Nano-scale secondary ion mass spectrometry — A new analytical tool in biogeochemistry and soil ecology: A review article

Soils are structurally heterogeneous across a wide range of spatio-temporal scales. Consequently, external environmental conditions do not have a uniform effect throughout the soil, resulting in a large diversity of micro-habitats. It has been suggested that soil function can be studied without explicit consideration of such fine detail, but recent research has indicated that the micro-scale distribution of organisms may be of importance for a mechanistic understanding of many soil functions. Current techniques still lack the adequate sensitivity and resolution for data collection at the micro-scale, and the question ‘How important are various soil processes acting at different scales for ecological function?’ is therefore challenging to answer. The nano-scale secondary ion mass spectrometer (NanoSIMS) represents the latest generation of ion microprobes, which link high-resolution microscopy with isotopic analysis. The main advantage of NanoSIMS over other secondary ion mass spectrometers is its ability to operate at high mass resolution, whilst maintaining both excellent signal transmission and spatial resolution (down to 50 nm). NanoSIMS has been used previously in studies focussing on presolar materials from meteorites, in material science, biology, geology and mineralogy. Recently, the potential of NanoSIMS as a new tool in the study of biophysical interfaces in soils has been demonstrated. This paper describes the principles of NanoSIMS and discusses the potential of this tool to contribute to the field of biogeochemistry and soil ecology. Practical considerations (sample size and preparation, simultaneous collection of isotopes, mass resolution, isobaric interference and quantification of the isotopes of interest) are discussed. Adequate sample preparation, avoiding bias due to artefacts, and identification of regions-of-interest will be critical concerns if NanoSIMS is used as a new tool in biogeochemistry and soil ecology. Finally, we review the areas of research most likely to benefit from the high spatial and high mass resolution attainable with this new approach.     

MAGNETIC RESONANCE IMAGING OF THE NORMAL EYE AND ORBIT OF THE DOG AND CAT

Magnetic resonance (MR) images of the normal eye and orbit of the dog and cat were acquired. T1-weighted, proton-density, and T2-weighed images were obtained in the oblique dorsal, straight sagittal, and oblique sagittal planes. Signal intensity for the various orbital structures differed among the three resonance techniques. T1-weighted images provided the greatest contrast of the retrobulbar structures. T-1 weighted images also had the highest signal to noise ratio, thereby providing the best anatomic detail. Anatomic components of the globe, retrobulbar structures and ocular adnexa were easily seen in all MR sections. The oblique dorsal and oblique sagittal planes were superior for evaluating the optic nerve in its entirety.     

Analysis of the outer membrane proteins of Bacteroides nodosus, the causal organism of ovine footrot

Examination by SDS-PAGE of lithium acetate extracts of several strains of depiliated Bacteroides nodosus revealed 6 major outer membrane proteins (including pilin). The 5 membrane proteins exhibited approximate molecular weights of 75000, 50000, 38000, 34500 and 26500 whereas pilin had a MW of 17500 for the majority of strains. All proteins were accessible to lactoperoxidase-catalysed iodination and proteins 1, 2 and 5 were shown to be glycoproteins. Several attempts to isolate individual OMC proteins in pure form by selective solubilization and gel filtration were unsuccessful, but electroelution of individual outer membrane complex proteins resolved by SDS-PAGE provided sufficient quantities of antigen for immunization of sheep and for immunochemical analysis.     

An Asian ambrosia beetle Euwallacea fornicatus and its novel symbiotic fungus Fusarium sp. pose a serious threat to the Israeli avocado industry

The ambrosia beetle, Euwallacea fornicatus Eichhoff, was first recorded in Israel in 2009. The symbiotic fungus Fusarium sp., carried in mycacangia located in the anterior region of the female head, is responsible for the typical wilt symptoms inflicted on avocado (Persea americana Miller) trees. The beetle?Cfungus complex has become a serious threat to the future of the avocado industry in Israel.     

Mineralization of native soil organic matter is not regulated by the size,activity or composition of the soil microbial biomass—a new perspective

Soil organic matter is extensively humified; some fractions existing for more than 1000 years. The soil microbial biomass is surrounded by about 50 times its mass of soil organic matter, but can only metabolize it very slowly. Paradoxically, even if more than 90% of the soil microbial biomass is killed, the mineralization of soil organic matter proceeds at the same rate as in an unperturbed soil. Here we show that soil organic matter mineralization is independent of microbial biomass size, community structure or specific activity. We suggest that the rate limiting step is governed by abiological processes (which we term the Regulatory Gate hypothesis), which convert non-bioavailable soil organic matter into bioavailable soil organic matter, and cannot be affected by the microbial population. This work challenges one of the long held theories in soil microbiology proposed by Winogradsky, of the existence of autochthonous and zymogenous microbial populations. This has significant implications for our understanding of carbon mineralization in soils and the role of soil micro-organisms in the global carbon cycle. Here we describe experiments designed to determine if the Regulatory Gate operates. We conclude that there is sufficient experimental evidence for it to be offered as a working hypothesis.     

Effects of hyperbaric oxygen on full-thickness meshed sheet skin grafts applied to fresh and granulating wounds in horses

OBJECTIVE: To determine the effects of hyperbaric oxygen therapy (HBOT) on full-thickness skin grafts applied to fresh and granulating wounds of horses. ANIMALS: 6 horses. PROCEDURES: On day 0, two 4-cm-diameter circular sections of full-thickness skin were removed from each of 2 randomly selected limbs of each horse, and two 4-cm-diameter circular skin grafts were harvested from the pectoral region. A skin graft was applied to 1 randomly selected wound on each limb, leaving the 2 nongrafted wounds to heal by second intention. On day 7, 2 grafts were harvested from the pectoral region and applied to the granulating wounds, and wounds grafted on day 0 were biopsied. On day 14, 1 wound was created on each of the 2 unwounded limbs, and the wounds that were grafted on day 7 were biopsied. All 4 ungrafted wounds (ie, 2 fresh wounds and 2 wounds with 1-week-old granulation beds) were grafted. The horses then received HBOT for 1 hour daily at 23 PSI for 7 days. On day 21, the grafts applied on day 14 were biopsied. RESULTS: Histologic examination of biopsy specimens revealed that grafts treated with HBOT developed less granulation tissue, edema, and neovascularization, but more inflammation. The superficial portion of the graft was also less viable than the superficial portion of those not treated with HBOT. CONCLUSIONS AND CLINICAL RELEVANCE: The use of HBOT after full-thickness skin grafting of uncompromised fresh and granulating wounds of horses is not indicated.     

Application of ozone in grain processing

Ozone is an effective fumigant for insect killing, mycotoxin destruction and microbial inactivation which has a minimal or no effect on grain quality. Studies have demonstrated that ozone which is a natural agent, may offer unique advantages for grain processing along with addressing growing concerns over the use of harmful pesticides. This paper focuses on the efficacy of ozone for preservation of food grains and discusses the possible effects on product quality. Inactivation mechanisms for micro-organisms and mycotoxins are detailed. Critical intrinsic and extrinsic factors governing inactivation are discussed along with potential grain applications.     

Dysphagia as the primary clinical abnormality in two dogs with inflammatory myopathy

Two adult Boxers were evaluated because of chronic dysphagia of several years' duration. Serum creatine kinase activity was high in both dogs, but other hematologic or serum biochemical abnormalities were not detected. Esophagraphy revealed abnormalities of the cricopharyngeal phase of swallowing in both dogs, and electromyography of the pharyngeal and laryngeal muscles revealed complex repetitive discharges, positive sharp waves, and fibrillation potentials characteristic of primary myopathy or neuropathy. Because of the severity of their condition, both dogs were euthanatized. Histologically, mixed-cell infiltrates were seen in sections of the masseter and thyropharyngeal muscles. Results of indirect immunofluorescence staining for proteins associated with dystrophic myopathy were unremarkable, except for decreased staining for integrin alpha7. A diagnosis of chronic inflammatory myopathy was made. The clinical importance of reduced staining for integrin alpha7 could not be determined but was considered to be a result of the myopathy.