A fresh look into VO(salen) chemistry: synthesis, spectroscopy, electrochemistry and crystal structure of [VO(salen)(H2O)]Br · 0.5 CH3CN

The reaction of V^IVO(salen) with [Et₄N][SnBr₃] in air proceeds via an initial reduction to give a [V^III (salen)]⁺ intermediate, which is then oxidised to dark green [V^VO(salen)(H₂O)]Br, 1. As determined by X-ray crystallography, 1 in the solid state contains hexacoordinate vanadium. ⁵¹V NMR spectra indicate that dissociation of the aqua ligand occurs to give a pentacoordinated [V^VO(salen)] cation in methanol-d₄ solution, while in DMSO-d₆ solutions, coordination of the solvent occurs to give [V^VO(salen)(DMSO-d₆)]⁺. The colour of 1 can be accounted for by O_oxo → V^V and phenolate → V^V LMCTs. Results from this study have led to the re-assignment of LMCTs and V-N and V-O_phenolate stretching frequencies in the IR spectrum. Cyclic voltammetry of 1 indicates three redox processes. The first is typical of [VO(salen)]/[VO(salen)]⁺ couple and the other two are bromide oxidations.     

Identification of amyloidogenic proteins in the microbiomes of a rat Parkinson's disease model and wild‐type rats

Cross seeding between amyloidogenic proteins in the gut is receiving increasing attention as a possible mechanism for initiation or acceleration of amyloid formation by aggregation‐prone proteins such as αSN, which is central in the development of Parkinson''s disease (PD). This is particularly pertinent in view of the growing number of functional (i.e., benign and useful) amyloid proteins discovered in bacteria. Here we identify two amyloidogenic proteins, Pr12 and Pr17, in fecal matter from PD transgenic rats and their wild type counterparts, based on their stability against dissolution by formic acid (FA). Both proteins show robust aggregation into ThT‐positive aggregates that contain higher‐order β‐sheets and have a fibrillar morphology, indicative of amyloid proteins. In addition, Pr17 aggregates formed in vitro showed significant resistance against FA, suggesting an ability to form highly stable amyloid. Treatment with proteinase K revealed a protected core of approx. 9 kDa. Neither Pr12 nor Pr17, however, affected αSN aggregation in vitro. Thus, amyloidogenicity does not per se lead to an ability to cross‐seed fibrillation of αSN. Our results support the use of proteomics and FA to identify amyloidogenic protein in complex mixtures and suggests that there may be numerous functional amyloid proteins in microbiomes.     

Short-term changes in-stream macroinvertebrate communities following a severe fire in the Lake Tahoe basin,California

Rivers, lakes and wetlands are good examples of ecosystems that provide multiple, concurrent, services to mankind. Human society has often exploited these systems by enhancing one ecosystem service at the expense of another. Loch Leven, Scotland, UK, is a good example of this. Over the past 150 years, the lake has been subjected to hydrological modification, fish stocking and pollution control to improve the delivery of key goods and services. This study uses historical records to explore the results of these interventions on the ecosystem services that were targeted for improvement and the knock-on effects on other services provided by the lake. The results suggest that, when management changes are being considered to enhance particular ecosystem services, the potentially damaging effects on other ecosystem services should be taken into account. This requires a better understanding of the role of ecosystem function in delivering ecosystem services, and of the links between multiple ecosystem services, than is currently available. While further research is clearly needed, the value of long-term datasets in providing knowledge and understanding through ‘hindsight’ should not be underestimated. The study concludes that successful management actions are likely to be those that incorporate lessons learned from previous decisions.     

Untersuchungen zur Bestimmung des Geschlechts

Ohne Zusammenfassung     

DasHelodea-Blatt als Testobjekt zum Studium der Wirkung von Schädlingsbekämpfungsmitteln

Zusammenfassung Die Praxis der Schädlingsbekämpfung wird auf die Möglichkeit hingewiesen, durch stärkere Berücksichtigung protoplasmatischer Gedankengänge und Methoden der Lösung ihrer Probleme näher zu kommen.Auf der anderen Seite eröffnen sich der Protoplasmaforschung durch Berücksichtigung der auftauchenden Fragestellungen neue Wege der Erkenntnis.An einigen praktischen Beispielen wird die Arbeitsmöglichkeit auf diesem Gebiete gezeigt. DasHelodea- Blatt erwies sich als ein ausgezeichnetes Versuchsobjekt zum Studium der Wirkung einzelner Gifte und, innerhalb gewisser Grenzen, als ein gutes Testobjekt zum Vergleich verschiedener oder verschieden angewandter Schädlingsbekämpfungsmittel.Es wird die Abtötungskurve desHelodea-Blattes für Nikotin aufgestellt.Nikotin kann in charakteristischer Weise auf die Wanderung der Piastiden Einfluß haben (Brückenstellung der Plastiden).Eine ähnliche Kurve wird für Schwefelkalk gegeben. Unter gewissen Bedingungen geht mit der Zellvergiftung eine Schwärzung des gesamten Plasmaapparates, vor allem zuerst der Plastiden, einher.Für die Vergiftung mit Kupferkalk gelten besondere Voraussetzungen, auch hier dürfte sich dasHelodea-Blatt als Versuchsobjekt bewähren.