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.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Food or furniture: Separating trophic and non-trophic effects of Spanish moss to explain its high invertebrate diversity
Borst, Annieke C.W. ; Angelini, Christine ; Berge, Anne ten; Lamers, Leon ; Derksen-Hooijberg, Marlous ; Heide, Tjisse van der - \ 2019
Ecosphere 10 (2019)9. - ISSN 2150-8925
brown food web - detritus - feeding guilds - food provisioning - foundation species - habitat complexity - habitat structure - non-trophic interactions - patch size - species richness - surface area

Foundation species are typically suggested to enhance community diversity non-trophically by increasing habitat structure and mitigating physical stress, while their trophic role is considered of minor importance. Yet, there is little experimental evidence on the relative importance of trophic and non-trophic effects and the interaction with patch size. Here, we transplanted different festoon sizes of living Tillandsia usneoides (Spanish moss) and structural mimics assessing the trophic and non-trophic roles of this habitat-forming epiphyte in mediating the invertebrate community. Compared to bare branches, mimics enhanced species and feeding guild richness and abundances, but living festoons even more so, demonstrating that trophic and non-trophic effects jointly stimulated the community. Specifically, our results show that, independent of patch size, 40% of the total species richness and 46% of total guild richness increase could be contributed to habitat structure alone, while Spanish moss trophically stimulated these metrics by another 60% and 54%. As detritivores were particularly enhanced in living festoons, our findings suggest that trophic stimulation occurred primarily through the provisioning of Spanish moss detritus. Our results highlight that foundation species can facilitate their associated communities through both trophic and non-trophic pathways, calling for studies addressing their indirect trophic role via the brown food web.

Diergeneesmiddelen in het milieu - een synthese van de huidige kennis
Moermond, Caroline ; Lahr, Joost ; Montforts, Mark ; Derksen, Anja ; Bondt, Nico ; Puister-Jansen, Linda ; Koeijer, Tanja de; Hoeksma, Paul - \ 2019
Bilthoven : Rijksinstituut voor Volksgezondheid en Milieu (RIVM) - 15
Diergeneesmiddelen in het milieu : een synthese van de huidige kennis
Lahr, Joost ; Moermond, Caroline ; Montforts, Mark ; Derksen, Anja ; Bondt, Nico ; Puister-Jansen, Linda ; Koeijer, Tanja de; Hoeksma, Paul - \ 2019
Amersfoort : Stowa (Stowa rapport 2019-26) - ISBN 9789057738616 - 117
Timing it right: Non-consumptive effects on prey recruitment magnify overtime
Bertolini, C. ; Capelle, J.J. ; Timmermans, K. ; Bouma, T.J. ; De Koppel, J. Van; Derksen, G.C.H. - \ 2019
Journal of Experimental Marine Biology and Ecology 513 (2019). - ISSN 0022-0981 - p. 47 - 54.
Predator-prey - Indirect interactions - Population dynamics - Benthic ecology - Mytilus edulis - Asterias rubens
Many organisms rely on chemical signals and cues to determine habitat suitability and safety. Chemical signals can mediate many interactions, including those between predators and their prey. Altering prey behaviour, these non-consumptive effects (NCEs) can influence population and community dynamics. Understanding how NCEs influence early life history stages, such as ‘decisions’ of benthic species with planktonic larvae about where to settle, can provide useful information on the ecological functioning of these systems as well as the management for commercial usage, although most studies have so far focused on intertidal systems which are already subject to a set of stressful conditions. With a shallow subtidal field experiment we investigated NCEs of the common starfish Asterias rubens on one of its main preys, the blue mussels Mytilus edulis. We tested the hypotheses that (1) the presence of starfish reduces mussels settlement and that (2) the mussels that settle will invest more energy towards induced defences than to growth, and will thus remain smaller than mussels settling in an area without starfish. Two independent trials revealed a significant reduction of mussel spat on the collectors in the presence of starfish after a two-week deployment period. There was however no effect of starfish on the size distribution of the mussel spat. The delayed observation of effects of starfish, absent after the first week but evident afterwards, suggests a time dependency of NCE's on spat settlement. Harnessing this ecologically important information has the potential to increase yield of mussel seeds available for fisheries by either removing starfish from the ground-based settling areas at the onset and for the duration of spatfall or by using floating substrates that are away from the bottom-bound starfish. Moreover, these results also underlines the potential of using predator cues in the application for sustainable natural antifouling compounds in situations with low recruitment pressures.
Comparison of madder (Rubia tinctorum L.) and weld (Reseda luteola L.) total extracts and their individual dye compounds with regard to their dyeing behaviour, colour, and stability towards light
Willemen, Hendra ; Meijdenberg, Geeske J.P. van den; Beek, Teris A. van; Derksen, Goverdina C.H. - \ 2019
Coloration Technology 135 (2019)1. - ISSN 1472-3581 - p. 40 - 47.

This paper reports on the colorimetric properties of natural dyes from madder and weld plants. For both crops, a comparison is made among several individual dye compounds and the total plant extracts. Dyeing properties, colour properties and colour stability have been studied. Insight has been gained into the role of the major dye compounds present in the plant. For madder as well as for weld, the use of the total plant extract is considered to be advantageous over the use of individual dye compounds in terms of solubility, colour tone and stability towards light, and non-coloured components present in the plant extract are considered to be responsible for increasing the solubility and the stability of the dye compounds.

Photo-stability of a flavonoid dye in presence of aluminium ions
Villela, Alexandre ; Vuuren, Monique S.A. van; Willemen, Hendra M. ; Derksen, Goverdina C.H. ; Beek, Teris A. van - \ 2019
Dyes and Pigments 162 (2019). - ISSN 0143-7208 - p. 222 - 231.
Flavonoid - Light-fastness - Luteolin - Natural dye - Reseda luteola - Weld

The main colouring compounds of the dye plant weld (Reseda luteola L.) are the flavones luteolin (lut), lut-7-O-glucoside and lut-7,3ʹ-O-diglucoside. Alum (an aluminium salt)-premordanted wool dyed with weld leads to yellow colours that are of low resistance to light. The photo-stability of lut in aerated methanol–water 8:2 (v/v) solution upon irradiation with light above 300 nm was studied at different lut–Al3+ ratios. Experiments using extracts of weld to dye wool premordanted with increasing quantities of aluminium salts were also carried out. The photo-stability of lut in the polar protic solvent and the photo-resistance (light-fastness) of the colour of weld-dyed wool decrease with increasing concentrations of aluminium ions. Thus, the lower the [Al3+] used for mordanting the wool, the more light-fast its colour. Lowering the [Al3+] appears to have no negative influence on the wash-fastness of the colour. As the gain in light-fastness by the use of low [Al3+] to premordant the wool is not extensive, however, this does not seem to be a way to meet today's requirement of light-fastness of the colours of dyed textiles by itself. Nevertheless, it may be part of a bigger strategy to address the need for increased light-fastness of the colour of wool dyed with weld. Implementation of this approach by dyers is expected to clarify whether it results in benefits for textile dyeing practice.

Foundation species enhance food web complexity through non-trophic facilitation
Borst, Annieke C.W. ; Verberk, Wilco C.E.P. ; Angelini, Christine ; Schotanus, Jildou ; Wolters, Jan Willem ; Christianen, Marjolijn J.A. ; Zee, Els M. van der; Derksen-Hooijberg, Marlous ; Heide, Tjisse van der - \ 2018
PLoS ONE 13 (2018)8. - ISSN 1932-6203

Food webs are an integral part of every ecosystem on the planet, yet understanding the mechanisms shaping these complex networks remains a major challenge. Recently, several studies suggested that non-trophic species interactions such as habitat modification and mutualisms can be important determinants of food web structure. However, it remains unclear whether these findings generalize across ecosystems, and whether non-trophic interactions affect food webs randomly, or affect specific trophic levels or functional groups. Here, we combine analyses of 58 food webs from seven terrestrial, freshwater and coastal systems to test (1) the general hypothesis that non-trophic facilitation by habitat-forming foundation species enhances food web complexity, and (2) whether these enhancements have either random or targeted effects on particular trophic levels, functional groups, and linkages throughout the food web. Our empirical results demonstrate that foundation species consistently enhance food web complexity in all seven ecosystems. Further analyses reveal that 15 out of 19 food web properties can be well-approximated by assuming that foundation species randomly facilitate species throughout the trophic network. However, basal species are less strongly, and carnivores are more strongly facilitated in foundation species’ food webs than predicted based on random facilitation, resulting in a higher mean trophic level and a longer average chain length. Overall, we conclude that foundation species strongly enhance food web complexity through non-trophic facilitation of species across the entire trophic network. We therefore suggest that the structure and stability of food webs often depends critically on non-trophic facilitation by foundation species.

Diergeneesmiddelen & hormonen in het milieu door de toediening van drijfmest : Een verkennende studie in de Provincie Gelderland naar antibiotica, antiparasitaire middelen, coccidiostatica en natuurlijke hormonen in mest, (water)bodem, grondwater en oppervlaktewater
Lahr, Joost ; Derksen, Anja ; Wipfler, Louise ; Schans, Milou van de; Berendsen, Bjorn ; Blokland, Marco ; Dimmers, Wim ; Bolhuis, Popko ; Smidt, Rob - \ 2018
Wageningen : Wageningen Environmental Research (Wageningen Environmental Research rapport 2898) - 89
Het voorkomen, de risico’s en de mogelijkheden voor emissiereductie van humane geneesmiddelen in water krijgen de afgelopen jaren steeds meer aandacht. Naar diergeneesmiddelen gaat tot op heden minder aandacht uit dan naar humane geneesmiddelen. In 2017 is daarom onderzoek verricht naar de lotgevallen van diergeneesmiddelen in drijfmest uit de intensieve veehouderij die toegediend wordt op het land. Het onderzoek richtte zich op de kalver- en varkenshouderij en met name op het risico van uitspoeling. Voor het onderzoek werden vijf op zandgrond gelegen bedrijven in Gelderland geselecteerd uit iedere sector. Voorafgaand aan de mesttoediening werd een monster van de mest zelf genomen en op diverse tijdstippen voor en na de mestinjectie werden de bodem, het grondwater en het oppervlaktewater en sediment van kavelsloten naast de bemeste percelen bemonsterd. In al deze monsters werden de concentraties van een groot aantal antibiotica, antiparasitaire middelen, coccidiostatica en natuurlijke hormonen bepaald middels chemische analyse.
Multifunctionaliteit is the winning factor
Stremke, Sven - \ 2017
Interactive effects of oxygen, carbon dioxide and flow on photosynthesis and respiration in the scleractinian coral Galaxea fascicularis
Osinga, Ronald ; Derksen-Hooijberg, Marlous ; Wijgerde, Tim ; Verreth, Johan A.J. - \ 2017
Journal of Experimental Biology 220 (2017)12. - ISSN 0022-0949 - p. 2236 - 2242.
Carbon dioxide - Coral - Flow - Oxygen - Photosynthesis - Respiration

Rates of dark respiration and net photosynthesis were measured for six replicate clonal fragments of the stony coral Galaxea fascicularis (Linnaeus 1767), which were incubated under 12 different combinations of dissolved oxygen (20%, 100% and 150% saturation), dissolved carbon dioxide (9.5 and 19.1 μmol l-1) and water flow (1-1.6 versus 4-13 cm s-1) in a repeated measures design. Dark respiration was enhanced by increased flow and increased oxygen saturation in an interactive way, which relates to improved oxygen influx into the coral tissue. Oxygen saturation did not influence net photosynthesis: neither hypoxia nor hyperoxia affected net photosynthesis, irrespective of flow and pH, which suggests that hyperoxia does not induce high rates of photorespiration in this coral. Flow and pH had a synergistic effect on net photosynthesis: at high flow, a decrease in pH stimulated net photosynthesis by 14%. These results indicate that for this individual of G. fascicularis, increased uptake of carbon dioxide rather than increased efflux of oxygen explains the beneficial effect of water flow on photosynthesis. Rates of net photosynthesis measured in this study are among the highest ever recorded for scleractinian corals and confirm a strong scope for growth.

'Transport afstemmen op het product'
Hogeveen-van Echtelt, Esther - \ 2016
Voedingspatroon inventariseren
Derksen, M. ; Wagemakers, A. - \ 2016
Tijdschrift voor verloskundigen (2016)6. - ISSN 0378-1925 - 8 p.
Een voedingsinventarisatie kan bijdragen aan een gerichte voedingsbegeleiding op maat aan zwangere vrouwen. Marloes Derksen zocht in de literatuur naar een goede methode en naar de succesfactoren en barrières voor verloskundigen voor het geven van voedingsbegeleiding.
Screening of hot spots of emerging pollutants in soil, ground water and surface water in The Netherlands: breaking the vicious cycle.
Lahr, J. ; Laak, T. ter; Derksen, A. - \ 2015
Screening of hot spots of emerging pollutants in soil, ground water and surface water in the netherlands: breaking the vicious cycle
Lahr, J. ; Laak, T.L. ter; Derksen, A. - \ 2014
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.
Analysis of a Natural Yellow Dye: An Experiment for Analytical Organic Chemistry
Villela, A. ; Derksen, G.C.H. ; Beek, T.A. van - \ 2014
Journal of Chemical Education 91 (2014)4. - ISSN 0021-9584 - p. 566 - 569.
weld
This experiment exposes second-year undergraduate students taking a course in analytical organic chemistry to high-performance liquid chromatography (HPLC) and quantitative analysis using the internal standard method. This is accomplished using the real-world application of natural dyes for textiles. The extracted flavonoids of the plant weld are responsible for the yellow color of the dyed wool. Dried and ground weld is extracted for dyeing wool and quantifying the plant’s three main flavonoids. The students also mimic the work of chemists investigating historical textiles by carrying out a small-scale extraction of the dyed wool. Twenty-one students carried out the experiment, and their samples were analyzed using either a traditional 5 µm-particle size HPLC column or a modern 1.8 µm-particle size ultrahigh-pressure liquid chromatography (UHPLC) column mounted in a conventional HPLC system.
Screening van hot spots van nieuwe verontreinigingen in de bodem, het grondwater en het oppervlaktewater: het doorbreken van de vicieuze cirkel
Lahr, J. ; Laak, T.L. ter; Derksen, A. ; Gylstra, R. ; Harthoorn, J. - \ 2013
Spectrophotometric comparison of the content of chlorophylls in weld (Reseda luteola)
Villela, A. ; Derksen, G.C.H. ; Zuilhof, H. ; Beek, T.A. van - \ 2011
Analytical Methods 3 (2011)6. - ISSN 1759-9660 - p. 1424 - 1427.
plant - dyes
An analytical method for the comparison of the content of chlorophylls and their structurally similar breakdown products in weld is described
Fast chromatographic separation for the quantitation of the main flavone dyes in Reseda luteola (weld)
Villela, A. ; Klift, E.J.C. van der; Mattheussens, E.S.G.M. ; Derksen, G.C.H. ; Zuilhof, H. ; Beek, T.A. van - \ 2011
Journal of Chromatography. A, Including electrophoresis and other separation methods 1218 (2011)47. - ISSN 0021-9673 - p. 8544 - 8550.
performance liquid-chromatography - diode-array detection - l. - identification - quantification - bilobalide - portugal
In the past decades, there has been a renewed interest in the use of natural dye plants for textile dyeing, e.g. Reseda luteola (weld). Its main yellow dye constituents are the flavones luteolin-7,3'-O-diglucoside, luteolin-7-O-glucoside and luteolin. The aim of this work was to develop a simple validated industrially usable quantitative method to assess the flavone content of R. luteola samples. The flavones were overnight extracted from the dried and ground aerial parts of the plant at room temperature via maceration with methanol-water 8:2. Afterwards, they were quantified through internal standardisation against chrysin by RP-HPLC-UV at 345nm. The efficiency of the one-step extraction was 95%. The limits of detection (LOD) and quantitation (LOQ) were =1ng and =3ng, respectively, providing ample sensitivity for the purpose. The precision expressed as relative standard deviation of the entire method was
Biomassa voor energie in de stadsregio Arnhem-Nijmegen : ontwikkelingen van een strategie voor biomassa uit bos, natuur en landschap
Spijker, J.H. ; Vries, E.A. de; Derksen, J.T.P. - \ 2010
Wageningen : Alterra (Alterra-rapport 2095) - 30
biomassa productie - bio-energie - landgebruik - haalbaarheidsstudies - stedelijke gebieden - landschapsbeheer - betuwe - biobased economy - biomass production - bioenergy - land use - feasibility studies - urban areas - landscape management - betuwe - biobased economy
De Stadsregio Arnhem-Nijmegen heeft behoefte aan een strategie voor de optimale inzet van biomassa uit natuur en landschap voor energie-opwekking. In dit rapport wordt inleidend het huidige aandeel duurzame energie in Nederland en de beleidsopgave uiteengezet. Daarna wordt aangegeven dat er legio kansen zijn voor oogst van biomassa uit het landschap, waarbij wel gewezen wordt op het belang van cascadering. Cascadering houdt in dat biomassa zo hoogwaardig mogelijk wordt weggezet, en dus pas in laatste instantie voor energie-opwekking. Grote kansen doen zich voor bij reststromen die nu nog als afval kunnen worden beschouwd. De houtige reststromen kunnen direct worden ingezet voor warmte-opwekking, de grazige reststromen voor vergisting. Het rapport sluit af met een aantal aanbevelingen voor de Stadsregio..
10 Jaar Triade: een evaluatie...
Wagelmans, M. ; Derksen, A. ; Lud, D. ; Mesman, M. ; Faber, J.H. - \ 2010
Bodem 20 (2010)2. - ISSN 0925-1650 - p. 18 - 20.
bodemverontreiniging - methodologie - toxicologie - onderzoek - kwaliteitsnormen - bodemecologie - ecologische risicoschatting - soil pollution - methodology - toxicology - research - quality standards - soil ecology - ecological risk assessment
Sinds 1998 wordt de Triade gebruikt voor het schatten van locatiespecifieke ecologische risico's van bodemverontreiniging. In 2008 en 2009 is een proces-NEN ontwikkels voor ecologische risicobeoordeling. Ter ondersteuning hiervan is een evaluatie uitgevoerd van all in Nederland uitgevoerde Triade projecten.
10 years of terrestrial ecological risk assessment: An evaluation
Wagelmans, M. ; Derksen, A. ; Mesman, M. ; Lud, D. ; Faber, J.H. - \ 2009
Ecologische effecten van metaalverontreiniging in het overstromingsgebied van de Dommel. Triade onderzoek, ecologische risico's en mogelijkheden voor inrichting en beheer
Derksen, J.G.M. ; Lahr, J. ; Kort, T. de; Tuin, T. ; Postma, J.F. ; Klok, T.C. ; Brink, N.W. van den; Lange, H.J. de; Kools, S.A.E. ; Hout, A. van der; Harmsen, J. ; Faber, J.H. - \ 2008
Amsterdam : Grontmij/AquaSense, Alterra & Grontmij - 81
overstromingsgebieden - bodemverontreiniging - cadmium - zink - rivieren - lichte-matig zware kleigronden - toxicologie - ecologie - nederland - natuurbeheer - kempen - noord-brabant - bottomlands - soil pollution - cadmium - zinc - rivers - clay loam soils - toxicology - ecology - netherlands - nature management - kempen - noord-brabant
De rivier de Dommel is sterk verontreinigd met cadmium en zink als gevolg van historische activiteiten van de zinkindustrie. Bij overstroming worden deze metalen, gebonden aan organisch stof en kleideeltjes, afgezet op de bodem in het overstromingsgebied. Als gevolg hiervan is ook het overstromingsgebied van de Dommel plaatselijk sterk verontreinigd. De overheid heeft voor een belangrijk deel van het Dommeldal natuurdoelstellingen opgesteld, waaronder het realiseren van de Ecologische Hoofd Structuur. Onduidelijkheid over de invloed van de metaalverontreiniging op de ecologie en natuurontwikkeling heeft geleid tot stagnatie van grondaankopen om deze EHS te kunnen realiseren. Om deze stagnatie op te heffen heeft het projectbureau Actief Bodembeheer de Kempen nader onderzoek laten uitvoeren. Het onderzoek heeft zich gericht op de vraag wat de locatiespecifieke ecologische risico’s zijn van de cadmium- en zinkverontreinigingen bij verschillende natuur(doel)typen die in het Dommeldal aanwezig zijn of ontwikkeld gaan worden. Het betreft hier de natuur(doel)typen die zich in een gebied bevinden dat gemiddeld één of meerdere keren per tien jaar overstroomd wordt. Deze natuur(doel)typen zijn voornamelijk bloemrijk grasland, nat schraalgrasland, moeras en elzenbroekbos. Het onderzoek is stapsgewijs uitgevoerd en wordt TRIADE genoemd vanwege de drie componenten waaruit het is opgebouwd te weten chemie, toxicologie en veldmetingen
De ecopyramide : biomassa beter benutten
Derksen, J.T.P. ; Seventer, E. van; Braber, K.J. ; Liere, K.J. van; Kasteren, J.H. van; Wilt, J.G. de - \ 2008
Utrecht : InnovatieNetwerk Groene Ruimte en Agrocluster (Rapport / InnovatieNetwerk 08.2.193) - ISBN 9789050593687 - 64
duurzaamheid (durability) - energiebronnen - energie - duurzame energie - durability - energy sources - energy - sustainable energy
De Nederlandse overheid probeert duurzame ontwikkeling te vergroten. De ecopyramide is daarbij een middel. De ecopyramide is een concept waarin het gebruik van biomassa wordt geoptimaliseerd. De ecopyramide brengt in beeld welke aspecten moeten worden afgewogen bij de inzet van biomassa en in welke volgorde de producten moeten worden benut. Leidraad daarbij is het maximaal gebruik van de ordening van moleculen. Daarbij staat het gebruik van biomassa voor medicijnen en voedsel voorop, gevolgd door materialen, chemische grondstoffen, transportbrandstoffen en arbeid (elektriciteit) en tot slot warmte. Het achterliggende motief is de plicht om natuurproducten, gestolde zonne-energie, zo efficiënt mogelijk te gebruiken
Detection of conformational changes in immunoglobulin G using isothermal titration calorimetry with low molecular weight probes
Rispens, T. ; Lakemond, C.M.M. ; Derksen, N.I.L. ; Aalberse, R.C. - \ 2008
Analytical Biochemistry 380 (2008)2. - ISSN 0003-2697 - p. 303 - 309.
1-anilino-8-naphthalene sulfonate - binding-sites - fluorescence - proteins - igg - ans - stability
Proteins for therapeutic use may contain small amounts of partially misfolded monomeric precursors to postproduction aggregation. To detect these misfolded proteins in the presence of an excess of properly folded protein, fluorescent probes such as 8-anilino-1-naphthalene sulfonate (ANS) are commonly used. We investigated the possibility of using isothermal titration calorimetry (ITC) to improve the detection of this type of conformational change using hydrophobic probes. As a case study, conformational changes in human polyclonal immunoglobulin G (IgG) were monitored by measuring the enthalpies of binding of ANS using ITC. Results were compared with those using fluorescence spectroscopy. IgG heated at 63 degrees C was used as a model system for "damaged" IgG. Heat-treated IgG can be detected already at levels below 5% with both ITC and fluorescence. However, ITC allows a much wider molar probe-to-protein ratio to be sampled. In particular, using reverse titration experiments (allowing high probe-to-protein ratios not available to fluorescence spectroscopy), an increase in the number of binding sites with a K(d)>10 mM was observed for heat-treated IgG, reflecting subtle changes in structure. Both ITC and fluorescence spectroscopy showed low background signals for native IgG. The nature of the background signals was not clear from the fluorescence measurements. However, further analysis of the ITC background signals shows that a fraction (8%) binds ANS with a dissociation constant of approximately 0.2 mM. Measurements were also carried out at pH 4.5. Precipitation of IgG was induced by ANS at concentrations above 0.5 mM, interfering with the ITC measurements. Instead, with the nonfluorescent probes 4-amino-1-naphthalene sulfonate and 1-naphthalene sulfonate, no precipitation is observed. These probes yield differences in the enthalpies of binding to heated and nonheated IgG similar to ANS. The data illustrate that ITC with low-molecular-weight probes is a versatile tool to monitor conformational changes in proteins with a wider application potential than fluorescence measurements.
Biobrood van eigen bodem: een ketenproject
Postma, R. ; Bakker, A. den; Derksen, V. ; Kruiger, K. ; Maassen, J. ; Osman, A.M. ; Schepers, H.E. - \ 2008
Wageningen [etc.] : Nutriënten Management Instituut (Rapport / NMI 1136) - 30
biologische voedingsmiddelen - graanproducten - brood - landbouwplantenteelt - akkerbouw - ketenmanagement - regionale voedselketens - organic foods - cereal products - bread - crop husbandry - arable farming - supply chain management - regional food chains
In 2007 is het ketenproject “Biobrood van eigen bodem” uitgevoerd in het kader van het coinnovatieprogramma biologische afzetketens. Het betrof een samenwerkingsproject van een aantal ketenpartijen uit de biologische broodketen en een aantal kennisinstellingen. Het doel van het project was gericht op het verbeteren van het imago van biologisch brood door het verhogen van het aandeel Nederlandse tarwe, wat mogelijk een bijdrage kan leveren aan het vergroten van de afzetmogelijkheden ervan. Daartoe is een consumentenonderzoek uitgevoerd en zijn veldproeven met bemestingsvarianten uitgevoerd. Tenslotte zijn met de tarwe uit de veldproeven bakproeven uitgevoerd.
Het Buys Ballot symposium 2006
Beersma, J.J. ; Berg, W.J. van de; Derksen, J. ; Kuipers Munneke, P. ; Mathies, J. ; Overeem, A. ; Pieterse, G. ; Schroter, J.S. ; Vigano, I. ; Vis-Star, N. ; Steeneveld, G.J. - \ 2007
Meteorologica / Nederlandse Vereniging van Beroeps Meteorologen 16 (2007)1. - ISSN 0929-1504 - p. 13 - 17.
Modulation of cell wall structure and composition using a fungal cellulose-binding domain
Quentin, M.G.E. ; Indemans, M.H.G. ; Derksen, J. ; Jong, E. de; Valk, H.C.P.M. van der - \ 2004
In: Wood fibre cell walls : methods to study their formation, structure and properties / Schmitt, U., Ander, P., Barnett, J.R., Emons, A.M.C., Jeronimidis, G., Saranpää, P., Tschegg, S., Uppsala : Swedish University of Agricultural Sciences - ISBN 9157668035 - p. 45 - 56.
Two Validated HPLC Methods for the Quantification of Alizarin and other Anthraquinones in Rubia tinctorum Cultivars
Derksen, G.C.H. ; Lelyveld, G.P. ; Beek, T.A. van; Capelle, A. ; Groot, Æ. de - \ 2004
Phytochemical Analysis 15 (2004)6. - ISSN 0958-0344 - p. 397 - 406.
cell-suspension cultures - performance liquid-chromatography - madder root - morinda-citrifolia - quantitative-analysis - tissue-cultures - lucidin - hydroxyanthraquinones - growth - identification
Direct and indirect HPLC-UV methods for the quantitative determination of anthraquinones in dried madder root have been developed, validated and compared. In the direct method, madder root was extracted twice with refluxing ethanol-water. This method allowed the determination of the two major native anthraquinone glycosides lucidin primeveroside and ruberythric acid. In the indirect extraction method, the anthraquinone glycosides were first converted into aglycones by endogenous enzymes and the aglycones were subsequently extracted with tetrahydroturan-water and then analysed. In this case the anthraquinones alizarin, purpurin and nordamnacanthal may be determined. The content of nordamnacanthal is proportional to the amount of lucidin primeveroside 14 originally present. The indirect extraction method is easier to apply. Different madder cultivars were screened for their anthraquinone content. Copyright (C) 2004 John Wiley Sons, Ltd.
Verwijdering van hormoonverstorende stoffen in rwzi's
Loeffen, P. ; Lahr, J. ; Derksen, A. ; Uijterlinde, C. ; Roeleveld, P. - \ 2004
H2O : tijdschrift voor watervoorziening en afvalwaterbehandeling 37 (2004)5. - ISSN 0166-8439 - p. 19 - 21.
afvalwaterbehandeling - rioolafvalwater - hormonen - oestrogenen - waterzuivering - oppervlaktewater - waterverontreiniging - zuiveringsinstallaties - hormoonverstoorders - waste water treatment - sewage effluent - hormones - oestrogens - water treatment - surface water - water pollution - purification plants - endocrine disruptors
Door de STOWA is eind vorig jaar een literatuurstudie naar de verwijdering van hormoonverstorende stoffen (ook wel endocrine disrupting chemicals of EDC's genoemd) in rioolwaterzuiveringsinstallaties verricht. Hieruit blijkt dat, ondanks een redelijke verwijdering in de rwzi, de concentraties van bepaalde EDC's in het effluent nog steeds kunnen leiden tot biologische effecten. De grootste risico's geven de oestrogene hormonen 17a-ethinyloestradiol ('de pil'), 17beta-oestradiol en oestron en de industriële detergenten nonylfenol en nonylfenolethoxylaten. Het is onduidelijk hoe de huidige rioolwaterzuiveringsinstallaties geoptimaliseerd kunnen worden om hormoonverstorende stoffen te verwijderen. Geavanceerde technieken lijken de beste resultaten op te leveren
Cloning, characterisation and assessment of the cell wall modifying ability of a fungal cellulose-binding domain
Quentin, M.G.E. - \ 2003
Radboud University Nijmegen. Promotor(en): C. Mariani, co-promotor(en): Johan Derksen; H.C.P.M. van der Valk. - Nijmegen : Katholieke Universiteit Nijmegen - ISBN 9064642583 - 149
plantenvezels - celwanden - enzymactiviteit - bindende eiwitten - chemische samenstelling - genexpressie - arabidopsis thaliana - schimmels - cellulose - genetische modificatie - bacteriën - dierkloneren - fungi - bacteria - plant fibres - cell walls - enzyme activity - binding proteins - chemical composition - gene expression - genetic engineering - animal cloning
Chemical and enzymatic hydrolysis fo anthraquinone glycosides from madder roots
Derksen, G.C.H. ; Naayer, M. ; Beek, T.A. van; Capelle, A. ; Haaksman, I.K. ; Doren, H.A. ; Groot, Æ. de - \ 2003
Phytochemical Analysis 14 (2003)3. - ISSN 0958-0344 - p. 137 - 144.
rubia-tinctorum l - alcoholic aroma formation - tea leaves - hydroxyanthraquinones - primeverosidase - mutagenicity - genotoxicity - derivatives - extracts - lucidin
For the production of a commercially useful dye extract from madder, the glycoside ruberythric acid has to be hydrolysed to the aglycone alizarin which is the main dye component. An intrinsic problem is the simultaneous hydrolysis of the glycoside lucidin primeveroside to the unwanted mutagenic aglycone lucidin. Madder root was treated with strong acid, strong base or enzymes to convert ruberythric acid into alizarin and the anthraquinone compositions of the suspensions were analysed by HPLC. A cheap and easy method to hydrolyse ruberythric acid in madder root to alizarin without the formation of lucidin turned out to be the stirring of dried madder roots in water at room temperature for 90 min: this gave a suspension containing pseudopurpurin, munjistin, alizarin and nordamnacanthal. Native enzymes are responsible for the hydrolysis, after which lucidin is converted to nordamnacanthal by an endogenous oxidase
Analysis of anthraquinones in Rubia tinctorum L. by liquid chromatography coupled with diode-array UV and mass spectrometric detection
Derksen, G.C.H. ; Niederländer, H.A.G. ; Beek, T.A. van - \ 2002
Journal of Chromatography. A, Including electrophoresis and other separation methods 978 (2002). - ISSN 0021-9673 - p. 119 - 127.
A liquid chromatographic (LC) method for the separation of both anthraquinone glycosides and aglycones in extracts of Rubia tinctorum was improved. For on-line MS detection atmospheric pressure chemical ionisation as well as electrospray ionisation (ESI) were used. The glycosides were ionised in both positive and negative ionisation (NI) mode, the aglycones only in the NI mode. With ESI ammonia was added to the eluent post-column to deprotonate the compounds. The efficiency of mass detection of the hydroxyanthraquinone aglycones was found to depend on the pKa value of the component. LC–diode-array detection and LC–MS provide useful complementary information for the identification of anthraquinones in plant extracts, which was proven with the identification of munjistin and pseudopurpurin.
Description of a cellulose-binding domain and a linker sequence from Aspergillus fungi
Quentin, M. ; Ebbelaar, M. ; Derksen, J. ; Mariani, C. ; Valk, H. van der - \ 2002
Applied Microbiology and Biotechnology 58 (2002)5. - ISSN 0175-7598 - p. 658 - 662.
Rubia Tinctorum L.
Derksen, G.C.H. ; Beek, T.A. van - \ 2002
In: Studies in natural products chemistry / Atta-ur-Rahman Amsterdam : Elsevier - ISBN 9780444510044 - p. 629 - 684.
Method for the production of a dye preparation based on madder root
Derksen, G.C.H. ; Beek, T.A. van; Capelle, A. - \ 2001
Octrooinummer: EP1191070, verleend: 2001-09-26.
The present invention relates to a method for the production of a dye preparation from madder root, comprising extraction of madder root in water at a temperature below 70-75 DEG C, preferably below 65 DEG C, while providing oxygen to the reaction mixture of madder root in water to obtain the dye preparation and to the dye preparation thus obtained
Red, redder, madder : analysis and isolation of anthraquinones from madder roots (Rubia tinctorum)
Derksen, G.C.H. - \ 2001
Wageningen University. Promotor(en): Æ. de Groot; A. Capelle; T.A. van Beek. - S.l. : S.n. - ISBN 9789058084620 - 150
antrachinonen - rubia tinctorum - analyse - plantextracten - anthraquinones - rubia tinctorum - analysis - plant extracts

The roots of Rubia tinctorum L. (madder) are the source of a natural dye. The dye components are anthraquinones with alizarin being the main dye component. Alizarin as such is present in madder root in only small quantities, most of the alizarin is present as its glycoside ruberythric acid. The sugar in this disaccharide is primeverose. Madder roots have been used to dye textiles in many parts of the world since ancient times. From 1600-1900 there was a heavy trade in madder throughout Europe. Madder root was an important export product for Holland. In 1868 Graebe and Liebermann discovered how to prepare alizarin synthetically. At the end of the 19 thcentury the madder culture rapidly declined due to the cheaper production of synthetic alizarin. Production of synthetic alizarin gives polluting side products. Nowadays the use and production of natural dyes becomes more popular due to the growing awareness for the environment and the need for alternative crops. An important element in the revitalisation of madder as an industrial crop is that the dye preparation from madder should be able to compete in quality and price with synthetic alizarin.Due to this renewed interest this research was initiated with this thesis as result.

For the simultaneous identification of the anthraquinone glycosides and aglycones in extracts of madder root a high-pressure liquid chromatography method (HPLC) was developed. The anthraquinones were separated on an end-capped C 18 -RP column with a water-acetonitrile gradient as eluent and measured with ultra violet (UV) detection at 250 nm. For the identification of anthraquinones on-line a mass spectrometer (MS) and a diode-array detector were used.

The main anthraquinones in an ethanol-water extract of madder root are the glycosides lucidin primeveroside and ruberythric acid and the anthraquinones pseudopurpurin and munjistin, which contain a carboxylic acid moiety. Beside these compounds also small amounts of the aglycones alizarin and purpurin could be detected and sometimes also lucidin was present.

For the production of a commercially useful dye preparation from madder, the glycoside ruberythric acid should be hydrolysed to the aglycone alizarin, which is the main dye component. An intrinsic problem of the hydrolysis of ruberythric acid in madder root is the simultaneous conversion of lucidin primeveroside to the unwanted mutagenic aglycone lucidin. Madder root was treated with strong acid, strong base or enzymes to convert ruberythric acid into alizarin. The anthraquinone composition of the suspensions was analysed with HPLC-UV, HPLC-DAD and HPLC-MS.

Stirring of dried madder root in water at room temperature for 90 min gave a suspension with pseudopurpurin, munjistin, alizarin and nordamnacanthal. Nordamnacanthal originates from lucidin primeveroside, which is hydrolysed to lucidin and subsequently oxidised to the corresponding aldehyde nordamnacanthal by an endogenous hydrolase and oxidase respectively. Nordamnacanthal is not mutagenic. During this conversion oxygen is obligatory and can be added by stirring the suspension. This stirring is an easy method for simultaneously hydrolysing ruberythric acid and to getting rid of the mutagenic lucidin.

Different madder root cultivars were screened for their anthraquinone composition and amount of the main anthraquinones. The concentration of alizarin varied from 6.1 to11.8 mg/g root. If madder root was cultivated for three instead of two years the amount of alizarin increased from 6.7 mg/g to 8.7 mg/g.

A number of different methods were compared for their capacity to isolate alizarin from the rest of the plant material. To make a first selection attention was mainly paid to the yield of alizarin. Three routes were selected as most promising for an industrial application. These three methods were tested at a larger scale. The first method consisted of the following steps: conversion of madder root (250 g) by endogenous enzymes, extraction of madder root with refluxing ethanol-water, hot filtration, evaporation to half of the original volume and precipitation at 4°C. An extract of 14.7 g was obtained which consisted for 35 % of anthraquinones. Of the total amount of alizarin available in the starting material 78% was extracted. The second method consisted of the following steps: extraction of madder root (250 g) with refluxing water, hot filtration, conversion of the glycosides in the filtrate by a madder root enzyme extract and precipitation at 4°C. An extract of 3.2 g was obtained of which 38 % were anthraquinones. Of the total amount of alizarin available in the starting material 19% was extracted. The third method consisted of the following steps: extraction of madder root with an aqueous surfactant solution, twice C 18 chromatography for extracting alizarin, elution of alizarin with methanol and evaporation. An extract of 17.1 g was obtained of which 11 % were anthraquinones. Of the total amount of alizarin available in the starting material 98% was extracted.

For the development of an economically feasible route these three methods have to be further optimised. After optimisation the three routes have to be compared in terms of amount of extract obtained, alizarin content, dyeing capacity, costs and industrial applicability of the procedure.

Succes- en faalfactoren van agrificatie in Nederland
Roekel, G.J. van; Koster, A.C. ; Stijnen, D.A.J.M. ; Derksen, H. ; Fossen, M. ; Maasen, R. - \ 2000
Wageningen : ATO (ATO Rapport 607) - ISBN 9085850088 - 56
industriële gewassen - industriële toepassingen - vervangbare hulpbronnen - duurzaamheid (sustainability) - landbouwbeleid - beoordeling - kwantitatieve analyse - kwalitatieve analyse - industrial crops - industrial applications - renewable resources - sustainability - agricultural policy - assessment - quantitative analysis - qualitative analysis
Oils and fats in the food industry
Veldsink, J.W. ; Muuse, B.G. ; Derksen, J.T.P. - \ 2000
In: Raw ingredient quality in processed foods : the influence of agricultural principles and practices / Springett, M.B.,
Heat curing polymeric powder coating compositions for coating metal and other substrates have a content of unsaturated long chain fatty acid or ester to improve adhesion and appearance after baking.
Cuperus, F.P. ; German, A.L. ; Es, J.J.G.S. van; Derksen, J.T.P. ; Hamersveld, E.M.S. van - \ 1999
Octrooinummer: NL1009254, verleend: 1999-11-26.
Incorporation of unsaturated fatty acids or esters of these into polymer based powder coatings to improve adhesion and appearance after stoving. Powder coating lacquers or binders for pigmented powder coatings which comprise one or more polymers (I) and 20-80 wt. % on total weight of binder of an unsaturated fatty acid (II) or an ester of this.
Pollen tubes of flavonol-deficient Petunia show striking alterations in wall structure leading to tube disruption
Derksen, J. ; Wezel, R. van; Knuiman, B. ; Ylstra, B. ; Tunen, A.J. van - \ 1999
Planta 207 (1999). - ISSN 0032-0935 - p. 575 - 581.
Changes in cell wall polysaccharides of green bean pods during development
Stolle-Smits, T. ; Beekhuizen, J.G. ; Kok, M.T.C. ; Pijnenburg, M. ; Recourt, K. ; Derksen, J.T.P. ; Voragen, A.G.J. - \ 1999
Plant Physiology 121 (1999)2. - ISSN 0032-0889 - p. 363 - 372.
A process for the preparation of a tertiary perester
Tammer, M.C. ; Meijer, J. ; Cuperus, F.P. ; Derksen, J.T.P. ; Kramer, G.F.H. - \ 1999
Octrooinummer: WO9905305, verleend: 1999-02-04.
The invention relates to a process for the preparation of a tertiary perester by contacting an acyl compound with a tertiary hydroperoxide in the presence of an enzyme catalyst. The acyl compound has the formula R1[C(O)OR2]n, wherein R1 is a linear or branched, saturated or unsaturated C1-C22 group, optionally containing one or more hetero atoms, R2 represents hydrogen or has the same meaning as described for R1, and n is 1-5, or a polyalcohol ester of R1C(O)OH, wherein R1 has the same meaning as described above. The tertiary hydroperoxide has the formula [HOOCR3R3]mR4, wherein R3 represents either a methyl or an ethyl group, R4 has the same meaning as described for R1, and m is 1-5.
New crops research in Europe
Derksen, J.T.P. - \ 1999
In: 90th AOCS Annual Meeting, May 10, 1999, at Orlando (USA)
Recent developments in the synthesis of fatty acid derivatives, AOCS monograph
Knothe, G. ; Derksen, J.T.P. - \ 1999
Champaign : AOCS Press
Seed oils rich in linolenic acid as renewable feedstock for environment-friendly crosslinkers in powder coatings
Overeem, A. ; Buisman, G.J.H. ; Derksen, J.T.P. ; Cuperus, F.P. ; Molhoek, L. ; Grisnich, W. ; Goemans, C. - \ 1999
Industrial Crops and Products 10 (1999)3. - ISSN 0926-6690 - p. 157 - 165.
In the work described, seed oils rich in linolenic acid were used for the synthesis of aliphatic oxiranes. The oils studied were linseed (Linum usitatissimum) oil, Canadian linseed oil and the oil of Lallemantia iberica. The oils contained 54.1, 60.2 and 68.0% of linolenic acid, respectively, and showed high theoretical iodine values of 211,226 and 236 g/hg. Unsaturations in the oils were used to introduce epoxides by epoxidation with in situ generated peroxyacetic acid. The epoxidized oils, showing high percentages of oxirane oxygen (9.4, 10.0 and 10.7%, were applied as crosslinkers in powder-coating formulations. The major advantage of these types of crosslinkers is that they are neither toxic nor mutagenic, in contrast with the widely applied synthetic triglycidyl isocyanurate (TGIC) crosslinkers. However, two potential problems exist when aliphatic oxiranes are compared with conventional TGIC systems. A decrease in glass transition temperature (T(g)) of the powder formulation and a higher degree of yellowing of the coating are often observed. In this paper the effects of using oils containing high linolenic acid contents on the yellowing of the coating and the T(g) of the powder, are studied. It appeared that aliphatic oxiranes are suitable as environment-friendly crosslinkers in powder-coating systems.
Influence of different isolation methods on the composition of anthraquinones in madder root extract (Rubia tinctorum L.)
Derksen, G.C.H. ; Beek, T.A. van; Capelle, A. ; Groot, C.P.G.M. de - \ 1999
In: 6th Symposium on Renewable Resources for the Chemical Industry together with the 4th European Symposium on Industrial Crops and Products: Bonn, 23-25 March, 1999. / Münster : LV Druck, Landwirtschaftsverlag GmbH, 1999. - (Schriftenreihe "Nachwachsende Rohstoffe"; 19). - ISBN: 3-7843-3019-3 - p. 535 - 538.
An electron microscopy study towards the texture of fresh, blanched and sterilised green bean pods (Phaseolus vulgaris L.)
Stolle-Smits, T. ; Donkers, J. ; Dijk, C. van; Derksen, J.W.M. ; Sassen, M.A. - \ 1998
Food Science and Technology = Lebensmittel-Wissenschaft und Technologie 31 (1998). - ISSN 0023-6438 - p. 237 - 244.
Enzymatic esterification of functionalized phenols for the synthesis of lipophilic antioxidants
Buisman, G.J.H. ; Helteren, C.T.W. van; Kramer, G.F.H. ; Veldsink, J.W. ; Derksen, J.T.P. ; Cuperus, F.P. - \ 1998
Biotechnology Letters 20 (1998)2. - ISSN 0141-5492 - p. 131 - 136.
Biodegradable binders and cross linkers from renewable resources: Euphorbia lagascae and Lallemantia iberica oils
Buisman, G.J.H. ; Overeem, A. ; Derksen, J.T.P. ; Cuperus, F.P. - \ 1998
Polymers Paint Colour Journal 188 (1998). - p. 14 - 16.
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