Magnetic Ordering in Ilmenites and Corundum-Ordered Structures

The suggested precursor-product relationship between the nuclear pre-mRNA and the cytoplasmic mRNA has created increased interest also in the structure of these RNA species. Previously we have been published electron micrographs of individual pre-mRNA molecules from erythroid cells. An intersting observation was the appearance of a contour, probably corresponding to higher ordered structures, on one end of 10 % of the pre-mRNA molecules from erythroid rabbit bone marrow cells (Fig. 1A). A virtual similar contour was observed in molecules of 9S globin mRNA from rabbit reticulocytes (Fig. 1B). A structural transformation in a linear contour occurs if the RNA is heated for 10 min to 90°C in the presence of 80 % formamide. This structural transformation is reversible when the denatured RNA is precipitated and redissolved in 0.2 M ammonium acetate.

Download Full-text

Specific Labeling of Protein Domains with Antibody Fragments

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100098587 ◽

1981 ◽

Vol 39 ◽

pp. 416-417

Author(s):

U. Aebi ◽

L.E. Buhle ◽

W.E. Fowler

Keyword(s):

Image Processing ◽

Specific Protein ◽

Antibody Fragments ◽

Supramolecular Organization ◽

Two Dimensional ◽

Ordered Structures ◽

Virus Capsids ◽

Processing Techniques

Many important supramolecular structures such as filaments, microtubules, virus capsids and certain membrane proteins and bacterial cell walls exist as ordered polymers or two-dimensional crystalline arrays in vivo. In several instances it has been possible to induce soluble proteins to form ordered polymers or two-dimensional crystalline arrays in vitro. In both cases a combination of electron microscopy of negatively stained specimens with analog or digital image processing techniques has proven extremely useful for elucidating the molecular and supramolecular organization of the constituent proteins. However from the reconstructed stain exclusion patterns it is often difficult to identify distinct stain excluding regions with specific protein subunits. To this end it has been demonstrated that in some cases this ambiguity can be resolved by a combination of stoichiometric labeling of the ordered structures with subunit-specific antibody fragments (e.g. Fab) and image processing of the electron micrographs recorded from labeled and unlabeled structures.

Download Full-text

EMCAT: An automatic image-processing system for electron-microscopic tomography

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100169821 ◽

1994 ◽

Vol 52 ◽

pp. 418-419

Author(s):

Weiping Liu ◽

John W. Sedat ◽

David A. Agard

Keyword(s):

Image Processing ◽

Structural Information ◽

Imaging Technique ◽

Three Dimensional ◽

Processing System ◽

Electron Microscopic ◽

Data Set ◽

Ordered Structures ◽

Automatic Image Processing ◽

Em Tomography

Any real world object is three-dimensional. The principle of tomography, which reconstructs the 3-D structure of an object from its 2-D projections of different view angles has found application in many disciplines. Electron Microscopic (EM) tomography on non-ordered structures (e.g., subcellular structures in biology and non-crystalline structures in material science) has been exercised sporadically in the last twenty years or so. As vital as is the 3-D structural information and with no existing alternative 3-D imaging technique to compete in its high resolution range, the technique to date remains the kingdom of a brave few. Its tedious tasks have been preventing it from being a routine tool. One keyword in promoting its popularity is automation: The data collection has been automated in our lab, which can routinely yield a data set of over 100 projections in the matter of a few hours. Now the image processing part is also automated. Such automations finish the job easier, faster and better.

Download Full-text