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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    Interactions between formulation and spray drying conditions related to survival of Lactobacillus plantarum WCFS1
    Perdana, J.A. ; Fox, M.B. ; Siwei, C. ; Boom, R.M. ; Schutyser, M.A.I. - \ 2014
    Food Research International 56 (2014). - ISSN 0963-9969 - p. 9 - 17.
    glass-transition temperature - membrane phase-behavior - lactic-acid bacteria - flow-cytometry - industrial applications - dairy ingredients - osmotic-stress - water activity - rhamnosus gg - gel phase
    Protective solid carriers are commonly added to probiotic cultures prior to drying. Their formulation is not trivial and depends on the drying conditions applied. In this study, we systematically investigated the influence of formulation parameters on the survival of Lactobacillus plantarum WCFS1 after drying. Low molecular weight carbohydrates (less than 2 kDa) with high glass transition temperatures provided the highest level of protection at both low (25 degrees C) and high (50 degrees C or higher) drying temperatures. Low molecular weight carbohydrates may provide stabilization by closely interacting with the lipid bilayer of the cell membranes. Meanwhile, carbohydrates with high glass transition temperatures probably provide stabilization via fixation of the cells in a glassy powder. Furthermore, adequate amounts of solid carrier are required to sufficiently stabilize the cells during drying. During drying, crystallization of solid carriers may occur. Depending on the crystal geometry, crystallization can be either beneficial (e.g. with mannitol or sorbitol) or detrimental (e.g. with lactose) to cell survival. Finally, the effect of formulation on cell viability during storage was studied. A decimal reduction time of approximately 300 days was observed when spray dried L. plantarum WCFS1 was stored at temperatures below 40 degrees C. The outcome of this study was used as a basis to construct a generalized diagram to indicate the combinations of formulation and drying conditions to maximally retain viability and operate dryers at high efficiency. (C) 2013 Elsevier Ltd. All rights reserved.
    Adjustment of host cells for accommodation of symbiotic bacteria: vacuole defunctionalization, HOPS suppression, and TIP1g retargeting in Medicago
    Gavrin, A.Y. ; Kaiser, B.N. ; Geiger, D. ; Tyerman, S.D. ; Wen, Z. ; Bisseling, T. ; Fedorova, E.E. - \ 2014
    The Plant Cell 26 (2014)9. - ISSN 1040-4651 - p. 3809 - 3822.
    major intrinsic proteins - pea root-nodules - n-2-fixing symbiosomes - endoplasmic-reticulum - legume symbiosis - osmotic-stress - ph homeostasis - h+-atpase - arabidopsis - aquaporins
    In legume–rhizobia symbioses, the bacteria in infected cells are enclosed in a plant membrane, forming organelle-like compartments called symbiosomes. Symbiosomes remain as individual units and avoid fusion with lytic vacuoles of host cells. We observed changes in the vacuole volume of infected cells and thus hypothesized that microsymbionts may cause modifications in vacuole formation or function. To examine this, we quantified the volumes and surface areas of plant cells, vacuoles, and symbiosomes in root nodules of Medicago truncatula and analyzed the expression and localization of VPS11 and VPS39, members of the HOPS vacuole-tethering complex. During the maturation of symbiosomes to become N2-fixing organelles, a developmental switch occurs and changes in vacuole features are induced. For example, we found that expression of VPS11 and VPS39 in infected cells is suppressed and host cell vacuoles contract, permitting the expansion of symbiosomes. Trafficking of tonoplast-targeted proteins in infected symbiotic cells is also altered, as shown by retargeting of the aquaporin TIP1g from the tonoplast membrane to the symbiosome membrane. This retargeting appears to be essential for the maturation of symbiosomes. We propose that these alterations in the function of the vacuole are key events in the adaptation of the plant cell to host intracellular symbiotic bacteria.
    Effects of light, hydropriming and abiotic stress on seed germination, and shoot and root growth of pyrethrum (Tanacetum cinerariifolium
    Li, J. ; Jongsma, M.A. ; Wang, C.Y. - \ 2011
    Industrial Crops and Products 34 (2011)3. - ISSN 0926-6690 - p. 1543 - 1549.
    improve germination - hydration treatment - osmotic-stress - drought stress - salt stress - water - temperature - management - asteraceae - tolerance
    Poor germination and seedling establishment are major problems in arid and semi-arid environments, and these characteristics are considered to be important factors in later plant growth and yield. Laboratory experiments were conducted on freshly harvested pyrethrum (Tanacetum cinerariifolium) seeds to investigate the effects of light (influenced by the seeding method) and seed hydropriming on germination, and shoot and root growth at 25 °C. Exposure to light could reduce germination from 52% to 22% and increase the mean germination time (MGT) from 7 to 12 days. The responses of hydroprimed and unprimed seeds to salt and drought stress were determined at osmotic potentials of 0 (distilled water), -0.3, -0.6, -0.9, -1.2 MPa in NaCl and PEG6000. Seed germination and seedling growth were inhibited by increasing salt and drought stress. The germination percentage of unprimed seeds was reduced from 52% to 16% in -1.2 MPa NaCl, and no seeds germinated at osmotic potentials =-0.9 MPa PEG. Both shoot and root growth were inhibited at osmotic potentials =-0.9 MPa NaCl and =-0.6 MPa PEG. Hydropriming shortened the delay of MGT at all osmotic potentials, and improved the germination percentage in distilled water (from 52% to 59%) and resistance to salt stress with nearly double germination (from 16% to 29%) at the highest salt concentration. When non-germinated seeds were transferred to distilled water after 20 days of incubation in total up to 12–15% of NaCl and 25–27% of PEG stressed seeds did not recover. These results show that the inhibition of the germination and seedling growth at the same osmotic potential of NaCl and PEG resulted from drought stress rather than salt toxicity, and that hydropriming is an effective tool to improve the quality of pyrethrum seeds.
    Novel SigB regulation modules of Gram-positive bacteria involve the use of complex hybrid histidine kinases
    Been, M.W.H.J. de; Francke, C. ; Siezen, R.J. ; Abee, T. - \ 2011
    Microbiology 157 (2011)1. - ISSN 1350-0872 - p. 3 - 12.
    general stress-response - 2-component signal-transduction - bacillus-subtilis - streptomyces-coelicolor - transcription factor - energy stress - phosphatase 2c - osmotic-stress - pathway - protein
    A common bacterial strategy to cope with stressful conditions is the activation of alternative sigma factors that control specific regulons enabling targeted responses. In the human pathogen Bacillus cereus, activation of the major stress-responsive sigma factor sB is controlled by a signalling route that involves the multi-sensor hybrid histidine kinase RsbK. RsbK-type kinases are not restricted to the B. cereus group, but occur in a wide variety of other bacterial species, including members of the the low-GC Gram-positive genera Geobacillus and Paenibacillus as well as the high-GC actinobacteria. Genome context and protein sequence analyses of 118 RsbK homologues revealed extreme variability in N-terminal sensory as well as C-terminal regulatory domains and suggested that RsbK-type kinases are subject to complex fine-tuning systems, including sensitization and desensitization via methylation and demethylation within the helical domain preceding the H-box. The RsbK-mediated stress-responsive sigma factor activation mechanism that has evolved in B. cereus and the other species differs markedly from the extensively studied and highly conserved RsbRST-mediated sB activation route found in Bacillus subtilis and other low-GC Gram-positive bacteria. Implications for future research on sigma factor control mechanisms are presented and current knowledge gaps are briefly discussed.
    Sugar-Mediated Acclimation: The Importance of Sucrose Metabolism in Meristems
    Carpentier, S.C. ; Vertommen, A. ; Swennen, R. ; Witters, E. ; Fortes, C. ; Souza, M.T. ; Panis, B. - \ 2010
    Journal of Proteome Research 9 (2010)10. - ISSN 1535-3893 - p. 5038 - 5046.
    cell-suspension cultures - growing potato-tubers - low internal oxygen - chenopodium-rubrum - gene-expression - osmotic-stress - banana musa - synthase - plants - cryopreservation
    We have designed an in vitro experimental setup to study the role of sucrose in sugar-mediated acclimation of banana meristems using established highly proliferating meristem cultures. It is a first step toward the systems biology of a meristem and the understanding of how it can survive severe abiotic stress. Using the 2D-DIGE proteomic approach and a meristem-specific EST library, we describe the long-term acclimation response of banana meristems (after 2, 4, 8, and 14 days) and analyze the role of sucrose in this acclimation by setting up a control, a sorbitol, and a sucrose acclimation treatment over time. Sucrose synthase is the dominant enzyme for sucrose breakdown in meristem tissue, which is most likely related to its lower energy consumption. Metabolizing sucrose is of paramount importance to survive, but the uptake of sugar and its metabolism also drive respiration, which may result in limited oxygen levels. According to our data, a successful acclimation is correlated to an initial efficient uptake of sucrose and subsequently a reduced breakdown of sucrose and an induction of fermentation likely by a lack of oxygen.
    1H-NMR study of the impact of high pressure and thermal processing on cell membrane integrity of onions
    Gonzalez, M.E. ; Barrett, D.M. ; McCarthy, M.J. ; Vergeldt, F.J. ; Gerkema, E. ; Matser, A.M. ; As, H. van - \ 2010
    Journal of Food Science 75 (2010)7. - ISSN 0022-1147 - p. E417 - E425.
    spin-spin relaxation - mushrooms agaricus-bisporus - nuclear-magnetic-resonance - water diffusion - lactobacillus-plantarum - vacuolar symplast - osmotic-stress - maize roots - pfg-nmr - tissue
    Proton nuclear magnetic resonance (1H-NMR) relaxometry was used to study the effects of high pressure and thermal processing on membrane permeability and cell compartmentalization, important components of plant tissue texture. High pressure treated onions were subjected to pressure levels from 20 to 200 MPa at 5 min hold time at initial temperatures of 5 and 20 °C. Thermally treated onions were exposed for 30 min at temperatures from 40 to 90 °C. Loss of membrane integrity was clearly shown by changes in transverse relaxation time (T2) of water at temperatures of 60 °C and above. Destabilization effects on membranes exposed to high pressure were observed at 200 MPa as indicated by T2 measurements and cryo-scanning electron microscopy (Cryo-SEM). T2 relaxation successfully discriminated different degrees of membrane damage based on the T2 shift of the vacuolar component. Analyses of the average water self-diffusion coefficient indicated less restricted diffusion after membrane rupture occurred in cases of severe thermal treatments. Milder processing treatments yielded lower average diffusion coefficients than the controls. 1H-NMR proved to be an effective method for quantification of cell membrane damage in onions and allowed for the comparison of different food processes based on their impact on tissue integrity
    Comparatiave analysis of the grain proteome fraction in barley genotypes with contrasting salinity tolerance during germination
    Witzel, K. ; Weidner, A. ; Surabhi, G.K. ; Varshney, R.K. ; Kunze, G. ; Buck-Sorlin, G.H. ; Börner, A. ; Mock, H.P. - \ 2010
    Plant, Cell & Environment 33 (2010)2. - ISSN 0140-7791 - p. 211 - 222.
    abiotic stress-response - quantitative trait loci - salt tolerance - osmotic-stress - comparative transcriptome - heading date - dehydrogenase - gene - rice - resistance
    In the present paper, we based a search for candidates underlying different levels of salinity tolerance during germination in the Oregon Wolfe Barley mapping population (DOM × REC) by proteomic profiling of the mature grain of lines showing differing levels of salinity tolerance. By contrasting the parents DOM and REC, displaying divergent stress responses, and two tolerant and two sensitive segregants, six protein spots were identified that showed a differential abundance between the tolerant and the sensitive lines. The tolerant lines expressed a higher level of 6-phosphogluconate dehydrogenase and glucose/ribitol dehydrogenase (Glc/RibDH). Both proteins were heterologously over-expressed in an osmo-sensitive yeast strain and over-expression of Glc/RibDH resulted in an enhanced ability of yeast transformants to grow on salt containing media. A quantitative trait locus (QTL) analysis of the population germinating at different salt concentrations led to the identification of two chromosome regions on 5H and one on 7H associated with salt stress response. A dense barley transcript map was employed to map the genomic region of all identified proteins. Two of these, heat-shock protein 70 and Glc/RibDH, co-localized with the identified QTL on chromosome 5H. The putative functional role of the candidates is discussed
    Quantitative permeability imaging of plant tissues
    Sibgatullin, T. ; Vergeldt, F.J. ; Gerkema, E. ; As, H. van - \ 2010
    European Biophysics Journal 39 (2010)4. - ISSN 0175-7571 - p. 699 - 710.
    pulsed-field gradient - time-dependent diffusion - nuclear-magnetic-resonance - water self-diffusion - membrane-permeability - pfg nmr - osmotic-stress - porous-media - yeast-cells - echo nmr
    A method for mapping tissue permeability based on time-dependent diffusion measurements is presented. A pulsed field gradient sequence to measure the diffusion encoding time dependence of the diffusion coefficients based on the detection of stimulated spin echoes to enable long diffusion times is combined with a turbo spin echo sequence for fast NMR imaging (MRI). A fitting function is suggested to describe the time dependence of the apparent diffusion constant in porous (bio-)materials, even if the time range of the apparent diffusion coefficient is limited due to relaxation of the magnetization. The method is demonstrated by characterizing anisotropic cell dimensions and permeability on a subpixel level of different tissues of a carrot (Daucus carota) taproot in the radial and axial directions
    SodERF3, a novel sugarcane ethylene responsive factor (ERF), enhances salt and drought tolerance when overexpressed in tobacco plants
    Trujillo, L.E. ; Sotolongo, M. ; Menéndez, C. ; Ochogavía, M.E. ; Coll, Y. ; Hernández, I. ; Borrás-Hidalgo, O. ; Thomma, B.P.H.J. ; Vera, P. ; Hernández, L. - \ 2008
    Plant and Cell Physiology 49 (2008)4. - ISSN 0032-0781 - p. 512 - 525.
    transcription factor gene - element-binding factors - disease resistance - low-temperature - abscisic-acid - arabidopsis-thaliana - signal-transduction - pathogen infection - stress responses - osmotic-stress
    The molecular signals and pathways that govern biotic and abiotic stress responses in sugarcane are poorly understood. Here we describe SodERF3, a sugarcane (Saccharum officinarum L. cv Ja60-5) cDNA that encodes a 201-amino acid DNA-binding protein that acts as a transcriptional regulator of the ethylene responsive factor (ERF) superfamily. Like other ERF transcription factors, the SodERF3 protein binds to the GCC box, and its deduced amino acid sequence contains an N-terminal putative nuclear localization signal (NLS). In addition, a C-terminal short hydrophobic region that is highly homologous to an ERF-associated amphiphilic repression-like motif, typical for class II ERFs, was found. Northern and Western blot analysis showed that SodERF3 is induced by ethylene. In addition, SodERF3 is induced by ABA, salt stress and wounding. Greenhouse-grown transgenic tobacco plants (Nicotiana tabacum L. cv. SR1) expressing SodERF3 were found to display increased tolerance to drought and osmotic stress.
    MgHog1 regulates dimorphism and pathogenicity in the fungal wheat pathogen Mycosphaerella graminicola
    Mehrabi, R. ; Zwiers, L.H. ; Waard, M. de; Kema, G.H.J. - \ 2006
    Molecular Plant-Microbe Interactions 19 (2006)11. - ISSN 0894-0282 - p. 1262 - 1269.
    activated protein-kinase - candida-albicans - osmotic-stress - saccharomyces-cerevisiae - glycerol accumulation - neurospora-crassa - hydrogen-peroxide - hog1 gene - yeast - homolog
    The dimorphic ascomycete pathogen Mycosphaerella graminicola switches from a yeastlike form to an infectious filamentous form that penetrates the host foliage through stomata. We examined the biological function of the mitogenactivated protein kinase¿encoding gene MgHog1 in M. graminicola. Interestingly, MgHog1 mutants were unable to switch to filamentous growth on water agar that mimics the nutritionally poor conditions on the foliar surface and, hence, exclusively developed by a yeastlike budding process. Consequently, due to impaired initiation of infectious germ tubes, as revealed by detailed in planta cytological analyses, the MgHog1 mutants failed to infect wheat leaves. We, therefore, conclude that MgHog1 is a new pathogenicity factor involved in the regulation of dimorphism in M. graminicola. Furthermore, MgHog1 mutants are osmosensitive, resistant to phenylpyrrole and dicarboximide fungicides, and do not melanize
    Survival, elongation, and elevated tolerance of Salmonella enterica serovar Enteritidis at reduced water activity
    Kieboom, J. ; Kusumaningrum, H.D. ; Tempelaars, M.H. ; Hazeleger, W.C. ; Abee, T. ; Beumer, R.R. - \ 2006
    Journal of Food Protection 69 (2006)11. - ISSN 0362-028X - p. 2681 - 2686.
    osmotic-stress - cell-division - single-cell - typhimurium - microorganisms - temperatures - bacteria - glycine - heat - acid
    Growing microorganisms on dry surfaces, which results in exposure to low water activity (aw), may change their normal morphology and physiological activity. In this study, the morphological changes and cell viability of Salmonella enterica serovar Enteritidis challenged to low aw were analyzed. The results indicated that exposure to reduced aw induced filamentation of the cells. The amount of filamentous cells at aw 0.94 was up to 90% of the total number of cells. Surviving filamentous cells maintained their membrane integrity after exposure to low aw for 21 days. Furthermore, cells prechallenged to low aw, obtained with an ionic humectant, demonstrated higher resistance to sodium hypochlorite than control cells. These resistant cells are able to survive disinfection more efficiently and can therefore cause contamination of foods coming in contact with surfaces. This points to the need for increased attention to cleaning of surfaces in household environments and disinfection procedures in processing plants
    DNA psi-condensation and reentrant decondensation: Effect of the PEG degree of polymerization
    Ramos, J.E.B. ; Vries, R.J. de; Neto, J.R. - \ 2005
    The Journal of Physical Chemistry Part B: Condensed Matter, Materials, Surfaces, Interfaces & Biophysical 109 (2005)49. - ISSN 1520-6106 - p. 23661 - 23665.
    circular-dichroism - osmotic-stress - transition - forces - phase
    ¿-Condensation of DNA fragments of about 4 kbp was induced by poly(ethylene glycol) (PEG), with degrees of polymerization ranging from 45 to 182, and univalent salt (NaCl). Using circular dichroism spectroscopy, we were able to accurately determine the critical amount of PEG needed to induce condensation, as a function of the NaCl concentration. A significant dependence on the PEG degree of polymerization was found. Phase boundaries determined for the multimolecular condensation were very similar to those observed previously for the monomolecular collapse, with two asymptotic regimes at low and high salt concentrations. We analyze our data using a theoretical model that properly takes into account both the polyelectrolyte nature of the DNA and the liquid crystallinity of the condensed phase. The model assumes that all PEG is excluded from the condensates and shows reentrant decondensation only at low salt. We also systematically study reentrant decondensation and find a very strong dependence on PEG molecular weight. At low PEG molecular weight, decondensation occurs at relatively low concentrations of PEG, and over a wide range of salt concentrations. This suggests that in the reentrant decondensation the flexible polymers used are not completely excluded from the condensed phase
    Aquaporins of the PIP2 class are required for efficient anther dehiscence in tobacco
    Bots, M.L. ; Vergeldt, F.J. ; Wolters-Arts, M. ; Weterings, K. ; As, H. van; Mariani, C. - \ 2005
    Plant Physiology 137 (2005)3. - ISSN 0032-0889 - p. 1049 - 1056.
    jasmonic acid biosynthesis - membrane-permeability - arabidopsis-thaliana - brassica-oleracea - channel proteins - gene-expression - osmotic-stress - male-sterility - water - plants
    Several processes during sexual reproduction in higher plants involve the movement of water between cells or tissues. Before flower anthesis, anther and pollen dehydration takes place before the release of mature pollen at dehiscence. Aquaporins represent a class of proteins that mediates the movement of water over cellular membranes. Aquaporins of the plasmamembrane PIP2 family are expressed in tobacco (Nicotiana tabacum) anthers and may therefore be involved in the movement of water in this organ. To gain more insight into the role these proteins may play in this process, we have analyzed their localization using immunolocalizations and generated plants displaying RNA interference of PIP2 aquaporins. Our results indicate that PIP2 protein expression is modulated during anther development. Furthermore, in tobacco PIP2 RNA interference plants, anther dehydration was slower, and dehiscence occurred later when compared with control plants. Together, our results suggest that aquaporins of the PIP2 class are required for efficient anther dehydration prior to dehiscence.
    Glycerol dehydrogenase, encoded by gldB is essential to osmotolerance in Aspergillus nidulans
    Vries, R.P. de; Flitter, S.J. ; Vondervoort, P.J.I. van de; Chaveroche, M.K. ; Fontaine, T. ; Fillinger, S. ; Ruijter, G.J.G. ; Enfert, C. d'; Visser, J. - \ 2003
    Molecular Microbiology 49 (2003)1. - ISSN 0950-382X - p. 131 - 141.
    saccharomyces-cerevisiae - glycerol-3-phosphate dehydrogenase - 3-phosphate dehydrogenase - pyruvate-kinase - osmotic-stress - niger - yeast - growth - gene - expression
    We have characterized the Aspergillus nidulans gldB gene encoding a NADP(+) -dependent glycerol dehydrogenase. A basal expression level was observed for gldB , which increased significantly under conditions of hyper-osmotic shock (1 M NaCl). Growth of strains in which gldB was disrupted was severely reduced on plates containing 1% glucose and 1 M NaCl, but these strains were able to grow on plates containing 1 M NaCl and 1% glycerol, arabitol, mannitol or erythritol. Uptake of these polyols compensated for the inability of the gldB disruptants to produce glycerol. Presence of 1% glucose in these plates prevented growth restoration by all the polyols tested with the exemption of glycerol, indicating that uptake of mannitol, arabitol and erythritol is subject to glucose repression, whereas uptake of glycerol is significantly less or not repressed. No intracellular glycerol dehydrogenase activity could be detected in the gldB disruption strains. Intracellular glycerol levels in these strains were strongly decreased compared to wild type, whereas intracellular mannitol, erythritol and arabitol levels were increased. Conidia of the gldB disruption strain did not accumulate glycerol upon germination in glucose media with or without 1 M NaCl and germ tube emergence was significantly delayed in this strain in the presence of 1 M NaCl in comparison to the wild type. These data indicate that gldB is essential for osmotolerance in A. nidulans and that the pathways for glycerol biosynthesis under osmotic stress differ between yeast and filamentous fungi.
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