Degradation of transplanted mitochondrial proteins by hepatocyte monolayers.

Reductively [3H]methylated rat mitochondria and mitochondrial-outer-membrane vesicles and mitochondrial-outer-membrane vesicles where monoamine oxidase is irreversibly labelled by [3H]pargyline have been transplanted into hepatocytes by poly(ethylene glycol)-mediated organelle or organelle-vesicle cell fusion. During subsequent culture of hepatocyte monolayers for 4-5 days, under conditions which mimic endogenous catabolic rates in vivo the transplanted organelle proteins retain their degradation characteristics observed in vivo (e.g. mitochondria: average t 1/2 72.5 h; monoamine oxidase: t1/2 55 h). In all cases protein degradation with first-order kinetics is only observed after an initial lag period (i.e. 24-30 h after fusion). Transplantation of fluorescein-conjugated organelles showed that the fluorescent material is rapidly internalized (average t1/2 1-6 h) and uniformly distributed in the cytoplasm. During a subsequent 18-24 h period (which corresponds to the lag period for intracellular destruction of transplanted mitochondrial material) the transplanted material is translocated to assume a perinuclear distribution. The destruction of transplanted mitochondrial proteins is compared with endogenous mitoribosomally synthesized proteins (average t1/2 52.5 h). Percoll fractionation of cell homogenates containing transplanted mitochondrial outer membranes where the enzyme monoamine oxidase is irreversibly labelled with [3H]pargyline shows a distribution of enzyme similar to lysosomal acid phosphatase. After transplantation of reductively methylated 3H-labelled mitochondrial-outer-membrane vesicles the cells were treated with leupeptin to alter lysosomal density. This treatment leads to the predominant association of acid phosphatase with dense structures, whereas the 3H-labelled transplanted material predominantly does not change density. Therefore transplanted mitochondrial-outer-membrane proteins are found in intracellular vesicular structures from which the proteins are donated for destruction, at least in part, by a lysosomal mechanism.     

Studies on dissimilatory sulfate-reducing bacteria that decompose fatty acids

Gliding motility, ultrastructure and nutrition of two newly isolated filamentous sulfate-reducing bacteria, strains 5ac10 and 4be13, were investigated. The filaments were always attached to surfaces. Growth was supported by addition of insoluble aluminium phosphate or agar as substrata for gliding movement. Electron microscopy of ultrathin sections revealed cell walls characteristic of Gramnegative bacteria; the undulated structure of the outer membrane may pertain to the translocation mechanism. Intracytoplasmic membranes were present. Acetate, higher fatty acids, succinate or fumarate served as electron donors and carbon sources. Strain 5ac10 grew also with lactate, but not with benzoate that was used only by strain 4be13. Strain 5ac10 was able to grow slowly on H₂ plus CO₂ or formate in the presence of sulfate without additional organic carbon source. The capacity of complete oxidation was shown by stoichiometric measurements with acetate plus sulfate. Both strains contained b- and c-type cytochromes. Desulfoviridin was detected only in strain 5ac10. The two filamentous gliding sulfate reducers are described as new species of a new genus, Desulfonema limicola and Desulfonema magnum.     

Persistent ultrastructural changes in pancreatic acinar cells induced by 4-acetylaminofluorene

Male Leeds rats were fed a diet containing 0.05% of the non-carcinogen 4-acetylaminofluorene (4-AAF) for 8–10 months. They were then returned to a normal diet and their pancreatic tissues examined by electron microscopy at intervals between 2 and 12 months after the end of 4-AAF treatment. 4-AAF was found to induce a persistent alteration in the morphology of the granular endoplasmic reticulum, involving distortion and dilatation of the cisternae. In some respects this lesion resembles that which is induced by the carcinogenic isomer, 2-acetylaminofluorene (2-AAF).     

Dielectric properties of hemoglobin and myoglobin. I. Influence of solvent and particle size on the dielectric dispersion

Dielectric dispersion measurements with aqueous solutions of hemoglobin and myoglobin have been performed in the frequency range from 100 kcps to 15 Mcps. The influence of preparation, particle size, and solvent conditions was studied. The results are analyzed in terms of an orientational polarization mechanism.     

Die Fimbrien von Rhizobium lupini 1/50, sta-

Zusammenfassung Die Fimbrien (oder Pili) einer nicht sternbildenden Mutante (1–50, sta^-) von Rhizobium lupini wurden elektronenmikroskopisch untersucht. Die Fimbien sind peritrich an der Bakterienzelle inseriert, und zwar während der exponentiellen Wachstumsphase meist einzeln. In der stationären Phase nehmen die Fimbrien an Zahl und Länge kontinuierlich stark zu; sie sind dann häufig büschelweise inseriert. Zusammen mit den oft zopfbildenden Geißeln verflechten sie sich zu einem ausgedehnten Netzwerk. Die Aneinanderlagerung der Fimbrien erfolgt unspezifisch durch Kohäsion; durch ebenfalls unspezifische Adhäsion haften sie auf dem Substrat.Die Fimbrien haben ca. 30 Å Durchmesser und sind röhrenförmig gebaut. Ihre lichte Weite beträgt 8 bis 10 Å. Ein allgemeines Bauschema der Fimbrien wird diskutiert. In der Diskussion über die allgemeine Funktion aller Arten von Fimbrien wird ihre Haftfähigkeit herausgestellt. Die Fimbrien der Mutante 1/50, sta^- sind wegen ihres geringen Innendurchmessers nicht als Transportröhren für doppelsträngige DNS und wahrscheinlich auch nicht für einzelsträngige DNS oder RNS geeignet.

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The fimbriae of Rhizobium lupini 1/50, sta^-

Summary The fimbriae (pili) of a non-starforming mutant (1/50, sta^-) of Rhizobium lupini were studied under the electron microscope. In the exponential phase of growth, fimbriae are singly, peritrichously inserted. During stationary growth these fimbriae increase by number and length. Together with the larger flagella they often form an extended reticulum. The fimbriae often stick together by unspecific cohesion forces; their attachment to the substrate can be explained by unspecific adhesion.The outer diameter of the fimbriae is 30 Å, the inner diameter 8 to 10 Å.The tubelike structure of fimbriae (pili) is discussed in terms of a general model.The most obvious general function of all types of fimbriae is their connecting power.The inner dimension of the fimbriae of the 1/50, sta^-—mutant exclude a model where they function as transport tubes for double-stranded DNA and probably for single stranded DNA or RNA either.

     

Zur Kenntnis der GattungGentianella Moench in Jugoslawien. I. DerG. anisodonta-Komplex

Zusammenfassung Aus der subalpinen Stufe des nordwestlichen illyrischen Gebietes (Notranjski Snenik, nördlicher Velebit) wird als neue ArtGentianella liburnica E.Mayer et H.Kunz beschrieben, die im Bereiche der kleinblütigen Sippen desG. anisodonta-Komplexes einen morphologisch und chorologisch gut gekennzeichneten Südost-Vikaristen derG. engadinensis (Wettst.)Holub darstellt.Herrn Professor Dr.Lothar Geitler zum 70. Geburtstag gewidmet.