Mogelijke oorzaken van zwarte spruiten in lelie: praktijkproef bij VWS, in samenwerking met PPO

In de broeierij van lelie, en met name bij de Oriëntals, is het ontstaan van zwarte spruiten een groot probleem dat jaarlijks vele tonnen schade oplevert. Zwarte spruiten is het verschijnsel waarbij leliespruiten tijdens de bewaring in ijs geheel of gedeeltelijk zwart worden, afsterven en volledig verloren gaan voor de bloemproductie. Bij VWS is een uitgebreide praktijkproef uitgevoerd waarin bij 3 partijen van de cultivar Conca d’Or, afkomstig van verschillende telers, de rol van de volgende factoren in het ontstaan van zwarte spruiten is onderzocht: de temperatuur tussen rooien en invriezen, het moment van invriezen en de invriestemperatuur, de ademhaling van de bollen tijdens de bewaring, het zuurstofgehalte in de kisten, het vochtgehalte van het vulmiddel en het suiker- en zetmeelgehalte van de bollen tijdens de bewaring

A review of the role of spatial resolution in energy systems modelling:Lessons learned and applicability to the North Sea region

The importance of spatial resolution for energy modelling has increased in the last years. Incorporating more spatial resolution in energy models presents wide benefits, but it is not straightforward, as it might compromise their computational performance. This paper aims to provide a comprehensive review of spatial resolution in energy models, including benefits, challenges and future research avenues. The paper is divided in four parts: first, it reviews and analyses the applications of geographic information systems (GIS) for energy modelling in the literature. GIS analyses are found to be relevant to analyse how meteorology affects renewable production, to assess infrastructure needs, design and routing, and to analyse resource allocation, among others. Second, it analyses a selection of large scale energy modelling tools, in terms of how they can include spatial data, which resolution they have and to what extent this resolution can be modified. Out of the 34 energy models reviewed, 16 permit to include regional coverage, while 13 of them permit to include a tailor-made spatial resolution, showing that current available modelling tools permit regional analysis in large scale frameworks. The third part presents a collection of practices used in the literature to include spatial resolution in energy models, ranging from aggregated methods where the spatial granularity is non-existent to sophisticated clustering methods. Out of the spatial data clustering methods available in the literature, k-means and max-p have been successfully used in energy related applications showing promising results. K-means permits to cluster large amounts of spatial data at a low computational cost, while max-p ensures contiguity and homogeneity in the resulting clusters. The fourth part aims to apply the findings and lessons learned throughout the paper to the North Sea region. This region combines large amounts of planned deployment of variable renewable energy sources with multiple spatial claims and geographical constraints, and therefore it is ideal as a case study. We propose a complete modelling framework for the region in order to fill two knowledge gaps identified in the literature: the lack of offshore integrated system modelling, and the lack of spatial analysis while defining the offshore regions of the modelling framework

Screening of a PDE-focused library identifies imidazoles with in vitro and in vivo antischistosomal activity

We report the evaluation of 265 compounds from a PDE-focused library for their antischistosomal activity, assessed in vitro using Schistosoma mansoni. Of the tested compounds, 171 (64%) displayed selective in vitro activity, with 16 causing worm hypermotility/spastic contractions and 41 inducing various degrees of worm killing at 100 μM, with the surviving worms displaying sluggish movement, worm unpairing and complete absence of eggs. The compounds that did not affect worm viability (n = 72) induced a complete cessation of ovipositing. 82% of the compounds had an impact on male worms whereas female worms were barely affected. In vivo evaluation in S. mansoni-infected mice with the in vitro ‘hit’ NPD-0274 at 20 mg/kg/day orally for 5 days resulted in worm burden reductions of 29% and intestinal tissue egg load reduction of 35% at 10 days post-treatment. Combination of praziquantel (PZQ) at 10 mg/kg/day for 5 days with NPD-0274 or NPD-0298 resulted in significantly higher worm killing than PZQ alone, as well as a reduction in intestinal tissue egg load, disappearance of immature eggs and an increase in the number of dead eggs

Uptake and depuration of gold nanoparticles in Daphnia magna

This study presents a series of short-term studies (total duration 48 h) of uptake and depuration of engineered nanoparticles (ENP) in neonate Daphnia magna. Gold nanoparticles (Au NP) were used to study the influence of size, stabilizing agent and feeding on uptake and depuration kinetics and animal body burdens. 10 and 30 nm Au NP with different stabilizing agents [citrate (CIT) and mercaptoundecanoic acid (MUDA)] were tested in concentrations around 0.5 mg Au/L. Fast initial uptake was observed for all studied Au NP, with CIT stabilized Au NP showing similar rates independent of size and MUDA showing increased uptake for the smaller Au NP (MUDA 10 nm > CIT 10 nm, 30 nm > MUDA 30 nm). However, upon transfer to clean media no clear trend on depuration rates was found in terms of stabilizing agent or size. Independent of stabilizing agent, 10 nm Au NP resulted in higher residual whole-animal body burdens after 24 h depuration than 30 nm Au NP with residual body burdens about one order of magnitude higher of animals exposed to 10 nm Au NP. The presence of food (P. subcapitata) did not significantly affect the body burden after 24 h of exposure, but depuration was increased. While food addition is not necessary to ensure D. magna survival in the presented short-term test design, the influence of food on uptake and depuration kinetics is essential to consider in long term studies of ENP where food addition is necessary. This study demonstrates the feasibility of a short-term test design to assess the uptake and depuration of ENP in D. magna. The findings underlines that the assumptions behind the traditional way of quantifying bioconcentration are not fulfilled when ENPs are studied.Peer reviewed: YesNRC publication: Ye

Phenyldihydropyrazolones as Novel Lead Compounds Against Trypanosoma cruzi

As over 6 million people are infected with Chagas disease and only limited therapeutic options are available, there is an urgent need for novel drugs. The involvement of cyclic nucleotide phosphodiesterases (PDE) in the lifecycle and biological fitness of a number of protozoan parasites has been described and several of these enzymes are thought to be viable drug targets. Within this context, a PDE-focused library was screened for its ability to affect the viability of Trypanosoma cruzi parasites. 5-(3-(Benzyloxy)-4-methoxyphenyl)-2-isopropyl-4,4-dimethyl-2,4-dihydro-3H-pyrazol-3-one (4), previously reported as a human PDE4 inhibitor, was identified as a hit. Upon optimization on three positions of the phenylpyrazolone scaffold, 2-isopropyl-5-(4-methoxy-3-(pyridin-3-yl)phenyl)-4,4-dimethyl-2,4-dihydro-3H-pyrazol-3-one (34) proved to be the most active compound against intracellular forms of T. cruzi (pIC50 = 6.4) with a 100-fold selectivity with respect to toxicity toward human MRC-5 cells. Evaluation on different life stages and clinically relevant T. cruzi strains revealed that the phenylpyrazolones are not active against the bloodstream form of the Y strain but show submicromolar activity against the intracellular form of the Y- and Tulahuen strains as well as against the nitro-drug-resistant Colombiana strain. In vitro screening of phenylpyrazolones against TcrPDEB1, TcrPDEC, and TcrCYP51 showed that there was a poor correlation between enzyme inhibition and the observed phenotypic effect. Among the most potent compounds, both TcrCYP51 and non-TcrCYP51 inhibitors are identified, which were both equally able to inhibit T. cruzi in vitro

A biology-based approach for quantitative structure-activity relationships (QSARs) in ecotoxicity.

Quantitative structure-activity relationships (QSARs) for ecotoxicity can be used to fill data gaps and limit toxicity testing on animals. QSAR development may additionally reveal mechanistic information based on observed patterns in the data. However, the use of descriptive summary statistics for toxicity, such as the 4-day LC50 for fish, introduces bias and ignores valuable kinetic information in the data. Biology-based methods use all of the toxicity data in time to derive time-independent and unbiased parameter estimates. Such an approach offers whole new opportunities for mechanism-based QSAR development. In this paper, we apply the hazard model from DEBtox to analyse survival data for fathead minnows (Pimephales promelas). Different modes of action resulted in different patterns in the parameter estimates, and therefore, the toxicity data by themselves reveal insight into the actual mechanism of toxic action