Freeze-etching study on membrane ultrastructural changes caused by freezing: Cooling rate-dependent intramembrane particle aggregation in erythrocyte stripped ghosts

Cryobiology ◽  
1985 ◽  
Vol 22 (1) ◽  
pp. 69-76 ◽  
Author(s):  
Seizo Fujikawa
Keyword(s):  
Cooling Rate ◽  
Particle Aggregation ◽  
Ultrastructural Changes ◽  
Intramembrane Particle ◽  
Rate Dependent ◽  
Freeze Etching

scholarly journals INTRAMEMBRANE PARTICLE AGGREGATION IN ERYTHROCYTE GHOSTS

1974 ◽  
Vol 63 (3) ◽  
pp. 1018-1030 ◽  
Author(s):  
Arnljot Elgsaeter ◽  
Daniel Branton
Keyword(s):  
Membrane Protein ◽  
Erythrocyte Membrane ◽  
Human Erythrocyte ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Particle Aggregation ◽  
Erythrocyte Ghosts ◽  
Intramembrane Particle ◽  
Freeze Etching ◽  
Human Erythrocyte Ghost

We have used freeze-etching and SDS-polyacrylamide gel electrophoresis to study the conditions under which the intramembrane particles of the human erythrocyte ghost may be aggregated. The fibrous membrane protein, spectrin, can be almost entirely removed from erythrocyte ghosts with little or no change in the distribution of the particles. However, after spectrin depletion, particle aggregation in the plane of the membrane may be induced by conditions which cause little aggregation in freshly prepared ghosts. This suggests that the spectrin molecules form a molecular meshwork which limits the translational mobility of the erythrocyte membrane particles.

Evaluation of Freezing Methods by Low Temperature X-Ray Diffraction

1977 ◽  
Vol 35 ◽  
pp. 330-333
Author(s):  
T. Gulik-Krzywicki ◽  
M.J. Costello
Keyword(s):  
Biological Materials ◽  
Molecular Organization ◽  
X Ray Diffraction ◽  
Glass Capillary ◽  
X Ray ◽  
Rate Dependent ◽  
Before And After ◽  
Freeze Etching ◽  
Diffraction Patterns ◽  
Set Up

Freeze-etching electron microscopy is currently one of the best methods for studying molecular organization of biological materials. Its application, however, is still limited by our imprecise knowledge about the perturbations of the original organization which may occur during quenching and fracturing of the samples and during the replication of fractured surfaces. Although it is well known that the preservation of the molecular organization of biological materials is critically dependent on the rate of freezing of the samples, little information is presently available concerning the nature and the extent of freezing-rate dependent perturbations of the original organizations. In order to obtain this information, we have developed a method based on the comparison of x-ray diffraction patterns of samples before and after freezing, prior to fracturing and replication.Our experimental set-up is shown in Fig. 1. The sample to be quenched is placed on its holder which is then mounted on a small metal holder (O) fixed on a glass capillary (p), whose position is controlled by a micromanipulator.

Cooling rate dependent undercooling of Bi in a Zn matrix by differential fast scanning calorimetry

2014 ◽  
Vol 30 (2) ◽  
pp. 242-247 ◽  
Author(s):  
Linfang Li ◽  
Bingge Zhao ◽  
Bin Yang ◽  
Quanliang Zhang ◽  
Qijie Zhai ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Scanning Calorimetry ◽  
Rate Dependent ◽  
Fast Scanning Calorimetry ◽  
Image Position

Abstract

The effect of various cooling rates on the membrane ultrastructure of frozen human erythrocytes and its relation to the extent of haemolysis after thawing

1981 ◽  
Vol 49 (1) ◽  
pp. 369-382
Author(s):  
S. Fujikawa
Keyword(s):  
Cooling Rate ◽  
Human Erythrocytes ◽  
Ice Crystals ◽  
Erythrocyte Membranes ◽  
Ultrastructural Changes ◽  
Cooling Rates ◽  
Intracellular Ice ◽  
Frozen State ◽  
Membrane Ultrastructure ◽  
Fast Freezing

Human erythrocytes suspended in buffered isotonic saline were frozen to the temperature of liquid nitrogen at various cooling rates of 3, 140, 700, 1800, 3500, 8000 and 11 500 deg. C/min. The membrane ultrastructure in the frozen state and the extent of haemolysis after thawing were examined at each cooling rate. As the cooling rates increased from 3 to 3500 deg. C/min, the extent of lysis gradually decreased, but further increase in cooling rates in excess of 8000 deg. C/min resulted in an abrupt increase of lysis. Membrane-associated vesicles devoid of intramembrane particles (IMPs) were formed in the erythrocyte membranes frozen at cooling rates slower than 1800 deg. C/min. The frequency and size of these vesicles were highly cooling-rate-dependent and they were no longer formed in the erythrocyte membranes frozen at cooling rates faster than 3500 deg. C/min. Another membrane ultrastructural change associated closely with the formation of intracellular ice crystals appeared at cooling rates faster than 8000 deg. C/min. The membrane regions in direct contact with intracellular ice crystals were physically damaged and had an appearance resembling worm-eaten spots. The erythrocytes frozen at a cooling rate of 3500 deg. C/min exhibited ultrastructural integrity of the membrane by avoiding the membrane changes caused by either slow or fast freezing. It is suggested, from the close relation between membrane ultrastructure and the extent of haemolysis, that the ultrastructural integrity of membrane in the frozen state is important for avoiding haemolysis after thawing, and that the membrane ultrastructural changes caused by both slow and fast freezing were responsible for the lysis after thawing.

scholarly journals Analysis of isothermal and cooling rate dependent immersion freezing by a unifying stochastic ice nucleation model

2015 ◽  
Vol 15 (9) ◽  
pp. 13109-13166
Author(s):  
P. A. Alpert ◽  
D. A. Knopf
Keyword(s):  
Cooling Rate ◽  
Surface Area ◽  
Ice Nucleation ◽  
Rate Dependence ◽  
Nucleation Theory ◽  
Freezing Process ◽  
Nucleation Kinetics ◽  
Rate Dependent ◽  
Immersion Freezing ◽  
The Impact

Abstract. Immersion freezing is an important ice nucleation pathway involved in the formation of cirrus and mixed-phase clouds. Laboratory immersion freezing experiments are necessary to determine the range in temperature (T) and relative humidity (RH) at which ice nucleation occurs and to quantify the associated nucleation kinetics. Typically, isothermal (applying a constant temperature) and cooling rate dependent immersion freezing experiments are conducted. In these experiments it is usually assumed that the droplets containing ice nuclei (IN) all have the same IN surface area (ISA), however the validity of this assumption or the impact it may have on analysis and interpretation of the experimental data is rarely questioned. A stochastic immersion freezing model based on first principles of statistics is presented, which accounts for variable ISA per droplet and uses physically observable parameters including the total number of droplets (Ntot) and the heterogeneous ice nucleation rate coefficient, Jhet(T). This model is applied to address if (i) a time and ISA dependent stochastic immersion freezing process can explain laboratory immersion freezing data for different experimental methods and (ii) the assumption that all droplets contain identical ISA is a valid conjecture with subsequent consequences for analysis and interpretation of immersion freezing. The simple stochastic model can reproduce the observed time and surface area dependence in immersion freezing experiments for a variety of methods such as: droplets on a cold-stage exposed to air or surrounded by an oil matrix, wind and acoustically levitated droplets, droplets in a continuous flow diffusion chamber (CFDC), the Leipzig aerosol cloud interaction simulator (LACIS), and the aerosol interaction and dynamics in the atmosphere (AIDA) cloud chamber. Observed time dependent isothermal frozen fractions exhibiting non-exponential behavior with time can be readily explained by this model considering varying ISA. An apparent cooling rate dependence ofJhet is explained by assuming identical ISA in each droplet. When accounting for ISA variability, the cooling rate dependence of ice nucleation kinetics vanishes as expected from classical nucleation theory. The model simulations allow for a quantitative experimental uncertainty analysis for parameters Ntot, T, RH, and the ISA variability. In an idealized cloud parcel model applying variability in ISAs for each droplet, the model predicts enhanced immersion freezing temperatures and greater ice crystal production compared to a case when ISAs are uniform in each droplet. The implications of our results for experimental analysis and interpretation of the immersion freezing process are discussed.

Fine structure of the kidneys of osmotically stressed Mytilus, Mercenari, and Anodonta

1986 ◽  
Vol 64 (12) ◽  
pp. 2779-2787 ◽  
Author(s):  
Hamidur R. Khan ◽  
Mary Lou Ashton ◽  
A. S. M. Saleuddin
Keyword(s):  
Basal Membrane ◽  
Ultrastructural Changes ◽  
Freshwater Bivalve ◽  
Septate Junctions ◽  
Intramembrane Particle ◽  
Marine Bivalves ◽  
Fluorescent Stain ◽  
Cytoskeletal Elements ◽  
Lateral Cell ◽  
Membrane Infoldings

Osmotically induced ultrastructural changes in the kidneys of the freshwater bivalve Anodonta and the marine bivalves Mytilus and Mercenaria were studied. Osmotic stresses were given to Anodonta by keeping them in distilled water or in 6% seawater, and to Mytilus and Mercenaria by keeping them in 50% seawater for various periods. In all of these bivalves, the convoluted, single cell layered kidney epithelia displayed wide lateral intercellular spaces as well as extracellular spaces in the basal membrane infoldings during hyposmotic stress. These spaces were greatly reduced when the animals were kept in isosmotic media (i.e., isosmotic to their respective hemolymphs). The kidney cells contained abundant cytoskeletal elements and microfilaments were often observed in bundles in the basal membrane infoldings. Actin was observed in the basal membrane infoldings using the specific fluorescent stain nitrobenzoxadiazole-phallacidin. The cell contacts of the kidney epthelia were studied in platinum replicas of freeze-fractured tissues. The lateral cell membrane and basal membrane infoldings contained many gap junctions. Many rows of dense intramembrane particles of septate junctions were observed in the kidneys of animals from isosmotic media. The septate junctions in the kidneys of aminals from hyposmotic media contained either fewer intramembrane particle rows or many sinuous intramembrane particle rows. The site of prourine formation in mollusks are discussed.

Microstructure Characterization of Ni-V Splat Quenched Foils

1997 ◽  
Vol 3 (S2) ◽  
pp. 694-695
Author(s):  
H. Sieber ◽  
D.R. Allen ◽  
J. Perepezko
Keyword(s):  
Cooling Rate ◽  
Cross Section ◽  
Phase 1 ◽  
Nucleation And Growth ◽  
Growth Behavior ◽  
Plan View ◽  
Σ Phase ◽  
Rate Dependent ◽  
Section Sample

Although the thickness of splat quenched (SQ) foils is normally less then 100 μm the solidified microstructure is usually not homogenous, but rather is determined by a cooling rate dependent nucleation and growth behavior of the different phases. The cooling rate and thus the microstructure changes significantly with distance from the edge to the middle of the SQ foils. Rapidly quenched nickel-vanadium (Ni-V) foils consist of three phases formed during solidification, a Ni-fcc, a V-bcc and a intermetallic σ phase [1-3]. To interpret the microstructure evolution in detail, a special TEM cross section sample preparation was applied. The SQ foil was ground to 30 μm, glued on a copper grid and ion-milled parallel to the foils (Fig.1a). In Ni-49V SQ foils seven typical microstructure regions (see Fig. 1 b) could be identified and were analyzed in detail by TEM investigations in plan view and cross section geometries. Furthermore, three solidification pathways were identified.

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