New Views of Cell and Tissue Cytoarchitecture: Embedment-Free Electron Microscopy and Biochemical Analysis

1986 ◽  
pp. 89-99
Author(s):  
Edward G. Fey ◽  
Sheldon Penman
Keyword(s):  
Electron Microscopy ◽  
Free Electron ◽  
Biochemical Analysis

scholarly journals Coherent transition radiation from attosecond electron pulses

2019 ◽  
Vol 205 ◽  
pp. 02018
Author(s):  
Maxim Tsarev ◽  
Peter Baum
Keyword(s):  
Electron Microscopy ◽  
Free Electron ◽  
Transition Radiation ◽  
Beam Diameter ◽  
Pump Probe ◽  
Coherent Transition Radiation ◽  
Electron Pulses ◽  
Velocity Mismatch

We show theoretically and by simulations how coherent transition radiation from tilted surfaces can be used for characterization of attosecond free-electron pulses such as used for pump-probe electron microscopy and diffraction. The tilted geometries eliminate velocity-mismatch and beam-diameter effects, providing sensitivity to attosecond times even for almost arbitrarily large beam diameters.

Tylosis in the Orkney Islands

1978 ◽  
Vol 10 (1) ◽  
pp. 1-6
Author(s):  
Veronica M. L. Muir
Keyword(s):  
Electron Microscopy ◽  
Biochemical Analysis ◽  
Extended Family ◽  
Normal Skin ◽  
Linkage Studies ◽  
Constructive Approach ◽  
Orkney Islands

SummaryThe familial condition of tylosis was found in a single extended family in the Orkney islands. Unlike other pedigrees described it has no association with carcinoma of the oesophagus. Various linkage studies have been suggested and pooling of available data would offer a more constructive approach. Electron microscopy suggests further biochemical analysis on affected and normal skin to elucidate the underlying factors causing hyperkeratinization, and possibly resulting in more sophisticated treatment for this irritable but harmless condition.

scholarly journals The Depolarization-Evoked, Ca2+-Dependent Release of Exosomes From Mouse Cortical Nerve Endings: New Insights Into Synaptic Transmission

2021 ◽  
Vol 12 ◽  
Author(s):  
Guendalina Olivero ◽  
Francesca Cisani ◽  
Danilo Marimpietri ◽  
Daniela Di Paolo ◽  
Maria Cristina Gagliani ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Flow Cytometry ◽  
Light Scattering ◽  
Biochemical Analysis ◽  
Nerve Terminals ◽  
Transmission Electron ◽  
Presynaptic Release ◽  
Presynaptic Nerve Terminals ◽  
Active Release

Whether exosomes can be actively released from presynaptic nerve terminals is a matter of debate. To address the point, mouse cortical synaptosomes were incubated under basal and depolarizing (25 mM KCl-enriched medium) conditions, and extracellular vesicles were isolated from the synaptosomal supernatants to be characterized by dynamic light scattering, transmission electron microscopy, Western blot, and flow cytometry analyses. The structural and biochemical analysis unveiled that supernatants contain vesicles that have the size and the shape of exosomes, which were immunopositive for the exosomal markers TSG101, flotillin-1, CD63, and CD9. The marker content increased upon the exposure of nerve terminals to the high-KCl stimulus, consistent with an active release of the exosomes from the depolarized synaptosomes. High KCl-induced depolarization elicits the Ca2+-dependent exocytosis of glutamate. Interestingly, the depolarization-evoked release of exosomes from cortical synaptosomes also occurred in a Ca2+-dependent fashion, since the TSG101, CD63, and CD9 contents in the exosomal fraction isolated from supernatants of depolarized synaptosomes were significantly reduced when omitting external Ca2+ ions. Differently, (±)-baclofen (10 µM), which significantly reduced the glutamate exocytosis, did not affect the amount of exosomal markers, suggesting that the GABAB-mediated mechanism does not control the exosome release. Our findings suggest that the exposure of synaptosomes to a depolarizing stimulus elicits a presynaptic release of exosomes that occurs in a Ca2+-dependent fashion. The insensitivity to the presynaptic GABAB receptors, however, leaves open the question on whether the release of exosomes could be a druggable target for new therapeutic intervention for the cure of synaptopathies.

scholarly journals Biochemical analysis and electron microscopy of human mitral valve collagen in patients with various etiologies of mitral valve diseases.

1983 ◽  
Vol 24 (4) ◽  
pp. 529-538 ◽  
Author(s):  
Ying-Shiung LEE ◽  
Fan-Yu LEE ◽  
Ar-Huey LU ◽  
Chau-Hsiung CHANG ◽  
Hsiu-Chin CHEN ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mitral Valve ◽  
Biochemical Analysis ◽  
Valve Diseases

Inelastic Scattering and Electron Spectroscopy

1977 ◽  
Vol 35 ◽  
pp. 692-695
Author(s):  
B. Jouffrey
Keyword(s):  
Electron Microscopy ◽  
Inelastic Scattering ◽  
Free Electron ◽  
Electron Spectroscopy ◽  
Energy Losses ◽  
Scattering Angle ◽  
Crystalline Materials ◽  
Inelastic Event ◽  
Contrast Preservation ◽  
Electron Excitations

The reasons for studying energy losses can be quite different. The motivations are often highly diversified even if searchers are electron microscopists For instance, the problem of useful penetration involves studying the question of chromatic blurring even if in many cases this effect is not sufficient for explaining the limitations in penetration. The formation of damage (direct knock-on and ionization) is interesting in many ways. In electron microscopy an important point is also the contrast preservation in an inelastic event. This point is related to the useful penetratior (principally in crystalline materials). If that is rather well understood in the case of potentials which are not localized (1) (plasmons and single quasi free electron excitations), it is not so clear in the case of localized interactions as electron phonon ones (2,3,4) or inner shell excitations even if the scattering angle is quite small. However the understanding of this contrast preservation is fundamental.

scholarly journals Cryo-EM structure of C9ORF72–SMCR8–WDR41 reveals the role as a GAP for Rab8a and Rab11a

2020 ◽  
Vol 117 (18) ◽  
pp. 9876-9883 ◽  
Author(s):  
Dan Tang ◽  
Jingwen Sheng ◽  
Liangting Xu ◽  
Xiechao Zhan ◽  
Jiaming Liu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Biochemical Analysis ◽  
Direct Interaction ◽  
Gtpase Activating Protein ◽  
Structural Comparison ◽  
Genetic Origin ◽  
Hexanucleotide Repeat ◽  
And Function ◽  
Arginine Finger ◽  
Lateral Sclerosis

A massive intronic hexanucleotide repeat (GGGGCC) expansion in C9ORF72 is a genetic origin of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Recently, C9ORF72, together with SMCR8 and WDR41, has been shown to regulate autophagy and function as Rab GEF. However, the precise function of C9ORF72 remains unclear. Here, we report the cryogenic electron microscopy (cryo-EM) structure of the human C9ORF72–SMCR8–WDR41 complex at a resolution of 3.2 Å. The structure reveals the dimeric assembly of a heterotrimer of C9ORF72–SMCR8–WDR41. Notably, the C-terminal tail of C9ORF72 and the DENN domain of SMCR8 play critical roles in the dimerization of the two protomers of the C9ORF72–SMCR8–WDR41 complex. In the protomer, C9ORF72 and WDR41 are joined by SMCR8 without direct interaction. WDR41 binds to the DENN domain of SMCR8 by the C-terminal helix. Interestingly, the prominent structural feature of C9ORF72–SMCR8 resembles that of the FLNC–FNIP2 complex, the GTPase activating protein (GAP) of RagC/D. Structural comparison and sequence alignment revealed that Arg147 of SMCR8 is conserved and corresponds to the arginine finger of FLCN, and biochemical analysis indicated that the Arg147 of SMCR8 is critical to the stimulatory effect of the C9ORF72–SMCR8 complex on Rab8a and Rab11a. Our study not only illustrates the basis of C9ORF72–SMCR8–WDR41 complex assembly but also reveals the GAP activity of the C9ORF72–SMCR8 complex.

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