The Three Dimensionality of Cell Membranes: Lamellar to Cubic Membrane Transition as Investigated by Electron Microscopy

2012 ◽  
pp. 317-343 ◽  
Author(s):  
Ketpin Chong ◽  
Yuru Deng
Keyword(s):  
Electron Microscopy ◽  
Cell Membranes ◽  
Cubic Membrane

scholarly journals THE MECHANISM OF THE NEPHRIDIAL APPARATUS OF PARAMECIUM MUL TIMICRONUCLEATUM

1968 ◽  
Vol 37 (1) ◽  
pp. 139-146 ◽  
Author(s):  
Alan E. Organ ◽  
Eugene C. Bovee ◽  
Theodore L. Jahn ◽  
Duncan Wigg ◽  
James R. Fonseca
Keyword(s):  
Electron Microscopy ◽  
Excretory Pore ◽  
High Speed ◽  
Cell Membranes ◽  
Recent Analysis ◽  
Opposite Wall ◽  
Active Contraction ◽  
High Speed Cinematography ◽  
Excretory Canal

Recent analysis of the mechanism of the nephridial apparatus of Paramecium multimicronucleatum by high-speed cinematography (300 fps at x 250) confirms the observations by electron microscopy (Schneider, 1960) that once the pore is opened, the vesicle is invaginated by adjacent cytoplasm and is emptied by collapsing under pressure from that cytoplasm, aided perhaps by pressure of the fibrils which anchor the ampullae to the excretory canal. There is no indication of active contraction of the vesicle or its membrane. There is no permanent pore to the vesicle. The vesicle is closed by a sealing of the ruptured membrane where it is in contact with the pellicular excretory canal. At onset of expulsion of vesicular fluid the membrane across the basal opening of the excretory canal is ripped along one semicircular portion of the excretory pore and is driven up against the opposite wall as a flap while the water rushes out. A constriction of the vesicular and cell membranes at the base of the excretory canal reseals the opening.

scholarly journals THE STRUCTURE OF THE YOLK OF THE HEN'S EGG AS STUDIED BY ELECTRON MICROSCOPY

1961 ◽  
Vol 11 (1) ◽  
pp. 207-225 ◽  
Author(s):  
Ruth Bellairs
Keyword(s):  
Electron Microscopy ◽  
Fine Structure ◽  
Low Power ◽  
Phase Contrast ◽  
Cell Membranes ◽  
Protein Component ◽  
Hen’S Egg ◽  
True Structure

A description of the fine structure of the yolk of the unincubated hen's egg has been provided, which will serve as a basis for further studies on yolk digestion. The gross components of the yolk (that is, free-floating lipid drops, yellow and white yolk spheres together with their enclosed lipid subdroplets, and aqueous protein fluid) could be recognized by phase contrast and low power electron microscopy. The majority of the lipid drops, whether free floating or enclosed within yolk spheres, were composed of particles about 30 to 60 A in diameter. The protein component of the yolk was found to consist of round profiles about 250 A in diameter. The surfaces of the yolk spheres were of three types, and it is difficult to decide which represents the true structure although reasons are given for believing that yolk spheres are not normally enclosed by membranes identical with cell membranes.

scholarly journals Adenosinetriphosphatase Activity in the Cell Membranes of Kidney Tubule Cells

1958 ◽  
Vol 4 (6) ◽  
pp. 765-770 ◽  
Author(s):  
Herman W. Spater ◽  
Alex B. Novikoff ◽  
Bertha Masek
Keyword(s):  
Electron Microscopy ◽  
Atpase Activity ◽  
Proximal Tubule ◽  
Cell Membranes ◽  
Proximal Tubules ◽  
Variable Degree ◽  
Kidney Tubule ◽  
Cytochemical Study ◽  
Altered Metabolism ◽  
Tubule Cells

This cytochemical study demonstrates high levels of apparent ATPase activity in the infolded cell membranes of the proximal tubules (dog, rat, human, mouse, monkey, and opossum) and ascending loops of Henle (dog, rat, human and, to a variable degree, mouse). Electron microscopy has shown (see Rhodin (1)) that these membranes separate adjacent cells where they interlock with one another by multiple cytoplasmic lamellae containing oriented mitochondria. The significance of the high ATPase activity is considered in relation to possible movements of the membranes and to "active transport" believed to occur there. In the rat, enzyme activity in the proximal tubule membranes does not survive formol-calcium fixation, and it is therefore necessary to use unfixed sections for its demonstration. However, in edematous rats with experimental nephrosis (induced by the injection of aminonucleoside or with antikidney serum) marked ATPase activity is exhibited in these membranes even after formol-calcium fixation. When proximal tubule or Henle loop cells of the dog acquire an altered metabolism, as indicated by accumulated lipide spheres or by "droplets," the infolded ATPase-rich membranes are no longer demonstrable.

scholarly journals Reovirus Forms Neo-Organelles for Progeny Particle Assembly within Reorganized Cell Membranes

mBio ◽  
2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Isabel Fernández de Castro ◽  
Paula F. Zamora ◽  
Laura Ooms ◽  
José Jesús Fernández ◽  
Caroline M.-H. Lai ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Viral Replication ◽  
Cell Membranes ◽  
Light And Electron Microscopy ◽  
Host Cells ◽  
Pharmacological Intervention ◽  
Genome Replication ◽  
Particle Assembly ◽  
Intermediate Compartment

ABSTRACTMost viruses that replicate in the cytoplasm of host cells form neo-organelles that serve as sites of viral genome replication and particle assembly. These highly specialized structures concentrate viral replication proteins and nucleic acids, prevent the activation of cell-intrinsic defenses, and coordinate the release of progeny particles. Despite the importance of inclusion complexes in viral replication, there are key gaps in the knowledge of how these organelles form and mediate their functions. Reoviruses are nonenveloped, double-stranded RNA (dsRNA) viruses that serve as tractable experimental models for studies of dsRNA virus replication and pathogenesis. Following reovirus entry into cells, replication occurs in large cytoplasmic structures termed inclusions that fill with progeny virions. Reovirus inclusions are nucleated by viral nonstructural proteins, which in turn recruit viral structural proteins for genome replication and particle assembly. Components of reovirus inclusions are poorly understood, but these structures are generally thought to be devoid of membranes. We used transmission electron microscopy and three-dimensional image reconstructions to visualize reovirus inclusions in infected cells. These studies revealed that reovirus inclusions form within a membranous network. Viral inclusions contain filled and empty viral particles and microtubules and appose mitochondria and rough endoplasmic reticulum (RER). Immunofluorescence confocal microscopy analysis demonstrated that markers of the ER and ER-Golgi intermediate compartment (ERGIC) codistribute with inclusions during infection, as does dsRNA. dsRNA colocalizes with the viral protein σNS and an ERGIC marker inside inclusions. These findings suggest that cell membranes within reovirus inclusions form a scaffold to coordinate viral replication and assembly.IMPORTANCEViruses alter the architecture of host cells to form an intracellular environment conducive to viral replication. This step in viral infection requires the concerted action of viral and host components and is potentially vulnerable to pharmacological intervention. Reoviruses form large cytoplasmic replication sites called inclusions, which have been described as membrane-free structures. Despite the importance of inclusions in the reovirus replication cycle, little is known about their formation and composition. We used light and electron microscopy to demonstrate that reovirus inclusions are membrane-containing structures and that the endoplasmic reticulum (ER) and the ER-Golgi intermediate compartment interact closely with these viral organelles. These findings enhance our understanding of the cellular machinery usurped by viruses to form inclusion organelles and complete an infectious cycle. This information, in turn, may foster the development of antiviral drugs that impede this essential viral replication step.

Electron Microscopy of the FBJ Osteosarcoma Virus

1969 ◽  
Vol 27 ◽  
pp. 384-385
Author(s):  
B. O. Biskis ◽  
M. P. Finkel
Keyword(s):  
Electron Microscopy ◽  
Bone Tumors ◽  
Cell Membranes ◽  
Virus Particles ◽  
Type C

Finkel, Biskis, and Jinkins reported extraction of a virus (FBJ) from a spontaneous mouse osteosarcoma, in 1966. Although FBJ virus contains the group-specine complement fixing antigen common to viruses of the leukemia-sarcoma complex, in 28 cell-free passages to date in mice it has produced only bone tumors.In sections of the tumors virus particles appear in extracellular spaces and budding from cell membranes (Fig. 1). Morphologically, FBJ is a Type C virus, as designated by W. Bernhard, and it would be called Muri virus, Sarcomatis according to recommendations of the Provisional Committee for Nomenclature of viruses.

Ultrastructural observations on stumpy (stm,) a new chondrodystrophic mutant in the mouse

Development ◽  
1977 ◽  
Vol 39 (1) ◽  
pp. 279-284
Author(s):  
D. R. Johnson
Keyword(s):  
Electron Microscopy ◽  
Light Microscopy ◽  
Tight Junctions ◽  
Cell Membranes ◽  
Mitotic Rate ◽  
Close Approximation ◽  
Old Mice ◽  
Wide Zone

Stumpy (stm) is a new chondrodystrophic mutant in the mouse. Light microscopy of cartilage reveals a slightly increased mitotic rate, more chondrocytes than is usual per lacuna and a wide zone of hypertrophy. Electron microscopy shows that many chondrocytes are in close approximation with some tight junctions: in cartilage from 14-day-old mice there is much interdigitation and folding of the cell membranes of adjacent chondrocytes.

Electron microscopy of cell membranes

BMJ ◽  
1978 ◽  
Vol 1 (6127) ◽  
pp. 1621-1621
Author(s):  
C. Jones
Keyword(s):  
Electron Microscopy ◽  
Cell Membranes

Fluoride- and drought-induced structural alterations of mesophyll and guard cells in cotyledons of jack pine (Pinus banksiana)

1987 ◽  
Vol 65 (11) ◽  
pp. 2310-2317 ◽  
Author(s):  
J. J. Zwiazek ◽  
Jennifer M. Shay
Keyword(s):  
Electron Microscopy ◽  
Sodium Fluoride ◽  
Pinus Banksiana ◽  
Cell Membranes ◽  
Light And Electron Microscopy ◽  
Guard Cells ◽  
Jack Pine ◽  
Mesophyll Cells ◽  
Structural Alterations ◽  
Microscopy Techniques

Fluoride- and drought-induced injuries to mesophyll and guard cells were studied in jack pine (Pinus banksiana Lamb.) cotyledons, using light and electron microscopy techniques. Most early structural alterations were similar in cells of fluoride- and water-stressed seedlings. Both treatments resulted in an appearance of lipid material in the cytoplasm during early stages of injury, suggesting damage to the cell membranes. Treatment with sodium fluoride also resulted in deposition of starch in chloroplasts. Guard cells were more resistant to both stresses than mesophyll cells. Both metabolic injury and collapse of neighbouring cells may be responsible for the opening of stomata in wilting, fluoride-treated seedlings.

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