Publications by authors named "Ronald De Vries"

Much remains to be learned about the biology of mushroom-forming fungi, which are an important source of food, secondary metabolites and industrial enzymes. The wood-degrading fungus Schizophyllum commune is both a genetically tractable model for studying mushroom development and a likely source of enzymes capable of efficient degradation of lignocellulosic biomass. Comparative analyses of its 38.

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The presence of a mannitol cycle in fungi has been subject to discussion for many years. Recent studies have found no evidence for the presence of this cycle and its putative role in regenerating NADPH. However, all enzymes of the cycle could be measured in cultures of Aspergillus niger.

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Article Synopsis
  • L-arabitol dehydrogenase (LAD) and xylitol dehydrogenase (XDH) are enzymes that degrade common sugars, L-arabinose and D-xylose, with XDH also showing activity on D-sorbitol, unlike LAD.
  • A phylogenetic analysis revealed that these enzymes, along with D-sorbitol dehydrogenases (SDH), evolved from a common ancestor, forming three distinct groups.
  • The study identified two specific residues in LAD (M70 and Y318) that influence its ability to function with D-sorbitol, with mutations in Y318 increasing its activity with L-arabitol and xylitol while enhancing affinity for D-sorbitol.
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The plant polysaccharide degradative potential of Aspergillus nidulans was analysed in detail and compared to that of Aspergillus niger and Aspergillus oryzae using a combination of bioinformatics, physiology and transcriptomics. Manual verification indicated that 28.4% of the A.

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Background: Aspergillus niger is an ascomycetous fungus that is known to reproduce through asexual spores, only. Interestingly, recent genome analysis of A. niger has revealed the presence of a full complement of functional genes related to sexual reproduction 1.

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The Hypocrea jecorina LXR1 was described as the first fungal L-xylulose reductase responsible for NADPH dependent reduction of L-xylulose to xylitol in L-arabinose catabolism. Phylogenetic analysis now reveals that LXR1 forms a clade with fungal D-mannitol 2-dehydrogenases. Lxr1 and the orthologous Aspergillus niger mtdA are not induced by L-arabinose but expressed at low levels during growth on different carbon sources.

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With the recent publication of the FDA guidance on metabolites in safety testing (MIST), a reflection is provided that describes the impact of this guidance on the processes of drug metabolite identification and quantification at various stages of drug development. First, a retrospective analysis is described that was conducted on 12 human absorption, metabolism, and excretion (AME) trials with the application of these MIST criteria. This analysis showed that the number of metabolites requiring identification, (semi)-quantification, and coverage in the toxicology species would substantially increase.

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The identification and annotation of protein-coding genes is one of the primary goals of whole-genome sequencing projects, and the accuracy of predicting the primary protein products of gene expression is vital to the interpretation of the available data and the design of downstream functional applications. Nevertheless, the comprehensive annotation of eukaryotic genomes remains a considerable challenge. Many genomes submitted to public databases, including those of major model organisms, contain significant numbers of wrong and incomplete gene predictions.

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The white-rot fungus Phanerochaete chrysosporium produces glucuronoyl esterase, a recently discovered carbohydrate esterase, during growth on sugar beet pulp. Two putative genes encoding this enzyme, ge1 and ge2, were isolated and cloned. Heterologous expression in Aspergillus vadensis, Pycnoporus cinnabarinus and Schizophyllum commune resulted in extracellular glucuronoyl esterase activity, demonstrating that these genes encode this enzymatic function.

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Two liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) methods are described, one for the quantitative determination of risperidone and the enantiomers of its active metabolite 9-hydroxyrisperidone (paliperidone) in human plasma and the other for the determination of the enantiomers of 9-hydroxyrisperidone in human urine. The plasma method is based on solid-phase extraction of 200 microl of sample on a mixed-mode sorbent, followed by separation on a cellulose-based LC column with a 13.5-min mobile phase gradient of hexane, isopropanol and ethanol.

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Background: The dung-inhabiting ascomycete fungus Podospora anserina is a model used to study various aspects of eukaryotic and fungal biology, such as ageing, prions and sexual development.

Results: We present a 10X draft sequence of P. anserina genome, linked to the sequences of a large expressed sequence tag collection.

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Ustilago maydis establishes a biotrophic relationship with its host plant, i.e. plant cells stay alive despite massive fungal growth in infected tissue.

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A novel cold-tolerant fungus, Fibulorhizoctonia psychrophila, was isolated from a refrigerated carrot storage facility and identified as an anamorph of Athelia, often classified in Rhizoctonia s.l. Growth of this fungus was observed between 0 and 20 degrees C with an optimum at 9-12 degrees C, while incubation of mycelium grown at 15-32 degrees C resulted in absence of growth even after the fungus was transferred back to 15 degrees C.

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Feruloyl esterases are part of the enzymatic spectrum employed by fungi and other microorganisms to degrade plant polysaccharides. They release ferulic acid and other aromatic acids from these polymeric structures and have received an increasing interest in industrial applications such as in the food, pulp and paper and bio-fuel industries. This review provides an overview of the current knowledge on fungal feruloyl esterases focussing in particular on the differences in substrate specificity, regulation of their production, prevalence of these enzymes in fungal genomes and industrial applications.

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Fungal mycelia are exposed to heterogenic substrates. The substrate in the central part of the colony has been (partly) degraded, whereas it is still unexplored at the periphery of the mycelium. We here assessed whether substrate heterogeneity is a main determinant of spatial gene expression in colonies of Aspergillus niger.

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The fungus Ustilago maydis is a biotrophic pathogen parasitizing on maize. The most prominent symptoms of the disease are large tumors in which fungal proliferation and spore differentiation occur. In this study, we have analyzed early and late tumor stages by confocal microscopy.

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One type of covalent linkages connecting lignin and hemicellulose in plant cell walls is the ester linkage between 4-O-methyl-D-glucuronic acid of glucuronoxylan and lignin alcohols. An enzyme that could hydrolyze such linkages, named glucuronoyl esterase, occurs in the cellulolytic system of the wood-rotting fungus Schizophyllum commune. Here we report partial amino acid sequences of the enzyme and the results of subsequent search for homologous genes in sequenced genomes.

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A novel culturing technique, called the ring-plate system, is described. Fungal colonies are grown on a polycarbonate membrane placed on a plate with 6 ring-shaped wells that are filled with liquid medium. This culturing technique enables simultaneous monitoring of environmental conditions and secretion in different parts of the fungal colony.

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The filamentous fungus Aspergillus niger is widely exploited by the fermentation industry for the production of enzymes and organic acids, particularly citric acid. We sequenced the 33.9-megabase genome of A.

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Ustilago maydis is a ubiquitous pathogen of maize and a well-established model organism for the study of plant-microbe interactions. This basidiomycete fungus does not use aggressive virulence strategies to kill its host. U.

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Compatible solutes are components that can be quickly accumulated and degraded inside fungal cells. They do not disturb the functioning of proteins and protect the cell under adverse conditions. In this issue of the Biochemical Journal, Solomon and co-workers evaluate the role of mannitol, one of these components, in Stagonospora nodorum, a plant-pathogenic fungus, and find surprising effects on the development of spores and spore-forming structures.

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A strain from the group of black Aspergilli was analysed in detail to determine the species to which it belongs. A detailed analysis of morphology, RFLP patterns and metabolite profiles was carried out. In addition, a phylogenetic tree was constructed for the black Aspergilli using the ITS and the beta-tubulin sequences of the individual strains.

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A new species of the group of black aspergilli, Aspergillus vadensis, was analyzed for its potential as a host for homologous and heterologous protein production. Unlike the other black aspergilli, this strain does not acidify the culture medium when nitrate is the nitrogen source and only produces very low levels of extracellular proteases, mainly serine metalloproteases. The stability of A.

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Aims: An in vitro study has suggested that risperidone is a substrate of P-glycoprotein, which is coded by MDR-1 gene. Thus, we studied the effects of major polymorphisms of the MDR-1 gene on plasma drug concentrations.

Methods: Subjects were 85 schizophrenic patients receiving 3 mg twice daily of risperidone.

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