Impact of bovine urine deposition on soil microbial activity,biomass, and community structure

Nitrogen (N) from urine excreted by grazing animals can be transformed into N compounds that have detrimental effects on the environment. These include nitrate, which can cause eutrophication of waterways, and nitrous oxide, which is a greenhouse gas. Soil microbes mediate all of these N transformations, but the impact of urine on microbes and how initial soil conditions and urine chemical composition alter their responses to urine are not well understood. This study aimed to determine how soil inorganic N pools, nitrous oxide fluxes, soil microbial activity, biomass, and the community structure of bacteria containing amoA (nitrifiers), nirK, and nirS (denitrifiers) genes responded to the addition of urine over time. Bovine urine containing either a high (15.0 g K⁺ l^?1) or low salt content (10.4 g K⁺ l^?1) was added to soil cores at either low or high moisture content (hereafter termed dry and wet soil respectively; 35% or 70% water-filled pore space after the addition of urine). Changes in soil conditions, inorganic N pools, nitrous oxide fluxes, and the soil microbial community were then measured 1, 3, 8, 15, 29 and 44 days after urine addition. Urine addition increased soil ammonium concentrations by up to 2 mg g d.w.^?1, soil pH by up to 2.7 units, and electrical conductivity (EC) by 1.0 and 1.6 dS m^?1 in the low and high salt urine treatments respectively. In response, nitrate accumulation and nitrous oxide fluxes were lower in dry compared to wet urine-amended soils and slightly lower in high compared to low salt urine-amended soils. Nitrite concentrations were elevated (>3 μg g d.w.^?1) for at least 15 days after urine addition in wet urine-amended soils, but were only this high in the dry urine-amended soils for 1 day after the addition of urine. Microbial biomass was reduced by up to half in the wet urine-amended soils, but was largely unaffected in the dry urine-amended soils. Urine addition affected the community structure of ammonia-oxidising and nitrite-reducing bacteria; this response was also stronger and more persistent in wet than in dry urine-amended soils. Overall, the changes in soil conditions caused by the addition of urine interacted to influence microbial responses, indicating that the effect of urine on soil microbes is likely to be context-dependent.     

Landscape analysis and tsunami damage in Aceh: comment on Iverson and Prasad (2007)

Data presented in Iverson and Prasad (2007), Using landscape analysis to assess and model tsunami damage in Aceh province, Sumatra. Landscape Ecology 22: 323–331 do not justify their conclusion that tree belts provided an effective defence against the Indian Ocean tsunami in Aceh, Indonesia. The mitigation hypothesis is not explicitly tested, and their modelling approach to predict areas susceptible to tsunami damage ignores many variables known to be important in the area studied.     

Diffuse cylindrical bronchiectasis due to eosinophilic bronchopneumopathy in a dog

A miniature pinscher-cross was evaluated for chronic coughing. Computed tomography and bronchoscopy revealed severe, diffuse, cylindrical bronchiectasis secondary to eosinophilic bronchopneumopathy. Computed tomography is the gold standard for diagnosis of bronchiectasis in humans, and should be further investigated in dogs as a means of characterizing severity and pattern of disease.     

Asymmetric scattering of polarized electrons by organized organic films of chiral molecules

Electron transmission experiments demonstrate a large asymmetry in the scattering probability of polarized electrons by thin organized films of chiral molecules. This large asymmetry results from the interaction of the electron's wavefunction with many scatterers (molecules) in the organized monolayer structure and represents a manifestation of quantum interference on the scale of supramolecular lengths.     

Lymphoplasmacytic gingivitis in a cat

A 12-year-old male neutered short haired cat was presented due to difficulty eating and pawing at the face. Examination revealed severe gingivitis and stomatitis throughout the oral cavity. Gingival biopsy provided a diagnosis of lymphoplasmacytic stomatitis. Extraction of all premolars and molars resulted in elimination of all clinical signs.