X-ray structure of the Na+-coupled Glycine-Betaine symporter BetP from Corynebacterium glutamicum

Cellular membranes are important sites of interaction between cells and their environment. Among the multitude of macromolecular complexes embedded in these membranes, transporters play a particularly important role. These integral membrane proteins perform a number of vital functions that enable cell adaptation to changing environmental conditions. Osmotic stress is a major external stimulus for cells. Bacteria are frequently exposed to either hyperosmotic or hypoosmotic stress. Typical conditions for soil bacteria, such as Corynebacterium glutamicum, vary between dryness and sudden rainfall. Physical stimuli caused by osmotic stress have to be sensed and used to activate appropriate response mechanisms. Hypoosmotic stress causes immediate and uncontrolled influx of water. Cells counteract by instantly opening mechanosensitive channels, which act as emergency valves leading to fast efflux of small solutes out of the cell, therebydiminishing the osmotic gradient across the cell membrane. Hyperosmotic stress, on the other hand, results in water efflux. This is counterbalanced by an accumulation of small, osmotically active solutes in the cytoplasm, the so-called compatible solutes. They comprise a large variety of substances, including amino acids (proline), amino acid derivatives (betaine, ectoine), oligosaccharides (trehalose), and heterosides (glucosylglycerol). Osmoregulated transporters sense intracellular osmotic pressure and respond to hyperosmotic stress by facilitating the inward translocation of compatible solutes across the cell membrane, to restore normal hydration levels. This work presents the first X-ray structure of a member of the Betaine-Choline-Carnitine-Transporter (BCCT) family, BetP. This Na+-coupled symporter from Corynebacterium glutamicum is a highly effective osmoregulated and specific uptake system for glycine-betaine. X-ray structure determination was achieved using single wavelength anomalous dispersion (SAD) of selenium atoms. Selenium was incorporated into the protein during its expression in methione auxotrophic E. coli cells, grown in media supplemented with selenomethionine. SAD data with anomalous signal up to 5 Å led to the detection of 39 selenium sites, which were used to calculate the initial electron density map of the protein. Medium resolution and high data anisotropy made the structure determination of BetP a challenging task. A specific strategy for data anisotropy correction and a combination of various crystallographic programs were necessary to obtain an interpretable electron density map suitable for model building. The crystal structure of BetP shows a trimer with glycine-betaine bound in a three-fold cation-pi interaction built by conserved tryptophan residues. The bound substrate is occluded from both sides of the membrane and aromatic side chains line its transport pathway. Very interestingly, the structure reveals that the alpha-helical C-terminal domain, for which a chemo- and osmosensory function was elucidated by biochemical methods, interacts with cytoplasmic loops of an adjacent monomer. These unexpected monomer-monomer interactions are thought to be crucial for the activation mechanism of BetP, and a new atomic model combing biochemical results with the crystal structure is proposed. BetP is shown to have the same overall fold as three unrelated Na+-coupled symporters. While these were crystallised in either the outward- or inward-facing conformation, BetP reveals a unique intermediate state, opening new perspectives on the alternating access mechanism of transport

Influence of surface reflectivity on reflectorless electronic distance measurement and terrestrial laser scanning

The uncertainty of electronic distance measurement to surfaces rather than to dedicated precisionre flectors (reflectorless EDM) is afected by the entire system comprising instrument, atmosphere and surface. The impact of the latter is significant for applications like geodetic monitoring, high-precision surface modelling or laser scanner self-calibration. Nevertheless, it has not yet received sufficient attention and is not well understood. We have carried out an experimental investigation of the impact of surface reflectivity on the distance measurements of a terrestrial laser scanner. The investigation helps to clarify (i)whether variations of reflectivity cause systematic deviations of reflectorless EDM, and (ii) if so, whether it is possible and worth modelling these deviations. The results show that differences in reflectivity may actually cause systematic deviations of a few mm with diffusely re- flecting surfaces and even more with directionally reflecting ones. Using abivariate quadratic polynomial we were able to approximate these deviations as a function of measured distance and measured signal strength alone. Using this approximation to predict corrections, the deviations of the measurements could be reduced by about 70% in our experiment.We conclude that there is a systematic effect of surface reflectivity (or equivalently received signal strength) on the distance measurement and that it is possible to model and predict this effect. Integration into laser scanner calibration models may be beneficial for high precision applications. The results may apply to a broad range of instruments, not only to the specific laser scanner used herei

Movement Lawyering During a Crisis: How the Legal System Exploits the Labor of Activists and Undermines Movements

There is increasing recognition that the ableist trope “Justice is Blind” is a decades-long gaslighting of the American public, a distraction from the reality that our entire judicial system has always had a strict adherence to white supremacy. In the United States, the highest court continues to erode civil rights protections that were hard fought by Black Americans, many whose lives were taken during the journey. The legislature has codified laws that simultaneously extract wealth from communities of color and criminalize poverty. And the legal profession is one of the least diverse of any professional industry. Impartiality of legal systems, theory, and praxis is an illusion that we cannot afford to buy-into within our work toward a society with equitable distribution of resources and equal access to wellness and joy. This article aims to highlight how the inequities embedded within the legal system are exacerbated during public crises, and used to exploit the work of Black, indigenous, and other activists of color. The article will shed light on the ways in which traditional litigation strategies, resource allocation, and long-established ethics standards have undermined the work toward liberating historically oppressed communities in the United States. We will provide examples within the movement to defend Black lives, the movement to free our children from cages, and within the hurried push to release people from institutions in the height of the COVID-19 threat. The article will also discuss specific strategies that movement lawyers have successfully employed to shift power away from white supremacist institutions and into the communities with whom we are fighting alongside. We conclude with a call for lawyers and legal workers to think critically about how they leverage power structures within the legal field to work in tandem with movements during a crisis

Untersuchungen über die Chrysopiden des Bezirkes Scheibbs (Niederösterreich). Beitrag zur Kenntnis der Ökologie, Phänologie und Verbreitung der Chrysopiden Mitteleuropas (Neuroptera: Planipennia).

In etwa zehnjähriger Sammeltätigkeit wurden im Bezirk Scheibbs (Niederösterreich) 4048 Chrysopiden gesammelt, die sich auf 17 Spezies verteilen: Nothochrysa fulviceps, N. capitata, Hypochrysa nobilis, Chrysopa perla, C. dorsalis, C. septempunctata, C. phyllochroma, Anisochrysa flavifrons, A. ventralis, A. prasina, A. carnea, A. albolineata, Tjederina gracilis, Nineta flava, N. vittata, N. pallida und Chrysotropia ciliata. Basierend auf morphologischen, phänologischen und ökologischen Fakten, spricht alles dafür, dass die in letzter Zeit als Subspezies aufgefaßten Formen Anisochrysa prasina als eigenständige Spezies anzusehen sind. Die Aufsammlungsergebnisse werden in Tabellen und Diagrammen übersichtlich dargelegt. Jede einzelne Art wird in der Diskussion in ökologisch-phänologischer Blickrichtung besprochen.During a period of about ten years 4048 specimes of the neuropterous family Chrysopidae were collected in the region of Scheibbs (Lower Austria). The material comprises 17 species, namely Nothochrysa fulviceps, N. capitata, Hypochrysa nobilis, Chrysopa perla, C. dorsalis, C. septempunctata, C. phyllochroma, Anisochrysa flavifrons, A. ventralis, A. prasina, A. carnea, A. albolineata, Tjederina gracilis, Nineta flava, N. vittata, N. pallida and Chrysotropia ciliata. On the basis of ecological results Anisochrysa ventralis and Anisochrysa prasina appear to be two clearly distinct forms thus confirming the assumption of other authors that they represent to valis species. The results of collections are shown in tables and diagrams. The ecology and seasonal dispersion as well as the vertical and horizontal distribution of each species are discussed in detail

Observation of a local gravity potential isosurface by airborne lidar of Lake Balaton, Hungary

Airborne lidar is a remote sensing method commonly used for mapping surface topography in high resolution. A water surface in hydrostatic equilibrium theoretically represents a gravity potential isosurface. Here we compare lidar-based ellipsoidal water surface height measurements all around the shore of a major lake with a local high-resolution quasi-geoid model. The ellipsoidal heights of the 87 km2 we sampled all around the shore of the 597 km2 lake surface vary by 0.8m and strong spatial correlation with the quasi-geoid undulation was calculated (R2 = 0.91). After subtraction of the local geoid undulation from the measured ellipsoidal water surface heights, their variation was considerably reduced. Based on a network of water gauge measurements, dynamic water surface heights were also successfully corrected for. This demonstrates that the water surface heights of the lake were truly determined by the local gravity potential.We conclude that both the level of hydrostatic equilibrium of the lake and the accuracy of airborne lidar were sufficient for identifying the spatial variations of gravity potential

Analysis of mobile laser scanning data and multi-view image reconstruction

The combination of laser scanning (LS, active, direct 3D measurement of the object surface) and photogrammetry (high geometric and radiometric resolution) is widely applied for object reconstruction (e.g. architecture, topography, monitoring, archaeology). Usually the results are a coloured point cloud or a textured mesh. The geometry is typically generated from the laser scanning point cloud and the radiometric information is the result of image acquisition. In the last years, next to significant developments in static (terrestrial LS) and kinematic LS (airborne and mobile LS) hardware and software, research in computer vision and photogrammetry lead to advanced automated procedures in image orientation and image matching. These methods allow a highly automated generation of 3D geometry just based on image data. Founded on advanced feature detector techniques (like SIFT (Scale Invariant Feature Transform)) very robust techniques for image orientation were established (cf. Bundler). In a subsequent step, dense multi-view stereo reconstruction algorithms allow the generation of very dense 3D point clouds that represent the scene geometry (cf. Patch-based Multi-View Stereo (PMVS2)). Within this paper the usage of mobile laser scanning (MLS) and simultaneously acquired image data for an advanced integrated scene reconstruction is studied. For the analysis the geometry of a scene is generated by both techniques independently. Then, the paper focuses on the quality assessment of both techniques. This includes a quality analysis of the individual surface models and a comparison of the direct georeferencing of the images using positional and orientation data of the on board GNSS-INS system and the indirect georeferencing of the imagery by automatic image orientation. For the practical evaluation a dataset from an archaeological monument is utilised. Based on the gained knowledge a discussion of the results is provided and a future strategy for the integration of both techniques is proposed

RIGOROUS STRIP ADJUSTMENT OF AIRBORNE LASERSCANNING DATA BASED ON THE ICP ALGORITHM

Airborne Laser Scanning (ALS) is an efficient method for the acquisition of dense and accurate point clouds over extended areas. To ensure a gapless coverage of the area, point clouds are collected strip wise with a considerable overlap. The redundant information contained in these overlap areas can be used, together with ground-truth data, to re-calibrate the ALS system and to compensate for systematic measurement errors. This process, usually denoted as strip adjustment, leads to an improved georeferencing of the ALS strips, or in other words, to a higher data quality of the acquired point clouds. We present a fully automatic strip adjustment method that (a) uses the original scanner and trajectory measurements, (b) performs an on-the-job calibration of the entire ALS multisensor system, and (c) corrects the trajectory errors individually for each strip. Like in the Iterative Closest Point (ICP) algorithm, correspondences are established iteratively and directly between points of overlapping ALS strips (avoiding a time-consuming segmentation and/or interpolation of the point clouds). The suitability of the method for large amounts of data is demonstrated on the basis of an ALS block consisting of 103 strips