Structure of contact sites between the outer and inner mitochondrial membranes investigated by HVEM tomography

1996 ◽  
Vol 54 ◽  
pp. 966-967
Author(s):  
C.A. Mannella ◽  
K.F. Buttle ◽  
K.A. O‘Farrell ◽  
A. Leith ◽  
M. Marko
Keyword(s):  
Liver Mitochondrion ◽  
Adenine Nucleotide ◽  
Protein Complexes ◽  
Mitochondrial Membranes ◽  
Electron Microscopic ◽  
Contact Sites ◽  
Transmission Electron ◽  
Precursor Proteins ◽  
Membrane Contacts ◽  
And Function

Early transmission electron microscopy of plastic-embedded, thin-sectioned mitochondria indicated that there are numerous junctions between the outer and inner membranes of this organelle. More recent studies have suggested that the mitochondrial membrane contacts may be the site of protein complexes engaged in specialized functions, e.g., import of mitochondrial precursor proteins, adenine nucleotide channeling, and even intermembrane signalling. It has been suggested that the intermembrane contacts may be sites of membrane fusion involving non-bilayer lipid domains in the two membranes. However, despite growing interest in the nature and function of intramitochondrial contact sites, little is known about their structure.We are using electron microscopic tomography with the Albany HVEM to determine the internal organization of mitochondria. We have reconstructed a 0.6-μm section through an isolated, plasticembedded rat-liver mitochondrion by combining 123 projections collected by tilting (+/- 70°) around two perpendicular tilt axes. The resulting 3-D image has confirmed the basic inner-membrane organization inferred from lower-resolution reconstructions obtained from single-axis tomography.

Ultrastructural histocytopathology of spleen of rat (Rattus norvegicus) induced by fluoride toxicity

2013 ◽  
Vol 3 (4) ◽  
pp. 183-187
Author(s):  
Arbind Kumar ◽  
Sapna Kumari
Keyword(s):  
Electron Microscopy ◽  
Rattus Norvegicus ◽  
Dental Fluorosis ◽  
Abdominal Cavity ◽  
Treated Group ◽  
Skeletal Fluorosis ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Reticular Fibers ◽  
And Function

Drinking water is one of the largest sources of fluoride. Excessive intake of fluoride results in all the three forms of fluorosis viz. Dental fluorosis, skeletal fluorosis and Non-skeletal fluorosis. Our present experiment was designed to study the non-skeletal fluorosis. The experimental animal Rattus norvegicus were randomly distributed into two groups of eight animals each. One group was given gavages of NaF at 50mg/kg-bw/day for 60 days along with the diet and the other group was paired fed which served as control. After 60 days the animals of both the group were sacrificed by cervical dislocation, the abdominal cavity was opened and spleens were dissected out. The tissue was further processed for light microscopy, transmission electron microscopy and scanning electron microscopy and analysed. Both light microscopic and electron microscopic observations showed damage to the reticular cells and reticular fibers of the spleen in the fluoride treated group. This may adversely affect the structure and function of the spleen grossly inhibiting the antigenic reactions resulting into the declination of the immune power.

scholarly journals Phospholipid ebb and flow makes mitochondria go

2020 ◽  
Vol 219 (8) ◽  
Author(s):  
Michelle Grace Acoba ◽  
Nanami Senoo ◽  
Steven M. Claypool
Keyword(s):  
Protein Complexes ◽  
Lipid Transfer ◽  
Phospholipid Biosynthesis ◽  
Mitochondrial Membranes ◽  
Lipid Transfer Proteins ◽  
Physiological Functions ◽  
Contact Sites ◽  
Recent Advances ◽  
Cellular Integrity ◽  
Ebb And Flow

Mitochondria, so much more than just being energy factories, also have the capacity to synthesize macromolecules including phospholipids, particularly cardiolipin (CL) and phosphatidylethanolamine (PE). Phospholipids are vital constituents of mitochondrial membranes, impacting the plethora of functions performed by this organelle. Hence, the orchestrated movement of phospholipids to and from the mitochondrion is essential for cellular integrity. In this review, we capture recent advances in the field of mitochondrial phospholipid biosynthesis and trafficking, highlighting the significance of interorganellar communication, intramitochondrial contact sites, and lipid transfer proteins in maintaining membrane homeostasis. We then discuss the physiological functions of CL and PE, specifically how they associate with protein complexes in mitochondrial membranes to support bioenergetics and maintain mitochondrial architecture.

Heterogeneity of the composition and thickness of tracheal mucus in rats

1997 ◽  
Vol 273 (5) ◽  
pp. L1036-L1041 ◽  
Author(s):  
David E. Sims ◽  
Margaret M. Horne
Keyword(s):  
Electron Microscopic ◽  
Transmission Electron Microscopic Study ◽  
Transmission Electron ◽  
Muscle Region ◽  
Cellular Debris ◽  
The Mean ◽  
And Function ◽  
Tracheal Mucus ◽  
Trachealis Muscle

Inability to preserve airway mucus in situ has limited our understanding of its structure and function. This light- and transmission electron-microscopic study of rat tracheal mucus used a nonaqueous fixative that retains mucus (epiphase) over a lucent layer (hypophase). The fixative is a 1% solution of osmium tetroxide dissolved in a perfluorocarbon. The mean thickness of rat tracheal epiphase was 5 μm, with significant variation (0.1–50 μm) around the tracheal circumference. Tracheal mucus was thickest at the trachealis muscle region and contained cells, cellular debris, and a variable amount of surfactant and lipid, estimated at 4–16% of the total epiphase in five rats, with a mean composition of 9%. Lipid was observed on the surface of the epiphase, embedded within mucus, and at the epiphase-hypophase interface. Refined study of developmental, physiological, and pathological alterations to the airway coat may benefit from this approach.

Structure and function of Pet100p, a molecular chaperone required for the assembly of cytochrome c oxidase in Saccharomyces cerevisiae

2001 ◽  
Vol 29 (4) ◽  
pp. 436-441 ◽  
Author(s):  
D. Forsha ◽  
C. Church ◽  
P. Wazny ◽  
R. O. Poyton
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Molecular Chaperone ◽  
Mitochondrial Membrane ◽  
Protein Complexes ◽  
Structure And Function ◽  
Eukaryotic Cells ◽  
Mitochondrial Membranes ◽  
Inner Mitochondrial Membrane ◽  
And Function

The assembly of cytochrome c oxidase in the inner mitochondrial membranes of eukaryotic cells requires the protein products of a large number of nuclear genes. In yeast, some of these act globally and affect the assembly of several respiratory-chain protein complexes, whereas others act in a cytochrome c oxidase-specific fashion. Many of these yeast proteins have human counterparts, which when mutated lead to energy-related diseases. One of these proteins, Pet100p, is a novel molecular chaperone that functions to incorporate a subcomplex containing cytochrome c oxidase subunits VII, VIIa and VIII into holo-(cytochrome c oxidase). Here we report the topological disposition of Pet100p in the inner mitochondrial membrane and show that its C-terminal domain is essential for its function as a cytochrome c oxidase-specific ‘assembly facilitator’.

Cornified cell envelope assembly: a model based on electron microscopic determinations of thickness and projected density

1998 ◽  
Vol 111 (8) ◽  
pp. 1051-1060
Author(s):  
M. Jarnik ◽  
M.N. Simon ◽  
A.C. Steven
Keyword(s):  
Electron Microscopy ◽  
Cell Envelope ◽  
Protein Composition ◽  
Variable Number ◽  
Electron Microscopic ◽  
Protein Mass ◽  
Transmission Electron ◽  
Precursor Proteins ◽  
Scanning Transmission ◽  
Cornified Cell Envelope

In stratifying squamous epithelia, the cornified cell envelope (CE), a peripheral layer of crosslinked protein, is assembled sequentially from precursor proteins initially dispersed in the cytoplasm. Its major component is loricrin (37 kDa in mouse), which contributes from approx. 60% to >80% of the protein mass in different tissues. Despite its importance to the mechanical resilience and impenetrability of these tissues, detailed information has not been obtained on CE structure, even on such basic properties as its thickness or uniformity across a given CE or from tissue to tissue. To address this issue, we have studied CEs isolated from three murine epithelia, namely epidermis, forestomach and footpad, by electron microscopy of metal-shadowed specimens and scanning transmission electron microscopy (STEM) of unstained specimens. The former data reveal that the cytoplasmic surface is smoothly textured whereas the extracellular surface is corrugated, and that the average thickness is 15.3+/−1.2 nm, and strikingly uniform. Measurements of mass-per-unit-area from the STEM images yielded values of approx. 7.0+/−0.8 kDa/nm2, which were remarkably consistent over all three tissues. These data imply that the mature CE has a uniquely defined thickness. To explain its uniformity, we postulate that loricrin forms a molecular monolayer, not a variable number of multiple layers. In this scenario, the packing density is one loricrin monomer per 7 nm2, and loricrin should have an elongated shape, 2.5-3.0 nm wide by approx. 11 nm long. Moreover, we anticipate that any inter-tissue variations in the mechanical properties of CEs should depend more on protein composition and cross-linking pattern than on the thickness of the protein layer deposited.

A Reproducible Selective Stain for Cardiac Sarcoplasmic Reticulum

1974 ◽  
Vol 32 ◽  
pp. 214-215
Author(s):  
R. A. Waugh ◽  
J. R. Sommer
Keyword(s):  
Complex System ◽  
Electron Microscope ◽  
Sarcoplasmic Reticulum ◽  
Transmission Electron Microscope ◽  
Electron Microscopic ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Transmission Electron

Cardiac sarcoplasmic reticulum (SR) is a complex system of intracellular tubules that, due to their small size and juxtaposition to such electron-dense structures as mitochondria and myofibrils, are often inconspicuous in conventionally prepared electron microscopic material. This study reports a method with which the SR is selectively “stained” which facilitates visualizationwith the transmission electron microscope.

Transmission Electron Microscopy of Protein Macromolecules

1971 ◽  
Vol 29 ◽  
pp. 424-425
Author(s):  
Henry S. Slayter
Keyword(s):  
Biological Systems ◽  
Metal Vapor ◽  
Resolving Power ◽  
Electron Microscopic ◽  
Chemical Methods ◽  
Molecular Weights ◽  
The Past ◽  
Physical Chemical ◽  
Transmission Electron

Electron microscopic methods have been applied increasingly during the past fifteen years, to problems in structural molecular biology. Used in conjunction with physical chemical methods and/or Fourier methods of analysis, they constitute powerful tools for determining sizes, shapes and modes of aggregation of biopolymers with molecular weights greater than 50, 000. However, the application of the e.m. to the determination of very fine structure approaching the limit of instrumental resolving power in biological systems has not been productive, due to various difficulties such as the destructive effects of dehydration, damage to the specimen by the electron beam, and lack of adequate and specific contrast. One of the most satisfactory methods for contrasting individual macromolecules involves the deposition of heavy metal vapor upon the specimen. We have investigated this process, and present here what we believe to be the more important considerations for optimizing it. Results of the application of these methods to several biological systems including muscle proteins, fibrinogen, ribosomes and chromatin will be discussed.

An electron microscopic study of the intra-myocardial lesions in cases of acute myocardial infarction

1978 ◽  
Vol 36 (2) ◽  
pp. 484-485
Author(s):  
Masahiro Ono ◽  
Kaoru Aihara ◽  
Gompachi Yajima
Keyword(s):  
Myocardial Infarction ◽  
Acute Myocardial Infarction ◽  
Coronary Vessels ◽  
Vascular Wall ◽  
Vascular Changes ◽  
Electron Microscopic ◽  
Main Trunk ◽  
Mechanical Destruction ◽  
Transmission Electron ◽  
Myocardial Lesions

The pathogenesis of the arteriosclerosis in the acute myocardial infarction is the matter of the extensive survey with the transmission electron microscopy in experimental and clinical materials. In the previous communication,the authors have clarified that the two types of the coronary vascular changes could exist. The first category is the case in which we had failed to observe no occlusive changes of the coronary vessels which eventually form the myocardial infarction. The next category is the case in which occlusive -thrombotic changes are observed in which the myocardial infarction will be taken placed as the final event. The authors incline to designate the former category as the non-occlusive-non thrombotic lesions. The most important findings in both cases are the “mechanical destruction of the vascular wall and imbibition of the serous component” which are most frequently observed at the proximal portion of the coronary main trunk.

The Effect of Oxidized Cholesterol on the Aorta of Rabbits- Scanning Electron Microscopic Observations

1982 ◽  
Vol 40 ◽  
pp. 340-341
Author(s):  
S. K. Pena ◽  
C. B. Taylor ◽  
J. Hill ◽  
J. Safarik
Keyword(s):  
Cholesterol Biosynthesis ◽  
Cholesterol Content ◽  
Arterial Injury ◽  
Electron Microscopic ◽  
Aortic Smooth Muscle ◽  
Oxidized Cholesterol ◽  
Initial Event ◽  
Membrane Structure And Function ◽  
Scanning Electron Microscopic ◽  
And Function

Introduction: Oxidized cholesterol derivatives have been demonstrated in various cell cultures to be very potent inhibitors of 3-hvdroxy-3- methylglutaryl Coenzyme A reductase which is a principle regulator of cholesterol biosynthesis in the cell. The cholesterol content in the cells exposed to oxidized cholesterol was found to be markedly decreased. In aortic smooth muscle cells, the potency of this effect was closely related to the cytotoxicity of each derivative. Furthermore, due to the similarity of their molecular structure to that of cholesterol, these oxidized cholesterol derivatives might insert themselves into the cell membrane, alter membrane structure and function and eventually cause cell death. Arterial injury has been shown to be the initial event of atherosclerosis.

A Comparative Study of Fractographic Replicas

1974 ◽  
Vol 32 ◽  
pp. 566-567
Author(s):  
Loren Anderson ◽  
Pat Pizzo ◽  
Glen Haydon
Keyword(s):  
Electron Microscopy ◽  
Electron Microscopic Examination ◽  
Direct Examination ◽  
Electron Microscopic ◽  
Reliable Technique ◽  
Service Failures ◽  
Transmission Electron ◽  
Mode Of Failure ◽  
Scanning Electron Microscopic ◽  
Scanning Electron

Transmission electron microscopy of replicas has long been used to study the fracture surfaces of components which fail in service. Recently, the scanning electron microscope (SEM) has gained popularity because it allows direct examination of the fracture surface. However, the somewhat lower resolution of the SEM coupled with a restriction on the sample size has served to limit the use of this instrument in investigating in-service failures. It is the intent of this paper to show that scanning electron microscopic examination of conventional negative replicas can be a convenient and reliable technique for determining mode of failure.

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