Staff Publications

Staff Publications

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    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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    Organische stofbalans Excel-applicatie : onderdeel van het project sturen van de N-mineralisatie met kennis over organische stof
    Zwart, K.B. ; Kikkert, A. ; Wolfs, A. ; Termorshuizen, A. ; Burgt, A. van der - \ 2013
    Kennisakker.nl 2013 (2013)17 juli.
    organische stof - berekening - bodembeheer - stikstof - mineralisatie - bodemvruchtbaarheid - akkerbouw - organic matter - calculation - soil management - nitrogen - mineralization - soil fertility - arable farming
    In opdracht van Productschap Akkerbouw is door het Louis Bolk Instituut, BLGG AgroXpertus, Alterra en HLB een applicatie ontwikkeld die snel en eenvoudig per teeltrotatie de OS-balans en stikstofmineralisatie in beeld brengt.
    Kosten-baten analyse over organische stof beheer : onderdeel van het project sturen van de N-mineralisatie met kennis over organische stof
    Zwart, K.B. ; Kikkert, A. ; Termorshuizen, A. ; Burgt, G.J. van der - \ 2013
    Kennisakker.nl 2013 (2013)18 juli.
    bemesting - organische stof - organische meststoffen - kosten-batenanalyse - akkerbouw - fertilizer application - organic matter - organic fertilizers - cost benefit analysis - arable farming
    Organische stof in de bodem staat sterk in de belangstelling. Organische stof is essentieel voor de levering van nutriënten en voor de bodemstructuur en daarmee ook voor de o.a. vochthuishouding en de bewerkbaarheid. Er heerst een vrij brede bezorgdheid dat het gehalte en de kwaliteit van organische stof in de bodem achteruit gaat. Uitgebreide analyses van de ontwikkelingen van het gehalte aan bodem-organische stof laten echter geen achteruitgang zien op landelijke of regionale schaal. Toch kan dat bij een individuele teler wel het geval zijn. Het blijft voor elke teler dan ook van groot belang om voor een goed organische stofbeheer te zorgen. Met die gedachte in het achterhoofd en met de wetenschap dat het gehalte aan organische stof maar langzaam verandert, heeft Productschap Akkerbouw een opdracht uitgezet om een eenvoudige organische stof balans voor de bodem te ontwikkelen met daaraan gekoppeld een kosten-baten analyse.
    Tien vragen en antwoorden over organische stof : onderdeel van het project sturen van de N-mineralisatie met kennis over organische stof
    Zwart, K.B. ; Kikkert, A. ; Wolfs, A. ; Termorshuizen, A. ; Burgt, G.J.H.M. van der - \ 2013
    Kennisakker.nl 2013 (2013)18 juli.
    organische stof - bodemvruchtbaarheid - bodemweerbaarheid - bemesting - bodemkwaliteit - akkerbouw - bodembeheer - organic matter - soil fertility - soil suppressiveness - fertilizer application - soil quality - arable farming - soil management
    Door middel van tien vragen en antwoorden is het belang van organische stof voor de bodemvruchtbaarheid beschreven. Wat is organische stof? Welke rol speelt organische stof in de bodem? Welke rol speelt organische stof in de bodemvruchtbaarheid? Welke rol speelt organische stof bij ziektewering? Wat is een organische stof balans van de bodem? Wat is effectieve organische stof? Neemt het organische stofgehalte af? Wat is de ideale organische stofgehalte? Hoe kun je het organische stofgehalte in de bodem verhogen? Kun je mineralisatie uit organische stof voorspellen?
    Sturen van de N-mineralisatie met kennis over organische stof
    Zwart, K.B. ; Wolfs, A. ; Kikkert, A. ; Termorshuizen, A. ; Burgt, G.J.H.M. van der - \ 2013
    Wijster : HLB - 11
    organische stof - stikstof - mineralisatie - bodemvruchtbaarheid - berekening - bemesting - bodembeheer - akkerbouw - organic matter - nitrogen - mineralization - soil fertility - calculation - fertilizer application - soil management - arable farming
    Stikstoflevering vanuit organische stof (OS) wordt belangrijker naarmate de bemestingsnormen strakker worden. Dit project kent drie fasen met de volgende doelen. Fase I: de bestaande kennis over organische stof en stikstofmineralisatie te ontsluiten voor zowel telers als voorlichters, Fase II: een functioneel ontwerp van een adviesmodule op te leveren waarmee de stikstofbenutting vanuit de bodem kan worden gekwantificeerd bij diverse managementmaatregelen rond organische stof. Gedurende het project is besloten om dit te wijzigen in een werkende module. Fase III: de opgeleverde adviesmodule te testen in de praktijk op een viertal locaties en te demonstreren op een 20-tal praktijkbedrijven.
    Tien vragen en antwoorden over organische stof
    Zwart, K.B. ; Wolfs, A. ; Kikkert, A. ; Termorshuizen, A. ; Burgt, G.J.H.M. van der - \ 2013
    Wijster : HLB - 8
    organische stof - bodemvruchtbaarheid - bodemweerbaarheid - bodemkwaliteit - bemesting - akkerbouw - bodembeheer - organic matter - soil fertility - soil suppressiveness - soil quality - fertilizer application - arable farming - soil management
    Er is reeds veel informatie beschikbaar over het onderwerp ‘organische stof in de bodem’ In dt rapport is een deel van die informatie nog eens samengevat in de vorm van 10 vragen en antwoorden. Wat is organische stof? Welke rol speelt organische stof in de bodem? Welke rol speelt organische stof in de bodemvruchtbaarheid? Welke rol speelt organische stof bij ziektewering? Wat is een organische stof balans van de bodem? Wat is effectieve organische stof? Neemt het organische stofgehalte af? Wat is de ideale organische stofgehalte? Hoe kun je het organische stofgehalte in de bodem verhogen? Kun je mineralisatie uit organische stof voorspellen?
    De organische stof balans met de te verwachten stikstoflevering per teeltrotatie : opzet en gebruikswijze van een rekenmodule
    Zwart, K.B. ; Wolfs, A. ; Kikkert, A. ; Termorshuizen, A. ; Burgt, G.J.H.M. van der - \ 2013
    Wijster : HLB - 17
    organische stof - stikstof - mineralisatie - berekening - bodembeheer - bodemvruchtbaarheid - akkerbouw - organic matter - nitrogen - mineralization - calculation - soil management - soil fertility - arable farming
    Organische stof speelt een hoofdrol in de vruchtbaarheid van de bodem. In opdracht van Productschap Akkerbouw is door het Louis Bolk Instituut, BLGG AgroXpertus, Alterra en HLB een applicatie ontwikkeld die snel en eenvoudig per teeltrotatie de organische stofbalans en stikstofmineralisatie in beeld brengt. In dit rapport wordt de opzet en de gebruikswijze van de applicatie kort uiteengezet.
    Organische stof: wat levert het op? : kosten en baten van organische stof voor de akkerbouwer
    Zwart, K.B. ; Kikkert, A. ; Burgt, G.J.H.M. van der; Termorshuizen, A. - \ 2013
    Masterplan Mineralenmanagement
    kosten-batenanalyse - organische stof - bodembeheer - bodemvruchtbaarheid - akkerbouw - bemesting - cost benefit analysis - organic matter - soil management - soil fertility - arable farming - fertilizer application
    Met die gedachte in het achterhoofd en met de wetenschap dat het gehalte aan organische stof maar langzaam verandert, heeft Productschap Akkerbouw enige tijd geleden een opdracht uitgezet bij een consortium bestaande uit Alterra, HLB-BV, Louis Bolk Instituut en BLGG Research om een eenvoudige organische stof balans voor de bodem te ontwikkelen met daaraan gekoppeld een kosten-baten analyse. Deze brochure geeft informatie over de kosten-baten van organische stof.
    Sturen van de N-mineralisatie met kennis over organische stof
    Zwart, K.B. ; Kikkert, A. ; Wolfs, A. ; Termorshuizen, A. ; Burgt, G.J.H.M. van der - \ 2013
    Kennisakker.nl 2013 (2013)18 juli.
    akkerbouw - bemesting - stikstof - mineralisatie - organische stof - arable farming - fertilizer application - nitrogen - mineralization - organic matter
    Doordat gebruiksnormen de maximale bemesting met stikstof bepalen, wordt het steeds belangrijker om goed te kunnen voorspellen hoeveel stikstof de bodem levert. Wanneer de voorspelbaarheid hoog is, kan maximaal rekening worden gehouden met de levering van stikstof uit de bodem, wat kosten bespaart en uitspoeling van N reduceert.
    Tomato spotted wilt virus glycoproteins exhibit trafficking and localization signals that are functional in mammalian cells
    Kikkert, M. ; Verschoor, A. ; Kormelink, R. ; Rottier, P. ; Goldbach, R. - \ 2001
    Journal of Virology 72 (2001). - ISSN 0022-538X - p. 1004 - 1012.
    The glycoprotein precursor (G1/G2) gene of tomato spotted wilt virus (TSWV) was expressed in BHK cells using the Semliki Forest virus expression system. The results reveal that in this cell system, the precursor is efficiently cleaved and the resulting G1 and G2 glycoproteins are transported from the endoplasmic reticulum (ER) to the Golgi complex, where they are retained, a process that could be blocked by tunicamycin. Expression of G2 alone resulted in transport to and retention in the Golgi complex, albeit less efficient, suggesting that G2 contains a Golgi retention signal. G1 alone was retained in the ER, irrespective of whether it contained the precursor's signal sequence or its own N-terminal hydrophobic sequence. Coexpression of G1 and G2 from separate gene constructs resulted in rescue of efficient G1 transport, as the proteins coaccumulated in the Golgi complex, indicating that their interaction is essential for proper targeting to this organelle. The results demonstrate that transport and targeting of the plant TSWV glycoproteins in mammalian BHK cells are strikingly similar to those of animal-infecting bunyavirus glycoproteins in mammalian cells. The observations are likely to reflect the dual tropism of TSWV, which replicates both in its plant host and in its animal (thrips) vector.
    Trafficking and localization of tomato spotted wilt virus glycoproteins in mammalian cells
    Kikkert, M. ; Kormelink, R. ; Rottier, P. ; Goldbach, R. - \ 2000
    In: Negative Strand Viruses : 11th International Conference on Negative Strand Viruses, Quebec 2000. - Quebec : [s.n.], 2000 - p. 58 - 58.
    TSWV morphogenesis and the role of the viral glycoproteins therein
    Kikkert, M. ; Kormelink, R. ; Goldbach, R.W. - \ 1999
    In: XIth International Congress of Virology : 9 - 13 August 1999, Sydney, Australië : book of abstracts / [by the] International Union of Microbiological Societies (IUMS) [1999]. - [S.l.] : [ s.n.], 1999 - p. 26 - 26.
    Involvement of the Golgi-complex in envelopment of Tomato Spotted Wilt Virus
    Kikkert, M. ; Lent, J.W.M. van; Kormelink, R.J.M. ; Goldbach, R.W. - \ 1999
    In: 9th International Congress on Molecular Plant-Microbe Interactions : 25 - 30 July 1999, Amsterdam, the Netherlands ; book of abstracts. - [S.l.] : [s.n.], 1999 - p. 139 - 139.
    Tomato spotted wilt virus particle morphogenesis in plant cells
    Kikkert, M. ; Lent, J.W.M. van; Storms, M. ; Bodegom, P. ; Kormelink, R.J.M. ; Goldbach, R.W. - \ 1999
    Journal of Virology 73 (1999)3. - ISSN 0022-538X - p. 2288 - 2297.
    A model for the maturation of tomato spotted wilt virus (TSWV) particles is proposed, mainly based on results with a protoplast infection system, in which the chronology of different maturation events could be determined. By using specific monoclonal and polyclonal antisera in immunofluorescence and electron microscopy, the site of TSWV particle morphogenesis was determined to be the Golgi system. The viral glycoproteins G1 and G2 accumulate in the Golgi prior to a process of wrapping, by which the viral nucleocapsids obtain a double membrane. In a later stage of the maturation, these doubly enveloped particles fuse to each other and to the endoplasmic reticulum to form singly enveloped particles clustered in membranes. Similarities and differences between the maturation of animal-infecting (bunya)viruses and plant-infecting tospoviruses are discussed.
    Role of the envelope glycoproteins in the infection cycle of tomato spotted wilt virus
    Kikkert, M. - \ 1999
    Agricultural University. Promotor(en): R.W. Goldbach; R. Kormelink. - S.l. : Kikkert - ISBN 9789058080585 - 117
    tomatenbronsvlekkenvirus - plantenvirussen - plantenziekteverwekkers - plantenziekten - infectie - glycoproteïnen - tomato spotted wilt virus - plant viruses - plant pathogens - plant diseases - infection - glycoproteins

    Tomato spotted wilt virus (TSWV) forms the type member of the genus Tospovirus , which today harbors more than twelve different species. TSWV is able to infect an enormous variety of different plants, to which it often causes devastating effects, resulting in severe economical losses. Among the plant viruses, TSWV and the other tospoviruses form a distinct group. Taxonomically, they surprisingly do not belong to a plant virus family, but to a virus family which further consists of animal-infecting viruses, the Bunyaviridae . Consequently, they harbor features that are more common to animal-infecting viruses than to plant viruses. The most eye-catching animal-infecting virus-like feature of the tospoviruses is their envelope, in which two viral surface glycoproteins are embedded, denoted G1 and G2. These surface glycoproteins are designed for interaction with receptors, an important step in the infection of animals, but useless in the infection of plants. The plant-infecting tospoviruses are transmitted by thrips, in which they also replicate, and for the entry and circulation of the virus through this insect the glycoproteins are essential. This ensures their continues presence despite their lack of function during the infection of plants. The structure and function of the TSWV glycoproteins during infection in plants and insects form the subject of this thesis, of which the contents will be summarized in the next paragraphs, and also visually represented in Fig. 1.

    First develop the tools...

    Although the TSWV glycoproteins do not have a crucial function in the plant, they do play an essential role in the formation of virus particles. At the onset of these studies, however, no clear view of this morphogenesis process was available, so it was the obvious first goal to unravel this process for TSWV in plants. In the past, virus associated structures observed during the infection of whole plants were reported, but thirty five years of observations had not resulted in a clear model of the particle morphogenesis. Useful antibodies against the separate TSWV proteins had not been available, and most importantly, a system in which a synchronous infection could be investigated lacked, so that interpretation of the chrology of the events in the morphogenesis had been difficult. Chapter 2 of this thesis describes the development of a protoplast infection system for TSWV, which enabled the study of a synchronous TSWV infection in plant cells. Using newly produced antibodies against the viral glycoproteins together with antibodies against the nucleoprotein, it could be shown that a full, synchronous, TSWV infection is achieved, by the PEG-mediated inoculation of freshly isolated Nicotiana rustica protoplasts with freshly (and quickly) isolated TSWV particles. Similar inoculation of Vigna unguiculata protoplasts did not result in a full infection, since the production of enveloped particles was hampered due to low expression of the viral glycoproteins.

    ...to reveal the essence of TSWV particle making...

    Using the system, based on N. rustica protoplasts, the different virus associated structures could be assigned a chronological position in the morphogenesis process. This view of the chronology of the process revealed that the so-called paired parrallel membranes and doubly enveloped particles form essential intermediates in the process, which precede the accumulation of singly enveloped particles in the lumen of ER membranes. Using specific antibodies against the TSWV structural proteins, as well as antibodies against plant cell organels, the model could be completed ( Chapter 3 ). TSWV structural components, nucleocapsids as well as glycoproteins, accumulate at Golgi membranes, which are consequently modified to form the paired parrallel membranes. Doubly enveloped particles are formed by the so-called "wrapping" of these viral glycoprotein containing membranes around nucleocapsid cores, a process unique among plant viruses. The subsequent step is the fusion of these doubly enveloped particles with each other and specifically with ER membranes. This results in the formation of singly enveloped particles that accumulate within the ER.

    ...and then look what causes all this...

    After the complete model of the morphogenesis became available, the next step was to investigate what (molecular) features of especially the glycoproteins regulate the process. An important observation in the morphogenesis process is the apparent accumulation of viral glycoproteins in the Golgi system. This may, analogous to other enveloped viruses, be caused by the specific targeting of the glycoproteins to this organel due to a retention signal. The trafficking and retention behavior of TSWV glycoproteins was investigated in mammalian cells, the results of which are described in Chapter 4 . TSWV G1 and G2 accumulate in the Golgi system when expression together, which indeed implicates that at least one of the proteins must harbor a Golgi retention signal. Separate expression of G1 and G2 revealed that the retention signal is present in G2. G1 on its own is transport incompetent, but this can be rescued by the co-expression with G2, which suggests that G1 is dependent on, and interacts with G2 during transport and retention. These molecular features, identified in mammalian cells, are most probably also functional in plant cells, causing the observed accumulation of glycoproteins in the plant Golgi system during infection. The TSWV glycoproteins thereby show their crucial role in directing the particle morphogenesis process.

    ...and how these particles interact with thrips.

    Once the particles are formed and accumulated inside ER membranes, they await the uptake by the thrips vector to be transferred to another plant. Earlier research has shown that between this uptake and the release of virus there is replication and circulation of TSWV in the thrips. However, nothing was known about the molecular interactions between TSWV proteins and proteins of the thrips during this process. In Chapter 5 an overlay blot technique was used to investigate the possible binding of TSWV structural proteins with thrips proteins, that could be potential receptors involved in entry or circulation of TSWV. A 94 kDa thrips protein was identified, displaying specific binding to TSWV G2 protein. This 94 kDa protein was found in known vectors of TSWV, and also in a non-vector thrips species, albeit it not in the larval stages of the latter. Although a receptor is anticipated in the gut of the vectoring insects, the 94 kDa protein is not found there. It is however present in all other parts of the thrips body, suggesting that it may have a role during the replication and circulation of the virus.

    Fig. 1
    Fig. 1
    Diagram of TSWV infection in a plant cell, indicating the scope of the experimental chapters of this thesis

    Analyses of NSM as plant virus movement protein of tomato spotted wilt virus (TSWV).
    Storms, M. ; Prins, M. ; Kikkert, M. ; Wetering, F. van de; Schoot, C. van der; Kormelink, R. ; Lent, J. van; Goldbach, R. - \ 1998
    In: 4th International Symposium on Tospoviruses and Thrips in Floral and Vegetable Crops, Wageningen, The Netherlands - p. 8 - 8.
    Trafficking and localization of tomato spotted wilt virus glycoproteins: implications for particle morphogenesis.
    Kikkert, M. ; Lent, J. van; Storms, M. ; Kormelink, R. ; Goldbach, R. - \ 1998
    In: 4th International Symposium on Tospoviruses and Thrips in Floral and Vegetable Crops, Wageningen, The Netherlands - p. 6 - 7.
    Binding of tomato spotted wilt virus to a 94-kDa thrips protein.
    Kikkert, M. ; Meurs, C. ; Wetering, F. van de; Dorfmueller, S. ; Peters, D. ; Kormelink, R. ; Goldbach, R. - \ 1998
    Phytopathology 88 (1998). - ISSN 0031-949X - p. 63 - 69.
    Characterization of RNA-mediated resistance to tomato spotted wilt virus in transgenic tobacco plants expressing NSm gene sequences.
    Prins, M. ; Kikkert, M. ; Ismayada, C. ; Grauw, W. de; Haan, P. de; Goldbach, R. - \ 1997
    Plant Molecular Biology 33 (1997)2. - ISSN 0167-4412 - p. 235 - 243.
    Transgenic Nicotiana tabacum plants expressing RNA sequences of the tomato spotted wilt virus NSM gene, which encodes the putative viral movement protein, were found to be highly resistant to infection with the virus. Expression of untranslatable as well as anti-sense RNA of the NSM gene resulted in resistance levels as high as those in plants expressing translatable RNA sequences. For all three types of transgenic plants resistance levels of up to 100% were reached in the S2 progeny. These results indicate that the resistance mediated by the NSM gene is accomplished by expression of transcripts rather than protein in transgenic plants, similar to previously observed N gene-mediated resistance. Protoplast inoculations revealed that resistant plants expressing NSM are, in contrast to N transgenic resistant plants, not resistant at the cellular level. This suggests the RNA-mediated resistance mechanism against TSWV targets viral mRNAs rather than the viral genome.
    Tospoviral gene expression in plant and animal single-cell systems.
    Kikkert, M. ; Storms, M. ; Kormelink, R. ; Peters, D. ; Goldbach, R. - \ 1997
    In: American Society for Virology, 16th Annual Meeting, Bozeman, USA. W32-08 - p. 152 - 152.
    A protoplast system for studying tomato spotted wilt virus infection.
    Kikkert, M. ; Poelwijk, F. van; Karssies, W. ; Bloksma, H. ; Storms, M. ; Lent, J. van; Kormelink, R. ; Goldbach, R. - \ 1997
    Journal of General Virology 78 (1997). - ISSN 0022-1317 - p. 1755 - 1763.
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