The sleeping beauty kissed awake: new methods in electron microscopy to study cellular membranes

2017 ◽  
Vol 474 (6) ◽  
pp. 1041-1053 ◽  
Author(s):  
Petr Chlanda ◽  
Jacomine Krijnse Locker
Keyword(s):  
Electron Microscopy ◽  
Cell Biology ◽  
Sleeping Beauty ◽  
Chemical Fixation ◽  
Preparation Methods ◽  
Complementary Method ◽  
The Past ◽  
New Methods ◽  
Technological Advances ◽  
Infected Cells

Electron microscopy (EM) for biological samples, developed in the 1940–1950s, changed our conception about the architecture of eukaryotic cells. It was followed by a period where EM applied to cell biology had seemingly fallen asleep, even though new methods with important implications for modern EM were developed. Among these was the discovery that samples can be preserved by chemical fixation and most importantly by rapid freezing without the formation of crystalline ice, giving birth to the world of cryo-EM. The past 15–20 years are hallmarked by a tremendous interest in EM, driven by important technological advances. Cryo-EM, in particular, is now capable of revealing structures of proteins at a near-atomic resolution owing to improved sample preparation methods, microscopes and cameras. In this review, we focus on the challenges associated with the imaging of membranes by EM and give examples from the field of host–pathogen interactions, in particular of virus-infected cells. Despite the advantages of imaging membranes under native conditions in cryo-EM, conventional EM will remain an important complementary method, in particular if large volumes need to be imaged.

scholarly journals Single-particle cryo-EM—How did it get here and where will it go

Science ◽  
2018 ◽  
Vol 361 (6405) ◽  
pp. 876-880 ◽  
Author(s):  
Yifan Cheng
Keyword(s):  
Electron Microscopy ◽  
Structural Biology ◽  
Single Particle ◽  
Electron Crystallography ◽  
The Past ◽  
Cryo Electron Microscopy ◽  
Technological Advances ◽  
The Future ◽  
Electron Cryotomography

Cryo–electron microscopy, or simply cryo-EM, refers mainly to three very different yet closely related techniques: electron crystallography, single-particle cryo-EM, and electron cryotomography. In the past few years, single-particle cryo-EM in particular has triggered a revolution in structural biology and has become a newly dominant discipline. This Review examines the fascinating story of its start and evolution over the past 40-plus years, delves into how and why the recent technological advances have been so groundbreaking, and briefly considers where the technique may be headed in the future.

Linking glutamate receptor movements and synapse function

Science ◽  
2020 ◽  
Vol 368 (6496) ◽  
pp. eaay4631 ◽  
Author(s):  
Laurent Groc ◽  
Daniel Choquet
Keyword(s):  
Synaptic Transmission ◽  
Glutamate Receptor ◽  
Dynamic Equilibrium ◽  
Brain Disease ◽  
Receptor Trafficking ◽  
Degradation Pathways ◽  
Neurotransmitter Receptor ◽  
The Past ◽  
New Methods ◽  
Technological Advances

Regulation of neurotransmitter receptor content at synapses is achieved through a dynamic equilibrium between biogenesis and degradation pathways, receptor stabilization at synaptic sites, and receptor trafficking in and out synapses. In the past 20 years, the movements of receptors to and from synapses have emerged as a series of highly regulated processes that mediate postsynaptic plasticity. Our understanding of the properties and roles of receptor movements has benefited from technological advances in receptor labeling and tracking capacities, as well as from new methods to interfere with their movements. Focusing on two key glutamatergic receptors, we review here our latest understanding of the characteristics of receptor movements and their role in tuning the efficacy of synaptic transmission in health and brain disease.

scholarly journals Digital Image Analysis Tools Developed by the Indiana O’Brien Center

2021 ◽  
Vol 12 ◽  
Author(s):  
Kenneth W. Dunn
Keyword(s):  
Image Analysis ◽  
Cell Biology ◽  
Multiphoton Microscopy ◽  
Optical Sectioning ◽  
Biomedical Image ◽  
The Past ◽  
New Methods ◽  
Analysis Tools ◽  
Subcellular Resolution

The scale and complexity of images collected in biological microscopy have grown enormously over the past 30 years. The development and commercialization of multiphoton microscopy has promoted a renaissance of intravital microscopy, providing a window into cell biology in vivo. New methods of optical sectioning and tissue clearing now enable biologists to characterize entire organs at subcellular resolution. New methods of multiplexed imaging support simultaneous localization of forty or more probes at a time. Exploiting these exciting new techniques has increasingly required biomedical researchers to master procedures of image analysis that were once the specialized province of imaging experts. A primary goal of the Indiana O’Brien Center has been to develop robust and accessible image analysis tools for biomedical researchers. Here we describe biomedical image analysis software developed by the Indiana O’Brien Center over the past 25 years.

scholarly journals Sufficient dimension reduction and prediction in regression

2009 ◽  
Vol 367 (1906) ◽  
pp. 4385-4405 ◽  
Author(s):  
Kofi P. Adragni ◽  
R. Dennis Cook
Keyword(s):  
Applied Sciences ◽  
Dimension Reduction ◽  
Principal Components ◽  
Sufficient Dimension Reduction ◽  
The Past ◽  
New Methods ◽  
Technological Advances ◽  
Broad Overview

Dimension reduction for regression is a prominent issue today because technological advances now allow scientists to routinely formulate regressions in which the number of predictors is considerably larger than in the past. While several methods have been proposed to deal with such regressions, principal components (PCs) still seem to be the most widely used across the applied sciences. We give a broad overview of ideas underlying a particular class of methods for dimension reduction that includes PCs, along with an introduction to the corresponding methodology. New methods are proposed for prediction in regressions with many predictors.

Education for General Practice—Worldwide Problems

1972 ◽  
Vol 2 (2) ◽  
pp. 171-181
Author(s):  
P. S. Byrne
Keyword(s):  
General Practice ◽  
General Practitioner ◽  
Vocational Training ◽  
Continuing Care ◽  
The Past ◽  
New Methods ◽  
Technological Advances ◽  
Recent Developments ◽  
Definition Of ◽  
Terminological Confusion

Although there is terminological confusion over the definition of general practitioner, it is agreed that there must be, in all systems, a “physician who provides personal primary and continuing care to individuals and families.” Factors influencing general practice include geography and urbanization, social pressures, technological advances, specialization within the hospital field, and cost–effectiveness. The general practitioner is a specialist in a special field who requires special training for his work. In the recent past departments of social medicine have been involved in the teaching of general practice. This has not been successful. Recent developments have dramatized the large number of special departments of general practice or family medicine throughout the world which are contributing much to teaching in the undergraduate period and in vocational training. They are also contributing to new methods of education and assessment which have wider applications. The past decade has seen the emergence of general practice as a special branch of medical education in its own right. The future is full of challenges to develop further and to create a new cadre of teachers in this field.

scholarly journals Looking back and looking forward: contributions of electron microscopy to the structural cell biology of gametes and fertilization

Open Biology ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 200186
Author(s):  
Ravi Teja Ravi ◽  
Miguel Ricardo Leung ◽  
Tzviya Zeev-Ben-Mordehai
Keyword(s):  
Electron Microscopy ◽  
Cell Biology ◽  
Assisted Reproductive Technologies ◽  
Electron Tomography ◽  
Reproductive Technologies ◽  
Practical Significance ◽  
Preparation Methods ◽  
Structural Cell ◽  
Levels Of Detail ◽  
Complex Membrane

Mammalian gametes—the sperm and the egg—represent opposite extremes of cellular organization and scale. Studying the ultrastructure of gametes is crucial to understanding their interactions, and how to manipulate them in order to either encourage or prevent their union. Here, we survey the prominent electron microscopy (EM) techniques, with an emphasis on considerations for applying them to study mammalian gametes. We review how conventional EM has provided significant insight into gamete ultrastructure, but also how the harsh sample preparation methods required preclude understanding at a truly molecular level. We present recent advancements in cryo-electron tomography that provide an opportunity to image cells in a near-native state and at unprecedented levels of detail. New and emerging cellular EM techniques are poised to rekindle exploration of fundamental questions in mammalian reproduction, especially phenomena that involve complex membrane remodelling and protein reorganization. These methods will also allow novel lines of enquiry into problems of practical significance, such as investigating unexplained causes of human infertility and improving assisted reproductive technologies for biodiversity conservation.

Electron Microscope Comparison of Freeze-Substitution and Conventional Chemical Fixation of Undecalificied Human Dentin

1976 ◽  
Vol 55 (3) ◽  
pp. 400-410
Author(s):  
Morris Lamar Hicks ◽  
J. David Brilliant ◽  
D.W. Foreman
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Freeze Substitution ◽  
Chemical Fixation ◽  
Preparation Methods ◽  
Human Dentin ◽  
Technique Comparison

Undecalcified human dentin was prepared for electron microscopy by conventional chemical fixation with alcoholic dehydration and by freeze-substitution with cryodehydration. Comparisons are reported concerning effects of different preparation methods. Morphology remained unaltered in the pre-dentin and mineralized matrices. The technique comparison permitted inferences regarding hydration states and relative amounts of protein in different areas of the odontoblast cell.

Ultrastructural Analysis of the Salivary Glands of Gromphadorhina Portentosa (Schaum)

1977 ◽  
Vol 35 ◽  
pp. 638-639
Author(s):  
P.J. Dailey
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Salivary Glands ◽  
Secretory Vesicles ◽  
The Past ◽  
Transmission Electron ◽  
Means Of Transmission ◽  
Gromphadorhina Portentosa ◽  
Scanning Electron ◽  
Topographical Relief

The structure of insect salivary glands has been extensively investigated during the past decade; however, none have attempted scanning electron microscopy (SEM) in ultrastructural examinations of these secretory organs. This study correlates fine structure by means of SEM cryofractography with that of thin-sectioned epoxy embedded material observed by means of transmission electron microscopy (TEM).Salivary glands of Gromphadorhina portentosa were excised and immediately submerged in cold (4°C) paraformaldehyde-glutaraldehyde fixative1 for 2 hr, washed and post-fixed in 1 per cent 0s04 in phosphosphate buffer (4°C for 2 hr). After ethanolic dehydration half of the samples were embedded in Epon 812 for TEM and half cryofractured and subsequently critical point dried for SEM. Dried specimens were mounted on aluminum stubs and coated with approximately 150 Å of gold in a cold sputtering apparatus.Figure 1 shows a cryofractured plane through a salivary acinus revealing topographical relief of secretory vesicles.

Study of the Molecular Architecture of Keratin Filaments by Electron Microscopy

1982 ◽  
Vol 40 ◽  
pp. 118-119
Author(s):  
U. Aebi ◽  
P. Rew ◽  
T.-T. Sun
Keyword(s):  
Electron Microscopy ◽  
Structural Organization ◽  
Cell Types ◽  
Structural Features ◽  
Molecular Architecture ◽  
The Past ◽  
Keratin Filaments ◽  
Different Types ◽  
10 Nm Filaments ◽  
Different Cell Types

Various types of intermediate-sized (10-nm) filaments have been found and described in many different cell types during the past few years. Despite the differences in the chemical composition among the different types of filaments, they all yield common structural features: they are usually up to several microns long and have a diameter of 7 to 10 nm; there is evidence that they are made of several 2 to 3.5 nm wide protofilaments which are helically wound around each other; the secondary structure of the polypeptides constituting the filaments is rich in ∞-helix. However a detailed description of their structural organization is lacking to date.

The Diagnosis of Viral Disease by Electron Microscopy

1982 ◽  
Vol 40 ◽  
pp. 270-273
Author(s):  
William B. McCombs ◽  
Cameron E. McCoy
Keyword(s):  
Electron Microscopy ◽  
Hospital Stay ◽  
Viral Infections ◽  
Medical Profession ◽  
Bacterial Pathogens ◽  
Viral Disease ◽  
Viral Pathogens ◽  
Academic Interest ◽  
The Past

Recent years have brought a reversal in the attitude of the medical profession toward the diagnosis of viral infections. Identification of bacterial pathogens was formerly thought to be faster than identification of viral pathogens. Viral identification was dismissed as being of academic interest or for confirming the presence of an epidemic, because the patient would recover or die before this could be accomplished. In the past 10 years, the goal of virologists has been to present the clinician with a viral identification in a matter of hours. This fast diagnosis has the potential for shortening the patient's hospital stay and preventing the administering of toxic and/or expensive antibiotics of no benefit to the patient.

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