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  • Frankia  (4)
  • General Chemistry  (3)
  • Rat  (2)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 93 (1993), S. 279-287 
    ISSN: 1432-1106
    Schlagwort(e): Valproate ; Anticonvulsant ; Sodium inactivation ; Patch clamp ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Cultured rat hippocampal neurons with short processes were investigated using the whole cell voltage clamp under conditions appropriate for isolating Na+ currents. After incubation of the neuron culture for a period of 15–30 min in 1 mM sodium valproate, several parameters of the Na+ current were changed. The peak Na+ conductance g p, measured using hyperpolarizing prepulses, was reduced by valproate in a voltage-dependent manner. In the membrane voltage range from -30 to +20 mV, this reduction showed a linear dependence on voltage, increasing from about zero to approximately 30% of g p, the maximum peak Na+ conductance of the neuron. At the holding voltage of -70 mV, the inactivation parameter h t8 decreased from 0.88 in the control to 0.64 in the valproate solution. This reduction originated mainly from a 10 mV shift in the sigmoid relation between h t8 and membrane voltage along the voltage axis to hyperpolarizing potentials. The decay of the maximum peak Na+ current (inactivation) could be fitted by a biexponential function. Time constants of the fast and slow component at -20 mV decreased in valproate by about 50%. Valproate also retarded the recovery from inactivation, as determined at the holding voltage. The sigmoid recovery from inactivation could reasonably be described by an exponential function with time constant τ r and delay time Δt. Both τ r and At increased more than 200% in valproate. Our results indicate that valproate affected the Na+ current in hippocampal neurons in a way that contributed to a considerable depression of Na+ reactivation. This explains the frequency-dependent inhibition of action potentials as observed in mammalian central nervous tissue and may be the principal action of the anticonvulsant.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Pflügers Archiv 385 (1980), S. 211-215 
    ISSN: 1432-2013
    Schlagwort(e): Rat ; Renal hypertension ; Plasma renin activity ; Water intake ; Declipping ; Reclipping ; Converting enzyme inhibitor
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Application of a renal artery clip in rats with an undisturbed contralateral kidney caused a sustained increase in blood pressure and a transient rise of plasma renin activity and water intake. The response of blood pressure, plasma renin activity and water intake was augmented after reapplication of the clip to normotensive declipped rats (renal hypertensive rats, from which the clip had been removed 24 h before the reapplication). The time-course of the changes of blood pressure, plasma renin activity and water intake were similar after the initial application as after reapplication of the clip. Administration of an inhibitor (SQ 14.225) of the converting enzyme abolished the increase in blood pressure and water intake after reapplication of the clip. These data indicate a critical role of renin in the rise of blood pressure and water intake after initial application of a renal artery clip as well as after reapplication of the clip to declipped rats.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Protoplasma 159 (1990), S. 35-43 
    ISSN: 1615-6102
    Schlagwort(e): Actinorhizal capsule ; Cellulose ; Enzyme-gold cytochemistry ; Frankia ; Plant cell wall ; Xylans
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Enzyme-gold affinity labeling was used to show that in mature infected cells of actinorhizal symbioses the capsule on the plant host side of the symbiotic interface contained cellulose and xylans. Host species examined for cellulose wereAlnus rubra, Casuarina equisetifolia, C. glauca, Ceanothus cuneata, C. velutinus, Elaeagnus pungens, andMyrica cerifera.. Cellulose was in the capsule throughout the infected cell, implying that during development cellulose synthase was present in the host cell membrane component of the symbiotic interface. Any possible degradation of capsule cellulose by the microsymbiont was either incomplete or transient, because the polymer was present in mature infected cells. Cellulose labeling inCeanothus andElaeagnus was less consistent than in the other species. Dual labeled capsules inCasuarina glauca andAlnus rubra showed a similar distribution of xylans and cellulose. Cytochemical studies indicate that the capsule contains three major classes of cell wall polysaccharides: cellulose, hemicellulose (xylans), and pectins (shown previously). This suggests that the capsule is essentially a thin, internal, tubular plant cell wall.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Protoplasma 136 (1987), S. 104-117 
    ISSN: 1615-6102
    Schlagwort(e): Actinomycete ; Casuarina ; Development ; Frankia ; Root ; nodules ; Symbiosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary This is an ultrastructural study of development of infected cells in nitrogen fixing root nodules ofCasuarina spp. While several aspects of development are similar to those found in many other actinorhizae, unusual aspects of development of the host cell and differentiation of the endophyte inCasuarina are correlated with unusual changes in the wall of the infected cell. Instead of vesicles the endophyte forms atypical hyphae in mature infected cells. These unusual hyphal forms are termed intracellular hyphae. Intracellular hyphae are nonseptate hyphae which originate and terminate within the same host cell, and have a varying diameter and a multidirectional growth and branching pattern. A laminate surface layer previously undescribed on hyphae ofFrankia is a feature common to mostCasuarina endophytic hyphae and is probably similar chemically to the laminae comprising the multilamellate envelope of endophytic vesicles in other actinorhizae.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Protoplasma 183 (1994), S. 37-48 
    ISSN: 1615-6102
    Schlagwort(e): Actinomycete ; Frankia ; Procaryote cell wall ; Symbiosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Using tissue stained en bloc with chromic acid or tissue prepared by high pressure-freezing and freeze-substitution, it was possible to analyze quantitatively the ultrastructure of symbiotic vesicle envelopes (SVE) inAlnus serrulata, Ceanothus americanus, Elaeagnus umbellata, andMyrica cerifera. The lamina measured about 4.7 nm in thickness in thin section. Despite diverse symbiotic vesicle morphology, the SVE thickness was similar in all of these symbioses: 36–71 nm, which corresponded to 6–15 laminae based on counts of chromic acid-stained SVEs. This similarity in structure suggests that a similar environmental signal regulates envelope thickness in the different root nodules. Based on previous studies, this is likely to be pO2. Three types of envelope morphologies were distinguished: (1) theAlnus-type (as inAlnus andElaeagnus), which had localized thickenings around the vesicle and had thickest dimensions over the stalk; (2) theCeanothus-type. characterized as a relatively uniform envelope over both vesicle and attached hypha, and (3) theMyrica-type, which had no stalk region and a basal SVE thickness of about six laminae throughout except where localized thickening occurred. Localized thickening of the SVE resulted from extra numbers of laminae being deposited, generally over regions where septa contacted the edge of the vesicle. Freeze-substituted symbiotic vesicles had a variety of novel structures that are poorly preserved in chemically-fixed tissue. A paracrystalline body inAlnus symbiotic vesicles may be composed of particles that also exist free in the symbiotic vesicle cytoplasm. In addition, a previously unknown complex at the base of theAlnus-type symbiotic vesicle and within its stalk was evident in freeze-substituted tissues.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 118 (1989), S. 119-123 
    ISSN: 1573-5036
    Schlagwort(e): actinorhizal nodules ; Casuarina cunninghamiana ; Frankia ; nitrogen fixation ; oxygen
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The gas diffusion pathway in nodules was traced by vacuum infiltration with India ink or aniline blue and by electron microscopy. India ink infiltration was observed in the outermost and the innermost cortex in sliced nodules, but not in intact nodules. With aniline blue infiltration, it was observed that intercellular air spaces in the outermost and the innermost cortex were connected to those in nodule roots. No air spaces were in contact with walls of infected cells, although intercellular air spaces existed in some groups of uninfected cells within the infected zone. Infiltration with either India ink or aniline blue could not be observed in the infected zone in essentially all cases. Thus it is suggested that the discontinuity of the intercellular air spaces represents a major resistance to O2 diffusion in nodules ofCasuarina cunninghamiana.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 52 (1939), S. 670-670 
    ISSN: 0044-8249
    Schlagwort(e): Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    ISSN: 0044-8249
    Schlagwort(e): Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 48 (1935), S. 597-601 
    ISSN: 0044-8249
    Schlagwort(e): Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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