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  • 1
    Electronic Resource
    Electronic Resource
    Regulation and Glucocorticoid-Independent Induction of Lipocortin I in Cultured Astrocytes (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 57 (1991), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Stimulation of prostaglandin (PG) release in rat astroglial cultures by various substances, including phorbol esters, melittin, or extracellular ATP, has been reported recently. It is shown here that glucocorticoids (GCs) reduced both basal and stimulated PGD2 release. Hydrocortisone, however, did not inhibit ATP-, calcium ionophore A23187-, or tetradecanoyl phorbol acetate (TPA)-stimulated arachidonic acid release, and only TPA stimulations were affected by dexamethasone. GC-mediated inhibition of PGD2 release thus appeared to exclude regulation at the phospholipase A2(PLA2) level. Therefore, the effects of GCs on the synthesis of lipocortin I (LC I), a potent, physiological inhibitor of PLA2, were studied in more detail. Dexamethasone was not able to enhance de novo synthesis of LC I in freshly seeded cultures and failed to increase LC I synthesis in 2–3-week-old cultures. It is surprising that LC I was the major LC synthesized in those cultures, and marked amounts accumulated with culture time, reaching plateau levels at approximately day 10. In contrast, LC I was barely detectable in vivo. This tonic inhibition of PLA2 is the most likely explanation for unsuccessful attempts to evoke PG release in astrocyte cultures by various physiological stimuli. GC receptor antagonists (progesterone and RU 38486) given throughout culture time reduced LC I accumulation and simultaneously increased PGD2 release. Nonetheless, a substantial production of LC I persisted in the presence of antagonists. Therefore, LC I induction did not seem to involve GC receptor activation. This was confirmed in serum-and GC-free brain cell aggregate cultures. Here also a marked accumulation of LC I was observed. The data raise the hypothesis that enriched astrocyte cultures synthesize steroid-like compounds (neurosteroids).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1991.tb02113.x
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  • 2
    Electronic Resource
    Electronic Resource
    Calmodulin and calmodulin-mediated processes in plants (1984)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 7 (1984), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. The Ca2+ -binding protein calmodulin is found in all plants investigated so far. The comparison of the biochemical and functional properties reveals that it is structurally conserved and functionally preserved throughout the plant and animal kingdom. Among the plant enzymes so far known to be dependent on the Ca2+ -calmodulin complex are NAD kinase(s), Ca2+ -transport ATPase, quinate: NAD+ oxidoreductase, soluble and membrane bound protein kinases, and H+ -transport ATPase. Calmodulin may play also an important role in the regulation of other cellular reactions, such as hormone-mediated processes, secretion of enzymes, and contractile mechanisms. On the basis of the NAD kinase and its regulation by light and Ca2+ -calmodulin, it is suggested that changes in the cellular, free Ca2+ concentration following stimulation may alter the metabolism of a plant cell. According to this suggestion free Ca2+ may act as a second messenger in plants much as it does in animal cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1984.tb01426.x
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  • 3
    Electronic Resource
    Electronic Resource
    CALMODULIN-ACTIVATED PLANT MICROSOMAL Ca2+ UPTAKE AND PURIFICATION OF PLANT NAD KINASE AND OTHER PROTEINS BY CALMODULIN-SEPHAROSE CHROMATOGRAPHY (1980)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 356 (1980), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1980.tb29632.x
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  • 4
    Electronic Resource
    Electronic Resource
    Identification of calmodulin in the green alga Mougeotia and its possible function in chloroplast reorientational movement (1984)
    Springer
    Planta 162 (1984), S. 62-67 
    Details
    ISSN: 1432-2048
    Keywords: Calcium (chloroplast movement) ; Calmodulin (chloroplast movement) ; Chloroplast movement (Mougeotia) ; Mougeotia ; Phytochrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A soluble protein was isolated from Mougeotia by chloropromazine-sepharose 4 B affinity chromatography. The protein matches the properties of calmodulin in terms of heat stability, Ca2+-dependent electrophoretic mobility in sodium-dodecyl-sulfate polyacrylamide gels, and its ability to activate cyclic nucleotide phosphodiesterase in a Ca2+-dependent manner. Phytochrome-mediated chloroplast reorientational movement in Mougeotia was inhibited by the calmodulin antagonist trifluoperazine, a hydrophobic compound, or N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7), a hydrophilic compound; 50% inhibition (IC50) of chloroplast movement is caused by 20–50 μmol l-1 trifluoperazine or 100 μmol l-1 W-7. The Ca2+-calmodulin may act as an intermediate in the chloroplast reorientational response in Mougeotia governed by phytochrome.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397422
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  • 5
    Electronic Resource
    Electronic Resource
    Calmodulin-dependent and independent NAD kinase activities from cytoplasmic and chloroplastic fractions of spinach (Spinacia oleracea L.) (1982)
    Springer
    Plant cell reports 1 (1982), S. 119-122 
    Details
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract NAD kinase activity has been found in a soluble, cytoplasmic fraction and in the chloroplasts prepared from green spinach leaves. A small amount of both the cytoplasmic and the chloroplastic NAD kinase activities was retained on a calmodulin-Sepharose affinity column. The cytoplasmic NAD kinase eluted from the affinity column was found to be enhanced by calmodulin in a Ca2+-dependent manner. The chloroplastic enzyme which is located exclusively in the stroma and not in the envelope and thylakoid fractions was not affected by Ca2+ and calmodulin. The stromal fraction of purified chloroplasts contained only a negligible amount of calmodulin, most probably due to cytoplasmic contamination. Based on these data, two different mechanisms for the light-dependent modulation of spinach NAD kinase activity are suggested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00272368
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  • 6
    Electronic Resource
    Electronic Resource
    Ca2+ transport in mitochondrial and microsomal fractions from higher plants (1980)
    Springer
    Planta 150 (1980), S. 1-8 
    Details
    ISSN: 1432-2048
    Keywords: Calcium uptake ; Microsomes ; Mitochondria ; Transport (Ca2+) ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mitochondria from etiolated corn possess a much greater Ca2+ uptake capacity per mg protein than microsomes from the same source. Differences in energy requirements, sensitivity to specific inhibitors, and sedimentation properties enabled us to study both Ca2+ uptake mechanisms without mutual contamination. The microsomal Ca2+ uptake does not vary much among different plants as compared to the mitochondrial Ca2+ uptake; this is also true for different organs of the same plant. Mitochondrial Ca2+ uptake is more dependent on the age of the seedlings than microsomal uptake, because of changes in active Ca2+ uptake activity rather than of changes in efflux. Intactness and the oxidative and phosphorylative properties of the mitochondria remained unchanged during this time period. Na+ and Mg2+ do not induce Ca2+ release from mitochondria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00385606
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  • 7
    Electronic Resource
    Electronic Resource
    The effect of calmodulin and far-red light on the kinetic properties of the mitochondrial and microsomal calcium-ion transport system from corn (1983)
    Springer
    Planta 159 (1983), S. 277-281 
    Details
    ISSN: 1432-2048
    Keywords: Calcium uptake ; Calmodulin ; Light, far-red ; Microsome ; Mitochondrion ; Zea (calcium transport)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The kinetic properties of active Ca2+ transport into mitochondria and microsomal membrane vesicles prepared from coleoptiles of dark-and light-grown corn seedlings have been studied. The apparent values for K m and V max for Ca2+ of the mitochondrial transport system from dark-grown plants are about one order of magnitude higher than those from the microsomal transport system. Calmodulin has no effect on the Ca2+ accumulation into mitochondria whereas the apparent maximum transport velocity and affinity for Ca2+ of the microsomal Ca2+-transport system are both increased by calmodulin. When intact corn seedlings are irradiated with far-red light, the calmodulin-induced increase of the apparent maximum transport velocity and affinity for Ca2+ can no longer be observed. From these data it can be concluded that the low cytoplasmic Ca2+ concentration in the cytoplasm of coleoptile cells from dark-grown corn is maintained by a calmodulin-regulated Ca2+ pump. Irradiation with photomorphogenically active far-red light lowers the Ca2+-transport activity and thus causes an increase of the cytoplasmic, free-Ca2+ concentration. The physiological implications will be discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397536
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  • 8
    Electronic Resource
    Electronic Resource
    Molekülverbindungen der Pyrrole und Pyrrolfarbstoffe (1934)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 513 (1934), S. 65-93 
    Details
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.19345130105
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  • 9
    Electronic Resource
    Electronic Resource
    Protein kinase C involved in zymosan-induced release of arachidonic acid and superoxide but not in calcium ionophore-elicited arachidonic acid release or formation of prostaglandin E2 from added arachidonate (1992)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 48 (1992), S. 288-295 
    Details
    ISSN: 0730-2312
    Keywords: macrophages ; phospholipase A2 ; NADPH oxidase ; prostaglandins ; staurosporine ; phorbol ester ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Zymosan and phorbol ester induced in liver macrophages the release of arachidonic acid, prostaglandin E2, and superoxide; the calcium ionophore A 23187 elicited a release of arachidonic acid and prostaglandin E2 but not of superoxide, and exogenously added arachidonic acid led to the formation of prostaglandin E2 only. The zymosan- and phorbol-ester-induced release of arachidonic acid, prostaglandin E2, and superoxide was dose-dependently inhibited by staurosporine and K252a, two inhibitors of protein kinase C, and by pretreatment of the cells with phorbol ester which desensitized protein kinase C. The release of arachidonic acid or prostaglandin E2 following the addition of A 23187 or arachidonic acid was not affected by these treatments. Zymosan and phorbol ester but not A 23187 or arachidonic acid induced a translocation of protein kinase C from the cytosol to membranes in intact cells. These results demonstrate an involvement of protein kinase C in the zymosan- and phorbol-ester-induced release of arachidonic acid, prostaglandin E2, and superoxide; the release of arachidonic acid and prostaglandin E2 elicited by A 23187 and the formation of prostaglandin E2 from exogenously added arachidonic acid, however, is independent of an activation of protein kinase C.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240480309
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