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Oxidative stress causes dramatic changes in the expression levels of many genes. The formation of a functional protein through successful mRNA translation is central to a coordinated cellular response. To what extent the response towards reactive oxygen species (ROS) is regulated at the translational level is poorly understood. Here we analysed leaf- and tissue-specific translatomes using a set of transgenic Arabidopsis thaliana lines expressing a FLAG-tagged ribosomal protein to immunopurify polysome-bound mRNAs before and after oxidative stress. We determined transcript levels of 171 ROS-responsive genes upon paraquat treatment, which causes formation of superoxide radicals, at the whole-organ level. Furthermore, the translation of mRNAs was determined for five cell types: mesophyll, bundle sheath, phloem companion, epidermal and guard cells. Mesophyll and bundle sheath cells showed the strongest response to paraquat treatment. Interestingly, several ROS-responsive transcription factors displayed cell type-specific translation patterns, while others were translated in all cell types. In part, cell type-specific translation could be explained by the length of the 5-untranslated region (5-UTR) and the presence of upstream open reading frames (uORFs). Our analysis reveals insights into the translational regulation of ROS-responsive genes, which is important to understanding cell-specific responses and functions during oxidative stress.
The study illustrates the response of different Arabidopsis thaliana leaf cells and tissues to oxidative stress at the translational level, an aspect of reactive oxygen species (ROS) biology that has been little studied in the past. Our data reveal insights into how translational regulation of ROS-responsive genes is fine-tuned at the cellular level, a phenomenon contributing to the integrated physiological response of leaves to stresses involving changes in ROS levels.
Assembly and catalysis of molybdenum or tungsten-containing formate dehydrogenases from bacteria
(2015)
The global carbon cycle depends on the biological transformations of C-1 compounds, which include the reductive incorporation of CO2 into organic molecules (e.g. in photosynthesis and other autotrophic pathways), in addition to the production of CO2 from formate, a reaction that is catalyzed by formate dehydrogenases (FDHs). FDHs catalyze, in general, the oxidation of formate to CO2 and H+. However, selected enzymes were identified to act as CO2 reductases, which are able to reduce CO2 to formate under physiological conditions. This reaction is of interest for the generation of formate as a convenient storage form of H-2 for future applications. Cofactor-containing FDHs are found in anaerobic bacteria and archaea, in addition to facultative anaerobic or aerobic bacteria. These enzymes are highly diverse and employ different cofactors such as the molybdenum cofactor (Moco), FeS clusters and flavins, or cytochromes. Some enzymes include tungsten (W) in place of molybdenum (Mo) at the active site. For catalytic activity, a selenocysteine (SeCys) or cysteine (Cys) ligand at the Mo atom in the active site is essential for the reaction. This review will focus on the characterization of Mo- and W-containing FDHs from bacteria, their active site structure, subunit compositions and its proposed catalytic mechanism. We will give an overview on the different mechanisms of substrate conversion available so far, in addition to providing an outlook on bio-applications of FDHs. This article is part of a Special Issue entitled: Cofactor-dependent proteins: evolution, chemical diversity and bio-applications. (C) 2014 Elsevier B.V. All rights reserved.
Challenges in secondary prevention of cardiovascular diseases A review of the current practice
(2015)
With the changing demography of populations and increasing prevalence of co-morbidity, frail patients and more complex cardiac conditions, the modern medicine is facing novel challenges leading to rapid innovation where evidence and experiences are lacking. This scenario is also evident in cardiovascular disease prevention, which continuously needs to accommodate its ever changing strategies, settings, and goals. The present paper summarises actual challenges of secondary prevention, and discusses how this intervention should not only be effective but also efficient. By this way the paper tries to bridge the gaps between research and real-world findings and thereby may find ways to improve standard care. (C) 2014 Elsevier Ireland Ltd. All rights reserved.
Hybrid architectures which combine a MIP with an immobilized affinity ligand or a biocatalyst sum up the advantages of both components. In this paper, hybrid architectures combining a layer of a molecularly imprinted electropolymer with a mini-enzyme or a self-assembled monolayer will be presented. (i) Microperoxidase-11 (MP-11) catalyzed oxidation of the drug aminopyrine on a product-imprinted sublayer: The peroxide dependent conversion of the analyte aminopyrine takes place in the MP-11 containing layer on top of a product-imprinted electropolymer on the indicator electrode. The hierarchical architecture resulted in the elimination of interfering signals for ascorbic acid and uric acid. An advantage of the new hierarchical structure is the separation of MIP formation by electropolymerization and immobilization of the catalyst. In this way it was for the first time possible to integrate an enzyme with a MIP layer in a sensor configuration. This combination has the potential to be transferred to other enzymes, e.g. P450, opening the way to clinically important analytes. (ii) Epitope-imprinted poly-scopoletin layer for binding of the C-terminal peptide and cytochrome c (Cyt c): The MIP binds both the target peptide and the parent protein almost eight times stronger than the non-imprinted polymer with affinities in the lower micromolar range. Exchange of only one amino acid in the peptide decreases the binding by a factor of five. (iii) MUA-poly-scopoletin MIP for cytochrome c: Cyt c bound to the MIP covered gold electrode exhibits direct electron transfer with a redox potential and rate constant typical for the native protein. The MIP cover layer suppresses the displacement of the target protein by BSA or myoglobin. The combination of protein imprinted polymers with an efficient electron transfer is a new concept for characterizing electroactive proteins such as Cyt c. The competition with other proteins shows that the MIP binds its target Cyt c preferentially and that molecular shape and the charge of protein determine the binding of interfering proteins.
Recent analyses have demonstrated that plant metabolic networks do not differ in their structural properties and that genes involved in basic metabolic processes show smaller coexpression than genes involved in specialized metabolism. By contrast, our analysis reveals differences in the structure of plant metabolic networks and patterns of coexpression for genes in (non)specialized metabolism. Here we caution that conclusions concerning the organization of plant metabolism based on network-driven analyses strongly depend on the computational approaches used.
Background Balance training (BT) has been used for the promotion of balance and sports-related skills as well as for prevention and rehabilitation of lower extremity sport injuries. However, evidence-based dose-response relationships in BT parameters have not yet been established.
Objective The objective of this systematic literature review and meta-analysis was to determine dose-response relationships in BT parameters that lead to improvements in balance in young healthy adults with different training status.
Data Sources A computerized systematic literature search was performed in the electronic databases PubMed, Web of Knowledge, and SPORTDiscus from January 1984 up to May 2014 to capture all articles related to BT in young healthy adults.
Study Eligibility Criteria A systematic approach was used to evaluate the 596 articles identified for initial review. Only randomized controlled studies were included if they investigated BT in young healthy adults (16-40 years) and tested at least one behavioral balance performance outcome. In total, 25 studies met the inclusion criteria for review.
Study Appraisal and Synthesis Methods Studies were evaluated using the physiotherapy evidence database (PEDro) scale. Within-subject effect sizes (ESdw) and between-subject effect sizes (ESdb) were calculated. The included studies were coded for the following criteria: training status (elite athletes, sub-elite athletes, recreational athletes, untrained subjects), training modalities (training period, frequency, volume, etc.), and balance outcome (test for the assessment of steady-state, proactive, and reactive balance).
Results Mean ESdb demonstrated that BT is an effective means to improve steady-state (ESdb = 0.73) and proactive balance (ESdb = 0.92) in healthy young adults. Studies including elite athletes showed the largest effects (ESdb = 1.29) on measures of steady-state balance as compared with studies analyzing sub-elite athletes (ESdb = 0.32), recreational athletes (ESdb = 0.69), and untrained subjects (ESdb = 0.82). Our analyses regarding dose-response relationships in BT revealed that a training period of 11-12 weeks (ESdb = 1.09), a training frequency of three (mean ESdb = 0.72) or six (single ESdb = 1.84) sessions per week, at least 16-19 training sessions in total (ESdb = 1.12), a duration of 11-15 min for a single training session (ESdb = 1.11), four exercises per training session (ESdb = 1.29), two sets per exercise (ESdb = 1.63), and a duration of 21-40 s for a single BT exercise (ESdb = 1.06) is most effective in improving measures of steady-state balance. Due to a small number of studies, dose-response relationships of BT for measures of proactive and reactive balance could not be qualified.
Limitations The present findings must be interpreted with caution because it is difficult to separate the impact of a single training modality (e.g., training frequency) from that of the others. Moreover, the quality of the included studies was rather limited, with a mean PEDro score of 5.
Conclusions Our detailed analyses revealed effective BT parameters for the improvement of steady-state balance. Thus, practitioners and coaches are advised to consult the identified dose-response relationships of this systematic literature review and meta-analysis to implement effective BT protocols in clinical and sports-related contexts. However, further research of high methodological quality is needed to (1) determine dose-response relationships of BT for measures of proactive and reactive balance, (2) define effective sequencing protocols in BT (e.g., BT before or after a regular training session), (3) discern the effects of detraining, and (4) develop a feasible and effective method to regulate training intensity in BT.