A screening-compatible live cell fluorescence resonance energy transfer-based assay for modulation of Rho GTPase activity

Rho family GTPases are central regulators of cytoskeletal dynamics controlled by guanine nucleotide exchange factors (RhoGEFs) and GTPase-activating proteins (RhoGAPs). This protocol presents a workflow for a robust high-throughput compatible biosensor assay to analyze changes in Rho GTPase activity by these proteins in the native cellular environment. The procedure can be used for semi-quantitative comparison of GEF/GAP function and extended for analysis of additional modulators. The experimental design is applicable also to other monomolecular ratiometric FRET sensors. For complete details on the use and execution of this protocol, please refer to Müller et al. (2020)

Liquid Chromatographic Resolution and Bioassay of Napropamide Herbicide Enantiomers

The enantiomers of the herbicide napropamide (1) were separated on a ?g-scale using chiral liquid chromatography and submitted to a bioassay for herbicidal activity using a wheat germ test. Under these conditions, only one enantiomer showed herbicidal activity. The potential for reducing the application rate of pesticides by omitting isomeric ballast is discussed

Analyzing the cellular plasma membrane by fast and efficient correlative STED and platinum replica EM

The plasma membrane of mammalian cells links transmembrane receptors, various structural components, and membrane-binding proteins to subcellular processes, allowing inter- and intracellular communication. Therefore, membrane-binding proteins, together with structural components such as actin filaments, modulate the cell membrane in their flexibility, stiffness, and curvature. Investigating membrane components and curvature in cells remains challenging due to the diffraction limit in light microscopy. Preparation of 5–15-nm-thin plasma membrane sheets and subsequent inspection by metal replica transmission electron microscopy (TEM) reveal detailed information about the cellular membrane topology, including the structure and curvature. However, electron microscopy cannot identify proteins associated with specific plasma membrane domains. Here, we describe a novel adaptation of correlative super-resolution light microscopy and platinum replica TEM (CLEM-PREM), allowing the analysis of plasma membrane sheets with respect to their structural details, curvature, and associated protein composition. We suggest a number of shortcuts and troubleshooting solutions to contemporary PREM protocols. Thus, implementation of super-resolution stimulated emission depletion (STED) microscopy offers significant reduction in sample preparation time and reduced technical challenges for imaging and analysis. Additionally, highly technical challenges associated with replica preparation and transfer on a TEM grid can be overcome by scanning electron microscopy (SEM) imaging. The combination of STED microscopy and platinum replica SEM or TEM provides the highest spatial resolution of plasma membrane proteins and their underlying membrane and is, therefore, a suitable method to study cellular events like endocytosis, membrane trafficking, or membrane tension adaptations

Von Neumann entropy from unitarity

The von Neumann entropy is a key quantity in quantum information theory and, roughly speaking, quantifies the amount of quantum information contained in a state when many identical and independent (i.i.d.) copies of the state are available, in a regime that is often referred to as being asymptotic. In this Letter, we provide a new operational characterization of the von Neumann entropy which neither requires an i.i.d. limit nor any explicit randomness. We do so by showing that the von Neumann entropy fully characterizes single-shot state transitions in unitary quantum mechanics, as long as one has access to a catalyst—an ancillary system that can be reused after the transition—and an environment which has the effect of dephasing in a preferred basis. Building upon these insights, we formulate and provide evidence for the catalytic entropy conjecture, which states that the above result holds true even in the absence of decoherence. If true, this would prove an intimate connection between single-shot state transitions in unitary quantum mechanics and the von Neumann entropy. Our results add significant support to recent insights that, contrary to common wisdom, the standard von Neumann entropy also characterizes single-shot situations and opens up the possibility for operational single-shot interpretations of other standard entropic quantities. We discuss implications of these insights to readings of the third law of quantum thermodynamics and hint at potentially profound implications to holography

A Representation Theorem for Singular Integral Operators on Spaces of Homogeneous Type

Let (X,d,\mu) be a space of homogeneous type and E a UMD Banach space. Under the assumption mu({x})=0 for all x in X, we prove a representation theorem for singular integral operators on (X,d,mu) as a series of simple shifts and rearrangements plus two paraproducts. This gives a T(1) Theorem in this setting

Analyzing the cellular plasma membrane by fast and efficient correlative STED and platinum replica EM

The plasma membrane of mammalian cells links transmembrane receptors, various structural components, and membrane-binding proteins to subcellular processes, allowing inter- and intracellular communication. Therefore, membrane-binding proteins, together with structural components such as actin filaments, modulate the cell membrane in their flexibility, stiffness, and curvature. Investigating membrane components and curvature in cells remains challenging due to the diffraction limit in light microscopy. Preparation of 5–15-nm-thin plasma membrane sheets and subsequent inspection by metal replica transmission electron microscopy (TEM) reveal detailed information about the cellular membrane topology, including the structure and curvature. However, electron microscopy cannot identify proteins associated with specific plasma membrane domains. Here, we describe a novel adaptation of correlative super-resolution light microscopy and platinum replica TEM (CLEM-PREM), allowing the analysis of plasma membrane sheets with respect to their structural details, curvature, and associated protein composition. We suggest a number of shortcuts and troubleshooting solutions to contemporary PREM protocols. Thus, implementation of super-resolution stimulated emission depletion (STED) microscopy offers significant reduction in sample preparation time and reduced technical challenges for imaging and analysis. Additionally, highly technical challenges associated with replica preparation and transfer on a TEM grid can be overcome by scanning electron microscopy (SEM) imaging. The combination of STED microscopy and platinum replica SEM or TEM provides the highest spatial resolution of plasma membrane proteins and their underlying membrane and is, therefore, a suitable method to study cellular events like endocytosis, membrane trafficking, or membrane tension adaptations

Boundary Lubrication of Oxide Surfaces by Poly(L-lysine)- g -poly(ethylene glycol) (PLL- g -PEG) in Aqueous Media

In this work, we have explored the application of poly(L-lysine)-g-poly(ethylene glycol) (PLL-g-PEG) as an additive to improve the lubricating properties of water for metal-oxide-based tribo-systems. The adsorption behavior of the polymer onto both silicon oxide and iron oxide has been characterized by optical waveguide lightmode spectroscopy (OWLS). Several tribological approaches, including ultra-thin-film interferometry, the mini traction machine (MTM), and pin-on-disk tribometry, have been employed to characterize the frictional properties of the oxide tribo-systems in various contact regimes. The polymer appears to form a protective layer on the tribological interface in aqueous buffer solution and improves both the load-carrying and boundary-layer-lubrication properties of wate

Metabolic, mental and immunological effects of normoxic and hypoxic training in multiple sclerosis patients: a pilot study

Background: Physical activity might attenuate inflammation and neurodegeneration in multiple sclerosis (MS). Erythropoietin, which is produced upon exposure to hypoxia, is thought to act as a neuroprotective agent in MS. Therefore, we studied the effects of intermittent hypoxic training on activity energy expenditure, maximal workload, serum erythropoietin, and immunophenotype focusing on regulatory and IL-17A-producing T cells. Methods: We assigned 34 relapsing-remitting MS patients within a randomized, single blind, parallel-group study to either normoxic (NO) or hypoxic (HO) treadmill training, both 3 times/week for 1 h over 4 weeks (Clinicaltrials.gov identifier: NCT02509897). Before and after training, activity energy expenditure (metabolic chamber), maximal workload (incremental treadmill test), walking ability, depressive symptoms (Beck Depression Inventory I), serum erythropoietin concentrations, and immunophenotype of peripheral blood mononuclear cells (PBMCs) were assessed. Results: Energy expenditure did not change due to training in both groups, but was rather fueled by fat than by carbohydrate oxidation after HO training (P = 0.002). Maximal workload increased by 40 Watt and 42 Watt in the NO and HO group, respectively (both P < 0.0001). Distance patients walked in 6 min increased by 25 m and 27 m in the NO and HO group, respectively (NO P = 0.02; HO P = 0.01). Beck Depression Inventory score markedly decreased in both groups (NO P = 0.03; HO P = 0.0003). NO training shifted Treg subpopulations by increasing and decreasing the frequency of CD39(+) and CD31(+) Tregs, respectively, and decreased IL-17A-producing CD4(+) cells. HO training provoked none of these immunological changes. Erythropoietin concentrations were within normal range and did not significantly change in either group. Conclusion: 4 weeks of moderate treadmill training had considerable effects on fitness level and mood in MS patients, both under normoxic and hypoxic conditions. Additionally, NO training improved Th17/Treg profile and HO training improved fatty acid oxidation during exercise. These effects could not be attributed to an increase of erythropoietin

Interoperability in the OpenDreamKit project : the Math-in-the-Middle approach

OpenDreamKit - "Open Digital Research Environment Toolkit for the Advancement of Mathematics" - is an H2020 EU Research Infrastructure project that aims at supporting, over the period 2015-2019, the ecosystem of open-source mathematical software systems. OpenDreamKit will deliver a flexible toolkit enabling research groups to set up Virtual Research Environments, customised to meet the varied needs of research projects in pure mathematics and applications. An important step in the OpenDreamKit endeavor is to foster the interoperability between a variety of systems, ranging from computer algebra systems over mathematical databases to front-ends. This is the mission of the integration work package. We report on experiments and future plans with the Math-in-the-Middle approach. This architecture consists of a central mathematical ontology that documents the domain and xes a joint vocabulary, or even a language, going beyond existing systems such as OpenMath, combined with specifications of the functionalities of the various systems. Interaction between systems can then be enriched by pivoting around this architecture.Postprin