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  • 1
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Growth of willow-leaf mandarin (Citrus deliciosa Ten.) nucellar callus cultures without embryo formation was supported on sucrose as the sole carbon source. Somatic embryogenesis was obtained by substituting galactose for sucrose at the same concentration (0.15 M). A histocytological study revealed proliferation of young globular embryos during the first half of the 18-day culture cycle, irrespective of the carbon source. However, during the second half of the cycle, further embryo development failed in cell cultures on sucrose-containing medium. The rate of cell growth and the carbohydrate depletion of the medium were 3-fold higher on sucrose than on galactose-containing medium. Cell suspensions on sucrose differed by an increase in calcium, phosphorus, magnesium and potassium utilization soon after subculturing, followed by a sharp decrease. Finally, the phosphorus utilization rate per g dry weight formed was 2-fold higher in cell cultures on galactose during the second half of the culture cycle, coinciding with further embryo ontogenesis.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 93 (1995), S. 0 
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We are studying the cellular signaling pathway leading to pterocarpan phytoalexin biosynthesis in soybean that is induced by a branched hepta-β-glucoside originally isolated from the mycelial walls of the phytopathogenic oomycete Phytophthora sojae. Our research has focused on the specific recognition of the hepta-β-glucoside elicitor by binding proteins in soybean cells. Elicitor-binding proteins with properties expected of physiological receptors for the hepta-β-glucoside elicitor have been identified in soybean root membranes. These elicitor-binding proteins co-migrate with a plasma membrane marker (vanadate-sensitive H+-ATPase) on linear sucrose density gradients. Binding of a radio-iodinated derivative of the hepta-β-glucoside elicitor by membrane-localized elicitor-binding proteins is specific, reversible, saturable, and of high affinity (Kd≅ 1 nM). After solubilization with the nonionic detergent, n-dodecylsucrose, the elicitor-binding proteins retain their high affinity (Kd= 1.8 nM) for the radiolabeled elicitor and their binding specificity for elicitor-active oligoglucosides. A direct correlation is observed between the ability of oligoglucosides to displace labeled elicitor from the elicitor-binding proteins and the elicitor activity of the oligosaccharides. Thus, the elicitor-binding proteins recognize the same structural elements of the hepta-β-glucoside elicitor that are essential for its phytoalexin-inducing activity, suggesting that the binding proteins are physiological receptors for the elicitor. Current research is directed toward the purification of the hepta-β-glucoside elicitor-binding proteins by using ligand affinity chromatography. Purification and characterization of the hepta-β-glucoside binding proteins are among the first steps toward elucidating how the hepta-β-glucoside elicitor triggers the signal transduction pathway that ultimately leads to the synthesis of phytoalexins in soybean.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2048
    Keywords: Key words: Binding site (glucan) – Elicitor – Hepta-β-glucoside – Medicarpin –Phytophthora– Signal transduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract.  Previous studies have led to the identification and characterization of specific, high-affinity binding sites for a hepta-β-glucoside elicitor in soybean. A survey of plant species for elicitor-binding activity reveals that among the plants tested, the hepta-β-glucoside elicitor is only recognized by plants belonging to the legume family. We have characterized in detail the glucan elicitor-binding site in the model legume Medicago truncatula Gaertn., and partially characterized the site in Lotus japonicus. These sites have characteristics that are very similar to the one in soybean, with dissociation constants of 4.7 and 8.9 nM respectively. The elicitor-binding sites from both plants are stable during solubilization with non-ionic alkylglycoside detergents. However, differences are observed in the abundance of the binding sites and their selectivity towards structurally related analogues of the hepta-β-glucoside elicitor. Our results suggest that similar, but perhaps not identical, binding sites for the hepta-β-glucoside elicitor exist in diverse legumes, but not in plants outside of the legume family.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Plant molecular biology 26 (1994), S. 1379-1411 
    ISSN: 1573-5028
    Keywords: elicitors ; oligosaccharins ; phytoalexin synthesis ; phytoalexin accumulation ; signal transduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Child psychiatry & human development 22 (1991), S. 79-87 
    ISSN: 1573-3327
    Keywords: Hyperactivity ; psychostimulant medication ; attention deficit ; Stroop effect ; Wisconsin Card Sorting Test
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Hyperactive and normal children were given a test of selective attention (Stroop test) and a neurocognitive test sensitive to a functional deficit of prefrontal cortex (Wisconsin Card Sorting Test). Hyperactive children showed significant deficits on both measures. After a year of psychostimulant medication, the hyperactive children all showed clinical and neurocognitive improvement, but continued to show a selective attention deficit compared with normal children. The results indicate a dissociation between the cognitive processes measured by the Wisconsin test and selective attention as measured by the Stroop, and that the selective attention deficit is more resistant to psychostimulant intervention.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 30 (1987), S. 74-80 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A research project was initiated to examine the possibility of using supercritical carbon dioxide for in situ recovery of ethanol during its production by yeast Saccharomyces cerevisiae. As a preliminary step, it was necessary to study the behavior of ethanol production under high-pressure conditions, up to 7 MPa (1000 psi). The results show that pressure has a significant inhibiting effect on the production of ethanol. There is a significant decrease in the initial rate of production as well as in the final ethanol concentration as pressure is increased. This decrease is more significant when carbon dioxide is used to pressurize the fermentor. The pressure affects the ability of the cells to produce ethanol in a reversible way. When the fermentor is returned to atmospheric conditions, the reaction resumes its normal fermentation rate.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: β-1,3-Glucanase (laminarinase) activity was detected after polyacrylamide gel electrophoresis under native conditions by using laminarin as substrate. Following incubation of gels, laminarin was stained with Aniline Blue. Under UV illumination, lysis zones appeared as dark bands against a fluorescent background. As low as 0.001 unit of commercial Penicillium laminarinase could be observed after incubating the polyacrylamide gel for 45 min at pH 5.0. Extracts of commercial Penicillium laminarinase exhibited four bands with lytic activity towards laminarin. Analysis of intercellular fluid extracts of tobacco mosaic virus-infected tobacco leaves revealed four β-1,3-glucanases corresponding to three acidic pathogenesis-related proteins, b4 (2), b5 (N) and b6b (0), and one basic protein. The presence of laminarin in gels retarded the migration of some proteins with β1, 3-glucanase activity. This change in electrophoretic mobility could be used as a complementary affinity test for identifying proteins with β-1,3-glucanase activity.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: β-Glucanases were detected after polyacrylamide gel electrophoresis under native and denaturing conditions using various β-1, 3- and β-1, 4-glucans, including mixed glucans (laminarin, pachyman, carboxymethyl cellulose, lichenan and barley β-glucan). After electrophoresis and incubation of gels, substrates incorporated into polyacrylamide gels were stained with specific fluorochromes, Sirofluor for β-1, 3 linkages and Calcofluor White M2R for β-1, 4 linkages. Under UV illumination, lysis zones appeared as dark bands against a fluorescent background. Enzymes of bacterial, fungal and plant sources could be revealed sequentially in gles containing mixed β-(1.3) (1,4)-glucans by staining first with sirofluor followed by staining with Calcofluor White M2R. Active profiles were more diverse when substrates were stained with sirofluor. The use of purified sirofluor at pH 11.5 compared with Aniline Blue at pH 8.6 allowed better detection of β-1, 3-glucanase activities. In gels containing laminarin stained with sirofluor, bands exhibiting a more intense fluorescence than the background fluorescence were observed in addition to dark nonfluorescent bands. It is postulated that these two types of β-1, 3-glucanase activities differ by their enzymatic action (partial versus extensive hydrolysis). Analysis of fungal extracts using denaturing gels embedded with various β-glucans displayed lysis bands migrating between 32 and 35 kDa.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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