Nitrogenase MoFe-protein at 1.16 A resolution: a central ligand in the FeMo-cofactor

A high-resolution crystallographic analysis of the nitrogenase MoFe-protein reveals a previously unrecognized ligand coordinated to six iron atoms in the center of the catalytically essential FeMo-cofactor. The electron density for this ligand is masked in structures with resolutions lower than 1.55 angstroms, owing to Fourier series termination ripples from the surrounding iron and sulfur atoms in the cofactor. The central atom completes an approximate tetrahedral coordination for the six iron atoms, instead of the trigonal coordination proposed on the basis of lower resolution structures. The crystallographic refinement at 1.16 angstrom resolution is consistent with this newly detected component being a light element, most plausibly nitrogen. The presence of a nitrogen atom in the cofactor would have important implications for the mechanism of dinitrogen reduction by nitrogenase.     

Precipitation or water capacity indices? An analysis of the benefits of alternative underlyings for index insurance

Eastern Germany is often hit by drought causing income risk for crop farmers. Index-based risk management instruments could help crop farmers to reduce their farm income risk. Such instruments have some important advantages over damage-based insurance, like e.g. less moral hazard and adverse selection. At the same time they typically have a high level of basis risk. Up to now, mainly precipitation-based weather derivatives have been discussed as an appropriate risk management instrument for farmers in Germany. As a potentially more effective alternative, we propose water capacity-based index insurance. In order to show the benefits of a precipitation-based and water capacity-based index insurance, several contract designs are compared. Using a whole farm risk program planning approach, we show that for an average agricultural producer in Eastern Germany water capacity-based index insurance offers greater benefits than precipitation-based index insurance.     

Turning back the tide of American mink invasion at an unprecedented scale through community participation and adaptive management

Successful eradications of harmful invasive species have been mostly confined to islands while control programs in mainland areas remain small, uncoordinated and vulnerable to recolonisation. To allow the recovery of threatened native species, innovative management strategies are required to remove invasives from large areas. We took an adaptive approach to achieve large scale eradication of invasive American mink in North East Scotland. The project was centred on the Cairngorms National Park (Scotland), with the primary aim of protecting endangered water vole populations. The project was initiated by scientists and supported and implemented through a partnership comprising a government agency, national park authority and local fisheries boards. Capitalising on the convergent interests of a diverse range of local stakeholders, we created a coordinated coalition of trained volunteers to detect and trap mink. Starting in montane headwaters, we systematically moved down river catchments, deploying mink rafts, an effective detection and trapping platform. Volunteers took increasing responsibility for raft monitoring and mink trapping as the project progressed. Within 3 years, the project removed 376 mink from 10570 km² with the involvement of 186 volunteers. Capture rate within sub-catchments increased with greater connectivity to mink in other sub-catchments and with proximity to the coast where there is more productive habitat. The main factor underpinning the success of this project was functional volunteer participation. The project is a reason for optimism that the tide of invasion can be rolled back on a large scale where the convergent interest of local communities can be harnessed.     

Use of a self-expanding metallic stent for the treatment of a urethral stricture in a young cat

A 4-month-old intact male domestic shorthair cat was evaluated for urinary outflow obstruction after several weeks of medical management for traumatic urethral rupture. Positive-contrast retrograde urethrography and anterograde cystoscopy performed 4 weeks after the initial urethral injury confirmed a stricture approximately 1cm distal to the bladder trigone at the site of the initial urethral tear. A self-expanding metallic urethral stent (SEMS) was placed under fluoroscopic guidance to relieve the urethral stricture and re-establish luminal patency. After stent placement, the cat was able to void urine normally with minimal urinary incontinence noted. This resolved several months post-stent placement. No known clinical complications persisted other than mild intermittent hematuria.     

ADAMTS17 mutation associated with primary lens luxation is widespread among breeds

Primary lens luxation (PLL) is a well-recognized, painful and potentially blinding inherited ocular condition in dogs. We screened PLL-affected dogs of 30 different breeds, to identify those which carried a previously described c.1473+1 G>A mutation in ADAMTS17 that is associated with PLL in Miniature Bull terriers, Lancashire Heelers, and Jack Russell terriers. This ADAMTS17 mutation was identified in PLL-affected dogs from 14 additional breeds. PLL-affected dogs from some breeds (most notably the Shar pei and the Brittany spaniel) did not carry the G1473+1A ADAMTS17 mutation, indicating they must suffer from a genetically distinct form of the condition. We also estimated the frequency of this ADAMTS17 mutation in some of the breeds. Our findings indicate the mutation segregates in a large number of different breeds of dog, many of which are terriers or breeds with terrier co-ancestry, but some of which have more diverse origins. Our results also indicate that the mutation is present at high frequency within most of the breeds in which it segregates. In the miniature bull terrier breed estimates of mutation frequency ranged from 0.27 to 0.39, corresponding to 7.3-15.2% PLL-affected dogs in this breed. We also identified an increased risk of PLL associated with heterozygosity at ADAMTS17, suggesting that carriers carry a low risk of developing PLL.     

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Using metabolic profiling to assess plant-pathogen interactions: an example using rice (<Emphasis Type="Italic">Oryza sativa)</Emphasis> and the blast pathogen <Emphasis Type="Italic">Magnaporthe grisea</Emphasis>

A metabolomics based approach has been used to study the infection of the Hwacheong rice cultivar (Oryza sativa L. cv. Hwacheong) with compatible (KJ201) and incompatible (KJ401) strains of the rice blast fungal pathogen Magnaporthe grisea. The metabolic response of the rice plants to each strain was assessed 0, 6, 12, 24, 36, and 48 h post inoculation. Nuclear Magnetic Resonance (NMR) spectroscopy and Gas and Liquid Chromatography Tandem Mass spectrometry (GC/LC-MS/MS) were used to study both aqueous and organic phase metabolites, collectively resulting in the identification of 93 compounds. Clear metabolic profiles were observed at each time point but there were no significant differences in the metabolic response elicited by each pathogen strain until 24 h post inoculation. The largest change was found to be in alanine, which was ~30% (±9%) higher in the leaves from the compatible, compared to the resistant, plants. Together with several other metabolites (malate, glutamine, proline, cinnamate and an unknown sugar) alanine exhibited a good correlation between time of fungal penetration into the leaf and the divergence of metabolite profiles in each interaction. The results indicate both that a wide range of metabolites can be identified in rice leaves and that metabolomics has potential for the study of biochemical changes in plant-pathogen interactions.     

Spatial variability of O layer thickness and humus forms under different pine beech–forest transformation stages in NE Germany

Spatial variability of humus layer (O layer) thicknesses can have important impacts upon soil water dynamics, nutrient storage and availability, as well as plant growth. The purpose of the present study was to elucidate the impact of forest‐transformation practices on the spatial variability of O layer thicknesses. The study focused on the Kahlenberg forest area (NE Germany) with stands of Scots pine (Pinus sylvestris) and European beech (Fagus sylvatica) of different age structures that form a transformation chronosequence from pure Scots pine stands towards pure European beech stands. Topsoil profiles including both, the O layer and the uppermost humic mineral soil horizon were excavated at intervals of 0.4 m along 15–20 m long transects, and spatial variability of O layer thicknesses was quantified by variogram analysis. The correlation lengths of total O layer thickness increased in the sequence consisting of pure pine stand (3.1 m) → older mixed stand (3.7 m) → pure beech stand (4.5 m), with the exception of the younger mixed stand, for which no correlation lengths of total O layer thickness could be determined. The degree of spatial correlation, i.e., the percentage of the total variance which can be described by variograms, was highest for the two monospecies stands, whereas this percentage was distinctly lower for the two mixed stands. A similar minimum for the two mixed stands was observed for the correlation lengths of the Oh horizon. These results suggest that the spatial structures of forest‐transformation stands may be interpreted in terms of a disturbance (in the form of the underplanting of beech trees). After this disturbance, the forest ecosystem requires at least 100 y to again reach relative equilibrium. These findings are in line with the results of other soil‐related investigations at these sites.     

Detection of potentially allergenic hazelnut (Corylus avellana) residues in food: a comparative study with DNA PCR-ELISA and protein sandwich-ELISA

Allergen detection is of increasing interest for food labeling purposes. A comparative study with a commercial hazelnut-specific PCR-ELISA and a sandwich-type ELISA detecting hazelnut protein was performed to investigate to what extent immunochemical and DNA-based techniques would correlate in the detection of trace amounts of potentially allergenic hazelnut residues. Both methods were highly sensitive and allowed the detection of even <10 ppm of hazelnut in complex food matrixes. The protein-ELISA was highly specific for hazelnut. However, some foods could lead to false-positive results at the 10 ppm level. The PCR-ELISA did not show any cross-reactions with non-hazelnut foods, thus reducing the probability of having false positives at the trace level. Forty-one commercial food products with and without hazelnut components on their labels were analyzed for the presence of hazelnut. Of the 27 products in which hazelnut components were detected, two samples were not identified by the protein-ELISA, and only one sample, namely one white chocolate having <1 ppm of hazelnut protein, was not detected by PCR-ELISA. The good correlation of the results of PCR-ELISA and protein-ELISA suggested that both PCR-based and immunochemical techniques are suitable for reliable detection of potentially allergenic hazelnut residues in foods at the trace level.