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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    Rain downpours affect survival and development of insect herbivores: the specter of climate change?
    Chen, Cong ; Harvey, Jeffrey A. ; Biere, Arjen ; Gols, Rieta - \ 2019
    Ecology 100 (2019)11. - ISSN 0012-9658
    climate change - development - global warming - glucosinolates - insect herbivores - phytochemistry - plant–insect interactions - rain - secondary plant metabolites

    Changes in the frequency, duration, and intensity of rainfall events are among the abiotic effects predicted under anthropogenic global warming. Heavy downpours may profoundly affect the development and survival of small organisms such as insects. Here, we examined direct (physically on the insects) and indirect (plant-mediated) effects of simulated downpours on the performance of caterpillars of two lepidopteran herbivores (Plutella xylostella and Pieris brassicae) feeding on black mustard (Brassica nigra) plants. Host plants were exposed to different rainfall regimes both before and while caterpillars were feeding on the plants in an attempt to separate direct and indirect (plant-mediated) effects of rainfall on insect survival and development. In two independent experiments, downpours were simulated as a single long (20 min) or as three short (5 min) daily events. Downpours had a strong negative direct effect on the survival of P. xylostella, but not on that of P. brassicae. Direct effects of downpours consistently increased development time of both herbivore species, whereas effects on body mass depended on herbivore species and downpour frequency. Caterpillar disturbance by rain and recorded microclimatic cooling by 5°C may explain extended immature development. Indirect, plant-mediated effects of downpours on the herbivores were generally small, despite the fact that sugar concentrations were reduced and herbivore induction of secondary metabolites (glucosinolates) was enhanced in plants exposed to rain. Changes in the frequency of precipitation events due to climate change may impact the survival and development of insect herbivores differentially. Broader effects of downpours on insects and other arthropods up the food chain could seriously impair and disrupt trophic interactions, ultimately destabilizing communities.

    Live cell imaging of meiosis in Arabidopsis thaliana
    Prusicki, Maria A. ; Keizer, Emma M. ; Rosmalen, Rik P. van; Komaki, Shinichiro ; Seifert, Felix ; Müller, Katja ; Wijnker, Erik ; Fleck, Christian ; Schnittger, Arp - \ 2019
    eLife 8 (2019). - ISSN 2050-084X
    A. thaliana - cell biology - cyclin - development - meiosis - phragmoplast - plant biology - reproduction - spindle

    To follow the dynamics of meiosis in the model plant Arabidopsis, we have established a live cell imaging setup to observe male meiocytes. Our method is based on the concomitant visualization of microtubules (MTs) and a meiotic cohesin subunit that allows following five cellular parameters: cell shape, MT array, nucleus position, nucleolus position, and chromatin condensation. We find that the states of these parameters are not randomly associated and identify 11 cellular states, referred to as landmarks, which occur much more frequently than closely related ones, indicating that they are convergence points during meiotic progression. As a first application of our system, we revisited a previously identified mutant in the meiotic A-type cyclin TARDY ASYNCHRONOUS MEIOSIS (TAM). Our imaging system enabled us to reveal both qualitatively and quantitatively altered landmarks in tam, foremost the formation of previously not recognized ectopic spindle- or phragmoplast-like structures that arise without attachment to chromosomes.

    The Preterm Gut Microbiota: An Inconspicuous Challenge in Nutritional Neonatal Care
    Henderickx, Jannie G.E. ; Zwittink, Romy D. ; Lingen, Richard A. van; Knol, Jan ; Belzer, Clara - \ 2019
    Frontiers in Cellular and Infection Microbiology 9 (2019). - ISSN 2235-2988 - 1 p.
    development - gastrointestinal tract - growth - gut microbiota - health - immune system - preterm - very low birth weight

    The nutritional requirements of preterm infants are unique and challenging to meet in neonatal care, yet crucial for their growth, development and health. Normally, the gut microbiota has distinct metabolic capacities, making their role in metabolism of dietary components indispensable. In preterm infants, variation in microbiota composition is introduced while facing a unique set of environmental conditions. However, the effect of such variation on the microbiota's metabolic capacity and on the preterm infant's growth and development remains unresolved. In this review, we will provide a holistic overview on the development of the preterm gut microbiota and the unique environmental conditions contributing to this, in addition to maturation of the gastrointestinal tract and immune system in preterm infants. The role of prematurity, as well as the role of human milk, in the developmental processes is emphasized. Current research stresses the early life gut microbiota as cornerstone for simultaneous development of the gastrointestinal tract and immune system. Besides that, literature provides clues that prematurity affects growth and development. As such, this review is concluded with our hypothesis that prematurity of the gut microbiota may be an inconspicuous clinical challenge in achieving optimal feeding besides traditional challenges, such as preterm breast milk composition, high nutritional requirements and immaturity of the gastrointestinal tract and immune system. A better understanding of the metabolic capacity of the gut microbiota and its impact on gut and immune maturation in preterm infants could complement current feeding regimens in future neonatal care and thereby facilitate growth, development and health in preterm infants.

    Data from: Responses of insect herbivores and their food plants to wind exposure and the importance of predation risk
    Chen, C. ; Biere, Arjen ; Gols, R. ; Halfwerk, Wouter ; Oers, C.H.J. ; Harvey, J.A. - \ 2018
    Wageningen University and Research
    development - abiotic factors - plant-herbivore interactions - predator - plutella xylostella - Pieris brassicae - Parus major
    1. Wind is an important abiotic factor that influences an array of biological processes, but it is rarely considered in studies on plant-herbivore interactions. 2. Here, we tested whether wind exposure could directly or indirectly affect the performance of two insect herbivores, Plutella xylostella and Pieris brassicae, feeding on Brassica nigra plants. 3. In a greenhouse study using a factorial design, B. nigra plants were exposed to different wind regimes generated by fans before and after caterpillars were introduced on plants in an attempt to separate the effects of direct and indirect wind exposure on herbivores. 4. Wind exposure delayed flowering, decreased plant height and increased leaf concentrations of amino acids and glucosinolates. 5. Plant-mediated effects of wind on herbivores, i.e., effects of exposure of plants to wind prior to herbivore feeding, were generally small. However, development time of both herbivores was extended and adult body mass of P. xylostella was reduced when they were directly exposed to wind. By contrast, wind-exposed adult P. brassicae butterflies were significantly larger, revealing a trade-off between development time and adult size. 6. Based on these results, we conducted a behavioral experiment to study preference by an avian predator, the Great Tit (Parus major) for last instar P. brassicae caterpillars on plants that were exposed to either control (no wind) or wind (fan-exposed) treatments. Tits captured significantly more caterpillars on still than on wind-exposed plants. 7. Our results suggest that P. brassicae caterpillars are able to perceive the abiotic environment and to trade off the costs of extended development time against the benefits of increased size depending on the perceived risk of predation mediated by wind exposure. Such adaptive phenotypic plasticity in insects has not yet been described in response to wind exposure.
    Data from: The early-life environment of a pig shapes the phenotypes of its social partners in adulthood
    Canario, L. ; Lundeheim, N. ; Bijma, P. - \ 2017
    development - early-life environment - indirect genetic effect - kin selection - social partners - Sus scrofa
    Social interactions among individuals are abundant, both in natural and domestic populations, and may affect phenotypes of individuals. Recent research has demonstrated that the social effect of an individual on the phenotype of its social partners may have a genetic component, known as an Indirect Genetic Effect (IGE). Little is known, however, of non-genetic factors underlying such social effects. Early life environments often have large effects on phenotypes of the individuals themselves later in life. Offspring development in many mammalian species, for example, depends on interactions with the mother and siblings. In domestic pigs, individuals sharing the same juvenile environment develop similar body weight later in life. We, therefore, hypothesized that offspring originating from the same early-life environment also develop common social skills, which generate Early-Life Social Effects (ELSE) that affect the phenotypes of their social partners later in life. We, therefore, quantified IGEs and ELSEs on growth in domestic pigs. Results show that individuals from the same early-life environment express similar social effects on the growth of their social partners, and that such ELSE shape the growth rate of social partners more than IGE. Thus, the social skills that individuals develop in early-life have a long-lasting impact on the phenotypes of social partners. Early-life and genetic social effects were independent of the corresponding direct effects of offspring on their own growth, indicating that individuals may enhance the growth of their social partners without a personal cost. Our findings also illustrate how research devoted to quantifying IGEs may miss non-genetic and potentially confounded social mechanisms, which may bias the estimates of IGEs.
    Authenticity and the Contradictions of the “Ecotourism Script” : Global Marketing and Local Politics in Ghana
    Büscher, Bram ; Bremer, Renée van den; Fletcher, Robert ; Koot, Stasja - \ 2017
    Critical Arts 31 (2017)4. - ISSN 0256-0046 - p. 37 - 52.
    authenticity - development - ecotourism - Ghana - marketing - politics
    Tourism in Ghana has been developing rapidly over the last decade. By marketing over a dozen “community ecotourism” sites, particularly around monkey and forest sanctuaries, Ghana hopes to attract travellers to spend money in the country and so aid local development and protect natural resources. This paper analyses this trend, outlining several contradictions in the country’s national branding of “authenticity” in ecotourism and how this takes local shape in the case of the Tafi-Atome monkey sanctuary in Eastern Ghana. We propose that actors on different levels in Ghana appear to market and brand ecotourism according to a “script” that directs and influences local ecotourism practices in ways that obscure these contradictions and thereby enable continuation of and belief in the script. We conclude that this “ecotourism script” is central to the promotion and implementation of ecotourism in general, and needed to maintain the belief that the activity is an important conservation and development panacea.
    Functional analyses of plant-specific histone deacetylases : Their role in root development, stress responses and symbiotic interactions
    Li, Huchen - \ 2017
    Wageningen University. Promotor(en): T. Bisseling, co-promotor(en): O. Kulikova. - Wageningen : Wageningen University - ISBN 9789463436816 - 188
    plants - histones - enzymes - roots - development - symbiosis - gene expression - molecular biology - root nodules - mycorrhizas - planten - histonen - enzymen - wortels - ontwikkeling - symbiose - genexpressie - moleculaire biologie - wortelknolletjes - mycorrhizae

    Plants have a sessile lifestyle. To ensure survival, they develop a potential to respond to environmental cues to set up an adaptive growth and development. This adaptation involves transcriptional reprogramming of the genome through chromatin-based mechanisms relying on the dynamic interplay of transcription factors (TFs), post-translational modification of histones, the deposition of histone variants, DNA methylation, and nucleosome remodeling. This thesis is focused on a role of one group of histone post-translational modifiers, plant-specific histone deacetylases (HDTs), in plant development under control condition and variable stresses/symbiotic interactions.

    It is well known that HDTs are involved in plant responses to environmental stresses. However, whether they play a role in regulating plant growth and development is elusive. In this thesis it is shown that Arabidopsis thaliana AtHDT1/2 regulate the cell fate switch from division to expansion in the Arabidopsis root. Knock-down of AtHDT1/2 (hdt1,2i) causes that this switch occurs earlier and results in less cells in the root meristem. This process slows down root growth. One target of AtHDT1/2, AtGA2ox2, is identified here. Its overexpression displays the same root phenotype as hdt1/2i , and its knock-out partially rescues hdt1,2i root meristem phenotype. AtGA2ox2 inactivates gibberellin (GA4) whose application increases root meristem cell number in WT, but not in hdt1,2i. Based on these data, we conclude that AtHDT1/2 repress the transcription of AtGA2ox2, and likely fine-tunes GA homeostasis to regulate the switch from cell division to expansion in root tips.

    HDTs respond to salt stress in Arabidopsis seedlings. Halotropism is a novel reported tropism allowing roots to avoid a saline environment. Whether the AtHDT1/2-AtGA2ox2 module is operational in halotropism is studied here. We show that hdt1,2i mutants respond more severe in halotropism. AtHDT1/2, as well as AtGA2ox2 display asymmetric localization patterns in halotropism with AtHDT1/2 reduced and AtGA2ox2 induced at high salt side of root tips. Our data indicate that their asymmetric patterns likely results in less GA at high salt side of root tips and this is required for halotropism establishment. In line with this, both constitutive expression of AtHDT2 and exogenous GA application reduce halotropic response. A reduction of GA in root tips causes an earlier switch from cell division to expansion. We discuss that this earlier switch enables roots rapidly to bend away from saline environment.

    It has been shown that HDTs play a role under biotic stress in rice and tobacco leaves. We demonstrate that they are also involved in response to biotic stress in Arabidopsis leaves. Arabidopsis hdt2 mutants are more susceptible to virulent Pseudomonas syringae pv. tomato PstDC3000, whereas AtHDT2 overexpression mutants are more resistant. In addition, we detected a translocation of AtHDT2 from nucleolus to nucleoplasm after the perception of flagellin22 in Arabidopsis leaf cells. This translocation is not observed under abiotic stress. A mechanism controlling this translocation is identified. AtMPK3 is activated under biotic stress, it interacts with and phosphorylates AtHDT2. This leads to the accumulation of AtHDT2 in nucleoplasm where it contributes to the repression of defense genes.

    During the interaction with symbiotic microorganisms, plants could develop a symbiotic organ/structure. For example, legumes of which Medicago truncatula is a model, can form root nodules or arbuscules by interacting with rhizobia or arbuscular mycorrhiza.

    We show that nodule-specific knock-down of MtHDT1/2/3 (MtHDTs RNAi) blocks nodule primordia development and affects the function of nodule meristem. This is consistent with their roles in controlling cell division during root development and suggests that the function of nodule and root meristems is closely related. However, MtHDT2 gains a new sub-nuclear localization pattern in nodule meristem by using a not yet known mechanism, different from that in root meristem. This suggests that these two meristems have different transcriptional landscapes. In the nodule infection zone MtHDTs are also expressed and in MtHDTs RNAi the intracellular release of rhizobia is markedly reduced. Expression of MtHMGR1 and its paralogs, encoding 3-hydroxy-3-methylglutaryl-coenzyme A reductases are down-regulated in MtHDTs RNAi. It has been shown MtHMGR1 interacts with MtDMI2, a component of Nod factor signalling pathway, to control rhizobial infection. Knock-down of MtHMGR1/MtDMI2, as well as inhibiting MtHMGRs enzymatic activity blocks nodule primordia development and rhizobial infection in nodule primordia/mature nodules. This phenotype partially resembles MtHDTs RNAi phenotype. We discuss that MtHDTs regulate expression of MtHMGRs and in this way affect Nod factor signalling and control nodule development.

    Similar to nodule symbiosis, during arbuscular mycorrhizal symbiosis cells in the cortex are also intracellularly infected. We show that MtHDT2 is also induced in these arbuscule containing cells. Knock-down of MtHDT2 (MtHDT2i) significantly reduces the intracellular infection of the hyphae on the mycorrhized root segments, indicating that MtHDT2 control mycorrhizal intracellular infection. We discuss whether MtHDTs can regulate mycorrhizal/rhizobial infection in a similar way.

    The data obtained in this thesis and the published information related to these subjects are discussed at the end. HDTs are key players in plant responses to environmental cues, whereas they respond to abiotic factors and biotic factors differently. They are also key regulators of plant growth and development that is clearly demonstrated in this thesis on examples of root and nodule development. I also propose a role of AtHDT1/2 in response to salt signal to fine-tune the switch from cell division to expansion in root tips during halotropism.

    What’s cooking? Unverified assumptions, overlooking of local needs and pro-solution biases in the solar cooking literature
    Iessa, L. ; Vries, Y.A. de; Swinkels, C.E. ; Smits, M. ; Butijn, C.A.A. - \ 2017
    Energy Research & Social Science 28 (2017). - ISSN 2214-6296 - p. 98 - 108.
    solar cooking - review - development - practices
    Solar cookers have been tested and studied in various settings, but despite their envisioned benefits – reduction of deforestation, economic benefits, improved health, and empowerment of women – results have been modest at best. This article performs a critical review of the literature on solar cooking (SC), to scrutinise the assumptions and methodological choices that may explain this conundrum. The literature review yielded 32 articles on solar cookers in Sub-Saharan Africa, where most SC projects can be found. Four recurrent types of issues stand out: local needs are often not sufficiently considered, existing cooking and fuelwood practices are seen as obstacles, many articles show a prosolution bias and there is a lack of methodologically sound impact studies. To overcome these issues, practice theory – which analyses the practice of cooking from the logic of the practice, rather than from an external point of view – is proposed to guide and focus future SC projects and studies. Furthermore, ethnographical methods can provide new and grounded evidence and allow for a stronger focus on local needs. These approaches can provide a fruitful evidence base to analyse the role of solar-cooking in achieving sustainable and long-term development benefits in the Global South.
    A maternal Western diet during gestation and lactation modifies offspring’s microbiota activity, blood lipid levels, cognitive responses, and hippocampal neurogenesis in Yucatan pigs
    Val-Laillet, David ; Besson, M. ; Guérin, S. ; Coquery, N. ; Randuineau, G. ; Kanzari, A. ; Quesnel, H. ; Bonhomme, N. ; Bolhuis, J.E. ; Kemp, B. ; Blat, S. ; Huërou-Luron, I. Le; Clouard, C.M. - \ 2017
    FASEB Journal 31 (2017)5. - ISSN 0892-6638 - p. 2037 - 2049.
    early nutrition - development - eating behavior - metabolism - brain
    A suboptimal early nutritional environment (i.e., excess of energy, sugar, and fat intake) can increase susceptibility to diseases and neurocognitive disorders. The purpose of this study was to investigate in nonobese Yucatan minipigs (Sus scrofa) the impact of maternal diet [standard (SD) vs. Western (WD) diet] during gestation and 25 d of lactation on milk composition, blood metabolism, and microbiota activity of sows (n = 17) and their piglets (n = 65), and on spatial cognition (n = 51), hippocampal plasticity (n = 17), and food preferences/motivation (n = 51) in the progeny. Milk dry matter and lipid content, as well as plasma total cholesterol and free fatty acid (FFA) concentrations (P < 0.05) were higher in WD than in SD sows. Microbiota activity decreased in both WD sows and 100-d-old piglets (P < 0.05 or P < 0.10, depending on short-chain FAs [SCFAs]). At weaning [postnatal day (PND) 25], WD piglets had increased blood triglyceride and FFA levels (P < 0.01). Both SD and WD piglets consumed more of a known SD than an unknown high-fat/-sucrose (HFS) diet (P < 0.0001), but were quicker to obtain HFS rewards compared with SD rewards (P < 0.01). WD piglets had higher working memory (P = 0.015) and reference memory (P < 0.001) scores, which may reflect better cognitive abilities in the task context and a higher motivation for the food rewards. WD piglets had a smaller hippocampal granular cell layer (P = 0.03) and decreased neurogenesis (P < 0.005), but increased cell proliferation (P < 0.001). A maternal WD during gestation and lactation, even in the absence of obesity, has significant consequences for piglets’ blood lipid levels, microbiota activity, gut–brain axis, and neurocognitive abilities after weaning.—Val-Laillet, D., Besson, M., Guérin, S., Coquery, N., Randuineau, G., Kanzari, A., Quesnel, H., Bonhomme, N., Bolhuis, J. E., Kemp, B., Blat, S., Le Huërou-Luron, I., Clouard, C. A maternal Western diet during gestation and lactation modifies offspring’s microbiota activity, blood lipid levels, cognitive responses, and hippocampal neurogenesis in Yucatan pigs.
    Data from: Plant quantity affects development and survival of a gregarious insect herbivore and its endoparasitoid wasp
    Fei, Minghui ; Gols, R. ; Zhu, F. ; Harvey, Jeffrey A. - \ 2016
    Wageningen University & Research
    development - group-living - herbivore - mortality - parasitiod - phenology - starvation - survival
    Data for the paper of plant quantity represents a greater constraint than quality for a gregarious insect herbivore and its endoparasitoid wasp
    Energy status and ovarian follicular development
    Meng, Li - \ 2016
    Wageningen University. Promotor(en): Jaap Keijer; Katja Teerds. - Wageningen : Wageningen University - ISBN 9789462579170 - 144
    ovarian development - energy - follicles - reproduction - atresia - development - ovaries - ovariumontwikkeling - energie - follikels - voortplanting - atresie - ontwikkeling - ovaria

    Female reproduction is tightly linked to body energy status and it has become increasingly clear that disturbed energy metabolism can negatively affect reproductive performance. Nevertheless, the way how a disturbed energy status affects ovarian follicular reserve as well as follicular recruitment and growth is little investigated and not fully elucidated. Therefore, the overall goal of this thesis was to investigate the effects of an altered metabolism, and particularly an altered energy status, on ovarian follicular development. To achieve this goal, the first aim was to establish the role of autophagy in follicular degeneration under normal physiological conditions, with focus on preantral and antral follicles; The second aim was to elucidate the effects of a diet-induced reduction in thyroid hormone concentrations, affecting whole body metabolism, on ovarian follicular development; The third aim was to investigate the effect of an increased nutrient flux towards skeletal muscle on ovarian follicular development and the possible underlying mechanism.

    It is well known that granulosa cell death via apoptosis is the main cause of atresia of antral follicles, however, whether preantral follicular attrition makes use of the same cell death pathway is not clear. Therefore, in chapter 2 I have investigated different cell death pathways in the adult rat ovary to examine whether they represent the reported histological differences between preantral and antral atretic follicles. Based on the results of studies in other organs, I used microtubule-associated light-chain protein 3 (LC3) and QSQTM1/p62 as markers of autophagy and cleaved caspase 3 (cCASP3) as marker of apoptosis, using immunohistochemistry, western blotting, and laser capture micro-dissection followed by qRT-PCR. The results showed that in the granulosa cells of atretic preantral follicles, p62 immunostaining was less intense compared to healthy preantral follicles, while no difference in LC3 immunostaining intensity was observed. In contrast, in antral follicles, no difference in both immunostaining and mRNA levels of LC3 and p62 were found between healthy and atretic follicles, indicating that autophagy was not responsible for attrition of antral follicles. cCASP3 immunostaining was scarce in the granulosa cells of atretic preantral follicles, whereas many cCASP3 positive apoptotic cells were present in atretic antral follicles, indicating that apoptosis is a major cell death pathway activated in antral follicle degeneration. Immunostaining for superoxide dismutase 2 (SOD2) was reduced in preantral and antral atretic follicles. This observation was confirmed by a concomitant down regulation of Sod2 mRNA levels. These findings suggest that preantral follicular atresia mainly makes use of autophagy as cell death pathway, while antral follicles degenerate mainly via apoptosis.

    In chapter 3, the consequences of prolonged exposure to reduced thyroid hormone concentrations in adulthood on the size of the ovarian follicle pool are investigated. Besides having a direct effect on the functioning of many cells, changes in thyroid hormone levels also influence metabolism. In this study female rats at the age of 10 weeks were given a control diet or an iodide deficient diet in combination with perchlorate supplementation to inhibit iodide uptake by the thyroid, resulting in a relatively mild chronic hypothyroid condition. At the age of 26 weeks animals were sacrificed and ovaries histologically evaluated. Plasma concentrations of relevant hormones (thyroid-stimulating hormone (TSH), tri-iodothyronine (T3), thyroxine (T4), follicle-stimulating hormone (FSH), luteinizing hormone (LH) and anti-Müllerian hormone (AMH) were determined. Primordial, primary and preantral follicle numbers were significantly lower in the hypothyroid ovaries compared to the euthyroid controls, while a downward trend in antral follicle numbers and corpora lutea was observed. The percentage of atretic follicles was not different between the two groups. Plasma AMH concentrations showed a significant correlation with the growing follicle population represented by the total number of primary, preantral and antral follicles per ovary. The data indicate that prolonged mild hypothyroidism negatively affects ovarian follicular reserve as well as the size of the growing follicle population, which may impact fertility. AMH can serve, also under mild hypothyroid conditions, as a surrogate marker to assess the size of the growing ovarian follicle population, offering a non-invasive way to evaluate the correlation between female reproductive health and thyroid status.

    Subsequently, in chapter 4, the long-term effects of chronic hypothyroidism initiated already in the foetal/neonatal period on ovarian follicular development were investigated. In contrast to the experiments described in chapter 3, the rats in this experiment were exposed to reduced thyroid hormone levels from the moment of conception until necropsy. Effects on the ovarian follicular reserve and ovulation rate in prepubertal (12-day-old) and adult (64-day-old and 120-day-old) rats were studied. Besides, antioxidant gene expression, mitochondrial density and the occurrence of oxidative stress were analyzed. The results of this investigation showed that continuous fetal/postnatal hypothyroidism resulted in lower preantral and antral follicle numbers in adulthood, accompanied by a higher percentage of atretic follicles, when compared to euthyroid age-matched controls. Not surprisingly, ovulation rate was lower in the hypothyroid rats. At the age of 120 days, the mRNA and protein content of superoxide dismutase 1 (SOD1) was significantly increased, while catalase (CAT) mRNA and protein content was significantly decreased, suggesting a disturbed antioxidant defense capacity of ovarian cells in the hypothyroid animals. This was supported by a significant reduction in peroxiredoxin 3 (Prdx3), thioredoxin reductase 1 (Txnrd1), and uncoupling protein 2 (Ucp2) mRNA content and a downward trend in glutathione peroxidase 3 (Gpx3) and glutathione S-transferase mu 2 (Gstm2) mRNA content. These changes in gene expression were likely responsible for the increased immunostaining of the oxidative stress marker 4-hydroxynonenal. Together these results suggest that chronic hypothyroidism initiated in the foetal/neonatal period resulted in a decreased ovulation rate associated with a disturbance of the antioxidant defense system in the ovary. In contrast to hypothyroidism induced in adulthood (chapter 3), no reduction in primordial or primary follicle numbers was observed, suggesting that the ovarian reserve was not affected.

    Chapter 5 addressed the question what the consequences were of a change in nutrient flux on ovarian follicular development. In this chapter mice were employed that ectopically express uncoupling protein 1 (UCP1) in skeletal muscle (UCP1-TG). This did not affect adiposity, but led to a redistribution of energy sources away from the ovaries towards skeletal muscle tissue,; a model of skeletal muscle pseudo-starvation. The results showed that UCP1-TG female mice had increased energy expenditure, reduced body size, unchanged adiposity, increased plasma fibroblast growth factor 21 (FGF21) concentrations and reduced insulin-like growth factor 1 (IGF1) levels. UCP1-TG mice had a 30% lower number of healthy follicle compared to WT mice. Primary and preantral follicle numbers were decreased by 40%, while the number of atretic follicles was significantly increased and corpora lutea (CL) were absent in 40% of the ovaries of UCP1-TG mice. The latter suggested that these mice did not ovulate and thus were infertile. The elevated circulating FGF21 concentrations were not responsible for the ovarian phenotype, since UCP1-TG and UCP1-TG/FG21-/- mice show the same ovarian follicular phenotype. Significant correlation of circulating IGF1 levels with antral follicle, CL numbers and differentially activated AKT in healthy antral follicles and activated IRS2 in atretic follicles between WT and UCP1-TG mice shows, that IGF1 is, at least partly, responsible for the ovarian phenotype of these mice. Together, our data show that an energy drain towards skeletal muscle tissue negatively impacts growing pool of ovarian follicles and ovulation rate in female mice, which is, at least in part, mediated by IGF1, and not by FGF21.

    In conclusion, the results of my thesis research shows that preantral atresia occurs mainly through autophagy. Dietary induced chronic hypothyroidism, an intervention that reduces basal metabolic rate, initiated either during foetal/neonatal or adulthood impairs ovarian follicle development. The age at onset of hypothyroidism modified the effects of this condition on ovarian follicular development. A change in nutrient flux away from the ovaries towards skeletal muscle tissue negatively affects ovarian follicle development. Overall, the results of my thesis have provided new insights in the mechanisms of follicular attrition and shows that conditions that alter metabolic fuel use impact on ovarian follicular development.

    Programme on Integrated Seed Sector Development in Ethiopia : 2015 Annual report
    Walsh, Stephen ; Thijssen, M.H. - \ 2016
    Centre for Development Innovation (Report CDI-16-012 ) - 45
    seeds - seed production - agroindustrial sector - entrepreneurship - businesses - development - ethiopia - zaden - zaadproductie - agro-industriële sector - ondernemerschap - bedrijven - ontwikkeling - ethiopië
    The programme on Integrated Seed Sector Development in Ethiopia aims to strengthen the development of a vibrant, market-oriented and pluralistic seed sector in the country, where quality seed of superior varieties is available and affordable for a larger number of farmers, thereby contributing to food security and economic development in Ethiopia. The programme is a joint effort of Bahir Dar University, Haramaya University, Hawassa University, Mekelle University, Oromia Seed Enterprise, the Ethiopian Seed Association and Centre for Development Innovation of Wageningen UR. Partners include governmental organizations at federal, regional and local level, non-governmental organizations, development organizations, and seed businesses operating at different scales. The programme is funded by the Directorate General for International Cooperation through the Embassy of the Kingdom of the Netherlands in Addis Ababa.
    Reflection of a collective learning journey : Strengthening KCCEM to build the capacity of Conservation professionals in the Albertine Rift Region NICHE/RWA/025
    Oosten, C.J. van - \ 2016
    Centre for Development Innovation (Report CDI-16-014 ) - 130
    training - learning - professional competence - colleges - development - nature conservation - wildlife conservation - environmental management - tourism - rwanda - opleiding - leren - vakbekwaamheid - colleges - ontwikkeling - natuurbescherming - wildbescherming - milieubeheer - toerisme - rwanda
    Together with our support team from the Netherlands (Wageningen University), South Africa (South African Wildlife College) and Cameroon (Ecole de Faune) we embarked upon this journey of supporting the Kitabi College of Conservation and Environmental Management in Rwanda (KCCEM). The major building blocks of this learning journey are the development of a business model, the development of organisational capacity to implement the model, and the development of a range of products and services to be delivered with quality. All these three components operationalised within the policy frameworks and institutional context of Rwanda’s conservation, tourism and environmental management sector.
    Intestinal immune maturation is accompanied by temporal changes in the composition of the microbiota
    Hartog, C.G. den; Vries Reilingh, G. de; Wehrmaker, A.M. ; Savelkoul, H.F.J. ; Parmentier, H.K. ; Lammers, A. - \ 2016
    Beneficial Microbes 7 (2016)5. - ISSN 1876-2883 - p. 677 - 685.
    IgA - development - homeosta - intestine - oponisation of bacteria
    In animals establishment of the intestinal microbial ecosystem is influenced by mucosal immune functions. As mucosal immune functions dynamically change during development of juvenile layer chicken, this study focused on dynamics in the ileal microbiota composition in relation to intestinal immune development. In addition, the levels of immunoglobulin (Ig) in serum and amount of bacteria coated with IgA, a hallmark of intestinal immune maturation, were analysed. The composition of the intestinal microbiota transiently changed at the age of 14-42 days compared to the microbiota composition before and after this period. This temporal deviation in microbiota composition was associated to a temporal increase in transcriptional activity of pro-inflammatory cytokine genes. Furthermore, before week two limited amounts of faecal bacteria were bound by IgM and from week two increasing amounts of bacteria were bound by IgA, reaching a maximal level of 70% of IgA-coated bacteria at 6 weeks of age. These data could indicate that prior to achievement of intestinal homeostasis at 6-10 weeks post hatch, activation of inflammatory pathways cause a temporal disturbance of the microbiota composition. This period of imbalance may be essential for adequate immune development and establishment of intestinal homeostasis.
    The MSP guide : How to design and facilitate multi-stakeholder partnerships
    Brouwer, J.H. ; Woodhill, A.J. ; Hemmati, M. ; Verhoosel, K.S. ; Vugt, S.M. van - \ 2016
    Wageningen : Practical Action Publishing Ltd - ISBN 9781853399657 - 180
    multi-stakeholder processen - samenwerking - vennootschappen - ontwerp - governance - duurzame ontwikkeling - duurzaamheid (sustainability) - sociaal leren - innovaties - ontwikkeling - multi-stakeholder processes - cooperation - partnerships - design - governance - sustainable development - sustainability - social learning - innovations - development
    Chromatin and epigenetics in all their states : Meeting report of the first conference on Epigenetic and Chromatin Regulation of Plant Traits - January 14 – 15, 2016 - Strasbourg, France
    Bey, Till ; Jamge, Suraj ; Klemme, Sonja ; Komar, Dorota Natalia ; Gall, Sabine Le; Mikulski, Pawel ; Schmidt, Martin ; Zicola, Johan ; Berr, Alexandre - \ 2016
    Epigenetics 11 (2016)8. - ISSN 1559-2294 - p. 625 - 634.
    Chromatin reprogramming - development - enhancers - epigenetics and heritability - nuclear organization - plants

    In January 2016, the first Epigenetic and Chromatin Regulation of Plant Traits conference was held in Strasbourg, France. An all-star lineup of speakers, a packed audience of 130 participants from over 20 countries, and a friendly scientific atmosphere contributed to make this conference a meeting to remember. In this article we summarize some of the new insights into chromatin, epigenetics, and epigenomics research and highlight nascent ideas and emerging concepts in this exciting area of research.

    Natural variation in rosette size under salt stress conditions corresponds to developmental differences between Arabidopsis accessions and allelic variation in the LRR-KISS gene
    Julkowska, Magdalena M. ; Klei, Karlijn ; Fokkens, Like ; Schranz, Eric - \ 2016
    Journal of Experimental Botany 67 (2016)8. - ISSN 0022-0957 - p. 2127 - 2138.
    Arabidopsis - development - GWAS - natural variation - rosette size - salt stress

    Natural variation among Arabidopsis accessions is an important genetic resource to identify mechanisms underlying plant development and stress tolerance. To evaluate the natural variation in salinity stress tolerance, two large-scale experiments were performed on two populations consisting of 160 Arabidopsis accessions each. Multiple traits, including projected rosette area, and fresh and dry weight were collected as an estimate for salinity tolerance. Our results reveal a correlation between rosette size under salt stress conditions and developmental differences between the accessions grown in control conditions, suggesting that in general larger plants were more salt tolerant. This correlation was less pronounced when plants were grown under severe salt stress conditions. Subsequent genome wide association study (GWAS) revealed associations with novel candidate genes for salinity tolerance such as LRR-KISS (At4g08850), flowering locus KH-domain containing protein and a DUF1639-containing protein. Accessions with high LRR-KISS expression developed larger rosettes under salt stress conditions. Further characterization of allelic variation in candidate genes identified in this study will provide more insight into mechanisms of salt stress tolerance due to enhanced shoot growth.

    Advocacy for Development: Effectiveness, Monitoring and Evaluation
    Barrett, J.B. ; Wessel, M.G.J. van; Hilhorst, D.J.M. ; Arensman, B. ; Klaver, D.C. ; Richert, Wolfgang ; Bodegom, A.J. van; Waegeningh, C. van; Rasch, E.D. ; Wagemakers, A. - \ 2016
    Wageningen : Wageningen University, Wageningen UR - 98
    development - monitoring - evaluation - ontwikkeling - monitoring - evaluatie
    Monitoring and evaluation of advocacy for development is an emerging field. Many CSOs, donors and evaluators are now involved with advocacy. Questions of how to understand and assess programmes are urgent. This e-book seeks to contribute to practical capacity on this front on the basis of lessons learned during the largest evaluation of advocacy for development in history.
    Contribution of Fisheries and Aquaculture to Food Security and Poverty Reduction: Assessing the Current Evidence
    Béné, C. ; Arthur, R. ; Norbury, H. ; Allison, E.H. ; Beveridge, M. ; Bush, S.R. ; Campling, L. ; Leschen, W. ; Little, D. ; Squires, D. ; Thilsted, S.H. ; Troell, M. ; Williams, M. - \ 2016
    World Development 79 (2016). - ISSN 0305-750X - p. 177 - 196.
    poverty reduction - food security and nutrition - development - fisheries - aquaculture
    Following a precise evaluation protocol that was applied to a pool of 202 articles published between 2003 and 2014, this paper evaluates the existing evidence of how and to what extent capture fisheries and aquaculture contribute to improving nutrition, food security, and economic growth in developing and emergent countries. In doing so we evaluate the quality and scientific rigor of that evidence, identify the key conclusions that emerge from the literature, and assess whether these conclusions are consistent across the sources. The results of the assessment show that while some specific topics are consistently and rigorously documented, thus substantiating some of the claims found in the literature, other areas of research still lack the level of disaggregated data or an appropriate methodology to reach consistency and robust conclusions. More specifically, the analysis reveals that while fish contributes undeniably to nutrition and food security, the links between fisheries/aquaculture and poverty alleviation are complex and still unclear. In particular national and household level studies on fisheries’ contributions to poverty alleviation lack good conceptual models and produce inconsistent results. For aquaculture, national and household studies tend to focus on export value chains and use diverse approaches. They suggest some degree of poverty alleviation and possibly other positive outcomes for adopters, but these outcomes also depend on the small-scale farming contexts and on whether adoption was emergent or due to development assistance interventions. Impacts of fish trade on food security and poverty alleviation are ambiguous and confounded by a focus on international trade and a lack of consistent methods. The influences of major drivers (decentralization, climate change, demographic transition) are still insufficiently documented and therefore poorly understood. Finally the evaluation reveals that evidence-based research and policy narratives are often disconnected, with some of the strongest and long-lasting policy narratives lacking any strong and rigorous evidence-based validation. Building on these different results, this paper identifies six key gaps facing policy-makers, development practitioners, and researchers.
    Substitution of starch for palm oil during gestation: Impact on offspring survival and hepatic gene expression in the pig
    Almond, K.L. ; Fainberg, H.P. ; Lomax, M.A. ; Bikker, P. ; Symonds, M.E. ; Mostyn, A. - \ 2015
    Reproduction Fertility and Development 27 (2015)7. - ISSN 1031-3613 - p. 1057 - 1064.
    development - liver - nutrition - pregnancy

    Piglet neonatal mortality rates are high (∼20%), so nutritional strategies to reduce this are highly desirable. Maternal fat substitution (FS) may promote the preweaning survival of piglets by improving their energy status. Therefore, the aim of the present study was to investigate the effects of FS throughout pregnancy on offspring viability, together with the gene expression of stress-related markers in the liver. Sixteen pregnant sows were randomly allocated to one of two isocaloric diets, control (C) or FS in the form of palm oil, fed from 0 to 110 days gestation. Glucose tolerance was examined on Day 108. Median and low birthweight offspring were allocated to tissue sampling at either 7 days or 6 months postnatal age. In response to a glucose tolerance test, FS sows exhibited a raised glucose area under the curve with no change in basal glucose. Average piglet mortality (up to Day 28) was increased fourfold in the FS group, with surviving median-sized piglets exhibiting significantly lower fatty acid binding protein 1 (FABP1) expression at 7 days. There were no effects on the abundance of any other stress- or metabolic-related genes examined. Thus, this study demonstrates that maternal FS throughout gestation causes maternal glucose intolerance that may be linked to the observed increase in piglet mortality. However, the surviving offspring do not exhibit any detectable differences in postnatal growth or hepatic gene profile in later life.

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