Detection of rhodococcus equi by microbiological culture and by polymerase chain reaction in samples of tracheobronchial secretions of foals

The goal of the present study was to investigate whether new PCR-methods would improve diagnostic of R. equi. In a first step, sensitivity and specificity of the PCR-methods in respect to the"gold standard" microbiological culture were determined. Secondly, sensitivity and specificity of both microbiological methods were evaluated in respect to the clinical diagnosis. The tracheobronchial secretions of 48 foals with pulmonary abscesses and of 37 healthy foals were evaluated by bacteriological culture as well as by four PCR-methods: aceA-, ideR-, vapA- and VP-PCR. In respect to the"gold standard" microbiological culture, the sensitivity of most PCR methods lay between 63.9 and 69.4 % except the vapA-PCR (27.8 %).The specificity of all PCR methods in this comparison was between 98 to 100 %. In this analysis, clinical diagnosis had a low sensitivity (66.7 %) and a low specificity (51.0 %). In respect to the clinical diagnosis, microbiological culture sensitivity was 50.0 % and specificity 67.7 9%. In this analysis, sensitivity rates of aceA-, ideR and VP-PCR methods lay between 33.3 and 37.5 %, sensitivity of the vapA-PCR was lower (10.4 %).The specificity of all PCR methods ranged from 78.4 to 86.5 %. In conclusion, these results show that the diagnostic potential of the microbiological methods"Culture" and "PCR" is different and that for the diagnosis of R. equi-pneumonia in foals the combination of microbiological culture with PCR should be used for examination of samples of the airways of foals.     

The use of photometric test kits for investigations of soil enzyme activities

The objective was to test the applicability of different photometric test kits for the determination of potential and actual nitrification and the activities of urease, invertase, and cellobiase in soil. Three water affected grassland sites, influenced by the maritime climate were investigated. The results obtained by the test kits and by standard methods were similar. Soil organic matter content was found as most important factor determining the enzyme activities on these three grassland sites with similar pH‐values. At the site with the largest soil organic matter content the highest activities for urease, invertase, and cellobiase were found. However, this was not true for the nitrification rates.     

Distribution of Al and Heavy Metals in Bulk Soil and Aggregates at Three Sites Contaminated by the Emissions of a Central Slovak Al Smelter

Large spoils of metal-rich filtercake from the Port Kembla BHP steelworks were characterised by certain physical, chemical and biological parameters. The vegetation was assessed for potential metal hyperaccumulators and the presence of arbuscular mycorrhizae in the rhizospheres. Fresh filtercake (<2 yr old) was charcoal in colour and had a fine (clay loam) texture. Its composition was distinctly different to the older filtercake (3–4 yr) which was similar to the reference soil, being lighter in colour, loamy textured, more aggregated and with higher organic matter. Variability between the two filtercake types also occurred for electrical conductivity and pH. Total trace metal concentrations (Cd, Cu, Pb and Zn) were high and although only minor proportions were in bioavailable forms, the greater percentages in the older filtercake suggested temporal changes in metal speciation. Fresh filtercake was devoid of any plant life and fungal communities. The older material, however, was able to sustain a reasonable environment for plant, bacterial and fungal growth. The vegetation was dominated by Ricinus communis, along with species belonging to the families Asteraceae, Solanaceae, Malvaceae and Apiaceae. Rhizosphere of all these plants harboured mycorrhizae belonging to the Gigaspora and Glomus strains and while trace metal accumulation was observed no plant was a hyperaccumulator. The reference site was principally inhabited by certain Poaceae, Asteraceae and Verbenaceae species. All were mycorrhizal (principally Glomus strains), but no plant was represented on the contaminated site. Here also trace metal accumulation was taking place. The absence of hyperaccumulation in the filtercake was considered a consequence of low levels of bioavailable trace metals. However, as such metal forms may increase over time, particularly for copper and lead, cultivation of known hyperaccumulators could become worthwhile after prolonged exposure (>4 yr). Among the naturally colonising plants, Ricinus communis and Sonchus oleraceus are regarded the most suitable options for zinc and cadmium removal, respectively. Arbuscular mycorrhizal infection (particularly with Glomus and Gigaspora strains) should be promoted for optimum soil reclamation.     

The protective role of ascorbic acid (vitamin C) against chlorpyrifos-induced oxidative stress in Oreochromis niloticus

Ability of ascorbic acid (vitamin C) to attenuate oxidative damage was evaluated in liver and brain tissues of Oreochromis niloticus (O. niloticus) experimentally exposed to sublethal concentrations of chlorpyrifos (CPF). O. niloticus was exposed to sublethal concentrations of CPF at 12?μg/L (CPF1) and 24?μg/L (CPF2) for 96?h. The fish of vitamin C (Vit C) and CPF2?+?Vit C groups were fed with Vit C supplemented diet (200?mg Vit C/100?g feed). A significant increase in thiobarbituric acid-reactive substances (TBARS) level (P?相似文献   

Molecular architecture and assembly principles of Vibrio cholerae biofilms

In their natural environment, microbes organize into communities held together by an extracellular matrix composed of polysaccharides and proteins. We developed an in vivo labeling strategy to allow the extracellular matrix of developing biofilms to be visualized with conventional and superresolution light microscopy. Vibrio cholerae biofilms displayed three distinct levels of spatial organization: cells, clusters of cells, and collections of clusters. Multiresolution imaging of living V. cholerae biofilms revealed the complementary architectural roles of the four essential matrix constituents: RbmA provided cell-cell adhesion; Bap1 allowed the developing biofilm to adhere to surfaces; and heterogeneous mixtures of Vibrio polysaccharide, RbmC, and Bap1 formed dynamic, flexible, and ordered envelopes that encased the cell clusters.     

Chemical and biological characterization of cinnamic acid derivatives from cell cultures of lavender (Lavandula officinalis) induced by stress and jasmonic acid

Cell cultures of lavender (Lavandula officinalis) were analyzed for the metabolite profile under normal growth conditions and under stress as well as after jasmonic acid treatment. The main compound synthesized was rosmarinic acid, which was also secreted into the culture medium. Different solvent extraction methods at different pH values altered the profile slightly. Anoxic stress induced the synthesis of a cinnamic acid derivative, which was identified as caffeic acid by gas chromatography-mass spectrometry. Caffeic acid was also induced after treatment of the cell cultures with jasmonic acid. Although the antioxidative activity of both compounds, rosmarinic acid and caffeic acid, was confirmed in an assay using 2,2-diphenyl-1-picrylhydrazyl (DPPH), it was demonstrated that both substances have a low cytotoxic potential in vitro using acute myeloid leukemia (HL-60) cells. The potential of the system for finding new bioactive compounds is discussed.     

Vasoconstriction: a new activity for platelet-derived growth factor

Platelet-derived growth factor (PDGF) is a potent mitogen for vascular smooth muscle cells that has been implicated in the pathogenesis of atherosclerosis. The potential role of PDGF in the altered vasoreactivity of atherosclerotic vessels has been studied through an examination of its effects on contractility in the rat aorta. PDGF caused a concentration-dependent contraction of aortic strips and was significantly more potent on a molar basis than the classic vasoconstrictor peptide angiotensin II. Furthermore, PDGF increased the cytosolic free calcium concentration in cultured rat aortic smooth muscle cells. These observations suggest a new biological activity for PDGF that may contribute to the enhanced vasoreactivity of certain atherosclerotic vessels.     

Spirocyclic Drimanes from the Marine Fungus Stachybotrys sp. Strain MF347

A novel spirocyclic drimane coupled by two drimane fragment building blocks 2 and a new drimane 1 were identified in mycelia and culture broth of Stachybotrys sp. MF347. Their structures were established by spectroscopic means. This is the first example of spirocyclic drimane coupled by a spirodihydrobenzofuranlactam unit and a spirodihydroisobenzofuran unit; and the connecting position being N-C instead of an N and N connecting unit. Strain MF347 produced also the known spirocyclic drimanes stachybocin A (12) and stachybocin B (11) featured by two sesquiterpene-spirobenzofuran structural units connected by a lysine residue; the known spirocyclic drimanes chartarlactam O (5); chartarlactam K (6); F1839A (7); stachybotrylactam (8); stachybotramide (9); and 2α-acetoxystachybotrylactam acetate (10); as well as ilicicolin B (13), a known sesquiterpene. The relative configuration of two known spirobenzofuranlactams (3 and 4) was determined. All compounds were subjected to biological activity tests. The spirocyclic drimane 2, 11, and 12, as well as the sesquiterpene 13, exhibited antibacterial activity against the clinically relevant methicillin-resistant Staphylococcus aureus (MRSA).