Canine pododermatitis and idiopathic disease

Pododermatitis is a common inflammatory skin disease of dogs. As pedal lesions are reported in many canine dermatoses, a methodical series of diagnostic tests is required to establish the underlying aetiology. However, laboratory/ancillary investigations may prove unrewarding, prompting a diagnosis of idiopathic disease. Various hypotheses have been proposed to explain the pathogenesis of idiopathic pododermatitis including pedal conformation, trauma, immunosuppression, bacterial infection, furunculosis and dermal granuloma formation. Idiopathic pododermatitis accounts for 0.5% of all dermatology referrals to the authors' clinic. A sub-group within this population is characterised histopathologically by epidermal hyperplasia, hyperkeratosis, spongiosis, dermal oedema and perivascular aggregates of lymphocytes and plasma cells. The term lymphocytic-plasmacytic pododermatitis (LPP) has previously been proposed to reflect the histological appearance of such lesions. Affected dogs, although systemically well, characteristically have pruritus, erythema, swelling, pain and alopecia of the feet. Although non-responsive to antimicrobial therapy, antiparasitic agents and elimination diets, these dogs typically respond well to immunomodulatory therapy.     

Eighty Years of Grazing by Cattle Modifies Sagebrush and Bunchgrass Structure

Grazing by cattle is ubiquitous across the sagebrush steppe; however, little is known about its effects on sagebrush and native bunchgrass structure. Understanding the effects of long-term grazing on sagebrush and bunchgrass structure is important because sagebrush is a keystone species and bunchgrasses are the dominant herbaceous functional group in these communities. To investigate the effects of long-term grazing on sagebrush and bunchgrass structure, we compared nine grazing exclosures with nine adjacent rangelands that were grazed by cattle in southeast Oregon. Grazing was moderate utilization (30 ? 45%) with altering season of use and infrequent rest. Long-term grazing by cattle altered some structural aspects of bunchgrasses and sagebrush. Ungrazed bunchgrasses had larger dead centers in their crowns, as well as greater dead fuel depths below and above the crown level compared with grazed bunchgrasses. This accumulation of dry fuel near the meristematic tissue may increase the probability of fire-induced mortality during a wildfire. Bunchgrasses in the ungrazed treatment had more reproductive stems than those in the long-term grazed treatment. This suggests that seed production of bunchgrasses may be greater in ungrazed areas. Sagebrush height and longest canopy diameter were 15% and 20% greater in the ungrazed compared with the grazed treatment, respectively. However, the bottom of the sagebrush canopy was closer to the ground in the grazed compared with the ungrazed treatment, which may provide better hiding cover for ground-nesting avian species. Sagebrush basal stem diameter, number of stems, amount of dead material in the canopy, canopy gap size, and number of canopy gaps did not differ between ungrazed and grazed treatments. Moderate grazing does not appear to alter the competitive relationship between a generally unpalatable shrub and palatable bunchgrasses. Long-term, moderate grazing appears to have minimal effects to the structure of bunchgrasses and sagebrush, other than reducing the risk of bunchgrass mortality during a fire event.     

Effect of organic matter concentration on agricultural limestone dissolution in laboratory soil–water systems

Laboratory soil – water systems in which soil organic matter was increased by 0.0%, 0.5%, 1.0%, 2.0% and 4.0% by adding dry, chopped ryegrass (Lolium perenne) shoots to sandy soil containing 0.06% organic matter. Agricultural limestone was added to the systems, and pH, alkalinity and hardness of the water were monitored for 65 days. The pH, alkalinity and hardness increased with greater soil organic matter concentration. Amounts of carbon dioxide released by microbial respiration increased at the higher soil organic matter concentrations, and this resulted in more rapid and greater solubility of agricultural limestone. The results suggest that greater soil organic matter concentrations in ponds favour the rate and extent of agricultural limestone dissolution.     

Analysis of amino acid uptake and translocation in Arabidopsis with a low‐cost hydroponic system

In soils, amino acids may be an important source of nitrogen for plants, at least in those where organic matter is not quickly degraded. The physiology of uptake of amino acids by roots was mainly studied in the 70's and 80's, before genes encoding amino acid importers were cloned in the 90's. While two families of amino acid transporters have been identified, yielding a total of about 100 genes, the role of each member is yet to be elucidated. As a tool for studying the role of amino acid transporters from Arabidopsis we set up a new hydroponic system suitable for radioisotope use. This system enables reproducible amino acid uptake by roots and estimation of the transport to the shoots of the amino acid taken up. We show that the rates of glutamine (Gln) uptake by wild‐type roots and transfer to the shoots were linear, and that other tested amino acids were translocated to the shoots with lower efficiency than Gln. A T‐DNA insertion mutant for a Gln exporter was compared to the wild‐type plants. Gln uptake and transfer were similar in both genotypes, showing that the suppression of the exporter did not affect uptake or transfer of amino acids to the shoots. The main advantage of the hydroponic system presented here is that all the materials used to grow Arabidopsis are virtually free and can therefore be discarded, a useful feature when working with radioactivity.     

Managing Complex Problems in Rangeland Ecosystems

Management of rangelands, and natural resources in general, has become increasingly complex. There is an atmosphere of increasing expectations for conservation efforts associated with a variety of issues from water quality to endangered species. We argue that many current issues are complex by their nature, which influences how we approach them. We define a complex problem as one that varies in time and space. In other words, one answer may not be correct for all sites or during all years. For simple problems a generalized answer may be sufficient, and even for complex problems, general rules provide a good starting point. However, we suggest that it is important to distinguish between simple and complex problems. Several key obstacles emerge when considering complex natural resource problems, namely, 1) no single entity can handle all aspects of the problem and 2) significant knowledge gaps exist and will continue to exist into the future. We suggest that overcoming these obstacles will benefit from 1) a framework for effective partnerships and 2) a mechanism for continuous learning. Managing complex problems will require some combination of the following: 1) a process-based understanding of the problem (i.e., what causes variation in time and space), 2) adaptive management, and 3) effective coordination of research and management. There are many examples of organizations applying portions of these approaches to complex problems; however, it seems that in many cases the process has simply evolved in that direction rather than being a planned strategy. We suggest that as a profession we need to have a discussion about the nature of the problems we are addressing and how researchers and managers can jointly address these problems.     

A Technique for Estimating Riparian Root Production

Belowground plant biomass plays a critical role in the maintenance of riparian ecosystems and generally constitutes the majority of the total biomass on a site. Despite this importance, belowground dynamics of riparian plant species are not commonly investigated, in part because of difficulties of sampling in a belowground riparian environment. We investigated the field utility of a root-ingrowth sampling technique for measuring root production. We established four streamside sampling sites in southeastern Oregon, and randomly located four plots within each site. In each plot we established two 7.6-cm–diameter sand-filled ingrowth cores in September of 2004. In September of 2005 we harvested the cores with the use of a vacuum sampling technique in which a 5.1-cm–diameter camphored polyvinyl chloride casing was driven into the center of the root core and sand and root materials were suctioned out. Root-length density was determined by computer image analysis, and roots were dried and weighed to determine production by weight. Results indicate that root-length density averaged 7.2 (± 0.7) cm · cm^-3 across sites and root-production index was 356.7 (± 20.6) g · m^-2. Our index to root production by weight was consistent with previous estimates of annual root production reported in the literature. Our sampling technique proved to be a practical solution for root sampling in riparian environments, and helps overcome some of the difficulties in sequential coring of saturated soils. Use of any ingrowth core technique to index root production can potentially bias production estimates because of the artificial, root-free environment of the core. However, these biases should be consistent across sites, making ingrowth cores useful for determining differences between manipulative treatments.     

增加哺乳母猪日粮中L—赖氨酸的添加量

在低水平豆粕型母猪哺乳期饲料中添加合成赖氨酸以平衡日粮的营养水平,不会对母猪当前和以后的生产性能产生负面影响,虽然合成氨基酸的成本增加了,但整体生产成本能够下降。     

Direct observation and quantification of CO₂ binding within an amine-functionalized nanoporous solid

Understanding the molecular details of CO(2)-sorbent interactions is critical for the design of better carbon-capture systems. Here we report crystallographic resolution of CO(2) molecules and their binding domains in a metal-organic framework functionalized with amine groups. Accompanying computational studies that modeled the gas sorption isotherms, high heat of adsorption, and CO(2) lattice positions showed high agreement on all three fronts. The modeling apportioned specific binding interactions for each CO(2) molecule, including substantial cooperative binding effects among the guest molecules. The validation of the capacity of such simulations to accurately model molecular-scale binding bodes well for the theory-aided development of amine-based CO(2) sorbents. The analysis shows that the combination of appropriate pore size, strongly interacting amine functional groups, and the cooperative binding of CO(2) guest molecules is responsible for the low-pressure binding and large uptake of CO(2) in this sorbent material.