Three-dimensional imaging of a sawn surface: a comparison of confocal microscopy,scanning electron microscopy,and light microscopy combined with serial sectioning

The three-dimensional structure of a transverse sawn wood surface was investigated using several methods, to compare techniques, and to study the types of deformation in tracheids at the saw cut. A sample of spruce sapwood was cut with a fret saw across the grain. The transverse sawn surface was imaged by confocal microscopy, field emission scanning electron microscopy (FESEM), and by light microscopy combined with serial sectioning and three-dimensional (3D) reconstruction. Both confocal microscopy and FESEM were restricted to visualising the cut surface of the wood. However, serial sectioning was able to reveal the internal structure below the cut surface providing more information on the types of cell deformation present. The wood structure was deformed to depths of more than 600 μm below the surface with twisting, crushing and tearing deformations. Near the outer surface, gaps were formed between groups of tracheids where the cell walls had been torn away to form saw dust. The deformation tended to form groups of tracheids that were twisted relative to each other. Latewood was less distorted, forming a dense solid surface compared to the highly fibrous earlywood.     

Case–control risk factor study of methicillin-resistant Staphylococcus pseudintermedius (MRSP) infection in dogs and cats in Germany

Methicillin-resistant Staphylococcus pseudintermedius (MRSP) has emerged as a highly drug-resistant small animal veterinary pathogen. Although often isolated from outpatients in veterinary clinics, there is concern that MRSP follows a veterinary-hospital-associated epidemiology. This study's objective was to identify risk factors for MRSP infections in dogs and cats in Germany. Clinical isolates of MRSP cases (n = 150) and methicillin-susceptible S. pseudintermedius (MSSP) controls (n = 133) and their corresponding host signalment and medical data covering the six months prior to staphylococcal isolation were analysed by multivariable logistic regression. The identity of all MRSP isolates was confirmed through demonstration of S. intermedius-group specific nuc and mecA. In the final model, cats (compared to dogs, OR 18.5, 95% CI 1.8–188.0, P = 0.01), animals that had been hospitalised (OR 104.4, 95% CI 21.3–511.6, P < 0.001), or visited veterinary clinics more frequently (>10 visits OR 7.3, 95% CI 1.0–52.6, P = 0.049) and those that had received topical ear medication (OR 5.1, 95% CI 1.8–14.9, P = 0.003) or glucocorticoids (OR 22.5, 95% CI 7.0–72.6, P < 0.001) were at higher risk of MRSP infection, whereas S. pseudintermedius isolates from ears were more likely to belong to the MSSP-group (OR 0.09, 95% CI 0.03–0.34, P < 0.001). These results indicate an association of MRSP infection with veterinary clinic/hospital settings and possibly with chronic skin disease. There was an unexpected lack of association between MRSP and antimicrobial therapy; this requires further investigation but may indicate that MRSP is well adapted to canine skin with little need for selective pressure.     

Establishment of proliferative cell nuclear antigen gene as an internal reference gene for polymerase chain reaction of a wide range of archival and fresh mammalian tissues.

Polymerase chain reaction (PCR) from paraffin-embedded tissues provides a powerful tool to amplify DNA from a variety of recent and archival material. Because DNA from paraffin-embedded samples is more degraded than from fresh material, the amplification of reference genes is essential to exclude false-negative results. This study describes the use of the proliferative cell nuclear antigen (PCNA) gene as a reference gene in a range of animal species and in humans. The PCNA-PCR to amplify a fragment extending from exon 5 through exon 6 and including the intervening intron 6 gave a reproducible pattern, with a 280-base pair (bp) band from canine, equine, bovine, ovine, and caprine samples showing high sequence homology. Porcine, guinea pig, tiger, and lion samples, however, gave an additional fragment of approximately 197 bp. The whole intron 6 from these fragments is missing, possibly representing a pseudogene. In feline samples only the 197-bp fragment could be detected. This study shows that the PCNA gene is highly conserved across a broad range of animal species and is well suited as an internal control for PCR analysis in veterinary medicine.     

The potential aboveground carbon storage of north American forests

To assess the possibility of using C offset as a method of sequestering CO₂ produced by the burning of fossil fuels, it is necessary to have accurate estimates of C reservoirs and fluxes. Recent studies have shown that estimates of C commonly used in the past are too large, and this may lead to confusion about the global C budget. Field data used in recent estimates of present C storage for the North American boreal and eastern deciduous forest biomes were reanalyzed to estimate their maximum potential C storage. The original data were collected using a stratified two-stage cluster survey sampling design. The reanalysis suggests that the boreal forest and eastern deciduous forest could sequester possibly as little as 13.4% (3.0 Pg) and 18.5% (1.5 Pg), respectively, more C than they presently store. These estimates represent the potential increase in C storage under present conditions, if the study areas were allowed to revert back into forests.     

Analysis of 2-methylisoborneol and geosmin in catfish by microwave distillation--solid-phase microextraction

The semivolatile cyclic alcohols 2-methylisoborneol (MIB) and geosmin (GSM) impart muddy or musty flavors to water and food products. A rapid quantitative analytical technique has been developed whereby microwave distillation is used to remove the volatile organic compounds from a lipophilic matrix into an aqueous matrix. Solid-phase microextraction (MD-SPME) is then used to extract and concentrate the analytes, which are then desorbed in the injection port of a gas chromatograph/mass spectrometer (GC/MS) for analysis. Limits of detection are 0.01 microg/kg and limits of quantification are 0.1 microg/kg. MD-SPME is comparable in precision, requires no solvents, and is faster than current methods of analysis. This methodology allows detection of MIB and GSM at concentrations below human sensory thresholds in fish tissue.