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  • 1
    ISSN: 1432-1017
    Keywords: Plant injury/stimulation Induced current/magnetic field SQUID magnetometer Injury-induced signal propagation Post-injury distribution of electrical activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract. A superconducting quantum interference device (SQUID) multichannel magnetometer was used to measure the temporal and spatial evolution of the magnetic field accompanying stimulation by burning and/or cutting of Vicia faba plants. These magnetic fields are caused by ionic currents that appear after injury in different parts of the plant. All measured V. faba plants responded to the burning stimulation with detectable quasi-d.c. magnetic signals. In order to measure these signals, a suitable modulation had to be used. The covariance method was applied to analyse the measured data. The results demonstrate a dipolar-like magnetic signal, exponentially decreasing in time, above the cutting type of injury. After the burning stimulation, the magnetically detected activity was concentrated predominantly above the leaves/petioles and less above the stem. Possible mechanisms for this behaviour are suggested. A comparison with previously known electrical measurements of plant injury is given.
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  • 2
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A direct measuring method for the determination of 15 inorganic components in wine by ICP-OES was developed. It was applied to 17 white wines from 6 German wine-growing regions. In these investigations 15 elements (B, V, Mn, Zn, Fe, Al, Cu, Sr, Ba, Rb, Na, P, Ca, Mg and K) were involved. By using alcoholic calibration solutions the results of the direct measuring method are comparable with those of the control methods. Typical patterns of elements obtained by the multicomponent analyses can be evaluated by multivariate data analysis to recognize the origin of the wines.
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  • 3
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Es wird ein einfacher Apparat beschrieben, der schnelles und gleichmässiges Waschen von adhärenten Zellen in Microtest II 3040 Platten (Falcon) erlaubt. Eine Gruppe von 12 zylindrischen Vertiefungen mit flachem Boden wird gleichzeitig behandelt. Der Apparat ist einerseits an Sog und anderseits an eine automatische Spritze mit verstellbarem Volumen (Cornwall) angeschlossen. Er fand ausgiebig Verwendung in einem in vitro Testsystem für direkte zellvermittelte Zytotoxizität. Als Zielzellen dienten51Cr markierte peritoneale Macrophagen.
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  • 4
    ISSN: 1420-9071
    Keywords: Acute ischemic renal failure ; angiotensin converting enzyme inhibition ; enalapril ; tubulo-glomerular feedback/proximal tubular pressure ; renal histology ; medullary capillary congestion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The influence of the renin-angiotensin system on renal hemodynamics, tubular pressure and tubulo-glomerular feedback was investigated with the angiotensin converting enzyme inhibitor MK 421 (enalapril), in uninephrectomized rats with and without ischemia-induced acute renal failure. In animals with normal renal function proximal tubular pressure and tubulo-glomerular feedback response were lowered by enalapril long-term treatment, whereas glomerular filtration rate and renal blood flow were not influenced by the drug. After 45 and 70 minutes ischemia there was no difference between treated and untreated animals in the severely impaired glomerular filtration rate. Renal blood flow remained unaffected by the treatment. The histological damage due to ischemia (tubular casts, tubular necrosis and medullary capillary congestion) was not influenced by enalapril. As tubulo-glomerular feedback had been significantly inhibited during renin-angiotensin inhibition, its importance in mediating acute renal failure remains doubtful; other factors such as tubular obstruction and medullary congestion may be crucial.
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  • 5
    ISSN: 1615-6102
    Keywords: Auxin ; Maize coleoptiles ; Membrane potential ; Cycloheximide ; Protein synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The contribution of protein synthesis and secretion to indol acetic acid (IAA) induced polarisation of the plasma membrane voltage (V M) was investigated. TheV M of coleoptiles fromZea mays was measured in the presence of known inhibitors of protein- and RNA synthesis, as well as those of Golgi-mediated vesicle secretion. Inhibitors were applied under conditions at which they are known to abolish IAA stimulated H+ secretion and cell elongation effectively. Cycloheximide (CHI), an inhibitor of protein synthesis, caused depolarisation ofV M with a half maximal concentration of approximately 20 μM. At 100 μM CHI,V M depolarised to a new stable voltage with a half time of 9.8 ± 0.6 min. The temporal similarity of CHI-induced depolarisation and cessation of coleoptile elongation suggests that the induced change inV M underlies inhibition of elongation. CHI evoked membrane depolarisation to a final voltage of about −100 mV irrespective of the presence or absence of auxin in the external medium. Thus, CHI probably affected constitutive membrane transport properties independently of IAA-induced modulation of transport proteins. Cordycepin (COR), an inhibitor of RNA synthesis, had no significant effect at 400 μM onV M of IAA-treated cells, suggesting that gene transcription for transport- or regulatory protein synthesis was not essential for IAA-generated polarisation ofV M. Brefeldin-A (BFA), an inhibitor of Golgi-mediated vesicle secretion in maize coleoptiles, had no perceivable effect at 20 mg/1 onV M of IAA-treated coleoptile cells, demonstrating that constitutive or IAA-stimulated protein secretion was not essential for the mechanism underlying IAA-evokedV M polarisation. Hence, IAA-stimulated and COR/BFA-depressed H+ extrusion in elongating coleoptiles may not be entirely mediated by auxin-enhanced ATPase activity.
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  • 6
    ISSN: 1615-6102
    Keywords: Zea mays ; Coleoptile ; Pectolyase ; Protoplast isolation ; Auxin ; Membrane potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Protoplasts are frequently isolated from maize coleoptiles with cell-wall-degrading enzymes such as pectolyase (PEC), mazerozyme, and cellulase. Incubation of coleoptiles with these enzymes caused rapid depolarizations of the membrane voltage (V M ). The depolarizing effect of 0.5% (w/v) mazerozyme or 1.5% (w/v) cellulase was unaffected by denaturation of the enzymes. In the case of pectolyase (0.1%, w/v), however, the active enzyme was significantly more potent than the denaturated enzyme in depolarizing coleoptile cells. Exposure to 0.1% active PEC but not to inactive PEC also caused an oxidative burst in coleoptiles and enhanced K+ efflux. Together this suggests that pectic breakdown products of the cell wall act as signal for wounding. Typically addition of 10 μM 1-naphthylene acetic acid (NAA) to coleoptiles causes a transient depolarization followed by a slow hyperpolarization of V M . However, in the presence of PEC, V M only depolarized in NAA. After PEC-treated coleoptiles were washed free of the enzyme, NAA caused only small fluctuations of V M . A similarly small V M response to NAA appeared in coleoptiles pretreated with heatdenaturated supernatant (SUP) from a protoplast isolation buffer, the latter suspected to contain the PEC-generated wounding signal. Comparable pretreatment of coleoptiles with PEC or SUP had no significant effect on the spontaneous and NAA-evoked acidification of the incubation medium. Pretreatment with SUP also had no significant effect on the NAA-stimulated elongation of coleoptile segment. Hence, PEC treatment of coleoptile tissue affects the membrane transport properties of the cells. This effect is partly maintained after removal of the enzyme from the incubation medium, an effect not significant for NAA-generated acidification and cell elongation.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 179 (1994), S. 26-33 
    ISSN: 1615-6102
    Keywords: Intracellular pH ; Light/dark ; Nitella ; Redox potentiometry ; Redox state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The present paper describes the construction and properties of a Pt/Ir-semi-microelectrode and its application as a redoxsensitive electrode in intact cells of the giant algaNitella. For compartmental analysis of the stationary redox-state voltage (ERED), a value reflecting the interaction of the dominant redox couples with a Pt/Ir-electrode, the redox-sensitive electrode was inserted into the vacuole of leaf cells or cytoplasm enriched fragments (CEF) fromNitella internodal cells. After correction for the membrane voltage, measured with a second, conventional voltage electrode, ERED values of+237±93mVand+419±51 mV with respect to a normal H+-electrode were obtained for cytoplasm and vacuole, respectively. The redox-state of the cell culture medium was+604 mV. The steady state ERED in the cytoplasm can be perturbed by experimental treatments: indirect acidification of the cytoplasm by an external pH jump from 7.5 to 5.8 and direct acidification, by acid loading with 5 mM butyrate, both resulted in a positive shift of ERED, i.e., to an increase in cytoplasmic oxidation. At the same time the membrane depolarized electrically following the external pH jump, but hyperpolarized in response to acid loading. The data demonstrate the direct dependence of cytoplasmic redox state on intracellular pH, probably due to enhanced oxidation of protonated redox couples favoured by mass action. The electrical membrane voltage changes were not correlated with the shift in cytoplasmic ERED. This demonstrated that redox energy does not determine the electrical membrane voltage. Cytoplasmic ERED was also affected by photosynthesis. When CEFs were transferred from light to dark, or exposed to 10μM 3-(3,4-dichlorophenyl)-1,l-dimethylurea (DCMU), ERED shifted negatively (more reduced) by 6.4±4.5mV or 4.2±2mV, respectively. These data compare favourably with biochemical estimates of cytoplasmic pyridin nucleotides which also show an increase in cytoplasmic reduction in the dark. Therefore, it is unlikely that diffusable reducing equivalents are supplied to the cytoplasm from photosynthetically-active chloroplasts to act as secondary messengers.
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  • 8
    ISSN: 0020-1693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
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  • 9
    ISSN: 0021-9614
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Ocean dynamics 6 (1953), S. 107-123 
    ISSN: 1616-7228
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Description / Table of Contents: Summary The relations between the weather situations over the North-Sea and the Baltic on the one hand and the sea level in the Baltic on the other hand are studied. Moreover, a method is developed allowing to ascertain the pressure distribution in any weather situation over the Baltic by way of mathematical calculation and to verify that the variations in sea level as compared to mean sea level in the Baltic depend on the respective air pressure distribution over the North-Sea and the Baltic. The variations in sea level in the Bay of Kiel as referred to mean sea level are represented as a function of the air-pressure distribution over the North-Sea and the Baltic. In conclusion, the application of the method to the great storm surge of November 13, 1872, in the Baltic and to the storm surge of September 23, 1924, in the Gulf of Finland clearly demonstrates its usefulness.
    Abstract: Résumé L'auteur étudie les rapports qui existent entre les situations du temps sur la mer du Nord et sur la Baltique d'une part et les niveaux de la mer dans la Baltique d'autre part. Il dévelope une méthode qui permet de déterminer au moyen des mathématiques la distribution de la pression atmosphérique d'un état quelconque du temps dans la région de la mer Baltique et de vérifier que les variations des niveaux de la mer par rapport au niveau moyen de la mer (N. M.) dans la mer Baltique dépendent de la distribution particulière de la pression sur la mer du Nord et de celle sur la Baltique. Les variations des niveaux de la mer en comparaison du niveau moyen dans la baie de Kiel sont représentées en fonction de la distribution de la pression sur la mer du Nord et sur la Baltique. Enfin, l'auteur démontre l'utilité pratique de cette méthode en l'appliquant à la très forte tempête du 13 novembre 1872 sur les côtes de la Baltique et à la tempête du 23 septembre 1924 dans le golfe de Finlande.
    Notes: Zusammenfassung Es werden die Beziehungen zwischen den Wetterlagen über dem Nord- und Ostseegebiet und den Wasserständen in der Ostsee behandelt und ein Verfahren entwickelt, daß es ermöglicht, die Luftdruckverteilung in einer Wetterlage über dem Ostseegebiet mathematisch zu erfassen, sowie die Abhängigkeit der Schwankungen der Wasserstände gegen Mittelwasser in der Ostsee von der jeweiligen Luftdruckverteilung über dem Nord- und Ostseegebiet nachzuweisen. Die Schwankungen des Wasserstandes gegen Mittelwasser in der Kieler Bucht werden als Funktion der Luftdruckverteilung über dem Nord- und Ostseegebiet dargestellt. Zuletzt wird die Verwendbarkeit des Verfahrens durch eingehende Anwendungen auf die große Ostseesturmflut vom 13. November 1872 und die Sturmflut im Finnischen Meerbusen vom 23. September 1924 gezeigt.
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