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  • 1
    Electronic Resource
    Electronic Resource
    Arbuscular mycorrhizae in a long-term field trial comparing low-input (organic, biological) and high-input (conventional) farming systems in a crop rotation (2000)
    Springer
    Biology and fertility of soils 31 (2000), S. 150-156 
    Details
    ISSN: 1432-0789
    Keywords: Key words Arbuscular mycorrhizae ; Biological (organic) farming ; Conventional farming ; Glomus mosseae ; Winter wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Arbuscular mycorrhizal (AM) root colonization was studied in a long-term field trial in which four farming systems currently in use in Switzerland were continuously applied to a randomized set of plots at a single field site from 1978 till 1993. There were two low-input farming systems (organic and bio-dynamic) and two high-input (conventional) farming systems (according to Swiss guidelines of integrated plant production with and without farmyard manure). The systems had an identical 7-year crop rotation and tillage scheme and differed essentially only in the amount and type of fertilizer supplied and in plant protection management. The percentage of root colonization by AM fungi was determined in field samples 2–3 times over the growing season in crops in the rotation, namely in winter wheat (Triticum aestivum L. cv. Sardona), vetch-rye and grass-clover. We found the percentage of root length colonized by AM fungi to be 30–60% higher (P≤0.05) in the plants grown in soils from the low-input farming systems than in those grown in conventionally farmed soils. Approximately 50% of the variation of AM root colonization was explained by chemical properties of the soils (pH, soluble P and K, exchangeable Mg), the effect of soluble soil P being most pronounced. The potential of the field soils from the differently managed plots to cause symbiosis with AM fungi was tested in a glasshouse experiment, using wheat as a host plant. Soils from the low-input farming systems had a greatly enhanced capacity to initiate AM symbiosis. The relative differences in this capacity remained similar when propagules of the AM fungus Glomus mosseae were experimentally added to the soils, although overall root colonization by AM fungi was 2.8 times higher.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050638
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  • 2
    Electronic Resource
    Electronic Resource
    Asymmetric distribution of Concanavalin A binding sites on yeast plasmalemma and vacuolar membrane (1976)
    Springer
    Archives of microbiology 109 (1976), S. 115-118 
    Details
    ISSN: 1432-072X
    Keywords: Yeast ; Protoplasts ; Vacuoles ; Concanavalin A ; Membrane asymmetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Isolated vacuoles of Saccharomyces cerevisiae did not bind Concanavalin A (labelled with tritium or with a fluorescent dye) unless the vacuoles were rendered permeable and their inner membrane surface made accessible. Yeast protoplasts, on the other hand, bound large amounts of Concanavalin A on their surface, and the number of binding sites was not increased after a gentle lysis expected to expose also the inner surface of the plasmalemma. It is concluded that both the plasmalemma and the vacuolar membrane carry Concanavalin A binding sites exclusively on the surface opposite to the cytoplasmic matrix.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425122
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  • 3
    Electronic Resource
    Electronic Resource
    Characterization of amino acid pools in the vacuolar compartment of Saccharomyces cerevisiae (1974)
    Springer
    Archives of microbiology 101 (1974), S. 45-57 
    Details
    ISSN: 1432-072X
    Keywords: Yeast ; Spheroplasts ; Isolation ; Vacuoles-Compartmentation ; Amino Acid Pool
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Intact vacuoles are released from spheroplasts of Saccharomyces cerevisiae by means of a gentle mechanical disintegration method. They are purified by centrifugation in isotonic density gradients (flotation and subsequent sedimentation), and analyzed for their soluble amino acid content. The results indicate that about 60% of the total amino acid pool of spheroplasts is contained in the vacuoles. This may be an underestimate, as it presupposes no loss of amino acids from the vacuoles during the purification procedure. The amino acid concentration in the vecuoles is calculated to be approximately 5 times that in the cytoplasm if the total volumes of the two compartments are used for the calculation. The vacuolar amino acid pool is rich in basic amino acids, and in citrulline and glutamine, but contains a remarkably small amount of glutamate. Radioactive labeling experiments with spheroplasts indicate that the vacuolar amino acids are separated from the metabolically active pools located in the cytoplasm. This is particularly evident for the basic amino acids and glutamine; in contrast, the neutral amino acids and glutamate appear to exchange more rapidly between the cytoplasmic and the vacuolar compartments of the cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00455924
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  • 4
    Electronic Resource
    Electronic Resource
    Polybase induced lysis of yeast spheroplasts (1975)
    Springer
    Archives of microbiology 105 (1975), S. 319-327 
    Details
    ISSN: 1432-072X
    Keywords: Yeast ; Spheroplasts ; Vacuoles ; Isolation ; Basic macromolecules ; Poly-dl-lysine ; DEAE-dextran ; Transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The polybasic macromolecules DEAE-dextran (diethylaminoethyl-dextran, molecular weight 500 000) and poly-dl-lysine (molecular weight 30 000–70 000) were adsorbed with a high affinity by spheroplasts of Candida utilis and, subsequently, induced lysis. The extent of lysis of spheroplasts and of the liberated vacuoles was studied under various conditions using α-glucosidase activity and soluble arginine as cytoplasmic and vacuolar markers, respectively. Adsorption of polybases was rapidly completed even at 0°C; however, with small doses, lysis was poor at 0–12°C and extensive at temperatures above 12°C. This permitted the completion of adsorption before initiating lysis. The purified vacuoles were also sensitive to polybases though less so than the spheroplasts; however, after lysis of spheroplasts the liberated vacuoles were well protected against the action of polybases. A treatment with polybases which disrupted more than 99% of the spheroplasts left at least 70% of the vacuoles intact. Potassium chloride in high concentrations and calcium chloride in low concentrations inhibited polybase induced lysis of spheroplasts by preventing or even reversing the polybase adsorption. A polyacidic macromolecule, dextran sulfate, could prevent but not reverse the adsorption of polybase and subsequent lysis. Metabolic inhibitors reduced the susceptibility of spheroplasts to polybase induced lysis. Vacuoles isolated from polybase lysed spheroplasts still contained large pools of soluble amino acids, and their ability to transport arginine specifically is a further indication of their functional integrity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00447152
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  • 5
    Electronic Resource
    Electronic Resource
    Localization of trehalase in vacuoles and of trehalose in the cytosol of yeast (Saccharomyces cerevisiae) (1982)
    Springer
    Archives of microbiology 131 (1982), S. 298-301 
    Details
    ISSN: 1432-072X
    Keywords: Yeast ; Protoplast ; Compartmentation ; Vacuole ; Trehalose ; Trehalase ; Carbohydrate metabolism ; Saccharomyces cerevisiae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Protoplasts of Saccharomyces cerevisiae synthesized and degraded trehalose when they were incubated in a medium containing traces of glucose and acetate. Such protoplasts were gently lyzed by the polybase method and a particulate and soluble fraction was prepared. Trehalose was found in the soluble fraction and the trehalase activity mostly in the particulate fraction which also contained the vacuoles besides other cell organelles. Upon purification of the vacuoles, by density gradient centrifugation, the specific activity of trehalase increased parallel to the specific content of vacuolar markers. This indicates that trehalose is located in the cytosol and trehalase in the vacuole. It is suggested that trehalose, in addition to its role as a reserve may also function as a protective agent to maintain the cytosolic structure under conditions of stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00411175
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  • 6
    Electronic Resource
    Electronic Resource
    A constitutive, heat shock-activated neutral trehalase occurs in Schizosaccharomyces pombe in addition to the sporulation-specific acid trehalase (1991)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 84 (1991), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Trehalase was studied in Schizosaccharomyces pombe cells growing vegetatively on minimal medium and in sporulating cultures. Acid trehalase activity, measured at pH 4.2, was absent in vegetative cells and occurred only in asci, indicating that this activity represented the sporulation-specific trehalase reported previously. In contrast, neutral trehalase, measured at pH 6.0, was constitutively present in vegetative cells during the expotential and stationary growth phase as well as in asci. In vegetative cells, neutral trehalase did not sediment with cell walls, suggesting a cytoplasmic localization. Its activity increased ten-fold when growing cells were subjected to heat treatment of 2 h. Neutral trehalase from heat-treated cells had a pH optimum of 6.0 and was almost completely inhibited by 3 mM ZnCl2. Acid trehalase activity could be measured in intact asci, indicating that it is localized in the ascus cell walls, while neutral trehalase was not detectable in intact asci and appeared to be present primarily in the walls of ascospores and in the ascus epiplasm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1991.tb04574.x
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  • 7
    Electronic Resource
    Electronic Resource
    Synthesis and degradation of polyphosphate in the fission yeast Schizosaccharomyces pombe: mutations in phosphatase genes do not affect polyphosphate metabolism (1992)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 92 (1992), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The fission yeast Schizosaccharomyces pombe was found to accumulate large amounts of polyphosphate, particularly when grown on arginine as the nitrogen source. Upon transfer to a medium without phosphate, polyphosphate was degraded and served as an endogenous phosphate reserve. When phosphate was added again after a prolonged period of phosphate starvation, fission yeast cells synthesized more polyphosphate than they had contained before starvation, a phenomenon known as over-compensation. Strains carrying mutated structural genes for three different phosphatases, pho1, pho2 or pho3, degraded polyphosphate at the same rate as the wild-type strain during phosphate starvation and showed the same type of over-compensation when phosphate was added again.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1992.tb05251.x
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  • 8
    Electronic Resource
    Electronic Resource
    Trehalose synthesis is important for the acquisition of thermotolerance in Schizosaccharomyces pombe (1997)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 25 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Yeast cells show an adaptive response to a mild heat shock, resulting in thermotolerance acquisition. This is accompanied by induction of heat-shock protein (hsp) synthesis and rapid accumulation of trehalose. Genetic approaches to determine the specific role of trehalose in heat-induced thermotolerance in Saccharomyces cerevisiae have been hampered by the finding that deletion of TPS1, the gene encoding trehalose-6-phosphate synthase, causes a variety of pleiotropic effects, including inability to grow on glucose-containing media. Here, we have studied a tps1 mutant of the yeast Schizosaccharomyces pombe that reportedly has no such growth defects. We show that tps1 mutants have a serious defect in heat shock-induced acquisition of thermotolerance if conditioned at highly elevated temperatures (40–42.5°C), which, in wild-type cells, prevent hsp but not trehalose synthesis. In contrast, hsp synthesis appears to become particularly important under conditions in which trehalose synthesis is either absent (in tps1 mutant strains) or not fully induced (conditioning at moderately elevated temperatures, i.e. 35°C). In addition, pka1 mutants deficient in cAMP-dependent protein kinase were examined. Unconditioned pka1 cells had low levels of trehalose but a high basal level of thermotolerance. It was found that pka1 mutant cells, contrary to wild-type cells, accumulated large amounts of trehalose, even during a 50°C treatment. pka1 tps1 double mutants lacked this ability and showed reduced intrinsic thermotolerance, indicating a particularly important role for trehalose synthesis, which takes place during the challenging heat shock.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.4961856.x
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  • 9
    Electronic Resource
    Electronic Resource
    Structural analysis of the subunits of the trehalose-6-phosphate synthase/phosphatase complex in Saccharomyces cerevisiae and their function during heat shock (1997)
    Oxford UK : Blackwell Science Ltd
    Molecular microbiology 24 (1997), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Synthesis of trehalose in the yeast Saccharomyces cerevisiae is catalysed by the trehalose-6-phosphate (Tre6P) synthase/phosphatase complex, which is composed of at least three different subunits encoded by the genes TPS1, TPS2, and TSL1. Previous studies indicated that Tps1 and Tps2 carry the catalytic activities of trehalose synthesis, namely Tre6P synthase (Tps1) and Tre6P phosphatase (Tps2), while Tsl1 was suggested to have regulatory functions. In this study two different approaches have been used to clarify the molecular composition of the trehalose synthase complex as well as the functional role of its potential subunits. Two-hybrid analyses of the in vivo interactions of Tps1, Tps2, Tsl1, and Tps3, a protein with high homology to Tsl1, revealed that both Tsl1 and Tps3 can interact with Tps1 and Tps2; the latter two proteins also interact with each other. In addition, trehalose metabolism upon heat shock was analysed in a set of 16 isogenic yeast strains carrying deletions of TPS1, TPS2, TSL1, and TPS3 in all possible combinations. These results not only confirm the previously suggested roles for Tps1 and Tps2, but also provide, for the first time, evidence that Tsl1 and Tps3 may share a common function with respect to regulation and/or structural stabilization of the Tre6P synthase/phosphatase complex in exponentially growing, heat-shocked cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1997.3861749.x
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  • 10
    Electronic Resource
    Electronic Resource
    Epiparasitic plants specialized on arbuscular mycorrhizal fungi (2002)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 419 (2002), S. 389-392 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Over 400 non-photosynthetic species from 10 families of vascular plants obtain their carbon from fungi and are thus defined as myco-heterotrophs. Many of these plants are epiparasitic on green plants from which they obtain carbon by ‘cheating’ shared mycorrhizal fungi. Epiparasitic ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature01054
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