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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    Varied responses by yeast-like symbionts during virulence adaptation in a monophagous phloem-feeding insect
    Ferrater, J.B. ; Naredo, A.I. ; Almazan, M.L.P. ; Jong, P.W. de; Dicke, M. ; Horgan, F.G. - \ 2015
    Arthropod-Plant Interactions 9 (2015)3. - ISSN 1872-8855 - p. 215 - 224.
    resistant rice varieties - nilaparvata-lugens homoptera - brown planthopper resistance - xylem ingestion - uric-acid - delphacidae - selection - populations - genes - aphid
    This study examines the three-way interaction between symbionts, insect herbivores and their host plants during adaptation to resistant crop varieties. We conducted a long-term selection study (20 generations of continuous rearing) with a monophagous phloem-feeder, the brown planthopper [Nilaparvata lugens (Stål)], on several resistant rice (Oryza sativa L.) varieties. Planthopper fitness and the abundance of yeast-like symbionts (YLS) were monitored throughout the selection process. N. lugens populations collected from six regions in the Philippines adapted to the resistant varieties as noted by increasing body size and increased egg-laying. Adaptation was partially through physiological and behavioral changes apparent during feeding: Planthoppers on resistant plants had relatively high levels of xylem feeding compared with planthoppers on susceptible plants. YLS densities were highly dependent on the host rice variety. However, there were no consistent trends in YLS density during host plant switching and virulence adaptation: Compared to densities in planthoppers on the standard susceptible variety Taichung Native 1 (TN1), YLS densities were consistently higher on PTB33 (resistant), similar on IR62 (resistant) and IR65482 (moderately resistant) but lower on IR22 (susceptible). Furthermore, YLS densities often remained the same despite improved planthopper fitness over generations. Our results do not support the hypothesis that changes in YLS density mediate planthopper adaptation to resistant varieties. However, slight reductions in YLS densities toward the end of selection on TN1, IR22 and IR62 may indicate that YLS have lower functional significance where varieties and environmental conditions are constant between generations.
    Adenosine 5 '-triphosphate (ATP) supplements are not orally bioavailable: a randomized, placebo-controlled cross-over trial in healthy humans
    Arts, I.C.W. ; Coolen, E.J.C.M. ; Bours, M.J.L. ; Huyghebaert, N. ; Cohen Stuart, M.A. ; Bast, A. ; Dagnelie, P.C. - \ 2012
    Journal of the International Society of Sports Nutrition 9 (2012). - ISSN 1550-2783
    low-back-pain - uric-acid - nucleoside transporters - cancer-patients - small-intestine - crohns-disease - nucleotide - triphosphate - transit - urate
    Background: Nutritional supplements designed to increase adenosine 5'-triphosphate (ATP) concentrations are commonly used by athletes as ergogenic aids. ATP is the primary source of energy for the cells, and supplementation may enhance the ability to maintain high ATP turnover during high-intensity exercise. Oral ATP supplements have beneficial effects in some but not all studies examining physical performance. One of the remaining questions is whether orally administered ATP is bioavailable. We investigated whether acute supplementation with oral ATP administered as enteric-coated pellets led to increased concentrations of ATP or its metabolites in the circulation. Methods: Eight healthy volunteers participated in a cross-over study. Participants were given in random order single doses of 5000 mg ATP or placebo. To prevent degradation of ATP in the acidic environment of the stomach, the supplement was administered via two types of pH-sensitive, enteric-coated pellets (targeted at release in the proximal or distal small intestine), or via a naso-duodenal tube. Blood ATP and metabolite concentrations were monitored by HPLC for 4.5 h (naso-duodenal tube) or 7 h (pellets) post-administration. Areas under the concentration vs. time curve were calculated and compared by paired-samples t-tests. Results: ATP concentrations in blood did not increase after ATP supplementation via enteric-coated pellets or naso-duodenal tube. In contrast, concentrations of the final catabolic product of ATP, uric acid, were significantly increased compared to placebo by similar to 50% after administration via proximal-release pellets (P = 0.003) and naso-duodenal tube (P = 0.001), but not after administration via distal-release pellets. Conclusions: A single dose of orally administered ATP is not bioavailable, and this may explain why several studies did not find ergogenic effects of oral ATP supplementation. On the other hand, increases in uric acid after release of ATP in the proximal part of the small intestine suggest that ATP or one of its metabolites is absorbed and metabolized. Uric acid itself may have ergogenic effects, but this needs further study. Also, more studies are needed to determine whether chronic administration of ATP will enhance its oral bioavailability.
    Gastrointestinal tract of the brown kiwi (Apteryx mantelli)
    Potter, M.A. ; Lentle, R.G. ; Birtles, M.J. ; Thomas, D. ; Hendriks, W.H. - \ 2006
    Journal of Zoology 270 (2006)3. - ISSN 0952-8369 - p. 429 - 436.
    avian cecum - uric-acid - digestion - nutrition - intestine - food
    The caeca of the brown kiwi Apteryx mantelli increased in length isometrically with body mass, but wall mass and thus mucosal thickness increased allometrically. Kiwi caeca are sacculate, with greater thickness of mucosa in the proximal portions. The caecal mucosa is similar to the small intestinal mucosa, with well-developed mucosal folds, villi, and crypts of Lieberkühn or intestinal glands. The solid matter in caecal digesta contained disproportionately large quantities of material that was not retained by a 75 ¿m sieve. The per cent of incombustible material (total ash) within the caeca digesta did not differ significantly from those within adjacent small intestinal or rectal segments. The fine particles within the caeca were not composed of fine crystalline uric acid; chemical analyses showed only low levels of uric acid in caecal digesta. These findings indicate that the caeca of this flightless insectivorous ratite are a site for the sequestration and fermentative digestion of fine particulate material, such as plant fibre, fragmented chitin or uric acid crystals.
    Cryptococcus allantoinivorans sp.nov., an anamorphic basidiomycetous yeast (Tremellales) physiologicallt resembling other species of the Cryptococcus laurentii complex that degrade polysaccharides and C2 compounds
    Middelhoven, W.J. - \ 2005
    Antonie van Leeuwenhoek: : Nederlandsch tijdschrift voor hygiëne, microbiologie en serologie 87 (2005)2. - ISSN 0003-6072 - p. 101 - 108.
    sole source - uric-acid - sp-nov - normal-alkylamines - aromatic-compounds - energy - carbon - systematics - putrescine - nitrogen
    A novel Cryptococcus species is proposed to accommodate a yeast strain (CBS 9604) able to assimilate allantoin as sole carbon source, a characteristic very uncommon among yeasts. By traditional methods, the strain could not be distinguished from Cryptococcus laurentii, but nucleotide sequences of the D1D2 region of the large subunit (26S) and of the ITS region of ribosomal DNA showed relationship to the Bulleromyces clade of the genus Cryptococcus (order Tremellales) with some Tremella spp. as the closest relatives. A traditional morphological and physiological description of the strain is given. Data on the assimilation of some C2 compounds and polysaccharides are provided and compared with those of other type strains of novel species of the C. laurentii complex
    The yeast flora of some decaying mushrooms on trunks of living trees
    Middelhoven, W.J. - \ 2004
    Folia Microbiologica 49 (2004)5. - ISSN 0015-5632 - p. 569 - 573.
    sole source - uric-acid - systematics - energy - carbon
    Several ascomycetous and basidiomycetous yeasts were isolated from rotten mushrooms on the trunks of beech and tamarisk trees. One strain, identified as the novel species Cryptococcus allantoinivorans, assimilated allantoin as the sole carbon source. Phylogenetically it belongs to the C. laurentii complex, Papiliotrema bandonii being the closest relative. Some ascomycetous strains could not be distinguished from Pichia guillermondii, but deviated considerably in rDNA sequences. In addition to these species, both decaying mushrooms were inhabited by more common species, viz. Candida albicans, C. saitoana, Rhodotorula mucilaginosa, Trichosporon asahii, T. multisporum and T. porosum. The basidiomycetous yeasts, except R. mucilaginosa, assimilated some polysaccharides of plant origin.
    Systematics of the anamorphic basidiomycetous yeast genus Trichosporon Behrend with the description of the five novel species: Trichosporon vadense, T. smithiae, T. dehoogii, T. scarabaeorum and T. gamsii
    Middelhoven, W.J. ; Scorzetti, G. ; Fell, J.W. - \ 2004
    International Journal of Systematic and Evolutionary Microbiology 54 (2004)3. - ISSN 1466-5026 - p. 975 - 986.
    sp nov. - aromatic-compounds - benzene compounds - sole source - uric-acid - identification - energy - carbon
    Phylogenetic trees of the anamorphic basichomycetous yeast genus Trichosporon Behrend, based on molecular sequence analysis of the internal transcribed spacer region and the D1/D2 region of the large subunit of ribosomal (26S) DNA, are presented. This study includes three novel species from soils, Trichosporon vadense sp. nov. (type strain, CBS 8901(T)), Trichosporon smithiae sp. nov. (type strain, CBS 8370(T)) and Trichosporon gamsii sp. nov. (type strain, CBS 8245(T)), one novel species from an insect, Trichosporon scarabaeorum sp. nov. (type strain, CBS 5601(T)) and one species of unknown origin, Trichosporon dehoogii sp. nov. (type strain, CBS 8686(T)). The phylogenetic positions and physiological characteristics that distinguish the new taxa from related species, based partly on growth tests that are not traditionally used in yeast taxonomy (uric acid, ethylamine, L-4-hydroxyproline, tyramine and L-phenylalanine as sources of carbon and nitrogen, and polygalacturonate, quinate, 4-ethylphenol, phloroglucinol, 2,3-dihydroxybenzoate and orcinol as sole carbon sources), are discussed. Assimilation of L-rhamnose and erythritol and maximum growth temperature were also used to delineate species.
    Relation between phylogeny and physiology in some ascomycetous yeasts
    Middelhoven, W.J. ; Kurtzman, C.P. - \ 2003
    Antonie van Leeuwenhoek: : Nederlandsch tijdschrift voor hygiëne, microbiologie en serologie 83 (2003). - ISSN 0003-6072 - p. 69 - 74.
    normal-alkylamines - sole source - uric-acid - adenine - carbon - energy - nov
    The question of whether yeasts with similar physiological properties are closely related has been examined using recently published phylogenetic analyses of 26S domain D1/D2 rDNA nucleotide sequences from all currently recognized ascomycetous yeasts. When apparently unique metabolic pathways are examined, some relationships between physiology and rDNA phylogeny are evident. Most Candida and Pichia species that are able to assimilate methanol as the sole carbon source are in a clade delimited by C. nanospora and C. boidinii. Exceptions are P. capsulata and P. pastoris which are phylogenetically separated from the other methanol-assimilating yeasts. Yeasts subject to the petite mutation, resulting in respiratory deficiency, belong to three different clades, viz. a Saccharomyces clade delimited by S. cerevisiae and S. rosinii, the Dekkera/Brettanomyces clade, and some Schizosaccharomyces species ('Archiascomycete' clade). However, petite mutants were also found in Zygosaccharomyces fermentati and some other more distantly related species. Yeasts able to assimilate n-hexadecane, uric acid or amines as sole carbon source are broadly distributed over the ascomycetous phylogenetic tree. However, species that assimilate adenine as sole carbon source are closely related. Most of these species also assimilated glycine, uric acid, n-hexadecane, putrescine and branched-chain aliphatic compounds such as isobutanol, leucine and isoleucine. Among the Saccharomycetales, species utilizing all or the great majority of these eight compounds are in the Stephanoascus/Arxula/Blastobotrys clade. Candida blankii, which is distantly related to this clade, proved to be an exception and assimilated six of eight of these compounds.
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