A new sensitive radial diffusion method for microdetermination of α-amylase

A sensitive agarose diffusion method for the determination of α-amylase has been developed, using Reactone Red 2 B-amylopectin as the substrate. The logarithm of enzyme activity is linearly correlated with the diameters of the diffusion zones over a very extended range from 1 mU/ml to at least 1100 U/ml. The α-amylase activity in biological samples may be determined without dilution or pretreatment, and the test can be performed at any desired temperature between 4 and 45°C. The clear radial diffusion zones may be fixed, further enhancing the contrast to the bright red surrounding.     

NAB2, a corepressor of EGR-1, inhibits vascular endothelial growth factor-mediated gene induction and angiogenic responses of endothelial cells

In this study we have investigated the role of a specific corepressor of EGR-1, NAB2, to down-regulate vascular endothelial growth factor (VEGF)-induced gene expression in endothelial cells and to inhibit angiogenesis. Firstly, we show a reciprocal regulation of EGR-1 and NAB2 following VEGF treatment. During the initial phase EGR-1 is rapidly induced and NAB2 levels are down-regulated. This is followed by a reduction of EGR-1 and a concomitant increase of NAB2. Secondly, using the tissue factor gene as a readout for VEGF-induced and EGR-1-regulated gene expression we demonstrate that NAB2 can completely block VEGF-induced tissue factor reporter gene activity. Thirdly, by adenovirus-mediated expression we show that NAB2 inhibits up-regulation of tissue factor, VEGF receptor-1, and urokinase plasminogen activator mRNAs even when a combination of VEGF and bFGF is used for induction. In addition, NAB2 overexpression significantly reduced tubule and sprout formation in two different in vitro angiogenesis assays and largely prevented the invasion of cells and formation of vessel-like structures in the murine Matrigel model. These data suggest that NAB2 regulation represents a mechanism to guarantee transient EGR-1 activity following exposure of endothelial cells to VEGF and that NAB2 overexpression could be used to inhibit signals involved in the early phase of angiogenesis.     

Zum Vorkommen helixförmig angeordneter Ribosomen bei Rhodopseudomonas palustris

Zusammenfassung Es wird das Vorkommen von Polysomensäulen bei Rhodopseudomonas palustris beschrieben. An Hand der Daten ergab sich, daß diese Polysomen aus zwei helixförmig angeordneten Ribosomensträngen aufgebaut sind, die eine linksdrehende Schraube bilden. Der Querschnitt der Schraube zeigt hexagonale Anordnung der Ribosomen. Der Steigungswinkel der Helices beträgt 20⁰, der Gesamtdurchmesser der hexagonalen Polysomensäule beträgt 375 Å. Diese Polysomenart kommt lediglich in der begeißelten Polregion vor und ist dicht unter der Cytoplasmamembran lokalisiert. Die Polysomen stehen mit der Cytoplasmamembran in Kontakt. Ihre Längsachse läuft parallel zur Plasmamembran.

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The occurrence of helical arranged ribosomes of rhodopseudomonas palustris

Summary Helical arranged ribosomes were detected in the polar region of Rhodopseudomonas palustris cells. They are attached to the cytoplasmic membrane. The columnar polysomes are shaped of two helical strings of ribosomes, which are arranged around the axis of the screw. The vertical projection of the single ribosomes in one turn of the screw is a hexagon. The helices are left handed. The angle between the horizontal line and the ribosome chain in the helix is =20⁰. The diameter of the polyribosome column amounts to 375 Å.

     

Der Geißelapparat von Rhodopseudomonas palustris

Zusammenfassung Rhodopseudomonas palustris Stamm 11/1 wirft bei Änderung der Umweltsfaktoren seine subpolar inserierende Geißel ab. Dieser Vorgang erfolgt auch während niedrigtouriger Zentrifugation. Die im Zentrifugenüberstand strukturell vollkommen erhaltenen Geißeln werden durch differentielle Zentrifugation angereichert und gereinigt.Durch Behandlung der Geißeln mit Aqua bidest. oder durch Einfrieren (-15° C) und Auftauen der in Aqua bidest. oder 0,05 M Trispuffer (pH 7,4) suspendierten Geißeln dissoziieren die Geißelfilamente, während die Geißelhaken strukturell erhalten bleiben. Auf diesen Eigenschaften basiert die Isolationsmethode der Geißelhaken.Ammonsulfatfällungen in Suspensionen dissoziierter Geißeln führen zur Aussalzung der protein-(flagellin-)haltigen Komponenten (1. Aqua bidest. lösliches, feinflockiges Präcipitat; 2. Aqua bidest. unlösliches, grobflockiges Material), während nach Zentrifugation das nichtproteinhaltige Geißelscheidenmaterial im Überstand verbleibt.Die scheidenhaltigen Geißeln von Rhodopseudomonas palustris enthalten nur eine einzige Proteinkomponente, das Flagellin, aus dem die core-Untereinheiten bestehen.

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The flagellar apparatus of Rhodopseudomonas palustris IV. Isolation of the flagellum and its parts

Summary Rhodopseudomonas palustris, strain 11/1, loses its flagellum when the environment is changed, f.e. during low speed centrifugation. The flagella which are well preserved in their structure are found in the supernatant of such centrifugation. They can be purified by differential centrifugation.By treatment of the flagella with distilled water or by freezing (-15°C) and thawing the flagellar filament is decomposed into subunits, whereas the flagellar hook does not become desintegrated. By using this procedure the flagellar hooks have been isolated.The solubilized flagellar filament material was precipitated by treatment with ammonium sulfate. Two different flagellin containing fractions were obtained, one is a fine precipitate which is soluble in distilled water, the other one is an unsoluble flocky material. After spinning down the protein containing fractions the nonproteinous sheath material remains in the supernatant.There is only one protein fraction in the total sheathed flagellum. This protein is the flagellin component of the core subunits.

     

A new sensitive radial diffusion method for microdetermination of alpha-amylase

A rapid, convenient, and efficient hybridization method for the determination of virus-specific RNAs in Py virus-infected cells is described. The method involves carrying out the hybridization of viral RNAs present in the RNA isolated from infected cells directly on nitrocellulose filters carrying denatured, immobilized Py-DNA (15 μl RNA solution/25-mm² filter). Under optimal conditions quantitative hybridization of viral RNA sequences is obtained within 24 h. The efficiency of hybridization is increased significantly when RNA fragmented by alkali under carefully controlled conditions is used.     

Antioxidative effect of ursodeoxycholic acid in the liver of rats with oxidative stress caused by gamma-irradiation

We studied effects of ursodeoxycholic acid (UDCA) (10 and 100 mg/kg b.w.) on the free radical generation, lipid peroxidation and the antioxidant defense system in the liver of rats with oxidative stress caused by gamma-irradiation. Both doses of UDCA normalized the liver parameters enhanced by gamma-irradiation: the content of superoxide anion and carbonyl-containing products of lipid peroxidation (alkanals, alkenals, alkadienals and ketones), the superoxide dismutase activity and the chemiluminescence enhanced by luminol. Only the highest dose of UDCA (100 mg/kg b.w.) decreased the chemiluminescence enhanced by lucigenin in liver microsomes and the hydroxyalkenals content in the liver. UDCA prevented reduced glutathione depletion caused by gamma-irradiation, whereas glutathione-related enzyme activities did not change under the influence of both the UDCA doses as well as gamma-irradiation. Thus, the data obtained suggest that UDCA is a metabolite having the sufficiently effective antioxidant properties.     

ATPase and cytochrome oxidase activities at the polar organelle in swarm cells of Sphaerotilus natans: an ultrastructural study

The polar organelle of bacteria presumably is part of the flagellar apparatus. In order to characterize this structure, cytochemical studies on Sphaerotilus natans have been performed.Marked ATPase activity is associated with the inner boundary layer and central layer of this organelle. The spaces between the boundary layers and the central layer of the polar organelle which are traversed by fine fibrilles are positive for reactions with diaminobenzidine. This indicates cytochrome oxidase activity. S. natans possesses a ribbon-like, helically shaped polar organelle which is divided concomitantly with cell fission, possibly explaining inheritance of this structure and of the flagellar apparatus.Dedicated to Prof. G. Drews on occasion of his 60th birthday     

Untersuchungen zur Adsorption des Bacteriophagen Rp 1 an Rhodopseudomonas palustris 1 e 5

Zusammenfassung Adsorptionskinetiken mit verschiedenen Rhodopseudomonas palustris-Stämmen ergaben, daß Rp 1-Phagen nur an Stamm 1 e 5 adsorbieren. Als Adsorptionskonstante wurde ein Wert von K=3,8·10^-10 ml/min ermittelt. Während des Wachstums der Wirtsbakterien werden die Rp 1-Phagen nur in der Teilungsebene und an einem Zellpol adsorbiert. Die Phagen adsorbieren auch an den intracytoplasmatischen Membranen. Die Spezifität dieser Adsorption wird diskutiert.

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Investigations on the adsorption of the bacteriophage Rp1 to Rhodopseudomonas palustris 1 e 5

Summary The adsorption of the bacteriophage Rp 1 is restricted to cells of the strain 1 e 5 of Rhodopseudomonas palustris. The adsorption constant was found to be K=3.8·10^-10 ml/min. During the growth phase of the host bacterium Rp 1 is only adsorbed to one of the cell poles and the division plain of the cells. In addition, the phage is adsorbed to the intracytoplasmic membranes. The specifity of this adsorption is discussed.

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Abkürzungen pfu plaque forming units - Rps. Rhodopseudomonas - R. Rhodospirillum     

ATPase activity of the polar organelle demonstrated by cytochemical reaction in whole unstained cells of Rhodopseudomonas palustris

The polar organelle, a structure associated with the flaggelar apparatus of bacteria, has been demonstrated in whole unstained cells of the photosynthetic bacterium Rhodopseudomonas palustris. It is subpolarly located close to the surface of the bacterial cell and has a round or ellipsoidal shap. It shows a strong ATPase activity which enables its cytochemical electron microscopical visualization.