Theoretical study of structural changes caused by applying mechanical strain on peptide L24

The influence of the mechanical strain on the artificial protein L₂₄ (acetyl-K₂-L₂₄-K₂-amide) has been studied at the molecular mechanics (MM) level of theory. The effect of the surrounding environment (DPPC molecules) has been observed during the stretching or compressing of the L₂₄. The calculations gave the view on the structural changes occurring during these processes. All calculations were done using the GROMACS code with the ffgmx forcefield enhanced with lipid-protein interaction potentials.     

Economic valuation of air pollution mortality: A 9-country contingent valuation survey of value of a life year (VOLY)

This paper provides a key element for the calculation of the damage costs of air pollution, namely the valuation of mortality, important because premature mortality makes by far the largest contribution. Whereas several studies have tried to quantify the cost of air pollution mortality by multiplying a number of deaths by the ‘value of prevented fatality’ (also known as ‘value of statistical life’), we explain why such an approach is not correct and why one needs to evaluate the change in life expectancy due to air pollution. Therefore, an estimate for the monetary value of a life year (VOLY) is needed. The most appropriate method for determining VOLY is contingent valuation (CV). To determine VOLY for the EU, we have conducted a CV survey in 9 European countries: France, Spain, UK, Denmark, Germany, Switzerland, Czech Republic, Hungary, and Poland with a total sample size of 1463 persons. Based on the results from this 9-country CV survey we recommend a VOLY estimate of 40,000 € for cost–benefit analysis of air pollution policies for the European Union. As for confidence intervals, we argue that VOLY is at least 25,000 € and at the most 100,000 €.     

Which agonist properties are important for the activation of 5-HT3A receptors?

Purpose: Why do anesthetics not activate excitatory ligand-gated ion channels such as 5-HT₃ receptors in contrast to inhibitory ligand-gated ion channels? This study examines the actions of structural closely-related 5-HT derivatives and 5-HT constituent parts on 5-HT_3A receptors with the aim of finding simpler if not minimal agonists and thus determining requirements for successful agonist action. Experimental approach: Responses to 5-HT derivatives of human 5-HT_3A receptors stably expressed in HEK 293 cells have been examined with the patch-clamp technique in the outside-out configuration combined with a fast solution exchange system. Results: Phenol, pyrrole and alkyl amines, constituents of 5-HT, even at high concentrations, cannot activate 5-HT_3A receptors but they can inhibit them. To date, tyramines are the smallest known agonists. However, an aromatic ring is not required for activation as acetylcholine is also an agonist of similar strength. Conclusion: Simultaneous interactions of adequate strength at two separate subsites within the 5-HT binding domain appear to be essential for successful agonist function. Anesthetics either fail to achieve this or the activation they produce is so weak that it is masked by a comparatively very strong inhibition.     

Databases as instruments for analysis of large-scale data sets of interactions between molecular biological objects

We have surveyed the most well-known and accessible information resources, consolidating data on interactions of molecular biological objects. Three main criteria are discussed: quality (coverage and reliability) of the information present, ability to analyze experimental data, and ease of results visualization. Several algorithms of data analysis, based on various types of resources, and statistics for its evaluation are named.     

Hormetic doses of UV-C light decrease the susceptibility of tomato plants to Botrytis cinerea infection

Preharvest hormetic doses of UV-C radiation can decrease the susceptibility of tomato leaves to Botrytis cinerea L. infection. UV-C light treatments have been shown to be very effective for reducing disease development in several species, including tomato (Solanum lycopersicum L.). Treating cultivated tomato plants with UV-C light is of interest not only because of the disinfecting effects of UV-C light but also because of its ability to stimulate plant defences (SDP) against diseases, provided that the applied doses are high enough to be effective while low enough to prevent deleterious effects. In the present study, the effects of UV-C light on plants were evaluated by biochemical analyses, including analyses of the activities of antioxidant enzymes and phenylalanine lyase (PAL); the concentration of malondialdehyde (MDA), an indicator of membrane integrity; and chlorophyll fluorescence parameters, such as the maximum quantum efficiency of photosystem II (F_V/F_M) and the Strasser performance index (PI). In this work, treatments with single doses of 0.85 kJ/m² of UV-C light were found to significantly increase plant defences against B. cinerea, reducing the affected leaf area by 51% compared to the affected area of control plants. This decrease in susceptibility was associated with increased PAL activity and the amount of bound phenolics compared to levels in control plants (not treated with UV-C).     

Effect of leaf-to-fruit ratio on leaf nitrogen content and net photosynthesis in girdled branches of Mangifera indica L.

Variations in leaf nitrogen concentration (N_m), mass-to-area ratio (M_a), amount of leaf nitrogen per unit leaf area (N_a), and non-structural carbohydrates were measured in well-lit girdled branches of 11-year-old mango trees that were experiencing similar conditions of irradiance and gap fraction. The influence of source–sink relationships was studied by testing three levels of leaf-to-fruit ratio: 40, 70 and 150, during the period of linear fruit growth. N_a was negatively correlated to the leaf-to-fruit ratio. Differences in N_a were reflected in differences in net photosynthetic assimilation, A_net, although they could not fully account for them. All differences in N_a resulted exclusively from differences in N_m, not M_a. Starch and total non-structural carbohydrates accumulated in the leaves as the result of higher leaf-to-fruit ratio, which suggests that the leaf carbohydrate status may play a role in photosynthetic acclimation to fruit load in mango. These observations complement previous findings where photosynthetic acclimation to light was found to be driven by changes in M_a, while N_m remained almost constant over a large range of gap fractions. Observations about the effect of fruit load were also in contrast with previous observations, since no evidence was found that leaf carbohydrate status played any role in photosynthetic acclimation to light. This study demonstrates that acclimation to changing source–sink relationships does not follow the same pattern as acclimation to progressive shading; but these observations do suggest that there may be different mechanisms by which leaves acclimatise to changing conditions.     

Biological evidence for a precursor protein of serum albumin.

Radioactive leucine was injected into the portal vein of rats followed after 15 seconds by a 180 fold excess of nonradioactive leucine. An albumin-like protein in the liver became highly labelled within 15 minutes after injection. After 150 minutes, the radioactivity in the albumin-like protein had decreased to one tenth. In the serum, radioactively labelled albumin started to appear after 15 minutes and increased there-after up to 150 minutes after injection. Radioactivity in albumin within the liver remained constant at a low level. These results suggest that the albumin-like protein is a biological precursor protein of serum albumin, i.e. a proalbumin.