Effects of plant extracts on downy mildew of vine-Laboratory and field experiments

Extracts made from leaves, bark, flowers or roots of 23 different plant species using water, alcohol or acetone were tested against downy mildew of vine in laboratory, glasshouse and vineyards. Highest effects were found for Hedera helix (leaves in water), Quercus spec.(bark in alcohol), Primula veris (roots in water), Rhamnus frangula (roots in alcohol), Solidago spec (leaves in alcohol), Salix spec. (bark in water). Extracts of Rhamnus and Primula had significant curative effects (30 - 35%). In the laboratory and glasshouse test protective effects were much better (70- 90% reduction of infection) than the results in field experiments (30 - 40%). Single use of these extracts is insufficient for practical use in viticulture. The use in combinations with stone-meals and low doses of copper should be tested in future

Vergleich verschiedener Kupferformulierungen bei gleicher CU-Aufwandmenge gegen Rebenperonospora

Kupferhaltige Präparate sind bisher eine wichtige Basis für die Peronosporabekämpfung im ökologischen Anbau. Bereits sehr geringe Kupferaufwandmengen haben eine sehr gute Wirkung gegen Rebenperonospora (siehe Kast 1996). Nach dem derzeitigen Stand des Anhangs 2 der EU-Verordnung 2092/91 sind kupferhaltige Präparate allerdings nur noch bis zum 31.03.2002 zulässig. In Deutschland lauft die Zulassung aller Kupferpräparate Ende des Jahres 2000 aus. Inwieweit die Zulassungen verlängert werden können, ist zurzeit offen. Das Schwermetall Kupfer reichert sich bei kontinuierlicher Anwendung allmählich im Boden an und belastet insbesondere auch die Ökosysteme der Oberflächengewässer. Auch bei einer Verlängerung der Zulassungen muss es deshalb im Interesse des ökologischen Anbaus sein, mit möglichst geringen Kupferaufwandmengen auszukommen, um die unerwünschten ökologischen Auswirkungen möglichst gering zu halten. Ziel der vorliegenden Untersuchungen war es deshalb, zu prüfen, ob durch optimierte Formulierungen bei gleicher Kupferaufwandmenge ein besserer Effekt erzielt werden kann

Untersuchungen zur Wirksamkeit von Pflanzenextrakten gegen den Erreger des Falschen Mehltaus der Weinrebe (Plasmopara viticola)

Ziel der Untersuchungen war die Suche nach Naturstoffen, die im ökologischen Weinbau die Anwendung von Kupfer gegen Rebenperonospora ersetzen oder ergänzen könnten. Zu diesem Zweck wurden Extrakte von einheimischen Pflanzen (Pflanzenteilen) zunächst einem Laborscreening unterworfen und die erfolgreichsten Extrakte an Topfpflanzen und schließlich in zwei Freilandversuchen (2000 und 2001) angewandt. Die festgestellten Effekte der Pflanzenextrakte sind zwar signifikant, die im Freiland gefundene Wirkung ist aber für eine praktische Anwendung als Bekämpfungsmittel im ökologischen Weinbau zu gering. Sie wären allenfalls in Kombination z. B. mit Kupfer oder Gesteinsmehlen oder beim Anbau teilresistenter Reben nutzbar

First results with a spore trap for collecting infectious sporangia of downy mildew

Research Not

Survival of sporangia from Plasmopara viticola, the downy mildew of grapevine

Research NoteThe potential of aged sporangia from Plasmopara viticola to produce zoospores as a requirement to form new infections was determined. Sporangia were produced on potted grapevines and kept on the vines at 22 °C, 30 % r.h. or 22 °C, 60-80 % r.h., respectively. Under these conditions release of zoospores from sporangia could be observed microscopically until 7 d after outbreak of sporangia if liquid water was available. After suspending sporangia in water a first release of zoospores from fresh sporangia was observed after 30 min, from 3-7 d old sporangia not before 180 min. Sporangia kept under the above mentioned conditions were able to infect leaves for at least 9 d after outbreak

Effects of microflora composition in the phyllosphere on biological regulation of grapevine fungal diseases

Aqueous fermentation extracts of composted microbiologically active substrates reduced significantly the infestation of grapevine leaves with Plasmopara viticola under growth chamber conditions. Enhancement of efficacy was available through the enrichment of the extracts with nutrients - like sucrose and brewer's yeast - or with a natural surfactant (methylized cellulose). Studies on the microbial composition of the phyllosphere showed that the quantity of the total number of colony forming units, of yeasts/filametous fungi, of enterobacteria, of pseudomonads and of aerobic bacilli depends on the specific amendments to the extracts and on the microclimatic conditions. They ace responsible for the differences in efficiency of the various extracts against P. viticola. Appropriate investigations on the phyllosphere in a field experiment resulted in a different composition of the microflora, though the same combinations of extract amendments were used. This is caused by the varying environmental conditions. In spite of the changed microflora, the disease suppressing effects against Urcinula necator were preserved

Zum Einfluß der Stickstoffdüngung auf den Befall der Reben durch Phomopsis viticola SACC.

Effects of nitrogen supply on infection of grapevines by Phomopsis viticola SACC.The influence of nitrogen supply on the infection of grapevine cv. Kerner by Phomopsis viticola was tested in the field. In years favourable for fungus attack, the rate of infection increased when changing from the lowest N dose to the highest one

Tectonics of a K+ channel: The importance of the N-terminus for channel gating

AbstractThe small K+ channel Kcv represents the pore module of complex potassium channels. It was found that its gating can be modified by sensor domains, which are N-terminally coupled to the pore. This implies that the short N-terminus of the channel can transmit conformational changes from upstream sensors to the channel gates. To understand the functional role of the N-terminus in the context of the entire channel protein, we apply combinatorial screening of the mechanical coupling and long-range interactions in the Kcv potassium channel by reduced molecular models. The dynamics and mechanical connections in the channel complex show that the N-terminus is indeed mechanically connected to the pore domain. This includes a long rang coupling to the pore and the inner and outer transmembrane domains. Since the latter domains host the two gates of the channel, the data support the hypothesis that mechanical perturbation of the N-terminus can be transmitted to the channel gates. This effect is solely determined by the topology of the channel; sequence details only have an implicit effect on the coarse-grained dynamics via the fold and not through biochemical details at a smaller scale. This observation has important implications for engineering of synthetic channels on the basis of a K+ channel pore

Quantum–mechanical property prediction of solvated drug molecules: what have we learned from a decade of SAMPL blind prediction challenges?

Joint academic–industrial projects supporting drug discovery are frequently pursued to deploy and benchmark cutting-edge methodical developments from academia in a real-world industrial environment at different scales. The dimensionality of tasks ranges from small molecule physicochemical property assessment over protein–ligand interaction up to statistical analyses of biological data. This way, method development and usability both benefit from insights gained at both ends, when predictiveness and readiness of novel approaches are confirmed, but the pharmaceutical drug makers get early access to novel tools for the quality of drug products and benefit of patients. Quantum–mechanical and simulation methods particularly fall into this group of methods, as they require skills and expense in their development but also significant resources in their application, thus are comparatively slowly dripping into the realm of industrial use. Nevertheless, these physics-based methods are becoming more and more useful. Starting with a general overview of these and in particular quantum–mechanical methods for drug discovery we review a decade-long and ongoing collaboration between Sanofi and the Kast group focused on the application of the embedded cluster reference interaction site model (EC-RISM), a solvation model for quantum chemistry, to study small molecule chemistry in the context of joint participation in several SAMPL (Statistical Assessment of Modeling of Proteins and Ligands) blind prediction challenges. Starting with early application to tautomer equilibria in water (SAMPL2) the methodology was further developed to allow for challenge contributions related to predictions of distribution coefficients (SAMPL5) and acidity constants (SAMPL6) over the years. Particular emphasis is put on a frequently overlooked aspect of measuring the quality of models, namely the retrospective analysis of earlier datasets and predictions in light of more recent and advanced developments. We therefore demonstrate the performance of the current methodical state of the art as developed and optimized for the SAMPL6 pKa and octanol–water log P challenges when re-applied to the earlier SAMPL5 cyclohexane-water log D and SAMPL2 tautomer equilibria datasets. Systematic improvement is not consistently found throughout despite the similarity of the problem class, i.e. protonation reactions and phase distribution. Hence, it is possible to learn about hidden bias in model assessment, as results derived from more elaborate methods do not necessarily improve quantitative agreement. This indicates the role of chance or coincidence for model development on the one hand which allows for the identification of systematic error and opportunities toward improvement and reveals possible sources of experimental uncertainty on the other. These insights are particularly useful for further academia–industry collaborations, as both partners are then enabled to optimize both the computational and experimental settings for data generation

Chemically stabilized DNA barcodes for DNA-encoded chemistry

DNA-encoded compound libraries are a widely used small molecule screening technology. One important aim in library design is the coverage of chemical space through structurally diverse molecules. Yet, the chemical reactivity of native DNA barcodes limits the toolbox of reactions for library design. Substituting the chemically vulnerable purines by 7-deazaadenine, which exhibits tautomerization stability similar to natural adenine with respect to the formation of stable Watson–Crick pairs, yielded ligation-competent, amplifiable, and readable DNA barcodes for encoded chemistry with enhanced stability against protic acid- and metal ion-promoted depurination. The barcode stability allowed for straightforward translation of 16 exemplary reactions that included isocyanide multicomponent reactions, acid-promoted Pictet–Spengler and Biginelli reactions, and metal-promoted pyrazole syntheses on controlled pore glass-coupled barcodes for diverse DEL design. The Boc protective group of reaction products offered a convenient handle for encoded compound purification