Performance of nitrification inhibitors with different nitrogen fertilizers and soil textures

Nitrification inhibitors (NIs), DCD (dicyandiamide), and DMPP (3,4‐dimethylpyrazole phosphate), in combination with urea (UR) and ammonium sulfate nitrate (ASN) fertilizers were studied under contrasting soil textures (sand, loam, and clay) from cultivated soils collected in Brazil and Germany. Soil samples were incubated over 50 days and the content of ammonium ( ), nitrate ( ), and soil pH were measured periodically. Applied NIs delayed the nitrification process across all soil textures. Correlation analysis indicated that combining ASN with NIs resulted in higher content and efficiency in delaying the nitrification process with high N‐conversion rate (r = –0.82). The combination of ASN+ DMPP increased the efficiency of the N‐conversion rate (r = –0.86) due to H⁺ release in soil, while UR+DCD (r = –0.50) had an efficiency of the N‐conversion rate similar to UR (r = –0.42). All the NIs had a better performance in reducing formation in sandy soils as compared to the loam and clay textured soils. Use of DMPP with an N fertilizer results in a soil pH decrease and can be an option to increase the efficiency of the N‐conversion rate, reducing N losses in soil. Overall, our results suggest that NIs have a better performance in reducing formation in sandy soils as compared to that of the loam and clay textured soils. Use of DMPP with ASN results in a soil pH decrease and can be an option to reduce N losses in soil.     

Molecular epidemiology of avian pathogenic Escherichia coli (APEC) isolated from colisepticemia in poultry

The molecular biology and epidemiology of 150 avian pathogenic Escherichia coli strains (APEC) isolated from septicemic poultry in Germany was investigated by serotyping, pulsed field gel electrophoresis (PFGE), and polymerase chain reaction (PCR). Only 49.6% of the isolates could be grouped to serogroups O1, O2, and O78. Macrorestriction analyses data revealed two large clonal groups (clusters I and II) among the APEC strains with a similarity of 60.9% to each other. An association between restriction pattern and serogroup or origin of the strains was only present in a few subgroups of each clusters I and II, but was not evident. In contrast, our data revealed distinct combinations of virulence-associated genes in that 51.2% of the O2-strains harboured a combination of the genes fyuA, irp2, iucD, tsh, vat, fimC, and colV and 36.4% of the O78-strains possessed the same gene combination with exception of vat. With 34 different gene combinations the non-O1, -O2, -O78 isolates revealed a higher variability in their virulence gene pattern than O1-, O2-, and O78-strains with 6, 13, and 9 patterns, respectively. Our data indicate only a limited association between the virulence gene pattern and the serogroup of APEC strains and question the sensitivity of O-typing for APEC identification without the application of further diagnostic tools. Although a limited number of APEC clones exist, horizontal gene transfer seems to be common in these pathogens. These findings strengthen further research on the population structure of APEC and may be the reason for the lack of clear definition of this common E. coli pathotype.     

Appearance and incidence of sacroiliac joint disease in ventrodorsal radiographs of the canine pelvis

Ventrodorsal (VD) radiographs of cadaveric pelves of large and giant breeds (n = 40) and of the corresponding bone specimens were made. Gross changes seen in the specimens were marked with metal wire or radiopaque paint to relate radiographic changes to the postmortem appearance of degenerative sacroiliac (SI) joint lesions. Two positioning techniques were used, resulting in two radiographs for each specimen. The techniques used were: (1) pulling the pelvic limbs caudally, with gentle traction producing a view of the sacrum in almost parallel alignment between the sacrum and the X-ray film (we have termed this a "central SI view") and (2) pulling the pelvic limbs caudally with greater traction than above, resulting in maximal inclination of the sacrum with respect to the X-ray film (we have termed this an "angled SI view"). Lesions of the supportive soft connective tissue could be imaged on the central and angled SI views, whereas angled SI views allowed better identification of lesions of the synovial SI joint. The insights gained in the above study were then used in a retrospective examination of 145 routine ventrodorsal radiographs of the pelvis (i.e., 290 sacroiliac joints) to determine the incidence of degenerative changes of the SI joint in large dogs. The lesions most commonly observed were calcification of the supportive soft connective tissue (n = 184/290), whereas lesions of the synovial SI joint were less frequent (n = 86/290). The degree of central or angled projection obtained in standard ventrodorsal radiographs was noted to be significantly (P < 0.05) associated with age, body conformation, anesthetic status, and the presence of spondylosis deformans at the lumbosacral junction. In contrast, SI joint disease and the gender of the animal did not affect the SI view achieved in VD radiographs.     

Unstable endobronchial intubation in a cat undergoing tracheal laceration repair

A peri-carinal tracheal laceration was produced in a 11-year-old cat during tracheal intubation. Before reconstructive surgery began, the leak was bypassed with an endobronchial tube positioned using endoscopy and direct vision. However, single-lung ventilation could not be sustained because the tube became dislodged and could not be repositioned. Consequently, surgery was completed with periods of intermittent apnoea interspersed with manually controlled hyperventilation. Cardiovascular variables were stable during anaesthesia and no signs of hypoxia were detected. The difficulties in maintaining endobronchial tube position resulted from the animal's small size relative to the dimensions of the endotracheal tube.     

Hydraulic and mechanical properties of young Norway spruce clones related to growth and wood structure

Stem segments of eight five-year-old Norway spruce (Picea abies (L.) Karst.) clones differing in growth characteristics were tested for maximum specific hydraulic conductivity (k(s100)), vulnerability to cavitation and behavior under mechanical stress. The vulnerability of the clones to cavitation was assessed by measuring the applied air pressure required to cause 12 and 50% loss of conductivity (Psi(12), Psi(50)) and the percent loss of conductivity at 4 MPa applied air pressure (PLC(4MPa)). The bending strength and stiffness and the axial compression strength and stiffness of the same stem segments were measured to characterize wood mechanical properties. Growth ring width, wood density, latewood percentage, lumen diameter, cell wall thickness, tracheid length and pit dimensions of earlywood cells, spiral grain and microfibril angles were examined to identify structure-function relationships. High k(s100) was strongly and positively related to spiral grain angle, which corresponded positively to tracheid length and pit dimensions. Spiral grain may reduce flow resistance of the bordered pits of the first earlywood tracheids, which are characterized by rounded tips and an equal distribution of pits along the entire length. Wood density was unrelated to hydraulic vulnerability parameters. Traits associated with higher hydraulic vulnerability were long tracheids, high latewood percentage and thick earlywood cell walls. The positive relationship between earlywood cell wall thickness and vulnerability to cavitation suggest that air seeding through the margo of bordered pits may occur in earlywood. There was a positive phenotypic and genotypic relationship between k(s100) and PLC(4MPa), and both parameters were positively related to tree growth rate. Variability in mechanical properties depended mostly on wood density, but also on the amount of compression wood. Accordingly, hydraulic conductivity and mechanical strength or stiffness showed no tradeoff.     

Impact of correlation between pesticide parameters on estimates of environmental exposure

Monte Carlo techniques are increasingly used in pesticide exposure modelling to evaluate the uncertainty in predictions arising from uncertainty in input parameters and to estimate the confidence that should be assigned to modelling results. The approach typically involves running a deterministic model repeatedly for a large number of input values sampled from statistical distributions. A key decision in setting up a probabilistic analysis is whether there is correlation between any of the inputs to the analysis. Pesticide properties are often the most sensitive in exposure assessment. Analysis of the literature demonstrated that there are examples of both positive and negative correlation between the sorption and degradation behaviour of a pesticide, but that general trends are not apparent at present. The inclusion of even weak correlation between sorption and degradation was found to greatly influence a probabilistic analysis of leaching through soil. Correlation will reduce the predicted extent of leaching for pesticides, and it is recommended to set the correlation to zero unless the experimental data support an alternative assumption (i.e. where the correlation is statistically significant (P 相似文献   

Pre- and postinvasion defenses both contribute to nonhost resistance in Arabidopsis

Nonhost resistance describes the immunity of an entire plant species against nonadapted pathogen species. We report that Arabidopsis PEN2 restricts pathogen entry of two ascomycete powdery mildew fungi that in nature colonize grass and pea species. The PEN2 glycosyl hydrolase localizes to peroxisomes and acts as a component of an inducible preinvasion resistance mechanism. Postinvasion fungal growth is blocked by a separate resistance layer requiring the EDS1-PAD4-SAG101 signaling complex, which is known to function in basal and resistance (R) gene-triggered immunity. Concurrent impairment of pre- and postinvasion resistance renders Arabidopsis a host for both nonadapted fungi.     

Magnetism on the angrite parent body and the early differentiation of planetesimals

Angrites are among the oldest known pristine basaltic meteorites and record the earliest stages of planet formation and differentiation. Our paleomagnetic analysis of three angrites found that they record a past magnetic field of approximately 10 microteslas on the angrite parent body extending from 4564 to at least 4558 million years ago. Because the angrite paleomagnetic record extends beyond the expected lifetime of the early circumstellar disk, these paleofields were probably generated internally on the angrite parent body, possibly by an early dynamo in a rapidly formed metallic core.