Microbial communities and their relevance for ecosystem models: Decomposition as a case study

Soil microbial communities are so vastly diverse that complex interactions, which alter ecosystem functions, may occur among microbial species and functional groups. In this review, we explore the empirical evidence for situations when shifts in the community structure of microbes would elicit a change in ecosystem process rates, specifically decomposition, even when microbial biomass remains constant. In particular, we are interested in a subset of these scenarios in which knowledge of microbial community structure would improve model predictions for ecosystem functions. Results from microcosm and field studies indicate that microbial species diversity, functional group diversity, and community composition can all influence ecosystem process rates. The underlying mechanisms that may elicit changes in ecosystem functions from shifts in microbial community structure include evolutionary constraints on microbial trait adaptation, trait correlations, dispersal limitation, and species interactions. The extent of microbial diversity in soils is not known, so it is presently not possible to model all scenarios of microbial community structure shifts. However, by incorporating documented patterns in functional groups that are relevant for a particular ecosystem process and potential relationships between microbial phylogeny and function, the predictive power of process models will be significantly improved. The inclusion of this information into process models is critical for predicting and understanding how ecosystem functions may shift in response to global change.     

Synthesis,mechanism of action,and QSAR of herbicidal 3-substituted-2-aryl-4,5,6,7-tetrahydroindazoles

A factorially designed set of 3-substituted 2-aryl-4,5,6,7-tetrahydroindazoles was synthesized and their herbicidal properties were evaluated using regression analysis. For optimal activity, the substituent at position 3 should be neither strongly hydrophobic nor hydrophilic and should have a small minimum radius. A study of the mechanism of action indicated that the tetrahydroindazoles are inhibitors of the enzyme protoporphyrinogen oxidase.     

Rehabilitation for the neurologic patient.

A properly designed rehabilitation program should be an important component of the treatment plan of animals with neurologic disease.Such a program should be designed in conjunction with appropriate treatment of the underlying problem and after special consideration of the origin of the neurologic problem, the severity of the signs, the cause of the signs, their anticipated progression, and the needs of the owner and the pet. This article describes the pathophysiology of injury and recovery in the central and peripheral nervous systems, assessment of the neurologic patient, data on the prognosis and expected course of recovery for a variety of different diseases, and rehabilitation exercises appropriate for neurologic patients.     

Use of IMEX SK-circular external fixator hybrid constructs for fracture stabilization in dogs and cats

Complex long-bone fractures with short juxta-articular fracture segments can be difficult to manage. Recently, IMEX Veterinary, Inc., began producing titanium hybrid rods that can be secured to ring components of the IMEX circular external skeletal fixation system to create SK-circular hybrids. In this case series, SK-circular hybrids were used to stabilize long-bone fractures (two femoral, one humeral, and three tibial fractures) with short distal bone segments in three dogs and three cats with body weights ranging from 1.9 to 15 kg (mean, 6.7 kg; median, 5.4 kg). Although three cases required surgical revision, animals ambulated well and all fractures obtained union. Time to radiographic union ranged from 62 to 137 days (mean, 90 days; median, 84 days). The functional outcome was considered excellent in all six cases.     

Atypical pectus excavatum in two Welsh terrier littermates

Two six-week-old intact Welsh terrier littermates, a male and a female, were presented for congenital ventral thoracic wall deformities characterised by noticeable funnel-like depressions of the cranial sternum associated with inversion of the rib cage. No exercise intolerance or cardiac murmurs were noted. Thoracic radiographic examination revealed a significant dorsal deviation of the first to the fifth sternebrae. At 12 weeks of age, the thoracic depressions had improved markedly in both puppies. Thoracic radiography to reassess the sternal deviation was at this stage within normal limits, demonstrating complete radiographic resolution of the sternal deformity.     

Response of high-rise and base-isolated buildings to a hypothetical mw 7.0 blind thrust earthquake

High-rise flexible-frame buildings are commonly considered to be resistant to shaking from the largest earthquakes. In addition, base isolation has become increasingly popular for critical buildings that should still function after an earthquake. How will these two types of buildings perform if a large earthquake occurs beneath a metropolitan area? To answer this question, we simulated the near-source ground motions of a M(w) 7.0 thrust earthquake and then mathematically modeled the response of a 20-story steel-frame building and a 3-story base-isolated building. The synthesized ground motions were characterized by large displacement pulses (up to 2 meters) and large ground velocities. These ground motions caused large deformation and possible collapse of the frame building, and they required exceptional measures in the design of the base-isolated building if it was to remain functional.     

Aspects of the productivity of forage legumes in Northern Europe

A database on the productivity of red clover (Trifolium pratense), white clover (Trifolium repens), lucerne (Medicago sativa), lotus (Lotus corniculatus) and galega (Galega orientalis) was compiled. It contains 1852 observations for 330 trials at fifty‐three sites in eight north European countries for the period from 1977 to 1997. The database includes information on climatic and site characteristics, as well as agronomic data, collated into four smaller data sets. This has permitted four key agronomic issues to be examined, namely: (i) how yield for a given variety varies under different environmental conditions; (ii) how the relative performance of different species varies between sites; (iii) how persistence varies between species and sites; and (iv) what the nature of the relationship is between varieties, yield and sites within a species? Cluster analysis revealed that geographical location had a fairly strong influence on yield. Across sites for an individual variety, the cumulative day‐degrees during the regrowth period had the highest correlation with total yield. In terms of the relative performance of different forage legume species across sites, red clover and lucerne were estimated to yield about 2·5 t DM ha^?1 more than white clover and there was a significant impact of cumulative day‐degrees during regrowth and the age of ley on the total yield. It was found that red clover had the lowest persistence index and lucerne the highest. As regards the interaction between yield, varieties and sites, the length of growth period and the age of the ley explained two‐thirds of the variation in total yield in red clover varieties of contrasting maturity types.     

SONOGRAPHIC AND SCINTIGRAPHIC EVALUATION OF ACUTE RENAL ALLOGRAFT REJECTION IN CATS

The sonographic features of acute renal allograft rejection in humans and dogs are manifested by increase in renal cross-sectional area and reduction in renal cortical blood flow. These changes have not been investigated in cats. The objectives of this study were to evaluate sonographic and scintigraphic changes during acute renal allograft rejection in cats. Eight SPF, intact, adult, male cats received heterotopic renal allotransplantations. Immunosuppressive doses of cyclosporine and prednisolone were administered for 14 days and then discontinued to allow acute allograft rejection to occur. Serial measurements of renal cross-sectional area, resistive index (RI), echogenicity, and glomerular filtration rate (GFR) were performed to evaluate changes during acute rejection. Upon sonographic confirmation of absent diastolic blood flow or a 20% increase in cross-sectional area of the allograft, a nephrectomy and histopathologic evaluation were performed. Acute allograft rejection was confirmed histologically in all cats. Significant increases in renal cross-sectional area (P < 0.001) occurred postoperatively and during rejection. There were no significant changes in RI (P = 0.43) at any time. A subjective increase in medullary echogenicity and a decrease in corticomedullary demarcation were observed in the rejection period. While GFR decreased significantly in the immediate postoperative period (P < 0.001), no further change occurred during rejection (P = 0.42). Changes in RI and GFR do not appear to be sensitive indicators of acute renal allograft rejection in cats. Serial measurements of renal cross-sectional area appear to be a sensitive method for the early diagnosis of allograft rejection in feline renal transplant recipients.     

Bioprospecting from Marine Sediments of New Brunswick,Canada: Exploring the Relationship between Total Bacterial Diversity and Actinobacteria Diversity

Actinomycetes are an important resource for the discovery of natural products with therapeutic properties. Bioprospecting for actinomycetes typically proceeds without a priori knowledge of the bacterial diversity present in sampled habitats. In this study, we endeavored to determine if overall bacterial diversity in marine sediments, as determined by 16S rDNA amplicon pyrosequencing, could be correlated with culturable actinomycete diversity, and thus serve as a powerful tool in guiding future bioprospecting efforts. Overall bacterial diversity was investigated in eight marine sediments from four sites in New Brunswick, Canada, resulting in over 44,000 high quality sequences (x = 5610 per sample). Analysis revealed all sites exhibited significant diversity (H’ = 5.4 to 6.7). Furthermore, statistical analysis of species level bacterial communities (D = 0.03) indicated community composition varied according to site and was strongly influenced by sediment physiochemical composition. In contrast, cultured actinomycetes (n = 466, 98.3% Streptomyces) were ubiquitously distributed among all sites and distribution was not influenced by sediment composition, suggesting that the biogeography of culturable actinomycetes does not correlate with overall bacterial diversity in the samples examined. These actinomycetes provide a resource for future secondary metabolite discovery, as exemplified by the antimicrobial activity observed from preliminary investigation.     

Yield and stability of yield of single- and multi-clover grass-clover swards in two contrasting temperate environments

Diversity of clovers in grass-clover swards may contribute to greater herbage yields and stability of yield. This possible effect was evaluated in an experiment carried out over three harvest years at two contrasting sites, differing in precipitation and soil composition, using mixed swards containing either one, two or three clover species sown together with timothy ( Phleum pratense L.) and meadow fescue ( Festuca pratensis L.). The clover species were red clover ( Trifolium pratense L.), white clover ( Trifolium repens L.) and alsike clover ( Trifolium hybridum L.) sown in various proportions in a total of ten treatments. All swards were fertilized with nitrogen with amounts that increased from year to year, and three harvests were taken in three consecutive years. There was a significant interaction between site and species mixture on total dry matter (DM) yields (range 27–32 tonnes ha⁻¹) and DM yields of clovers (range 5–15 tonnes ha⁻¹); red clover as a single species or in a mixture was superior at the dry site while multi-clover species mixtures were superior at the wet site. Alsike clover was the least productive species of clover. Stability of yield of clovers was generally higher by including white and red clover in the seed mixture but total DM yield was not.