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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    Author Correction: The potential of future foods for sustainable and healthy diets
    Parodi, A. ; Leip, A. ; Boer, I.J.M. De; Slegers, P.M. ; Ziegler, F. ; Temme, E.H.M. ; Herrero, M. ; Tuomisto, H. ; Valin, H. ; Middelaar, C.E. Van; Loon, J.J.A. Van; Zanten, H.H.E. Van - \ 2019
    Nature Sustainability 2 (2019)4. - ISSN 2398-9629 - p. 342 - 347.

    In the version of this Article originally published, in Supplementary Table 7, the energy and land-use values for mealworms in Thevenot et al. were mistakenly swapped. The correct values are 65.39 MJ for energy use and 4.31 m 2 for land use. In the same table, the energy and land use values for black soldier fly in Salome et al. were incorrectly given as 0.14 MJ and 41.67 m 2 ; they should have read 7.248 MJ and 0.024 m 2 (respectively). Correcting these values has led to corresponding changes in Fig. 3, Supplementary Figs 2 and 4 and Supplementary Table 8. Additionally, in the panel of Fig. 3 that contains information about vitamin A, the land-use values of 593 for pork and 1914 for beef were incorrect, and should have been 666 and 3238, respectively.

    The potential of future foods for sustainable and healthy diets
    Parodi, A. ; Leip, A. ; Boer, I.J.M. De; Slegers, P.M. ; Ziegler, F. ; Temme, E.H.M. ; Herrero, M. ; Tuomisto, H. ; Valin, H. ; Middelaar, C.E. Van; Loon, J.J.A. Van; Zanten, H.H.E. Van - \ 2018
    Nature Sustainability 1 (2018). - ISSN 2398-9629 - p. 782 - 789.
    Altering diets is increasingly acknowledged as an important solution to feed the world’s growing population within the planetary boundaries. In our search for a planet-friendly diet, the main focus has been on eating more plant-source foods, and eating no or less animal-source foods, while the potential of future foods, such as insects, seaweed or cultured meat has been underexplored. Here we show that compared to current animal-source foods, future foods have major environmental benefits while safeguarding the intake of essential micronutrients. The complete array of essential nutrients in the mixture of future foods makes them good-quality alternatives for current animal-source foods compared to plant-source foods. Moreover, future foods are land-efficient alternatives for animal-source foods, and if produced with renewable energy, they also offer greenhouse gas benefits. Further research on nutrient bioavailability and digestibility, food safety, production costs and consumer acceptance will determine their role as main food sources in future diets.
    Host- and stage-dependent secretome of the arbuscular mycorrhizal fungus Rhizophagus irregularis
    Zeng, T. ; Limpens, E.H.M. - \ 2018
    Rhizophagus irregularis - GSE99655 - PRJNA389248
    Arbuscular mycorrhizal fungi arguably form the most successful and wide-spread endosymbiosis with plants. In general terms there is very little host-specificity in this interaction, indicating an extremely broad compatibility. However, host preferences as well as varying symbiotic efficiencies have been observed, the molecular basis of which is still largely unknown. Secreted proteins (SPs) may act as fungal effectors to control symbiotic efficiency in a host-dependent manner. Therefore, we studied whether AM fungi adjust their secretome in a host- and stage-dependent manner to contribute to their extremely wide host-range. We investigated the expression of SP encoding genes of R. irregularis DAOM197198 in three evolutionary distantly related plant species, Medicago truncatula (Medicago), Nicotiana benthamiana (Nicotiana) and Allium schoenoprasum (Chives). In addition we used laser microdissection in combination with RNAseq to study SP expression at different stages of the symbiotic interaction in Medicago. Our data indicate that the vast majority of 288 expressed SPs show equal expression levels in the interaction with all three host plants. In addition, a subset (~15%) of the SPs show significant differential expression depending on the host plant and/or environmental condition. This host-dependent expression appears to be controlled locally in the hyphal network in response to host metabolic cues. Overall, this study offers a comprehensive analysis of the R. irregularis secretome, which now offers a solid basis to direct functional studies on the role of fungal SPs in AM symbiosis.
    Formation of a symbiotic host-microbe interface: the role of SNARE-mediated regulation of exocytosis
    Huisman, Rik - \ 2018
    Wageningen University. Promotor(en): A.H.J. Bisseling, co-promotor(en): E.H.M. Limpens. - Wageningen : Wageningen University - ISBN 9789463323178 - 158

    At the heart of endosymbiosis microbes are hosted inside living cells in specialized membrane compartments that from a host-microbe interface, where nutrients and signal are efficiently exchanged. Such symbiotic interfaces include arbuscules produced by arbuscular mycorrhiza (AM) and organelle-like symbiosomes formed during the rhizobium-legume symbiosis. Also during pathogenic interactions, microbes such as biotrophic fungi and oomycetes are hosted in specialized membrane compartments called haustoria. The formation of such new membrane compartments requires a major reorganization of the host endomembrane system, with a special role for the targeting of secretory/exocytotic vesicles and their cargo to the newly forming interfaces. In this thesis, I studied how exocytotic membrane traffic is regulated to facilitate the formation and maintenance of a host-microbe interface. Therefore, I especially focussed on the role of SNARE (Soluble NSF Attachment Protein Receptor) proteins, as key components of the exocytotic machinery, in symbiotic interface formation.

    In Chapter 1, I introduce the different symbioses in which host-microbe interfaces are formed, and the role of the host-microbe interface in these symbioses. Further, I introduce the evolutionary relationship between the different symbioses: AM symbiosis is the most ancient endosymbiosis in plants, which provided the blueprint for different symbioses that evolved later; other symbiotic microbes including rhizobia co-opted the signalling program and adaptations to membrane trafficking required for arbuscule formation, to be hosted inside cells. Finally, I will introduce the symbiosis dedicated SNAREs as key regulators of exocytosis to form a host-microbe interface.

    In Chapter 2, we tested the long-standing hypothesis that pathogens make use of the AM symbiotic program to allow the formation of haustoria. To test this, we set up a pathosystem using the biotrophic oomycete Phytophthora palmivora that is able to form haustoria in Medicago truncatula root cells. Using M. truncatula mutants impaired in AM and rhizobium symbioses, we demonstrated that neither the common symbiotic signalling genes, nor symbiosis dedicated regulators of vesicle trafficking are required for haustorium formation. This showed that biotrophic pathogens like P. palmivora, do not hijack the symbiotic program to be accommodated inside plant cells.

    In Chapter 3, we identified the t-SNARE SYP132α as a key regulator of both arbuscule and symbiosome formation. During vesicle fusion, a vesicle SNARE (v-SNARE) on the vesicle forms a complex with a target membrane SNAREs (t-SNAREs) on the target membrane. Previous work in our lab identified specific exocytotic v-SNAREs required for arbuscule and symbiosome formation. We identified the t-SNARE counterpart SYP132, and demonstrated that in most dicot plants SYP132 is spliced into two spliceforms; SYP132α and SYP132β. Interestingly, alternative splicing of SYP132 leading to the dominant use of a SYP132α-specific last exon coincides with the accommodation of AM fungi in arbuscule forming root cortex cells and rhizobium bacteria in nodule cells. Using a spliceform-specific RNAi construct, we showed that SYP132α is specifically required for the formation of a stable host-microbe interface in both AM symbiosis and rhizobium symbiosis. Furthermore, we showed that during arbuscular collapse, the two spliceforms localize differently to healthy and degrading arbuscule branches. These results indicated that alternative splicing of SYP132 allows plants to replace a t-SNARE involved in traffic to the plasma membrane with a t-SNARE that is more stringent in its localization to functional arbuscules.

    The evolutionary expansion of SNAREs in plants has been hypothesized to have allowed the adaptation of exocytosis to different biological processes. In Chapter 4, we studied what makes the symbiotic SNAREs so special in comparison to their non-symbiotic family members, of which many are also expressed in arbuscule cells. We hypothesized that symbiotic SNAREs define a distinct secretory pathway, that ensures specificity of protein delivery to the host-microbe interface. We show that all tested SYP1 family proteins, and most of the non-symbiotic VAMP72 members, were able to complement the defect in arbuscule formation upon knock-down of their symbiotic counterparts when expressed at sufficient levels. This functional redundancy is in line with the ability of all tested v- and t-SNARE combinations to form SNARE complexes at the peri-arbuscular membrane. This showed that the symbiotic SNAREs do not selectively interact to define a distinct vesicle trafficking pathway, but that their essential role in arbuscule formation can be largely explained by their dominant expression level. Interestingly, the symbiotic t-SNARE SYP132α appeared to occur less in SNARE complexes with v-SNAREs compared to the non-symbiotic syntaxins in the arbuscule cells, suggesting a more strict regulation of symbiotic SNARE complexes at the interface.

    Since the alternative splicing of SYP132 does not affect the total transcript levels, we hypothesized that there must be a functional difference between SYP132α and –β, potentially leading to subtle phenotypes that may have gone undetected in the Agrobacterium rhizogenes mediated complementation approach applied in Chapter 4. In Chapter 5, we therefore generated and characterized a stable mutant line in which all SYP132 transcripts are constitutively spliced into the non-symbiotic SYP132β form. Although this mutant is normally colonized by AM fungi, with no effects on arbuscule morphology, it has a severely reduced biomass after mycorrhization. This hints to a yet unknown role for SYP132α to control arbuscule functionality, and offers an explanation for the evolutionary conservation of the SYP132 alternative splicing in dicot plants. Finally, using fluorescent timer fusions to both SYP132 isoforms, we showed that the difference in localization of the two proteins during arbuscular collapse is the result of a different (endocytic) turnover of the two spliceforms at the healthy/functional arbuscule branches, possibly due to a difference in interactions with VAMPs. Together, our data show that, although both SYP132 isoforms can mediate arbuscule formation, SYP132α is functionally different from SYP132β, which may reveal new aspects of the control of nutrient exchange.

    In Chapter 6, I discuss the data generated during my thesis research in relation to additional symbiosis dedicated regulators of exocytosis, as well as in relation to other biological processes that depend on specific secretory SNAREs. Following our conclusion that the symbiotic SNAREs do not mark a separate exocytosis pathway, but are functionally different from non-symbiotic SNAREs, I will speculate on the possible scenarios in which symbiosis dedicated SNAREs are specialized for host-microbe interface functionality.

    Development and evaluation of the Dutch Healthy Diet index 2015
    Looman, M. ; Feskens, E.J.M. ; Rijk, M.G. de; Meijboom, S. ; Briesbroek, S. ; Temme, E.H.M. ; Vries, J.H.M. de; Geelen, M.M.E.E. - \ 2017
    Public Health Nutrition 20 (2017)13. - ISSN 1368-9800 - p. 2289 - 2299.
    To update the Dutch Healthy Diet index, a measure of diet quality, to reflect adherence to the Dutch dietary guidelines 2015 and to evaluate against participants’ characteristics and nutrient intakes with the score based on 24 h recall (24 hR) data and FFQ data.
    The Dutch Healthy Diet index 2015 (DHD15-index) consists of fifteen components representing the fifteen food-based Dutch dietary guidelines of 2015. Per component the score ranges between 0 and 10, resulting in a total score between 0 (no adherence) and 150 (complete adherence).
    Wageningen area, the Netherlands, 2011–2013.
    Data of 885 men and women, aged 20–70 years, participating in the longitudinal NQplus study, who filled out two 24 hR and one FFQ, were used.
    Mean (sd) score of the DHD15-index was 68·7 (16·1) for men and 79·4 (16·0) for women. Significant inverse trends were found between the DHD15-index and BMI, smoking, and intakes of energy, total fat and saturated fat. Positive trends were seen across sex-specific quintiles of the DHD15-index score with energy-adjusted micronutrient intakes. Mean DHD15-index score of the FFQ data was 15·5 points higher compared with 24 hR data, with a correlation coefficient of 0·56 between the scores. Observed trends of the DHD15-index based on FFQ with participant characteristics, macronutrient and energy-adjusted micronutrient intakes were similar to those with the DHD15-index based on 24 hR.
    The DHD15-index score assesses adherence to the Dutch dietary guidelines 2015 and indicates diet quality. The DHD15-index score can be based on 24 hR data and on FFQ data.
    A robust supply chain planning framework for revenue management in the semiconductor industry
    Seitz, Alexander ; Ehm, Hans ; Akkerman, Renzo ; Osman, Sarah - \ 2016
    Journal of Revenue and Pricing Management 15 (2016)6. - ISSN 1476-6930 - p. 523 - 533.
    dynamic pricing - forecast accuracy - order management - semiconductor industry - supply chain contracts - supply chain planning

    High demand uncertainties, long production lead times, and short product life cycles cause high risks for supply chain planning in the semiconductor industry. These affect all industries producing goods containing semiconductors. We present a robust supply chain planning framework for revenue management that consists of stable and flexible solutions for demand steering and dynamic pricing, extending current industry practice in several aspects. We introduce the concept of availabilities and capabilities, as well as various planning processes and process enablers. Based on our framework, we also highlight directions for future research.

    Different responses of Caco-2 and MCF-7 cells to silver nanoparticles are based on highly similar mechanisms of action
    Zande, M. van der; Undas, A.K. ; Kramer, E.H.M. ; Monopoli, Marco P. ; Peters, R.J.B. ; Garry, David ; Antunes Fernandes, E.C. ; Hendriksen, P.J.M. ; Marvin, H.J.P. ; Peijnenburg, A.A.C.M. ; Bouwmeester, H. - \ 2016
    Homo sapiens - GSE84982 - PRJNA335824
    The mode of action of silver nanoparticles (AgNPs) is suggested to be exerted through both Ag+ and AgNP dependent mechanisms. Ingestion is one of the major NP exposure routes, and potential effects are often studied using Caco-2 cells, a well-established model for the gut epithelium. MCF-7 cells are epithelial breast cancer cells with extensive well-characterized toxicogenomics profiles. In the present study we aimed to gain a deeper understanding of the cellular molecular responses in Caco-2 and MCF-7 cells after AgNP exposure in order to evaluate whether epithelial cells derived from different tissues demonstrated similar responses. These insights could possibly reduce the size of cell panels for NP hazard identification screening purposes. AgNPs of 20, 30, 60, and 110 nm, and AgNO3 were exposed for 6h and 24h. AgNPs were shown to be taken up and dissolve intracellularly. Compared with MCF-7 cells, Caco-2 cells showed a higher sensitivity to AgNPs, slower gene expression kinetics, and absence of NP size-dependent responses. However, on a molecular level, no significant differences were observed between the two cell types. Transcriptomic analysis showed that Ag(NP) exposure caused (oxidative) stress responses, possibly leading to cell death in both cell lines. There was no indication for effects specifically induced by AgNPs. Responses to AgNPs appeared to be induced by silver ions released from the AgNPs. In conclusion, differences in mRNA responses to AgNPs between Caco-2 and MCF-7 cells were mainly related to timing and magnitude, but not to a different underlying mechanism.
    Silencing of six susceptibility genes results in potato late blight resistance
    Sun, Kaile ; Wolters, Anne-Marie A. ; Vossen, Jack H. ; Rouwet, Maarten E. ; Loonen, Annelies E.H.M. ; Jacobsen, Evert ; Visser, Richard G.F. ; Bai, Yuling - \ 2016
    Transgenic Research 25 (2016)5. - ISSN 0962-8819 - p. 731 - 742.
    Late blight - Potato - Resistance - RNAi - Susceptibility gene

    Phytophthora infestans, the causal agent of late blight, is a major threat to commercial potato production worldwide. Significant costs are required for crop protection to secure yield. Many dominant genes for resistance (R-genes) to potato late blight have been identified, and some of these R-genes have been applied in potato breeding. However, the P. infestans population rapidly accumulates new virulent strains that render R-genes ineffective. Here we introduce a new class of resistance which is based on the loss-of-function of a susceptibility gene (S-gene) encoding a product exploited by pathogens during infection and colonization. Impaired S-genes primarily result in recessive resistance traits in contrast to recognition-based resistance that is governed by dominant R-genes. In Arabidopsis thaliana, many S-genes have been detected in screens of mutant populations. In the present study, we selected 11 A. thalianaS-genes and silenced orthologous genes in the potato cultivar Desiree, which is highly susceptible to late blight. The silencing of five genes resulted in complete resistance to the P. infestans isolate Pic99189, and the silencing of a sixth S-gene resulted in reduced susceptibility. The application of S-genes to potato breeding for resistance to late blight is further discussed.

    Lipochitooligosaccharides modulate plant host immunity to enable endosymbioses
    Limpens, E.H.M. ; Zeijl, A.L. van; Geurts, R. - \ 2015
    Annual Review of Phytopathology 53 (2015). - ISSN 0066-4286 - p. 311 - 334.
    Symbiotic nitrogen-fixing rhizobium bacteria and arbuscular mycorrhizal fungi use lipochitooligosaccharide (LCO) signals to communicate with potential host plants. Upon a compatible match, an intimate relation is established during which the microsymbiont is allowed to enter root (-derived) cells. Plants perceive microbial LCO molecules by specific LysM-domain-containing receptor-like kinases. These do not only activate a common symbiosis signaling pathway that is shared in both symbioses but also modulate innate immune responses. Recent studies revealed that symbiotic LCO receptors are closely related to chitin innate immune receptors, and some of these receptors even function in symbiosis as well as immunity. This raises questions about how plants manage to translate structurally very similar microbial signals into different outputs. Here, we describe the current view on chitin and LCO perception in innate immunity and endosymbiosis and question how LCOs might modulate the immune system. Furthermore, we discuss what it takes to become an endosymbiont.
    Remodeling of the infection chamber before infection thread formation reveals a two-step mechanism for rhizobial entry into the host legume root hair
    Fournier, J. ; Teillet, A. ; Chabaud, M. ; Ivanov, S. ; Genre, A. ; Limpens, E.H.M. ; Carvalho-Niebel, F. de; Barker, D.G. - \ 2015
    Plant Physiology 167 (2015)4. - ISSN 0032-0889 - p. 1233 - 1242.
    In many legumes, root entry of symbiotic nitrogen-fixing rhizobia occurs via host-constructed tubular tip-growing structures known as infection threads (ITs). Here, we have used a confocal microscopy live-tissue imaging approach to investigate early stages of IT formation in Medicago truncatula root hairs (RHs) expressing fluorescent protein fusion reporters. This has revealed that ITs only initiate 10 to 20 h after the completion of RH curling, by which time major modifications have occurred within the so-called infection chamber, the site of bacterial entrapment. These include the accumulation of exocytosis (M. truncatula Vesicle-Associated Membrane Protein721e)- and cell wall (M. truncatula EARLY NODULIN11)-associated markers, concomitant with radial expansion of the chamber. Significantly, the infection-defective M. truncatula nodule inception-1 mutant is unable to create a functional infection chamber. This underlines the importance of the NIN-dependent phase of host cell wall remodeling that accompanies bacterial proliferation and precedes IT formation, and leads us to propose a two-step model for rhizobial infection initiation in legume RHs.
    Haustorium formation in Medicago truncatula roots infected by Phytophthora palmivora does not involve the common endosymbiotic program shared by AM fungi and rhizobia
    Huisman, R.H.J. ; Bouwmeester, K. ; Brattinga, M.A. ; Govers, F. ; Bisseling, A.H.J. ; Limpens, E.H.M. - \ 2015
    Molecular Plant-Microbe Interactions 28 (2015)12. - ISSN 0894-0282 - p. 1271 - 1280.
    In biotrophic plant-microbe interactions, microbes infect living plant cells where they are hosted in a novel membrane compartment; the host-microbe interface. To create a host-microbe interface, arbuscular mycorrhizal (AM) fungi and rhizobia make use of the same endosymbiotic program. It is a long-standing hypothesis that pathogens make use of plant proteins that are dedicated to mutualistic symbiosis to infect plants and form haustoria. In this report, we developed a Phytophthora palmivora pathosystem to study haustorium formation in Medicago truncatula (Medicago) roots. We show that P. palmivora does not require host genes that are essential for symbiotic infection and host-microbe interface formation to infect Medicago roots and form haustoria. Based on these findings, we conclude that P. palmivora does not hijack the ancient intracellular accommodation program used by symbiotic microbes to form a biotrophic host-microbe interface.
    In vitro gastrointestinal digestion increases the translocation of polystryrene nanoparticles in an in vitro intestinal co-culture model
    Walczak, A.P. ; Kramer, E.H.M. ; Hendriksen, P.J.M. ; Helsdingen, J.R. ; Zande, M. van der; Rietjens, I.M.C.M. ; Bouwmeester, H. - \ 2015
    Nanotoxicology 9 (2015)7. - ISSN 1743-5390 - p. 886 - 894.
    The conditions of the gastrointestinal tract may change the physicochemical properties of nanoparticles (NPs) and therewith the bioavailability of orally taken NPs. Therefore, we assessed the impact of in vitro gastrointestinal digestion on the protein corona of polystyrene NPs (PS-NPs) and their subsequent translocation across an in vitro intestinal barrier. A co-culture of intestinal Caco-2 and HT29-MTX cells was exposed to 50¿nm PS-NPs of different charges (positive and negative) in two forms: pristine and digested in an in vitro gastrointestinal digestion model. In vitro digestion significantly increased the translocation of all, except the “neutral”, PS-NPs. Upon in vitro digestion, translocation was 4-fold higher for positively charged NPs and 80- and 1.7-fold higher for two types of negatively charged NPs. Digestion significantly reduced the amount of protein in the corona of three out of four types of NPs. This reduction of proteins was 4.8-fold for “neutral”, 3.5-fold for positively charged and 1.8-fold for one type of negatively charged PS-NPs. In vitro digestion also affected the composition of the protein corona of PS-NPs by decreasing the presence of higher molecular weight proteins and shifting the protein content of the corona to low molecular weight proteins. These findings are the first to report that in vitro gastrointestinal digestion significantly affects the protein corona and significantly increases the in vitro translocation of differently charged PS-NPs. These findings stress the importance of including the in vitro digestion in future in vitro intestinal translocation screening studies for risk assessment of orally taken NPs.
    Reduced-Sodium Lunches Are Well-Accepted by Uninformed Consumers Over a 3-Week Period and Result in Decreased Daily Dietary Sodium Sodium Intakes: A Randomized Controlled Trial
    Janssen, A.M. ; Kremer, S. ; Stipriaan, W.L. van; Noort, M.W.J. ; Vries, J.H.M. de; Temme, E.H.M. - \ 2015
    Journal of the Academy of Nutrition and Dietetics 115 (2015)10. - ISSN 2212-2672 - p. 1614 - 1625.
    Background Processed foods are major contributors to excessive sodium intake in Western populations. We investigated the effect of food reformulation on daily dietary sodium intake. Objective To determine whether uninformed consumers accept reduced-sodium lunches and to determine the effect of consuming reduced-sodium lunches on 24-hour urinary sodium excretion. Design A single-blind randomized controlled pretest-posttest design with two parallel treatment groups was used. Participants/setting Participants chose foods in an experimental real-life canteen setting at the Restaurant of the Future in Wageningen, the Netherlands, from May 16 until July 1, 2011. Intervention After a run-in period with regular foods for both groups, the intervention group (n=36) consumed foods with 29% to 61% sodium reduction (some were partially flavor compensated). The control group (n=38) continued consuming regular foods. Main outcome measures Outcomes for assessment of acceptance were the amount of foods consumed, energy and sodium intake, remembered food liking, and intensity of sensory aspects. Influence on daily dietary sodium intake was assessed by 24-hour urinary sodium excretion. Statistical analyses performed Between and within-subject comparisons were assessed by analysis of covariance. Results Energy intake and amount consumed of each food category per lunch remained similar for both groups. Compared with the control group, the intervention group’s sodium intake per lunch was significantly reduced by –1,093 mg (adjusted difference) (95% CI –1,285 to –901), equivalent to 43 mmol sodium. Remembered food liking, taste intensity, and saltiness were scored similarly for almost all of the reduced-sodium foods compared with the regular foods. After consuming reduced-sodium lunches, compared with the control group, intervention participants’ 24-hour urinary sodium excretion was significantly lower by –40 mEq (adjusted difference) (95% CI –63 to –16) than after consuming regular lunches, and this reflects a decreased daily sodium intake of 1 g. Conclusions Comparing the two treatment groups, consumption of reduced-sodium foods over a 3-week period was well accepted by the uninformed participants in an experimental real-life canteen setting. The reduced-sodium foods did not trigger compensation behavior during the remainder of the day in the intervention group compared with the control group, as reflected by 24-hour urinary sodium excretion. Therefore, offering reduced-sodium foods without explicitly informing consumers of the sodium reduction can contribute to daily sodium intake reduction.
    Translocation of differently sized and charged polystyrene nanoparticles in in vitro intestinal cell models of increasing complexity
    Walczak, A.P. ; Kramer, E.H.M. ; Hendriksen, P.J.M. ; Tromp, P. ; Helsper, J.P.F.G. ; Zande, M. van der; Rietjens, I.M.C.M. ; Bouwmeester, H. - \ 2015
    Nanotoxicology 9 (2015)4. - ISSN 1743-5390 - p. 453 - 461.
    Intestinal translocation is a key factor for determining bioavailability of nanoparticles (NPs) after oral uptake. Therefore, we evaluated three in vitro intestinal cell models of increasing complexity which might affect the translocation of NPs: a mono-culture (Caco-2 cells), a co-culture with mucus secreting HT29-MTX cells and a tri-culture with M-cells. Cell models were exposed to well characterized differently sized (50 and 100¿nm) and charged (neutral, positively and negatively) polystyrene NPs. In addition, two types of negatively charged NPs with different surface chemistries were used. Size strongly affected the translocation of NPs, ranging up to 7.8% for the 50¿nm NPs and 0.8% for the 100¿nm NPs. Surface charge of NPs affected the translocation, however, surface chemistry seems more important, as the two types of negatively charged 50¿nm NPs had an over 30-fold difference in translocation. Compared with the Caco-2 mono-culture, presence of mucus significantly reduced the translocation of neutral 50¿nm NPs, but significantly increased the translocation of one type of negatively charged NPs. Incorporation of M-cells shifted the translocation rates for both NPs closer to those in the mono-culture model. The relative pattern of NP translocation in all three models was similar, but the absolute amounts of translocated NPs differed per model. We conclude that for comparing the relative translocation of different NPs, using one intestinal model is sufficient. To choose the most representative model for risk assessment, in vivo experiments are now needed to determine the in vivo translocation rates of the used NPs
    Nod factor receptors form heteromeric complexes and are essential for intracellular infection in Medicago nodules
    Moling, S. ; Pietraszewska-Bogiel, A. ; Postma, M. ; Fedorova, E.E. ; Hink, M.A. ; Limpens, E.H.M. ; Gadella, T.W.J. ; Bisseling, T. - \ 2014
    The Plant Cell 26 (2014)10. - ISSN 1040-4651 - p. 4188 - 4199.
    rhizobium-leguminosarum - n-2-fixing symbiosomes - root-nodules - kinase - truncatula - arabidopsis - lyk3 - phosphorylation - perception - nodulation
    Rhizobial Nod factors are the key signaling molecules in the legume-rhizobium nodule symbiosis. In this study, the role of the Nod factor receptors NOD FACTOR PERCEPTION (NFP) and LYSIN MOTIF RECEPTOR-LIKE KINASE3 (LYK3) in establishing the symbiotic interface in root nodules was investigated. It was found that inside Medicago truncatula nodules, NFP and LYK3 localize at the cell periphery in a narrow zone of about two cell layers at the nodule apex. This restricted accumulation is narrower than the region of promoter activity/mRNA accumulation and might serve to prevent the induction of defense-like responses and/or to restrict the rhizobium release to precise cell layers. The distal cell layer where the receptors accumulate at the cell periphery is part of the meristem, and the proximal layer is part of the infection zone. In these layers, the receptors can most likely perceive the bacterial Nod factors to regulate the formation of symbiotic interface. Furthermore, our Förster resonance energy transfer-fluorescence lifetime imaging microscopy analysis indicates that NFP and LYK3 form heteromeric complexes at the cell periphery in M. truncatula nodules.
    Plant-driven genome selection of arbuscular mycorrhizal fungi
    Limpens, E.H.M. ; Geurts, R. - \ 2014
    Molecular Plant Pathology 15 (2014)6. - ISSN 1464-6722 - p. 531 - 534.
    symbiosis
    Bioaccessibility of vitamin A, vitamin C and folic acid from dietary supplements fortified food and infant formula
    Brandon, E.F.A. ; Bakker, M.I. ; Kramer, E.H.M. ; Bouwmeester, H. ; Zuidema, T. ; Alewijn, M. - \ 2014
    International Journal of Food Sciences and Nutrition 65 (2014)4. - ISSN 0963-7486 - p. 426 - 435.
    in-vitro digestion - beta-carotene - gastrointestinal model - bioavailability - nutrition
    In the Netherlands, vitamin intake occurs mainly via food and for some vitamins also via fortified food. In addition, some people take dietary supplements. Information on the bioavailability of vitamins is important for a good estimation of the actual exposure to vitamins. Furthermore, for a reliable intake estimation, it is important to know the accurateness of the claimed vitamin concentration on the product label. In the current study, the amount of vitamin A, vitamin C, and folic acid in different products and their maximum bioavailability (bioaccessibility) were investigated. In about half of the products, the amount of vitamins significantly deviated from the declared amounts. The vitamin bioaccessibility ranged from
    Sub-chronic toxicity study in rats orally exposed to nanostructured silica
    Zande, M. van der; Vandebriel, R.J. ; Groot, M.J. ; Kramer, E.H.M. ; Herrera Riviera, Z.E. ; Rasmussen, K. ; Ossenkoppele, J.S. ; Tromp, P. ; Gremmer, E.R. ; Peters, R.J.B. ; Hendriksen, P.J. ; Marvin, H.J.P. ; Hoogenboom, L.A.P. ; Peijnenburg, A.A.C.M. ; Bouwmeester, H. - \ 2014
    Particle and Fibre Toxicology 11 (2014). - ISSN 1743-8977
    in-vivo biodistribution - expression profiles - liver fibrosis - nanoparticles - absorption - elimination - injection - foods - acid - size
    Synthetic Amorphous Silica (SAS) is commonly used in food and drugs. Recently, a consumer intake of silica from food was estimated at 9.4 mg/kg bw/day, of which 1.8 mg/kg bw/day was estimated to be in the nano-size range. Food products containing SAS have been shown to contain silica in the nanometer size range (i.e. 5 – 200 nm) up to 43% of the total silica content. Concerns have been raised about the possible adverse effects of chronic exposure to nanostructured silica.
    CYCLOPS: a new vision on rhizobium-induced nodule organogenesis : Preview
    Limpens, E.H.M. ; Bisseling, T. - \ 2014
    Cell Host & Microbe 15 (2014)2. - ISSN 1931-3128 - p. 127 - 129.
    medicago-truncatula - infection
    The accommodation of nitrogen-fixing rhizobium bacteria inside plant cells requires reprogramming of root cortex cells by rhizobial signals. In this issue of Cell Host & Microbe, Singh et al. (2014) reveal that CYCLOPS, representing a novel class of transcription factors, links rhizobium-induced calcium signaling to reprogramming of root cortex cells.
    Single nucleus genome sequencing reveals high similarity among nuclei of an endomycorrhizal fungus
    Lin, K. ; Limpens, E.H.M. ; Zhang, Z. ; Ivanov, S. ; Saunders, D.G.O. ; Mu, D. ; Pang, E. ; Cao, H. ; Cha, H. ; Lin, T. ; Zhou, Q. ; Shang, Y. ; Li, Y. ; Sharma, T.C. ; Velzen, R. van; Ruijter, N.C.A. de; Aanen, D.K. ; Win, J. ; Kamoun, S. ; Bisseling, T. ; Geurts, R. ; Huang, S.W. - \ 2014
    Plos Genetics 10 (2014)1. - ISSN 1553-7404 - 13 p.
    arbuscular mycorrhizal fungi - pathogen phytophthora-infestans - glomus-intraradices - sexual reproduction - protein families - cdna sequences - kingdom fungi - gene - identification - efficient
    Nuclei of arbuscular endomycorrhizal fungi have been described as highly diverse due to their asexual nature and absence of a single cell stage with only one nucleus. This has raised fundamental questions concerning speciation, selection and transmission of the genetic make-up to next generations. Although this concept has become textbook knowledge, it is only based on studying a few loci, including 45S rDNA. To provide a more comprehensive insight into the genetic makeup of arbuscular endomycorrhizal fungi, we applied de novo genome sequencing of individual nuclei of Rhizophagus irregularis. This revealed a surprisingly low level of polymorphism between nuclei. In contrast, within a nucleus, the 45S rDNA repeat unit turned out to be highly diverged. This finding demystifies a long-lasting hypothesis on the complex genetic makeup of arbuscular endomycorrhizal fungi. Subsequent genome assembly resulted in the first draft reference genome sequence of an arbuscular endomycorrhizal fungus. Its length is 141 Mbps, representing over 27,000 protein-coding gene models. We used the genomic sequence to reinvestigate the phylogenetic relationships of Rhizophagus irregularis with other fungal phyla. This unambiguously demonstrated that Glomeromycota are more closely related to Mucoromycotina than to its postulated sister Dikarya.
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