Representation in Biological Systems: Teleofunction, Etiology, and Structural Preservation

2012 ◽  
pp. 161-185 ◽  
Author(s):  
Michael Nair-Collins
Keyword(s):  
Biological Systems ◽  
Structural Preservation

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.

Structural preservation and absolute contrast of catalase crystal sections prepared with tannic acid

1983 ◽  
Vol 41 ◽  
pp. 448-449
Author(s):  
C.W. Akey ◽  
M. Szalay ◽  
S.J. Edelstein
Keyword(s):  
Tannic Acid ◽  
Beef Heart ◽  
X Rays ◽  
Screw Axis ◽  
General Applicability ◽  
Thin Sections ◽  
Beef Liver ◽  
3 Dimensional ◽  
Dimensional Reconstruction ◽  
Structural Preservation

Three methods of obtaining 20 Å resolution in sectioned protein crystals have recently been described. They include tannic acid fixation, low temperature embedding and grid sectioning. To be useful for 3-dimensional reconstruction thin sections must possess suitable resolution, structural fidelity and a known contrast. Tannic acid fixation appears to satisfy the above criteria based on studies of crystals of Pseudomonas cytochrome oxidase, orthorhombic beef liver catalase and beef heart F1-ATPase. In order to develop methods with general applicability, we have concentrated our efforts on a trigonal modification of catalase which routinely demonstrated a resolution of 40 Å. The catalase system is particularly useful since a comparison with the structure recently solved with x-rays will permit evaluation of the accuracy of 3-D reconstructions of sectioned crystals.Initially, we re-evaluated the packing of trigonal catalase crystals studied by Longley. Images of the (001) plane are of particular interest since they give a projection down the 31-screw axis in space group P3121. Images obtained by the method of Longley or by tannic acid fixation are negatively contrasted since control experiments with orthorhombic catalase plates yield negatively stained specimens with conditions used for the larger trigonal crystals.

High-Resolution Scanning Electron Microscopy of Biological Specimens

1988 ◽  
Vol 46 ◽  
pp. 186-187
Author(s):  
M. Müller ◽  
R. Hermann
Keyword(s):  
High Resolution ◽  
Freeze Drying ◽  
Room Temperature ◽  
Structural Information ◽  
Freeze Substitution ◽  
Critical Point Drying ◽  
Sem Study ◽  
Major Factors ◽  
Structural Preservation ◽  
Preparation Techniques

Three major factors must be concomitantly assessed in order to extract relevant structural information from the surface of biological material at high resolution (2-3nm).Procedures based on chemical fixation and dehydration in graded solvent series seem inappropriate when aiming for TEM-like resolution. Cells inevitably shrink up to 30-70% of their initial volume during gehydration; important surface components e.g. glycoproteins may be lost. These problems may be circumvented by preparation techniques based on cryofixation. Freezedrying and freeze-substitution followed by critical point drying yields improved structural preservation in TEM. An appropriate preservation of dimensional integrity may be achieved by freeze-drying at - 85° C. The sample shrinks and may partially collapse as it is warmed to room temperature for subsequent SEM study. Observations at low temperatures are therefore a necessary prerequisite for high fidelity SEM. Compromises however have been unavoidable up until now. Aldehyde prefixation is frequently needed prior to freeze drying, rendering the sample resistant to treatment with distilled water.

A comparison of three cryotechniques (freeze-drying, cryosubstitution, cryosectioning) of specimen preparation for immunolabelling of bacterial antigens of Coxiella burnetii

1994 ◽  
Vol 52 ◽  
pp. 140-141
Author(s):  
T. F. McCaul ◽  
R. J. Gould
Keyword(s):  
Coxiella Burnetii ◽  
Freeze Drying ◽  
Stress Proteins ◽  
Cultured Cells ◽  
High Specificity ◽  
Specimen Preparation ◽  
Bacterial Antigens ◽  
Structural Preservation ◽  
Nuclear Ribonucleoprotein ◽  
Cellular Components

Immuno-electron microscopy has allowed the selective localisation of molecules with high resolution and high specificity. Cryopreparatory methods have provided better retention of antigenicity suitable for precise immunolabelling together with optimal structural preservation of cellular components. Cryosubstitution and cryoultramicrotomy have widely been exploited for immunolabelling. Molecular Distillation Dryer (MDD), a form of freeze-drying technique, has recently been used for immunolabelling of Plasmodium falciparum stress proteins and nuclear ribonucleoprotein particles in cultured cells. In the present study, we report the comparison of all three cryotechniques in the immunolabelling of bacterial antigens of Coxiella burnetii.The highly infectious C. burnetii was prefixed in 3% glutaraldehyde (66 mM cacodylate buffer, pH 6.8 ). The cells were then pre-embedded in 2% low-temperature agarose on Durapore hydrophilic membrane prior to cryofixation using a LifeCell CF100 metal-mirror system. A 1% glutaraldehyde in 100% methanol was used as a medium for cryosubstitution in a Reichert CS Auto Cryosubstitution apparatus.

Freeze-substitution of rye grass and ragweed pollen grains

1990 ◽  
Vol 48 (3) ◽  
pp. 686-687
Author(s):  
Liza B. Martinez ◽  
Susan M. Wick
Keyword(s):  
Cell Function ◽  
Pollen Grains ◽  
Freeze Substitution ◽  
Cell Types ◽  
Rapid Freezing ◽  
Rye Grass ◽  
Acrylic Resins ◽  
Allergenic Proteins ◽  
Cold Embedding ◽  
Structural Preservation

Rapid freezing and freeze-substitution have been employed as alternatives to chemical fixation because of the improved structural preservation obtained in various cell types. This has been attributed to biomolecular immobilization derived from the extremely rapid arrest of cell function. These methods allow the elimination of conventionally used fixatives, which may have denaturing or “masking” effects on proteins. Thus, this makes them ideal techniques for immunocytochemistry, in which preservation of both ultrastructure and antigenicity are important. These procedures are also compatible with cold embedding acrylic resins which are known to increase sensitivity in immunolabelling.This study reveals how rapid freezing and freeze-substitution may prove to be useful in the study of the mobile allergenic proteins of rye grass and ragweed. Most studies have relied on the use of osmium tetroxide to achieve the necessary ultrastructural detail in pollen whereas those that omitted it have had to contend with poor overall preservation.

Freeze-fracture cytochemistry: A goal set by Russell Steere in 1957

1993 ◽  
Vol 51 ◽  
pp. 60-61
Author(s):  
Nicholas J Severs
Keyword(s):  
Chemical Nature ◽  
Biological Systems ◽  
Freeze Fracture ◽  
Structural Components ◽  
Major Goal ◽  
Membrane Biology ◽  
Routine Application ◽  
The Future ◽  
Freeze Etching

In his pioneering demonstration of the potential of freeze-etching in biological systems, Russell Steere assessed the future promise and limitations of the technique with remarkable foresight. Item 2 in his list of inherent difficulties as they then stood stated “The chemical nature of the objects seen in the replica cannot be determined”. This defined a major goal for practitioners of freeze-fracture which, for more than a decade, seemed unattainable. It was not until the introduction of the label-fracture-etch technique in the early 1970s that the mould was broken, and not until the following decade that the full scope of modern freeze-fracture cytochemistry took shape. The culmination of these developments in the 1990s now equips the researcher with a set of effective techniques for routine application in cell and membrane biology.Freeze-fracture cytochemical techniques are all designed to provide information on the chemical nature of structural components revealed by freeze-fracture, but differ in how this is achieved, in precisely what type of information is obtained, and in which types of specimen can be studied.

Seeking to uncover biology's chemical roots

2019 ◽  
Vol 3 (5) ◽  
pp. 435-443 ◽  
Author(s):  
Addy Pross
Keyword(s):  
Environmental Changes ◽  
Biological Systems ◽  
Significant Development ◽  
The Road ◽  
Physical Chemical ◽  
Systems Chemistry ◽  
Biological World ◽  
Inanimate Matter ◽  
The Origin Of Life ◽  
Opening Up

Despite the considerable advances in molecular biology over the past several decades, the nature of the physical–chemical process by which inanimate matter become transformed into simplest life remains elusive. In this review, we describe recent advances in a relatively new area of chemistry, systems chemistry, which attempts to uncover the physical–chemical principles underlying that remarkable transformation. A significant development has been the discovery that within the space of chemical potentiality there exists a largely unexplored kinetic domain which could be termed dynamic kinetic chemistry. Our analysis suggests that all biological systems and associated sub-systems belong to this distinct domain, thereby facilitating the placement of biological systems within a coherent physical/chemical framework. That discovery offers new insights into the origin of life process, as well as opening the door toward the preparation of active materials able to self-heal, adapt to environmental changes, even communicate, mimicking what transpires routinely in the biological world. The road to simplest proto-life appears to be opening up.

DEFECTS AND TEXTURES IN CHOLESTERIC ANALOGUES GIVEN BY SOME BIOLOGICAL SYSTEMS

1975 ◽  
Vol 36 (C1) ◽  
pp. C1-331-C1-336 ◽  
Author(s):  
Y. BOULIGAND
Keyword(s):  
Biological Systems
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