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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When animals speak : Toward an interspecies democracy
Meijer, Eva - \ 2019
New York : New York University Press - ISBN 9781479815661 - 228 p.
A groundbreaking argument for the political rights of animals In When Animals Speak, Eva Meijer develops a new, ground-breaking theory of language and politics, arguing that non-human animals speak--and, most importantly, act--politically. From geese and squid to worms and dogs, she highlights the importance of listening to animal voices, introducing ways to help us bridge the divide between the human and non-human world. Drawing on insights from science, philosophy, and politics, Meijer provides fascinating, real-world examples of animal communities who use their voices to speak, and act, in political ways. When Animals Speak encourages us to rethink our relations with other animals, showing that their voices should be taken into account as the starting point for a new interspecies democracy.
Wilde zwijnen op hol
Jansman, Hugh - \ 2019
Projecting terrestrial biodiversity intactness with GLOBIO 4
Schipper, Aafke M. ; Hilbers, Jelle P. ; Meijer, Johan R. ; Antão, Laura H. ; Benítez-López, Ana ; Jonge, Melinda M.J. de; Leemans, Luuk H. ; Scheper, Eddy ; Alkemade, Rob ; Doelman, Jonathan C. ; Mylius, Sido ; Stehfest, Elke ; Vuuren, Detlef P. van; Zeist, Willem Jan van; Huijbregts, Mark A.J. - \ 2019
Global Change Biology (2019). - ISSN 1354-1013
anthropocene - biodiversity scenarios - global environmental change - land-use downscaling - mean species abundance

Scenario-based biodiversity modelling is a powerful approach to evaluate how possible future socio-economic developments may affect biodiversity. Here, we evaluated the changes in terrestrial biodiversity intactness, expressed by the mean species abundance (MSA) metric, resulting from three of the shared socio-economic pathways (SSPs) combined with different levels of climate change (according to representative concentration pathways [RCPs]): a future oriented towards sustainability (SSP1xRCP2.6), a future determined by a politically divided world (SSP3xRCP6.0) and a future with continued global dependency on fossil fuels (SSP5xRCP8.5). To this end, we first updated the GLOBIO model, which now runs at a spatial resolution of 10 arc-seconds (~300 m), contains new modules for downscaling land use and for quantifying impacts of hunting in the tropics, and updated modules to quantify impacts of climate change, land use, habitat fragmentation and nitrogen pollution. We then used the updated model to project terrestrial biodiversity intactness from 2015 to 2050 as a function of land use and climate changes corresponding with the selected scenarios. We estimated a global area-weighted mean MSA of 0.56 for 2015. Biodiversity intactness declined in all three scenarios, yet the decline was smaller in the sustainability scenario (−0.02) than the regional rivalry and fossil-fuelled development scenarios (−0.06 and −0.05 respectively). We further found considerable variation in projected biodiversity change among different world regions, with large future losses particularly for sub-Saharan Africa. In some scenario-region combinations, we projected future biodiversity recovery due to reduced demands for agricultural land, yet this recovery was counteracted by increased impacts of other pressures (notably climate change and road disturbance). Effective measures to halt or reverse the decline of terrestrial biodiversity should not only reduce land demand (e.g. by increasing agricultural productivity and dietary changes) but also focus on reducing or mitigating the impacts of other pressures.

A loop-mediated isothermal amplification (LAMP) assay based on unique markers derived from genotyping by sequencing data for rapid in planta diagnosis of Panama disease caused by Tropical Race 4 in banana
Ordóñez, N. ; Salacinas, M. ; Mendes, O. ; Seidl, M.F. ; Meijer, H.J.G. ; Schoen, C.D. ; Kema, G.H.J. - \ 2019
Plant Pathology 68 (2019)9. - ISSN 0032-0862 - p. 1682 - 1693.
DArTseq - field diagnostic - Fusarium odoratissimum - LAMP - Musa - Tropical Race 4

The socio-economic impact of Fusarium odoratissimum, which is colloquially called tropical race 4 (TR4), is escalating as this fungal pathogen spreads to new banana-growing areas. Hence, the development of simple, reliable and rapid detection technologies is indispensable for implementing quarantine measures. Here, a versatile loop-mediated isothermal amplification (LAMP) assay has been developed that is applicable under field and laboratory conditions. DNA markers unique to TR4 isolates were obtained by diversity arrays technology sequencing (DArTseq), a genotyping by sequencing technology that was conducted on 27 genotypes, comprising 24 previously reported vegetative compatibility groups (VCGs) and three TR4 isolates. The developed LAMP TR4 assay was successfully tested using 22 TR4 isolates and 45 non-target fungal and bacterial isolates, as well as on infected plants under greenhouse and field conditions. The detection limit was 1 pg µL−1 pure TR4 DNA or 102 copies plasmid-localized TR4 unique sequence (SeqA) per reaction, which was not affected by background DNA in complex samples. The LAMP TR4 assay offers a powerful tool for the routine and unambiguous identification of banana plants infected with TR4, contributing to advanced diagnosis in field situations and monitoring of fusarium wilt.

Toll-Like Receptor-dependent immunomodulatory activity of Pycnogenol
Verlaet, Annelies A.J. ; Bolt, Nieke van der; Meijer, Ben ; Breynaert, Annelies ; Naessens, Tania ; Konstanti, Prokopis ; Smidt, Hauke ; Hermans, Nina ; Savelkoul, Huub ; Teodorowicz, Gosia - \ 2019
Wageningen University
PRJEB29793 - ERP112142
Background: Pycnogenol® (PYC), a patented herbal extract of French maritime pine bark, consists of a complex mixture of bioflavonoids. The main constituents of PYC are procyanidins; biopolymers consisting of units of catechin (CAT) and epicatechin. PYC is shown to exert immunomodulatory properties, nevertheless its underlying mechanisms are not yet fully elucidated. Methods: In this study, the effect of PYC and its constituent CAT on membrane Toll like receptor (TLR) activity was examined using stably transfected Human Embryonic Kidney cells. The Human monocytic leukaemia cell line THP-1 was used to examine the effect of PYC and CAT on pro-inflammatory cytokine release.Findings: We showed that non-metabolised PYC acts as agonist of TLR1/2, TLR2/6 and a partial agonist of TLR5, which resulted in the induction of pro-inflammatory cytokine secretion from THP-1 macrophages as well as activation of Nf-κB transcription factor. This effect was altered due to gastrointestinal metabolism, which revealed immuno-suppressive potential against TLR 1/2 and TLR 2/6 of the retentate fraction compared to the control sample. Moreover, the dialysed fraction did not show potential to induce pro-inflammatory cytokine secretion by THP-1 macrophages but the capacity to induce anti-inflammatory IL-10. Moreover, we showed that PYC on its own does not activate TLR4 but the formation of complexes with lipopolysaccharides (LPS) is required to stimulate the TLR4 receptor. We found that PYC and PYC-LPS complexes to the same extend dose-dependently increase pro-inflammatory cytokine levels (IL-8, IL-1β and TNF) and upregulate phosphorylation of the transcription factor NF-ĸB. No effects for CAT were observed on TLR activation and pro-inflammatory cytokine production levels. Conclusions: Our study stresses the importance of metabolism for biological activity of PYC compounds. Moreover our results suggest that bot non-metabolised as well as metabolised PYC acts via TLR 1/2 and TLR 2/6 next to TLR4.
CRISPR/Cas inactivation of RECQ4 increases homeologous crossovers in an interspecific tomato hybrid
Maagd, Ruud A. de; Loonen, Annelies ; Chouaref, Jihed ; Pelé, Alexandre ; Meijer-Dekens, Fien ; Fransz, Paul ; Bai, Yuling - \ 2019
Plant Biotechnology Journal (2019). - ISSN 1467-7644
class II crossover pathway - interspecific crosses - introgression breeding - meiosis - RECQ4

Crossover formation during meiosis in plants is required for proper chromosome segregation and is essential for crop breeding as it allows an (optimal) combination of traits by mixing parental alleles on each chromosome. Crossover formation commences with the production of a large number of DNA double-strand breaks, of which only a few result in crossovers. A small number of genes, which drive the resolution of DNA crossover intermediate structures towards non-crossovers, have been identified in Arabidopisis thaliana. In order to explore the potential of modification of these genes in interspecific hybrids between crops and their wild relatives towards increased production of crossovers, we have used CRISPR/Cas9-mutagenesis in an interspecific tomato hybrid to knockout RecQ4. A biallelic recq4 mutant was obtained in the F1 hybrid of Solanum lycopersicum and S. pimpinellifolium. Compared with the wild-type F1 hybrid, the F1 recq4 mutant was shown to have a significant increase in crossovers: a 1.53-fold increase when directly observing ring bivalents in male meiocytes microscopically and a 1.8-fold extension of the genetic map when measured by analysing SNP markers in the progeny (F2) plants. This is one of the first demonstrations of increasing crossover frequency in interspecific hybrids by manipulating genes in crossover intermediate resolution pathways and the first to do so by directed mutagenesis. Significance statement: Increasing crossover frequency during meiosis can speed up or simplify crop breeding that relies on meiotic crossovers to introduce favourable alleles controlling important traits from wild relatives into crops. Here we show for the first time that knocking out an inhibitor of crossovers in an interspecific hybrid between tomato and its relative wild species using CRISPR/Cas9-mutagenesis results in increased recombination between the two genomes.

Pfcyp51 exclusively determines reduced sensitivity to 14α-demethylase inhibitor fungicides in the banana black Sigatoka pathogen Pseudocercospora fijiensis
Chong, Pablo ; Vichou, Aikaterini Eleni ; Schouten, Henk J. ; Meijer, Harold J.G. ; Arango Isaza, Rafael E. ; Kema, Gert H.J. - \ 2019
PLoS ONE 14 (2019)10. - ISSN 1932-6203

The haploid fungus Pseudocercospora fijiensis causes black Sigatoka in banana and is chiefly controlled by extensive fungicide applications, threatening occupational health and the environment. The 14α-Demethylase Inhibitors (DMIs) are important disease control fungicides, but they lose sensitivity in a rather gradual fashion, suggesting an underlying polygenic genetic mechanism. In spite of this, evidence found thus far suggests that P. fijiensis cyp51 gene mutations are the main responsible factor for sensitivity loss in the field. To better understand the mechanisms involved in DMI resistance, in this study we constructed a genetic map using DArTseq markers on two F1 populations generated by crossing two different DMI resistant strains with a sensitive strain. Analysis of the inheritance of DMI resistance in the F1 populations revealed two major and discrete DMI-sensitivity groups. This is an indicative of a single major responsible gene. Using the DMI-sensitivity scorings of both F1 populations and the generation of genetic linkage maps, the sensitivity causal factor was located in a single genetic region. Full agreement was found for genetic markers in either population, underlining the robustness of the approach. The two maps indicated a similar genetic region where the Pfcyp51 gene is found. Sequence analyses of the Pfcyp51 gene of the F1 populations also revealed a matching bimodal distribution with the DMI resistant. Amino acid substitutions in P. fijiensis CYP51 enzyme of the resistant progeny were previously correlated with the loss of DMI sensitivity. In addition, the resistant progeny inherited a Pfcyp51 gene promoter insertion, composed of a repeat element with a palindromic core, also previously correlated with increased gene expression. This genetic approach confirms that Pfcyp51 is the single explanatory gene for reduced sensitivity to DMI fungicides in the analysed P. fijiensis strains. Our study is the first genetic analysis to map the underlying genetic factors for reduced DMI efficacy.

Boeren op de barricaden: 7 feiten en fabels
Daatselaar, C.H.G. ; Rabbinge, R. - \ 2019
Effects of selected insecticides on Black Soldier Fly (Hermetia illucens) larvae
Meijer, N.P. ; Rijk, T.C. de; Loon, J.J.A. van; Fels, H.J. van der - \ 2019
Aflatoxin B1 Conversion by Black Soldier Fly (Hermetia illucens) Larval Enzyme Extracts
Meijer, Nathan ; Stoopen, Geert ; Fels-Klerx, H.J. van der; Loon, Joop J.A. van; Carney, John ; Bosch, Guido - \ 2019
Toxins 11 (2019)9. - ISSN 2072-6651
aflatoxin - black soldier fly - BSFL - cytochrome P450 - enzyme induction - Hermetia illucens - metabolic conversion - mycotoxin - S9 fraction

The larvae of the black soldier fly (Hermetia illucens L., BSFL) have received increased industrial interest as a novel protein source for food and feed. Previous research has found that insects, including BSFL, are capable of metabolically converting aflatoxin B1 (AFB1), but recovery of total AFB1 is less than 20% when accounting for its conversion to most known metabolites. The aim of this study was to examine the conversion of AFB1 by S9 extracts of BSFL reared on substrates with or without AFB1. Liver S9 of Aroclor-induced rats was used as a reference. To investigate whether cytochrome P450 enzymes are involved in the conversion of AFB1, the inhibitor piperonyl butoxide (PBO) was tested in a number of treatments. The results showed that approximately 60% of AFB1 was converted to aflatoxicol and aflatoxin P1. The remaining 40% of AFB1 was not converted. Cytochrome P450s were indeed responsible for metabolic conversion of AFB1 into AFP1, and a cytoplasmic reductase was most likely responsible for conversion of AFB1 into aflatoxicol.

An Improved Phenotyping Protocol for Panama Disease in Banana
García-Bastidas, Fernando A. ; Veen, Alexander J.T. Van der; Nakasato-Tagami, Giuliana ; Meijer, Harold J.G. ; Arango-Isaza, Rafael E. ; Kema, Gert H.J. - \ 2019
Frontiers in Plant Science 10 (2019). - ISSN 1664-462X
Fusarium oxysporum ff. spp. cubense - microconidia - mung bean - Panama disease - phenotyping - spore production - TR4

Fusarium oxysporum (Fo) belongs to a group of soil-borne hyphomycetes that are taxonomically collated in the Fusarium oxysporum Species Complex (FOSC). Hitherto, those infecting bananas were placed in the forma specialis cubense (Foc). Recently, however, these genetically different Foc lineages were recognized as new Fusarium spp. placed in the Fusarium of Banana Complex (FOBC). A member of this complex F. odoratissimum II-5 that uniquely comprises the so-called Tropical Race 4 (TR4), is a major problem sweeping through production zones of Cavendish banana in several regions of the world. Because of this, there is an urgent need for a phenotyping method that allows the screening for resistance to TR4 of large numbers of banana genotypes. Most Fusarium species produce three types of spores: macroconidia, microconidia and the persistent chlamydospores that can contaminate soils for many years. Inoculum production has been an important bottleneck for efficient phenotyping due to the low or variable number of conidia and the elaborate laboratory procedures requiring specific infrastructure. Here, we report a rapid, simple and high-yielding spore production method for nine F. oxysporum formae speciales as well as the biocontrol species Fo47 and Fo618-12. For Fusarium spp. causing Fusarium wilt or Panama disease of banana, we used the protocol for four species comprising the recognized physiological races, including Tropical Race 4 (TR4). We subsequently tested the produced inoculum in comparative inoculation trials on banana plants to evaluate their efficiency. All assays resulted in typical symptoms within 10 weeks; significant differences in final disease ratings were observed, depending on inoculum concentration. Pouring inoculum directly onto banana plants showed the most consistent and reproducible results, as expressed in external wilting, internal discoloration and determined by real-time PCR assays on entire rhizomes. Moreover, this method allows the inoculation of 250 plants per hour by one individual thereby facilitating the phenotyping of large mutant and breeding populations.

Eva Meijer: Je kunt met een beroep op je geweten heel verkeerde dingen doen
Meijer, Eva - \ 2019
The environmental potential of the conversion of organic resources by black soldier fly larvae
Zanten, H.H.E. van; Zamprogna, A. ; Veenenbos, M.E. ; Meijer, Nathan ; Fels, I. van der; Loon, J.J.A. van; Bosch, G. - \ 2019
In: Book of Abstracts of the 70th Annual Meeting of the European Federation of Animal Science. - Wageningen Academic Publishers (EAAP books of abstracts ) - ISBN 9789086863396 - p. 157 - 157.
Spot on: managing Panama disease of banana in the Philippines
Salacinas, Maricar - \ 2019
Wageningen University. Promotor(en): G.H.J. Kema, co-promotor(en): H.J.G. Meijer. - Wageningen : Wageningen University - ISBN 9789463325400 - 179
Short-term, but not long-term, increased daytime workload leads to decreased night-time energetics in a free-living song bird
Visser, Marcel E. ; Dooremalen, Coby van; Tomotani, Barbara M. ; Bushuev, Andrey ; Meijer, Harro A.J. ; Marvelde, Luc Te; Gienapp, Phillip - \ 2019
Journal of Experimental Biology 222 (2019). - ISSN 0022-0949
Basal metabolic rate - Compensation hypothesis - Daily energy expenditure - Feeding frequency - Ficedula hypoleuca - Increased-intake hypothesis

Reproduction is energetically expensive and to obtain sufficient energy, animals can either alter their metabolic system over time to increase energy intake (increased-intake hypothesis) or reallocate energy from maintenance processes (compensation hypothesis). The first hypothesis predicts a positive relationship between basal metabolic rate (BMR) and energy expenditure (DEE) because of the higher energy demands of the metabolic system at rest. The second hypothesis predicts a trade-off between different body functions, with a reduction of the BMR as a way to compensate for increased daytime energetic expenditure. We experimentally manipulated the workload of wild pied flycatchers by adding or removing chicks when chicks were 2 and 11 days old. We then measured the feeding frequency (FF), DEE and BMR at day 11, allowing us to assess both short- and long-term effects of increased workload. The manipulation at day 2 caused an increase in FF when broods were enlarged, but no response in DEE or BMR, while the manipulation at day 11 caused an increase in FF, no change in DEE and a decrease in BMR in birds with more chicks. Our results suggest that pied flycatchers adjust their workload but that this does not lead to a higher BMR at night (no support for the increased-intake hypothesis). In the short term, we found that birds reallocate energy with a consequent reduction of BMR (evidence for the compensation hypothesis). Birds thus resort to short-term strategies to increase energy expenditure, which could explain why energy expenditure and hard work are not always correlated in birds.

Diet and growth of juvenile queen conch Lobatus gigas (Gastropoda: Strombidae) in native, mixed and invasive seagrass habitats
Boman, Erik Maitz ; Bervoets, Tadzio ; Graaf, Martin De; Dewenter, Jana ; Maitz, Anna ; Meijer Zu Schlochtern, Melanie P. ; Stapel, Johan ; Smaal, Aad C. ; Nagelkerke, Leopold A.J. - \ 2019
Marine Ecology Progress Series 621 (2019). - ISSN 0171-8630 - p. 143 - 154.
Caribbean - Halophila stipulacea - Invasive species - Mollusca - Stable isotope

Juvenile queen conch are primarily associated with native seagrass such as Thalassia testudinum in large parts of their range in the Caribbean and the southern Gulf of Mexico. Here, a number of non-native seagrass species have been introduced including Halophila stipulacea, which is natural to the Red Sea and the Indo-Pacific. In the Caribbean, H. stipulacea often creates dense continuous mats with little or no sediment exposed, compared to native seagrass, which grows much less dense. We examined the diet and growth of juvenile conch in both native, mixed, and invasive seagrass beds using stable isotope analysis and an in situ growth enclosure experiment. Organic material in the sediment (i.e. benthic diatoms and particulate organic matter) was found to be the most important source of carbon and nitrogen for juvenile queen conch in all 3 habitats investigated, and there was a significantly higher probability of positive growth in the native seagrass compared to the invasive seagrass. Due to the importance of the organic material in the sediment as a source of nutrition for juvenile conch, limited access to the sediment in the invasive seagrass can potentially cause inadequate nutritional conditions to sustain high growth rates. Thus, it is likely that there is a negative effect on juvenile queen conch growth currently inhabiting invasive seagrass beds, compared to native seagrass beds, when other potential sources of nutrition are not available.

Corrigendum: Exposure to antibiotics affects Saponin immersion-induced immune stimulation and shift in microbial composition in Zebrafish larvae
Nadal, Adrià López ; Peggs, David ; Wiegertjes, Geert F. ; Brugman, Sylvia - \ 2019
Frontiers in Microbiology 10 (2019). - ISSN 1664-302X

In the original article, there was an error. The name of the transgenic line used was incorrect. The correct name of the line is "mpeg1:mCherry/mpx:eGFPi114" Corrections have been made to the Materials and Methods subsection Animals: "Adult Tg(mpeg1:mCherry/mpx:eGFPi114) (Renshaw et al., 2006; Bernut et al., 2014) zebrafish (kindly provided by Prof. Meijer, Leiden University), expressing mCherry under the macrophage-specific mpeg1 promotor and GFP under the neutrophil-specific mpx promotor were housed in Zebtec family tanks (Tecniplast, Buguggiate, Italy) under continuous flow-through at 28°C (14/10-hour light/dark cycle) at Carus facilities (WUR, Wageningen, Netherlands). Zebrafish were fed with a mixture of Artemia 230.000 npg (Ocean Nutrition Europe, Essen, Belgium) and Tetramin Flakes (Tetra, Melle, Germany) twice per day. Embryos were obtained by natural spawning and raised with E3 water (0.10 mM NaCl in demineralized water, pH 7.6) in petri dishes at 28°C (12/12-hour light/dark cycle) (Westerfield, 2007). Dead or fungus-infected embryos were identified by microscopy and discarded in tricaine/E3 solution [8.4% (v/v) 24 mM Tricaine (Sigma-Aldrich, DL, United States) stock solution in E3]. Larval ages are expressed in days post-fertilization (dpf). From 5 dpf onward larvae were fed with live daily cultured Tetrahymena pyriformis." Materials and Methods, subsection Dose-Response Experiment Saponin Exposure: "Double Tg(mpeg1:mCherry /mpx:eGFPi114) zebrafish larvae were randomly distributed in 6 well plates (n = 20 fish/well) and exposed to different concentrations [0, 0.5, 0.7 and 1.0 mg/ml] of saponin [ultrapure Soy Saponin 95%, kindly provided by Trond Kortner NMBU Oslo Norway, origin: Organic Technologies, Coshocton, OH (Krogdahl et al., 2015)] dissolved in the E3 (10 ml solution/well) from 6-9 dpf. Mortality was registered and all media were refreshed daily. At 24 h (7 dpf) and 72 h (9 dpf) after the start of the immersion, zebrafish (n = 6-11/group) were anaesthetized embedded and imaged using fluorescent microscopy (as described below). Per time point several larvae were euthanized for further analysis with an overdose MS-222 (8.4 ml of 24 mM Tricaine (Sigma-Aldrich, DL, United States) in 100 ml E3). Pools of 5 larvae were used for RNA extraction (3 pools per group at 24 h, 7-9 pools per group at 72 h) and gene expression was measured on cDNA by Real Time PCR (as described below). Two independent experiments were performed and data were combined." Materials and Methods, subsection Fluorescent in vivo imaging: "Tg(mpeg1:mCherry/mpx:eGFPi114) zebrafish larvae were anaesthetized with tricaine/E3 solution (4.2 ml of 24 mM Tricaine (Sigma-Aldrich, DL, United States) in 100 ml E3) and embedded in 1% low melting point agarose (Thermo Fisher Scientific, MA, United States). Larvae were imaged as whole mounts with a Leica M205 FA Fluorescence Stereo Microscope. After image acquisition, pictures were analyzed with ImageJ® software (United States National Institutes of Health, Bethesda, United States). The intestinal regions were manually selected per fish on the basis of the bright light picture and subsequently copied to the green and red channel pictures (Supplementary Figure S1). Within this intestinal region individual cells were counted for each fish. Furthermore, corrected total cell fluorescence (CTCF) was measured in ImageJ® on total fish larvae by using the following formula: Integrated density-(area of total fish x mean fluorescence of the background reading)." Material and Methods, subsection Experimental Design and Sampling Strategy Antibiotics and Saponin Exposure: A graphical representation of the experimental design and analysis performed per time-point is displayed in Figure 1. To assess the effect of antibiotics, 4 dpf Tg(mpeg1:mCherry/mpx:eGFPi114) fish were randomly distributed in five 6 well-plates (n = 20 fish/well) and 3 treatment conditions were established: (1) control (E3), (2) ciprofloxacin 5 μg/L (Sigma-Aldrich, DL, United States) or (3) oxytetracycline hydrochloride 5 μg/L (Sigma-Aldrich, DL, United States) (10 ml solution/well). The dose of antibiotics was based on several reviews and experimental papers summarizing environmental concentrations of antibiotics in water environments (Ding and He, 2010; Carvalho and Santos, 2016; Watts et al., 2017; Patrolecco et al., 2018; Zhou et al., 2018b) to be at a low dose (ng-μg/L range) and not acute dose (mg/L range). At 6 dpf, 4 pools of 5 larvae were sampled to assess changes in gene expression at baseline. Moreover, at 6 dpf DNA was isolated from 3 pools of 5 larvae to investigate microbiome composition at baseline. In vivo imaging was performed on n = 10 larvae/group to visualize innate immune cells. Subsequently, after sampling, at 6 dpf ultrapure soy saponin was applied to half of the remaining larvae at a concentration 0.5 mg/ml (to induce mild immune stimulation) so each treatment group was split into two, resulting in 6 treatment groups: (1) control, (2) ciprofloxacin (5 μg/L), (3) oxytetracycline hydrochloride (5 μg/L), (4) saponin (0.5 mg/ml), (5) ciprofloxacin + saponin (5 μg/L + 0.5 mg/ml), and (6) oxytetracycline hydrochloride + saponin (5 μg/L + 0.5 mg/ml). All treatment media were refreshed daily. At 9 dpf in vivo imaging was performed on n = 10 larvae/group to visualize innate immune cells. Gene expression was performed on 4 pools of 5 larvae to investigate immune gene expression and from 3 pools of 5 larvae DNA was isolated for microbiological analysis. Because of the error reported above, corrections have also been made to the Figure legends of Figure 2 and Figure 4. The correct legends appear below. Figure 2: Effect of saponin immersion on zebrafish larvae. (A) Percent survival of zebrafish exposed to control (E3), 0.5 mg/ml saponin, 0.7 mg/ml saponin and 1 mg/ml saponin from 6-9 dpf (n = 40 fish/treatment) (Log-rank Mantel-Cox Test for Chi-square, ∗∗∗p < 0.0005). (B) Representative pictures of the saponin-treated Tg(mpeg1:mCherry/mpx:eGFPi114) fish displaying green neutrophils and red macrophages. (C) Quantification of neutrophils and macrophages in the intestinal area (n = 6-11 fish/group) (one way ANOVA Kruskal-Wallis test with Dunn's Multiple comparison Post-Test, mean ± SEM, ∗p < 0.05 ∗∗p < 0.01). Top: counted cells in intestinal area. Bottom: Corrected Total Cell Fluorescence (CTCF, measure for total fluorescent pixels in the whole fish). Two independent experiments were performed and data are combined. Figure 4: Effect of antibiotic exposure on saponin-immune-stimulation. (A) Percent survival of zebrafish exposed to control (E3), ciprofloxacin (4-9 dpf) (5 ug/L) or oxytetracycline (4-9 dpf) (5 ug/ml) + /- saponin (0.5 mg/ml) from 6-9 dpf (n = 100 fish / treatment) (Log-rank Mantel-Cox Test for Chi-square). (B) Representative pictures of the antibiotic/saponin-treated Tg(mpeg1:mCherry/mpx:eGFPi114) fish displaying green neutrophils and red macrophages. (C) Quantification of neutrophils and macrophages in the intestinal area (n = 10 fish/ group) (one way ANOVA Kruskal-Wallis test with Dunn's Multiple comparison Post-Test, mean ± SEM, ∗p < 0.05). Two independent experiments were performed and one representative experiment is shown. The authors apologize for this error and state that this does not change the scientific conclusions of the article in any way. The original article has been updated.

FeedCalculator, een app om rantsoenen voor vis te berekenen
Bosma, R.H. ; Veluw, S. van; Meijer, P. - \ 2019
Aquacultuur 34 (2019)1. - ISSN 1382-2764 - p. 20 - 23.
De Nederlandse sociale onderneming Single Spark heeft een smartphone app ontwikkeld waarmee kleine boeren en bedrijven zelf rantsoenen voor hun dieren kunnen berekenen (zie foto’s onder). Dat geeft hen de mogelijkheid goedkopere grondstoffen, zoals hun eigen oogstresten, te gebruiken en toch een optimaal rantsoen te voeren. Nadat het wereldwijd voor kippen en varkens was uitgerold, is de app in 2018 getest voor meerval en tilapia in resp. Nigeria en Benin.
Conversion of organic resources by black soldier fly larvae: Legislation, efficiency and environmental impact
Bosch, G. ; Zanten, H.H.E. van; Zamprogna, A. ; Veenenbos, M. ; Meijer, N.P. ; Fels-Klerx, H.J. van der; Loon, J.J.A. van - \ 2019
Journal of Cleaner Production 222 (2019). - ISSN 0959-6526 - p. 355 - 363.
Hermetia illucens - Insects - Life cycle assessment - Resource use efficiency

To meet the projected substantial growth in the global demand for meat, we are challenged to develop additional protein-rich feed ingredients while minimizing the use of natural resources. The larvae of the black soldier fly (BSF) have the capacity to convert low-value organic resources into a high quality protein source for pigs, chickens and fish and as such may increase both the productivity and the efficiency of the food chain. The aim of this study was to assess the environmental opportunities of BSF larvae reared on different sources using up to date literature data on the efficiency of BSF larvae in converting such resources into biomass. The current EU legislative framework was used to classify the various resources for rearing insects. Data of forty articles published until 1 September 2017 were used, reporting on in total 78 (mixtures of) resources used for growing BSF larvae. Data on the resource conversion efficiency on dry matter (DM) and N basis was presented in 11 and 5 studies, evaluating 21 and 13 resources, respectively. Resources studied included food and feed materials (A, n = 8 resources), foods not intended (anymore) for human consumption (B1, n = 4), and residual streams such as food waste (D, n = 2), and animal manure (E, n = 7). Conversion efficiency varied from 1.3 to 32.8% for DM and from 7.4 to 74.8% for N. Using life cycle assessment, our environmental results showed that resources within the legal groups (i.e. A and B1) that are, at the moment, not allowed in EU as animal feed have in general a lower impact in terms of global warming potential, energy use, and land use. On a per kg protein basis, BSF larvae reared on a resource that contains food (e.g. sorghum) and feed (e.g. dried distillers grains with solubles) products generally have higher environmental impacts than conventional feed protein sources (fishmeal and soybean meal). Using insects as feed, therefore, has potential to lower the environmental impact of food production but a careful examination of the resource is needed in terms of environmental impact, safety and economics.

Akkermansia muciniphila ameliorates the age-related decline in colonic mucus thickness and attenuates immune activation in accelerated aging Ercc1-/Δ7 mice
Lugt, B.M. van der; Beek, Adriaan A. Van; Aalvink, S. ; Meijer, B. ; Sovran, B. ; Vermeij, Wilbert P. ; Brandt, Renata M.C. ; Vos, W.M. de; Savelkoul, H.F.J. ; Steegenga, W.T. ; Belzer, C. - \ 2019
GSE126730 - Mus musculus - PRJNA523132
The use of Akkermansia muciniphila as potential therapeutic intervention is receiving increasing attention. Health benefits attributed to this bacterium include an improvement of metabolic disorders and exerting anti-inflammatory effects. The abundance of A. muciniphila is associated with a healthy gut in early mid- and later life. However, the effects of A. muciniphila on a decline in intestinal health during the aging process are not investigated yet. We supplemented accelerated aging Ercc1-/Δ7 mice with A. muciniphila for 10 weeks and investigated histological, transcriptional and immunological aspects of intestinal health. The thickness of the colonic mucus layer increased about 3-fold after long-term A. muciniphila supplementation and was even significantly thicker compared to mice supplemented with Lactobacillus plantarum WCFS1. Colonic gene expression profiles pointed towards a decreased expression of genes and pathways related to inflammation and immune function, and suggested a decreased presence of B cells in colon. Total B cell frequencies in spleen and mesenteric lymph nodes were not altered after A. muciniphila supplementation. Mature and immature B cell frequencies in bone marrow were increased, whereas B cell precursors were unaffected. These findings implicate that B cell migration rather than production was affected by A. muciniphila supplementation. Gene expression profiles in ileum pointed toward a decrease in metabolic- and immune-related processes and antimicrobial peptide production after A. muciniphila supplementation. Besides, A. muciniphila decreased the frequency of activated CD80+CD273- B cells in Peyer’s patches. Additionally, the increased numbers of peritoneal resident macrophages and a decrease in Ly6Cint monocyte frequencies in spleen and mesenteric lymph nodes add evidence for the potentially anti-inflammatory properties of A. muciniphila. Altogether, we show that supplementation with A. muciniphila prevented the age-related decline in thickness of the colonic mucus layer and attenuated inflammation and immune-related processes at old age. This study implies that A. muciniphila supplementation can contribute to a promotion of healthy aging.
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