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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Agriculture versus wastewater pollution as drivers of macroinvertebrate community structure in streams
Burdon, F.J. ; Munz, N.A. ; Reyes, M. ; Focks, A. ; Joss, A. ; Räsänen, K. ; Altermatt, F. ; Eggen, R.I.L. ; Stamm, C. - \ 2019
Science of the Total Environment 659 (2019). - ISSN 0048-9697 - p. 1256 - 1265.
Aquatic ecosystems - Chemical pollution - Land use - Micropollutants - Multiple stressors - Pesticides

Water pollution is ubiquitous globally, yet how the effects of pollutants propagate through natural ecosystems remains poorly understood. This is because the interactive effects of multiple stressors are generally hard to predict. Agriculture and municipal wastewater treatment plants (WWTPs) are often major sources of contaminants for streams, but their relative importance and the role of different pollutants (e.g. nutrients or pesticides) are largely unknown. Using a ‘real world experiment’ with sampling locations up- and downstream of WWTPs, we studied how effluent discharges affected water quality and macroinvertebrate communities in 23 Swiss streams across a broad land-use gradient. Variation partitioning of community composition revealed that overall water quality explained approximately 30% of community variability, whereby nutrients and pesticides each independently explained 10% and 2%, respectively. Excluding oligochaetes (which were highly abundant downstream of the WWTPs) from the analyses, resulted in a relatively stronger influence (3%) of pesticides on the macroinvertebrate community composition, whereas nutrients had no influence. Generally, the macroinvertebrate community composition downstream of the WWTPs strongly reflected the upstream conditions, likely due to a combination of efficient treatment processes, environmental filtering and organismal dispersal. Wastewater impacts were most prominently by the Saprobic index, whereas the SPEAR index (a trait-based macroinvertebrate metrics reflecting sensitivity to pesticides) revealed a strong impact of arable cropping but only a weak impact of wastewater. Overall, our results indicate that agriculture can have a stronger impact on headwater stream macroinvertebrate communities than discharges from WWTP. Yet, effects of wastewater-born micropollutants were clearly quantifiable among all other influence factors. Improving our ability to further quantify the impacts of micropollutants requires highly-resolved water quality and taxonomic data with adequate spatial and temporal sampling. These improvements would help to better account for the underlying causal pathways that drive observed biological responses, such as episodic contaminant peaks and dispersal-related processes.

Supplement use and dietary sources of folate, vitamin D, and n-3 fatty acids during preconception : The GLIMP2 study
Looman, Moniek ; Berg, Claudia van den; Geelen, Anouk ; Samlal, Rahul A.K. ; Heijligenberg, Rik ; Klein Gunnewiek, Jacqueline M.T. ; Balvers, Michiel G.J. ; Leendertz-Eggen, Caroline L. ; Wijnberger, Lia D.E. ; Feskens, Edith J.M. ; Brouwer-Brolsma, Elske M. - \ 2018
Nutrients 10 (2018)8. - ISSN 2072-6643
Diet - Folate - N-3 fatty acids - Preconception - Supplements - Vitamin D

An adequate nutritional status during the preconception period is important, particularly for folate, vitamin D, and n-3 fatty acids (i.e., EPA+DHA). We aimed to determine supplement intake and the main dietary sources of folate, vitamin D, and EPA+DHA using the data of 66 Dutch women aged 18–40 years who wished to become pregnant. Additionally, associations of these intakes with their blood levels were examined. Dietary intake was assessed with a validated food frequency questionnaire, and supplement use with a structured questionnaire. 25-hydroxyvitamin D levels were determined in serum and folate and phospholipid EPA+DHA levels in plasma. Partial Spearman’s correlations, restricted cubic splines and trend analyses over tertiles of nutrient intakes were performed to examine intake-status associations. A large proportion of women did not meet the Dutch recommended intakes of folate (50%), vitamin D (67%), and EPA+DHA (52%). Vegetables were the main contributor to dietary folate intake (25%), oils and fats to dietary vitamin D intake (39%), and fish to dietary EPA+DHA intake (69%). Fourteen percent of the women had an inadequate folate status and 23% an inadequate vitamin D status. Supplemental folate intake, supplemental and dietary vitamin D intake and dietary EPA+DHA intake were significantly associated with their blood levels. In conclusion, even in our highly educated population, a large proportion did not achieve recommended folate, vitamin D and n-3 fatty acid intakes. Promotion of folate and vitamin D supplement use and fish consumption is needed to improve intakes and blood levels of these nutrients in women who wish to become pregnant.

Vermindering risico op herbicide-resistentie: meer eggen, schoffelen en wieden
Huiting, Hilfred - \ 2018
Early life exposure to PCB126 results in delayed mortality and growth impairment in the zebrafish larvae
Paolo, Carolina Di; Groh, Ksenia J. ; Zennegg, Markus ; Vermeirssen, Etiënne L.M. ; Murk, Albertinka J. ; Eggen, Rik I.L. ; Hollert, Henner ; Werner, Inge ; Schirmer, Kristin - \ 2015
Aquatic Toxicology 169 (2015). - ISSN 0166-445X - p. 168 - 178.
Delayed effects - Early life stages - Growth - PCB126 - Sublethal effects - Zebrafish

The occurrence of chronic or delayed toxicity resulting from the exposure to sublethal chemical concentrations is an increasing concern in environmental risk assessment. The Fish Embryo Toxicity (FET) test with zebrafish provides a reliable prediction of acute toxicity in adult fish, but it cannot yet be applied to predict the occurrence of chronic or delayed toxicity. Identification of sublethal FET endpoints that can assist in predicting the occurrence of chronic or delayed toxicity would be advantageous. The present study characterized the occurrence of delayed toxicity in zebrafish larvae following early exposure to PCB126, previously described to cause delayed effects in the common sole. The first aim was to investigate the occurrence and temporal profiles of delayed toxicity during zebrafish larval development and compare them to those previously described for sole to evaluate the suitability of zebrafish as a model fish species for delayed toxicity assessment. The second aim was to examine the correlation between the sublethal endpoints assessed during embryonal and early larval development and the delayed effects observed during later larval development. After exposure to PCB126 (3-3000. ng/L) until 5 days post fertilization (dpf), larvae were reared in clean water until 14 or 28 dpf. Mortality and sublethal morphological and behavioural endpoints were recorded daily, and growth was assessed at 28 dpf. Early life exposure to PCB126 caused delayed mortality (300. ng/L and 3000. ng/L) as well as growth impairment and delayed development (100. ng/L) during the clean water period. Effects on swim bladder inflation and cartilaginous tissues within 5 dpf were the most promising for predicting delayed mortality and sublethal effects, such as decreased standard length, delayed metamorphosis, reduced inflation of swim bladder and column malformations. The EC50 value for swim bladder inflation at 5 dpf (169. ng/L) was similar to the LC50 value at 8 dpf (188 and 202. ng/L in two experiments). Interestingly, the patterns of delayed mortality and delayed effects on growth and development were similar between sole and zebrafish. This indicates the comparability of critical developmental stages across divergent fish species such as a cold water marine flatfish and a tropical freshwater cyprinid. Additionally, sublethal effects in early embryo-larval stages were found promising for predicting delayed lethal and sublethal effects of PCB126. Therefore, the proposed method with zebrafish is expected to provide valuable information on delayed mortality and delayed sublethal effects of chemicals and environmental samples that may be extrapolated to other species.

Whole-genome sequencing of 234 bulls facilitates mapping of monogenic and complex traits in cattle
Daetwyler, H.D. ; Capitan, A. ; Pausch, H. ; Stothard, P. ; Binsbergen, R. van; Brondum, R.F. ; Liao, X. ; Djari, A. ; Rodriguez, S.C. ; Grohs, C. ; Esquerré, D. ; Bouchez, O. ; Rossignol, M.N. ; Klopp, C. ; Rocha, D. ; Fritz, S. ; Eggen, A. ; Bowman, P.J. ; Coote, D. ; Chamberlain, A.J. ; Anderson, C.L. ; Tassel, C.P. ; Hulsegge, B. ; Goddard, M.E. ; Guldbrandsten, B. ; Lund, M.S. ; Veerkamp, R.F. ; Boichard, D.A. ; Fries, R. ; Hayes, B.J. - \ 2014
Nature Genetics 46 (2014). - ISSN 1061-4036 - p. 858 - 865.
boophilus-microplus resistance - mitotic chromosomes - genotype imputation - holstein calves - dairy-cattle - milk-yield - bos-taurus - condensin - mutations - gene
The 1000 bull genomes project supports the goal of accelerating the rates of genetic gain in domestic cattle while at the same time considering animal health and welfare by providing the annotated sequence variants and genotypes of key ancestor bulls. In the first phase of the 1000 bull genomes project, we sequenced the whole genomes of 234 cattle to an average of 8.3-fold coverage. This sequencing includes data for 129 individuals from the global Holstein-Friesian population, 43 individuals from the Fleckvieh breed and 15 individuals from the Jersey breed. We identified a total of 28.3 million variants, with an average of 1.44 heterozygous sites per kilobase for each individual. We demonstrate the use of this database in identifying a recessive mutation underlying embryonic death and a dominant mutation underlying lethal chrondrodysplasia. We also performed genome-wide association studies for milk production and curly coat, using imputed sequence variants, and identified variants associated with these traits in cattle.
Design and Characterization of a 52K SNP Chip for Goats
Tosser-klopp, G. ; Bardou, P. ; Bouchez, O. ; Cabau, C. ; Crooijmans, R.P.M.A. ; Dong, Y. ; Donnadieu-Tonon, C. ; Eggen, A. ; Heuven, H.C.M. ; Jamli, S. ; Jiken, A.J. ; Klopp, C. ; Lawley, C.T. ; McEwen, J. ; Martin, P. ; Moreno, C.R. ; Mulsant, P. ; Nabihoudine, I. ; Pailhoux, E. ; Palhiere, I. ; Rupp, R. ; Sarry, J. ; Sayre, B.L. ; Tircazes, A. ; Wang, J. ; Wang, W. ; Zhang, W.G. - \ 2014
PLoS ONE 9 (2014)1. - ISSN 1932-6203
single-nucleotide polymorphisms - classical scrapie - genotyping assay - capra-hircus - prp gene - genome - association - polledness - generation - discovery
The success of Genome Wide Association Studies in the discovery of sequence variation linked to complex traits in humans has increased interest in high throughput SNP genotyping assays in livestock species. Primary goals are QTL detection and genomic selection. The purpose here was design of a 50–60,000 SNP chip for goats. The success of a moderate density SNP assay depends on reliable bioinformatic SNP detection procedures, the technological success rate of the SNP design, even spacing of SNPs on the genome and selection of Minor Allele Frequencies (MAF) suitable to use in diverse breeds. Through the federation of three SNP discovery projects consolidated as the International Goat Genome Consortium, we have identified approximately twelve million high quality SNP variants in the goat genome stored in a database together with their biological and technical characteristics. These SNPs were identified within and between six breeds (meat, milk and mixed): Alpine, Boer, Creole, Katjang, Saanen and Savanna, comprising a total of 97 animals. Whole genome and Reduced Representation Library sequences were aligned on >10 kb scaffolds of the de novo goat genome assembly. The 60,000 selected SNPs, evenly spaced on the goat genome, were submitted for oligo manufacturing (Illumina, Inc) and published in dbSNP along with flanking sequences and map position on goat assemblies (i.e. scaffolds and pseudo-chromosomes), sheep genome V2 and cattle UMD3.1 assembly. Ten breeds were then used to validate the SNP content and 52,295 loci could be successfully genotyped and used to generate a final cluster file. The combined strategy of using mainly whole genome Next Generation Sequencing and mapping on a contig genome assembly, complemented with Illumina design tools proved to be efficient in producing this GoatSNP50 chip. Advances in use of molecular markers are expected to accelerate goat genomic studies in coming years.
A European perspective on alternatives to animal testing for environmental hazard identification and risk assessment
Scholz, S. ; Sela, E. ; Blaha, L. ; Braunbeck, T. ; Galay-Burgos, M. ; Garcia-Franco, M. ; Guinea, J. ; Kluver, N. ; Schirmer, K. ; Tanneberger, K. ; Tobor-Kaplon, M. ; Witters, H. ; Belanger, S. ; Benfenati, E. ; Creton, S. ; Cronin, M.T.D. ; Eggen, R.I.L. ; Embry, M. ; Ekman, D. ; Gourmelon, A. ; Halder, M. ; Hardy, B. ; Hartung, T. ; Hubesch, B. ; Jungmann, D. ; Lampi, M.A. ; Lee, L. van; Leonard, M. ; Kuster, E. ; Lillicrap, A. ; Luckenbach, T. ; Murk, A.J. ; Navas, J.M. ; Peijnenburg, W. ; Repetto, G. ; Salinas, E. ; Schuurmann, G. ; Spielmann, H. ; Tollefsen, K.E. ; Walter-Rohde, S. ; Whale, G. ; Wheeler, J.R. ; Winter, M.J. - \ 2013
Regulatory Toxicology and Pharmacology 67 (2013). - ISSN 0273-2300 - p. 506 - 530.
zebrafish danio-rerio - plant-protection products - messenger-rna expression - adverse outcome pathways - acute fish toxicity - in-vitro - toxicological concern - disrupting chemicals - aquatic toxicity - aromatic-hydrocarbons
Tests with vertebrates are an integral part of environmental hazard identification and risk assessment of chemicals, plant protection products, pharmaceuticals, biocides, feed additives and effluents. These tests raise ethical and economic concerns and are considered as inappropriate for assessing all of the substances and effluents that require regulatory testing. Hence, there is a strong demand for replacement, reduction and refinement strategies and methods. However, until now alternative approaches have only rarely been used in regulatory settings. This review provides an overview on current regulations of chemicals and the requirements for animal tests in environmental hazard and risk assessment. It aims to highlight the potential areas for alternative approaches in environmental hazard identification and risk assessment. Perspectives and limitations of alternative approaches to animal tests using vertebrates in environmental toxicology, i.e. mainly fish and amphibians, are discussed. Free access to existing (proprietary) animal test data, availability of validated alternative methods and a practical implementation of conceptual approaches such as the Adverse Outcome Pathways and Integrated Testing Strategies were identified as major requirements towards the successful development and implementation of alternative approaches. Although this article focusses on European regulations, its considerations and conclusions are of global relevance
Demo niet kerende grondbewerking : Demonstraties door Derek van Balen
Swagemakers, J. ; Balen, D.J.M. van - \ 2011
cultivators - eggen - landbouwwerktuigen - grondbewerking - minimale grondbewerking - gebruikswaarde - akkerbouw - groenbemesters - harrows - farm machinery - tillage - minimum tillage - use value - arable farming - green manures
In het luzerneveld lichtte onderzoeker Derk van Balen de werking van de cultivators en schijveneg toe. „Deze machines voor niet kerende grondbewerkingen vragen minder brandstof dan bijvoorbeeld een rotorkopeg of een frees. Maar voor een goed resultaat is een tweede werkgang hier wel nodig.” De omstandigheden waren nog wat aan de natte kant waardoor de machines sneller dan gewenst vol liepen met grond.
Sol–gel immobilization of Alcalase from Bacillus licheniformis for application in the synthesis of C-terminal peptide amides
Corici, L.N. ; Frissen, A.E. ; Zoelen, D.J. van; Eggen, I.F. ; Peter, F. ; Davidescu, C.M. ; Boeriu, C.G. - \ 2011
Journal of Molecular Catalysis. B, Enzymatic 73 (2011)1-4. - ISSN 1381-1177 - p. 90 - 97.
organic-solvents - serine proteases - enzyme - stabilization - encapsulation - entrapment - stability - lipases - biocatalysts - activation
Alcalase 2.4L FG, a commercial preparation of Subtilisin A, was physically entrapped in glass sol–gel matrices using alkoxysilanes of different types mixed with tetramethoxysilane (TMOS). The materials were used for catalyzing C-terminal amidation of Z-Ala-Phe-OMe in a mixture of tert-butanol/DMF. From the screening of silane monomers in the sol–gel coating process, it was concluded that dimethyldimethoxysilane (DMDMOS) gave the best performance, and Alcalase immobilized therein exhibited the highest activity in the ammonolysis of Z-Ala-Phe-OMe. The percentage of protein immobilization was in the range of 68–98%, and total amidation activity of the immobilized Alcalase was up to 1.76 µmol/h/mg gel. We investigated the immobilization efficiency for a protein mass range of 2.8–9.7 mg per mmol total silanes, to determine the immobilization capacity of the biosilica support. The optimum enzyme loading capacity in the silica matrix was 115 mg/g dry silica xerogel (11.5%, w/w). The amount of the DMDMOS silicate was optimized by adjusting the molar ratio of silane mixture (DMDMOS and TMOS at 1:1). Biocatalyst sol–gel particles prepared at optimum immobilization conditions retained 100% of the original activity even after 14 cycles of repeated use. Reproducibility of the immobilization technique was also investigated by evaluating the catalytic efficiency of the obtained preparations. The thermal stability of the protease at 70 °C increased threefold upon entrapment in sol–gel materials, and twofold under storage for 50 days at ambient temperature.
Onkruid mechanisch de baas blijven
Bleeker, P.O. - \ 2011
Akker magazine 4 (2011)4. - ISSN 1875-9688 - p. 46 - 47.
onkruidbestrijding - akkerbouw - mechanische bestrijding - mechanisatie - landbouwwerktuigen - wiedmachines - schoffelen - eggen - wieden - weed control - arable farming - mechanical control - mechanization - farm machinery - rod weeders - hoeing - harrows - weeding
Akkerbouwers krijgen steeds minder chemische onkruidbestrijdingsmiddelen tot hun beschikking, zeker in kleinere teelten. Daarnaast groeit het areaal biologisch. Onkruidspecialist Piet Bleeker van het PPO zet daarom de ontwikkelingen in mechanische onkruidbestrijding op een rijtje.
Synthesis of Peptide Amides using Sol-Gel Immobilized Alcalase in Batch and Continuous Reaction System
Corici, L.N. ; Frissen, A.E. ; Zoelen, D.J. van; Eggen, I.F. ; Peter, F. ; Davidescu, C. ; Boeriu, C.G. - \ 2011
World Academy of Science, Engineering and Technology 5 (2011)4. - ISSN 2070-3740 - p. 794 - 799.
Two commercial proteases from Bacillus licheniformis (Alcalase 2.4 L FG and Alcalase 2.5 L, Type DX) were screened for the production of Z-Ala-Phe-NH2 in batch reaction. Alcalase 2.4 L FG was the most efficient enzyme for the C-terminal amidation of Z-Ala-Phe-OMe using ammonium carbamate as ammonium source. Immobilization of protease has been achieved by the sol-gel method, using dimethyldimethoxysilane (DMDMOS) and tetramethoxysilane (TMOS) as precursors (unpublished results). In batch production, about 95% of Z-Ala-Phe-NH2 was obtained at 30°C after 24 hours of incubation. Reproducibility of different batches of commercial Alcalase 2.4 L FG preparations was also investigated by evaluating the amidation activity and the entrapment yields in the case of immobilization. A packed-bed reactor (0.68 cm ID, 15.0 cm long) was operated successfully for the continuous synthesis of peptide amides. The immobilized enzyme retained the initial activity over 10 cycles of repeated use in continuous reactor at ambient temperature. At 0.75 mL/min flow rate of the substrate mixture, the total conversion of Z-Ala-Phe-OMe was achieved after 5 hours of substrate recycling. The product contained about 90% peptide amide and 10% hydrolysis byproduct.
Protease kinetics : selective hydrolysis of C-terminal tert-butyl esters of peptides by Alcalase immobilized as cross-linked enzyme aggregates
Corici, L. ; Frissen, A.E. ; Gini, F. ; Zoelen, D.J. van; Eggen, I.F. ; Boeriu, C.G. - \ 2010
Protease-catalyzed selective deprotection of C-terminal tert-butyl esters of peptides
Corici, L. ; Frissen, A.E. ; Gini, F. ; Zoelen, D.J. van; Eggen, I.F. ; Peter, F. ; Boeriu, C.G. - \ 2010
Optimized enzymatic synthesis of C-terminal peptide amides using subtilisin A from Bacillus licheniformis
Boeriu, C.G. ; Frissen, A.E. ; Boer, E. ; Kekem, C. van; Zoelen, D.J. van; Eggen, I.F. - \ 2010
Journal of Molecular Catalysis. B, Enzymatic 66 (2010)1-2. - ISSN 1381-1177 - p. 33 - 42.
amidation - ammonolysis - ammonia - amidase - esters - acids
A mild and efficient method for the conversion of C-terminal esters of side-chain protected peptides into an amide function via enzyme-catalysed ammonolysis in organic media with low water content is described. Subtilisin A, the alkaline serine protease from Bacillus licheniformis, was used as biocatalyst and ammonium carbamate as source of ammonia. Response surface methodology (RSM) and central composite design were employed to estimate the effects of reaction parameters such as molar ratio of ammonia source to peptide methyl ester (2:1–10:1), composition of the solvent system (ButOH/DMF, % v/v, 70:30–95:5) and water concentration (0.2–0.8%) at different temperatures (30–50 °C) for the preparation of Z-Ala-Phe-NH2 starting from Z-Ala-Phe-OMe. Optimum reaction conditions for maximum amide yield and minimum secondary hydrolysis were determined from cross-section analysis: temperature 30 °C, solvent composition ButOH/DMF 82.5:17.5 (v/v) containing 0.2% water (v/v) and molar ratio of ammonia source to peptide methyl ester of 10:1. The maximum yield of Z-Ala-Phe-NH2 was 87% after 21 h for a quantitative substrate conversion. The method proved to be generally applicable for the synthesis of C-terminal amides of dipeptides with different terminal amino acids and sequence.
Selective Enzymatic Modification Of C-Terminal Esters Of Peptides
Zoelen, D. van; Frissen, A.E. ; Boeriu, C.G. ; Eggen, I. - \ 2009
In: Program and Abstracts for the 21st American Peptide Symposium, Bloomington, Indiana, USA, - 12 June, 2009. - - p. 367 - 368.
Inventarisatie onkruidbesheersing in maïs : Invloed van het afschaffen van de cross-compliance regeling op de onkruidbestrijdingstrategieën in maïs
Zeeland, M.G. van; Spits, H.G. ; Kroonen-Backbier, B.M.A. ; Weide, R.Y. van der - \ 2009
Lelystad : PPO AGV - 29
maïs - onkruidbestrijding - mechanische bestrijding - pesticiden - eggen als grondbewerking - grondbewerking - inventarisaties - vragenlijsten - loonbedrijven - akkerbouw - maize - weed control - mechanical control - pesticides - harrowing - tillage - inventories - questionnaires - wage labour enterprises - arable farming
Maïs is het grootste akkerbouwmatig geteelde gewas in Nederland. De gewasbescherming richt zich voornamelijk op de ounkruidbestrijding. In 2005 is de cross compliance regeling door de overheid afgeschaft. (Die regeling hield in, dat maximaal 1 kg actieve stof / ha in combinatie met mechanische onkruidbestrijding). Om het effect van de afschaffing van de regeling na te gaan zijn in 2006 enquetes gehouden onder loonwerkers. Deze enquete is nu herhaald
Onkruidbestrijding, Demonstraties op de Biologische Velddag
Bleeker, P.O. - \ 2009
Ekoland 29 (2009)6. - ISSN 0926-9142 - p. 28 - 29.
biologische landbouw - onkruidbestrijding - landbouwwerktuigen - eggen - schoffels - onkruidwieders - akkerbouw - vollegrondsgroenten - organic farming - weed control - farm machinery - harrows - hoes - weeders - arable farming - field vegetables
Mechanische onkruidbestrijding is nog altijd erg belangrijk op biologische bedrijven met akkerbouw en groentegewassen. Steeds meer machines kan men hiervoor inzetten. Tussen de eg en de intrarijwieder van Garford is er veel mogelijk
Werken aan schoner oppervlaktewater in intensieve maïsteeltgebieden. Pilotstudie Maïscasus in de Hoge en Lage Raam in 2008
Backbier, B.M.A. ; Hulst, W. van der - \ 2009
Lelystad : PPO AGV - 66
zea mays - gewasbescherming - herbiciden - dosering - milieubescherming - grondbewerking - waterkwaliteit - waterverontreiniging - waterschappen - noord-brabant - zea mays - plant protection - herbicides - dosage - environmental protection - tillage - water quality - water pollution - polder boards - noord-brabant
De maïsteelt is een grote gebruiker van herbiciden en er zijn zelfs typische maïsteeltmiddelen. In heel beperkte mate worden zelfs herbiciden in zo’n mate gevonden, dat ecologische normen worden overschreden. Een werkgroep is opgezet om deze problematiek aan te pakken. In 2008 zijn de activiteiten gericht op waterschap Aa en Maas: één in het stroomgebied van de Hoge Raam (Zeeland en Langenboom) en één in het stroomgebied van de Lage Raam (St. Anthonis – Rijkevoort), beide hebben alleen gebiedseigen water. De waterkwaliteit kent dus geen invloed van buiten af. De gestelde doelen zijn: 1. Bezien of er maïsherbiciden in problematische gehalten (boven de MTR-waarden en boven de drinkwaternorm) voorkomen binnen de gebieden Hoge Raam en Lage Raam; 2. Het eventueel voorkomen van die middelen zien te verklaren vanuit een registratie van de gewasbeschermingspraktijk in de maïsteelt in betreffende gebieden; 3. Gebruik en emissie van middelen zien te beperken door alternatieven voorlichtend onder de aandacht te brengen; die alternatieven zijn eggen, schoffelen, LDS, druk en samenstelling onkruiden bepalen en hierop middelenkeuze en –dosering baseren, bij de keuze van middel ook score milieubelastingpunten volgens milieumeetlat meewegen, e.d.; 4. Puntemissies voorlichtend verminderen door checklist/enquête puntemissies met loonwerkers en zelfspuiters te doorlopen.
Application of proteases in the C-terminal modification of peptides
Gini, F. ; Eggen, I.F. ; Zoelen, D.J. van; Boeriu, C.G. - \ 2009
Chimica Oggi = Chemistry today 27 (2009)2. - ISSN 1973-8250 - p. 24 - 26.
alkaline protease - organic-solvents - resolution - esters
The high selectivity and the mild reaction conditions of enzymatic processes prompted their application in the synthesis of peptides, where selectivity is a feature of pivotal importance. Here we report the use of the serine protease subtilisin for the selective deprotection of C-terminal tert-butyl esters, achieved in good to quantitative yield for most of the natural amino acids. The same enzyme was active in the C-terminal amidation affording excellent yields with several peptides in the presence of a variety of amino sources. Subtilisin, finally, can also catalyse the transesterification of C-terminal primary esters. All the reactions are highly selective and neither side chains modifications nor N-terminus reactions have been observed. The endopeptidase activity, an important drawback in the use of proteases, was minimized upon extensive optimization of the reaction conditions.
Selective enzymatic hydrolysis of C-terminal tert-butyl esters of peptides
Boeriu, C.G. ; Eggen, I.F. ; Zoelen, D.J. van; Bours, G.H. - \ 2009
In: Peptides for youth : the proceedings of the 20th American Peptide Symposium / DelValle, S., Escher, E., Lubell, W.D., Berlin [etc.] : Springer (Advances in Experimental Medicine and Biology 611) - ISBN 9780387736563 - p. 115 - 116.
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