Topochemische Untersuchungen am neurosekretorischen Zwischenhirn-Hypophysensystem der Albino-Ratte unter normalen und experimentellen Bedingungen

Zusammenfassung Die neurosekretorischen Ganglienzellen der Nuclei supraopticus und paraventricularis der Albinoratte wurden mit topochemischer Routinetechnik unter den Bedingungen länger dauernder Kochsalzbelastung in Form von Trinkwasserdarreichung untersucht. Auch diese Neurone antworten auf eine erhöhte Belastung mit schon bei Ganglienzellen anderer Topik beobachteten unspezifischen Reaktionen, die beschrieben werden. Darüber hinaus tritt bei den Versuchstieren eine paranukleäre positive Perjodsäure-Schiff-Reaktion in Erscheinung. Vorläufig muß offenbleiben, ob in diesem Phänomen ein erster Hinweis auf eine spezifische Zelltätigkeit der untersuchten Ganglienzellen erblickt werden darf.Angaben über Fermentvorkommen und ihre Veränderungen in den Ganglienzellen der Nuclei supraopticus und paraventricularis werden vorbehaltlich der methodisch bedingten Fehler gemacht. Bernsteinsäuredehydrogenase wurde bislang nur in geringem Umfange in den untersuchten Neuronen gefunden.Mit dankenswerter Unterstützung durch die Deutsche Forschungsgemeinschaft.     

Über funktionelle Kernschwellung in den Nuclei supraoptici und paraventriculares des Hundes bei experimentellen Durstzuständen

Zusammenfassung Bei experimentellen Durstzuständen vergrößern sich die Kerne der Ganglienzellen des Nucleus supraopticus und paraventricularis des Hundes in 8 Tagen um 16% bzw. 19%, in 14 Tagen um 37% bzw. 49% gegenüber den Durchschnittswerten bei Normaltieren.Nach 14tägiger Durstperiode und anschließender 8tägiger unbeschränkter Wasseraufnahme verkleinern sich die Ganglienzellkernvolumina der genannten Zwischenhirngebiete wieder um 7% (N. s.o.) bzw. um 17% (N. p.v.). Die Kernschwellung ist also reversibel.Vergleichsmessungen an den Ependymkernen des III. Ventrikels zeigen keine echten Unterschiede zwischen den Durchschnittswerten der einzelnen Versuchsreihen.Unter Heranziehung der auf experimentellem Wege gewonnenen Kenntnisse über das Zwischenhirn-Hypophysensystem lassen sich die unter experimentellen Bedingungen zu erzielenden reversiblen Kernschwellungen in den Nuclei supraoptici et paraventriculares als weiterer Hinweis auf eine zentrale Produktion der sog. Hinterlappenhormone deuten.Die Untersuchung wurde mit Unterstützung der Deutschen Forschungsgemeinschaft durchgeführt.     

Characterization of the iron-binding properties of pyoverdine using electron-capture dissociation-tandem mass spectrometry

Pyoverdines (PVD) are a group of siderophores produced by fluorescent Pseudomonads. Identification of PVD variants mostly relies on liquid chromatography-tandem mass spectrometry (LC–MS/MS) using collision-induced dissociation (CID). Here, both CID and the novel dissociation technique electron-capture dissociation (ECD) were applied to characterize PVD succinamide and its Fe(III)-chelated complex. The results clearly showed that ECD produced diagnostic side chain fragmentation of the PVD peptide chain and preserved the labile Fe(III) binding to the chromophore in contrast to CID. The ECD technique is therefore expected to support the understanding of strain-specific Fe(III) transport processes of PVDs.     

Structure and antithrombin-binding properties of heparin isolated from the clams Anomalocardia brasiliana and Tivela mactroides

Heparin with high anticoagulant activity was isolated from the two marine clam species Anomalocardia brasiliana and Tivela mactroides. A large portion of the polysaccharide chains of both preparations bound with high affinity to immobilized antithrombin. Titrations monitored by tryptophan fluorescence showed that clam polysaccharide chains with Mr approximately 22,500 contained up to three binding sites for antithrombin and that the binding constants for the interaction of these chains with antithrombin were higher than those reported for mammalian heparin of comparable size. Structural analysis of clam heparin fractions and subfractions of clam heparin with differing affinity for immobilized antithrombin revealed the presence of large amounts (up to 25-30% of the total disaccharide units) of the 3-O-sulfated saccharide sequences (-GlcNSO3)-GlcA-GlcNSO3(3-OSO3)- and (-GlcNSO3)-GlcA-GlcNSO3(3,6-di-OSO3)-, previously identified as unique markers for the antithrombin-binding region of heparin. The content of these saccharide sequences was found to increase with increasing affinity of the parent polysaccharide for antithrombin. Structural analysis of the clam heparins also demonstrated the occurrence of a novel saccharide sequence, tentatively identified as (-GlcNSO3)-IdA-GlcNSO3(3,6-di-OSO3)-, that has not previously been found in heparin or related polysaccharides. The contents of this latter sequence, at most 3-4% of the total disaccharide units, showed no correlation with the affinity for antithrombin.     

Effects of immobilizing agents and procedures on viability of cultured celery (Apium graveolens) cells

Summary In an attempt to develop concurrent permeabilization/immobilization systems for the production of secondary plant metabolites, the effects of chitosan, alginate, carrageenan gel and carrageenan/chitosan copolymers as immobilizing agents and immobilization procedures on viability of culturedApium graveolens cells have been examined. Chitosan immobilization, ascorbic and succinic acid resulted in low viability of plant cells but use of carrageenan/chitosan copolymers enabled maintenance of viable cell lines providing the potential for concurrent immobilization/permeabilization of cells and elicitation of secondary metabolites by chitosan.     

Production and conversion of chitosan with cultures of Mucor rouxii or Phycomyces blakesleeanus

Summary Highly deacetylated chitosan was accumulated in the mycelia ofMucor rouxii orPhycomyces blakesleeanus. These cultures also effected the deacetylation of the chitin ofAspergillus niger mycelium into chitosan. After 96 hours of incubation with these cultures the degree of acetylation of commercial crab shell chitosan was reduced from 25.0% to values between 4.3 and 8.6%. The potential exists for the production of chitosans with tailored physico-chemical properties from waste chitin.     

Group II intron self-splicing. Alternative reaction conditions yield novel products

Reaction parameters were modified to enhance the in vitro reaction rate and to reveal partial and novel reactions of the group II intron 5g of the mitochondrial gene from Saccharomyces cerevisiae encoding cytochrome c oxidase subunit I. One alteration yields separate 5'- and 3'-exons plus linear excised intron as the main products. A linear reaction intermediate, containing intron and 3'-exon, and products resulting from cleavages at two unexpected sites were identified. Spliced exon "reopening," a novel reaction between excised intron and spliced exons, appears responsible for separate 5'- and 3'-exon products.