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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Clonal expansion of a virulent Streptococcus suis serotype 9 lineage distinguishable from carriage subpopulations
Willemse, Niels ; Ark, Kees C.H. van der; Stockhofe-Zurwieden, Norbert ; Smith, Hilde ; Picavet, Daisy I. ; Solt-Smits, Conny van; Wisselink, Henk J. ; Schultsz, Constance ; Greeff, Astrid de - \ 2019
Scientific Reports 9 (2019)1. - ISSN 2045-2322

Streptococcus suis is a porcine pathogen, causing severe invasive infections. S. suis serotype 9 is increasingly causing disease in Dutch and Chinese pig herds, but it is unknown whether all serotype 9 isolates are equally virulent and markers that can identify virulent strains are not available. Therefore, discrimination between virulent isolates and carriage isolates typically not associated with disease, is currently not possible. We collected tonsillar S. suis isolates from 6 herds not previously diagnosed with S. suis infections, and clinical S. suis isolates of previously diseased pigs. We confirmed the virulence of a virulent type strain and one representative clinical isolate, and the lack of virulence of two carriage isolates, in a pig infection model. Phylogenetic analysis of whole genome sequences of 124 isolates resulted in 10 groups, of which two were almost uniquely populated by clinical isolates. The population structure of S. suis serotype 9 appears highly diverse. However, analysis of the capsule loci sequences showed variation in a single region which fully correlated with a virulent genotype. Transmission electron microscopy suggested differences in capsule thickness between carriage and clinical genotypes. In conclusion, we found that that the S. suis serotype 9 population in the Netherlands is diverse. A distinct virulence-associated lineage was identified and could be discriminated based on the capsule locus sequence. Whilst the difference in virulence cannot be directly attributed to the DNA sequence, the correlation of capsule locus sequence with virulence could be used in the development of diagnostic tests to identify potential virulent S. suis serotype 9 in pigs.

Comparison of Two Sustainable Counter Electrodes for Energy Storage in the Microbial Rechargeable Battery
Molenaar, Sam D. ; Elzinga, Margo ; Willemse, Sonja G. ; Sleutels, Tom ; Heijne, Annemiek ter; Buisman, Cees J.N. - \ 2019
ChemElectroChem 6 (2019)9. - ISSN 2196-0216 - p. 2464 - 2473.
bioelectrochemical systems - energy storage - microbial electrochemical technology - microbial electrosynthesis - microbial rechargeable batteries

Recently, the microbial rechargeable battery (MRB) has been proposed as a potentially sustainable and low-cost electrical energy storage technology. In the MRB, bioelectrochemical CO 2 reduction and subsequent product oxidation has successfully been combined in one integrated system. However, finding a suitable counter electrode is hindering its further development. In this work, we have tested two alternative counter electrodes in duplicate-namely, i) oxygen/water and ii) a capacitive electrode-for use in the MRB platform. During daily charge/discharge cycling over periods of 11 to 15 days, experimentally obtained energy efficiencies of 25 and 3.7 % were reported when using the capacitive and the oxygen/water electrodes, respectively. Large overpotentials, resulting in a voltage efficiency of 15 % and oxygen crossover leading to coulombic efficiencies of 25 % caused the considerably lower efficiency for the oxygen/water systems, despite the theoretical higher voltage efficiency. Although the capacitive electrode equipped systems performed better, energy density is limited by the operational potential window within which capacitive systems can operate reliably. Microbial community analysis revealed dominant presence of Geobacter in the bioanode and Selenomonadales in the biocathode. These results do not necessarily bring practical application of the MRB closer, but they do provide new insights in the working principle of this new technology.

Praktijkgericht onderzoek
Ros, Anje ; Bakx, Anouke ; Brok, Perry den - \ 2018
In: Kennisbasis lerarenopleiders ketern 5: onderzoek in de lerarenopleidingen / Boei, Fer, Willemse, Martijn, Werkendam : VELON - p. 59 - 72.
Het belang van praktijkgericht onderzoek is zowel voor het onderwijsveld, als voor de lerarenopleidingen sinds de eeuwwisseling sterk toegenomen. Over de term praktijkgericht onderzoek en de positionering ervan, bestaat echter veel onduidelijkheid. In dit hoofdstuk maken we onderscheid tussen praktijkgericht onderzoek, onderzoek gericht op het verbeteren van de brede onderwijspraktijk en praktijkonderzoek, (docent-)onderzoek gericht op de verbetering van het onderwijs op de eigen school of opleiding. Bij praktijkgericht onderzoek onderscheiden we vier stappen: vraagarticulatie, kennisproductie, kennistransfer en kennisgebruik. Bij praktijkonderzoek belichten we drie functies van onderzoek in de school, de feedbackfunctie, de dialoogfunctie en de ontwerpfunctie. Voor beide typen onderzoek benoemen we diverse condities die gerealiseerd moeten zijn, voordat er sprake kan zijn van daadwerkelijke impact in de onderwijspraktijk. Een van de voorwaarden is een onderzoekende houding van leraren. Voor de ontwikkeling van een onderzoekende houding van aankomende leraren is de voorbeeldrol van opleidingsdocenten cruciaal.
Inter- and intracellular colonization of Arabidopsis roots by endophytic actinobacteria and the impact of plant hormones on their antimicrobial activity
Meij, Anne van der; Willemse, Joost ; Schneijderberg, Martinus A. ; Geurts, René ; Raaijmakers, Jos M. ; Wezel, Gilles P. van - \ 2018
Antonie van Leeuwenhoek: : Nederlandsch tijdschrift voor hygiëne, microbiologie en serologie 111 (2018)5. - ISSN 0003-6072 - p. 679 - 690.
Cryptic antibiotics - Electron microscopy - Plant hormone - Plant–microbe interactions - Streptomyces
Many actinobacteria live in close association with eukaryotes such as fungi, insects, animals and plants. Plant-associated actinobacteria display (endo)symbiotic, saprophytic or pathogenic life styles, and can make up a substantial part of the endophytic community. Here, we characterised endophytic actinobacteria isolated from root tissue of Arabidopsis thaliana (Arabidopsis) plants grown in soil from a natural ecosystem. Many of these actinobacteria belong to the family of Streptomycetaceae with Streptomyces olivochromogenes and Streptomyces clavifer as well represented species. When seeds of Arabidopsis were inoculated with spores of Streptomyces strain coa1, which shows high similarity to S. olivochromogenes, roots were colonised intercellularly and, unexpectedly, also intracellularly. Subsequent exposure of endophytic isolates to plant hormones typically found in root and shoot tissues of Arabidopsis led to altered antibiotic production against Escherichia coli and Bacillus subtilis. Taken together, our work reveals remarkable colonization patterns of endophytic streptomycetes with specific traits that may allow a competitive advantage inside root tissue.
Streptococcal Adhesin P (SadP) contributes to Streptococcus suis adhesion to the human intestinal epithelium
Ferrando, Maria Laura ; Willemse, Niels ; Zaccaria, Edoardo ; Pannekoek, Yvonne ; Ende, Arie van der; Schultsz, Constance - \ 2017
PLoS ONE 12 (2017)4. - ISSN 1932-6203

Background Streptococcus suis is a zoonotic pathogen, causing meningitis and septicemia. We previously demonstrated that the gastrointestinal tract (GIT) is an entry site for zoonotic S. suis infection. Here we studied the contribution of Streptococcal adhesin Protein (SadP) to hostpathogen interaction at GIT level. Methods SadP expression in presence of Intestinal Epithelial Cells (IEC) was compared with expression of other virulence factors by measuring transcript levels using quantitative Real Time PCR (qRT-PCR). SadP variants were identified by phylogenetic analysis of complete DNA sequences. The interaction of SadP knockout and complementation mutants with IEC was tested in vitro. Results Expression of sadP was significantly increased in presence of IEC. Sequence analysis of 116 invasive strains revealed five SadP sequence variants, correlating with genotype. SadP1, present in zoonotic isolates of clonal complex 1, contributed to binding to both human and porcine IEC and translocation across human IEC. Antibodies against the globotriaosylceramide Gb3/CD77 receptor significantly inhibited adhesion to human IEC. Conclusion SadP is involved in the host-pathogen interaction in the GIT. Differences between SadP variants may determine different affinities to the Gb3/CD77 host-receptor, contributing to variation in adhesion capacity to host IEC and thus to S. suis zoonotic potential.

An emerging zoonotic clone in the Netherlands provides clues to virulence and zoonotic potential of Streptococcus suis
Willemse, N. ; Howell, K.J. ; Weinert, L.A. ; Heuvelink, A. ; Pannekoek, Y. ; Wagenaar, J.A. ; Smith, H.E. ; Ende, A. Van Der; Schultsz, C. - \ 2016
Scientific Reports 6 (2016). - ISSN 2045-2322

Streptococcus suis is a zoonotic swine pathogen and a major public health concern in Asia, where it emerged as an important cause of bacterial meningitis in adults. While associated with food-borne transmission in Asia, zoonotic S. suis infections are mainly occupational hazards elsewhere. To identify genomic differences that can explain zoonotic potential, we compared whole genomes of 98 S. suis isolates from human patients and pigs with invasive disease in the Netherlands, and validated our observations with 18 complete and publicly available sequences. Zoonotic isolates have smaller genomes than non-zoonotic isolates, but contain more virulence factors. We identified a zoonotic S. suis clone that diverged from a non-zoonotic clone by means of gene loss, a capsule switch, and acquisition of a two-component signalling system in the late 19th century, when foreign pig breeds were introduced. Our results indicate that zoonotic potential of S. suis results from gene loss, recombination and horizontal gene transfer events.

Recombinant culicoides obsoletus complex allergens stimulate antigen-specific T cells on insect bite hypersensitive Shetland ponies in vitro
Meulenbroeks, C. ; Meide, N.M.A. van der; Willemse, T. ; Rutten, V. ; Tijhaar, E.J. - \ 2015
Veterinary Dermatology 26 (2015)6. - ISSN 0959-4493 - p. 467 - e109.
Background Ponies may suffer from Insect bite hypersensitivity (IBH), an allergic IgE-mediated pruritic skin disorder, induced by allergens from biting midges of the Culicoides spp. Hypothesis/Objectives To determine whether recombinant Culicoides obsoletus allergens are able to activate T cells of ponies exposed to C. obsoletus and whether these allergen-specific responses differ between IBH-affected and healthy ponies. Animals Ten IBH-affected Shetland ponies and 10 age-matched healthy controls taken from the same stables, to ensure similar exposure to midges. Method Peripheral blood mononuclear cells (PBMC) were cultured with two different pools of recombinant C. obsoletus complex allergens to expand the allergen-specific T cells. These PBMC cultures were subsequently co-cultured with mature dendritic cells (DCs) loaded with the same antigens. Induction of Th1, Th2 and regulatory T (Treg) cells in these DC/PBMC co-cultures was assessed by analysis of IFN-¿, IL-4, IL-10 and FoxP3 expression levels using quantitative RT-PCR and phenotyping by flow cytometry. Results Recombinant C. obsoletus allergens increased IFN-¿ mRNA expression levels, percentages of IFN-¿ expressing (Th1) cells and CD25highFoxP3+IL-10+ Tregs compared to unstimulated DC/PBMC co-cultures. Stimulation of IL-4 expressing Th2 cells by the recombinant allergens was far less pronounced. The DC/PBMC co-cultures did not reveal significant differences between healthy and IBH-affected ponies for any of the analysed parameters, except for higher IL-4 mRNA levels in IBH affected ponies after stimulation with one of the two allergen pools. Conclusion and clinical importance The recombinant C. obsoletus complex allergens can stimulate antigen-specific Th1 and IL10 producing Treg cells and are therefore promising candidates for the immunotherapy of IBH.
Allergen-specific cytokine polarization protects shetland ponies against culicoides obsoletus-induced insect bite hypersensitivity
Meulenbroeks, C. ; Lugt, J.J. van der; Meide, N.M.A. van der; Willemse, T. ; Rutten, V.P.M.G. ; Zaiss, D.M.W. - \ 2015
PLoS ONE 10 (2015)4. - ISSN 1932-6203 - 12 p.
e-bearing cells - mast-cells - british-columbia - friesian horses - skin biopsies - sweet itch - ige - antibodies - tolerance - immunotherapy
The immunological mechanisms explaining development of an allergy in some individuals and not in others remain incompletely understood. Insect bite hypersensitivity (IBH) is a common, seasonal, IgE-mediated, pruritic skin disorder that affects considerable proportions of horses of different breeds, which is caused by bites of the insect Culicoides obsoletus (C. obsoletus). We investigated the allergen-specific immune status of individual horses that had either been diagnosed to be healthy or to suffer of IBH. Following intradermal allergen injection, skin biopsies were taken of IBH-affected and healthy ponies and cytokine expression was determined by RT-PCR. In addition, allergen-specific antibody titers were measured and cytokine expression of in vitro stimulated, allergen-specific CD4 T-cells was determined. 24 hrs after allergen injection, a significant increase in mRNA expression of the type-2 cytokine IL-4 was observed in the skin of IBH-affected Shetland ponies. In the skin of healthy ponies, however, an increase in IFN¿ mRNA expression was found. Analysis of allergen-specific antibody titers revealed that all animals produced allergen-specific antibodies, and allergen-specific stimulation of CD4 T-cells revealed a significant higher percentage of IFN¿-expressing CD4 T-cells in healthy ponies compared to IBH-affected ponies. These data indicate that horses not affected by IBH, in contrast to the so far established dogma, are not immunologically ignorant but have a Th1-skewed allergen-specific immune response that appears to protect against IBH-associated symptoms. To our knowledge this is the first demonstration of a natural situation, in which an allergen-specific immune skewing is protective in an allergic disorder.
Seasonal differences in cytokine expression in the skin of Shetland ponies suffering from insect bite hypersensitivity
Meulenbroeks, C. ; Meide, N.M.A. van der; Zaiss, D.M.W. ; Oldruitenborgh-Oosterbaan, M.M.S. ; Lugt, J.J. van der; Smak, J. ; Rutten, V.P.M.G. ; Willemse, T. - \ 2013
Veterinary Immunology and Immunopathology 151 (2013)1-2. - ISSN 0165-2427 - p. 147 - 156.
culicoides-hypersensitivity - messenger-rna - icelandic horses - igg antibodies - sweet itch - allergy - netherlands - cells - flea - identification
Insect bite hypersensitivity (IBH) in horses is a seasonal, IgE-mediated, pruritic skin disorder primarily caused by Culicoides spp. We hypothesize that a mixed Th2/Th1-type immune status, off season, alters into Th2-dominated immune reactivity in the skin of IBH-affected ponies in the IBM season. To study these immune response patterns Culicoides-specific IgE levels, skin histopathology and cytokine and transcription factor mRNA expression (IL4, IL10, IL13, IFN gamma, FoxP3 and CD3(zeta)) in lesional and non-lesional skin of ponies affected by IBH in the IBH season were compared with those of the same animals off season and those in skin of healthy ponies in both seasons. The present study revealed a significantly higher histopathology score in lesional skin of affected ponies than in non-lesional skin and skin of healthy ponies in the IBH season. Culicoides obsoletus-specific IgE serum levels of ponies with IBH were significantly higher than those in healthy ponies in both seasons. Interestingly, C. obsoletus-specific IgE serum levels within each group were the same in the IBH season and off season. The expression of IL4, IL13 and IFN gamma mRNA in skin biopsies in the IBH season showed a significant increase compared to off season in both skin derived from healthy control ponies (n = 14) as well as in lesional and in non-lesional skin from IBH-affected animals (n = 17). This apparently general up-regulation of cytokine expression during the IBH season directly correlated with an increased CD3(zeta) mRNA expression in the skin, indicating an overall increased T cell influx during the summer months. The only significant difference observed between lesional skin from IBH-affected animals as compared to skin from healthy control animals in the IBH season was a lower expression of IL13/CD3(zeta) in the affected animals. FoxP3 and IL10 levels were unaffected, except for a lower expression of FoxP3 in healthy control skin in the IBM season as compared to off season, In addition, the increased level of C obsoletus-specific IgE did not correlate with higher histological scores in LE skin. In summary, our data indicate a general immune activation in the skin of both healthy and IBH-affected ponies during the IBH season that potentially obscures the Culicoides-specific immune reaction pattern, even in lesional skin of IBH-affected animals. (C) 2012 Elsevier B.V. All rights reserved.
Krimpbeleid met sociale media : sturen met sociaal kapitaal op maatschappelijke energie
During, R. ; Willemse, R. - \ 2013
Wageningen : Wageningen University (Zo doen wij dat hier! dl. 5) - ISBN 9789461737076 - 56
sociale netwerken - sociaal kapitaal - sociale participatie - plaatselijk bestuur - overheidsbeleid - samenleving - innovaties - nederland - social networks - social capital - social participation - local government - government policy - society - innovations - netherlands
Naarmate het besef groeit dat de zorgsamenleving onbetaalbaar wordt onder invloed van de demografische en economische trends, komt sociale en maatschappelijke innovatie steeds nadrukkelijker op de agenda. In alle sectoren van het rijksbeleid wordt gesproken van vermaatschappelijking als belangrijke strategie en doorsnijdend thema. Het besef dat marktwerking en new public management (de overheidsdienst als bedrijf) de consumptieve houding van burgers hebben versterkt, ligt ten grondslag aan deze strategie. Het maatschappelijk initiatief is er nog steeds en kan als een soort humuslaag de voedingsbodem vormen van een actieve samenleving waarin de overheid verantwoordelijk is voor de infrastructuur, en burgers c.q. het maatschappelijk middenveld voor specifieke doelen. In het Noord-Groningse dorpje Holwierde kan de dorpswinkel open blijven, omdat verstandelijk gehandicapten bij wijze van dagbesteding meehelpen: een mooi voorbeeld van zo’n sociale innovatie in die humuslaag. In dit essay gaan we na hoe die humuslaag is ingebed in sociale-media-communicatiepraktijken en welke nieuwe mogelijkheden dit kan bieden voor het beleid inzake krimp. Hiervoor hebben we onderzoek gedaan, waarbij in de pilotgebieden Burgerschap in Krimp van BZK en de Landelijke Vereniging van Kleine Kernen (LVKK) is gekeken naar discussies over krimp en zelforganisatie.
Sociale media: nieuwe wegen naar sociale innovatie. Een verkenning van de rol van internet en de sociale media bij het ontstaan van sociale innovatie.
Salverda, I.E. ; Jagt, P.D. van der; Willemse, R. ; Onwezen, M.C. ; Top, J. - \ 2013
Wageningen : Alterra, Wageningen-UR
Options for closing the phosphorus cycle in agriculture : assessment of options for Northwest Europe and the Netherlands
Lesschen, J.P. ; Kolk, J.W.H. van der; Dijk, K.C. van; Willemse, J. - \ 2013
Wageningen : Wettelijke Onderzoekstaken Natuur & Milieu (WOt-werkdocument 353) - 47
veehouderij - dierhouderij - veevoeder - dierlijke meststoffen - fosfor - nutrientenbeheer - kringlopen - mestoverschotten - gesloten systemen - landbouwbeleid - regionaal landbouwbeleid - noordwest-europa - livestock farming - animal husbandry - fodder - animal manures - phosphorus - nutrient management - cycling - manure surpluses - closed systems - agricultural policy - regional agricultural policy - northwestern europe
This study assessed which options are available for closing the feed-manure phosphorus cycle in agriculture and their contribution to the reduction of the P surplus and P use efficiency. This was assessed at a national scale for the Netherlands as well as a regional scale for Northwest Europe. No export of animal products, with as a consequence the reduction in livestock numbers, is most effective in reducing external P inputs. An effective option that is easier to implement is the reduction in P excretion through changes in the feed intake. For Nortwest Europe the combination of all five options can lead to a reduction of external P inputs of about 50%. For the Netherlands the combination of the options result in a reduction in external P inputs of 35% and a reduction of the manure export of 26%. The effectiveness of large scale manure treatment in the Netherlands is limited
Sociale media: nieuwe wegen naar sociale innovatie
Salverda, I.E. ; Jagt, P.D. van der; Willemse, R. ; Onwezen, M.C. ; Top, J.L. - \ 2013
[S.l.] : S.n. (Zo doen wij dat hier! 4)
sociale netwerken - sociale verandering - hedendaagse samenleving - communicatie - netwerken (activiteit) - innovaties - internet - social networks - social change - contemporary society - communication - networking - innovations
Hoewel de rol en impact van internet en de sociale media in de samenleving algemeen worden aangenomen, is het nog niet duidelijk of en hoe het communiceren en delen van informatie via internet en de sociale media bijdragen aan het ontstaan van sociale innovatie. Hoofdvragen van deze verkenning zijn daarom: Bieden de sociale media nieuwe wegen waarlangs groepen mensen komen tot uitwisseling en samenwerking voor maatschappelijke vernieuwing? Op welke wijze ontstaan er via de sociale media sociale interacties, uitwisseling en samenwerking zodat sociale innovatie kan ontstaan? En hoe beïnvloeden deze online uitwisseling en samenwerking de rol en organisatie van de gevestigde orde? Het ontbreekt hierover aan een overzicht van (wetenschappelijke) literatuur, maar ook aan inzicht over wat er in de praktijk op het sociale web plaatsvindt. Vandaar dat we aan de hand van literatuur en praktijkvoorbeelden onderzoeken welke rol communicatie en interactie via de sociale media spelen of kunnen spelen bij vernieuwingen vanuit de maatschappij. Met deze verkenning zetten we hierin een eerste stap.
Een mooier landschap met minder plagen : de baten van aantrekkelijke akkerranden wegen ruimschoots op tegen de kosten
Alebeek, F.A.N. van; Vijn, M.P. ; Willemse, J. ; Rijn, P. van - \ 2012
Ekoland 32 (2012)5. - ISSN 0926-9142 - p. 26 - 27.
functionele biodiversiteit - agrobiodiversiteit - akkerranden - plagenbestrijding - bevordering van natuurlijke vijanden - agrarisch natuurbeheer - landschapsbeheer - functional biodiversity - agro-biodiversity - field margins - pest control - encouragement - agri-environment schemes - landscape management
Onderzoek laat zien dat hoe beter we akkerranden verbinden met kleine landschapselementen in het omringende landschap, hoe beter de natuurlijke plaagbeheersing vanuit die akkerranden kan werken. Om het netwerk aaneengesloten te krijgen is samenwerking nodig tussen verschillende partijen in het gebied.
Eindrapportage FAB2 2008-2011 : functionele agro biodiversiteit
Geus, J. de; Gurp, H. van; Alebeek, F.A.N. van; Bos, M. ; Janmaat, L. ; Molendijk, L.P.G. ; Rijn, P. van; Schaap, B.F. ; Visser, A. ; Vlaswinkel, M.E.T. ; Wal, E. van der; Willemse, J. ; Zanen, M. - \ 2011
’s-Hertogenbosch : ZLTO Projecten - 47
agrobiodiversiteit - functionele biodiversiteit - akkerranden - akkerbouw - plaagbestrijding met natuurlijke vijanden - bevordering van natuurlijke vijanden - gewasbescherming - landschap - bodembeheer - bodembiologie - bodemweerbaarheid - agro-biodiversity - functional biodiversity - field margins - arable farming - augmentation - encouragement - plant protection - landscape - soil management - soil biology - soil suppressiveness
In het door LTO Noord, ZLTO en LLTB geïnitieerde project Functionele Agrobiodiversiteit (FAB2) is de afgelopen jaren ervaring opgedaan met het slim benutten van levende organismen om tot duurzame landbouw te komen. Deze aanpak vraagt om een aantal aanpassingen in de bedrijfsvoering en het landschap, zodat deze organismen kunnen overleven en hun nuttige werk kunnen doen. Het nut van akkerranden hiervoor is aangetoond. In FAB2 is verkend of er slim gebruik kan worden gemaakt van landschapselementen door aanpassing van het beheer. Ook is gezocht naar eenvoudige methoden (scouting) om te bepalen of de natuur voldoende in staat is om het (luizen)probleem op te lossen. Tot slot werd gezocht naar strategieën voor het duurzaam gebruik van de bodem, zoals niet-kerende grondbewerking.
FAB en gewasbescherming - Het belang van goed waarnemen.
Visser, A. ; Vlaswinkel, M.E.T. ; Wal, E. van der; Willemse, J. ; Alebeek, F.A.N. van - \ 2011
Lelystad : PPO AGV
akkerbouw - plaagbestrijding met natuurlijke vijanden - agrobiodiversiteit - gewasbescherming - functionele biodiversiteit - bevordering van natuurlijke vijanden - insectenplagen - natuurlijke vijanden - arable farming - augmentation - agro-biodiversity - plant protection - functional biodiversity - encouragement - insect pests - natural enemies
In combinatie met bloemrijke akkerranden biedt scouting een goede mogelijkheid om het gebruik van insecticiden tegen luizen in granen en consumptieaardappelen te minimaliseren. In de toekomst zullen, onder andere door de hogere milieueisen, steeds minder gewasbeschermingsmiddelen toegelaten zijn. Het stimuleren van natuurlijke vijanden zal een steeds belangrijkere rol gaan spelen in het voorkomen van plagen in het gewas. Goed scouten is daarbij belangrijk. De tijd die nodig is voor een keer scouten ligt gemiddeld op ongeveer 20 minuten per perceel van ca. 5 hectare. Afhankelijk van het gewas, groeistadium en de luisdruk is het nodig om per seizoen 4-7 keer te scouten, om een goed beeld te krijgen en te houden van de situatie in het gewas
FAB en akkerranden voor natuurlijke plaagbeheersing
Rijn, P. van; Willemse, J. ; Alebeek, F.A.N. van - \ 2011
Lelystad : PPO AGV
akkerbouw - plaagbestrijding met natuurlijke vijanden - akkerranden - agrobiodiversiteit - bevordering van natuurlijke vijanden - gewasbescherming - kosten - bloemen - functionele biodiversiteit - arable farming - augmentation - field margins - agro-biodiversity - encouragement - plant protection - costs - flowers - functional biodiversity
Akkerranden om de natuurlijke plaagbeheersing te ondersteunen staan centraal in het FAB project. Terwijl meerjarige akkerranden een schuilplaats en leefgebied kunnen bieden als er geen gewas op de akker staat, zijn éénjarige bloemenranden weer meer geschikt om vliegende, natuurlijke vijanden tijdens het groeiseizoen het noodzakelijke voedsel te bieden in de vorm van stuifmeel en nectar.
FAB en omgeving - Het belang van groene en blauwe netwerken.
Alebeek, F.A.N. van; Schaap, B.F. ; Willemse, J. ; Rijn, P. van - \ 2011
Lelystad : PPO AGV
akkerbouw - akkerranden - plaagbestrijding met natuurlijke vijanden - agrobiodiversiteit - landschapsbeheer - wegbermen - slootkanten - onderhoud - functionele biodiversiteit - gewasbescherming - bevordering van natuurlijke vijanden - arable farming - field margins - augmentation - agro-biodiversity - landscape management - roadsides - ditch banks - maintenance - functional biodiversity - plant protection - encouragement
Sinds een aantal jaren doen agrarische ondernemers ervaring op met de toepassing van Functionele Agrobiodiversiteit (FAB) om ziekten en plagen in cultuurgewassen te beheersen. Er zijn pilots in de Hoeksche Waard in Zuid-Holland, in Zeeland, Noord Brabant en Flevoland waarin gebruik gemaakt wordt van het landschap en haar biodiversiteit voor de onderdrukking van ziekten en plagen. In de loop van 2011 is in de Hoeksche Waard een pilot tot stand gekomen voor FAB-vriendelijk beheer van enkele dijken, wegbermen en bijbehorende sloottaluds door het waterschap Hollandse Delta (WSHD). Het waterschap gaat monitoren wat de kosten en besparingen in deze pilot kunnen zijn en hoe het beheer praktisch in de bestekken past.
Positive control of cell division: FtsZ is recruited by SsgB during sporulation of Streptomyces
Willemse, J. ; Borst, J.W. ; Waal, E. de; Bisseling, T. ; Wezel, G.P. van - \ 2011
Genes and Development 25 (2011)1. - ISSN 0890-9369 - p. 89 - 99.
escherichia-coli - coelicolor a3(2) - protein ftsz - assembly dynamics - bacillus-subtilis - crystal-structure - ring structure - living cells - growth - gene
In bacteria that divide by binary fission, cell division starts with the polymerization of the tubulin homolog FtsZ at mid-cell to form a cell division scaffold (the Z ring), followed by recruitment of the other divisome components. The current view of bacterial cell division control starts from the principle of negative checkpoints that prevent incorrect Z-ring positioning. Here we provide evidence of positive control of cell division during sporulation of Streptomyces, via the direct recruitment of FtsZ by the membrane-associated divisome component SsgB. In vitro studies demonstrated that SsgB promotes the polymerization of FtsZ. The interactions are shown in vivo by time-lapse imaging and Förster resonance energy transfer and fluorescence lifetime imaging microscopy (FRET-FLIM), and are corroborated independently via two-hybrid studies. As determined by fluorescence recovery after photobleaching (FRAP), the turnover of FtsZ protofilaments increased strongly at the time of Z-ring formation. The surprising positive control of Z-ring formation by SsgB implies the evolution of an entirely new way of Z-ring control, which may be explained by the absence of a mid-cell reference point in the long multinucleoid hyphae. In turn, the localization of SsgB is mediated through the orthologous SsgA, and premature expression of the latter is sufficient to directly activate multiple Z-ring formation and hyperdivision at early stages of the Streptomyces cell cycle
Toward in vitro fertilization in Brachiaria spp.
Dusi, D. ; Alves, E.R. ; Willemse, M.T.M. ; Falcao, R. ; Valle, C.B. do; Carneiro, V.T.C. - \ 2010
Sexual Plant Reproduction 23 (2010)3. - ISSN 0934-0882 - p. 187 - 197.
pollen-tube - brizantha poaceae - chromosome-number - embryo sac - colchicine - decumbens - guidance - maize - ovule
Brachiaria are forage grasses widely cultivated in tropical areas. In vitro pollination was applied to accessions of Brachiaria spp. by placing pollen of non-dehiscent anthers on a solid medium near isolated ovaries. Viability and in vitro germination were tested in order to establish good conditions for pollen development. Comparing sexual to apomictic plants, apomictic pollen has more abortion after meiosis during the microspore stage and a lower viability and, of both types, only some plants have sufficient germination in a high sugar concentration. Using in vitro pollination with the sexual plant, the pollen tube penetrates into the nucellus and micropyle, but the embryo sac degenerates and collapses. In the apomictic B. decumbens, in vitro pollination leads to the transfer of the sperm nuclei into the egg cell and the central cell. The results are discussed according to normal fertilization and barriers in sexual and apomictic plants.
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