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An efficient electrocatalytic biosensor for sulfite detection was developed by co-immobilizing sulfite oxidase and cytochrome c with polyaniline sulfonic acid in a layer-by-layer assembly. QCM, UV-Vis spectroscopy and cyclic voltammetry revealed increasing loading of electrochemically active protein with the formation of multilayers. The sensor operates reagentless at low working potential. A catalytic oxidation current was detected in the presence of sulfite at the modified gold electrode, polarized at +0.1 V ( vs. Ag/AgCl 1 M KCl). The stability of the biosensor performance was characterized and optimized. A 17-bilayer electrode has a linear range between 1 and 60 mu M sulfite with a sensitivity of 2.19 mA M-1 sulfite and a response time of 2 min. The electrode retained a stable response for 3 days with a serial reproducibility of 3.8% and lost 20% of sensitivity after 5 days of operation. It is possible to store the sensor in a dry state for more than 2 months. The multilayer electrode was used for determination of sulfite in unspiked and spiked samples of red and white wine. The recovery and the specificity of the signals were evaluated for each sample.
We present varve chronologies for sediments from two maar lakes in the Valle de Santiago region (Central Mexico): Hoya La Alberca (AD 1852-1973) and Hoya Rincn de Parangueo (AD 1839-1943). These are the first varve chronologies for Mexican lakes. The varved sections were anchored with tephras from Colima (1913) and Paricutin (1943/1944) and (210)Pb ages. We compare the sequences using the thickness of seasonal laminae and element counts (Al, Si, S, Cl, K, Ti, Mn, Fe, and Sr) determined by micro X-ray fluorescence spectrometry. The formation of the varve sublaminae is attributed to the strongly seasonal climate regime. Limited rainfall and high evaporation rates in winter and spring induce precipitation of carbonates (high Ca, Sr) enriched in (13)C and (18)O, whereas rainfall in summer increases organic and clastic input (plagioclase, quartz) with high counts of lithogenic elements (K, Al, Ti, and Si). Eolian input of Ti occurs also in the dry season. Moving correlations (5-yr windows) of the Ca and Ti counts show similar development in both sequences until the 1930s. Positive correlations indicate mixing of allochthonous Ti and autochthonous Ca, while negative correlations indicate their separation in sublaminae. Negative excursions in the correlations correspond with historic and reconstructed droughts, El Nio events, and positive SST anomalies. Based on our data, droughts (3-7 year duration) were severe and centred around the following years: the early 1850s, 1865, 1880, 1895, 1905, 1915 and the late 1920s with continuation into the 1930s. The latter dry period brought both lake systems into a critical state making them susceptible to further drying. Groundwater overexploitation due to the expansion of irrigation agriculture in the region after 1940 induced the transition from calcite to aragonite precipitation in Alberca and halite infiltration in Rincn. The proxy data indicate a faster response to increased evaporation for Rincn, the lake with the larger maar dimensions, solar radiation receipt and higher conductivity, whereas the smaller, steeper Alberca maar responded rapidly to increased precipitation.
rezensierte Werke: Bachmann, Cordula: Kleidung und Geschlecht : Ethnographische Erkundungen einer Alltagspraxis / Cordula Bachmann. - Bielefeld : transcript Verlag, 2008. - 154 S. ISBN 978-3-89942-920-6 Pape, Cora von: Kunstkleider : die Präsenz des Körpers in textilen Kunst-Objekten des 20. Jahrhunderts / Cora von Pape. - Bielefeld : transcript Verlag, 2008. - 225 S. ISBN 978-3-89942-825-4 Zwei neue Studien widmen sich dem Verhältnis von Kleidung und Geschlecht beziehungsweise Kleidung und Körper. Wie Frauen und Männer in ihrer alltäglichen Praxis des ‚Sich-Kleidens‘ mit den modischen Erscheinungsbildern von Männlichkeit oder Weiblichkeit umgehen, untersucht die Kulturwissenschaftlerin Cordula Bachmann. Sie wertet aktuelle Interviews zum Kleidungsverhalten von Frauen und Männern aus und rückt dabei die Perspektive der Handelnden, die das alltägliche ‚Sich-Kleiden‘ als eine primäre soziale Anforderung zu lösen haben, ins Zentrum des Interesses. Den aufsehenerregenden künstlerischen Umgang mit Kleidung in Form von textilen Kunstobjekten, die sich mit dem menschlichen Körper befassen und der Art und Weise, wie er mittels Kleidung und Textilien repräsentiert oder transformiert wird, untersucht die Kunsthistorikerin Cora von Pape. Das alltägliche weibliche Chaos des Sich-Ankleidens angesichts der täglichen Herausforderung, sich bei der Entscheidung für oder gegen ein Kleid, sich auch für oder gegen eine Frauenrolle entscheiden zu müssen, das in den von Bachmann ausgewerteten Interviews thematisiert wird, scheint auch in den Performances oder textilen Kunstobjekten vieler von Cordula von Pape vorgestellten Künstlerinnen der 2. Hälfte des 20. Jahrhunderts auf, allerdings künstlerisch-experimentell bearbeitet in eindrucksvollen (Selbst-)Inszenierungen, die der gewaltigen Symbolik des Sich-Ankleidens, der Kleider als Körperhüllen oder Reliquien, die an die Stelle des verschwundenen Körpers treten, auf den Grund gehen.
Am 8. August 2008 richtete sich alle mediale Aufmerksamkeit schlagartig von Beijing und den Olympischen Spielen auf den Kaukasus – genauer: auf Georgien. Unvorbereitet traf die Meldung über den Krieg im Kaukasus aber nur diejenigen, die glaubten, die „eingefrorenen Konflikte“ im Süden des Gebirgszuges seien beigelegt. Seit den Kriegen um die „abtrünnigen Teilrepubliken“ Georgiens, Südossetien und Abchasien, in den frühen 1990er Jahren sind diese jedoch nie zur Ruhe gekommen.
A macro-tidal freshwater ecosystem recovering from hypereutrophication : the Schelde lease study
(2009)
We report a 40 year record of eutrophication and hypoxia on an estuarine ecosystem and its recovery from hypereutrophication. After decades of high inorganic nutrient concentrations and recurring anoxia and hypoxia, we observe a paradoxical increase in chlorophyll-a concentrations with decreasing nutrient inputs. We hypothesise that algal growth was inhibited due to hypereutrophication, either by elevated ammonium concentrations, severe hypoxia or the production of harmful substances in such a reduced environment. We study the dynamics of a simple but realistic mathematical model, incorporating the assumption of algal growth inhibition. It shows a high algal biomass, net oxygen production equilibrium with low ammonia inputs, and a low algal biomass, net oxygen consumption equilibrium with high ammonia inputs. At intermediate ammonia inputs it displays two alternative stable states. Although not intentional, the numerical output of this model corresponds to observations, giving extra support for assumption of algal growth inhibition. Due to potential algal growth inhibition, the recovery of hypereutrophied systems towards a classical eutrophied state, will need reduction of waste loads below certain thresholds and will be accompanied by large fluctuations in oxygen concentrations. We conclude that also flow-through systems, heavily influenced by external forcings which partly mask internal system dynamics, can display multiple stable states.
The study of non-coding RNA genes has received increased attention in recent years fuelled by accumulating evidence that larger portions of genomes than previously acknowledged are transcribed into RNA molecules of mostly unknown function, as well as the discovery of novel non-coding RNA types and functional RNA elements. Here, we demonstrate that specific properties of graphs that represent the predicted RNA secondary structure reflect functional information. We introduce a computational algorithm and an associated web-based tool (GraPPLE) for classifying non-coding RNA molecules as functional and, furthermore, into Rfam families based on their graph properties. Unlike sequence-similarity-based methods and covariance models, GraPPLE is demonstrated to be more robust with regard to increasing sequence divergence, and when combined with existing methods, leads to a significant improvement of prediction accuracy. Furthermore, graph properties identified as most informative are shown to provide an understanding as to what particular structural features render RNA molecules functional. Thus, GraPPLE may offer a valuable computational filtering tool to identify potentially interesting RNA molecules among large candidate datasets.
Rain fall-runoff response in temperate humid headwater catchments is mainly controlled by hydrolo gical processes at the hillslope scale. Applied tracer experiments with fluore scent dye and salt tracers are well known tools in groundwater studies at the large scale and vadose zone studies at the plot scale, where they provide a means to characterise subsurface flow. We extend this approach to the hillslope scale to investigate saturated and unsaturated flow path s concertedly at a forested hill slope in the Austrian Alps. Dye staining experiments at the plot scale revealed that crack s and soil pipe s function as preferential flow path s in the fine-textured soils of the study area, and these preferenti al flow structures were active in fast subsurface transport of tracers at the hillslope scale. Breakthrough curves obtained under steady flow conditions could be fitted well to a one-dimensional convection-dispersion model. Under natural rain fall a positive correlation of tracer concentrations to the transient flows was observed. The results of this study demon strate qualitative and quantitative effects of preferential flow feature s on subsurface stormflow in a temperate humid headwater catchment. It turn s out that , at the hill slope scale, the interaction s of structures and processes are intrinsically complex, which implies that attempts to model such a hillslope satisfactorily require detailed investigation s of effective structures and parameters at the scale of interest.
Background: Biological systems adapt to changing environments by reorganizing their cellula r and physiological program with metabolites representing one important response level. Different stresses lead to both conserved and specific responses on the metabolite level which should be reflected in the underl ying metabolic network. Methodology/Principal Findings: Starting from experimental data obtained by a GC-MS based high-throughput metabolic profiling technology we here develop an approach that: (1) extracts network representations from metabolic conditiondependent data by using pairwise correlations, (2) determines the sets of stable and condition-dependent correlations based on a combination of statistical significance and homogeneity tests, and (3) can identify metabolites related to the stress response, which goes beyond simple ob servation s about the changes of metabolic concentrations. The approach was tested with Escherichia colias a model organism observed under four different environmental stress conditions (cold stress, heat stress, oxidative stress, lactose diau xie) and control unperturbed conditions. By constructing the stable network component, which displays a scale free topology and small-world characteristics, we demonstrated that: (1) metabolite hubs in this reconstructed correlation networks are significantly enriched for those contained in biochemical networks such as EcoCyc, (2) particular components of the stable network are enriched for functionally related biochemical path ways, and (3) ind ependently of the response scale, based on their importance in the reorganization of the cor relation network a set of metabolites can be identified which represent hypothetical candidates for adjusting to a stress-specific response. Conclusions/Significance: Network-based tools allowed the identification of stress-dependent and general metabolic correlation networks. This correlation-network-ba sed approach does not rely on major changes in concentration to identify metabolites important for st ress adaptation, but rather on the changes in network properties with respect to metabolites. This should represent a useful complementary technique in addition to more classical approaches.
Many cellular processes require decision making mechanisms, which must act reliably even in the unavoidable presence of substantial amounts of noise. However, the multistable genetic switches that underlie most decision-making processes are dominated by fluctuations that can induce random jumps between alternative cellular states. Here we show, via theoretical modeling of a population of noise-driven bistable genetic switches, that reliable timing of decision-making processes can be accomplished for large enough population sizes, as long as cells are globally coupled by chemical means. In the light of these results, we conjecture that cell proliferation, in the presence of cell-cell communication, could provide a mechanism for reliable decision making in the presence of noise, by triggering cellular transitions only when the whole cell population reaches a certain size. In other words , the summation performed by the cell population would average out the noise and reduce its detrimental impact.
Myrmecochory, i.e. dispersal of seeds by ants towards and around their nests, plays an important role in temperate forests. Yet hardly any study has examined plant population spread over several years and the underlying joint contribution of a hierarchy of dispersal modes and plant demography. We used a seed-sowing approach with three replicates to examine colonization patterns of Melampyrum pratense, an annual myrmecochorous herb, in a mixed Scots pine forest in northeastern Germany. Using a spatially explicit individualbased (SEIB) model population patterns over 4 years were explained by short-distance transport of seeds by small ant species with high nest densities, resulting in random spread. However, plant distributions in the field after another 4 years were clearly deviating from model predictions. Mean annual spread rate increased from 0.9 m to 5.1 m per year, with a clear inhomogeneous component. Obviously, after a lag-phase of several years, non-random seed dispersal by large red wood ants (Formica rufa) was determining the species’ spread, thus resulting in stratified dispersal due to interactions with different-sized ant species. Hypotheses on stratified dispersal, on dispersal lag, and on non-random dispersal were verified using an extended SEIB model, by comparison of model outputs with field patterns (individual numbers, population areas, and maximum distances). Dispersal towards red wood ant nests together with seed loss during transport and redistribution around nests were essential features of the model extension. The observed lag-phase in the initiation of non-random, medium-distance transport was probably due to a change of ant behaviour towards a new food source of increasing importance, being a meaningful example for a lag-phase in local plant species invasion. The results demonstrate that field studies should check model predictions wherever possible. Future research will show whether or not the M. pratense–ant system is representative for migration patterns of similar animal dispersal systems after having crossed range edges by long-distance dispersal events.
Background: The EXO (EXORDIUM) gene was identified as a potential mediator of brassinosteroid (BR)-promoted growth. It is part of a gene family with eight members in Arabidopsis. EXO gene expression is under control of BR, and EXO overexpression promotes shoot and root growth. In this study, the consequences of loss of EXO function are described. Results: The exo loss of function mutant showed diminished leaf and root growth and reduced biomass production. Light and scanning electron microscopy analyses revealed that impaired leaf growth is due to reduced cell expansion. Epidermis, palisade, and spongy parenchyma cells were smaller in comparison to the wild-type. The exo mutant showed reduced brassinolide-induced cotyledon and hypocotyl growth. In contrast, exo roots were significantly more sensitive to the inhibitory effect of synthetic brassinolide. Apart from reduced growth, exo did not show severe morphological abnormalities. Gene expression analyses of leaf material identified genes that showed robust EXO-dependent expression. Growth-related genes such as WAK1, EXP5, and KCS1, and genes involved in primary and secondary metabolism showed weaker expression in exo than in wild-type plants. However, the vast majority of BR-regulated genes were normally expressed in exo. HA- and GFP-tagged EXO proteins were targeted to the apoplast. Conclusion: The EXO gene is essential for cell expansion in leaves. Gene expression patterns and growth assays suggest that EXO mediates BR-induced leaf growth. However, EXO does not control BR-levels or BR-sensitivity in the shoot. EXO presumably is involved in a signalling process which coordinates BR-responses with environmental or developmental signals. The hypersensitivity of exo roots to BR suggests that EXO plays a diverse role in the control of BR responses in the root.
The temporal dynamics of hydrological model performance gives insights into errors that cannot be obtained from global performance measures assigning a single number to the fit of a simulated time series to an observed reference series. These errors can include errors in data, model parameters, or model structure. Dealing with a set of performance measures evaluated at a high temporal resolution implies analyzing and interpreting a high dimensional data set. This paper presents a method for such a hydrological model performance assessment with a high temporal resolution and illustrates its application for two very different rainfall-runoff modeling case studies. The first is the Wilde Weisseritz case study, a headwater catchment in the eastern Ore Mountains, simulated with the conceptual model WaSiM-ETH. The second is the Malalcahuello case study, a headwater catchment in the Chilean Andes, simulated with the physicsbased model Catflow. The proposed time-resolved performance assessment starts with the computation of a large set of classically used performance measures for a moving window. The key of the developed approach is a data-reduction method based on self-organizing maps (SOMs) and cluster analysis to classify the high-dimensional performance matrix. Synthetic peak errors are used to interpret the resulting error classes. The final outcome of the proposed method is a time series of the occurrence of dominant error types. For the two case studies analyzed here, 6 such error types have been identified. They show clear temporal patterns, which can lead to the identification of model structural errors.
Background: Phosphorylation of proteins plays a crucial role in the regulation and activation of metabolic and signaling pathways and constitutes an important target for pharmaceutical intervention. Central to the phosphorylation process is the recognition of specific target sites by protein kinases followed by the covalent attachment of phosphate groups to the amino acids serine, threonine, or tyrosine. The experimental identification as well as computational prediction of phosphorylation sites (P-sites) has proved to be a challenging problem. Computational methods have focused primarily on extracting predictive features from the local, one-dimensional sequence information surrounding phosphorylation sites. Results: We characterized the spatial context of phosphorylation sites and assessed its usability for improved phosphorylation site predictions. We identified 750 non-redundant, experimentally verified sites with three-dimensional (3D) structural information available in the protein data bank (PDB) and grouped them according to their respective kinase family. We studied the spatial distribution of amino acids around phosphorserines, phosphothreonines, and phosphotyrosines to extract signature 3D-profiles. Characteristic spatial distributions of amino acid residue types around phosphorylation sites were indeed discernable, especially when kinase-family-specific target sites were analyzed. To test the added value of using spatial information for the computational prediction of phosphorylation sites, Support Vector Machines were applied using both sequence as well as structural information. When compared to sequence-only based prediction methods, a small but consistent performance improvement was obtained when the prediction was informed by 3D-context information. Conclusion: While local one-dimensional amino acid sequence information was observed to harbor most of the discriminatory power, spatial context information was identified as relevant for the recognition of kinases and their cognate target sites and can be used for an improved prediction of phosphorylation sites. A web-based service (Phos3D) implementing the developed structurebased P-site prediction method has been made available at http://phos3d.mpimp-golm.mpg.de.
Background: Mitochondrial genomes are a valuable source of data for analysing phylogenetic relationships. Besides sequence information, mitochondrial gene order may add phylogenetically useful information, too. Sipuncula are unsegmented marine worms, traditionally placed in their own phylum. Recent molecular and morphological findings suggest a close affinity to the segmented Annelida. Results: The first complete mitochondrial genome of a member of Sipuncula, Sipunculus nudus, is presented. All 37 genes characteristic for metazoan mtDNA were detected and are encoded on the same strand. The mitochondrial gene order (protein-coding and ribosomal RNA genes) resembles that of annelids, but shows several derivations so far found only in Sipuncula. Sequence based phylogenetic analysis of mitochondrial protein-coding genes results in significant bootstrap support for Annelida sensu lato, combining Annelida together with Sipuncula, Echiura, Pogonophora and Myzostomida. Conclusion: The mitochondrial sequence data support a close relationship of Annelida and Sipuncula. Also the most parsimonious explanation of changes in gene order favours a derivation from the annelid gene order. These results complement findings from recent phylogenetic analyses of nuclear encoded genes as well as a report of a segmental neural patterning in Sipuncula.
Spatial patterns as well as temporal dynamics of soil moisture have a major influence on runoff generation. The investigation of these dynamics and patterns can thus yield valuable information on hydrological processes, especially in data scarce or previously ungauged catchments. The combination of spatially scarce but temporally high resolution soil moisture profiles with episodic and thus temporally scarce moisture profiles at additional locations provides information on spatial as well as temporal patterns of soil moisture at the hillslope transect scale. This approach is better suited to difficult terrain (dense forest, steep slopes) than geophysical techniques and at the same time less cost-intensive than a high resolution grid of continuously measuring sensors. Rainfall simulation experiments with dye tracers while continuously monitoring soil moisture response allows for visualization of flow processes in the unsaturated zone at these locations. Data was analyzed at different spacio-temporal scales using various graphical methods, such as space-time colour maps (for the event and plot scale) and binary indicator maps (for the long-term and hillslope scale). Annual dynamics of soil moisture and decimeterscale variability were also investigated. The proposed approach proved to be successful in the investigation of flow processes in the unsaturated zone and showed the importance of preferential flow in the Malalcahuello Catchment, a datascarce catchment in the Andes of Southern Chile. Fast response times of stream flow indicate that preferential flow observed at the plot scale might also be of importance at the hillslope or catchment scale. Flow patterns were highly variable in space but persistent in time. The most likely explanation for preferential flow in this catchment is a combination of hydrophobicity, small scale heterogeneity in rainfall due to redistribution in the canopy and strong gradients in unsaturated conductivities leading to self-reinforcing flow paths.
For three small, mountainous catchments in Germany two medium-range forecast systems are compared that predict precipitation for up to 5 days in advance. One system is composed of the global German weather service (DWD) model, GME, which is dynamically downscaled using the COSMO-EU regional model. The other system is an empirical (expanded) downscaling of the ECMWF model IFS. Forecasts are verified against multi-year daily observations, by applying standard skill scores to events of specified intensity. All event classes are skillfully predicted by the empirical system for up to five days lead time. For the available prediction range of one to two days it is superior to the dynamical system.
ChlamyCyc : an integrative systems biology database and web-portal for Chlamydomonas reinhardtii
(2009)
Background: The unicellular green alga Chlamydomonas reinhardtii is an important eukaryotic model organism for the study of photosynthesis and plant growth. In the era of modern highthroughput technologies there is an imperative need to integrate large-scale data sets from highthroughput experimental techniques using computational methods and database resources to provide comprehensive information about the molecular and cellular organization of a single organism. Results: In the framework of the German Systems Biology initiative GoFORSYS, a pathway database and web-portal for Chlamydomonas (ChlamyCyc) was established, which currently features about 250 metabolic pathways with associated genes, enzymes, and compound information. ChlamyCyc was assembled using an integrative approach combining the recently published genome sequence, bioinformatics methods, and experimental data from metabolomics and proteomics experiments. We analyzed and integrated a combination of primary and secondary database resources, such as existing genome annotations from JGI, EST collections, orthology information, and MapMan classification. Conclusion: ChlamyCyc provides a curated and integrated systems biology repository that will enable and assist in systematic studies of fundamental cellular processes in Chlamydomonas. The ChlamyCyc database and web-portal is freely available under http://chlamycyc.mpimp-golm.mpg.de.
Human information processing depends critically on continuous predictions about upcoming events, but the temporal convergence of expectancy-based top-down and input-driven bottom-up streams is poorly understood. We show that, during reading, event-related potentials differ between exposure to highly predictable and unpredictable words no later than 90 ms after visual input. This result suggests an extremely rapid comparison of expected and incoming visual information and gives an upper temporal bound for theories of top-down and bottom-up interactions in object recognition.
Background: The loss of photosynthesis has occurred often in eukaryotic evolution, even more than its acquisition, which occurred at least nine times independently and which generated the evolution of the supergroups Archaeplastida, Rhizaria, Chromalveolata and Excavata. This secondary loss of autotrophic capability is essential to explain the evolution of eukaryotes and the high diversity of protists, which has been severely underestimated until recently. However, the ecological and evolutionary scenarios behind this evolutionary ‘‘step back’’ are still largely unknown. Methodology/Principal Findings: Using a dynamic model of heterotrophic and mixotrophic flagellates and two types of prey, large bacteria and ultramicrobacteria, we examine the influence of DOC concentration, mixotroph’s photosynthetic growth rate, and external limitations of photosynthesis on the coexistence of both types of flagellates. Our key premises are: large bacteria grow faster than small ones at high DOC concentrations, and vice versa; and heterotrophic flagellates are more efficient than the mixotrophs grazing small bacteria (both empirically supported). We show that differential efficiency in bacteria grazing, which strongly depends on cell size, is a key factor to explain the loss of photosynthesis in mixotrophs (which combine photosynthesis and bacterivory) leading to purely heterotrophic lineages. Further, we show in what conditions an heterotroph mutant can coexist, or even out-compete, its mixotrophic ancestor, suggesting that bacterivory and cell size reduction may have been major triggers for the diversification of eukaryotes. Conclusions/Significance: Our results suggest that, provided the mixotroph’s photosynthetic advantage is not too large, the (small) heterotroph will also dominate in nutrient-poor environments and will readily invade a community of mixotrophs and bacteria, due to its higher efficiency exploiting the ultramicrobacteria. As carbon-limited conditions were presumably widespread throughout Earth history, such a scenario may explain the numerous transitions from phototrophy to mixotrophy and further to heterotrophy within virtually all major algal lineages. We challenge prevailing concepts that affiliated the evolution of phagotrophy with eutrophic or strongly light-limited environments only.
We propose two strategies to characterize organisms with respect to their metabolic capabilities. The first, investigative, strategy describes metabolic networks in terms of their capability to utilize different carbon sources, resulting in the concept of carbon utilization spectra. In the second, predictive, approach minimal nutrient combinations are predicted from the structure of the metabolic networks, resulting in a characteristic nutrient profile. Both strategies allow for a quantification of functional properties of metabolic networks, allowing to identify groups of organisms with similar functions. We investigate whether the functional description reflects the typical environments of the corresponding organisms by dividing all species into disjoint groups based on whether they are aerotolerant and/or photosynthetic. Despite differences in the underlying concepts, both measures display some common features. Closely related organisms often display a similar functional behavior and in both cases the functional measures appear to correlate with the considered classes of environments. Carbon utilization spectra and nutrient profiles are complementary approaches toward a functional classification of organism-wide metabolic networks. Both approaches contain different information and thus yield different clusterings, which are both different from the classical taxonomy of organisms. Our results indicate that a sophisticated combination of our approaches will allow for a quantitative description reflecting the lifestyles of organisms.
The ability of an organism to survive depends on its capability to adapt to external conditions. In addition to metabolic versatility and efficient replication, reliable signal transduction is essential. As signaling systems are under permanent evolutionary pressure one may assume that their structure reflects certain functional properties. However, despite promising theoretical studies in recent years, the selective forces which shape signaling network topologies in general remain unclear. Here, we propose prevention of autoactivation as one possible evolutionary design principle. A generic framework for continuous kinetic models is used to derive topological implications of demanding a dynamically stable ground state in signaling systems. To this end graph theoretical methods are applied. The index of the underlying digraph is shown to be a key topological property which determines the so-called kinetic ground state (or off-state) robustness. The kinetic robustness depends solely on the composition of the subdigraph with the strongly connected components, which comprise all positive feedbacks in the network. The component with the highest index in the feedback family is shown to dominate the kinetic robustness of the whole network, whereas relative size and girth of these motifs are emphasized as important determinants of the component index. Moreover, depending on topological features, the maintenance of robustness differs when networks are faced with structural perturbations. This structural off-state robustness, defined as the average kinetic robustness of a network’s neighborhood, turns out to be useful since some structural features are neutral towards kinetic robustness, but show up to be supporting against structural perturbations. Among these are a low connectivity, a high divergence and a low path sum. All results are tested against real signaling networks obtained from databases. The analysis suggests that ground state robustness may serve as a rationale for some structural peculiarities found in intracellular signaling networks.
With the increasing availability of observational data from different sources at a global level, joint analysis of these data is becoming especially attractive. For such an analysis – oftentimes with little prior knowledge about local and global interactions between the different observational variables at hand – an exploratory, data-driven analysis of the data may be of particular relevance. In the present work we used generalized additive models (GAM) in an exemplary study of spatio-temporal patterns in the tropospheric NO2-distribution derived from GOME satellite observations (1996 to 2001) at global scale. We focused on identifying correlations between NO2 and local wind fields, a quantity which is of particular interest in the analysis of spatio-temporal interactions. Formulating general functional, parametric relationships between the observed NO2 distribution and local wind fields, however, is difficult – if not impossible. So, rather than following a modelbased analysis testing the data for predefined hypotheses (assuming, for example, sinusoidal seasonal trends), we used a GAM with non-parametric model terms to learn this functional relationship between NO2 and wind directly from the data. The NO2 observations showed to be affected by winddominated processes over large areas. We estimated the extent of areas affected by specific NO2 emission sources, and were able to highlight likely atmospheric transport “pathways”. General temporal trends which were also part of our model – weekly, seasonal and linear changes – showed to be in good agreement with previous studies and alternative ways of analysing the time series. Overall, using a non-parametric model provided favorable means for a rapid inspection of this large spatio-temporal NO2 data set, with less bias than parametric approaches, and allowing to visualize dynamical processes of the NO2 distribution at a global scale.
Synonymous codon usage and variations in the level of isoaccepting tRNAs exert a powerful selective force on translation fidelity. We have developed an algorithm to evaluate the relative rate of translation which allows large-scale comparisons of the non-uniform translation rate on the protein biogenesis. Using the complete genomes of Escherichia coli and Bacillus subtilis we show that stretches of codons pairing to minor tRNAs form putative sites to locally attenuate translation; thereby the tendency is to cluster in near proximity whereas long contiguous stretches of slow-translating triplets are avoided. The presence of slow-translating segments positively correlates with the protein length irrespective of the protein abundance. The slow-translating clusters are predominantly located down-stream of the domain boundaries presumably to fine-tune translational accuracy with the folding fidelity of multidomain proteins. Translation attenuation patterns at highly structurally and functionally conserved domains are preserved across the species suggesting a concerted selective pressure on the codon selection and species-specific tRNA abundance in these regions.
Background: In Arabidopsis thaliana, the family of cyclic nucleotide-gated channels (CNGCs) is composed of 20 members. Previous studies indicate that plant CNGCs are involved in the control of growth processes and responses to abiotic and biotic stresses. According to their proposed function as cation entry pathways these channels contribute to cellular cation homeostasis, including calcium and sodium, as well as to stress-related signal transduction. Here, we studied the expression patterns and regulation of CNGC19 and CNGC20, which constitute one of the five CNGC subfamilies. Results: GUS, GFP and luciferase reporter assays were used to study the expression of CNGC19 and CNGC20 genes from Arabidopsis thaliana in response to developmental cues and salt stress. CNGC19 and CNGC20 were differentially expressed in roots and shoots. The CNGC19 gene was predominantly active in roots already at early growth stages. Major expression was observed in the phloem. CNGC20 showed highest promoter activity in mesophyll cells surrounding the veins. Its expression increased during development and was maximal in mature and senescent leaves. Both genes were upregulated in the shoot in response to elevated NaCl but not mannitol concentrations. While in the root, CNGC19 did not respond to changes in the salt concentration, in the shoot it was strongly upregulated in the observed time frame (6-72 hours). Salt-induction of CNGC20 was also observed in the shoot, starting already one hour after stress treatment. It occurred with similar kinetics, irrespective of whether NaCl was applied to roots of intact plants or to the petiole of detached leaves. No differences in K and Na contents of the shoots were measured in homozygous T-DNA insertion lines for CNGC19 and CNGC20, respectively, which developed a growth phenotype in the presence of up to 75 mM NaCl similar to that of the wild type. Conclusion: Together, the results strongly suggest that both channels are involved in the salinity response of different cell types in the shoot. Upon salinity both genes are upregulated within hours. CNGC19 and CNGC20 could assist the plant to cope with toxic effects caused by salt stress, probably by contributing to a re-allocation of sodium within the plant.
Background: Research concerning child's food intake have considered various influencing factors, for example parental feeding strategies, demographic and weight factors. At this time, however, there are few findings that explore these factors simultaneously. Accordingly, the aim of this study was to test a structural equation model regarding the associations between maternal feeding strategies and child's food intake. Methods: 556 mothers and their children between 1 and 10 years of age participated in this crosssectional study. Besides socio-demographic and weight data, the mothers were asked about their feeding strategies as well as their child's food intake. Results: The well-fitting model explained 73% of the variance in the child's consumption of healthy and 34% of unhealthy food. In addition to the effect of the mother's social status and the child's age, a rewarding and modeling feeding behavior significantly influenced the child's food intake. Conclusion: The results highlight the relevance of maternal feeding behavior on the child's food intake. In terms of preventing eating- or weight-related problems, the findings indicate the usefulness of training parents in explicit modeling behavior and avoiding food as a reward.
Site directed mutagenesis of amino acid residues at the active site of mouse aldehyde oxidase AOX1
(2009)
Mouse aldehyde oxidase (mAOX1) forms a homodimer and belongs to the xanthine oxidase family of molybdoenzymes which are characterized by an essential equatorial sulfur ligand coordinated to the molybdenum atom. In general, mammalian AOs are characterized by broad substrate specificity and an yet obscure physiological function. To define the physiological substrates and the enzymatic characteristics of mAOX1, we established a system for the heterologous expression of the enzyme in Eschericia coli. The recombinant protein showed spectral features and a range of substrate specificity similar to the native protein purified from mouse liver. The EPR data of recombinant mAOX1 were similar to those of AO from rabbit liver, but differed from the homologous xanthine oxidoreductase enzymes. Site-directed mutagenesis of amino acids Val806, Met884 and Glu1265 at the active site resulted in a drastic decrease in the oxidation of aldehydes with no increase in the oxidation of purine substrates. The double mutant V806E/M884R and the single mutant E1265Q were catalytically inactive enzymes regardless of the aldehyde or purine substrates tested. Our results show that only Glu1265 is essential for the catalytic activity by initiating the base-catalyzed mechanism of substrate oxidation. In addition, it is concluded that the substrate specificity of molybdo-flavoenzymes is more complex and not only defined by the three characterized amino acids in the active site.
Special p-forms are forms which have components fµ1…µp equal to +1, -1 or 0 in some orthonormal basis. A p-form ϕ ∈ pRd is called democratic if the set of nonzero components {ϕμ1...μp} is symmetric under the transitive action of a subgroup of O(d,Z) on the indices {1, . . . , d}. Knowledge of these symmetry groups allows us to define mappings of special democratic p-forms in d dimensions to special democratic P-forms in D dimensions for successively higher P = p and D = d. In particular, we display a remarkable nested structure of special forms including a U(3)-invariant 2-form in six dimensions, a G2-invariant 3-form in seven dimensions, a Spin(7)-invariant 4-form in eight dimensions and a special democratic 6-form O in ten dimensions. The latter has the remarkable property that its contraction with one of five distinct bivectors, yields, in the orthogonal eight dimensions, the Spin(7)-invariant 4-form. We discuss various properties of this ten dimensional form.
Background: Very recently a gene marker panel that allows the mutational analysis of APC, CTNNB1, B-RAF and K-RAS was conceived. The aim of the present study was to use the 4-gene marker panel covering the Wnt and Ras-Raf-MEK-MAPK signalling pathways to determine the percentage of sporadic colorectal carcinomas (CRC) carrying at least one of the four above-mentioned genes in a mutated form alone and/or in combination with microsatellite instability (MSI) and to compare the sensitivity of the gene marker panel used in this study with that of gene marker panels previously reported in the scientific literature. Methods: CTNNB1 and B-RAF were screened by PCR-single-strand conformation polymorphism analysis and K-RAS gene mutations by restriction fragment length polymorphism analysis. For the mutational analysis of the APC gene mutation cluster region (codons 1243–1567) direct DNA sequencing was performed. The U.S. National Cancer Institute microsatellite panel (BAT25, BAT26, D2S123, D5S346 and D17S250) was used for MSI analysis. Results: It could be shown that about 80% of early stage CRC (UICC stages I and II) and over 90% of CRC in the UICC stage IV carried at least one mutated gene and/or showed MSI. No significant increase in the gene mutation frequencies could be determined when comparing tumours in the UICC stage I with those in UICC stage IV. Conclusions: When compared with previously published gene marker panels the 4-gene marker panel used in the present study shows an excellent performance, allowing to detect genetic alterations in 80–90% of human sporadic CRC samples analyzed.
We examined individual differences in masked repetition priming by re-analyzing item-level response-time (RT) data from three experiments. Using a linear mixed model (LMM) with subjects and items specified as crossed random factors, the originally reported priming and word-frequency effects were recovered. In the same LMM, we estimated parameters describing the distributions of these effects across subjects. Subjects’ frequency and priming effects correlated positively with each other and negatively with mean RT. These correlation estimates, however, emerged only with a reciprocal transformation of RT (i.e., -1/RT), justified on the basis of distributional analyses. Different correlations, some with opposite sign, were obtained (1) for untransformed or logarithmic RTs or (2) when correlations were computed using within-subject analyses. We discuss the relevance of the new results for accounts of masked priming, implications of applying RT transformations, and the use of LMMs as a tool for the joint analysis of experimental effects and associated individual differences.
Microsaccades are very small, involuntary flicks in eye position that occur on average once or twice per second during attempted visual fixation. Microsaccades give rise to EMG eye muscle spikes that can distort the spectrum of the scalp EEG and mimic increases in gamma band power. Here we demonstrate that microsaccades are also accompanied by genuine and sizeable cortical activity, manifested in the EEG. In three experiments, high-resolution eye movements were corecorded with the EEG: during sustained fixation of checkerboard and face stimuli and in a standard visual oddball task that required the counting of target stimuli. Results show that microsaccades as small as 0.15° generate a field potential over occipital cortex and midcentral scalp sites 100 –140 ms after movement onset, which resembles the visual lambda response evoked by larger voluntary saccades. This challenges the standard assumption of human brain imaging studies that saccade-related brain activity is precluded by fixation, even when fully complied with. Instead, additional cortical potentials from microsaccades were present in 86% of the oddball task trials and of similar amplitude as the visual response to stimulus onset. Furthermore, microsaccade probability varied systematically according to the proportion of target stimuli in the oddball task, causing modulations of late stimulus-locked event-related potential (ERP) components. Microsaccades present an unrecognized source of visual brain signal that is of interest for vision research and may have influenced the data of many ERP and neuroimaging studies.
Mit diesem Appell unterstützen die ehemaligen Präsidenten Polens Lech Wałęsa und Aleksander Kwaśniewski sowie der ehemalige polnische Ministerpräsident Tadeusz Mazowiecki den Abrüstungsappell des neuen US-Präsidenten Barack Obama. Dieser hat das Ziel einer atomwaffenfreien Welt wieder auf die internationale Agenda gehoben. Angesichts ihrer historischen Erfahrungen befürworten die Polen diese Anti-Atomwaffen-Initiative. Um dieser mehr Rückenwind zu verleihen, könnte auch ein stärkeres Engagement führender deutscher Politiker nicht schaden.
Rezensionen
(2009)
"Vor der deutschen Außen- und Sicherheitspolitik steht eine Fülle schwieriger und unaufschiebbarer Weichenstellungen für die nächsten Jahre. Gegenwärtig mangelt es ihr an notwendiger Konsistenz und Zielsicherheit, um den richtigen und angemessenen Zugang zu den sich immer schneller verändernden Konstellationen der Weltpolitik, ihren neuen Machtverhältnissen, Strategien und Bewegungsrichtungen zu finden. Die nachfolgenden Rezensionen vermitteln zwar Hinweise auf ihre Gestaltung, können gleichwohl größtenteils nur den Stand der Dinge von 2008 erfassen."
Außenpolitik in Schwarz-Rot
(2009)
Die Jahre der Großen Koalition neigen sich dem Ende zu. Bilanz wird gezogen, auch in der Außenpolitik. Ob Europäische Union oder die Beziehungen zu den USA, zu Polen, Russland oder China, ob im Krieg in Afghanistan oder beim Kampf gegen somalische Piraten – oft glich die deutsche Außenpolitik einem Drahtseilakt in den Turbulenzen dieser Welt. Im vorliegenden WeltTrends-Heft diskutieren Politiker und Wissenschaftler die Höhen und Tiefen, die Leistungen und die Defizite der Schwarz-Roten-Außenpolitik der letzten vier Jahre.
Welchen Aufgaben soll sich die NATO zuwenden? Wo soll sie enden? Als klassisches Militärbündnis verliert sie jedenfalls an Bedeutung. Die gegenwärtige Krise der regionalen Allianz mit globaler Reichweite muss genutzt werden für eine strategische Neuausrichtung der Struktur und Funktion des Bündnisses. Die Rolle der NATO als Werkzeug für multinationale Interventionen entscheidet über die Bildung globaler Koalitionen.
Wort und Strich
(2009)
Die NATO gilt als das erfolgreichste Militärbündnis der Geschichte. Dabei war sie immer zugleich auch ein politisches Bündnis. Notwendig ist die aktuelle Selbstvergewisserung zu Zweck und Hauptaufgaben. Verteidigung, Stabilisierung Europas und internationale Friedensmissionen werden dazu gehören. Wichtig bleibt ein gemeinsamer Wille zum praktischen Untersetzen durch verbesserte militärische Fähigkeiten. Die Allianz sollte das spezifische militärische Instrument in die breiteren internationalen sicherheitsrelevanten Bemühungen einbringen.
Jemen – Ein verlorenes Land?
(2009)
Im Jemen schwelt es. Gerade in diesen Tagen werden wir mit Schrecken an die prekäre Lage des Landes erinnert. Die Wiedervereinigung des Jemen 1990 war ein wichtiger Schritt hin zur Stabilisierung. Dennoch existieren viele Probleme, deren Lösung für die Entwicklung des Landes und seine Sicherheit relevant sind. Die Autorin, seit 2007 selbst in Sanaa tätig, zeigt die Probleme des Landes und ihre vielschichtigen Ursachen auf.
Die „Gasabhängigkeit“ Europas von Russland ist ein Scheinproblem. Es gibt gegenseitige Abhängigkeiten, die auch Russlands Handeln begrenzen. Für den Russlandexperten Roland Götz wird das politisch motivierte Vorantreiben einer von Russland unabhängigen Energieversorgung nicht nur erfolglos bleiben, sondern auch den Aufbau eines partnerschaftlichen Verhältnisses zwischen Europa und Russland erschweren.
Dass die Große Koalition die Kontinuität deutscher Außenpolitik fortsetzt, ist für den Autor, verteidigunspolitischer Sprecher von DIE LINKE, ein Zeichen der Stagnation, sogar des Versagens. Er wirft der Bundesregierung Einfallslosigkeit, mangelndes Engagement und kalte Interessenpolitik vor. Doch neben der umfassenden Kritik werden auch neue Lösungsansätze vorgestellt, die sich auf Erwartungen an die neue US-Administration stützen.
Europäische Union als globale Macht : Plädoyer für eine wertbestimmte interregionale Ordnungsmacht
(2009)
Viele betrachten die EU als einen behäbigen Koloss, den widerstreitende Interessen lähmen. Der Autor weist die Kritiker jedoch in ihre Schranken. In seinem flammenden Plädoyer für die EU veranschaulicht er ihre positive Wirkung nach außen. Dabei kommt er zu dem Schluss, dass die Aufgaben Europas als universale Wertegemeinschaft im Bereich des Krisenmanagements und der Friedensstiftung liegen.
Background: Hybrids represent a cornerstone in the success story of breeding programs. The fundamental principle underlying this success is the phenomenon of hybrid vigour, or heterosis. It describes an advantage of the offspring as compared to the two parental lines with respect to parameters such as growth and resistance against abiotic or biotic stress. Dominance, overdominance or epistasis based models are commonly used explanations. Conclusion/Significance: The heterosis level is clearly a function of the combination of the parents used for offspring production. This results in a major challenge for plant breeders, as usually several thousand combinations of parents have to be tested for identifying the best combinations. Thus, any approach to reliably predict heterosis levels based on properties of the parental lines would be highly beneficial for plant breeding. Methodology/Principal Findings: Recently, genetic data have been used to predict heterosis. Here we show that a combination of parental genetic and metabolic markers, identified via feature selection and minimum-description-length based regression methods, significantly improves the prediction of biomass heterosis in resulting offspring. These findings will help furthering our understanding of the molecular basis of heterosis, revealing, for instance, the presence of nonlinear genotype-phenotype relationships. In addition, we describe a possible approach for accelerated selection in plant breeding.
Wie beständig ist der Mythos „Barack Obama“? Klar ist: Der neue Präsident tritt ein schweres Erbe an. Herausforderungen wie die Wirtschaftskrise, schwierige außen- und sicherheitspolitische Gegebenheiten und die Beziehungen zu Russland warten auf ihn. Der Autor, ein exzellenter Kenner der USA und ehemaliger Diplomat, beleuchtet die Situation der Vereinigten Staaten nach der Wahl.
Der gemeinsame Wandel der inselkeltischen Sprachen wie auch des Englischen vom vorwiegend synthetischen Typus zum vorwiegend analytischen Typus läßt sich vermutlich auf einen ca. 1500 Jahre dauernden intensiven Sprachenkontakt zwischen diesen Sprachen zurückführen. Heute ist das Englische die analytischste Sprache der Britischen Inseln und Irlands, gefolgt vom Walisischen, Bretonischen und Irischen. Letzteres ist von den genannten Sprachen noch am weitesten morphologisch komplex.
NATO-Streitkräfte sind weltweit im Einsatz. Dazu benötigen sie Material und die Industrie könnte sich eigentlich freuen. Doch der Markt für Rüstungsgüter aller Art ist kleiner geworden. Der Autor belegt an Beispielen deutlich, dass die Mitgliedstaaten der NATO sich bei ihren Verteidigungsagenden finanziell übernehmen und es ohne Kooperation keinen wirtschaftlichen Erfolg geben kann.
Menschenrechte auch in Afrika! : WT-Interview mit dem ugandischen Richter George W. Kanyeihamba
(2009)
Im Rahmen der alljährlichen Potsdamer Frühjahrsgespräche, die die Stiftung Entwicklung und Frieden in Kooperation mit WeltTrends durchführt, hatten wir Gelegenheit zu einem Gespräch mit dem ehemaligen Richter am Afrikanischen Gerichtshof für Menschenrechte und die Rechte der Völker, George W. Kanyeihamba aus Uganda.
Annotationen
(2009)
"Tatsächlich steht das offiziell verkündete Wahlergebnis nicht im Widerspruch zu einer im Mai landesweit durchgeführten Umfrage eines US-Forschungsinstituts. Dieses sah Ahmadinedschad klar vor seinem größten Konkurrenten Mussavi. Vermeintliche Quellen aus dem iranischen Innenministerium dagegen sprachen nach der Wahl von einem Erdrutschsieg Mussavis. Indizien für einen Betrug gibt es viele..."
The satellite era brings new challenges in the development and the implementation of potential field models. Major aspects are, therefore, the exploitation of existing space- and ground-based gravity and magnetic data for the long-term. Moreover, a continuous and near real-time global monitoring of the Earth system, allows for a consistent integration and assimilation of these data into complex models of the Earth’s gravity and magnetic fields, which have to consider the constantly increasing amount of available data. In this paper we propose how to speed up the computation of the normal equation in potential filed modeling by using local multi-polar approximations of the modeling functions. The basic idea is to take advantage of the rather smooth behavior of the internal fields at the satellite altitude and to replace the full available gravity or magnetic data by a collection of local moments. We also investigate what are the optimal values for the free parameters of our method. Results from numerical experiments with spherical harmonic models based on both scalar gravity potential and magnetic vector data are presented and discussed. The new developed method clearly shows that very large datasets can be used in potential field modeling in a fast and more economic manner.
Zeichnet sich die Außenpolitik der Großen Koalition durch „mangelndes Profil“ aus? Marieluise Beck belegt dies durch die deutsche Reaktion auf die Initiative für eine atomwaffenfreie Welt des US-Präsidenten. Auch bei den Debatten um Menschenrechte, den außenpolitischen Umgang mit China und Russland sowie die Verwendung von selektiven Sanktionen ist die Große Koalition den Anforderungen nicht gewachsen.
Europäische Zeitenwenden
(2009)
Blattgold : Machtkerle 09
(2009)
Europäische Brüche
(2009)
Vor 70 Jahren begann der Zweite Weltkrieg, ihm folgte der Kalte Krieg, der mit dem Jahr 89 abschloss. Die Folgen dieser europäischen Brüche sind bis heute zu spüren, vor allem für das Dreieck Warschau - Moskau - Berlin. Raus oder rein? Im Forum Afghanistan wird die Frage nach dem Engagement "des Westens" mit Carl Schmitt zugespitzt. Die tödliche Realität dieses Krieges setzt sich gegen die von der politischen Klasse vereinbarte Tabuisierung durch. Die Verlängerung des Mandates der Bundeswehr steht demnächst an. Die politische Debatte muss geführt werden. Jetzt und hier!
The phenolamines octopamine and tyramine control, regulate, and modulate many physiological and behavioral processes in invertebrates. Vertebrates possess only small amounts of both substances, and thus, octopamine and tyramine, together with other biogenic amines, are referred to as “trace amines.” Biogenic amines evoke cellular responses by activating G-protein-coupled receptors. We have isolated a complementary DNA (cDNA) that encodes a biogenic amine receptor from the American cockroach Periplaneta americana, viz., Peatyr1, which shares high sequence similarity to members of the invertebrate tyramine-receptor family. The PeaTYR1 receptor was stably expressed in human embryonic kidney (HEK) 293 cells, and its ligand response has been examined. Receptor activation with tyramine reduces adenylyl cyclase activity in a dose-dependent manner (EC50 350 nM). The inhibitory effect of tyramine is abolished by co-incubation with either yohimbine or chlorpromazine. Receptor expression has been investigated by reverse transcription polymerase chain reaction and immunocytochemistry. The mRNA is present in various tissues including brain, salivary glands, midgut, Malpighian tubules, and leg muscles. The effect of tyramine on salivary gland acinar cells has been investigated by intracellular recordings, which have revealed excitatory presynaptic actions of tyramine. This study marks the first comprehensive molecular, pharmacological, and functional characterization of a tyramine receptor in the cockroach.
The activity of vacuolar H+-ATPase (V-ATPase) in the apical membrane of blowfly (Calliphora vicina) salivary glands is regulated by the neurohormone serotonin (5-HT). 5-HT induces, via protein kinase A, the phosphorylation of V-ATPase subunit C and the assembly of V-ATPase holoenzymes. The protein phosphatase responsible for the dephosphorylation of subunit C and V-ATPase inactivation is not as yet known. We show here that inhibitors of protein phosphatases PP1 and PP2A (tautomycin, ocadaic acid) and PP2B (cyclosporin A, FK-506) do not prevent V-ATPase deactivation and dephosphorylation of subunit C. A decrease in the intracellular Mg2+ level caused by loading secretory cells with EDTA-AM leads to the activation of proton pumping in the absence of 5-HT, prolongs the 5-HT-induced response in proton pumping, and inhibits the dephosphorylation of subunit C. Thus, the deactivation of V-ATPase is most probably mediated by a protein phosphatase that is insensitive to okadaic acid and that requires Mg2+, namely, a member of the PP2C protein family. By molecular biological techniques, we demonstrate the expression of at least two PP2C protein family members in blowfly salivary glands. © 2009 Wiley Periodicals, Inc.
Schülerfirmen zeugen von der Innovationsfähigkeit der Schulen. Sie lassen auf Veränderungen des Unterrichts und des Selbstverständnisses von Schule und Kollegien schließen, denn sie stehen im Kontrast zum traditionellen Fachunterricht. Ihre Existenz sagt allerdings relativ wenig über die damit verbundene Qualität aus. So ist zu klären, welche Intentionen mit Qualitätssicherung verbunden sind. Darüber hinaus wird ein Qualitätsraster mit Indikatoren zur Analyse der Entwicklungsprozesse für Schülerfirmen zur Diskussion gestellt.
Schülerfirmen haben im Bereich Arbeitslehre in jüngster Zeit an Bedeutung gewonnen. Die Autoren stellen im Basisartikel des vorliegenden Heftes Lernen. Gewinn verschiedene Formen von Schülerfirmen vor und erläutern Probleme bei der Sicherung der Lernqualität. Diese beziehen sich einerseits auf die optimale Förderung arbeitsrelevanter Basiskompetenzen der Schüler und andererseits auf das Erreichen der curricularen Ziele der Arbeitslehre, insbesondere hinsichtlich der technischen und ökonomischen Bildung sowie der Berufsorientierung. Zur Optimierung sind Lehrplankorrekturen, weitere Erfahrungen mit Schülerfirmen und die Unterstützung der Fachdidaktik notwendig. Wichtig sind zudem eine kollegiale Kooperation und Vernetzung an den Lernorten. Die Verfasser führen darüber hinaus in die Beiträge des vorliegenden Heftes ein.
Die in den Materialien thematisierte Schülerfirma Pausenschmaus wurde als Prototyp für Lehr- und Lernzwecke modelliert. Die didaktische Modellvorstellung beruht auf Analysen existierender Schülerfirmen und bezieht sich auf die Forumsbeiträge zur Qualitätssicherung in diesem Heft. Das Material gibt einerseits für den Unterricht wie für Lehrerfortbildung einen exemplarischen Orientierungsrahmen zur Gestaltung eigener Schülerfirmen, anderseits ist es Grundlage für komplexe Aufgabenstellungen zur arbeitsorientierten Bildung, wie sie im gesonderten Beitrag am Beispiel eines konkreten unternehmerischen Problems ausgeführt werden. Die Darstellungen im Material sind situativ angelegt, um somit Schülerinnen und Schüler an Prozesse und Strukturen von Unternehmen und damit befassten betrieblichen Funktionen heranzuführen. Das Modellunternehmen hat einen Schwerpunkt im Catering.
Prediction of hybrid biomass in Arabidopsis thaliana by selected parental SNP and metabolic markers
(2009)
A recombinant inbred line (RIL) population, derived from two Arabidopsis thaliana accessions, and the corresponding testcrosses with these two original accessions were used for the development and validation of machine learning models to predict the biomass of hybrids. Genetic and metabolic information of the RILs served as predictors. Feature selection reduced the number of variables (genetic and metabolic markers) in the models by more than 80% without impairing the predictive power. Thus, potential biomarkers have been revealed. Metabolites were shown to bear information on inherited macroscopic phenotypes. This proof of concept could be interesting for breeders. The example population exhibits substantial mid-parent biomass heterosis. The results of feature selection could therefore be used to shed light on the origin of heterosis. In this respect, mainly dominance effects were detected.
The main objective of this study was to identify genomic regions involved in biomass heterosis using QTL, generation means, and mode-of-inheritance classification analyses. In a modified North Carolina Design III we backcrossed 429 recombinant inbred line and 140 introgression line populations to the two parental accessions, C24 and Col-0, whose F 1 hybrid exhibited 44% heterosis for biomass. Mid-parent heterosis in the RILs ranged from −31 to 99% for dry weight and from −58 to 143% for leaf area. We detected ten genomic positions involved in biomass heterosis at an early developmental stage, individually explaining between 2.4 and 15.7% of the phenotypic variation. While overdominant gene action was prevalent in heterotic QTL, our results suggest that a combination of dominance, overdominance and epistasis is involved in biomass heterosis in this Arabidopsis cross.
Background: Phylogenomic analyses recently became popular to address questions about deep metazoan phylogeny. Ribosomal proteins (RP) dominate many of these analyses or are, in some cases, the only genes included. Despite initial hopes, hylogenomic analyses including tens to hundreds of genes still fail to robustly place many bilaterian taxa. Results: Using the phylogenetic position of myzostomids as an example, we show that phylogenies derived from RP genes and mitochondrial genes produce incongruent results. Whereas the former support a position within a clade of platyzoan taxa, mitochondrial data recovers an annelid affinity, which is strongly supported by the gene order data and is congruent with morphology. Using hypothesis testing, our RP data significantly rejects the annelids affinity, whereas a platyzoan relationship is significantly rejected by the mitochondrial data. Conclusion: We conclude (i) that reliance of a set of markers belonging to a single class of macromolecular complexes might bias the analysis, and (ii) that concatenation of all available data might introduce conflicting signal into phylogenetic analyses. We therefore strongly recommend testing for data incongruence in phylogenomic analyses. Furthermore, judging all available data, we consider the annelid affinity hypothesis more plausible than a possible platyzoan affinity for myzostomids, and suspect long branch attraction is influencing the RP data. However, this hypothesis needs further confirmation by future analyses.
Background: Multidirectional interactions in social networks can have a profound effect on mate choice behavior; e.g., Poecilia mexicana males show weaker expression of mating preferences when being observed by a rival. This may be an adaptation to reduce sperm competition risk, which arises because commonly preferred female phenotypes will receive attention also from surrounding males, and/or because other males can copy the focal male's mate choice. Do P. mexicana males indeed respond to perceived sperm competition risk? We gave males a choice between two females and repeated the tests under one of the following conditions: (1) an empty transparent cylinder was presented (control); (2) another ("audience") male inside the cylinder observed the focal male throughout the 2nd part, or (3) the audience male was presented only before the tests, but could not eavesdrop during the actual choice tests (non-specific sperm competition risk treatments); (4) the focal male could see a rival male interact sexually with the previously preferred, or (5) with the non-preferred female before the 2nd part of the tests (specific sperm competition risk treatments). Results: The strength of individual male preferences declined slightly also during the control treatment (1). However, this decrease was more than two-fold stronger in audience treatment (2), i.e., with non-specific sperm competition risk including the possibility for visual eavesdropping by the audience male. No audience effect was found in treatments (3) and (5), but a weak effect was also observed when the focal male had seen the previously preferred female sexually interact with a rival male (treatment 4; specific sperm competition risk). Conclusion: When comparing the two 'non-specific sperm competition risk' treatments, a very strong effect was found only when the audience male could actually observe the focal male during mate choice [treatment (2)]. This suggests that focal males indeed attempt to conceal their mating preferences so as to prevent surrounding males from copying their mate choice. When there is no potential for eavesdropping [treatment (3)], non-specific specific sperm competition risk seems to play a minor or no role. Our results also show that P. mexicana males tend to share their mating effort more equally among females when the resource value of their previously preferred mate decreases after mating with a rival male (perceived specific sperm competition risk), but this effect is comparatively weak.
Covert shifts of attention are usually reflected in RT differences between responses to valid and invalid cues in the Posner spatial attention task. Such inferences about covert shifts of attention do not control for microsaccades in the cue target interval. We analyzed the effects of microsaccade orientation on RTs in four conditions, crossing peripheral visual and auditory cues with peripheral visual and auditory discrimination targets. Reaction time was generally faster on trials without microsaccades in the cue-target interval. If microsaccades occurred, the target-location congruency of the last microsaccade in the cuetarget interval interacted in a complex way with cue validity. For valid visual cues, irrespective of whether the discrimination target was visual or auditory, target-congruent microsaccades delayed RT. For invalid cues, target-incongruent microsaccades facilitated RTs for visual target discrimination, but delayed RT for auditory target discrimination. No reliable effects on RT were associated with auditory cues or with the first microsaccade in the cue-target interval. We discuss theoretical implications on the relation about spatial attention and oculomotor processes.
Blattgold : Heldendämmerung
(2009)
"Singe, Göttin, den Zorn des thymiotischen Sloterdijk ... Jetzt wo mit der Verleihung des Tapferkeitsordens die Belohnungsstruktur der Leistungsgesellschaft auch in der Bundeswehr angekommen ist, lohnt es sich vielleicht mal wieder, über Helden nachzudenken. Vorgedacht haben dies bekanntlich die Amerikaner..."
Wort und Strich
(2009)
Kooperative Beziehungen zu Russland sind angesichts der politisch-wirtschaftlichen Interessenlage, der geopolitischen Realitäten im Osten Europas und des geschichtlichen Hintergrundes in der deutschen politischen Klasse Konsens. Mit dem Begriff der strategischen Partnerschaft werden die deutsch-russischen Beziehungen immer wieder charakterisiert, d. h. diese Kooperation soll weit über die normalen Interessen Deutschlands hinausgehen und eine globalpolitische Dimension erreichen.
Die deutsche Außenpolitik hat seit dem 19. Jahrhundert bis zur Gegenwart viele Veränderungen erlebt. Lange stand Deutschland in einem angespannten Verhältnis zu den europäischen Ordnungen, doch nun ist es ein wichtiger Akteur der internationalen Gemeinschaft. Manfred Görtemaker, Professor für Neuere Geschichte aus Potsdam, zeichnet die wichtigsten Stationen dieser Entwicklung in seinem Beitrag nach.
Der Koordinator für deutsch-amerikanische Zusammenarbeit im Auswärtigen Amt, Karsten Voigt, attestiert der Außenpolitik der Großen Koalition eine erfolgreiche, solide Arbeit. Diese setzt die international geschätzte deutsche Kontinuität und Verlässlichkeit fort; auch in den zuletzt als schwierig empfundenen Beziehungen zu Russland und den USA.
Wie stabil ist die Außenpolitik der Großen Koalition? Aufgrund ihrer Position als stellvertretende außenpolitische Sprecherin der SPD ist es der Autorin möglich, neben den Gemeinsamkeiten auch die entscheidenden Unterschiede zu beleuchten. Vor dem Hintergrund mehrerer Beispiele, wie dem EU-Beitritt der Türkei, stellt sie den Konsens zwischen CDU/ CSU und SPD als fragil heraus.
Deutschland ist wegen seiner verlässlichen Außenpolitik ein weltweit angesehener Partner. Jedoch gelingt es der deutschen Außenpolitik momentan nicht, mit den Entwicklungen der globalisierten Welt Schritt zu halten. Bei wichtigen Themen hat die deutsche Regierung zu selten versucht, Stellung zu beziehen. Die Fähigkeit zur friedlichen Konfliktlösung muss Hauptanliegen unserer Außenpolitik sein. Als Grundlage dafür muss ein ständiger Dialog auch mit den Ländern, die unsere Werte nicht teilen, vorangetrieben werden.
US-Präsident Barack Obama hat die ersten hundert Tage seiner Administration hinter sich. Wie Alexander Höse zeigt, waren diese von einigen Höhen und Tiefen gekennzeichnet; allein die globale Finanzkrise hat ihren Beitrag dazu geleistet. Der Autor gibt einen Überblick über Obamas vermeintlich neue Politik und zeigt, dass sich so viel doch nicht geändert hat.
"Nach der Gründung der DDR war es eine Gruppe deutscher Antifaschisten, die an der Spitze der diplomatischen Missionen des neuen Staates auch einen neuen Typ deutscher Repräsentanten verkörperten. Fortan waren es nicht nur ehemalige Mitarbeiter des nationalsozialistischen AA, die nun für Bonn auf internationalem Parkett agierten, sondern angesehene Antifaschisten [...]"
"Der 8. Mai hat es in sich. Es ist aber nicht nur die Geschichte. Die Woche vom 8. Mai war in diesem Jahr die 'Woche der Wahrheit' im Bundestag, eine Kristallkugel, die einen düsteren Blick in die Zukunft erlaubt. Das wurde durch zwei Ereignisse klar, die etwas verband, ohne dass sie zusammen geplant waren. [...]"
NATO in der Sinnkrise
(2009)
Abschaffen oder reformieren? Egal, wie die Frage beantwortet wird, die Zeit für die „alte“ NATO ist abgelaufen. Ob ihr ein strategischer Relaunch für das 21. Jahrhundert gelingt oder ob sie in den Bergen Afghanistan allmählich zerbröselt – das ist noch offen. Sicher ist jedoch, es bedarf der Debatte über die Zukunft dieser politisch-militärischen Organisation, von den Bürgern in allen NATO-Ländern und damit auch hier. Afghanistan, Abrüstung und Afrika sind weitere Themen dieses Heftes, das erneut zeigt, dass WeltTrends eine solide Plattform für streitbare Diskussionen um die deutsche Außenpolitik ist.
Die vier Buchrezensionenum die Islamische Republik Iran spiegeln die ganze Bandbreite des Dilemmas im Umgang mit dem politisch gewichtigsten und auch umstrittensten Land im Nahen Osten wider. Sie zeigen die tiefe Spaltung, die in der Publizistik gegenüber diesem Land existiert; sei es in der Presse oder Fachliteratur.
Im Juli 1979 begann unter dem Begriff „Sandinistische Revolution“ eine tief greifende Umgestaltung in Nicaragua. Diese fand weltweit starkes Interesse. Das „neue Nicaragua“ wurde zur Zielscheibe der Konservativen und zur neuen Ikone der Linken, die einen Sozialismus jenseits totalitärer Strukturen ersehnte. Nach zehn Jahren endete dieses Projekt. 30 Jahre danach diskutiert der Autor, der in jenen Jahren selbst in Nicaragua weilte, die Ursachen der Revolution, ihre Erfolge und ihr letztliches Scheitern.
Rezensionen
(2009)
21 Mitgliedstaaten der EU sind heute gleichzeitig auch Mitglieder der NATO. Das geografische und politische Europa ist, bis auf wenige Ausnahmen, von Staaten besetzt, die zumindest einer dieser Organisationen angehören. Die verteidigungspolitische Organisation NATO trifft auf das politische System EU mit wachsendem sicherheitspolitischem Anspruch. Vor diesem Hintergrund werden verschiedene Aspekte der Kooperation zwischen diesen beiden Organisationen näher beleuchtet.
"Der Tscheche Věněk Šilhan sagt heutigen Lesern in Deutschland meist nichts. Er hat als Ökonom mehrere Bücher und gewichtige Aufsätze verfasst. Auf dem berühmten Parteitag der KPTsch in Prag-Vysočany, der sich der militärischen Okkupation am 21. August 1968 widersetzte, wurde er in Abwesenheit des internierten Alexander Dubček zum geschäftsführenden Ersten Sekretär des ZK gewählt. Dadurch ist er zu einer der Symbolfiguren des Prager Frühlings geworden."
Konferenzberichte
(2009)
"Bis vor Kurzem hätte man das Buch von Reinhold Niebuhr als zeitgeschichtliches Dokument aus dem Kalten Krieg gelesen. Doch weit gefehlt: Die Krise der Gegenwart zeigt, dass die reine Lehre der sozialen Konstruktion nicht funktioniert, wenn sie die Beschränkungen einer realistischen Anthropologie nicht berücksichtigt..."
Annotationen
(2009)
"Dieses Buch lohnt sich deshalb zum Wiederlesen, weil etliche der Thesen Barbers sich in den letzten Jahren eindrucksvoll bewahrheitet haben. Der bekannte US-amerikanische Politikwissenschaftler, der an der Rutgers University lehrte und nun an der University of Maryland tätig ist, bewies eine nahezu prophetische Gabe..."
Leserbriefe
(2009)