Langzeitbelastung von Weinbergsböden mit Cu beeinflusst die Stressresistenz der mikrobiellen Gemeinschaft

Eine lang andauernde Bodenbelastung führt häufig zur Akklimatisierung bzw. Adaptation von Mikroorganismen, weshalb negative Wirkungen der Belastung durch übliche Toxizitätstests mit Bodenorganismen nicht angezeigt werden. Dies kann selbst bei sehr hohen Schadstoffgehalten auftreten, die bei Experimenten mit frisch zugegebenem Schadstoff eindeutig zu negativen Effekten führen. Langzeitkontaminationen durch Cu treten in Weinbergsböden verbreitet auf; seit dem späten 19. Jahrhundert und mit Applikationsmaxima in den 1920er bis 1930er Jahren sowie in den 1950er Jahren werden Cu-haltige Fungizide dort angewendet. In der Folge haben Weinbergsböden hohe Gehalte an Cu akkumuliert; Cu-Gehalte liegen in Weinbergsböden der Moselregion im Mittel bei 170 mg kg-1 Boden. Die mikrobielle Abundanz und Aktivität in Böden mit Langzeitkontamination steht jedoch meist in keinem eindeutigen Zusammenhang zu der Höhe der Belastung. Grundlage dieser Studie war die Hypothese, dass die Vorbelastung der Böden mit Cu zu einer erhöhten Empfindlichkeit gegenüber zusätzlichem Stress führt, was sich in einer verminderten Resistenz und Resilienz der mikrobiellen Gemeinschaft ausdrückt. Um dies zu untersuchen, wurden zehn Weinbergsböden des Weinbaugebietes Mosel mit Cu-Gesamtgehalten zwischen 20 und 440 mg kg‑1 ausgewählt. Die Stressresistenz der mikrobiellen Gemeinschaft in diesen Böden wurde mithilfe des relativen Bodenstabilitäts-Index (relative soil stability index - RSSI) ermittelt. Dazu wurden die Böden in Laborexperimenten einer kurzzeitigen Hitzebehandlung als zusätzlichem, zweitem Stress ausgesetzt und nachfolgend Enzymaktivitäten der Dehydrogenase und alkalischen Phosphatase als Endo- und Exoenzyme über 15 Tage gemessen. Die Ergebnisse bestätigen, dass die vorhandene, mikrobielle Aktivität in den Böden in keinem Zusammenhang zu den Gehalten an Gesamt-Cu wie auch mobilem Cu steht. Zusätzlicher Stress bewirkte weitere Verminderungen der Enzymaktivitäten, die über den beobachteten Zeitraum in unterschiedlichem Maß wieder kompensiert wurden. Diese Parameter stehen zumindest teilweise in Zusammenhang mit der Cu-Belastung. Überraschenderweise waren die Resistenz, Resilienz und der RSSI positiv mit der Cu-Belastung korreliert; eine höhere Cu-Belastung induziert eine höhere Resistenz gegen zusätzlichen Stress. Es wird vermutet, dass die Langzeit-Kontamination zur Selektion einer stressresistenteren mikrobiellen Gemeinschaft geführt hat. Dies wird durch weitere Parameter überprüft

Photoswitching Mechanism of Cyanine Dyes

Photoswitchable fluorescent probes have been used in recent years to enable super-resolution fluorescence microscopy by single-molecule imaging.1-6 Among these probes are red carbocyanine dyes, which can be reversibly photoconverted between a fluorescent state and a dark state for hundreds of cycles, yielding several thousand detected photons per switching cycle, before permanent photobleaching occurs.7,8 While these properties make them excel-lent probes for super-resolution imaging, the mechanism by which cyanine dyes are photoconverted has yet to be determined. Such an understanding could prove useful for creating new photoswit-chable probes with improved properties. The photoconversion of red cyanine dyes into their dark states occurs upon illumination by red light and is facilitated by a primary thiol in solution,7,9 whereas agents with a secondary thiol do not support photoswitching. These observations suggest that the reactiv

Stakeholder Workshops Informing System Modeling—Analyzing the Urban Food–Water–Energy Nexus in Amman, Jordan

Large cities worldwide are increasingly suffering from a nexus of food, water, and energy supply challenges. This complex nexus can be analyzed with modern physico-economic system models. Only when practical knowledge from those affected, experts, and decision makers is incorporated alongside various other data sources, however, are the analyses suitable for policy advice. Here, we present a concept for “Sustainability Nexus Workshops” suitable for extracting and preparing relevant practical knowledge for nexus modeling and apply it to the case of Amman, Jordan. The experiences of the workshop participants show that, although water scarcity is the predominant resource problem in Jordan, there is a close connection between food, water, and energy as well as between resource supply and urbanization. To prevent the foreseeable significant degradation of water supply security, actions are needed across all nexus dimensions. The stakeholders demonstrate an awareness of this and suggest a variety of technical measures, policy solutions, and individual behavioral changes—often in combination. Improving the supply of food, water, and energy requires political and institutional reforms. In developing these, it must be borne in mind that the prevalent informal structures and illegal activities are both strategies for coping with nexus challenges and causes of them

Single-molecule imaging to characterise the transport mechanism of the Nuclear Pore Complex

In the eukaryotic cell, a large macromolecular channel, known as the Nuclear Pore Complex (NPC), mediates all molecular transport between the nucleus and cytoplasm. In recent years, single-molecule fluorescence (SMF) imaging has emerged as a powerful tool to study the molecular mechanism of transport through the NPC. More recently, techniques such as Single-Molecule Localisation Microscopy (SMLM) have enabled the spatial and temporal distribution of cargos, transport receptors and even structural components of the NPC to be determined with nanometre accuracy. In this protocol, we describe a method to study the position and/or motion of individual molecules transiting through the NPC with high spatial and temporal precision

Excitonic AND Logic Gates on DNA Brick Nanobreadboards

A promising application of DNA self-assembly is the fabrication of chromophore-based excitonic devices. DNA brick assembly is a compelling method for creating programmable nanobreadboards on which chromophores may be rapidly and easily repositioned to prototype new excitonic devices, optimize device operation, and induce reversible switching. Using DNA nanobreadboards, we have demonstrated each of these functions through the construction and operation of two different excitonic AND logic gates. The modularity and high chromophore density achievable via this brick-based approach provide a viable path toward developing information processing and storage systems

DNA-Controlled Excitonic Switches

Fluorescence resonance energy transfer (FRET) is a promising means of enabling information processing in nanoscale devices, but dynamic control over exciton pathways is required. Here, we demonstrate the operation of two complementary switches consisting of diffusive FRET transmission lines in which exciton flow is controlled by DNA. Repeatable switching is accomplished by the removal or addition of fluorophores through toehold-mediated strand invasion. In principle, these switches can be networked to implement any Boolean function

A SNAP-Tagged Derivative of HIV-1—A Versatile Tool to Study Virus-Cell Interactions

Fluorescently labeled human immunodeficiency virus (HIV) derivatives, combined with the use of advanced fluorescence microscopy techniques, allow the direct visualization of dynamic events and individual steps in the viral life cycle. HIV proteins tagged with fluorescent proteins (FPs) have been successfully used for live-cell imaging analyses of HIV-cell interactions. However, FPs display limitations with respect to their physicochemical properties, and their maturation kinetics. Furthermore, several independent FP-tagged constructs have to be cloned and characterized in order to obtain spectral variations suitable for multi-color imaging setups. In contrast, the so-called SNAP-tag represents a genetically encoded non-fluorescent tag which mediates specific covalent coupling to fluorescent substrate molecules in a self-labeling reaction. Fusion of the SNAP-tag to the protein of interest allows specific labeling of the fusion protein with a variety of synthetic dyes, thereby offering enhanced flexibility for fluorescence imaging approaches

Quantitative Multicolor Super-Resolution Microscopy Reveals Tetherin HIV-1 Interaction

Virus assembly and interaction with host-cell proteins occur at length scales below the diffraction limit of visible light. Novel super-resolution microscopy techniques achieve nanometer resolution of fluorescently labeled molecules. The cellular restriction factor tetherin (also known as CD317, BST-2 or HM1.24) inhibits the release of human immunodeficiency virus 1 (HIV-1) through direct incorporation into viral membranes and is counteracted by the HIV-1 protein Vpu. For super-resolution analysis of HIV-1 and tetherin interactions, we established fluorescence labeling of HIV-1 proteins and tetherin that preserved HIV-1 particle formation and Vpu-dependent restriction, respectively. Multicolor super-resolution microscopy revealed important structural features of individual HIV-1 virions, virus assembly sites and their interaction with tetherin at the plasma membrane. Tetherin localization to micro-domains was dependent on both tetherin membrane anchors. Tetherin clusters containing on average 4 to 7 tetherin dimers were visualized at HIV-1 assembly sites. Combined biochemical and super-resolution analysis revealed that extended tetherin dimers incorporate both N-termini into assembling virus particles and restrict HIV-1 release. Neither tetherin domains nor HIV-1 assembly sites showed enrichment of the raft marker GM1. Together, our super-resolution microscopy analysis of HIV-1 interactions with tetherin provides new insights into the mechanism of tetherin-mediated HIV-1 restriction and paves the way for future studies of virus-host interactions

Patient experiences of psychological therapy for depression: a qualitative metasynthesis

Background Globally, national guidelines for depression have prioritised evidence from randomised controlled trials and quantitative meta-analyses, omitting qualitative research concerning patient experience of treatments. A review of patient experience research can provide a comprehensive overview of this important form of evidence and thus enable the voices and subjectivities of those affected by depression to have an impact on the treatments and services they are offered. This review aims to seek a comprehensive understanding of patient experiences of psychological therapies for depression using a systematic and rigorous approach to review and synthesis of qualitative research. Method PsychINFO, PsychARTICLES, MEDLINE, and CINAHL were searched for published articles using a qualitative approach to examine experiences of psychological therapies for depression. All types of psychological therapy were included irrespective of model or modes of delivery (e.g. remote or in person; group or individual). Each article was assessed following guidance provided by the Critical Appraisal Skill Programme tool. Articles were entered in full into NVIVO and themes were extracted and synthesized following inductive thematic analysis. Results Thirty-seven studies, representing 671 patients were included. Three main themes are described; the role of therapy features and setting; therapy processes and how they impact on outcomes; and therapy outcomes (benefits and limitations). Subthemes are described within these themes and include discussion of what works and what’s unhelpful; issues integrating therapy with real life; patient preferences and individual difference; challenges of undertaking therapy; influence of the therapist; benefits of therapy; limits of therapy and what happens when therapy ends. Conclusions Findings point to the importance of common factors in psychotherapies; highlight the need to assess negative outcomes; and indicate the need for patients to be more involved in discussions and decisions about therapy, including tailoring therapy to individual needs and taking social and cultural contexts into account

Super-Resolution Dynamic Imaging of Dendritic Spines Using a Low-Affinity Photoconvertible Actin Probe

The actin cytoskeleton of dendritic spines plays a key role in morphological aspects of synaptic plasticity. The detailed analysis of the spine structure and dynamics in live neurons, however, has been hampered by the diffraction-limited resolution of conventional fluorescence microscopy. The advent of nanoscopic imaging techniques thus holds great promise for the study of these processes. We implemented a strategy for the visualization of morphological changes of dendritic spines over tens of minutes at a lateral resolution of 25 to 65 nm. We have generated a low-affinity photoconvertible probe, capable of reversibly binding to actin and thus allowing long-term photoactivated localization microscopy of the spine cytoskeleton. Using this approach, we resolve structural parameters of spines and record their long-term dynamics at a temporal resolution below one minute. Furthermore, we have determined changes in the spine morphology in response to pharmacologically induced synaptic activity and quantified the actin redistribution underlying these changes. By combining PALM imaging with quantum dot tracking, we could also simultaneously visualize the cytoskeleton and the spine membrane, allowing us to record complementary information on the morphological changes of the spines at super-resolution