13 research outputs found

    Longitudinal locomotion assessment to study neurodegeneration in C. elegans models of tauopathies

    Get PDF
    Tauopathies are a group of neurodegenerative diseases defined by the aggregation of abnormally phosphorylated protein tau. The cause for neurodegeneration observed in tauopathies is not known. The discovery of mutations in the gene encoding for tau in familial cases of FTDP-17, a hereditary tauopathy, emphasized the importance of tau in these diseases. This led to the creation of animal models expressing human tau containing mutations found in FTDP-17, recapitulating some of the aspects of the disease, including neurodegeneration and tau aggregation. Reports on the consequences of human tau expression in the neurons of C. elegans are partially contradictory, especially with regard to their locomotor phenotype. In this work, we replicated C. elegans models of tauopathies and performed immunohistochemical and locomotion assessments. We created 23 genomically integrated strains pan-neuronally expressing either wild type or mutated human tau. In agreement with published reports, immunohistochemistry revealed no difference between wild type or mutated human tau with regard to phosphorylation status. To obtain lifelong, longitudinal recordings of several hundred worms, we developed a novel worm tracking system which we termed Robot-Assisted Plate Imaging Device (RAPID). Using RAPID, we recorded the stimulated locomotor performance of human tau-expressing worms, exceeding the number of all reported observations combined by two orders of magnitude. Our data indicate no pronounced locomotor phenotype in those transgenic worms, arguing against the reported neurotoxic effect of tau in C. elegans

    X-ray micro-tomography for investigations of brain tissues on cellular level

    No full text
    X-ray imaging in absorption contrast mode is well established for hard tissue visualization. However, performance for lower density materials is limited due to a reduced contrast. Our aim is three-dimensional (3D) characterization of micro-morphology of human brain tissues down to (sub-)cellular resolution within a laboratory environment. Using the laboratory-based microtomography (μCT) system nanotom® m (GE Sensing &amp; Inspection Technologies GmbH, Wunstorf, Germany) and synchrotron radiation at the Diamond-Manchester Imaging Branchline I13-2 (Diamond Light Source, Didcot, UK), we have acquired 3D data with a resolution down to 0.45 μm for visualization of a human cerebellum specimen down to cellular level. We have shown that all selected modalities, namely laboratory-based absorption contrast micro-tomography (LBμCT), synchrotron radiation based in-line single distance phase contrast tomography (SDPR) and synchrotron radiation based single-grating interferometry (GI), can reach cellular resolution for tissue samples with a size in the mm-range. The results are discussed qualitatively in comparison to optical microscopy of haematoxylin and eosin (H&amp;E) stained sections. As phase contrast yields to a better data quality for soft tissues and in order to overcome restrictions of limited beamline access for phase contrast measurements, we have equipped the μCT system nanotom® m with a double-grating phase contrast set-up. Preliminary experimental results of a knee sample consisting of a bony part and a cartilage demonstrate that phase contrast data exhibits better quality compared to absorption contrast. Currently, the set-up is under adjustment. It is expected that cellular resolution would also be achieved. The questions arise (1) what would be the quality gain of laboratory-based phase contrast in comparison to laboratory-based absorption contrast tomography and (2) could laboratory-based phase contrast data provide comparable results to synchrotron radiation based phase contrast data.</p

    Computational cell quantification in the human brain tissues based on hard X-ray phase-contrast tomograms

    No full text
    Cell visualization and counting plays a crucial role in biological and medical research including the study of neurodegenerative diseases. The neuronal cell loss is typically determined to measure the extent of the disease. Its characterization is challenging because the cell density and size already differs by more than three orders of magnitude in a healthy cerebellum. Cell visualization is commonly performed by histology and fluorescence microscopy. These techniques are limited to resolve complex microstructures in the third dimension. Phase-contrast tomography has been proven to provide sufficient contrast in the three-dimensional imaging of soft tissue down to the cell level and, therefore, offers the basis for the three-dimensional segmentation. Within this context, a human cerebellum sample was embedded in paraffin and measured in local phase-contrast mode at the beamline ID19 (ESRF, Grenoble, France) and the Diamond Manchester Imaging Branchline I13-2 (Diamond Light Source, Didcot, UK). After the application of Frangi-based filtering the data showed sufficient contrast to automatically identify the Purkinje cells and to quantify their density to 177 cells per mm3 within the volume of interest. Moreover, brain layers were segmented in a region of interest based on edge detection. Subsequently performed histological analysis validated the presence of the cells, which required a mapping from the two-dimensional histological slices to the three-dimensional tomogram. The methodology can also be applied to further tissue types and shows potential for the computational tissue analysis in health and disease.</p

    Cerebral Corpora amylacea are dense membranous labyrinths containing structurally preserved cell organelles

    No full text
    Abstract Corpora amylacea are cell-derived structures that appear physiologically in the aged human brain. While their histological identification is straightforward, their ultrastructural composition and microenvironment at the nanoscale have remained unclear so far, as has their relevance to aging and certain disease states that involve the sequestration of toxic cellular metabolites. Here, we apply correlative serial block-face scanning electron microscopy and transmission electron tomography to gain three-dimensional insight into the ultrastructure and surrounding microenvironment of cerebral Corpora amylacea in the human brainstem and hippocampal region. We find that cerebral Corpora amylacea are composed of dense labyrinth-like sheets of lipid membranes, contain vesicles as well as morphologically preserved mitochondria, and are in close proximity to blood vessels and the glymphatic system, primarily within the cytoplasm of perivascular glial cells. Our results clarify the nature of cerebral Corpora amylacea and provide first hints on how they may arise and develop in the aging brain
    corecore