A new method for the reconstitution of the anion transport system of the human erythrocyte membrane

Summary The anion transport protein of the human erythrocyte membrane, band 3, was solubilized and purified in solutions of the non-ionic detergent Triton X-100. It was incorporated into spherical lipid bilayers by the following procedure: (1) Dry phosphatidylcholine was suspended in the protein solution. Octylglucopyranoside was added until the milky suspension became clear. (2) The sample was dialyzed overnight against detergentfree buffer. (3) Residual Triton X-100 was removed from the opalescent vesicle suspension by sucrose density gradient centrifugation and subsequent dialysis. Sulfate efflux from the vesicles was studied, under exchange conditions, using a filtration method. Three vesicle subpopulations could be distinguished by analyzing the time course of the efflux. One was nearly impermeable to sulfate, and efflux from another was due to leaks. The largest subpopulation, however, showed transport characteristics very similar to those of the anion transport system of the intact erythrocyte membrane: transport numbers (at 30°C) close to 20 sulfate molecules per band 3 and min, an activation energy of approx. 140 kJ/mol, a pH maximum at pH 6.2, saturation of the sulfate flux at sulfate concentrations around 100mm, inhibition of the flux by H₂DIDS and flufenamate (approx.K _l-values at 30°C: 0.1 and 0.7 m, respectively), and right-side-out orientation of the transport protein (as judged from the inhibition of sulfate efflux by up to 98% by externally added H₂DIDS). Thus, the system represents, for the first time, a reconstitution of all the major properties of the sulfate transport across the erythrocyte membrane.     

Effect of β-FNA on Opiate δ Receptor Binding

Abstract: (β-FNA, the β -fumaramate methyl ester of naltrexone, has been shown to antagonize irreversibly the actions of morphine on the guinea pig ileum and mouse vas deferens bioassays but does not affect the actions of δ-receptor ligands on the mouse vas deferens bioassay, suggesting that the compound does not irreversibly bind to the S receptor. In this paper we examine the effect of (β -FNA on the binding of the prototypic δ agonists, Leuenkephalin and d -Ala²- d -Leu⁵-enkephalin, its metabolically stable analogue, and show that treatment of membranes with β -FNA does lead to alterations in the in vitro properties of δ receptors.     

Structural and chemical characterization of S-layers of selected strains ofBacillus stearothermophilus andDesulfotomaculum nigrificans

The structures, amino acid- and neutral sugar compositions of the crystalline surface layers (S-layers) of four selected strains each ofBacillus stearothermophilus andDesulfotomaculum nigrificans were compared. Among the four strains of each species a remarkable diversity in the molecular weights of the S-layer subunits and in the geometry and constants of the S-layer lattices was apparent. The crystalline arrays included hexagonal (p6), square (p4) and oblique (p2) lattices. In vitro self-assembly of isolated S-layer subunits (or S-layer fragments) led to the formation of flat sheets or open-ended cylindrical assembly products. The amino acid composition of the S-layers exhibited great similarities and was predominantly acidic. With the exception of the S-layers of two strains ofB. stearothermophilus (where only traces of neutral sugars could be detected), all other S-layer proteins seemed to be glycosylated. Among these strains significant differences in the amount and composition of the glycan portions were found. Based on this diversity interesting questions may be asked about the biological significance of the carbohydrate units of glycoproteins in prokaryotic organisms.     

Computer-aided three-dimensional reconstructions of the arrangement of primary spermatocytes in human seminiferous tubules

Summary With the use of a digital image-processing method three-dimensional reconstructions of the arrangement of spermatocytes in human seminiferous tubules were performed. With this method it was possible to investigate the cellular distribution in the tubule in nearly any given perspective and projection. In addition, by means of simple mathematical procedures, such as by transformation of Cartesian coordinates into cylindrical coordinates, it was possible to vary the shape of a reconstruction, i.e., to convert the cylindrical image of a tubular portion into a right-angled r--z-representation.The present work not only confirms the existence of a complex helical plan of organization of the human seminiferous epithelium but also provides further aspects of the phenomenon of physiological germ-cell loss and its integration into the kinetics of spermatogenesis.Dedicated to Prof. E.C. Roosen-Runge, Seattle, on the occasion of his 75th birthday     

Thermotoga maritima sp. nov. represents a new genus of unique extremely thermophilic eubacteria growing up to 90°C

A novel type of bacterium has been isolated from various geothermally heated locales on the sea floor. The organisms are strictly anaerobic, rod-shaped, fermentative, extremely thermophilic and grow between 55 and 90°C with an optimum of around 80°C. Cells show a unique sheath-like structure and monotrichous flagellation. By 16S rRNA sequencing they clearly belong to the eubacteria, although no close relationship to any known group could be detected. The majority of their lipids appear to be unique in structure among the eubacteria. Isolate MSB8 is described as Thermotoga maritima, representing the new genus Thermotoga.Dedicated to Otto Kandler on the occasion of his 65th birthday Present addresses: University of South Dakota, Vermillion, USA; University of Illinois, Urbana, USA; Universität für Bodenkultur, Wien, Austria     

Licht- und elektronenmikroskopische untersuchungen zur haftborstenentwicklung bei Tarentola m. mauritanica L. (Reptilia,Gekkonidae)

Zusammenfassung Kurz nach einer Hdutung wird bei Tarentola m. m. bereits die übemächste Epidermisgeneration — und somit auch die der Haftborsten —angelegt. Das geschieht vornehmlich in der Oz- (Oberhäutchenzellen-) und in der Hs-Schicht (clear layer). Zunächst entstehen die Aufspaltungen der Haftborstenenden, indem Keratinfilamentbündel nach einem bestimmten System von den Oz-Zellen aus in die Hs-Zellen einwachsen. Auf these Weise fungieren die Zellen der Hs-Schicht als Matrix der Haftborsten. Nach Abschluß dieses Prozesses werden die eigentlichen Haftborsten gebildet unter gleichzeitigem Auseinanderrücken der Hs- und Oz-Schichten. Die Hs-Schicht behdlt ihre Matrizen-Funktion bis zur anschließenden Häutung bei.

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Light and electron microscope studies of developing setae of Tarentola m. mauritanica (Rept., Gekkonidae)

Summary In Tarentola m. mauritanica the next epidermis generation but one and therefore the adhesive setae of the generation after this begin to develop shortly after a skin has been shed. This development takes place principally in the horny layer (Oz) and the clear layer. First bundles of keratin filaments radiate from the horny layer into the clear layer, thus giving rise to the split distal parts of the adhesive bristles. Thus the cells in the clear layer act as a matrix for the setae. When this stage is complete the formation of the setae proper begins, while the horny layer and the clear layer become separated from each other. The clear layer retains its function as matrix for the setae until the next time a skin is shed.

     

Gefrierätzung verschiedener Stämme von Bacillus sphaericus

Zusammenfassung Drei thermophile und ein mesophiler Bacillus sphaericus-Stamm wurden gefriergeätzt und ihre Feinstruktur verglichen. Mit Ausnahme eines thermophilen Stammes konnte bei allen untersuchten Organismen eine aus 13 nm großen Einheiten aufgebaute, rechtwinkelig geordnete Zellwandoberflächenstruktur nachgewiesen werden. Die Zellwand ließ sich bei sämtlichen Stämmen zweischichtig aufspalten. An ihren Querbrüchen traten 10–20 nm dicke Fibrillen auf, die als Subeinheiten der Zellwand gedeutet werden. Das Gefrierätzbild der Cytoplasmamembran läßt eine Deutung im Sinne einer teilweisen Aufspaltung längs einer zentralen Ebene zu.An aufgebrochenen Reservestoffgranula wurden hornartige Artefakte dargestellt, deren Entstehung teilweise auf eine schlagartige Expansion eines komprimierten, streng abgrenzbaren zentralen Teiles zurückgeführt wird.

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Freeze etching of different strains of Bacillus sphaericus

Summary The fine structures of three thermophilic and one mesophilic strain of Bacillus sphaericus have been compared by means of freeze etching. With the exception of one thermophilic strain, all strains had a rectangular cell wall surface structure consisting of 13 nm units. With all strains it was possible to split the cell wall into two layers. On its cross fractures 10–20 nm thick fibrils could be observed, presumably subunits of the cell wall.The image yielded by the freeze etched cytoplasmic membrane can be interpreted as due to partial cleaving along a central plane. The formation of hornlike artefacts rising from cross-fractured storage granules is explained partially by a sudden expansion of a compressed central part.