Infection conditions for Neofabraea perennans and Phacidiopycnis washingtonensis on developing apple fruit in the orchard

European Journal of Plant Pathology - In Northern Germany, a major share of postharvest losses of apple fruit is due to preharvest infections by pathogenic fungi. Little is known about their...     

Acylated 1,3-Aminopropanols as Repellents against Bloodsucking Arthropods

Starting from a set of known repellent compounds, a general structural framework with high probability for repellent activity was developed by molecular modelling techniques. Synthesis, structure–biological activity relationships of acylated 1,3-aminopropanols on the yellow fever mosquito Aedes aegypti and the properties and activity of the new development candidate compound KBR 3023 on Ae. aegypti, the malaria mosquito Anopheles stephensi, the common house mosquito Culex quinquefasciatus and the stable fly Stomoxys calcitrans are described. The sensory effect of KBR 3023 and deet has been studied in behavioural and neurophysiological investigations on Ae. aegypti and the American cockroach Periplaneta americana. The compounds clearly reduce or even eliminate the approach behaviour towards attractants like host odours or sexual pheromones. Electrophysiological studies on the insects' olfactory receptor organs reveal that certain cell types, which are not involved in perception of the attractive odorants, respond to deet and/or KBR 3023. As soon as one of the compounds is presented together with an attractant, a new input is active in the brain, which adds to the input from other receptors activated by the attractant. This new overall pattern clearly differs from that elicited by the attractant, so that the insect is no longer able to detect the latter. The specificity and mode of action of KBR 3023 was investigated by experiments exploring second-messenger responses elicited in antennal preparations of male P. americana. KBR 3023 induced a rapid increase in the concentration of inositol triphosphate in a dose-dependent and tissue-specific manner; other second-messenger systems were not affected. These observations suggest that KBR 3023 may act via subsets of G-protein-coupled receptors in sensory neurones.     

Oscillatory thermomechanical instability of an ultrathin catalyst

Because of the small thermal capacity of ultrathin ( approximately 200 nanometers) metal single crystals, it is possible to explore the coupling of catalytic and thermal action at low pressures. We analyzed a chemothermomechanical instability in this regime, in which catalytic reaction kinetics interact with heat transfer and mechanical buckling to create oscillations. These interacting components are separated and explored through experimentation, mathematical modeling, and scientific computation, and an explanation of the phenomenon emerges from their synthesis.     

Ice record of delta13C for atmospheric CH4 across the Younger Dryas-Preboreal transition

We report atmospheric methane carbon isotope ratios (delta13CH4) from the Western Greenland ice margin spanning the Younger Dryas-to-Preboreal (YD-PB) transition. Over the recorded approximately 800 years, delta13CH4 was around -46 per mil (per thousand); that is, approximately 1 per thousand higher than in the modern atmosphere and approximately 5.5 per thousand higher than would be expected from budgets without 13C-rich anthropogenic emissions. This requires higher natural 13C-rich emissions or stronger sink fractionation than conventionally assumed. Constant delta13CH4 during the rise in methane concentration at the YD-PB transition is consistent with additional emissions from tropical wetlands, or aerobic plant CH4 production, or with a multisource scenario. A marine clathrate source is unlikely.     

Experimental infection of wild boar and domestic pigs with a foot and mouth disease virus strain detected in the southeast of Bulgaria in December of 2010

Foot and mouth disease (FMD) was detected in a wild boar in Southeastern Bulgaria in December 2010. The occurrence and spread of the disease in wild cloven-hoofed animals may pose an unexpected and significant threat to FMD virus (FMDV)-free areas within and outside the European Union. So far, only one well documented experimental infection with FMD in wild boar has been published. In order to obtain more epidemiologically relevant data regarding the disease in wild boar we conducted an experiment with the 2010 Bulgarian FMDV type O isolate. Two young wild boar were challenged while two domestic pigs and two additional wild boar served as contact controls. While the domestic pigs developed severe clinical signs of FMD, the wild boar showed relatively mild course of the disease. Viremia started in contact wild boar 2 days post exposure (DPE) and lasted until 6 DPE. The virus shedding lasted until 9 DPE. On 27 DPE, when the animals were slaughtered, viral RNA was detected in lymphoid tissues and oropharyngeal fluid but no virus could be isolated. Commercial ELISAs and virus neutralisation tests detected antibodies against FMDV on 8 or 6 DPE, respectively. The data of the present study will help to understand FMD in wild boar populations and can be used in models to evaluate the potential role of wild boar in FMD epidemiology.     

Beryllium effects on potatoes and oats in acid soil

The most likely means of Be entry into the food chain would appear to be via root, tuber, and forage crops grown on acid soils. Potatoes (Solanum tuberosum) and oats (Avena sativa) were grown in greenhouse pots of a strongly acid soil treated with 0 to 300 ppm Be and 0 to 1000 ppm CaC0₃. Germination and yield decreased, and plant Be content increased, with increasing soil Be content. The Be content of the potato tubers appeared to be low and unaffected by the soil Be content. Liming the soil and increasing the time between Be contamination and crop planting lessened the effect of Be.     

A diarylquinoline drug active on the ATP synthase of Mycobacterium tuberculosis

The incidence of tuberculosis has been increasing substantially on a worldwide basis over the past decade, but no tuberculosis-specific drugs have been discovered in 40 years. We identified a diarylquinoline, R207910, that potently inhibits both drug-sensitive and drug-resistant Mycobacterium tuberculosis in vitro (minimum inhibitory concentration 0.06 mug/ml). In mice, R207910 exceeded the bactericidal activities of isoniazid and rifampin by at least 1 log unit. Substitution of drugs included in the World Health Organization's first-line tuberculosis treatment regimen (rifampin, isoniazid, and pyrazinamide) with R207910 accelerated bactericidal activity, leading to complete culture conversion after 2 months of treatment in some combinations. A single dose of R207910 inhibited mycobacterial growth for 1 week. Plasma levels associated with efficacy in mice were well tolerated in healthy human volunteers. Mutants selected in vitro suggest that the drug targets the proton pump of adenosine triphosphate (ATP) synthase.