Intercellular spaces in quick-frozen whole hearts of the frog and mouse

1986 ◽  
Vol 44 ◽  
pp. 262-263
Author(s):  
Sommer ◽  
N.R. Wallace ◽  
R. Nassar
Keyword(s):  
Electron Microscopy ◽  
Comparative Study ◽  
Freeze Fracture ◽  
High Fidelity ◽  
Ventricular Muscle ◽  
Intercellular Spaces ◽  
Cardiac Muscle Cells ◽  
Profound Influence ◽  
Quick Freezing

The geometry of cell apposition has a profound influence on certain electrophysiologic properties of aggregates of cardiac muscle cells, e.g. in bundles of frog versus mouse ventricular muscle. It should be assessed, ideally, in the absence of preparatory procedures that can be expected to change it. Since quick-freezing followed by freeze fracture eliminates all but freezing from the preparatory menue prior to electron microscopy, we have applied this technology to a comparative study of the geometry of intercellular spaces in frog and mouse hearts in an attempt to reproduce its in vivo state with high fidelity.

Cationic Liposome-DNA Complexes: Polymorphism versus Transfection Activity

2000 ◽  
Vol 6 (S2) ◽  
pp. 854-855
Author(s):  
B. Sternberg-Papahadjopoulos ◽  
K. Hong ◽  
W. Zheng ◽  
D. Papahadjopoulos
Keyword(s):  
Electron Microscopy ◽  
Cultured Cells ◽  
Freeze Fracture ◽  
Cationic Liposome ◽  
Specific Structure ◽  
Spherical Particles ◽  
Cubic Phase ◽  
Active Structure

Complexes formed during interaction of cationic liposomes with polynucleotides such as DNA (CLDC) self-assemble into a variety of polymorphic structures. They display bilayer (FIG. 1-5) and non-bilayer structures (FIG. 6). We have recorded bilayer structures such as spaghetti/meatball-type structures (FIG. I), map-pins (FIG. 2) spherical particles and invaginated liposomes (FIG. 3, 4) and oligolamellar structures (FIG. 5). The non-bilayer lipid arrangements include honeycombtype structure (Hn, FIG. 6) and cubic phase lipids.We have chosen mainly freeze-fracture electron microscopy (FIG. 1-3, 5,6) but also cryo-electron microscopy (FIG.4) for recording polymorphic structures, and for studying factors and conditions triggering the formation and stabilization of specific structure types. Furthermore, we took microscopically snapshots of the interaction of specific structure types with cultured cells. In order to find out the “active” structure in terms of transfection, we investigated the transfection activity both in vivo and in vitro of CLDC, and studied in parallel their morphology in serum as well as in cell medium.

scholarly journals Mitochondrial morphology, topology, and membrane interactions in skeletal muscle: a quantitative three-dimensional electron microscopy study

2013 ◽  
Vol 114 (2) ◽  
pp. 161-171 ◽  
Author(s):  
Martin Picard ◽  
Kathryn White ◽  
Douglass M. Turnbull
Keyword(s):  
Electron Microscopy ◽  
Skeletal Muscle ◽  
Mitochondrial Membrane ◽  
Freeze Fracture ◽  
Membrane Dynamics ◽  
Mitochondrial Morphology ◽  
Mitochondrial Membranes ◽  
Intact Mouse ◽  
Mouse Skeletal Muscle

Dynamic remodeling of mitochondrial morphology through membrane dynamics are linked to changes in mitochondrial and cellular function. Although mitochondrial membrane fusion/fission events are frequent in cell culture models, whether mitochondrial membranes dynamically interact in postmitotic muscle fibers in vivo remains unclear. Furthermore, a quantitative assessment of mitochondrial morphology in intact muscle is lacking. Here, using electron microscopy (EM), we provide evidence of interacting membranes from adjacent mitochondria in intact mouse skeletal muscle. Electron-dense mitochondrial contact sites consistent with events of outer mitochondrial membrane tethering are also described. These data suggest that mitochondrial membranes interact in vivo among mitochondria, possibly to induce morphology transitions, for kiss-and-run behavior, or other processes involving contact between mitochondrial membranes. Furthermore, a combination of freeze-fracture scanning EM and transmission EM in orthogonal planes was used to characterize and quantify mitochondrial morphology. Two subpopulations of mitochondria were studied: subsarcolemmal (SS) and intermyofibrillar (IMF), which exhibited significant differences in morphological descriptors, including form factor (means ± SD for SS: 1.41 ± 0.45 vs. IMF: 2.89 ± 1.76, P < 0.01) and aspect ratio (1.97 ± 0.83 vs. 3.63 ± 2.13, P < 0.01) and circularity (0.75 ± 0.16 vs. 0.45 ± 0.22, P < 0.01) but not size (0.28 ± 0.31 vs. 0.27 ± 0.20 μm2). Frequency distributions for mitochondrial size and morphological parameters were highly skewed, suggesting the presence of mechanisms to influence mitochondrial size and shape. In addition, physical continuities between SS and IMF mitochondria indicated mixing of both subpopulations. These data provide evidence that mitochondrial membranes interact in vivo in mouse skeletal muscle and that factors may be involved in regulating skeletal muscle mitochondrial morphology.

scholarly journals Organization of acetylcholine receptors in quick-frozen, deep-etched, and rotary-replicated Torpedo postsynaptic membrane.

1979 ◽  
Vol 82 (1) ◽  
pp. 150-173 ◽  
Author(s):  
J E Heuser ◽  
S R Salpeter
Keyword(s):  
Acetylcholine Receptors ◽  
Membrane Surface ◽  
Freeze Fracture ◽  
Electric Organ ◽  
Postsynaptic Membrane ◽  
Deep Etching ◽  
Geometrical Pattern ◽  
Quick Freezing ◽  
Surface Patterns

The receptor-rich postsynaptic membrane of the elasmobranch electric organ was fixed by quick-freezing and then viewed by freeze-fracture, deep-etching and rotary-replication. Traditional freeze-fracture revealed a distinct, geometrical pattern of shallow 8.5-nm bumps on the E fracture-face, similar to the lattice which has been seen before in chemically fixed material, but seen less clearly than after quick-freezing. Fracture plus deep-etching brought into view on the true outside of this membrane a similar geometrical pattern of 8.5-nm projections rising out of the membrane surface. The individual projections looked like structures that have been seen in negatively stained or deep-etched membrane fragments and have been identified as individual acetylcholine receptor molecules. The surface protrusions were twice as abundant as the large intramembrane particles that characterize the fracture faces of this membrane, which have also been considered to be receptor molecules. Particle counts have always been too low to match the estimates of postsynaptic receptor density derived from physiological and biochemical studies; counts of surface projections, however, more closely matched these estimates. Rotary-replication of quick-frozen, etched postsynaptic membranes enhanced the visibility of these surface protuberances and illustrated that they often occur in dimers, tetramers, and ordered rows. The variations in these surface patterns suggested that in vivo, receptors in the postsynaptic membrane may tend to pack into "liquid crystals" which constantly appear, flow, and disappear in the fluid environment of the membrane. Additionally, deep-etching revealed a distinct web of cytoplasmic filaments beneath the postsynaptic membrane, and revealed the basal lamina above it; and delineated possible points of contact between these structures and the membrane proper.

A Langendorf preparation for quick-freezing small hearts

1992 ◽  
Vol 50 (1) ◽  
pp. 774-775
Author(s):  
Joachim Sommer ◽  
Teresa High ◽  
Peter Ingram ◽  
Rashid Nassar ◽  
Neal Shepherd
Keyword(s):  
Membrane Damage ◽  
Freeze Fracture ◽  
Freeze Substitution ◽  
Tissue Preparation ◽  
Cell Structures ◽  
Freeze Dried ◽  
Quick Freezing ◽  
Cardiac Ultrastructure

The validity of studies of cell structures at high spatial and temporal resolution depends on the fidelity with which tissue preparation maintains in vivo conditions. Optimal preservation of structural substrates of precisely timed physiological intracellular events is offered by cryopreservation followed by freeze-fracture and freeze-substitution; we have established criteria for gauging that quality of cryopreservation in skeletal and cardiac muscle. Ciyopreservation is indispensable for electron probe x-ray microanalysis (EPXMA) of freeze-dried cryosections. We have developed a Langendorf preparation for small hearts (Figs. 1,2) suitable for use in our quick-freeze device (“Cryopress”; Med-Vac, Inc., St. Louis, MO 63117) to a) investigate the spatial distribution of physiologically important elements (e.g. calcium) during excitation-contraction coupling (ECC), especially in intact avian hearts and, b) assess damage to cardiac ultrastructure that is caused by pathological conditions (e.g. ischemia), rather than by artifacts due to chemical fixation (e.g. membrane damage by glutaraldehyde). In our Langendorf preparation, the tips of hearts can be quick-frozen at optimal freezing conditions, and comparative studies of the hearts of different animal species performed.

scholarly journals Monitoring Candida parapsilosis and Staphylococcus epidermidis Biofilms by a Combination of Scanning Electron Microscopy and Raman Spectroscopy

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4089 ◽  
Author(s):  
Kamila Hrubanova ◽  
Vladislav Krzyzanek ◽  
Jana Nebesarova ◽  
Filip Ruzicka ◽  
Zdenek Pilat ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Chemical Composition ◽  
Sample Preparation ◽  
Staphylococcus Epidermidis ◽  
Candida Parapsilosis ◽  
Freeze Fracture ◽  
Biofilm Structure ◽  
Scanning Electron

The biofilm-forming microbial species Candida parapsilosis and Staphylococcus epidermidis have been recently linked to serious infections associated with implanted medical devices. We studied microbial biofilms by high resolution scanning electron microscopy (SEM), which allowed us to visualize the biofilm structure, including the distribution of cells inside the extracellular matrix and the areas of surface adhesion. We compared classical SEM (chemically fixed samples) with cryogenic SEM, which employs physical sample preparation based on plunging the sample into various liquid cryogens, as well as high-pressure freezing (HPF). For imaging the biofilm interior, we applied the freeze-fracture technique. In this study, we show that the different means of sample preparation have a fundamental influence on the observed biofilm structure. We complemented the SEM observations with Raman spectroscopic analysis, which allowed us to assess the time-dependent chemical composition changes of the biofilm in vivo. We identified the individual spectral peaks of the biomolecules present in the biofilm and we employed principal component analysis (PCA) to follow the temporal development of the chemical composition.

Effect of ADH on Rat Renal Papilla, an Ultrastructural and Cytochemical Study

1973 ◽  
Vol 31 ◽  
pp. 410-411
Author(s):  
C. N. Sun ◽  
H. J. White ◽  
E. J. Towbin
Keyword(s):  
Electron Microscopy ◽  
Diabetes Insipidus ◽  
Renal Papilla ◽  
Milk Diet ◽  
Intercellular Spaces ◽  
Cytochemical Study ◽  
Collecting Tubule ◽  
Concentrate Urine ◽  
Staining Techniques ◽  
Collecting Tubules

Diabetes insipidus and compulsive water drinking are representative of two categories of antidiuretic hormone (ADH) lack. We studied a strain of rats with congenital diabetes insipidus homozygote (DI) and normal rats on an isocaloric fortified dilute milk diet. In both cases, the collecting tubules could not concentrate urine. Special staining techniques, Alcian Blue-PAS for light microscopy and lanthanum nitrate for electron microscopy were used to demonstrate the changes in interstitial mucopolysaccharides (MPS). The lanthanum staining was done according to the method of Khan and Overton.Electron microscopy shows cytoplasmic lesions, vacules, swelling and degenerating mitochondria and intercellular spaces (IS) in the collecting tubule cells in DI and rats on milk diet.

The Infection of Cells by Bullet-Shaped Viruses

1969 ◽  
Vol 27 ◽  
pp. 372-373
Author(s):  
Frederick A. Murphy ◽  
Alyne K. Harrison ◽  
Sylvia G. Whitfield
Keyword(s):  
Electron Microscopy ◽  
Physical Properties ◽  
Host Cell ◽  
Thin Section ◽  
Cultured Cells ◽  
Cell Infection ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Section Electron Microscopy

The bullet-shaped viruses are currently classified together on the basis of similarities in virion morphology and physical properties. Biologically and ecologically the member viruses are extremely diverse. In searching for further bases for making comparisons of these agents, the nature of host cell infection, both in vivo and in cultured cells, has been explored by thin-section electron microscopy.

Ultrastructure of melanocyte-keratinocyte interactions and pigment transfer in vitro

1978 ◽  
Vol 36 (2) ◽  
pp. 650-651
Author(s):  
Raul I. Garcia ◽  
Evelyn A. Flynn ◽  
George Szabo
Keyword(s):  
Direct Injection ◽  
Skin Pigmentation ◽  
Freeze Fracture ◽  
Pigment Granule ◽  
Time Lapse ◽  
Ultrastructural Level ◽  
Lanthanum Tracer ◽  
A Cell

Skin pigmentation in mammals involves the interaction of epidermal melanocytes and keratinocytes in the structural and functional unit known as the Epidermal Melanin Unit. Melanocytes(M) synthesize melanin within specialized membrane-bound organelles, the melanosome or pigment granule. These are subsequently transferred by way of M dendrites to keratinocytes(K) by a mechanism still to be clearly defined. Three different, though not necessarily mutually exclusive, mechanisms of melanosome transfer have been proposed: cytophagocytosis by K of M dendrite tips containing melanosomes, direct injection of melanosomes into the K cytoplasm through a cell-to-cell pore or communicating channel formed by localized fusion of M and K cell membranes, release of melanosomes into the extracellular space(ECS) by exocytosis followed by K uptake using conventional phagocytosis. Variability in methods of transfer has been noted both in vivo and in vitro and there is evidence in support of each transfer mechanism. We Have previously studied M-K interactions in vitro using time-lapse cinemicrography and in vivo at the ultrastructural level using lanthanum tracer and freeze-fracture.

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