scholarly journals Occurrence of Foldings of Plasma Membrane (β-Cytomembrane) in Cells of Pig's Carpal Organ as revealed by Electron Microscopy

Nature ◽  
1958 ◽  
Vol 181 (4607) ◽  
pp. 489-489 ◽  
Author(s):  
K. KUROSUMI ◽  
T. KITAMURA
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
In Cells

scholarly journals Nanoscale coupling of endocytic pit growth and stability

2019 ◽  
Vol 5 (11) ◽  
pp. eaax5775 ◽  
Author(s):  
Martin Lehmann ◽  
Ilya Lukonin ◽  
Frank Noé ◽  
Jan Schmoranzer ◽  
Cecilia Clementi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Computational Modeling ◽  
Cell Signaling ◽  
Physiological Function ◽  
Automated Tracking ◽  
Metastable Structures ◽  
In Cells

Clathrin-mediated endocytosis, an essential process for plasma membrane homeostasis and cell signaling, is characterized by stunning heterogeneity in the size and lifetime of clathrin-coated endocytic pits (CCPs). If and how CCP growth and lifetime are coupled and how this relates to their physiological function are unknown. We combine computational modeling, automated tracking of CCP dynamics, electron microscopy, and functional rescue experiments to demonstrate that CCP growth and lifetime are closely correlated and mechanistically linked by the early-acting endocytic F-BAR protein FCHo2. FCHo2 assembles at the rim of CCPs to control CCP growth and lifetime by coupling the invagination of early endocytic intermediates to clathrin lattice assembly. Our data suggest a mechanism for the nanoscale control of CCP growth and stability that may similarly apply to other metastable structures in cells.

Electron microscopy of endocardial cell populations

1978 ◽  
Vol 36 (2) ◽  
pp. 486-487
Author(s):  
T. G. Sarphie ◽  
C. R. Comer ◽  
D. J. Allen
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Cellular Transformation ◽  
Cell Populations ◽  
Cell Surfaces ◽  
Kb Cells ◽  
Dna Viruses ◽  
Cell Cycles ◽  
Ultrastructural Studies ◽  
Endocardial Cell

Previous ultrastructural studies have characterized surface morphology during norma cell cycles in an attempt to associate specific changes with specific metabolic processes occurring within the cell. It is now known that during the synthetic ("S") stage of the cycle, when DNA and other nuclear components are synthesized, a cel undergoes a doubling in volume that is accompanied by an increase in surface area whereby its plasma membrane is elaborated into a variety of processes originally referred to as microvilli. In addition, changes in the normal distribution of glycoproteins and polysaccharides derived from cell surfaces have been reported as depreciating after cellular transformation by RNA or DNA viruses and have been associated with the state of growth, irregardless of the rate of proliferation. More specifically, examination of the surface carbohydrate content of synchronous KB cells were shown to be markedly reduced as the cell population approached division Comparison of hamster kidney fibroblasts inhibited by vinblastin sulfate while in metaphase with those not in metaphase demonstrated an appreciable decrease in surface carbohydrate in the former.

Triple Fixation For Electron Microscopy

1968 ◽  
Vol 26 ◽  
pp. 90-91 ◽  
Author(s):  
M. A. Hayat
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Electron Beam ◽  
Plasma Membrane ◽  
Myelin Sheath ◽  
Good Deal ◽  
Granular Structure ◽  
Oxidizing Agent ◽  
Fixation Technique ◽  
Large Clusters

Potassium permanganate has been successfully employed to study membranous structures such as endoplasmic reticulum, Golgi, plastids, plasma membrane and myelin sheath. Since KMnO4 is a strong oxidizing agent, deposition of manganese or its oxides account for some of the observed contrast in the lipoprotein membranes, but a good deal of it is due to the removal of background proteins either by dehydration agents or by volatalization under the electron beam. Tissues fixed with KMnO4 exhibit somewhat granular structure because of the deposition of large clusters of stain molecules. The gross arrangement of membranes can also be modified. Since the aim of a good fixation technique is to preserve satisfactorily the cell as a whole and not the best preservation of only a small part of it, a combination of a mixture of glutaraldehyde and acrolein to obtain general preservation and KMnO4 to enhance contrast was employed to fix plant embryos, green algae and fungi.

Revisiting staining of biological samples for electron microscopy: perspectives for recent research

2021 ◽  
Author(s):  
Maren T. Kuchenbrod ◽  
Ulrich S. Schubert ◽  
Rainer Heintzmann ◽  
Stephanie Hoeppener
Keyword(s):  
Electron Microscopy ◽  
Biological Samples ◽  
Active Sites ◽  
In Cells

This review revisits staining protocols for electron microscopy focussing on the visualization of active sites, i.e. enzymes, metabolites or proteins, in cells and tissues, which were never established as standard protocols in electron microscopy.

The transcytotic pathway of an apical plasma membrane protein (B10) in hepatocytes is similar to that of IgA and occurs via a tubular pericentriolar compartment

1996 ◽  
Vol 109 (6) ◽  
pp. 1215-1227 ◽  
Author(s):  
I. Hemery ◽  
A.M. Durand-Schneider ◽  
G. Feldmann ◽  
J.P. Vaerman ◽  
M. Maurice
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Membrane Proteins ◽  
Membrane Protein ◽  
Apical Membrane ◽  
Rat Hepatocytes ◽  
Apical Plasma Membrane ◽  
Apical Surface ◽  
Plasma Membrane Protein ◽  
Microtubule Disruption

In hepatocytes, newly synthesized apical plasma membrane proteins are first delivered to the basolateral surface and are supposed to reach the apical surface by transcytosis. The transcytotic pathway of apical membrane proteins and its relationship with other endosomal pathways has not been demonstrated morphologically. We compared the intracellular route of an apical plasma membrane protein, B10, with that of polymeric IgA (pIgA), which is transcytosed, transferrin (Tf) which is recycled, and asialoorosomucoid (ASOR) which is delivered to lysosomes. Ligands and anti-B10 monoclonal IgG were linked to fluorochromes or with peroxidase. The fate of each ligand was followed by confocal and electron microscopy in polarized primary monolayers of rat hepatocytes. When fluorescent anti-B10 IgG and fluorescent pIgA were simultaneously endocytosed for 15–30 minutes, they both uniformly labelled a juxtanuclear compartment. By 30–60 minutes, they reached the bile canaliculi. Tf and ASOR were also routed to the juxtanuclear area, but their fluorescence patterns were more punctate. Microtubule disruption prevented all ligands from reaching the juxtanuclear area. This area corresponded, at least partially, to the localization of the mannose 6-phosphate receptor, an endosomal marker. By electron microscopy, the juxtanuclear compartment was made up of anastomosing tubules connected to vacuoles, and was organized around the centrioles. B10 and pIgA were mainly found in the tubules, whereas ASOR was segregated inside the vacuolar elements and Tf within thinner, recycling tubules. In conclusion, transcytosis of the apical membrane protein B10 occurs inside tubules similar to those carrying pIgA, and involves passage via the pericentriolar area. In the pericentriolar area, the transcytotic tubules appear to maintain connections with other endosomal elements where sorting between recycled and degraded ligands occurs.

scholarly journals Epiplasts: Membrane Skeletons and Epiplastin Proteins in Euglenids, Glaucophytes, Cryptophytes, Ciliates, Dinoflagellates, and Apicomplexans

mBio ◽  
2018 ◽  
Vol 9 (5) ◽  
Author(s):  
Ursula Goodenough ◽  
Robyn Roth ◽  
Thamali Kariyawasam ◽  
Amelia He ◽  
Jae-Hyeok Lee
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Amino Acid ◽  
Secondary Structure ◽  
Amino Acid Composition ◽  
Acid Composition ◽  
Random Coil ◽  
Cell Cortex ◽  
Tail Domain ◽  
Membrane Skeletons

ABSTRACTAnimals and amoebae assemble actin/spectrin-based plasma membrane skeletons, forming what is often called the cell cortex, whereas euglenids and alveolates (ciliates, dinoflagellates, and apicomplexans) have been shown to assemble a thin, viscoelastic, actin/spectrin-free membrane skeleton, here called the epiplast. Epiplasts include a class of proteins, here called the epiplastins, with a head/medial/tail domain organization, whose medial domains have been characterized in previous studies by their low-complexity amino acid composition. We have identified two additional features of the medial domains: a strong enrichment of acid/base amino acid dyads and a predicted β-strand/random coil secondary structure. These features have served to identify members in two additional unicellular eukaryotic radiations—the glaucophytes and cryptophytes—as well as additional members in the alveolates and euglenids. We have analyzed the amino acid composition and domain structure of 219 epiplastin sequences and have used quick-freeze deep-etch electron microscopy to visualize the epiplasts of glaucophytes and cryptophytes. We define epiplastins as proteins encoded in organisms that assemble epiplasts, but epiplastin-like proteins, of unknown function, are also encoded in Insecta, Basidiomycetes, andCaulobactergenomes. We discuss the diverse cellular traits that are supported by epiplasts and propose evolutionary scenarios that are consonant with their distribution in extant eukaryotes.IMPORTANCEMembrane skeletons associate with the inner surface of the plasma membrane to provide support for the fragile lipid bilayer and an elastic framework for the cell itself. Several radiations, including animals, organize such skeletons using actin/spectrin proteins, but four major radiations of eukaryotic unicellular organisms, including disease-causing parasites such asPlasmodium, have been known to construct an alternative and essential skeleton (the epiplast) using a class of proteins that we term epiplastins. We have identified epiplastins in two additional radiations and present images of their epiplasts using electron microscopy. We analyze the sequences and secondary structure of 219 epiplastins and present an in-depth overview and analysis of their known and posited roles in cellular organization and parasite infection. An understanding of epiplast assembly may suggest therapeutic approaches to combat infectious agents such asPlasmodiumas well as approaches to the engineering of useful viscoelastic biofilms.

Formation of chlamydospores in Gilbertella persicaria

1981 ◽  
Vol 59 (5) ◽  
pp. 908-928 ◽  
Author(s):  
Martha J. Powell ◽  
Charles E. Bracker ◽  
David J. Sternshein
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Acid Phosphatase ◽  
Light And Electron Microscopy ◽  
Multivesicular Bodies ◽  
Marker Enzyme ◽  
Transparent Layer ◽  
Thiamine Pyrophosphatase ◽  
Gilbertella Persicaria

The cytological events involved in the transformation of vegetative hyphae of the zygomycete Gilbertella persicaria (Eddy) Hesseltine into chlamydospores were studied with light and electron microscopy. Thirty hours after sporangiospores were inoculated into YPG broth, swellings appeared along the aseptate hyphae. Later, septa, traversed by plasmodesmata, delimited each end of the hyphal swellings and compartmentalized these hyphal regions as they differentiated into chlamydospores. Nonswollen regions adjacent to chlamydospores remained as isthmuses. Two additional wall layers appeared within the vegetative wall of the developing chlamydospores. An alveolate, electron-dense wall formed first, and then an electron-transparent layer containing concentrically oriented fibers formed between this layer and the plasma membrane. Rather than a mere condensation of cytoplasm, development and maturation of the multinucleate chlamydospores involved extensive cytoplasmic changes such as an increase in reserve products, lipid and glycogen, an increase and then disappearance of vacuoles, and the breakdown of many mitochondria. Underlying the plasma membrane during chlamydospore wall formation were endoplasmic reticulum, multivesicular bodies, vesicles with fibrillar contents, vesicles with electron-transparent contents, and cisternal rings containing the Golgi apparatus marker enzyme, thiamine pyrophosphatase. Acid phosphatase activity was localized cytochemically in a cisterna which enclosed mitochondria and in vacuoles which contained membrane fragments. Tightly packed membrane whorls and single membrane bounded sacs with finely granular matrices surrounding vacuoles were unique during chlamydospore development. Microbodies were rare in the mature chlamydospore, but endoplasmic reticulum was closely associated with lipid globules. As chlamydospores developed, the cytoplasm in the isthmus became highly vacuolated, lipid globules were closely associated with vacuoles, mitochondria were broken down in vacuoles, unusual membrane configurations appeared, and eventually the membranes degenerated. Unlike chlamydospores, walls of the isthmus did not thicken, but irregularly shaped appositions containing numerous channels formed at intervals on the inside of these walls. The pattern of cytoplasmic transformations during chlamydospore development is similar to events leading to the formation of zygospores and sporangiospores.

scholarly journals Initial events during phagocytosis by macrophages viewed from outside and inside the cell: membrane-particle interactions and clathrin.

1982 ◽  
Vol 94 (3) ◽  
pp. 613-623 ◽  
Author(s):  
J Aggeler ◽  
Z Werb
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Plasma Membranes ◽  
Cell Attachment ◽  
High Resolution Electron Microscopy ◽  
Peritoneal Macrophages ◽  
Coated Pits ◽  
Thin Sections ◽  
Particle Uptake ◽  
Freeze Dried

The initial events during phagocytosis of latex beads by mouse peritoneal macrophages were visualized by high-resolution electron microscopy of platinum replicas of freeze-dried cells and by conventional thin-section electron microscopy of macrophages postfixed with 1% tannic acid. On the external surface of phagocytosing macrophages, all stages of particle uptake were seen, from early attachment to complete engulfment. Wherever the plasma membrane approached the bead surface, there was a 20-nm-wide gap bridged by narrow strands of material 12.4 nm in diameter. These strands were also seen in thin sections and in replicas of critical-point-dried and freeze-fractured macrophages. When cells were broken open and the plasma membrane was viewed from the inside, many nascent phagosomes had relatively smooth cytoplasmic surfaces with few associated cytoskeletal filaments. However, up to one-half of the phagosomes that were still close to the cell surface after a short phagocytic pulse (2-5 min) had large flat or spherical areas of clathrin basketwork on their membranes, and both smooth and clathrin-coated vesicles were seen fusing with or budding off from them. Clathrin-coated pits and vesicles were also abundant elsewhere on the plasma membranes of phagocytosing and control macrophages, but large flat clathrin patches similar to those on nascent phagosomes were observed only on the attached basal plasma membrane surfaces. These resulted suggest that phagocytosis shares features not only with cell attachment and spreading but also with receptor-mediated pinocytosis.

Sign in / Sign up

Export Citation Format

Share Document