Über die postlarvale Entwicklung von Flöhen (Insecta,Siphonaptera), unter besonderer Berücksichtigung der sogenannten “Flügelanlagen”

Lateral appendages on the mesothorax of flea pupae, regarded to be wing buds by Sharif, have been found in species of the Ceratophylloidea investigated by other authors and me, but not in the Pulicidae. The appendages become basal parts of the mesepimeron which speaks against their wing character. Ecological data are given.

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Über die postlarvale Entwicklung von Flöhen (Insecta, Siphonaptera), unter besonderer Berücksichtigung der sogenannten Flügelanlagen

Die Abkürzungen in der Beserchriftung der Abbildungen Anh Anhang - Bo Borste - Cut Kutikula - D Darm - F Falte - And E blindgeschlossenes Endedes Anhanges - Ga Ganglion - H kutikulare Hülle der Ausstülpung - Hy Hypodermis - Im Imago, imaginal - L Larvae, larval - Lob Lobus - M Muskel - Mes Mesepimeron - N Bauchmark - OGa Oberschundganglion - P Puppe, pupal - p Beinanlage - Per Peripodialhöhle, hier immer ihr oberer Rand - Sti Stigma - Tr Tracheen     

Influence of phloem transport, N-fertilization and ion accumulation on sucrose storage in the taproots of fodder beet and sugar beet

To investigate the factors governing the accumulation of sucroseand amino acids in the taproots of sugar beet, their contentswere measured in the leaves, phloem sap and the taproots ofsugar beet, fodder beet and a hybrid between both, grown oneither 3.0 or 0.5 mM nitrate. In the taproots the contents ofmalate, citrate and inorganic ions were also determined. Forthe high sucrose accumulation in sugar beet as compared to theother varieties three factors were found. (a) In sugar beet,less amino acids and more sucrose are taken up into the phloemthan in fodder beet. (b) In sugar beet, the sucrose and aminoacid syntheses are less sensitive to the nitrate concentrationsthat are required for optimal plant growth than in other varieties.In fodder beet, upon raising the nitrate concentration from0.5 mM to 3 mM, the synthesis and storage of sucrose is decreasedand that of amino acids increased. The corresponding valuesin sugar beet (0.5 mM) are similar to those in fodder beet andare not much affected by an increase of nitrate. (c) The sucroseaccumulation is limited by the accumulation of inorganic ionsin the taproots. The sucrose content in the taproots is negativelycorrelated to the total ion content. Whereas sucrose representstwo-third of all solutes in the taproots of sugar beet, it amountsto only one-third of the solutes in fodder beet taproots. Key words: Amino acids, Beta vulgans L, phloem sap, potassium, sucrose storage, sugar beet, taproots, transport     

Der freie Raum synchroner Chlorella

Zusammenfassung Der freie Raum innerhalb der Zellwand von Chlorella fusca wurde nach einer Verdünnungsmethode mit ¹⁴C-mannit bestimmt. ³⁶Cl-Perchlorat ist wegen des Donnan-Effekts weniger geeignet. Korrektur für außen anhaftendes Wasser wurde mit ¹⁴C-Dextran durchgeführt. Während der Lichtphase (16 Std) des Wachstumscyclus nimmt der freie Raum von 11 auf 4% des Zellvolumens ab, und er nimmt während der ersten 8 Std der Dunkelphase (12 Std) wieder zu. Während der Lichtphase vermindert sich, nach dem Volumen des freien Raums zu urteilen, die Zellwanddicke; offenbar bleibt die Zellwandsynthese gegenüber dem Zellwachstum zurück.

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The free space of synchronous Chlorella

Summary The free space in the cell wall of Chlorella fusca has been determined by a dilution method with ¹⁴C-mannitol. Owing to a Donnan effect, ³⁶Cl-perchlorate is less suitable, ¹⁴C-dextran was used to correct for external water. During the light phase (16 h) of the generation cycle, the free space decreases from 11 to 4% of the cell volume. It increases again during the first 8 h of the dark phase (12 h). During the light phase, the cell wall, as judged by the free space volume, thins; apparently cell wall synthesis does not fully kepp in step with cell growth.

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Herrn Prof. Dr. O. Kratky zum 70. Geburtstag gewidmet.     

CCL1-CCR8 interactions: an axis mediating the recruitment of T cells and Langerhans-type dendritic cells to sites of atopic skin inflammation

Atopic dermatitis represents a chronically relapsing skin disease with a steadily increasing prevalence of 10-20% in children. Skin-infiltrating T cells, dendritic cells (DC), and mast cells are thought to play a crucial role in its pathogenesis. We report that the expression of the CC chemokine CCL1 (I-309) is significantly and selectively up-regulated in atopic dermatitis in comparison to psoriasis, cutaneous lupus erythematosus, or normal skin. CCL1 serum levels of atopic dermatitis patients are significantly higher than levels in healthy individuals. DC, mast cells, and dermal endothelial cells are abundant sources of CCL1 during atopic skin inflammation and allergen challenge, and Staphylococcus aureus-derived products induce its production. In vitro, binding and cross-linking of IgE on mast cells resulted in a significant up-regulation of this inflammatory chemokine. Its specific receptor, CCR8, is expressed on a small subset of circulating T cells and is abundantly expressed on interstitial DC, Langerhans cells generated in vitro, and their monocytic precursors. Although DC maintain their CCR8+ status during maturation, brief activation of circulating T cells recruits CCR8 from intracytoplamic stores to the cell surface. Moreover, the inflammatory and atopy-associated chemokine CCL1 synergizes with the homeostatic chemokine CXCL12 (SDF-1alpha) resulting in the recruitment of T cell and Langerhans cell-like DC. Taken together, these findings suggest that the axis CCL1-CCR8 links adaptive and innate immune functions that play a role in the initiation and amplification of atopic skin inflammation.     

Protein expression pattern in experimental pneumococcal meningitis

In this study, we investigated cytokine expression during experimental pneumococcal meningitis. Mice were intracisternally infected with Streptococcus pneumoniae and treated with ceftriaxone starting at 24 h after infection. At different time points before and after antibiotic therapy, the cytokine expression pattern was determined in mouse brains using protein arrays. Underlining the power of this method, the meningitis-relevant cytokines interleukin-1beta (IL-1beta), IL-6, KC, macrophage inflammatory protein-2 (MIP-2), and monocyte chemoattractant protein-1 (MCP-1/CCL2) were markedly elevated in infected animals. Newly identified proteins during the acute stage of the disease (until 30 h after infection) included lymphotactin (XCL-1), MIP-1gamma (CCL9) and MCP-5 (CCL12), cytokine responsive gene- 2 (CRG-2/CXCL10) and CXCL16, and insulin-like growth factor binding protein 3 (IGFBP3). During later stages, an induction of T-cell activation-3 (TCA-3/CCL1), platelet factor-4 (PF-4/CXCL4) and stromal derived factor-1alpha (SDF-1alpha/CXCL13), and IL-4 was observed. The validity of this method was supported by an additional ELISA analysis of the expression profile of CXCL16 and IGFBP3, which was identical to that observed by protein array. In conclusion, the use of protein array technology led to an extension of the current picture of protein expression in pneumococcal meningitis. Most important, new factors that might play a role in pneumococcal meningitis were identified.     

Solute accumulation and decreased photosynthesis in leaves of potato plants expressing yeast-derived invertase either in the apoplast, vacuole or cytosol

Potato (Solanum tuberosum cv. Désirée) plants expressing yeast invertase directed either to the apoplast, vacuole or cytosol were biochemically and physiologically characterised. All lines of transgenic plants showed similarities to plants growing under water stress. Transformants were retarded in growth, and accumulated hexoses and amino acids, especially proline, to levels up to 40-fold higher than those of the wild types. In all transformants rates of CO₂ assimilation and leaf conductance were reduced. From the unchanged intercellular partial pressure of CO₂ and apoplastic cis-abscisic acid (ABA) content of transformed leaves it was concluded that the reduced rate of CO₂ assimilation was not caused by a limitation in the availability of CO₂ for␣the ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco). In the transformants the amount of Rubisco protein was not reduced, but both activation state and carboxylation efficiency of photosynthesis were lowered. In vacuolar and cytosolic transformants this inhibition of Rubisco might be caused by a changed ratio of organic bound and inorganic phosphate, as indicated by a doubling of phosphorylated intermediates. But in apoplastic transformants the pattern of phosphorylated intermediates resembled that of leaves of water-stressed potato plants, although the cause of inhibition of photosynthesis was not identical. Whereas in water-stressed plants increased contents of the phytohormone ABA are supposed to mediate the adaptation to water stress, no contribution of ABA to reduction of photosynthesis could be detected in invertase transformants. Received: 29 May 1996 / Accepted: 30 December 1996     

Das Verhalten von Chlorella fusca gegenüber Perchlorat und Chlorat

Zusammenfassung Das Verhalten von Chlorella fusca gegenüber markiertem Chlorat und Perchlorat wurde untersucht. Unabhängig von den Bedingungen wird Perchlorat nur zu einem geringen Maß aufgenommen, und es wird nicht zu Chlorid reduziert. Dagegen wird Chlorat mit Michaelis-Menten-Kinetik reduziert. Die Geschwindigkeit wird durch Belichtung erhöht und durch DNP, Cyanid und Jodacetat vermindert. Die Reduktion des Chlorats wird durch Nitrat und Nitrit kompetitiv gehemmt. Offenbar erfolgen Aufnahme und Reduktion von Chlorat durch Mechanismen, die dem Stoffwechsel von Nitrat und Nitrit dienen. Nach Züchtung auf Ammonium als einziger Stickstoffquelle reduziert Chlorella anfangs Chlorat nicht. Die Dunkelreduktion durch nitratgezüchtete Chlorella wird durch eine stickstofffreie Vorperiode beschleunigt.

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The action of Chlorella fusca on perchlorate and chlorate

Summary The reactions of labelled chlorate and perchlorate with Chlorella fusca have been studied. Independently of conditions, perchlorate is absorbed only to a small extent, and it is not reduced to chloride. In contrast, chlorate is reduced with Michaelis-Menten kinetics. The velocity of reduction is higher in the light than in the dark, and is depressed by DNP, cyanide and iodoacetate. The reduction of chlorate is competitively inhibited by nitrate and nitrite. Apparently uptake and reduction of chlorate are mediated by mechanisms evolved for nitrate and nitrite metabolism. Chlorella grown on ammonium as the only nitrogen source at first does not reduce chlorate. The velocity of reduction in the dark by nitrate-grown Chlorella is enhanced by a period without nitrogen before the test.

     

Real-time monitoring of the membrane-binding and insertion properties of the cholesterol-dependent cytolysin anthrolysin O from Bacillus anthracis

Bacillus anthracis has recently been shown to secrete a potently hemolytic/cytolytic protein that has been designated anthrolysin O (ALO). In this work, we initiated a study of this potential anthrax virulence factor in an effort to understand the membrane-binding properties of this protein. Recombinant anthrolysin O (rALO35-512) and two N-terminally truncated versions of ALO (rALO390-512 and rALO403-512) from B. anthracis were overproduced in Escherichia coli and purified to homogeneity. The role of cholesterol in the cytolytic activity of ALO was probed in cellular cholesterol depletion assays using mouse and human macrophage-like lines, and also Drosophila Schneider 2 cells. Challenging the macrophage cells with rALO35-512, but not rALO390-512 or rALO403-512, resulted in cell death by lysis, with this cytolysis being abolished by depletion of the membrane cholesterol. Drosophila cells, which contain ergosterol as their major membrane sterol, were resistant to rALO-mediated cytolysis. In order to determine the molecular mechanism of this resistance, the interaction of rALO with model membranes comprised of POPC alone, or with a variety of structurally similar sterols including ergosterol, was probed using Biacore. Both rALO35-512 and rALO403-512 demonstrated robust binding to model membranes composed of POPC and cholesterol, with amount of protein bound proportional to the cholesterol content. Ergosterol supported greatly reduced binding of both rALO35-512 and rALO403-512, whereas other sterols tested did not support binding. The rALO403-512--membrane interaction demonstrated an equilibrium dissociation constant (KD) in the low nanomolar range, whereas rALO35-512 exhibited complex kinetics likely due to the multiple events involved in pore formation. These results establish the pivotal role of cholesterol in the action of rALO. The biosensor method developed to measure ALO recognition of cholesterol in a membrane environment could be extended to provide a platform for the screening of inhibitors of other membrane-binding proteins and peptides.     

The NLRP3 inflammasome contributes to brain injury in pneumococcal meningitis and is activated through ATP-dependent lysosomal cathepsin B release

Streptococcus pneumoniae meningitis causes brain damage through inflammation-related pathways whose identity and mechanisms of action are yet unclear. We previously identified caspase-1, which activates precursor IL-1 type cytokines, as a central mediator of inflammation in pneumococcal meningitis. In this study, we demonstrate that lack of the inflammasome components ASC or NLRP3 that are centrally involved in caspase-1 activation decreases scores of clinical and histological disease severity as well as brain inflammation in murine pneumococcal meningitis. Using specific inhibitors (anakinra and rIL-18-binding protein), we further show that ASC- and NLRP3-dependent pathologic alterations are solely related to secretion of both IL-1β and IL-18. Moreover, using differentiated human THP-1 cells, we demonstrate that the pneumococcal pore-forming toxin pneumolysin is a key inducer of IL-1β expression and inflammasome activation upon pneumococcal challenge. The latter depends on the release of ATP, lysosomal destabilization (but not disruption), and cathepsin B activation. The in vivo importance of this pathway is supported by our observation that the lack of pneumolysin and cathepsin B inhibition is associated with a better clinical course and less brain inflammation in murine pneumococcal meningitis. Collectively, our study indicates a central role of the NLRP3 inflammasome in the pathology of pneumococcal meningitis. Thus, interference with inflammasome activation might be a promising target for adjunctive therapy of this disease.