Characterization of the lipopolysaccharides from eight strains of the cyanobacterium Synechococcus

Lipopolysaccharides have been isolated from eight strains of the unicellular cyanobacterium Synechococcus. Fucose, mannose, galactose, glucose and glucosamine were found in all of the lipopolysaccharides investigated. Additionally, strain-specific sugars are present and permit the chemotyping of lipopolysaccharide. Chemotype I, comprising three strains with a high G+C content of DNA (71-66 mol%), is characterized by a high rhamnose portion and by 3,6-dideoxy-d-arabino-hexose (tyvelose). Chemotype III, represented by three strains with a low G+C content of DNA (55-48 mol%), contains a mannose-polymer with small amounts of 3-O-methyl-mannose, 4-O-methyl-mannose, 2-keto-3-deoxyoctonate and mannosamine. Lipopolysaccharides of the two strains of chemotype II contain 2,3,4-tri-O-methyl-arabinose.Lipid A is difficult to split off from the polysaccharide moiety, but is present in all lipopolysaccharides from the Synechococcus strains. The presence of Lipid A is supported by the finding of -hydroxy fatty acids, predominantly -hydroxypalmitic acid. The distribution of branched -hydroxy fatty acids, detected in small amounts, parallels chemotyping of lipopolysaccharide based on the sugar composition. The phosphorus content of the lipopolysaccharides is low.The pyrogenicity of lipopolysaccharides from two strains is low. Synechococcus lipopolysaccharides have little reactivity in antisera raised in rabbits against homologous cells. As far as tested they do not migrate in immunoelectrophoresis. This confirms the neutral character or low negative charge of Synechococcus lipopolysaccharides.Dedicated to Professor Otto Kandler on occasion of his 60th birthday     

Redox-controlled,in vivo and in vitro phosphorylation of the α subunit of the light-harvesting complex I in Rhodobacter capsulatus

Labelling of Rhodobacter capsulatus cells with (³²P)Pi in a phototrophic culture results in phosphorylation of a membrane-bound polypeptide identified as the subunit of the LHI antenna complex of the photosynthetic apparatus. Phosphorylation of the same polypeptide was also observed by incubation of chromatophores with (³²P)ATP or under conditions of photophosphorylation with ADP and (³²P)Pi. The identity of the phosphorylated LHI- subunit was demonstrated by N-terminal protein sequencing of the phosphorylated polypeptide and by failure of labelling in LHI-defective mutants. Pre-aeration of the samples or addition of the oxidant potassium ferrcyanide stimulated the kinase activity whereas the presence of soluble cytoplasmic proteins impaired phosphorylation in an in vitro assay. No effect resulted from addition of reductants to the assay medium. The results indicate the presence of a membrane-bound protein kinase in R. capsulatus that phosphorylates the subunit of the LHI antenna complex under redox control.Abbreviations Pi inorganic phosphate - SDS-PAGE sodium dodecyl-sulfate polyacrylamide gel electrophoresis     

Die granulären Einschlüsse der Mycobakterien

Zusammenfassung In wachsenden Kulturen (Agar und flüssiges Medium, 37° C) von Mycobacterium phlei, Myc. lacticola und Myc. smegmatis sind die meisten Phosphatgranula nach etwa 48 Std Bebrütung, also in der 2. Hälfte der Wachstumsphase, lichtmikroskopisch zu beobachten.Die Stärke der Granulierung ist vom Verhältnis Stickstoff, Kohlenstoff und Phosphor im Medium und der Gegenwart von Kalium- und Magnesium-Ionen abhängig. In ruhenden und wachsenden Kulturen von Myc. phlei gehen häufig, keineswegs aber regelmäßig Granulierung und Zunahme des Gesamt-P parallel.Elektronenmikroskopische Untersuchungen an zellfreien Extrakten von Myc. phlei und Myc. lacticola deuten auf eine unterschiedliche Zusammensetzung der verschiedenen Granula hin.Im Trichloressigsäureextrakt und Kochsaft von Myc. phlei und Myc. lacticola ließen sich Polyphosphate papierchromatographisch nachweisen.Der Sauerstoffverbrauch durch zellfreie Extrakte von Myc. phlei in Gegenwart bestimmter Substrate ist in der bei 180000· g sedimentierbaren Fraktion wesentlich stärker als im Überstehenden.Die Phosphatgranula sind nicht mit diesen fermenthaltigen, sedimentierbaren Partikeln identisch.Die Bildung und das Verhältnis der verschiedenen Granulatypen zueinander wird diskutiert.     

Perioperative Chemotherapy in Gastroesophageal Cancer. A Retrospective Monocenter Evaluation of 42 Cases

Background

Perioperative chemotherapy increases the overall and progression-free survival of patients suffering from resectable adenocarcinomas of the lower esophagus, gastroesophageal junction and stomach (GEC). Comparing different chemotherapy regimens platin-based protocols with 5-fluorouracil (5-FU)/calcium folinate (CF) or oral fluoropyrimidines were favorable in terms of efficacy and side-effects. However, there is no consensus which regimen is the most efficacious.

Methods

42 consecutive patients with resectable GEC (UICC II and III) were treated with 3 pre- and postoperative chemotherapy cycles each consisting of epirubicin, oxaliplatin and capecitabine (EOX). We analyzed the overall survival, progression-free survival and toxicity retrospectively in comparison to published data.

Results

The median overall survival in our cohort was 29 months and the progression-free survival was 17 months. The most frequent grade 3 and 4 toxicities during preoperative chemotherapy were diarrhea (16.7%), leukocytopenia (9.5%) and nausea (9.5%); overall 38.1% of our patients suffered from grade 3 or 4 toxicity. Surgery was carried out in 83% of our patients, 69% of those achieved R0 resection.

Conclusion

Comparing our data with the results of previously published randomized trials EOX is at least non-inferior with regard to overall survival, progression-free survival and toxicity. In conclusion, EOX is an appropriate perioperative therapy for patients with resectable GEC.     

Beiträge zur Cytologie der Blaualgen

Zusammenfassung Mit Hilfe von Ultradünnschnitten wurde die Substruktur von Phormidium frigidum Fritsch, Phormidium retzii Gom., Oscillatoria limosa Ag., Anabaena variabilis Kütz und Cylindrospermum licheniforme Kütz untersucht.Das Chromatoplasma besteht aus submikroskopischen Lamellen, die bei den einzelnen Arten charakteristische Lamellensysteme bilden. Größere Unterschiede in der Ausbildung und Anordnung der Lamellen bestehen zwischen den Vertretern der Oscillatoriaceen und der Nostocaceen.Das Centroplasma läßt auch im submikroskopischen Bereich keine Abgrenzung gegen das Chromatoplasma erkennen. Es ist dadurch gekennzeichnet, daß das Plasma hier kompakter gelagert ist und die für das Chromatoplasma typischen Lamellen fehlen. Das Grundplasma ist körnig und läßt gewisse kettenförmige Strukturen erkennen.     

fist: an Arabidopsis mutant with altered cell division planes and radial pattern disruption during embryogenesis

A T-DNA-tagged, embryo-defective Arabidopsis thaliana mutant, fist, was identified and shown to exhibit defects in nuclear positioning and cell division orientation beginning at the four-cell stage of the embryo proper. Cell division orientation was randomised, with each embryo exhibiting a different pattern. Periclinal divisions did not occur after the eight-cell embryo proper stage and fist embryos lacked a histologically distinct protoderm layer. Terminal embryos resembled globular-stage embryos, but were a disorganised mass containing 30–100 cells. Some terminal embryos (5%) developed xylem-like elements in outer surface cells, indicating that the fist mutation affects radial pattern. A soybean β-conglycinin seed storage protein gene promoter, active in wild-type embryos from heart stage to maturity, was also active in terminal fist embryos despite their disorganised globular state. This indicated that some pathways of cellular differentiation in fist embryos proceed independently of both organised division plane orientation and normal morphogenesis. Endosperm morphogenesis in seeds containing terminal fist embryos was arrested at one of three distinct developmental stages and appeared unlinked to fist embryo morphogenesis. The β-conglycinin seed storage protein gene promoter, normally active in cellularised wild-type endosperm, was inactive in fist endosperm, indicating abnormal development of fist endosperm at the biochemical level. These data indicate that the fist mutation, either directly or indirectly, results in defects in cell division orientation during the early stages of Arabidopsis embryo development. Other aspects of the fist phenotype, such as defects in endosperm development and radial pattern formation, may be related to abnormal cell division orientation or may occur as pleiotropic effects of the fist mutation. Received: 15 July 1997 / Accepted: 9 September 1997