The respiratory chain complex forms a supercomplex (SC) in the inner mitochondrial membrane. This complex facilitates the process of electron transfer to produce the proton gradient used to synthesize ATP. Understanding the precise structure of the SC is considered an important challenge. However, it has not yet been reported. The development of a Cryo-electron microscopy (EM) technique provides an effective way to obtain high-resolution micrographs to determine the high-resolution three-dimensional structure of biomolecules. In this brief review, the currently reported Cryo-EM structures of the mammalian respirasome have been described in order to establish a direction for further research in the respiratory system.

Immunoelectron microscopy using an antigen-antibody reaction in an electron microscope is a very useful tool to identify the components of a tissue in an electron microscope. Many researchers also use immunoelectron microscopy. Nonetheless, immunoelectron microscopy is rarely introduced systematically, and immunoelectron microscopy can be carried out without fully understanding the principles, and cases of poor understanding can often be seen in the vicinity. Therefore, in order to make it easier to understand, we will first introduce the principles of immunoelectron microscopy and describe practical methods.

The release of nanoscale membrane-bound vesicles is common in all three domains of life. These vesicles are involved in a variety of biological processes such as cell-to-cell communication, horizontal gene transfer, and substrate transport. Prokaryotes including bacteria and archaea release membrane vesicles (MVs) (20 to 400 nm in diameter) into their extracellular milieu. In spite of structural differences in cell envelope, both Gram-positive and negative bacteria produce MVs that contain the cell membrane of each bacterial species. Archaeal MVs characteristically show surface-layer encircling the vesicles. Filamentous fungi and yeasts as eukaryotic microbes produce bilayered exosomes that have varying electron density. Microbes also form intracellular vesicles and minicells that are similar to MVs and exosomes in shape. Electron and fluorescence microscopy could reveal the presence of DNA in MVs and exosomes. Given the biogenesis of extracellular vesicles from the donor cell, in situ high-resolution microscopy can provide insights on the structural mechanisms underlying the formation and release of microbial extracellular vesicles.

Multiple synaptic boutons (MSBs) have been reported to be synapse with two or more postsynaptic terminals in one presynaptic terminal. These MSBs are known to be increased by various brain stimuli. In the motor cortex, increased number of MSB was observed in both acrobat training (AC) model and traumatic brain injury (TBI) model. Interestingly one is a physiological stimuli and the other is pathological insult. The purpose of this study is to compare the connectivity of MSBs between AC model and TBI model in the cerebral motor cortex, based on the hypothesis that the connectivity of MSBs might be different according to the models. The motor cortex was dissected from perfused brain of each experimental animal, the samples were prepared for routine transmission electron microscopy. The 60~70 serial sections were mounted on the one-hole grid and MSB was analyzed. The 3-dimensional analysis revealed that 94% of MSBs found in AC model synapse two postsynaptic spines from same dendrite. But, 28% MSBs from TBI models synapse two postsynaptic spines from different dendrite. This imply that the MSBs observed in motor cortex of AC model and TBI model might have different circuits for the processing the information.

Since a transmembrane protein, TMEM16A, also called anoctamin 1 (ANO1), was identified as a bona fide calcium ($Ca^{2+}$)-activated chloride ($Cl^-$) channel (CaCC), there have been many reports on its expression and function. However, limited information on ANO1 expression and function in the brain is still available. In this study, we tried to reexamine expression patterns of ANO1 in the mouse cerebellum and further characterize ANO1-expressing components by immunohistochemical analyses. Strong ANO1 immunoreactivity was observed as large puncta in the granule cell layer and weak to moderate immunoreactivities were observed as small puncta in the molecular and Purkinje cell layers. Double-label experiments revealed that ANO1 did not colocalize with cerebellar neuronal population markers, such as anti-calbindin and anti-NeuN, while it colocalized or intermingled with a presynaptic marker, anti-synaptophysin. These results demonstrate that ANO1 is mainly localized at presynaptic terminals in the cerebellum and involved in synaptic transmission and modulation in cerebellar information processing.

The multiple length scale analysis of previously designed Fe-Mn-Al-C based low-density model alloys reveals the difference in ordered ${\kappa}-carbide$, $(Fe,Mn)_3AlC_x$, between Fe-25Mn-16Al-5.2C (at%) alloy and Fe-3Mn-10Al-1.2C (at%) alloy. For the former alloy composition consisting of fully austenite grains, ${\kappa}-carbide$ showed majorly cuboidal and minorly pancake morphology and its chemical composition was not changed through aging for 24 h and 168 h at $600^{\circ}C$. Meanwhile, for the isothermally annealed ferritic alloy system for 1 hr at 500 and $600^{\circ}C$, the dramatic change in the chemical composition of needle-shape ${\kappa}-carbide$, $(Fe,Mn)_3(Fe,Al)C_x$, was found. Here we address that the compositional fluctuations in the vicinity of the carbides are significantly controlled by abutting phase, either austenite or ferrite. Namely, the cooperative ordering of carbon and Al is an important factor contributing to carbide formation in the high-Mn and high-Al alloyed austenitic steel, while the carbon and Mn for the low-Mn and high Al alloyed ferritic steel.

The focused ion beam (FIB) method is widely used to prepare specimens for observation by transmission electron microscopy (TEM), which offers a wide variety of imaging and analytical techniques. TEM has played a significant role in material investigation. However, the FIB method induces amorphization due to bombardment with the high-energy gallium ($Ga^+$) ion beam. To solve this problem, electron beam induced deposition (EBID) is used to form a protective layer to prevent damage to the specimen surface. In this study, we introduce an optimized TEM specimen preparation procedure by comparing the EBID of carbon and tungsten as protective layers in FIB. The selection of appropriate EBID conditions for preparing specimens for TEM analysis is described in detail.

Carbon has numerous allotropes and various crystalline forms with full dimensionalities such as diamond, graphite, fullerenes, and carbon nanotubes leading a wide range of applications. Since the emerge of graphene consisting of a single atomic layer of carbon atoms, a fabrication of all-carbon-based device with combination of one-, two-, and three-dimensional carbons has become a hot issue. Here, we introduce an ultimate one-dimensional carbon atomic chain. Carbon atomic chains were experimentally created by removing atoms from monolayer graphene sheet under electron beam inside transmission electron microscope (TEM). A series of TEM images demonstrate the dynamics of carbon atomic chains over time from the formation, transformation, and then breakage.

Soft ferromagnetic materials are utilized for various electromagnetic devices such as magnetic recording heads and magnetic shielding. In situ observation of magnetic microstructures and domain wall motions are prerequisite for understanding and improving their magnetic properties. In this work, by the Fresnel (out-of-focus) method of Lorentz microscopy, we observe the domain wall motions of polycrystalline Ni/Ti thin film layers triggered by single-shot laser pulse. Random motions of domain walls were visualized at every single pulse.

Electron channeling contrast imaging (ECCI) is one of the imaging techniques in scanning electron microscopy based on a variation in electron backscattering yield depending on the direction of the primary electron beam with respect to the crystal lattice. The ECCI provides not only observation of the distribution of individual grains and grain boundaries but also identification of the defects such as dislocations, twins, and stacking faults. The ECCI at the interface between recrystallized and deformed region of shot peening treated nickel clearly demonstrates the microstructural evolution during the recrystallization including original grain boundaries, and thus can provide better insight into the recrystallization behavior.

One of the most important factors determining the properties of a material is its grain size. However, unclear grain boundaries in the image hinder an accurate measurement of grain size. We demonstrate that grain boundaries existing in the images obtained by scanning transmission electron microscopy (STEM) can be clearly distinguished by applying a Sobel filter to a tilting series of STEM images of a hydrogenation-disproportionation-desorption-recombination processed Nd2Fe14B magnet sample.