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  • 1
    Electronic Resource
    Electronic Resource
    Disturbed nitrogen metabolism associated with the hyperhydric status of fully habituated callus of sugarbeet (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 88 (1993), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The content of polyamines and proline was much lower in a normal (N) callus of Beta vulgaris L. than in a fully habituated hyperhydric (H) callus. The H callus also contained more glutamate and had a higher glutamate dehydrogenase activity. The excess of glutamate, in this chlorophyll-deficient callus, was linked to accumulation of proline and polyamines. Experiments with α-difluoromethylornithine (DFMO) and α-difluoromethylarginine (DFMA) showed that both ornithine decarboxylase and arginine decarboxylase participated in the synthesis of polyamines (especially spermidine and putrescine) and removal of ammonia. It is hypothesized that the H callus was subjected to ammonia stress from the start of the culture. Experiments with gabaculine, an inhibitor of ornithine aminotransferase, showed that this enzyme linked proline degradation to polyamine synthesis through the production of ornithine. This disturbed nitrogen metabolism appeared to be characteristic of the fully habituated callus and might explain the low growth of this hyperhydric tissue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1993.tb01770.x
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  • 2
    Electronic Resource
    Electronic Resource
    Ascorbate-glutathione cycle and H2O2 detoxification in elongating leaf bases of ryegrass: effect of inhibition of glutathione reductase activity on foliar regrowth (2002)
    Oxford, UK : Munksgaard International Publishers
    Physiologia plantarum 116 (2002), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The role of the ascorbate-glutathione cycle and AOS detoxification was investigated during leaf growth of defoliated and undefoliated plants of ryegrass (Lolium perenne L. cv. Bravo). Antioxidants and related enzymatic activities were located in elongating leaf bases (ELBs) of undefoliated plants, following a decreasing gradient from basal (meristem) to distal segments, inverse to H2O2 levels. In the meristematic zone, the intense activity of the ascorbate-glutathione cycle and the supply of reducing power by the oxidative pentose phosphate pathway allowed the maintenance of both antioxidant reduction and H2O2 detoxification. BCNU (1–3 bis(2-chloroethyl)-N-nitrosourea), a glutathione reductase inhibitor, induced an increase in the meristematic zone in both H2O2 and antioxidant levels and a decrease in reduced/oxidized ratios of glutathione and ascorbate. These changes were associated with a reduced foliar regrowth activity. In the absence of BCNU, defoliation did not modify the ratios of reduced/oxidized antioxidants, although it triggered a temporary increase in H2O2 level. The results are discussed on the basis of a possible control of leaf growth by glutathione and ascorbate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2002.1160317.x
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  • 3
    Electronic Resource
    Electronic Resource
    Stimulation par la lumière rouge lointain de la synthèse de la δ-aminolévulinate déshydratase des cotylédons de radis (1984)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 61 (1984), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Stimulation of de novo synthesis of δ-aminolevulinate dehydralasc of radishes grown under far-red light.Density labelling studies of δ-aminolevulinate dehydratase (ALAD) in cotyledons of radish (Raphanus sativus L. cv. Longue Rave Saumonée) seedlings demonstrate that far-red light stimulates de novo synthesis of ALAD and that the turn-over of this enzyme is very poor. Cycloheximide reduces considerably both the increase of ALAD activity and the incorporation of deuterium in ALAD, which indicates that ALAD synthesis depends upon cytoplasmic ribosomes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1984.tb06358.x
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  • 4
    Electronic Resource
    Electronic Resource
    Does altered nitrogen metabolism and H2O2 accumulation explain the vitrified status of the fully habituated callus of Beta vulgaris (L.)? (1993)
    Springer
    Plant cell, tissue and organ culture 35 (1993), S. 69-74 
    Details
    ISSN: 1573-5044
    Keywords: cytokinin autonomy ; hemoproteins ; hexoses mono-phosphate pathway ; polyamines ; proline ; vitrification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The habituated callus is a vitrified tissue which has two main biochemical characteristics both leading to production of toxic forms of oxygen: first the blockage of the porphyrin pathway and a lack of H2O2 detoxifying enzymes (catalase and peroxidases); secondly a deviation of the nitrogen metabolism induced by NH3 accumulation. Ammonia detoxification is ensured by increased glutamate dehydrogenase activity and accumulation of both proline and polyamines. A putative linkage between proline synthesis and the HMP pathway, as proposed for animal proliferating tissues (Phang 1985), might explain a high purine biosynthesis and cytokinin autonomy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00043941
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  • 5
    Electronic Resource
    Electronic Resource
    Disturbed sugar metabolism in a fully habituated nonorganogenic callus of Beta vulgaris (L.) (1993)
    Springer
    Plant growth regulation 13 (1993), S. 257-261 
    Details
    ISSN: 1573-5087
    Keywords: Beta vulgaris ; glycolysis ; hexose monophosphate pathway ; sugarbeet ; sugar metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Habituated (H) nonorganogenic sugarbeet callus was found to exhibit a disturbed sugar metabolism. In contrast to cells from normal (N) callus, H cells accumulate glucose and fructose and show an abnormal high fructose/glucose ratio. Moreover, H cells which have decreased wall components, display lower glycolytic enzyme activities (hexose phosphate isomerase and phosphofructokinase) which is compensated by higher activities of the enzymes of the hexose monophosphate pathway (glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase). The disturbed sugar metabolism of the H callus is discussed in relation to a deficiency in H2O2 detoxifying systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00024846
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Senescence of leaf sheaths of ryegrass stubble: changes in enzyme activities related to H2O2 metabolism (2000)
    Springer
    Plant growth regulation 30 (2000), S. 71-77 
    Details
    ISSN: 1573-5087
    Keywords: antioxidants ; Lolium perenne ; oxalate oxidase ; reactive oxygen species ; stubble senescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Changes in the levels of reactive oxygen species (O2.-, H2O2), and of activities of enzymes involved in their detoxification were investigated during senescence of leaf sheaths of ryegrass stubble. The accumulation of H2O2 in the medium leaf sheaths coincided with a drop in the levels of total glutathione, of pyridine nucleotides and of activities of monodehydroascorbate reductase and dehydroascorbate reductase. Conversely, a paradoxical increase in the ascorbate/ascorbate plus dehydroascorbate ratio was observed, which appears to be inconsistent with H2O2 accumulation. Our results suggest that oxalate might be an essential source of H2O2 in senescent leaf sheaths, and that oxalate oxidase might be involved in the defence of foliar tissue against pathogens during the progress of senescence. Moreover, it is assumed that glucid catabolism of the ryegrass stubble might be a starting point of a metabolic drain leading to ascorbate, then to oxalate during the late phase of leaf sheath senescence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006308928018
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  • 7
    Electronic Resource
    Electronic Resource
    Production of monospecific antisera by immunization with precipitin line leads to misinterpretation of immunoblot (1988)
    Weinheim : Wiley-Blackwell
    Electrophoresis 9 (1988), S. 103-104 
    Details
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Immunoblotting displays an artifact in the preparation of monospecific antibodies from immunocomplexes cut out of line immunoelectrophoresis. Agarose induces the formation of antibodies towards a 68 K Da protein which is contained in commercial agarose.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150090209
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