Gram-positive Streptomyces bacteria are profuse secretors of polypeptides using complex, yet unknown mechanisms. Many of their secretory proteins are proteases that play important roles in the acquisition of amino acids from the environment. Other proteases regulate cellular proteostasis. To begin dissecting the possible role of proteases in Streptomyces secretion, we applied a multi-omics approach. We probed the role of the 190 proteases of Streptomyces lividans strain TK24 in protein secretion in defined media at different stages of growth. Transcriptomics analysis revealed transcripts for 93% of these proteases and identified that 41 of them showed high abundance. Proteomics analysis identified 57 membrane-embedded or secreted proteases with variations in their abundance. We focused on 17 of these proteases and putative inhibitors and generated strains deleted of their genes. These were characterized in terms of their fitness, transcriptome and secretome changes. In addition, we performed a targeted analysis in deletion strains that also carried a secretion competent mRFP. One strain, carrying a deletion of the gene for the regulatory protease FtsH, showed significant global changes in overall transcription and enhanced secretome and secreted mRFP levels. These data provide a first multi-omics effort to characterize the complex regulatory mechanisms of protein secretion in Streptomyces lividans and lay the foundations for future rational manipulation of this process.Weniger anzeigen
Background Both typhoidal and non-typhoidal Salmonella infections remain a considerable cause of morbidity and mortality globally, and impose a major socio-economic burden worldwide. A key property of all pathogenic Salmonella strains is the ability to invade host cells and reside within an intracellular, vacuolar compartment called the Salmonella-containing vacuole (SCV). Although the SCV is involved in both immune-evasion and intracellular replication and spread within the host, information about the host:pathogen interactions at this interface are limited, in part due to the technical difficulties involved in purification of these vacuoles. While a number of column- or gradient-based methods have been applied, cross-contamination with other host cell organelles or rupture of the labile SCV membrane has further complicated efforts to successfully isolate SCVs.
Results Here, we report the isolation of intact SCVs using carbon-coated, paramagnetic nanoparticles. The approach permits rapid isolation of intact SCVs from human macrophages in vitro without involving numerous purification steps. Bacteria are pre-labeled with modified nanoparticles prior to infection, and at various times post-infection, host cells are lysed and intact pathogen-containing phagosomes are recovered after application of a mild magnetic field. Purified, intact SCVs isolated using this method were shown to display high levels of co-association of internalized Salmonella with the standard SCV markers Rab5 and LAMP-1 using both microscopic and protein based methods.
Conclusion The method described is highly efficient, robust and permits rapid isolation of intact SCVs from human macrophages without involving numerous purification steps. The method can also be applied to other intracellular pathogens that reside within a vacuole-like compartment within host cells. Future work using the approach should aid in identification and characterization of host factors associated with the membranes of such intracellular pathogens, which could potentially serve as pharmaceutical targets against intracellular pathogens residing within vacuoles.Weniger anzeigen
Das Working Paper setzt sich kritisch mit der in der Forschungsliteratur zur novela bizantina des Siglo de Oro vielfach vertretenen Auffassung auseinander, diese sei nichts anderes als eine Rekombination vorgängig codifizierter Elemente. Vor dem Hintergrund einer kommunikationsorientierten Gattungstheorie, wie sie im Anschluss an Michail Bachtin v.a. in den Rhetorical Genre Studies vertreten wird, stellt sich allerdings die Frage nach der kommunikativen Leistungsfähigkeit eines Textes, dessen generische Identität unklar ist. Diese Frage stellt sich umso dringlicher, als auf der Ebene der impliziten wie expliziten Poetik im Siglo de Oro ein ausgeprägtes Gattungsbewusstsein zu beobachten ist. Vor diesem Hintergrund skizziert das Working Paper Affektregimes, die mit den unterschiedlichen Gattungen jeweils in Verbindung gebracht wurden und führt so den Nachweis, dass und wie die drei Prosalanggattungen, die im Siglo de Oro die Interaktion von Oberschichten in einem unironischen Sinn verhandeln, die libros de caballerías, die libros de pastores und die novela bizantina, als distinkt wahrgenommen wurden. Dabei kommt es nicht darauf an, Gattungen als unverbrüchliche und streng umgrenzte Entitäten zu konturieren und schon gar nicht als transhistorische Konstanten, im Gegenteil: vielmehr bemisst sich in unserer Lesart die kommunikative Wirksamkeit von Gattungen nicht an ihren isolierbaren Elementen oder absoluten Eigenschaften, sondern an ihrem relationalen Profil im Gattungsgefüge der Zeit und ihrer daraus resultierenden je spezifischen Anschlussfähigkeit.Weniger anzeigen
We present the study of the dynamics of a two-ring waveguide structure with space-dependent coupling, linear gain and nonlinear absorption; the system that can be implemented in polariton condensates, optical waveguides and nanocavities. We show that by turning on and off local coupling between rings, one can selectively generate a permanent vortex in one of the rings. We find that due to the modulation instability, it is also possible to observe several complex nonlinear phenomena, including spontaneous symmetry breaking, stable inhomogeneous states with an interesting structure of currents flowing between rings, the generation of stable symmetric and asymmetric circular flows with various vorticities, etc. The latter can be created in pairs (for relatively narrow coupling length) or as a single vortex in one of the channels, which later alternates between channels.Weniger anzeigen
With over 72 years having elapsed since the liberation of the Nazi concentration and extermination camps, what is the current status of teaching about the Holocaust at German universities? What do students, within the framework of their studies, learn about the Holocaust and its aftermath? To what extent and in which disciplines is the topic taught? What special challenges arise from German responsibility for the Holocaust? Does the higher education system in Germany have any special features that affect the way of teaching? Up till now there have been no comprehensive studies of all these questions. Unlike the status and development of Holocaust education at secondary schools in Germany, teaching at German universities on the subject has rarely been a topic of academic research. The present study intends to close this gap, by ascertaining, describing, and pointing out special features and trends in the actual state of affairs of teaching about the Holocaust at universities in Germany. By means of a two-stage survey procedure, combining an empirical evaluation of academic calendars with a content analysis of interviews with experts, the status quo is described both quantitatively and qualitatively, thus creating a differentiated picture of academic teaching about the Holocaust in Germany.Weniger anzeigen
To achieve the 90-90-90 goals set by UNAIDS, the number of new HIV infections needs to decrease to approximately 500,000 by 2020. One of the ‘five pillars’ to achieve this goal is pre-exposure prophylaxis (PrEP). Truvada (emtricitabine-tenofovir) is currently the only medication approved for PrEP. Despite its advantages, Truvada is costly and requires individuals to adhere to the once-daily regimen. To improve PrEP, many next-generation regimen, including long-acting formulations, are currently investigated. However, pre-clinical testing may not guide candidate selection, since it often fails to translate into clinical efficacy. On the other hand, quantifying prophylactic efficacy in the clinic is ethically problematic and requires to conduct long (years) and large (N>1000 individuals) trials, precluding systematic evaluation of candidates and deployment strategies. To prioritize- and help design PrEP regimen, tools are urgently needed that integrate pharmacological-, viral- and host factors determining prophylactic efficacy. Integrating the aforementioned factors, we developed an efficient and exact stochastic simulation approach to predict prophylactic efficacy, as an example for dolutegravir (DTG). Combining the population pharmacokinetics of DTG with the stochastic framework, we predicted that plasma concentrations of 145.18 and 722.23nM prevent 50- and 90% sexual transmissions respectively. We then predicted the reduction in HIV infection when DTG was used in PrEP, PrEP ‘on demand’ and post-exposure prophylaxis (PEP) before/after virus exposure. Once daily PrEP with 50mg oral DTG prevented 99–100% infections, and 85% of infections when 50% of dosing events were missed. PrEP ‘on demand’ prevented 79–84% infections and PEP >80% when initiated within 6 hours after virus exposure and continued for as long as possible. While the simulation framework can easily be adapted to other PrEP candidates, our simulations indicated that oral 50mg DTG is non-inferior to Truvada. Moreover, the predicted 90% preventive concentrations can guide release kinetics of currently developed DTG nano-formulations.Weniger anzeigen
Research on the conjunction of business elites and sustainable development fascinates practitioners and international organizations but faces methodological and data collection challenges within academia. Firstly, studies on corporate sustainability have promptly increased but have been extremely focused on an organizational level of analysis, which inhibits figuring out whether business decisions have an impact at the macro or societal level. Secondly, major policy recommendations on sustainable development point to the creation of networks and partnerships among business elites, governments and civil organizations but it is largely ignored which specific type of network configuration goes along with sustainable development. Thirdly, the literature on sustainable development often considered business elites as homogenous and concentrated, even though conflicting views exist regarding aspects of sustainable development. Finally, the influence of business elites on environmental, social and economic policies has been more supposed than empirically demonstrated. Past research has been unable to overcome these challenges in part due to insufficient data clarifying the full breadth of business elite connections with political and civil organizations nationally and transnationally, and the lack of a combination of analytical tools for analyzing multilevel characteristics and actions. The present paper proposes a research agenda to comprehend the role of business elites in sustainable development. Future studies should use network analysis as leverage, uncover the networks among business and political elites, focus on Latin American economies and regions, bypass case studies and develop cross-national and transnational analysis, and turn to a combination of causal methods.Weniger anzeigen
Exosomes are defined as extracellular membrane vesicles, 30–150 nm in diameter, derived from all types of cells. They originate via endocytosis and then they are released through exocytosis to the extracellular space, being found in various biological fluids as well as in cell culture medium. In the last few years, exosomes have gained considerable scientific interest due to their potential use as biomarkers, especially in the field of cancer research. This report describes a method to isolate, quantify and identify serum- and cell culture-derived exosomes from dog samples, using small volumes (100 μL and 1 mL, respectively).Weniger anzeigen
Hyperbranched polyglycerol (hPG) has been used as a multivalent scaffold to develop a series of nanocarriers capable of high-affinity encapsulation of copper (Cu). A rationally selected set of Cu-complexing motifs has been conjugated to hPG hydroxyl groups to render the constructs potentially usable as exogenous sources of Cu for addressing different pathological conditions associated with Cu-deficiency. We have utilized a newly discovered route to attach Cu-binding domains exclusively within a hPG core by selective differentiation between the primary and secondary hydroxyl groups of the polyol. These hPG-derivatives were found to form a stable complex with Cu ions depending on the type of immobilized ligands and corresponding degree of functionalization. In addition, these Cu-bearing nano-complexes demonstrated moderately cationic surface charge resulting in adjustable protein-binding characteristics and low cellular toxicity profile. We envision that these Cu-loaded hPG nanocarriers can be used as a stable platform to transport the metal ion across the systemic circulation to supply bioavailable quantity of Cu in disease-afflicted tissues.Weniger anzeigen
The capability of lipid bilayers to exhibit fluid-phase behavior is a fascinating property, which enables, for example, membrane-associated components, such as lipids (domains) and transmembrane proteins, to diffuse within the membrane. These diffusion processes are of paramount importance for cells, as they are for example involved in cell signaling processes or the recycling of membrane components, but also for recently developed analytical approaches, which use differences in the mobility for certain analytical purposes, such as in-membrane purification of membrane proteins or the analysis of multivalent interactions. Here, models describing the Brownian motion of membrane inclusions (lipids, peptides, proteins, and complexes thereof) in model bilayers (giant unilamellar vesicles, black lipid membranes, supported lipid bilayers) are summarized and model predictions are compared with the available experimental data, thereby allowing for evaluating the validity of the introduced models. It will be shown that models describing the diffusion in freestanding (Saffman-Delbrück and Hughes-Pailthorpe-White model) and supported bilayers (the Evans-Sackmann model) are well supported by experiments, though only few experimental studies have been published so far for the latter case, calling for additional tests to reach the same level of experimental confirmation that is currently available for the case of freestanding bilayers.Weniger anzeigen
Climate simulations are the fuel to drive hydrological models that are used to assess the impacts of climate change and variability on hydrological parameters, such as river discharges, soil moisture, and evapotranspiration. Unlike with cars, where we know which fuel the engine requires, we never know in advance what unexpected side effects might be caused by the fuel we feed our models with. Sometimes we increase the fuel's octane number (bias correction) to achieve better performance and find out that the model behaves differently but not always as was expected or desired. This study investigates the impacts of projected climate change on the hydrology of the Upper Blue Nile catchment using two model ensembles consisting of five global CMIP5 Earth system models and 10 regional climate models (CORDEX Africa). WATCH forcing data were used to calibrate an eco-hydrological model and to bias-correct both model ensembles using slightly differing approaches. On the one hand it was found that the bias correction methods considerably improved the performance of average rainfall characteristics in the reference period (1970–1999) in most of the cases. This also holds true for non-extreme discharge conditions between Q20 and Q80. On the other hand, bias-corrected simulations tend to overemphasize magnitudes of projected change signals and extremes. A general weakness of both uncorrected and bias-corrected simulations is the rather poor representation of high and low flows and their extremes, which were often deteriorated by bias correction. This inaccuracy is a crucial deficiency for regional impact studies dealing with water management issues and it is therefore important to analyse model performance and characteristics and the effect of bias correction, and eventually to exclude some climate models from the ensemble. However, the multi-model means of all ensembles project increasing average annual discharges in the Upper Blue Nile catchment and a shift in seasonal patterns, with decreasing discharges in June and July and increasing discharges from August to November.Weniger anzeigen
Extra-tropical cyclones in the subantarctic play a central role in the poleward transport of heat and moisture into Antarctica, with the latter being a key component of the mass balance of the Antarctic ice sheet. As the climate in this region undergoes substantial changes, it is anticipated that the character of these synoptic features will change. There are a number of different methods used to identify and track cyclones, which can potentially lead to different conclusions as to cyclone variability and trends, and mechanisms which drive these features. Given this, it is timely to assess the level of consensus among 14 state-of-the-art cyclone identification and tracking methods. We undertake this comparison with the ERA-Interim data-set for the period 1979–2008 and find large differences in the number of tracks identified by different methods, but the spatial patterns of the system density broadly agree. Links between large-scale modes of variability, such as the Southern Annular Mode (SAM), and subantarctic cyclones as suggested in the literature are confirmed by our analysis. Trends in the number of cyclone tracks show a more diverse picture. Robust trends are identified by almost all methods for austral summer over the region south to 60°S, mainly due to the strong relation to SAM, whereas in austral winter the methods disagree in the statistical significance of the trends. The agreement among the methods is greater when the comparison is confined to the stronger cyclones. This is confirmed by a moisture flux analysis associated with these strong synoptic systems. Our results indicate that multiple cyclone identification and tracking methods should be used to obtain robust conclusions for trends in cyclone characteristics as well as their relation to the large-scale circulation in the subantarctic region.Weniger anzeigen
A new generation of library systems is about to replace the so-called integrated library systems, which are beginning to fade. The library services platforms Alma, FOLIO and Worldshare Management Services (WMS), which are already in productive operation in some places, were examined with regard to their suitability for use in German libraries. The technical framework conditions and characteristics of those library management systems were studied and inventorized, so that they could be evaluated according to objective criteria. Based on that evaluation, recommendations were drawn up for libraries. The foundation for the investigation is made up of three components: First, German libraries’ requirements in relation to the new generation of systems were distilled from a broad range of literature and categorized. Furthermore, interviews were conducted with experts, addressing questions of system administration. Also, a widely distributed user survey was carried out to collect opinions on the performance of the systems in productive operation. The systems that are already in productive operation (Alma and WMS) can be employed to implement standard processes and integration options so that standard tasks can be accomplished. However, there are still unresolved issues with regard to nationally established and cooperatively maintained systems (federation catalogs, Zeitschriftendatenbank, Elektronische Zeitschriftenbibliothek). The main advantage of library services platforms lies in the possibility of managing print and electronic resources in one system. The systems conform to German and European regulations and laws in security aspects, but providers still have to clarify their compliance regarding the General Data Protection Regulation (GDPR). Problems arise from cloud computing and the associated remote and distributed data storage: Libraries can access their own data through application programming interfaces only. Finally, no increases in efficiency or cost reductions have been achieved so far.Weniger anzeigen