Helicobacter pylori SabA adhesin in persistent infection and chronic inflammation

Helicobacter pylori adherence in the human gastric mucosa involves specific bacterial adhesins and cognate host receptors. Here, we identify sialyl-dimeric-Lewis x glycosphingolipid as a receptor for H. pylori and show that H. pylori infection induced formation of sialyl-Lewis x antigens in gastric epithelium in humans and in a Rhesus monkey. The corresponding sialic acid-binding adhesin (SabA) was isolated with the "retagging" method, and the underlying sabA gene (JHP662/HP0725) was identified. The ability of many H. pylori strains to adhere to sialylated glycoconjugates expressed during chronic inflammation might thus contribute to virulence and the extraordinary chronicity of H. pylori infection.     

Are cadmium, lead and mercury concentrations in mosses across Europe primarily determined by atmospheric deposition of these metals?

Purpose

This study aimed at investigating correlations between heavy metal concentrations in mosses and modelled deposition values as well as other site-specific and regional characteristics to determine which factors primarily affect cadmium, lead and mercury concentrations in mosses. The resulting relationships could potentially be used to enhance the spatial resolution of heavy metal deposition maps across Europe.

Materials and methods

Modelled heavy metal deposition data and data on the concentration of heavy metals in naturally growing mosses were integrated into a geographic information system and analysed by means of bivariate rank correlation analysis and multivariate decision trees. Modelled deposition data were validated annually with deposition measurements at up to 63 EMEP measurement stations within the European Monitoring and Evaluation Programme (EMEP), and mosses were collected at up to 7,000 sites at 5-year intervals between 1990 and 2005.

Results and discussion

Moderate to high correlations were found between cadmium and lead concentrations in mosses and modelled atmospheric deposition of these metals: Spearman rank correlation coefficients were between 0.62 and 0.67, and 0.67 and 0.73 for cadmium and lead, respectively (p?<?0.001). Multivariate decision tree analyses showed that cadmium and lead concentrations in mosses were primarily determined by the atmospheric deposition of these metals, followed by emissions of the metals. Low to very low correlations were observed between mercury concentrations in mosses and modelled atmospheric deposition of mercury. According to the multivariate analyses, spatial variations of the mercury concentration in mosses was primarily associated with the sampled moss species and not with the modelled deposition, but regional differences in the atmospheric chemistry of mercury and corresponding interactions with the moss may also be involved.

Conclusions

At least for cadmium and lead, concentrations in mosses are a valuable tool in determining and mapping the spatial variation in atmospheric deposition across Europe at a high spatial resolution. For mercury, more studies are needed to elucidate interactions of different chemical species with the moss.     

Optimizing the use of open chambers to measure ammonia volatilization in field plots amended with urea

Measuring ammonia(NH₃)volatilization from urea-fertilized soils is crucial for evaluation of practices that reduce gaseous nitrogen(N)losses in agriculture.The small area of chambers used for NH₃volatilization measurements compared with the size of field plots may cause significant errors if inadequate sampling strategies are adopted.Our aims were:i)to investigate the effect of using multiple open chambers on the variability in the measurement of NH₃volatilization in urea-amended field plots and ii)to define the critical period of NH₃-N losses during which the concentration of sampling effort is capable of reducing uncertainty.The use of only one chamber covering 0.015%of the plot(51.84 m²)generates a value of NH₃-N loss within an expected margin of error of 30%around the true mean.To reduce the error margin by half(15%),3–7 chambers were required with a mean of 5 chambers per plot.Concentrating the sampling efforts in the first two weeks after urea application,which is usually the most critical period of N losses and associated errors,represents an efficient strategy to lessen uncertainty in the measurements of NH₃volatilization.This strategy enhances the power of detection of NH₃-N loss abatement in field experiments using chambers.     

Effect of sewage sludge and sugarcane bagasse biochar on soil properties and sugar beet production

Recently, biochar has shown to be an alternative to waste disposal and a source of nutrients, acting as a soil amendment. The effects of two types of biochar on soil properties and sugar beet production as well as potential for carbon (C) sequestration were evaluated:biochar produced from sewage sludge (SB) and biochar produced from a 1:1 mixture of sewage sludge and sugarcane bagasse (MB). A greenhouse pot experiment was conducted using a sandy loam soil from the Brazilian savanna under treatments of MB applications at 2.5%, 5.0%, 7.5%, and 10.0%, SB application at 5.0%, and a conventional fertilization (CF) using lime and mineral fertilizers, with no fertilization as a control. After incubation for 45 d, seedlings were transplanted into each pot and cultivated for 55 d. Biochar characterization showed that pyrolysis reduced the biomass volume drastically, but concentrated the trace elements per unit of biochar weight. The MB treatments increased soil total C (by 27.8%) and pH (by 0.6), reduced the concentrations of nutrients, except for potassium (K), and chromium (Cr), and did not significantly alter lead (Pb) and cadmium (Cd) concentrations. Results of stable isotopes showed that all biochar treatments increased the total soil C stock and stability, suggesting a potential for application in C sequestration, and improved overall soil fertility. However, the biochar treatments also increased the concentrations of trace elements in the soil and plants. The sugar beet yields at 10.0% MB and 5.0% SB corresponded to 55% and 29% of the yield obtained in the CF treatment, respectively. These results may be due to biochar nutrients not being bioavailable when required by plants or to biochar nutrient adsorption.     

Solubilization of iron and calcium phosphates by soil fungi isolated from coffee plantations

Almost 900 fungal isolates were obtained from eight coffee plantations in Colombia and Mexico. Of these, 76 isolates showed activity to solubilize Ca₃(PO₄)₂ (PCa) and FePO₄·H₂O (PFe), which had been added to agar in a plate test. Generally, PCa was better solubilized than PFe. Colombian isolates were generally somewhat less effective than Mexican isolates. The two most effective isolates from each country with apparent highest PFe, solubilization potential were selected and cultivated in liquid medium containing PFe, which is more prevalent in tropical soils. The pH value, solubilized P in the medium and P uptake in fungal biomass were determined. After 24 days, Cylindrocarpon didymum and C. obtusisporum (both from Colombia) had solubilized 9.9 and 6.4 mg PO₄ ^3--P L^?1 and took up 8.6 and 11.6 mg P in biomass. Penicillium janthinellum and Paecilomyces marquandii (both from Mexico) solubilized 7.0 and 1.9 mg PO₄ ^3--P L^?1 and took up 11.3 and 17.3 mg P in biomass. The potential practical use of the four fungal isolates for different strategies in making more P available for coffee growth is discussed.     

Root morphology and acid phosphatase activity in tomato plants during development of and recovery from phosphorus stress

Changes in root morphology and acid phosphatase activity (APA) were followed during the developent of P‐deficiency in tomato plants grown for 7, 14, and 21 days in 0.16 P well aereated nutrient solutions, followed by a period of sufficiency (recovery) in 1 mM P. Plants were harvested weekly for APA, dry weight, and P concentration in roots, stems and leaves, and every 2 weeks for root morphology determinations. APA was highly correlated to development and recovery from P stress. Mixmium values were attained during growth under deficiency and decreased to that of the control plants after a period of recovery in 1 mM P nutrient solutions. Total root weight and average root diameter decreased under P‐stress and root surface area per unit dry weight increased. Efficiency of P utilization (g dry weight/mg absorbed P) was much higher at the end of the stress period but approached that of the controls as P‐supply was restored to sufficiency levels. The implications of these results in developing rapid and reliable screening technigues to detect successful plant performance under P‐stress is discussed.     

First molecular identification of Mycoplasma ovis and 'Candidatus M. haemoovis' from goat, with lack of haemoplasma PCR-positivity in lice

In order to investigate haemotropic Mycoplasma (formerly Eperythrozoon) infection of goats, blood samples and blood-sucking lice (Linognathus stenopsis) were collected in two goat herds. DNA was extracted from 20 blood samples and from 49 lice allocated to six pools according to host individuals. Haemoplasma infection was detected in four goats by real-time PCR. From the sample with the highest bacterial load the simultaneous presence of M. ovis and 'Candidatus M. haemoovis' was demonstrated by cloning and sequencing. Louse pools were haemoplasma negative, including those from bacteraemic animals. However, not only were Anaplasma inclusion bodies seen in blood smears from goats, but relevant PCR-positivity was also detected among lice. This is the first report of a molecular investigation on caprine haemoplasmas, including analysis of their bloodsucking lice. In summary, goats are susceptible to both molecularly characterised ovine haemoplasmas. On the other hand, goat sucking lice (L. stenopsis) do not appear to be potential vectors of these agents.