Plasmatische Strukturen in Experimentell Hervorgerufenen Zellwandverdickungen von Micrasterias Denticulata Bréb

Zusammenfassung Mit Hilfe einer modifizierten Färbemethode nach Crafts (1931) konnte festgestellt werden, daß die bei Teilungsstadien von Micrasterias denticulata nach Turgorverminderung auftretenden Zellwandverliekungen von plasmatischen Fäden durchzogen sind. Das periphere Plasma löst sich daher trotz der Sekretion von Wandmaterial nicht vollständig von der Primärwand.Es wird die mögliche Funktion von plasmatischen Fäden unterschiedlicher Dehnbarkeit für die Form der Wandverdickung diskutiert.

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Protoplasmic structures in artificially produced cell-wall thickenings

Summary With the aid of a modified technique by Crafts (1931) it could be shown that cell-wall thickenings in Micrasterias denticulata, artificially produced by turgor-reduction during cell-growth, are penetrated by protoplasmic filaments. The outer protoplasmic layer is therefore not removed completely from the primary wall during the secretion of cell-wall material. The possible function of protoplasmic filaments differing in their extensibility is discussed in relation to the characteristic form and pattern of the wall-thickenings.

     

Zur photolyse von Indol-3-acetonitril

Summary Alcohol-water solutions of 3-indoleacetonitrile were exposed to ultraviolet light for different time intervals. The products of the auxin destruction were separated on paper chromatograms and tested biologically. Indoleacetonitrile was found to be partially destroyed with ultraviolet radiation. The rate of the auxin destruction increased with the time of illumination. However after 27 hours of illumination the auxin was not completely destroyed. Among the products of the auxin destruction, indole-3-carboxylic acid was identified.

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Mit 1 Textabbildung     

Über die formative Wirksamkeit der 2,3,5-Trijodbenzoesäure (TIBA) im vegetativen und generativen Bereich vonSolanum nigrum

Ohne Zusammenfassung     

Identification of the amino terminal subunit of the glycoprotein of Borna disease virus

The only surface membrane glycoprotein of Borna disease virus (BDV) is synthesized as a polypeptide with a molecular mass of 57 kDa and N-glycosylated to a precursor glycoprotein (GP) of about 94 kDa. It is processed by the cellular protease furin into the C-terminal membrane-anchored subunit GP-C, also known as gp43, and a presumptive N-terminal subunit GP-N, that is highly glycosylated and has a molecular mass of about 51 kDa. However, up to now the latter remained undetected in BDV-infected material. We describe a novel approach to identify glycan masked linear antigenic epitopes. In the present study, GP-N was identified in BDV-infected cells by a combination of lectin precipitation, enzymatic deglycosylation on blot and immunochemistry using an N-terminal specific antiserum. The GP-N has an apparent molecular mass of 45-50 kDa in its glycosylated form and 27 kDa in its deglycosylated form. N-glycan analysis revealed that the precursor GP contains only mannose-rich N-glycans, whereas GP-N and GP-C contain mannose-rich and complex-type N-glycans.     

Optimization of spatiotemporal gene inactivation in mouse heart by oral application of tamoxifen citrate

Inducible and tissue-specific gene inactivation in mice has become a powerful tool to bypass embryonic and postnatal lethality of knockout mice. The most frequently used inducible system is based on Cre recombinase fused to either one or two mutated estrogen receptor ligand binding domains, thus rendering Cre function tamoxifen-dependent. To achieve Cre-mediated inactivation of a given gene, 4-OH tamoxifen (4-OHT) dissolved either in alcohol and/or oil is usually administered by repeated intraperitoneal (i.p.) injections. Since this procedure imposes considerable stress on mice, we compared the effect of tamoxifen citrate, mixed into a standard mouse diet at different concentrations, with that of i.p. administration of 4-OHT on Cre-mediated, heart-specific inactivation of thioredoxin reductase 2. Here we show that tamoxifen citrate in the chow was equally effective as 4-OHT given i.p. Oral tamoxifen administration is thus a convenient and cost-saving way for gene induction, and, most importantly, it reduces stress and avoids adverse effects in mice.     

Die Formbildung vonMicrasterias rotata Ralfs und ihre experimentelle Beeinflussung

Ohne ZusammenfassungUnserem gemeinsamen Lehrer, Prof. Dr. K. Höfler, möchten wir an dieser Stelle unseren ergebenen Dank aussprechen.     

Deregulation of the Egfr/Ras signaling pathway induces age-related brain degeneration in the Drosophila mutant vap

Ras signaling has been shown to play an important role in promoting cell survival in many different tissues. Here we show that upregulation of Ras activity in adult Drosophila neurons induces neuronal cell death, as evident from the phenotype of vacuolar peduncle (vap) mutants defective in the Drosophila RasGAP gene, which encodes a Ras GTPase-activating protein. These mutants show age-related brain degeneration that is dependent on activation of the EGF receptor signaling pathway in adult neurons, leading to autophagic cell death (cell death type 2). These results provide the first evidence for a requirement of Egf receptor activity in differentiated adult Drosophila neurons and show that a delicate balance of Ras activity is essential for the survival of adult neurons.