Topographical features of the membrane of Poterioochromonas malhamensis after colchicine and osmotic treatment

Changes in membrane topography in the flagellate Poterioochromonas malhamensis, as a result of colchicine and osmotic-stress treatments, have been studied using freeze-fracturing and thin sectioning. Ridges, but not rows of intramembrane particles, in the PF-face which denote the position of underlying cortical microtubules, together with the ridge associated with their point of origin (flagellar root fibre 1), dissappear after colchicine or short-term (5 min) osmotic treatments. Cortical microtubules are destroyed as a result of the former, but not the latter treatment. Longer periods in osmoticum allow a recovery of the microtubule — associated membrane ridges. Despite careful isosmotic fixations distinct cross-bridges between microtubules and the plasmalemma were not discernible in thin section.     

Supraoptimal growth-temperature reduces the heat-shock sensitivity of the chrysophycean flagellatePoterioochromonas malhamensis

Summary The chrysophycean flagellatePoterioochromonas malhamensis shows some characteristic alterations after a sublethal heat-shock (42 C, 16 minutes). Most cells round up and retract their cytoplasmic tail. The lorica formation is affected and, in nearly all cells, flagellar activity. Most membrane systems, especially the dictyosome, are severely damaged. In contrast the flagellar root apparatus and the cortical microtubules seem to be unaffected.After growth at a supraoptimal temperature of 33 C and a subsequent heat-shock (42 C, 16 minutes) the cells do not show the heat injuries reported above. The ability to form the lorica becomes also adapted to higher temperatures.Possible adaptation mechanisms are discussed.     

Zellteilung und Bildung von Innenschalen beiHantzschia amphioxys undAchnanthes coarctata

Before cytokinesis, the identically constructed chromatophores ofHantzschia amphioxys andAchnanthes coarctata are transformed into less effigurated bodies. In normal cytokinesis, the course of mitosis, chromatophore division, and cleavage furrowing are exactly synchronized. The division of the chromatophore appears as a passive process, i.e. intersection by the cleavage furrow. In inequal cell divisions before the formation of inner valves cytokinesis can take place without chromatophore division. Once chromatophore division without mitosis and cytokinesis was observed. InHantzschia there are three types of inner valve formation, inAchnanthes coarctata only two. The inner valves develop under unfavorable growth conditions, the cells possessing them, however, are not resting spores as in some other diatoms. InHantzschia, auxospore formation is suppressed under the cultural conditions used, the cells multiply intensely without diminution.

     

Destruction and reconstitution of the dictyosome in the chrysophycean flagellate,Poterioochromonas malhamensis,after heat-shock,and other heat-shock effects

Summary The viability of the chrysophycean flagellate,Poterioochromonas malhamensis, was examined after treatment of the cells with high temperatures. The fine structure of the cells was studied after heat-shock (42 °C, 16 minutes). Heat injury effects are visible at the nucleus, the chloroplast (distortion of the thylakoids), the mitochondria (increased occurrence of matrical crystalline inclusions) and, especially, at the dictyosome which is completely destroyed into some single vesicles and remnants of cisternae. Most damages are repaired within one hour; the reconstitution of the dictyosome takes 3–6 hours. It is inhibited severely by actinomycin D.The effect on the dictyosome reflects its labile position in the endomembrane system. The dependence of its reconstitution on protein synthesis indicates that membrane components are destroyed by the heat-shock.     

Verteilung und Aufteilung der DNS bei einigen Cyanophyceen,festgestellt durch ihre DAPI-Fluoreszenz

The DNA of Blue-Green Algae may be specifically and most efficiently elucidated by the combined use of the fluorochrome DAPI and DNAse treatment. InChroococcus turgidus andSynechococcus aeruginosus it forms a network which usually is positioned at the periphery of the centroplasm. At the beginning of cell division it seems to be invaginated by the ingrowing cell wall. Later it must be distributed by other means because two equal parts are connected by a number of fine and straight DNA threads. InOscillatoria limosa usually all parts of the centroplasm are interspersed with the DNA network. In surface view, the DNA occasionally seems to consist of a number of independant rods, but in reality these are connected to the general network. Division apparantly occurs by ingrowth of the crosswall and usually results in equal daughter nuclear equivalents although occasionally they are unequal. Four strains ofMicrocoleus vaginatus were found to have nuclear equivalents of the same general appearance as inOscillatoria limosa.

     

Elektronenmikroskopische Untersuchungen des ventralen Diaphragmas von Locusta migratoria und der langsamen Kontraktionswelle nach Fixation durch Gefriersubstitution

Zusammenfassung Die Muskulatur des ventralen Diaphragmas von Locusta besteht aus parallel verlaufenden Muskelfasern, die über glanzscheibenartige Strukturen in den Querverbindungen miteinander verbunden sind. Jede Muskelfaser ist von einer dicken Bindegewebshülle umgeben. Die Fasern sind über Hypodermiszellen mittels Tonofibrillen in der Cuticula verankert.Unkontrahierte Sarkomere haben eine Länge von 5 m und mehr. Eine H-Zone ist angedeutet, eine M-Linie nicht vorhanden. Aktin- und Myosinfilamente (Durchmesser 72 bzw. 160 AE) liegen nicht im Register. Daneben existiert ein dritter, sehr dünner Filamenttyp. Die Z-Zone hat einen gewellten Verlauf und faßt die Aktinfilamente in Bündeln zusammen. Mitochondrien liegen beiderseits der Z-Zone. Das T-System faltet sich in Form von Sarkolemmkerben in das Faserinnere ein und setzt sich in Tubuli nach innen fort. Z-Zonen und Sarkolemmkerben sind miteinander verbunden. T-System und sarkoplasmatisches Retikulum treten durch unregelmäßig verteilte Diaden miteinander in Kontakt.Begrenzter Ca⁺⁺-Entzug läßt Kontraktionswellen von der Länge mehrerer Sarkomere entstehen.Die Fixation durch Gefriersubstitution erzeugt gegenüber Standardverfahren Veränderungen wie Schrumpfung des Sarkoplasmas, Verdickung der Myosinfilamente, Vakuolisierung von Mitochondrien und vesikulärem System. In der Kontraktionswelle verkürzt sich die A-Zone mit zunehmender Sarkomerenkontraktion. Der Durchmesser der Myosinfilamente beträgt 172 AE, die Periodik der Cross-bridges von 305 AE bleibt im mittleren Bereich der Filamente konstant.

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Electron microscope studies of the ventral diaphragm of Locusta migratoria and of the slow wave of contraction after fixation by freeze substitution

Summary The muscular system of the ventral diaphragm of Locusta consists of parallel muscle fibers, which are connected by structures like intercalated discs within transverse bridges. Each muscle fiber is enveloped by a thick sheath of connective tissue. The fibers are attached to the cuticule by means of hypodermic cells with tonofibrils.Uncontracted sarcomeres have a length of 5 m and more. The H-band is slightly indicated, a M-line is not visible. Actin and myosin filaments (diameter 72 respectively 160 AE) are out of register. Moreover there is a third and very thin type of filaments. The Z-band has an undulating shape and collects the actin filaments into bundles. Mitochondria lie on either side of the Z-band. The T-system invaginates as sarcolemmal clefts and continues its course inwards as tubuli. The sarcolemmal clefts are connected with the Z-band. The T-system and the sarcoplasmic reticulum are joined by diads of irregular distribution.Limitated deprivation of Ca⁺⁺ causes waves of contraction with the length of several sarcomeres.Contrary to standard methods the freeze-substitution causes some modifications such as shrinking of the sarcoplasm, thickening of the myosin filaments, vacuolization of mitochondria and vesicular system. Within the waves of contraction the A-band shortenes with increasing sarcomere contraction. The diameter of the myosin filaments measures 172 AE, the 305 AE-period of the cross-bridges remains constant within the middle of the filaments.

Auszug aus der Dissertationsarbeit Elektronenmikroskopische Untersuchungen der Muskulatur des ventralen Diaphragmas von Locusta migratoria und der langsamen Kontraktionswelle unter Anwendung der Gefriersubstitution (Mathematisch-Naturwissenschaftliche Fakultät der Universität Göttingen). Auf Anregung von Herrn Prof. Dr. Schlote und mit Unterstützung durch die Deutsche Forschungsgemeinschaft und die Göttinger Akademie der Wissenschaften.     

Umsatz von Lymphozyten in Blut und Lymphknoten der Ratte

Summary Mature spermatozoa from the seminal vesicles of adult Agriolimax reticulatus have been studied by means of phase contrast and electron microscopy; sperm were either live, or sectioned or mounted whole and shadowed with gold. The cell is of the typical pulmonate sperm type with a simple acrosome and a spiral nucleus comprising the head, and a tail which is ensheathed along its entire length by mitochondrion. The 9 peripheral fibrils of the axial complex show no indication of a double nature. Within the spermatheca or gametolytic gland breakdown of sperm occurs; the nucleus and axial fibre bundle of the flagellum survive the longest. The complexity of the flagellum and the relative simplicity of the acrosome are discussed in light of the ecology of the spermatozoa. Many problems concerning the functional physiology of the sperm organelles remain to be investigated.     

Ultrastructure of mitosis and cytokinesis inZygnema sp. (Zygnematales,Chlorophyta)

Summary Mitosis and cytokinesis have been studied in the green algaZygnema C. A. Agardh using interference-contrast light and transmission electron microscopy. At prophase, the nucleolus disintegrates and numerous extranuclear microtubules near the nuclear periphery penetrate into the nucleoplasm. When aligned in the equatorial plane of the open metaphase spindle the chromosomes are coated with persistent nucleolar fragments. At anaphase, vacuoles intrude into the interzonal spindle region and seemingly contribute to the anaphase movement of the chromosomes. At telophase, the spindle is persistent and the reforming nuclei are separated by cytoplasmic strands containing microtubules, interspersed with vacuoles. Extensive bundles of microtubules, dictyosomes and parallel, slightly inflated ER-profiles extend from the poles of the telophase nucleus along the longitudinal side of the chloroplast. Conceivably, these microtubules guide the nucleus during its post-mitotic migration towards its central interphase position between the two halves of the dividing chloroplast. Throughout the mitotic cycle, ubiquitous dictyosomes, positioned near the chloroplast core, seem very active. Arrays of microtubules run towards these dictyosomes and may conduct the dictyosome-vesicles to the cleavage plane. At metaphase, septum growth becomes visible as an annular ingrowth of the plasmalemma. At late telophase or at entering interphase, an extensive clump of vesicles, associated with longitudinal bundles of microtubules, appears between the leading edges of the advanced furrow. Apparent fusion of these vesicles with the head of the centripetally-growing furrow results in its completion. The pattern of mitosis and cytokinesis inZygnema is compared with that of closely related green algae.     

The role of microtubules during the cytokinetic events of cell wall ontogenesis and papilla development inCarteria crucifera

Summary An ultrastructural study of cytokinesis, cell wall ontogenesis, and papilla development/form inCarteria crucifera Korsh. andChloromonas rosae Ettl was undertaken. After typical phycoplast-mediated cytokinesis, wall ontogenesis begins at the level of Golgi apparatus activation and secretion to the outside of the daughter cells of fibrillar wall precursors which self assemble into the typical chlamydomonad wall (sensuRoberts 1974). As wall ontogenesis approaches the flagellar region of the cell, several precisely timed events occur: flagellar apparatus formation, flagellar emergence, protoplasmic extension in the future papilla area underlined by series of parallel aligned microtubules, wall formation (at least the W₂–W₆ layers), retraction of the protoplasmic extension and loss of underlying microtubules, and final wall modification (gap filling by W₁ material) to yield the characteristic wall papilla. The transient cytoplasmic extensions mimic the shape of the future wall papilla and are maintained, at least inCarteria, by underlying microtubules. Structural and developmental properties of the papilla are characterized and phylogenetic implications are discussed.This research was supported by National Science Foundation Grant DEB 78-0554.     

Licht- und elektronenmikroskopische Untersuchungen von Entwicklungsstadien der FlechteEndocarpon pusillum unter Kulturbedingungen

The lichenEndocarpon pusillum Hedw. was cultivated under laboratory conditions on agar, silica gel and soil substrate. Selected developmental stages of the life cycle (germination, contact between the symbionts, cortex, squamule and perithecia development) were studied by light and scanning electron microscope.—It could be shown that the spores had no rigid spore walls with germination colpies and the spore cells which are in contact with the substrate were formed directly into germination tubes.— Further studies showed that the initial contact between the components was thigmotropic and both the form and the gelatinous matrix around the algal cells play an important role in this process. — The development of the cortex occurs under reduced moisture conditions resulting in a reduced algal reproduction. The thickness of the cortex was dependent on light intensity during cultivation. The cortex originated from hyphae, which developed beyond the algal layer and were combined to a tight network.—Fruiting bodies with spores and hymenial algae were only formed in cultures on soil substrate.

Frau Prof. Dr.Elisabeth Tschermak-Woess zu ihrem 70. Geburtstag gewidmet.     

Associations between membranes and microtubules during mitosis and cytokinesis in caulonema tip cells of the mossFunaria hygrometrica

Summary The interphase nucleus in theFunaria caulonema tip cells is associated with many non-cortical microtubules (Mts). In prophase, the cortical Mts disappear in the nuclear region; in contrast to moss leaflets, a preprophase band of Mts is not formed in the caulonema. The Mts of the early spindle are associated with the fragments of the nuclear envelope. Remnants of the nucleolus remain in the form of granular bodies till interphase. The metaphase chromosomes have distinct kinetochores; the kinetochore Mts are intermingled with non-kinetochore Mts running closely along the chromatin. Each kinetochore is associated with an ER cisterna. ER cisternae also accompany the spindle fibers in metaphase and anaphase. In telophase, Golgi vesicles accumulate in the periphery of the developing cell plate where no Mts are found. The reorientation of the cell plate into an oblique position can be inhibited by colchicine. It is concluded that the ER participates in controlling the Mt system, perhaps via calcium ions (membrane-bound calcium ions have been visualized by staining with chlorotetracycline) but that, on the other hand, the Mt system also influences the distribution of the ER. The occurrence and function of the preprophase band of Mts is discussed.     

Zur osmotischen Beeinflussung der Photosynthese von Cyanophora paradoxa Korsch. durch Saccharose

Zusammenfassung Die Geschwindigkeit der photosynthetischen Sauerstoffentwicklung des sich recht langsam vermehrenden Cyanoms Cyanophora paradoxa ist nur geringfügig niedriger als diejenige anderer Algen (in bezug auf die Chlorophyllkonzentration). Merkwürdigerweise stellt man eine starke Abhängigkeit photosynthetischer Reaktionen (O₂-Entwicklung, CO₂ Fixierung und Hill-Reaktion mit 2,6-Dichlorphenolindophenol) von der im Medium vorgegebenen Konzentration eines Osmotikums fest. Unter bestimmten Voraussetzungen können steigende Saccharosekonzentrationen (bis ca. 0,1 M) die assimilatorische Sauerstoffproduktion zunächst beschleunigen, höhere Saccharose-Konzentrationen (über 0,1 M) hemmen dagegen. Der Hemmeffekt ist unspezifisch und kann auch in Abhängigkeit von Sorbit und Natriumchlorid beobachtet werden. Die bisherigen Versuche sprechen dafür, daß der Hemmeffekt bis zu einer Konzentration von ca. 0,1 M Saccharose während kurzer Einwirkungszeit reversibel ist, bei höheren Konzentrationen jedoch schon irreversible Zellschädigungen anzeigt.

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Sucrose as an effector of photosynthesis in Cyanophora paradoxa korsch

Cyanophora paradoxa, a fresh-water alga, was found to evolve oxygen photosynthetically with activities similar to other plants (50–300 mol O₂/mg chlorophyll·h). In spite of this the doubling time was 10–30 days. The photosynthetic activity turned out to react very sensitively to external osmotic concentrations. In lower concentrations as conventionally used for chloroplast preparations, sucrose—partially irreversibly—inhibited both photosynthetic O₂ evolution and Hill reaction with 2,6-Dichlorophenolindophenol progressively between 0.1 and 0.5 M. Sorbitol and sodium chloride had similar effects. In a medium of low osmolarity (0.025–0.1 M sucrose) the photosynthetic activity was increased. These results were interpreted as consequence of osmotic interactions between the cell and its environment. When the cells are unable to correct the external osmotic pressure, an irreversible degradation of intracellular membranes is initiated, which finally leads to a total decomposition of the eukaryotic cell.

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Abkurzungen EDTA Athylendiamintetraessigsäure - DCPIP 2,6-Dichlorphenolindophenol     

Die Differenzierungsgenese der TSH-Zellen von Xenopus laevis unter Normalbedingungen und nach Thiouracilbehandlung

Zusammenfassung Die Strukturveränderungen der TSH-Zellen von Xenopus laevis im Verlaufe der Normalentwicklung und nach Belastung mit Methylthiouracil sind elektronenmikroskopisch untersucht worden. Folgende Ergebnisse wurden erzielt: Die thyreotropen Zellen lassen sich aufgrund ihrer polymorphen Granulation erstmals bei jungen Larven vereinzelt im Stadium 45, zahlreicher im Stadium 47, nachweisen. Form und Größe der sekretorischen Granula zeigen in verschiedenen Entwicklungs- und Funktionsphasen auffällige Veränderungen. Nach einem Durchmesserminimum im Stadium 49 K (frühe Ausschüttungsphase) erfolget eine Granulavergrößerung und Abrundung der Granulaform bis Stadium 59 K (Speicherphase). Bis Stadium 61 K ist eine Granulaverkleinerung und das Auftreten einer neuen, kleinen, stärker polymorphen Granulapopulation beobachtet worden (Ausschüttung und Neubildung).Nach MTU-Behandlung zeigt sich ein entsprechender Verlauf der Granulaveränderungen, jedoch mit höheren Durchschnittswerten und zeitlich wie stadienbezogenen Verschiebungen gegenüber den Kontrollen. Die funktionelle Deutung der Veränderungen des Granulastatus sowie die übrigen cytologischen Kriterien bestätigen und ergänzen unsere Vorstellungen vom Aktivitätsverlauf des Hypophysen-Schilddrüsen-Systems in der Amphibienontogenese.

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Differentiation of TSH-cells in Xenopus laevis under normal conditions and after thiouracil-treatment

Summary The ultrastructural changes of the TSH-cells in Xenopus laevis have been investigated in the course of normal development and after thiouracil-treatment. Individually at stage 45, and in larger numbers at stage 47, the thyrotropic cells are detected first in young larvae by their polymorph granulation. Significant changes in size and shape of these secretory granules occur during the different developmental and functional periods. The size-minimum at stage 49 K (early discharge period) is followed by an enlargement of the granules and a rounding-off of their shape up to stage 59 K (period of storage). Up to stage 61 K a decrease in granule-size as well as the appearance of a new population of small, more polymorph elements are to be observed (discharge and new formation).After MTU-treatment a corresponding course of granule-modifications is to be found, but if compared with the controls, there are larger granule-sizes as well as variations regarding age and stage of the animals. The granulation and other cytologic criteria confirm and complete current ideas of the functional development of the pituitary-thyroid-system during the ontogeny of the Amphibia.

Mit dankenswerter Unterstützung durch die Deutsche Forschungsgemeinschaft.     

Elektronenmikroskopische Untersuchungen zur Struktur und Funktion der Rektalpapillen von Drosophila melanogaster

Zusammenfassung Die Zellen der vier Rektalpapillen von Drosophila melanogaster sind polar gebaute, hochdifferenzierte, transportaktive Zellen mit großflächigen Ein- und Ausfaltungen des Plasmalemms. Ihre basale und laterale Zellmembran bildet ein Netzwerk von Einfaltungen, aus dem zahlreiche Stapel von Membranpaaren hervorgehen, die mit Mitochondrien vergesellschaftet sind. Apikal besitzt die Zelle ein System von Mikroleisten, an deren Basis ebenfalls Mitochondrien akkumuliert sind (s. Abb. 9). Bei Drosophila werden nach Durchführung der entsprechenden elektronenmikroskopischen Nachweise Natriumionen an den Membranen der apikalen Ausfaltungen, an den Membranen der interzellulären Stapel der Membranpaare, innerhalb deren Lumina und in den basalen und lateralen Einfaltungen gefunden. Eine bevorzugte Lokalisation von Chloridionen ist nicht vorhanden.Diese Feinstrukturaspekte und die Ergebnisse der Nachweisreaktionen für Natrium und Chloridionen werden mit den Verhältnissen bei Calliphora erythrocephala (Gupta und Berridge, 1966) verglichen und die Transportwege der Ionen eingehend diskutiert.

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Electron microscopic studies on the structure and function of the rectal papillae in Drosophila melanogaster

Summary In Drosophila melanogaster the cells of the rectal papillae are highly differentiated and very active in transport. These cells show extensive infoldings of the plasmalemma. The basal and lateral cell membranes form a system of infoldings, continuous with intracellular stacks of paired membranes which are associated with mitochondria. The apex of the cell displays a system of micro-ridges with basal mitochondria (see Fig. 9). In Drosophila Na⁺ ions can be demonstrated by electron microscopy at the membranes of the apical micro-ridges, at the membranes and within the lumina of the intracellular stacks of paired membranes, and within the basal and lateral infoldings. In contrast, there is no predominant localization of Cl^– ions. The fine structure of the cells of the rectal papillae and the results of cytochemical demonstration of Na⁺ and Cl^– ions are compared with the findings of Gupta and Berridge (1966) in Calliphora erythrocephala. The possible pathways for ion transport are discussed in detail.

Mit dankenswerter Unterstützung durch die Deutsche Forschungsgemeinschaft.     

Einbau von Glycin und Serin in Sideramine vom Ferrichrom-Typ bei Pilzen der Gattung Aspergillus in vivo und in vitro

Zusammenfassung Markiertes Glycin und Serin wurde in Ferrichrom, Ferricrocin und Ferrichrysin von vier Stämmen der Gattung Aspergillus zu 1,6–11,8% in vivo eingebaut. Von Aspergillus fumigatus und A. quadricinctus wurden zellfreie Extrakte hergestellt, die Cyclohexapeptide synthetisieren können.

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Incorporation of glycine and serine in sideramines of the ferrichrome type with fungi of the genus Aspergillus in vivo and in vitro

A 1.6–11.8% incorporation of labelled glycine and serine into ferrichrome, ferricrocin and ferrichrysin has been achieved with four strains of Aspergillus in vivo. Cell-free extracts of Aspergillus fumigatus and A. quadricinctus capable of cyclohexapeptide biosynthesis have been prepared.

     

Beeinflussung der Blattzellen vonFontinalis antipyretica durch den Bewuchs vonCocconeis placentula

In a special habitat near Lunz (Mittersee) long time epiphytism ofCocconeis placentula var.tenuistriata and var.klinoraphis onFontinalis antipyretica leaves causes characteristic, strongly localized alterations in the walls of affected cells. They turn brown, may thicken, and may produce cystolithe-like protuberances into the cell lumina. These reactions obviously are brought about by a specific property ofCocconeis, for other epiphytes do not cause any change. The comparison of theCocconeis vegetation on younger and olderFontinalis leaves shows a considerable variability of the reactions mentioned, and in another habitat none could be found. Apparently several factors cause these reactions. Altogether,Cocconeis placentula is not a completely harmless epiphyte under certain circumstances. The alterations of the moss cells may be interpreted partly as a premature aging process, partly as a defensive action corresponding to alterations induced by some parasitic fungi. Furthermore, the reactions ofCocconeis onFontinalis are remarkably parallel to the influence of the dinococcalean algaRaciborskia inermis onSpirogyra grevilleana.

     

Peptidoglycantyp und Zusammensetzung der Zellwandpolysaccharide vonCellulomonas cartalyticum und einigen coryneformen Organismen

Cellulomonas cartalyticum was found to contain a peptidoglycan type different from that of the other species ofCellulomonas. The diamino acid is lysine instead of ornithine and the interpeptide bridge consists ofd-Asp-d-Ser. The same peptidoglycan type occurs inCorynebacterium manihot, Brevibacterium liticum andArthrobacter luteus. These non cellulolytic organisms are most likely not closely related withCellulomonas cartalyticum, as indicated by the very different G+C content of their DNA, although they formed a narrow cluster includingC. cartalyticum when numeric taxonomical methods were applied.

     

Verwertung von Trimethylammoniumverbindungen durch Acinetobacter calcoaceticus

Zusammenfassung Die Verwertung von Carnitin und Carnitinderivaten (O-Acylcarnitine, Carnitincarboxyl-derivate) und strukturverwandten Trimethylammoniumverbindungen (Betaine und Stickstoffbasen) durch Acinetobacter calcoaceticus wurde anhand des Wachstums und des quantitativen Nachweises der Metabolite untersucht. Der Stamm wuchs auf l-Carnitin, l-O-Acylcarnitinen und -Butyrobetain als jeweils einziger C-Quelle. Der Verbrauch dieser Verbindungen und das Wachstum korrelierten mit der Spaltung der C-N-Bindung und mit dem gebildeten Trimethylamin. d-Carnitin wurde metabolisiert, wenn als zusätzliche C-Quelle l-Carnitin im Nährmedium vorhanden war, oder wenn die Bakterien mit l-oder dl-Carnitin vorinkubiert worden waren. Mit d-Carnitin als einziger C-Quelle wuchsen die Bakterien jedoch nicht. Die Bakterien oxidierten Cholin zu Glycinbetain in Gegenwart einer zusätzlichen C-Quelle, Glycinbetain selbst wurde nicht assimiliert. In Hinsicht auf den Abbau quaternärer Stickstoffverbindungen besitzt Acinetobacter calcoaceticus im Vergleich zu anderen Carnitin-verwertenden Bakterienarten einen für ihn charakteristischen Stoffwechselweg.

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Utilization of trimethylammonium-compounds by Acinetobacter calcoaceticus

The utilization of carnitine and carnitine derivatives (O-acylcarnitines, carnitine carboxylderivatives) and structure-related trimethylammonium-compounds (betaines and nitrogen-bases) by Acinetobacter calcoaceticus was studied by means of the control of growth and the quantitative detection of metabolites. The strain grew only on l-carnitine, l-O-acylcarnitines, and -butyrobetaine as the sole carbon sources. The utilization of these compounds and the growth correlated with the cleavage of the C-N bond and thereby with the formation of trimethylamine. d-Carnitine was metabolized, if an additional carbon source, like l-carnitine, was present in the incubation mixture, or if the bacteria were preincubated with l-or dl-carnitine, but no growth was observed on d-carnitine as the sole carbon source. The bacteria oxidized choline to glycinebetaine in the presence of additional carbon sources, glycinebetaine itself was not assimilated. With regard to the catabolism of quaternary nitrogen compounds Acinetobacter calcoaceticus shows a different pathway in comparison with other bacterial species metabolizing carnitine.

     

Aberrant nuclear migration and microtubule arrangement in a defect mutant cell ofMicrasterias thomasiana

Summary Nuclear migration and the spatial arrangement of the participating microtubules are studied inMicrasterias thomasiana and in the defect mutant cellMicrasterias thomasiana f. uniradiata.In both of these cell types the two microtubule systems, the posttelophase system of MT (PTS) and the isthmus system of MT (IS)—which are known to be involved in nuclear migration and anchoring from earlier studies onMicrasterias denticulata—are present in the vicinity of the nucleus. In the mutant cell, however, the orientation of these two MT systems as well as their MT arrangement differ from those in the normalMicrasterias cells. Nuclear migration in the mutant is characterized by a turn of the nucleus and the associated PTS around one of the isthmus invaginations of the cell while in the normalMicrasterias cells it occurs as a straight-lined motion along the longitudinal axis of the cell.The results indicate that the reduction of cell pattern inMicrasterias caused by mutation is attended by a disoriented establishment of the cytoskeleton involved in nuclear migration. From comparison of the nuclear behavior and the MT arrangement in the mutant with that of the normalMicrasterias cells further information on the mechanism of nuclear migration inMicrasterias is obtained. It is suggested that interactions between the microtubule center (MC), the nuclear envelope and areas of the plasma membrane are functional in the formation, orientation and localization of the nucleus associated microtubule-microfilament complex.     

Entwicklungsgeschichte und Ultrastruktur von Pollenkitt und Exine bei nahe verwandten entomophilen und anemophilen Angiospermensippen derAlismataceae,Liliaceae, Juncaceae,Cyperaceae, Poaceae undAraceae

Some closely related members of the monocotyledonous familiesAlismataceae, Liliaceae, Juncaceae, Cyperaceae, Poaceae andAraceae with variable modes of pollination (insect- and wind-pollination) were studied in relation to the ultrastructure of pollenkitt and exine (amount, consistency and distribution of pollenkitt on the surface of pollen grains). The character syndromes of pollen cementing in entomophilous, anemophilous and intermediate (ambophilous or amphiphilous) monocotyledons are the same in principal as in dicotyledons. Comparing present with former results one can summarize: 1) The pollenkitt is always produced in the same manner by the anther tapetum in all angiosperm sub-classes. 2) The variable stickiness of entomophilous and anemophilous pollen always depends on the particular distribution and consistency of the pollenkitt, but not its amount on the pollen surface. 3) The mostly dry and powdery pollen of anemophilous plants always contains a variable amount of inactive pollenkitt in its exine cavities. 4) A step-by step change of the pollen cementing syndrome can be observed from entomophily towards anemophily. 5) From the omnipresence of pollenkitt in all wind-pollinated angiosperms studied one can conclude that the ancestors of anemophilous angiosperms probably have been zoophilous (i.e. entomophilous) throughout.