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  • 1
    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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  • 2
    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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  • 3
    Electronic Resource
    Electronic Resource
    Vacuoles as storage compartments for nitrate in barley leaves (1981)
    [s.l.] : Nature Publishing Group
    Nature 289 (1981), S. 292-294 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Vacuoles were isolated from protoplasts as described in Fig. 1 legend and purity was confirmed by phase contrast microscopy (Fig. 1 c). Contamination with intact protoplasts never exceeded 5%. Purity was further tested using marker enzymes. The specific activity of a-mannosidase11,12 was much ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/289292a0
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  • 4
    Electronic Resource
    Electronic Resource
    Mycorrhizal fungal diversity determines plant biodiversity, ecosystem variability and productivity (1998)
    [s.l.] : Macmillan Magazines Ltd.
    Nature 396 (1998), S. 69-72 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The functioning and stability of terrestrial ecosystems are determined by plant biodiversity and species composition. However, the ecological mechanisms by which plant biodiversity and species composition are regulated and maintained are not well understood. These mechanisms need to be ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/23932
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  • 5
    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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  • 6
    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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  • 7
    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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  • 8
    Electronic Resource
    Electronic Resource
    Desiccation increases sucrose levels in Ramonda and Haberlea, two genera of resurrection plants in the Gesneriaceae (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 100 (1997), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A few genera of angiosperms are known as ‘resurrection plants’ since their leaves withstand complete desiccation. In many organisms, including some resurrection plants, desiccation tolerance is associated with the accumulation of special carbohydrates. We examined whether this is also true for the two European angiosperm genera of resurrection plants, Ramonda and Haberlea in the Gesneriaceae. Using gas chromatography, non-structural carbohydrates were determined as a percentage of the dry weight in leaves of Ramonda nathaliae subjected to various desiccation regimes. Sucrose was the predominant soluble carbohydrate in all samples, and its level steadily increased from 2 to 10% during desiccation. Starch amounted to ca 2% in control leaves and disappeared completely within 8 days of desiccation. Considerable amounts (1–2.5%) of raffinose and smaller amounts of its precursor galactinol (1-a-galactosyl-myo-inositol) were present in control leaves; these carbohydrates showed only minor changes upon desiccation. Similar results were obtained when excised leaves of Ramonda nathaliae, Ramonda myconi and Haberlea rhodopensis were subjected to desiccation. These data indicate that sucrose accumulation is connected to desiccation tolerance in Gesneriaceae; the presence of raffinose may be a pre-adaptation since this sugar prevents crystallization of sucrose during drying.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1997.tb03466.x
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  • 9
    Electronic Resource
    Electronic Resource
    Trehalose and trehalase in root nodules from various legumes (1994)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 90 (1994), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Nitrogen-fixing (effective) nodules from various legume-Rhizobium combinations were analyzed for trehalose and other soluble carbohydrates using gas chromatography and for trehalase activity using biochemical assays. Whereas the bacterial disaccharide trehalose was present only in the minority of the nodules, trehalase activity was found in all of them. Extracts from determinate nodules had a higher trehalase activity than extracts from indeterminate nodules. More detailed studies were done on soybean nodules formed in interactions with two effective and 5 ineffective Bradyrhizobium japonicum strains. Only in effective soybean nodules colonized by the strain 61-A-101 was trehalose a major soluble carbohydrate. Irrespective of the wildtype strains used. effective soybean nodules contained about 10 nkat trehalase g−1 fresh weight, whereas the ineffective nodules colonized by mutant strains derived from these wildtype strains contained 2 to 30 times less trehalase. However, a clear correlation between trehalose content and trehalase activity could not be established.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1994.tb02196.x
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  • 10
    Electronic Resource
    Electronic Resource
    Pools of non-structural carbohydrates in soybean root nodules during water stress (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 98 (1996), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The aim of this study was to examine how the pools of non-structural carbohydrates in soybean nodules are affected under water stress conditions depending on the nature of the symbiont strains with particular emphasis on the plant-borne carbohydrates sucrose and pinitol, and on trehalose, a compatible solute synthesized by the bacteroids. Soybean (Glycine max [L.] Merr. cv. Maple Arrow) plants were inoculated with the nitrogen-fixing strains Bradyrhizobium japonicum 61-A-101 or USDA 110 spc4 and cultivated axenically under conditions in which nodules formed in an upper soil compartment while roots for water supply grew into a compartment filled with nutrient solution. When the nodules were well established (1 month post inoculation), 10% (w/v) PEG 6000 was added to the nutrient solution. This led to a slowly progressing, moderate water stress, as determined by measuring the decrease of transpiration, and to a decrease in nitrogen fixation. The pool sizes of the major non-structural nodule carbohydrates changed during progression of water stress. Sucrose, the major soluble carbohydrate in nodules of unstressed plants (2 and 4%, respectively of nodule dry weight depending on symbiont strain), strongly increased in nodules of stressed plants, reaching nearly 10% of dry weight. The activities of two major sucrose-consuming enzymes, sucrose synthase and alkaline invertase, decreased markedly in nodules of stressed plants. Starch decreased only transiently upon water stress. Pinitol, a cyclitol serving as compatible solute in many plants, increased more than 4 times, reaching about 1% of nodule dry weight during the stress. Trehalose, the major soluble carbohydrate synthesized by the bacteroids, increased in nodules colonized by USDA 110 spc4 from about 0.2 to 0.8% of nodule dry weight, while in nodules colonized by 61-A-101 it amounted to more than 1.5% of dry weight both with and without stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1996.tb06677.x
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