Traveling for nature? On the paradox of environmental awareness and travel for nature experiences

Climate change is widely regarded as the major environmental problem facing the world today. Due to this, transportation, including traveling for recreational purposes, is now being thoroughly examined. Still, and despite a growing awareness of the impact of traveling, the demand for nature based tourism holds its position in general and, paradoxically, also among environmentalists. To understand this paradox, a qualitative study was conducted of Nature and Youth Sweden, to explore an organization that combines a profound commitment to the environment with a great outdoor interest. Data were gathered through focus groups with district boards and by a content analysis of the organization\u27s magazine. Results show that recreational traveling of environmentalists may be explained by the practice of placing nature in remote and "pristine" areas. Preferences for places characterized by biodiversity, natural quiet, an absence of other people as well as human impact reflect a desire among environmentalists to distance themselves from contemporary urban society. This desire outweighs one of their most important environmental concerns: global warming. Even though the members of Nature and Youth Sweden reject traveling by air on environmental grounds, it is concluded that environmentalism appears to be a reason for traveling, rather than a barrier

A 2-pyridone-amide inhibitor targets the glucose metabolism pathway of Chlamydia trachomatis.

UnlabelledIn a screen for compounds that inhibit infectivity of the obligate intracellular pathogen Chlamydia trachomatis, we identified the 2-pyridone amide KSK120. A fluorescent KSK120 analogue was synthesized and observed to be associated with the C. trachomatis surface, suggesting that its target is bacterial. We isolated KSK120-resistant strains and determined that several resistance mutations are in genes that affect the uptake and use of glucose-6-phosphate (G-6P). Consistent with an effect on G-6P metabolism, treatment with KSK120 blocked glycogen accumulation. Interestingly, KSK120 did not affect Escherichia coli or the host cell. Thus, 2-pyridone amides may represent a class of drugs that can specifically inhibit C. trachomatis infection.ImportanceChlamydia trachomatis is a bacterial pathogen of humans that causes a common sexually transmitted disease as well as eye infections. It grows only inside cells of its host organism, within a parasitophorous vacuole termed the inclusion. Little is known, however, about what bacterial components and processes are important for C. trachomatis cellular infectivity. Here, by using a visual screen for compounds that affect bacterial distribution within the chlamydial inclusion, we identified the inhibitor KSK120. As hypothesized, the altered bacterial distribution induced by KSK120 correlated with a block in C. trachomatis infectivity. Our data suggest that the compound targets the glucose-6-phosphate (G-6P) metabolism pathway of C. trachomatis, supporting previous indications that G-6P metabolism is critical for C. trachomatis infectivity. Thus, KSK120 may be a useful tool to study chlamydial glucose metabolism and has the potential to be used in the treatment of C. trachomatis infections

Истмико-цервикальная недостаточность и беременность: диагностика, лечение, профилактика

МЕТОДИЧЕСКИЕ РЕКОМЕНДАЦИИШЕЙКИ МАТКИ ФУНКЦИОНАЛЬНАЯ НЕДОСТАТОЧНОСТЬБЕРЕМЕННОСТИ ОСЛОЖНЕНИЯАБОРТ ПРИВЫЧНЫЙСЕРКЛЯЖ ШЕЙКИ МАТКИПРОГЕСТЕРОНПЕССАРИИИНТЕРНЫКЛИНИЧЕСКИЕ ОРДИНАТОРЫВ рекомендациях описаны современные методы диагностики и лечения пациентов с истмико-цервикальной недостаточностью, тактика ведения беременности при несостоятельности шейки матки. Издание предназначено для врачей акушеров-гинекологов, студентов медицинских вузов, врачей-интернов, клинических ординаторов

Linkage between fitness of yeast cells and adenylate kinase catalysis

Enzymes have evolved with highly specific values of their catalytic parameters kcat and KM. This poses fundamental biological questions about the selection pressures responsible for evolutionary tuning of these parameters. Here we are address these questions for the enzyme adenylate kinase (Adk) in eukaryotic yeast cells. A plasmid shuffling system was developed to allow quantification of relative fitness (calculated from growth rates) of yeast in response to perturbations of Adk activity introduced through mutations. Biophysical characterization verified that all variants studied were properly folded and that the mutations did not cause any substantial differences to thermal stability. We found that cytosolic Adk is essential for yeast viability in our strain background and that viability could not be restored with a catalytically dead, although properly folded Adk variant. There exist a massive overcapacity of Adk catalytic activity and only 12% of the wild type kcat is required for optimal growth at the stress condition 20°C. In summary, the approach developed here has provided new insights into the evolutionary tuning of kcat for Adk in a eukaryotic organism. The developed methodology may also become useful for uncovering new aspects of active site dynamics and also in enzyme design since a large library of enzyme variants can be screened rapidly by identifying viable colonies

Conformational Exchange Processes in Biological Systems: Detection by Solid-State NMR

International audienceWe review recent advances in methodologies to study microseconds-to-milliseconds exchange processes in biological molecules using magic-angle spinning solid-state nuclear magnetic resonance (MAS ssNMR) spectroscopy. The particularities of MAS ssNMR, as compared to solution-state NMR, are elucidated using numerical simulations and experimental data. These simulations reveal the potential of MAS NMR to provide detailed insight into short-lived conformations of biological molecules. Recent studies of conformational exchange dynamics in microcrystalline ubiquitin are discussed

On the conservation of the slow conformational dynamics within the amino acid kinase family: NAGK the paradigm

N-Acetyl-L-Glutamate Kinase (NAGK) is the structural paradigm for examining the catalytic mechanisms and dynamics of amino acid kinase family members. Given that the slow conformational dynamics of the NAGK (at the microseconds time scale or slower) may be rate-limiting, it is of importance to assess the mechanisms of the most cooperative modes of motion intrinsically accessible to this enzyme. Here, we present the results from normal mode analysis using an elastic network model representation, which shows that the conformational mechanisms for substrate binding by NAGK strongly correlate with the intrinsic dynamics of the enzyme in the unbound form. We further analyzed the potential mechanisms of allosteric signalling within NAGK using a Markov model for network communication. Comparative analysis of the dynamics of family members strongly suggests that the low-frequency modes of motion and the associated intramolecular couplings that establish signal transduction are highly conserved among family members, in support of the paradigm sequence→structure→dynamics→function © 2010 Marcos et al

Dynamics on multiple timescales in the RNA-directed RNA polymerase from the cystovirus ϕ6

The de novo initiating RNA-directed RNA polymerase (RdRP), P2, forms the central machinery in the infection cycle of the bacteriophage ϕ6 by performing the dual tasks of replication and transcription of the double-stranded RNA genome in the host cell. By measurement and quantitative analysis of multiple-quantum spin-relaxation data for the δ1 positions of Ile residues that are distributed over the 3D-fold of P2, we find that the enzyme is dynamic both on the fast (ps–ns) and slow (µs–ms) timescales. The characteristics of several motional modes including those that coincide with the catalytic timescale (500–800/s) are altered in the presence of substrate analogs and single-stranded RNA templates. These studies reveal the plasticity of this finely tuned molecular machine and represent a first step towards linking structural information available from a host of crystal structures to catalytic mechanisms and timescales obtained from the measurements of kinetics for homologous systems in solution

PCDB: a database of protein conformational diversity

PCDB (http://www.pcdb.unq.edu.ar) is a database of protein conformational diversity. For each protein, the database contains the redundant compilation of all the corresponding crystallographic structures obtained under different conditions. These structures could be considered as different instances of protein dynamism. As a measure of the conformational diversity we use the maximum RMSD obtained comparing the structures deposited for each domain. The redundant structures were extracted following CATH structural classification and cross linked with additional information. In this way it is possible to relate a given amount of conformational diversity with different levels of information, such as protein function, presence of ligands and mutations, structural classification, active site information and organism taxonomy among others. Currently the database contains 7989 domains with a total of 36581 structures from 4171 different proteins. The maximum RMSD registered is 26.7 Å and the average of different structures per domain is 4.5