Tobacco mosaic virus protein: kinetic and equilibrium studies on the pH-dependent transition. A-protein yields double disc.

Concentration dependent and temperature dependent stopped-flow experiments on the transition A-protein→double disc show a triphasic reaction consisting of a nucleation phase, a propagation phase and a slow redistribution of polymer size which involves the dissociation of “overshoot” aggregates into double discs and smaller aggregates. No first order rate process is observed under the present experimental conditions. Equilibrium circular dichroism data and preliminary kinetic data at various temperatures indicate a change at about 21°C which might be correlated to a partial transition double disc→helix parallelled by a further shift in the equilibrium of double disc formation; from both data the thermodynamic and activation parameters for the A-protein→double disc transition are estimated.     

Soil Bacterial Community Shifts after Chitin Enrichment: An Integrative Metagenomic Approach

Chitin is the second most produced biopolymer on Earth after cellulose. Chitin degrading enzymes are promising but untapped sources for developing novel industrial biocatalysts. Hidden amongst uncultivated micro-organisms, new bacterial enzymes can be discovered and exploited by metagenomic approaches through extensive cloning and screening. Enrichment is also a well-known strategy, as it allows selection of organisms adapted to feed on a specific compound. In this study, we investigated how the soil bacterial community responded to chitin enrichment in a microcosm experiment. An integrative metagenomic approach coupling phylochips and high throughput shotgun pyrosequencing was established in order to assess the taxonomical and functional changes in the soil bacterial community. Results indicate that chitin enrichment leads to an increase of Actinobacteria, γ-proteobacteria and β-proteobacteria suggesting specific selection of chitin degrading bacteria belonging to these classes. Part of enriched bacterial genera were not yet reported to be involved in chitin degradation, like the members from the Micrococcineae sub-order (Actinobacteria). An increase of the observed bacterial diversity was noticed, with detection of specific genera only in chitin treated conditions. The relative proportion of metagenomic sequences related to chitin degradation was significantly increased, even if it represents only a tiny fraction of the sequence diversity found in a soil metagenome.     

Modulation of endothelial cell proliferation,adhesion, and motility by recombinant heparin-binding domain and synthetic peptides from the type I repeats of thrombospondin

Thrombospondin is an inhibitor of angiogenesis that modulates endothelial cell adhesion, proliferation, and motility. Synthetic peptides from the second type I repeat of human thrombospondin containing the consensus sequence -Trp-Ser-Pro-Trp- and a recombinant heparin binding fragment from the amino-terminus of thrombospondin mimic several of the activities of the intact protein. The peptides and heparin-binding domain promote endothelial cell adhesion, inhibit endothelial cell chemotaxis to basic fibroblast growth factor (bFGF), and inhibit mitogenesis and proliferation of aortic and corneal endothelial cells. The peptides also inhibit heparin-dependent binding of bFGF to corneal endothelial cells. The antiproliferative activities of the peptides correlate with their ability to bind to heparin and to inhibit bFGF binding to heparin. Peptides containing amino acid substitutions that eliminate heparin-binding do not alter chemotaxis or proliferation of endothelial cells. Inhibition of proliferation by the peptide is time-dependet and reversible. Thus, the antiproliferative activities of the thrombospondin peptides and recombinant heparin-binding domain result at least in part from competition with heparin-dependent growth factors for binding to endothelial cell proteoglycans. These results suggest that both the Trp-Ser-Xaa-Trp sequences in the type I repeats and the amino-terminal domain play roles in the antiproliferative activity of thrombospondin.     

Trifluoperazine binding to calmodulin: a shift reagent 43CA NMR study

43Ca NMR experiments of Ca2+ binding to calmodulin (CaM) were performed in the presence and absence of the calmodulin antagonist trifluoperazine (TFP). By making use of the shift reagent Dy(PPP)(7-) (a 1:2 complex of DyCl3 and Na5P3O10) we have succeeded in separating the 43Ca resonances of protein-bound Ca2+ and free Ca2+ in the otherwise unresolved spectra. This experimental strategy has allowed us to demonstrate unequivocally that the affinity of CaM for Ca2+ is markedly increased in the presence of TFP. Thus Ca2+ is not liberated from the protein upon addition of TFP as had been suggested based on earlier 43Ca NMR experiments (Shimuzu, T., Hatano, M., Nagao, S. and Nozawa, Y. (1982), Biochem. Biophys. Res. Comm. 106, 1112-1118).     

Einige Daten zum Blutbild des Rothirsches (Cervus elaphus L.)

Zusammenfassung Es werden einige Daten zur Kenntnis des Blutbildes vom Rothirsch (Cervus elaphus L.) mitgeteilt. In hämatologischer Beziehung besteht eine weitgehende Übereinstimmung mit den kleinen Wiederkäuern Schaf und Ziege, nach Leukozytenzahl und Saponinempfindlichkeit der Erythrozyten weist das Hirschblut deutliche Unterschiede gegenüber domestizierten Wiederkäuern auf.Unter Mitwirkung der med.-techn. Assistentin, Fräulein Sybille Buchheim.     

Glycolipid toxins from parasitised annual ryegrass: A comparison with tunicamycin

A comparative study between the glycolipid toxins (corynetoxins) isolated from parasitised annual ryegrass and the nucleoside antibiotic complex tunicamycin revealed many similarities in physical, chemical and biological properties. These similarities suggest that the corynetoxins comprise another series of tunicamycin-like antibiotics.     

Selektionsverfahren für die Züchtung von Speisekartoffeln

Zusammenfassung Es wird ein Selektionsverfahren zur Ermittlung verschiedener Speisequalitätsmerkmale an Populationen beschrieben. Die Verfärbung derKartoffeln nach dem Kochen hat eine erhebliche Qualitätsminderung zur Folge, deshalb sind nicht oder nur gering verfärbende Speisekartoffeln besonders wichtig. Für die Züchtung nicht verfärbender Speisekartoffeln gibt die Prüfung dieses Merkmals an Populationen wichtige Hinweise. Dieser Populationstest läßt auch erkennen, welche Kreuzungseltern das gewünschte Merkmal gut vererben.Wird diese Prüfung nach Anbau auf Niederungsmoorboden durchgeführt, ist eine noch strengere Auslese der Individuen mit geringer Verfärbung möglich.Das beschriebene Sekeltionsverfahren ermöglicht eine frühe Eliminierung des weniger wertvollen Zuchtmaterials.Mit 1 Abbildung