Microscopy (Oxford, England)最新文献

Patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) who have been admitted to the intensive care unit (ICU) often face months of physical disability after discharge. To optimize recovery, it is important to understand the role of musculoskeletal alterations in critically ill patients infected with SARS-CoV-2. The main aim of the present study was to describe the presence and morphology of nemaline bodies found in the skeletal muscle tissue from critically ill patients infected with SARS-CoV-2. In n = 7 patients infected with SARS-CoV-2, ultrastructural characteristics of vastus lateralis muscle obtained on days 1-3 and days 5-8 following ICU admission were investigated in more detail with electron microscopy. Those muscle biopsies consistently showed variable degrees of myofiber necrosis and myofibrillar disorganization. In 4/7 (57%) patients on days 5-8, the Z-line material accumulated into nemaline bodies with a typical lattice-like appearance at higher magnification, similar to that found in nemaline myopathy. This study is the first to describe the disintegration of myofibrils and the accumulation of Z-line material into nemaline bodies in the skeletal muscle tissue obtained from critically ill coronavirus disease-19 patients following ICU admission, which should be interpreted primarily as a non-specific pathological response of extreme myofibrillar disintegration associated with myofiber necrosis.

This paper presents an approach for determining the sizes and three-dimensional (3D) positions of nanoparticles from a through-focus series of high-angle annular dark-field scanning transmission electron microscopy images. By assuming spherical particles with uniform density, the sizes and 3D positions can be derived via Wiener deconvolution using a series of kernels prepared by the convolution of the 3D point spread function of the electron beam and the 3D density distribution of spheres with different radii. This process is referred to as a model-based deconvolution. Four 3D datasets with a volume size of 148 × 148 × 560 nm3 were obtained from the four sets of 256 high-angle annular dark-field scanning transmission electron microscopy images of 256 × 256 pixels taken from the same field of view under the through-focus condition. The 3D positions and radii of 14 particles in each 3D dataset were derived using the model-based deconvolution for ∼8 min. The observation errors of the 3D position were estimated as σx ≅ σy ≅ 0.3 nm and σz < 1.6 nm.

Recent advances in volume electron microscopy (EM) have been driving our thorough understanding of the brain architecture. Volume EM becomes increasingly powerful when cells and their subcellular structures that are imaged in light microscopy are correlated to those in ultramicrographs obtained with EM. This correlative approach, called correlative light and volume electron microscopy (vCLEM), is used to link three-dimensional ultrastructural information with physiological data such as intracellular Ca2+ dynamics. Genetic tools to express fluorescent proteins and/or an engineered form of a soybean ascorbate peroxidase allow us to perform vCLEM using natural landmarks including blood vessels without immunohistochemical staining. This immunostaining-free vCLEM has been successfully employed in two-photon Ca2+ imaging in vivo as well as in studying complex synaptic connections in thalamic neurons that receive a variety of specialized inputs from the cerebral cortex. In this mini-review, we overview how volume EM and vCLEM have contributed to studying the developmental processes of the brain. We also discuss potential applications of genetic manipulation of target cells using clustered regularly interspaced short palindromic repeats-associated protein 9 and subsequent volume EM to the analysis of protein localization as well as to loss-of-function studies of genes regulating brain development. We give examples for the combinatorial usage of genetic tools with vCLEM that will further enhance our understanding of regulatory mechanisms underlying brain development.

The mechanisms of electron irradiation damage to epoxy resin samples were evaluated using their electron diffraction patterns and electron energy-loss spectra. Their electron diffraction patterns consisted of three indistinct halo rings. The halo ring corresponding to an intermolecular distance of ∼6.4 Å degraded rapidly. Such molecular-scale collapse could have been caused by cross-linking between molecular chains. The degree of electron irradiation damage to the samples changed with the accelerating voltage. The tolerance dose limit of the epoxy resin estimated from the intensity of the halo ring was found to be improved at a higher accelerating voltage. Changes in low-loss electron energy-loss spectra indicated that the mass loss of the epoxy resin was remarkable in the early stage of electron irradiation.

This paper proposes a method that provides a phase image related to the demagnetization field (Hd) within a thin-foil permanent magnet using electron holography. The observation of Hd remains a significant challenge because electron holography in principle allows only imaging of the magnetic flux density (B), which is a mixture of the contributions from magnetization (M), stray magnetic field (Hs) outside of the specimen and Hd inside of the specimen. The phase map approximating Hd, which was determined by processing of the electron holography observation from a Nd2Fe14B single-crystalline specimen, showed a good agreement with the prediction by micromagnetic theory. With respect to permanent magnets, this method can be applied to examinations about the coercivity mechanism, which is sensitive to the demagnetization field. Graphical Abstract.

Soft magnetic materials have low coercive fields and high permeability. Recently, nanocrystalline alloys obtained using annealing amorphous alloys have attracted much interest since nanocrystalline alloys with small grain sizes of tens of nanometers exhibit low coercive fields comparable to that of amorphous alloys. Since nanocrystalline soft magnetic materials attain remarkable soft magnetic properties by controlling the grain size, the crystal grains' microstructure has a substantial influence on the soft magnetic properties. In this research, we examined the magnetic properties of Fe-Si-B-P-Cu nanocrystalline soft magnetic alloys obtained by annealing amorphous alloys. During crystallization, the observation findings reveal the correlation between the generated microstructures and soft magnetic properties.

High-angle annular dark-field (HAADF) imaging and elemental mapping at the atomic scale by scanning transmission electron microscopy (STEM) combined with electron energy-loss spectroscopy (EELS) are widely used for material characterization, in which quantitative understanding of the contrast of the image is required. Here, we report an unexpected image contrast in the elemental mapping of rutile TiO2, where the Ti L2,3 map shows an anisotropic elliptical shape that extends along the long axis in the octahedral structure, while the atomic contrast of Ti columns in the HAADF image is almost circular. Multi-slice simulation reveals that unique electron channeling related to the rutile structure and the difference of the potentials between HAADF and EELS cause the different atomic contrasts in the two images.

Transmission electron microscopy (TEM) has been essential in defining the structural organization of the cell due to its ability to image cell structures at molecular resolution. However, the absence of colour has made it very difficult to compare the distributions and relationships of two or more types of biomolecules simultaneously if they lack clear morphological distinctions. Furthermore, single-channel information limits functional analysis, particularly in the nucleoplasm, where fibrillar material could be chromatin, ribonucleic acid or protein. Where specific stains exist to discriminate among these molecules, they cannot be combined because conventional TEM is a single-channel technology. A potential path around this barrier is through electron spectroscopic imaging (ESI). ESI can map the distributions of chemical elements within an ultrathin section. Here, we present methods to stain specific molecules with elements that ESI can visualize to enable multichannel electron microscopy.