Species-specific antigens ofMycoplasma hyopneumoniae and cross-reactions with other porcine mycoplasmas

Cell proteins from the porcine mycoplasmasMycoplasma hyorhinis, M. hyopneumoniae, andM. flocculare have been analyzed by SDS-gel electrophoresis and immunoblotting. The protein profiles ofM. hyopneumoniae andM. flocculare were similar, but the protein profile ofM. hyorhinis was quite different from the others. Antisera prepared against whole cells of the above three mycoplasmas were used in immunoblotting of electrophoretically separated antigens and in enzyme-linked immunosorbent assay. One major antigen, which had a molecular weight of 73 k, was found to be common to all three mycoplasmas. Another major antigen, with a molecular weight of 41 k, was common toM. hyopneumoniae andM. flocculare and may also be present inM. hyorhinis. Several antigens of comparatively high molecular weights (108 k, 102 k, 93 k, 89 k, and 87 k) seemed to be specific forM. hyopneumoniae. Three antisera prepared by immunization of rabbits with immunoprecipitates obtained by crossed immunoelectrophoresis ofM. hyopneumoniae were also used in blotting experiments. One of these antisera was found to be directed against the 73 k antigen common to the three porcine mycoplasmas investigated. The other two antisera were directed againstM. hyopneumoniae-specific antigens with molecular weights of 74 k, 58 k, 45 k, 44 k, and 38 k.     

Inefficacy of oxygenated drinking water in accelerating ethanol elimination in humans

In our earlier report it was found that after intravenous infusion of ethanol into monkeys the drinking of oxygenated water accelerated their elimination rate of ethanol 60% on the average. The acceleration was assumed to be due to increased hepatic oxygen tension through the portal blood flow. Now we have repeated similar experiments using humans as subjects. In humans the elimination rate of ethanol was not changed by oxygenated drinks. We are not able to explain the species difference, because the mechanism by which oxygenated water increased ethanol elimination in monkeys is unsettled.     

The Effect of Nitrogen and Glyphosate on Survival and Colonisation of Perennial Grass Species in an Agro-Ecosystem: Does the Relative Importance of Survival Decrease with Competitive Ability?

The ecological success of a plant species is typically described by the observed change in plant abundance or cover, but in order to more fully understand the fundamental plant ecological processes, it is necessary to inspect the underlying processes of survival and colonization and how they are affected by environmental conditions. A general ecological hypothesis on the effect of environmental gradients on demographic parameters is proposed and tested. The hypothesis is that decreasing fitness or competitive ability along an environmental gradient is associated with an increasing importance of survival for regulating the abundance of the species. The tested hypothesis is related to both the stress gradient hypothesis and whether the importance of competition increases along productivity gradients. The combined effect of nitrogen and glyphosate on the survival and colonization probability of two perennial grass species, Festuca ovina and Agrostis capillaris, which are known to differ in their responses to both glyphosate and nitrogen treatments, is calculated using pin-point cover data in permanent frames. We found that the relative importance of survival increased with the level of glyphosate for the glyphosate sensitive A. capillaris and decreased for the glyphosate tolerant F. ovina. Likewise, increasing levels of nitrogen increased the importance of survival for the relative nitrophobic F. ovina. Consequently, the proposed hypothesis was corroborated in this specific study. The proposed method will enable predictions of the effects of agricultural practices on community dynamics in a relatively simple setup eliminating the need to quantify all the interaction among the species in the plant community. The method will be immediately useful for the regulation of non-cultivated buffer strips between agricultural fields and semi-natural and natural biotopes such as hedgerows and waterways.     

How reliable are molecular dynamics simulations of membrane active antimicrobial peptides?

Membrane-active antimicrobial peptides (AMPs) are challenging to study experimentally, but relatively easy to investigate using molecular dynamics (MD) computer simulations. For this reason, a large number of MD studies of AMPs have been reported over recent years. Yet relatively little effort has focused on the validity of such simulations. Are these results reliable, and do they agree with what is known experimentally? And how much meaningful information can be obtained? To answer these questions, we demonstrate here some of the requirements and limitations of running MD simulations for several common AMPs: PGLa, melittin, maculatin and BP100. The two most important findings are: (a) simulation results depend strongly on force field parameters, making experimental verification of the simulations obligatory, and (b) slow orientational and conformational fluctuations mean that much longer sampling timescales (multi-μs) are needed if quantitative agreement between simulation averages and experimental data is to be achieved. This article is part of a Special Issue entitled: Interfacially Active Peptides and Proteins. Guest Editors: William C. Wimley and Kalina Hristova.     

Hcp2, a Secreted Protein of the Phytopathogen Pseudomonas syringae pv. Tomato DC3000, Is Required for Fitness for Competition against Bacteria and Yeasts

When analyzing the secretome of the plant pathogen Pseudomonas syringae pv. tomato DC3000, we identified hemolysin-coregulated protein (Hcp) as one of the secreted proteins. Hcp is assumed to be an extracellular component of the type VI secretion system (T6SS). Two copies of hcp genes are present in the P. syringae pv. tomato DC3000 genome, hcp1 (PSPTO_2539) and hcp2 (PSPTO_5435). We studied the expression patterns of the hcp genes and tested the fitness of hcp knockout mutants in host plant colonization and in intermicrobial competition. We found that the hcp2 gene is expressed most actively at the stationary growth phase and that the Hcp2 protein is secreted via the T6SS and appears in the culture medium as covalently linked dimers. Expression of hcp2 is not induced in planta and does not contribute to virulence in or colonization of tomato or Arabidopsis plants. Instead, hcp2 is required for survival in competition with enterobacteria and yeasts, and its function is associated with the suppression of the growth of these competitors. This is the first report on bacterial T6SS-associated genes functioning in competition with yeast. Our results suggest that the T6SS of P. syringae may play an important role in bacterial fitness, allowing this plant pathogen to survive under conditions where it has to compete with other microorganisms for resources.     

How hazardous is the Sahara Desert crossing for migratory birds? Indications from satellite tracking of raptors

We investigated the risk associated with crossing the Sahara Desert for migrating birds by evaluating more than 90 journeys across this desert by four species of raptors (osprey Pandion haliaetus, honey buzzard Pernis apivorus, marsh harrier Circus aeruginosus and Eurasian hobby Falco subbuteo) recorded by satellite telemetry. Forty per cent of the crossings included events of aberrant behaviours, such as abrupt course changes, slow travel speeds, interruptions, aborted crossings followed by retreats from the desert and failed crossings due to death, indicating difficulties for the migrants. The mortality during the Sahara crossing was 31 per cent per crossing attempt for juveniles (first autumn migration), compared with only 2 per cent for adults (autumn and spring combined). Mortality associated with the Sahara passage made up a substantial fraction (up to about half for juveniles) of the total annual mortality, demonstrating that this passage has a profound influence on survival and fitness of migrants. Aberrant behaviours resulted in late arrival at the breeding grounds and an increased probability of breeding failure (carry-over effects). This study also demonstrates that satellite tracking can be a powerful method to reveal when and where birds are exposed to enhanced risk and mortality during their annual cycles.     

Exercise rehabilitation on home-dwelling patients with Alzheimer's disease - a randomized, controlled trial. Study protocol

Background

The Turkish population living in the Netherlands has a high prevalence of psychological complaints and has a high threshold for seeking professional help for these problems. Seeking help through the Internet can overcome these barriers. This project aims to evaluate the effectiveness of a guided self-help problem-solving intervention for depressed Turkish migrants that is culturally adapted and web-based.

Methods

This study is a randomized controlled trial with two arms: an experimental condition group and a wait list control group. The experimental condition obtains direct access to the guided web-based self-help intervention, which is based on Problem Solving Treatment (PST) and takes 6 weeks to complete. Turkish adults with mild to moderate depressive symptoms will be recruited from the general population and the participants can choose between a Turkish and a Dutch version. The primary outcome measure is the reduction of depressive symptoms, the secondary outcome measures are somatic symptoms, anxiety, acculturation, quality of life and satisfaction. Participants are assessed at baseline, post-test (6 weeks), and 4 months after baseline. Analysis will be conducted on the intention-to-treat sample.

Discussion

This study evaluates the effectiveness of a guided problem-solving intervention for Turkish adults living in the Netherlands that is culturally adapted and web-based.

Trial Registration

Nederlands Trial Register: NTR2303     

Economic consequences of mastitis and withdrawal of milk with high somatic cell count in Swedish dairy herds

The main aim was to assess the impact of mastitis on technical and economic results of a dairy herd under current Swedish farming conditions. The second aim was to investigate the effects obtained by withdrawing milk with high somatic cell count (SCC). A dynamic and stochastic simulation model, SimHerd, was used to study the effects of mastitis in a herd with 150 cows. Results given the initial incidence of mastitis (32 and 33 clinical and subclinical cases per 100 cow-years, respectively) were studied, together with the consequences of reducing or increasing the incidence of mastitis by 50%, modelling no clinical mastitis (CM) while keeping the incidence of subclinical mastitis (SCM) constant and vice versa. Six different strategies to withdraw milk with high SCC were compared. The decision to withdraw milk was based on herd-level information in three scenarios: withdrawal was initiated when the predicted bulk tank SCC exceeded 220 000, 200 000 or 180 000 cells/ml, and on cow-level information in three scenarios: withdrawal was initiated when the predicted SCC in an individual cow's milk exceeded 1 000 000, 750 000 or 500 000 cells/ml. The accuracy with which SCC was measured and predicted was assumed to affect the profitability of withdrawing milk with high SCC and this was investigated by applying high, low or no uncertainty to true SCC. The yearly avoidable cost of mastitis was estimated at €8235, assuming that the initial incidence of mastitis could be reduced by 50%. This cost corresponded to 5% of the herd net return given the initial incidence of mastitis. Expressed per cow-year, the avoidable cost of mastitis was €55. The costs per case of CM and SCM were estimated at €278 and €60, respectively. Withdrawing milk with high SCC was never profitable because this generated a substantial amount of milk withdrawal that was not offset by a sufficient increase in the average price per delivered kg milk. It had the most negative impact on net return when high incidence of mastitis was simulated. Withdrawing milk with high SCC based on low-uncertainty information reduced the amount of withdrawn milk and thus resulted in less negative effect on net return. It was concluded that the current milk-pricing system makes it more profitable for farmers to sell a larger amount of milk with higher SCC than to withdraw milk with high SCC to obtain payment premiums, at least in herds with mastitis incidences within the simulated ranges.