella) or non-stressed conditions. Response genes were analysed using bioinformatics web-tools in order to identify dominant biological processes induced by these nutrients/feed-additives and to predict key-genes/proteins important for regulation of these biological proc
Werken aan bodemweerbaarheid
Broek, R.C.F.M. van den; Berg, W. van den; Lamers, J.G. ; Cuijpers, W.J.M. ; Hospers-Brands, A.J.T.M. ; Smits, S. - \ 2014
Praktijkonderzoek Plant & Omgeving B.V. - 63
teeltsystemen - bodemweerbaarheid - bestrijdingsmethoden - agrarische bedrijfsvoering - phytophthora cactorum - bodemeigenschappen - gewasbescherming - proeven - biotesten - fragaria - biologische technieken - vollegrondsteelt - cropping systems - soil suppressiveness - control methods - farm management - soil properties - plant protection - trials - bioassays - biological techniques - outdoor cropping
De land- en tuinbouw ontwikkelt zich in de richting van steeds intensievere en complexere bedrijfssystemen. Vanuit de sector groeit het besef dat de chemische benadering van ziekten en plagen haar grenzen begint te bereiken. Ook de consument verlangt van de producent dat de inzet van chemische middelen gereduceerd wordt en gezocht wordt naar andere, meer duurzame oplossingen. Een van de oplossingsrichtingen is het creëren van een gezonde, veerkrachtige en weerbare bodem. Op zulke bodems groeit een gezond gewas met een goede opbrengst die minder gevoelig is voor ziekten en plagen en efficiënter omgaat met nutriënten waardoor er minder verliezen optreden. Hierdoor hoeven telers minder gewasbeschermingsmiddelen en nutriënten te gebruiken en kunnen ze, met een beter inkomen, milieuvriendelijker telen. Aardbei is een voorbeeld van een zeer intensieve teelt, die erg gevoelig is voor ziekten en plagen. In de teelt worden relatief veel gewasbeschermingsmiddelen gebruikt, en er is een sterke behoefte aan kennis die de inzet van deze middelen kan beperken. Aardbei is ook een heel geschikt toetsgewas, omdat het sterk reageert op de bodemgezondheid van een perceel. Is deze goed dan ligt de aardbeienproductie veel hoger dan op percelen waarop de bodemgezondheid matig of slecht is. Opbrengstverschillen kunnen oplopen tot meer dan 50%. De verkregen resultaten bij aardbei kunnen ook vertaald worden naar andere vollegronds gewassen.
Screening van hot spots van nieuwe verontreinigingen : een pilot studie in bodem, grondwater en oppervlaktewater
Lahr, J. ; Laak, T.L. ter; Derksen, A. - \ 2014
Wageningen : Alterra (Alterra-rapport 2538) - 87
bodemverontreiniging - waterverontreiniging - verontreinigende stoffen - toxicologie - geneesmiddelen - ecologische risicoschatting - biotesten - inventarisaties - soil pollution - water pollution - pollutants - toxicology - drugs - ecological risk assessment - bioassays - inventories
Onder nieuwe verontreinigingen verstaan we stoffen die nog niet of niet volledig zijn gereguleerd en waarvan de milieurisico’s vaak onbekend zijn. Daarbij gaat het om stoffen als natuurlijke hormonen en hormoonverstorende stoffen (weekmakers, detergenten, brandvertragers, e.d.), humane geneesmiddelen, diergeneesmiddelen, nanodeeltjes en microplastics. In de ‘waterwereld’ is altijd meer aandacht besteed aan de nieuwe verontreinigingen dan binnen andere beleidsvelden. In de bodem zijn de aanwezigheid en de mogelijke risico’s grotendeels onbekend. In 2013 heeft een consortium van diverse onderzoeksinstanties en stakeholders een pilotonderzoek uitgevoerd naar de aanwezigheid en mogelijke risico’s van hormonen en geneesmiddelen in het systeem bodem - grondwater - oppervlaktewater.
GM1-derived carbohydrates for pathogen and antibody detection : synthesis and biological evaluation
Garcia Hartjes, J. - \ 2014
Wageningen University. Promotor(en): Han Zuilhof, co-promotor(en): Tom Wennekes. - Wageningen : Wageningen University - ISBN 9789462571273 - 240
koolhydraten - moleculaire detectie - antilichamen - pathogenen - remmers - biotesten - carbohydrates - molecular detection - antibodies - pathogens - inhibitors - bioassays
Towards a realistic risk characterization of complex mixtures using in vitro bioassays
Montano Garces, M. - \ 2013
Wageningen University. Promotor(en): Tinka Murk, co-promotor(en): A.C. Gutleb. - [S.l.] : s.n. - ISBN 9789461736598
risicoschatting - persistente organische verontreinigende stoffen - verontreinigde sedimenten - mengsels - biotesten - in vitro - toxiciteit - schildklierhormonen - risk assessment - persistent organic pollutants - contaminated sediments - mixtures - bioassays - in vitro - toxicity - thyroid hormones

This thesis aims to better understand and further improve the relevance and reliabilityof in vitro bioassaysfor a biobased risk characterisation of complex mixtures, with special focus on persistent organic pollutants (POPs) in sediments.

In Chapter 1 the importance of complex mixture characterization in modern society is introduced. The methods available, their current advantages and their disadvantages for complex mixture testing are described. With the shift from policy oriented chemical testing towards the inclusion of in vitro bioanalysis, important challenges have to be overcome to ensure a relevant and reliable quantification of the toxic potency of complex mixtures. These challenges are explained in the introduction, including the status of development and validation of those aspects for reliable testing. One of the main advantages that in vitro bioanalysis has to offer is the possibility to quantify the toxic potency of compounds for which chemical analytical methods have not or hardly been developed, for example because standards do not yet exist. Hydroxylated metabolites of POPs are an example of a toxicologically relevant group of compounds that can exert endocrine disrupting effects, but they cannot yet be routinely analysed. A selection of yet unsolved issues are further studied and discussed in this thesis, as outlined in the “approach and structure of the thesis”.

In Chapter 2 a meta-analysis is performed to study the occurrence and relevance of hydroxylated (OH) compounds in humans and wildlife. Reported body burdens of halogenated phenolic contaminants (HPCs), including OH-POP in different tissues from humans and wildlife species, are reviewed in relation to the concentration of their putative parent compounds to be able to reveal relevant exposure routes and sub-populations at risk. Highest OH-POP levels were found in blood plasma, and highly perfused and fetal tissues. Plasma concentrations of analysed known HPCs ranged from 0.1-100 nM in humans and up to 240, 454, 800 and 7650 nM for birds, fish, cetaceans and other mammals, respectively. Reported metabolite blood plasma levels also are compared with relevant toxicological threshold concentrations from toxicological studies, and appeared to fully fall within the in vitro (0.05–10000 nM) and in vivo (3-940 nM) effect concentrations reported for OH-POPs. Given the sensitivity of early developmental stages, and information lacking about the general population, it is advisable to determine HPC background blood levels in children and fetal tissue .

Given the toxicological relevance of the OH-POPs, Chapter 3 aims at providing solutions to the long standing problem of the in vitro production and analysis of OH-POP metabolite thyroid hormone disrupting (THD) potency via binding to plasma thyroid hormone binding proteins (THBPs). In sediments and for example seafood, the POPs occur as parent compounds that would only become THD after metabolisation (hydroxylation). Several methods have shown the competitive thyroxine (T4) T4 displacement potency of pure metabolites. However, in vitro metabolization of, among others, polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers(PBDEs) followed by in vitro quantification of their potency has encountered drawbacks related to the co-extraction of compounds disturbing the T4-TTR competitive binding assay. The present study identifies and quantifies the major co-extractants, cholesterol and saturated and non-saturated fatty acids (SFA and NSFA), at levels above 20 μM (20 nmol per mg protein in the incubation mixture) following various extraction methods. A new method is presented to in vitro metabolise parent compounds into OH-metabolites followed by selective extraction of metabolites while four-fold reducing co-extraction of the disturbing compounds. In addition a microplate-format non-radioactive fluorescence displacement assay was developed to quantify the TTR binding potency of the metabolites formed. The effectiveness of the in vitro metabolism and extraction of the OH-metabolites of the model compounds CB 77 and BDE 47 was chemically quantified with a newly developed chromatographic method analyzing silylated derivatives of the OH-metabolites and co-extractants. Due to the mentioned improvements, it is now possible to make a dose-response curve up to 50% inhibition with OH-metabolites extracted from bioactivated CB 77 and BDE 47. Without taking the toxic potencies of bio-activated POPs into account with bioanalysis, the hazard and risk posed by POPs will be seriously underestimated.

The chapters 4 and 5 are committed to tackle the issues of supramaximal (SPMX) responses and sample extract concentration which are crucial to reliably quantify of the toxic potencies of complex mixtures with in vitro bioassays.

A SPMX effect is the phenomenon that compounds induce a maximum response in an assay that is significantly higher than that of the positive control. As the positive control is used to quantify the toxic potency of a sample, this could result in over-estimation of its toxic potency. As this has been most elaborately reported for in vitro estrogenicity assays, a meta-analysis was performed of such assays, compounds and conditions in which the effect is observed (Chapter 4a).For the 21 natural and industrial chemicals that could be identified as SPMX inducers, the culture and exposure conditions varied greatly among and between the assays. Relevant information on assay characteristics, however, sometimes lacked. Diethylstilbestrol (DES), genistein (GEN) and bisphenol A (BPA) were selected to build a database. The meta-analysis revealed that the occurrence of SPMX effects, could be related to a number of specific assay characteristics: 1) the type and concentration of the serum used to supplement the exposure medium; 2) the endpoint used to quantify the estrogenic potency (endogenous or transfected reporter gene), 3) the number of EREs (estrogen responsive elements) used before the reporter gene, and 4) the nature of the promoter’s. There were no indications that solvent concentration in culture, exposure period or cell model influenced the occurrence of SPMX. It is important to understand the mechanism behind this phenomenon because in vitro assays for estrogenicity are used extensively to characterize and quantify the estrogenic potency of compounds, mixtures and environmental extracts.

Several SPMX inducers also have been reported to block cellular efflux pumps in vivo and in vitro (Anselmo et al. 2012; Georgantzopoulou et al. 2013). Therefore it was hypothesized that efflux pump blockers present in environmental matrices could increase the internal concentration of bioassay agonists and thus cause the SPMX. In Chapter 4b this hypothesis was tested by adapting a 96-well plate cellular efflux pump inhibition assay (CEPIA) to the H4IIE rat hepatoma cell line used for the DR.Luc reporter gene assay for dioxin-like compounds. The influence of various environmentally relevant efflux pump inhibitors on the 2,3,7,8-tetrachlorodibenzo-p-dioxine (TCDD) response was tested. Under the DR.Luc assay conditions there was no evidence that P-gp efflux pump inhibitors modified or potentiated the activity of TCDD. Neither genistein nor quercetin, two potent SPMX inducers on ER-mediated assays, induced any signal on the DR.Luc assay, nor influenced the luciferase induction by TCDD. Future work should be focused on testing the consequences of efflux pump inhibition with an AhR-agonist which is a P-gp substrate, as this could result in intracellular accumulation of this AhR-agonist.

It is standard practice to use a high single stock concentration of extracts to further dilute test concentrations from and perform the analysis. However, a high contaminant load in an extract may oversaturate the solubility of the extracted compounds in carrier solvents and overload the clean-up columns which may reduce the efficiency of polyaromatic hydrocarbons (PAHs) elimination from the extract. These problems may cause respectively under- or over-estimation of the quantified dioxin-like toxic potency. Therefore Chapter 5 focuses on the effects of initial stock concentrations, including sonication assisted dissolution and exposure time, on the quantified dioxin-like potency of cleaned nonpolar sediment extracts. Indeed, more than 20 g sediment equivalents (SEQ)/mL DMSO) as initial stock concentrations resulted in underestimation of bio-TEQ levels in the sediments as observed for cleaned nonpolar sediment extracts from various locations in Luxembourg. An overload of extract on clean-up columns caused an over-estimation of the dioxin-like potency at 24 hours of exposure, probably due to limited removal of PAHs that can induce false positive responses in the in vitro assays. Sonication assisted dissolution of the stock before serial dilution strongly reduced the standard variation of the outcomes. Taking into account the aspects revealed in this study, in addition to already described important issues for quality control, the in vitro bioassays based 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. For the generally applied sediment quality criteria, advices are given about maximum initial stock concentrations to achieve reliable bioassay outcomes.

The methods and concepts developed for metabolic activation of compounds in non-polar sediment extracts and in in vitro analysis of the TTR-competitive binding are applied in Chapter 6 to extracts from highly or less contaminated sediments collected in Luxembourg. Nonpolar fractions of sediment extracts 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 non-radioactive 96-well plate transthyretin (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). Without bioactivation, medium polar and polar fractions also contained potent TTR-binding compounds with potencies from 1.6 to 17 nmol T4-Eq/g SEQ. This demonstrates that a more realistic in vitro sediment THD risk characterization should also include testing ofboth polar and medium polar sediment extracts for THD, as well as bioactivated nonpolar sediment fractions. Without bioactivation THD potency is not observed in nonpolar sediment extracts, although in in vivo experiments PCBs and PBDEs, and not with dioxins or PAHs, have shown to be thyroid hormone disrupting (THD), demonstrating this bio-activation is toxicologically relevant and therefore required for sediment hazard characterisation.

Chapter 7 discusses the implications of our results to improve the relevance and reliability of in vitro bioassay applied for risk characterisation of complex mixtures from sediments and other matrices. The evidence obtained to support the relevance of POP bio-activation is considered both from the exposure perspective as well as the toxicity perspective. Various features of the newly developed methods and knowledge acquired within this PhD project are discussed in relation to in vitro bioassay risk characterization of sediments towards a realistic in vitro bioassay-based risk characterization of complex mixtures. Some important aspects for the inclusion of metabolizing systems within in vitro bioassay are discussed. In addition, alternatives to deal with the SPMX effect and the definition of suitable sample amounts to improve in vitro bioassay reliability are offered. The suitability of the developed approach application is considered for the risk characterization of sediments. Furthermore, an analysis is made to decide whether this thesis have made in vitro bioassays more reliable and relevant for risk characterization of complex mixtures. Finally, it provides some concluding remarks and aspects for further applications and research.

Rododendron spoort Phytophthora op
Evenhuis, A. - \ 2012
phytophthora - aardbeien - fruitteelt - kleinfruit - biotesten - gewasbescherming - water - pythium - strawberries - fruit growing - small fruits - bioassays - plant protection
Poster met onderzoeksinformatie. In dit onderzoek worden blaadjes van Rododendron gebruikt om Phytophthora aan te tonen in water dat gebruikt wordt voor de aardbeienteelt.
Screening for Modulatory Effects on Steroidogenesis Using the Human H295R Adrenocortical Cell Line: A Metabolomics Approach
Rijk, J.C.W. ; Peijnenburg, A.A.C.M. ; Blokland, M.H. ; Lommen, A. ; Hoogenboom, L.A.P. ; Bovee, T.F.H. - \ 2012
Chemical Research in Toxicology 25 (2012)8. - ISSN 0893-228X - p. 1720 - 1731.
mass-spectrometry - in-vitro - expression - receptor - assay - disruption - inhibitors - chemicals - bioassays - model
The recently OECD validated H295R steroidogenesis assay provides an in vitro alternative to evaluate the potential interference of exogenous compounds with endogenous steroid hormone synthesis. Currently, this assay is used for a simple negative-positive screening of compounds using testosterone and estradiol levels as end points, measured with specific enzyme immunoassays (EIAs) or targeted liquid chromatography (LC) and gas chromatography (GC)–mass spectrometry (MS) methods. However, recent developments in LC-MS and bioinformatics allow for more comprehensive approaches to evaluate changes in steroid profiles. In the current work, the H295R cell model was combined with a metabolomics approach to monitor changes in metabolite profiles in both a targeted and untargeted way. H295R cells were exposed for 48 h to model compounds, i.e., forskolin, abiraterone, prochloraz, ketoconazole, trilostane, formestane, aminoglutethimide, fadrozole, etomidate, and metyrapone, known to affect steroidogenesis. After exposure, the levels of 9 natural steroids were determined by a quantitative targeted GC-MS/MS method and compared to a metabolomics method using Ultra Performance Liquid Chromatography–Time-of-Flight–Mass Spectrometry (UPLC-ToF-MS). Like the EIAs, both methods were suited for negative-positive screening, but the MS methods also generated specific fingerprints, allowing chemical class prediction of the compound under investigation. Although the targeted GC-MS/MS was more sensitive, which was an advantage regarding analysis of the estrogens 17ß-estradiol and estrone, the untargeted UPLC-ToF-MS was able to evaluate effects on the synthesis of the corticosteroids. Moreover, untargeted comparison of the aligned chemical profiles allowed identification of all m/z-values that are differential between exposed and nonexposed H295R cells. In conclusion, application of a comprehensive metabolite profiling methodology not only provides a tool to screen compounds for steroidogenic modulating properties, but also allows chemical class prediction. As such, steroid profiling methodologies in conjunction with the H295R assay can contribute to the prioritization of chemicals for additional safety testing.
Development and validation of in vitro bioassays for thyroid hormone receptor mediated endocrine disruption
Freitas, J. de - \ 2012
Wageningen University. Promotor(en): Tinka Murk; Ivonne Rietjens, co-promotor(en): J.D. Furlow. - [S.l.] : s.n. - ISBN 9789461734372 - 192
hormoonverstoorders - biotesten - in vitro - schildklierhormonen - endocrine disruptors - bioassays - in vitro - thyroid hormones

Thyroid hormones regulate crucial processes in vertebrates such as reproduction, development and energy metabolism. Endocrine disruption via the thyroid hormone system is gaining more attention both from scientists and regulators, because of the increasing incidence of hormone-related cancers and developmental defects, and the requirement that newly marketed compounds are tested for thyroid hormone disruption. To reduce the number of experimental animals used and to increase the insight into the mechanisms of toxic interference with the thyroid hormone receptor function, we developed and validated functional in vitro bioassays for thyroid hormone receptor-mediated toxicity. These assays enable quick identification and quantification of specific thyroid hormone receptor disrupting potency of compounds and contribute to the further establishment of a battery of in vitro tests for hazard identification of thyroid active compounds.

Gewasbeschermingsmiddelen, waterkwaliteit en risicobeoordeling bij toelating
Brock, T.C.M. - \ 2012
Gewasbescherming 43 (2012)4. - ISSN 0166-6495 - p. 112 - 117.
oppervlaktewater - pesticiden - waterverontreiniging - landbouw - ecotoxicologie - biotesten - kwaliteitsnormen - toelating van bestrijdingsmiddelen - besluitvorming - surface water - pesticides - water pollution - agriculture - ecotoxicology - bioassays - quality standards - authorisation of pesticides - decision making
Eén van de doelstellingen van het toelatingsbeleid van gewasbeschermingsmiddelen is te voorkomen dat, na goede landbouwkundige toepassing, deze middelen en hun omzettingsproducten een schadelijke uitwerking hebben op waterorganismen. Het kan verbazing wekken dat in watergangen de waterkwaliteitsnormen voor gewasbeschermingsmiddelen nog regelmatig overschreden worden, daar een strikt omschreven toelatingsbeleid is geïmplementeerd en diverse technische maatregelen zijn genomen om emissie van gewasbeschermingsmiddelen naar oppervlaktewater te voorkomen (o.a. drift reducerende sproeidoppen; bufferzones). Er wordt door sommigen geopperd dat het toelatingsbeleid niet geheel voldoet. Reden genoeg om nader in te gaan op recente ontwikkelingen bij de aquatische risicobeoordeling van gewasbeschermingsmiddelen in het kader van de toelating.
Nematoden als indicator voor de waterkwaliteit
Sollie, S. ; Kluck, J. ; Hooff, A. van; Helder, J. - \ 2012
H2O : tijdschrift voor watervoorziening en afvalwaterbehandeling 45 (2012)14/15. - ISSN 0166-8439 - p. 48 - 50.
waterkwaliteit - oppervlaktewater - biologische monitoring - waterbodems - nematoda - biotesten - water quality - surface water - biomonitoring - water bottoms - bioassays
Het beoordelen van de waterkwaliteit is een lastige zaak. Vaak wordt de chemische kwaliteit bepaald, maar eigenlijk willen we weten welke effecten die heeft op de biologische kwaliteit. Veld- en microscopisch onderzoek aan biologische indicatoren is bewerkelijk en bovendien zijn de resultaten niet eenduidig. Met de ontwikkeling van DNA-analysetechnieken is het mogelijk geworden nematoden in de waterbodem snel en accuraat te analyseren. Nematoden zijn kleine aaltjes (lengte 0,3 tot 1,0 mm) die in grote aantallen en met een aanzienlijke diversiteit in de waterbodem aanwezig zijn. De combinatie van hoge dichtheden en grote verscheidenheid maakt de nematodengemeenschap tot potentiële bio-indicator voor de waterkwaliteit. Een pilot liet zien dat DNA-analyse van nematoden in de waterbodem duidelijke signalen van eutrofiëring aangaf en daarmee inzicht gaf in de waterkwaliteit.
Maximale opsporingskans voor Meloidogyne chitwoodi
Beers, T.G. van; Gastel-Topper, A.W.W. van - \ 2011
actieplan aaltjesbeheersing
meloidogyne chitwoodi - biotesten - aardappelen - bodemonderzoek - bemonsteren - akkerbouw - bioassays - potatoes - soil testing - sampling - arable farming
Brochure over het opsporen van Meloidogyne chitwoodi met behulp van een biotoets.
Geringe besmetting goed zelf op te sporen
Gastel-Topper, A.W.W. van; Korthals, G.W. - \ 2011
Boerderij/Akkerbouw 97 (2011)11. - ISSN 0169-0116 - p. E14 - E15.
meloidogyne chitwoodi - biotesten - plantenparasitaire nematoden - bodempathogenen - bodemonderzoek - akkerbouw - aardappelen - pootaardappelen - bioassays - plant parasitic nematodes - soilborne pathogens - soil testing - arable farming - potatoes - seed potatoes
PPO ontwikkelde een biotoets om Meloidogyne chitwoodi op te sporen. Deze toets doer de teler zelf en geeft meer zekerheid dan een laboratoriumtoets.
Tailored Microarray Platform for the Detection of Marine Toxins
Bovee, T.F.H. ; Hendriksen, P.J.M. ; Portier, L. ; Wang, S. ; Elliott, C.T. ; Egmond, H.P. van; Nielen, M.W.F. ; Peijnenburg, A.A.C.M. ; Hoogenboom, L.A.P. - \ 2011
Environmental Science and Technology 45 (2011)20. - ISSN 0013-936X - p. 8965 - 8973.
harmful algal blooms - human health - shellfish toxins - microplate assay - climate-change - okadaic acid - bioassays - cyanobacteria - yessotoxins - polyether
Currently, there are no fast in vitro broad spectrum screening bioassays for the detection of marine toxins. The aim of this study was to develop such an assay. In gene expression profiling experiments 17 marker genes were provisionally selected that were differentially regulated in human intestinal Caco-2 cells upon exposure to the lipophilic shellfish poisons azaspiracid-1 (AZA1) or dinophysis toxin-1 (DTX1). These 17 genes together with two control genes were the basis for the design of a tailored microarray platform for the detection of these marine toxins and potentially others. Five out of the 17 selected marker genes on this dedicated DNA microarray gave clear signals, whereby the resulting fingerprints could be used to detect these toxins. CEACAM1, DDIT4, and TUBB3 were up-regulated by both AZA1 and DTX1, TRIB3 was up-regulated by AZA1 only, and OSR2 by DTX1 only. Analysis by singleplex qRT-PCR revealed the up- and down-regulation of the selected RGS16 and NPPB marker genes by DTX1, that were not envisioned by the new developed dedicated array. The qRT-PCR targeting the DDIT4, RSG16 and NPPB genes thus already resulted in a specific pattern for AZA1 and DTX1 indicating that for this specific case qRT-PCR might a be more suitable approach than a dedicated array
Development of aquatic biomonitoring models for surface waters used for drinking water supply
Penders, E.J.M. - \ 2011
Wageningen University. Promotor(en): Ivonne Rietjens, co-promotor(en): Gerrit Alink; W. Hoogenboezem. - [S.l.] : S.n. - ISBN 9789461731012 - 176
biologische monitoring - oppervlaktewater - drinkwater - waterkwaliteit - genotoxiciteit - rijn - waterverontreiniging - biotesten - watervoorziening - biomonitoring - surface water - drinking water - water quality - genotoxicity - river rhine - water pollution - bioassays - water supply
Given the need for continued quality control of surface waters used for the production of drinking water by state-of-the-art bioassays and biological early warning systems, the objective of the present thesis was to validate and improve some of the bioassays and biological early warning systems used for quality control of surface water. Although there is a decline in the (geno)toxicity of surface waters over the years as observed for example for the water from the River Rhine over last decades, there is still a need for continued quality control. Due to the lower (geno)toxicity, bioassays with increased sensitivity are needed
Ontwikkeling biotoets voor de detectie van het quarantaineaaltje Meloidogyne chitwoodi : proefuitvoering in de nematodentuin op PPO-AGV, 2010
Gastel, A.W.W. van; Visser, J.H.M. ; Korthals, G.W. - \ 2011
Kennisakker.nl 2011 (2011)16 nov.
plantenparasitaire nematoden - meloidogyne chitwoodi - detectie - biotesten - akkerbouw - pootaardappelen - plant parasitic nematodes - detection - bioassays - arable farming - seed potatoes
Doel van dit onderzoek is het ontwikkelen van een biotoets waarmee lage besmettingen van het quarantaine aaltje M. chitwoodi voorafgaand aan de aardappelteelt betrouwbaar kunnen worden gedetecteerd. Deze toetsmethode wordt ontwikkeld voor gebruik door telers op hun bedrijf en/of in de kas.
Ontwikkeling biotoets voor de detectie van het quarantaineaaltje Meloidogyne chitwoodi : proefuitvoering in de nematodentuin op PPO AGV, 2010
Gastel-Topper, A.W.W. van; Visser, J.H.M. ; Korthals, G.W. - \ 2011
Lelystad : Praktijkonderzoek Plant & Omgeving B.V. - 20
plantenparasitaire nematoden - meloidogyne chitwoodi - biotesten - detectie - akkerbouw - aardappelen - pootaardappelen - plant parasitic nematodes - bioassays - detection - arable farming - potatoes - seed potatoes
De doelstelling van dit onderzoek is het ontwikkelen van een biotoets waarmee lage besmettingen van het quarantaine aaltje Meloidogyne chitwoodi voorafgaand aan de pootaardappelteelt of ander vermeerderingsmateriaal betrouwbaar kunnen worden gedetecteerd, in de grond of door middel van symptomen op een gevoelig gewas, zoals aardappel. Deze toets methode wordt ontwikkeld voor gebruik door telers op hun bedrijf. Voor de biotoets is aardappel als toets gewas gebruikt. Door na het groeiseizoen de aardappelen te beoordelen kan door de mogelijk ontwikkelde symptomen (op de knol) inzicht worden verkregen in de aanwezigheid van Meloidogyne chitwoodi en/of bemonstering van de grond.
Can time-weighted average concentrations be used to assess the risks of metsulfuron-methyl to Myriophyllum spicatum under different time-variable exposure regimes?
Belgers, J.D.M. ; Aalderink, G.H. ; Arts, G.H.P. ; Brock, T.C.M. - \ 2011
Chemosphere 85 (2011)6. - ISSN 0045-6535 - p. 1017 - 1025.
aquatic plants - sulfonylurea herbicides - macrophytes - sensitivity - pesticides - toxicity - bioassays - growth - model
We tested the effects of the herbicide metsulfuron-methyl on growth of the submerged macrophyte Myriophyllum spicatum under laboratory conditions using different exposure scenarios. The exposures of each scenario were comparable in the concentration×time factor, viz., the same 21-d time-weighted average (TWA) concentrations but variable in peak exposure concentrations (ranging from 0.1 to 21000ngaiL(-1)) and exposure periods (1, 3, 7, 14 or 21d). To study recovery potential of the exposed M. spicatum plants we continued the observation on shoot and root growth for another 21d in herbicide-free medium so that the total observation period was 42d. Non-destructive endpoints, length and number of new shoots and roots, were determined weekly from day 14 onwards. Destructive endpoints, dry-weight (DW) of main shoots, new shoots and new roots, were measured at the end of the experiment (t=42d). Metsulfuron-methyl exposure in particular inhibited new tissue formation but was not lethal to main shoots. On days 21 and 42 after start exposure, EC(10)/EC(50) values for new tissues expressed in terms of peak concentration (=measured concentration during exposure periods of different length) showed large differences between exposure scenarios in contrast to EC(10)/EC(50) values for days 21 and 42 expressed in terms of 21-d and 42-d TWA concentrations, respectively. At the end of the experiment (day 42), 42-d TWA EC(x) values were remarkably similar between exposure scenarios, while a similar trend could already be observed on day 21 for 21-d TWA EC(x) values. For the macrophyte M. spicatum and exposure to the herbicide metsulfuron-methyl the TWA approach seems to be appropriate to use in the risk assessment. However, the data from the toxicity experiment suggest that on day 21 also the absolute height of the pulse exposure played a (minor) role in the exposure - response relationships observed
Opheffen groeiremming als onderdeel van emissie-reductie
Maas, Bram van der - \ 2011
cropping systems - closed systems - drainage water - water reuse - greenhouse horticulture - water treatment - bioassays
Nieuwe bacterieziekte lijkt op Xanthomonas: Stenotrophomonas veroorzaker zwarte vaten in radijs
Arkesteijn, M. ; Ludeking, D.J.W. - \ 2011
Onder Glas 8 (2011)5. - p. 59 - 59.
glastuinbouw - radijsjes - bacterieziekten - biotesten - biologische technieken - stenotrophomonas - cultuurmethoden - groenten - greenhouse horticulture - radishes - bacterial diseases - bioassays - biological techniques - stenotrophomonas - cultural methods - vegetables
Sinds 2007 heeft een aantal telers last van een nieuwe ziekte in radijs. Symptomen zijn misvormde knollen, uitval, extra wortelgroei en vooral zwarte vaten in het knolletje. Over de verspreiding is nog weinig bekend. Deze bacterieziekte treedt pleksgewijs op.
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