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.

     

Physiological and biochemical contributions to the taxonomy of the genus prototheca

Five physiological and biochemical characters, which had proved to be valuable for the taxonomy of the genus Chlorella, were studied in the genus Prototheca. There is no hydrogenase activity and no liquefaction of gelatin. Most strains are very acidtolerant (limit of growth at pH 2.0 or 2.5) and very salt-tolerant (limit of growth at 4 or 5% NaCl). Two strains grow well at 38°C. The 16 strains, which were previously assigned to seven taxa, fall into four different groups. Our results tend to support the assumption that Prototheca might be related to Chlorella protothecoides.     

Co-localization of ecdysteroid receptors and c-fos-like protein in the brain of Manduca sexta larvae

Summary The presence of c-fos, a marker for cell activation, was investigated in cerebral neurons actively expressing ecdysteroid receptors during larval-pupal development in the tobacco hornworm, Manduca sexta. Colocalization was accomplished by ecdysteroid autoradiography using the tritiated high affinity 20-hydroxyecdysone agonist ponasterone A and immunocytochemistry with an antibody to a peptide sequence which is highly conserved in both human and murine c-fos. Immunoreactivity to a c-fos-like protein(s) was present in nuclei of many neurons of all the developmental stages examined. However, with the exception of the optic lobe, cells expressing nuclear ecdysteroid receptors were more immunoreactive than non-ecdysteroid-binding neurons. These data suggest that ecdysteroid-induced gene activation and translation may involve c-fos expression. Offprint requests to: H.-J. Bidmon     

Stimulation of the anaerobic growth ofSalmonella typhimurium by reduction ofl-carnitine,carnitine derivatives and structure-related trimethylammonium compounds

In view of the development of al-carnitine deficiency, the metabolism ofl-carnitine and structure-related trimethylammonium compounds was studied inSalmonella typhimurium LT₂ by means of thin-layer chromatography (TLC).l-Carnitine, crotonobetaine and acetyl-l-carnitine stimulated the anaerobic growth in a complex medium significantly. The stimulation depended on the formation of -butyrobetaine. The reduction ofl-carnitine proceeded in two steps: (1) Dehydration of thel-carnitine to crotonobetaine, (2) hydrogenation of crotonobetaine to -butyrobetaine. The reduction of crotonobetaine was responsible for the growth stimulation. Terminal electron acceptors of the anaerobic respiration such as nitrate and trimethylamine N-oxide, but not fumarate, suppressed the catabolism ofl-carnitine completely. Glucose fermentation, too, inhibited the reduction ofl-carnitine but optimal growth with a high carnitine catabolism was achieved byd-ribose. The esters of carnitine with medium- and long-chain fatty acids inhibited the growth considerably because of their detergent properties.Abbreviations TLC thin-layer chromatography     

Physiological and biochemical contributions to the taxonomy of the genera Ankistrodesmus and Scenedesmus

The 17 Ankistrodesmus strains studied do not produce extracellular amylolytic enzymes. 20 out of 28 Scenedesmus strains, however, are able to hydrolyse starch.The groups of strains previously characterized physiologically and biochemically were assigned to established species of the genera Ankistrodesmus (including Monoraphidium) and Scenedesmus.Abbreviation GC Guanine + cytosine     

Intracellular appearance of nitrite and nitrate in nitrogen-starved cells of Ankistrodesmus braunii

Summary The occurrence of heterotrophic nitrification in nitrogen-starved cells of Ankistrodesmus braunii was confirmed. The levels of nitrate and nitrite were measured over a period of four weeks. The validity of quantitative determinations in the presence of highly active nitrate and nitrite reductases is discussed. Whereas free hydroxylamine as an intermediate could not be detected, increased hydroxylamine oxidase activity was found in nitrogen-starved cultures. Nitrite reductase and hydroxylamine oxidase can be assigned to particles by sucrose density gradient centrifugation. The possible involvement of microbodies, which were found to be present in Ankistrodesmus, in metabolic processes during nitrogen starvation is discussed.Abbreviations NR nitrate reductase - NiR nitrite reductase - NNEDA N-(1-naphthyl)ethylenediaminedihydrochloride - DCPIP 2,6-dichlorophenolindophenol - EDTA ethylenediaminetetraacetic acid - TCA trichloroacetic acid - DAB 3,3-diaminobenzidine - AT 3-amino-1H-1,2,4-triazole - AMP 2-amino-2-methyl-1,3-propanediol     

Genetische Untersuchungen zur Inkompatibilität im Culex-pipiens-Komplex

Zusammenfassung Bei Kreuzungen zwischen Culex pipiens-Populationen verschiedener geographischer Herkunft werden drei Kreuzungstypen festgestellt: normale Kreuzbarkeit, reduzierte Kreuzbarkeit und Inkompatibilität (Nichtkreuzbarkeit). Die drei Kreuzungstypen sind mit Hilfe der Embryonierungsrate, der Schlüpfrate und der entstehenden Nachkommenschaft gegeneinander abgrenzbar. Bei Inkompatibilität sind 99.9% der sich entwickelnden Embryonen letal und etwa 0.1% der Tiere schlüpfen und sind fertile, diploide Weibchen. Die Aktivierung des Eies erfolgt durch das Spermium. Es liegt induzierte, meiotische Parthenogenese vor. Die diploiden, parthenogenetischen Weibchen gehen aus einer Oocyte 2. Ordnung oder aus Teilungsprodukten einer Oocyte 2. Ordnung hervor. Bei den letalen, haploiden Embryonen beteiligt sich das Spermium nicht am Aufbau des Embryos.

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Genetic investigations on the incompatibility in the Culex pipiens complex

Summary In crosses between populations of the mosquito Culex pipiens of different geographical origin three crossing types have been found (1) crosses with normal offspring (2) crosses with reduced offspring and (3) crosses that show almost total incompatibility. In the case of incompatible crosses 99.9% of the developing embryos are lethal and only about 0.1% of the embryos hatch and develop into fertile diploid females. The origin of the exceptional diploid females has been investigated by means of the marker genes Kuf, r, w, var, y and ru. These females develop from a diploid oocyte or from a diploid nucleus that originated by fusion of the pronucleus and the last polar body. This has been concluded from the frequency of homozygous and heterozygous offspring from heterozygous females, the frequency of equational separation of different genes and the distribution of cross-over gametes in the exceptional females. Based on the genetical data it is argued that induced meiotic parthenogenesis takes place. The sperm does not play any part in the production of the diploid females and the lethal embryos. After the activation of the egg the sperm moves to the center of the egg but it does not succeed to fuse with the pronucleus. As a result the pronucleus starts to develop into a haploid embryo in about 99.9% and only in a few cases is the diploidy restored by a change in the meiotic process in the egg.

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Teil einer Dissertation der Math.-Nat. Fakultät der Universität Mainz

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Danksagung: Herrn Prof. Dr. H. Laven danke ich für die Bereitstellung des Untersuchungsmaterials sowie für die Anregungen bei der Durchführung der Arbeit.

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Angenommen durch H. Stubbe     

Die Schnecken(Gastropoda Prosobranchia) der deutschen Meeresgebiete und brackigen Küstengewässer

Zusammenfassung 1. Im Anschluß an eine frühere taxonomische Bearbeitung der Muscheln oder Bivalvia (Ziegelmeier 1957) werden Bestimmungsschlüssel für die Schnecken (Gastropoda Prosobranchia) der deutschen Meeresgebiete und brackigen Küstengewässer vorgelegt.2. Die Bestimmungsschlüssel basieren auf Schalenmerkmalen. Sie werden durch 20 Tafeln und 7 Abbildungen illustriert.3. Eine kurze Einführung in die äußere Anatomie der Gastropoda und Erläuterungen technischer Termini sollen auch dem jungen Studenten und interessierten Laien eine Bestimmung ermöglichen.

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The snails (Gastropoda Prosobranchia) of the German marine areas and brackish coastal waters

Following a systematic treatment of the Bivalvia (Ziegelmeier 1957), this paper presents a taxonomic survey of the Gastropoda species found in marine and coastal waters near Germany; it includes species known from other countries bordering the North Sea and Baltic Sea. Employing taxonomic keys and numerous photographic illustrations, determinations are based on shell structures. Definitions of technical terms and explanations of pertinent details of gastropod anatomy are given in order to make determinations possible also for beginning students and interested laymen.