Liver fibrosis alters the molecular structures of hepatic glycogen

The visualization of organic macromolecules such as proteins, nucleic acids, viruses and virus components has reached its high degree of effectiveness owing to refinements and reliability of instruments and to the invention of methods for enhancing the structure of these materials within the electron image. The latter techniques have been most important because what can be seen depends upon the molecular and atomic character of the object as modified which is rarely evident in the pristine material. Structure may thus be displayed by the arts of positive and negative staining, shadow casting, replication and other techniques. Enhancement of contrast, which delineates bounds of isolated macromolecules has been effected progressively over the years as illustrated in Figs. 1, 2, 3 and 4 by these methods. We now look to the future wondering what other visions are waiting to be seen. The instrument designers will need to exact from the arts of fabrication the performance that theory has prescribed as well as methods for phase and interference contrast with explorations of the potentialities of very high and very low voltages. Chemistry must play an increasingly important part in future progress by providing specific stain molecules of high visibility, substrates of vanishing “noise” level and means for preservation of molecular structures that usually exist in a solvated condition.

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Distribution of newly formed hepatic glycogen in adrenalectomized rats as observed by radioautography after injection of 3H-galactose

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100111252 ◽

1984 ◽

Vol 42 ◽

pp. 228-229

Author(s):

J. E. Michaels ◽

J. T. Hung ◽

E. L. Cardell ◽

R. R. Cardell

Keyword(s):

Glycogen Synthesis ◽

Hepatic Glycogen ◽

Electron Microscopic ◽

Routine Procedures ◽

Silver Grains ◽

Synthetic Glucocorticoid ◽

Adrenalectomized Rats

In order to study early events of glycogen synthesis, we have used adrenalectomized (ADX) rats fasted overnight and injected with the synthetic glucocorticoid dexamethasone (DEX) to stimulate glycogen synthesis. Rats were given DEX 0-5 hr prior to sacrifice and injected with 2 mCi 3H-galactose 1 hr prior to sacrifice. Liver was prepared for light (LM) and electron microscopic (EM) radioautography by routine procedures.The concentration of silver grains over hepatic cytoplasm was measured in LM radioautographs using a Zeiss Videoplan. The hepatocytes were categorized as unlabeled if no silver grains (gr) were present, lightly labeled (<10gr/100 μm2 cytoplasm) or intensely labeled (>10 gr/1002 μm cytoplasm). Although very few hepatocytes showed heavy labeling after 1 hr treatment with DEX, by 2 hr after DEX treatment 8% of the cells distributed throughout the lobule were intensely labeled.

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3H-galactose and 3H-glucose incorporation into newly synthesized hepatic glycogen in control-fed rats

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100143080 ◽

1986 ◽

Vol 44 ◽

pp. 292-293

Author(s):

J.E. Michaels ◽

S.A. Garfield ◽

J.T. Hung ◽

S.S. Smith ◽

R.R. Cardell

Keyword(s):

Biochemical Analysis ◽

Glycogen Synthesis ◽

Hepatic Glycogen ◽

Electron Microscopic ◽

Once Daily ◽

Tail Vein ◽

Tracer Dose ◽

Glucose Incorporation ◽

Wet Weight

3H-galactose (gal) and 3H-glucose (glu) were compared to determine which compound was preferable for pulse labeling newly formed hepatic glycogen. Control fed rats were used to achieve substantial and consistent levels of hepatic glycogen and to stimulate glycogen synthesis.Rats fed once daily for 4 hr achieved hepatic glycogen levels > 3% wet weight liver prior to injection by tail vein of a tracer dose of 3H-gal or 3H-glu. The rats were sacrificed 15-120 min later and liver was prepared by routine techniques for light (LM) and electron microscopic (EM) radioautography (RAG) and biochemical analysis.

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Scanning tunneling microscopy (STM) of DNA and RNA

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100152148 ◽

1989 ◽

Vol 47 ◽

pp. 34-35

Author(s):

Patricia G. Arscott ◽

Gil Lee ◽

Victor A. Bloomfield ◽

D. Fennell Evans

Keyword(s):

Molecular Structures ◽

Inorganic Materials ◽

Resolving Power ◽

Scanning Tunneling ◽

Tunneling Microscopy ◽

Form And Function ◽

Dna And Rna ◽

Calf Thymus ◽

And Function ◽

The Relationship

STM is one of the most promising techniques available for visualizing the fine details of biomolecular structure. It has been used to map the surface topography of inorganic materials in atomic dimensions, and thus has the resolving power not only to determine the conformation of small molecules but to distinguish site-specific features within a molecule. That level of detail is of critical importance in understanding the relationship between form and function in biological systems. The size, shape, and accessibility of molecular structures can be determined much more accurately by STM than by electron microscopy since no staining, shadowing or labeling with heavy metals is required, and there is no exposure to damaging radiation by electrons. Crystallography and most other physical techniques do not give information about individual molecules.We have obtained striking images of DNA and RNA, using calf thymus DNA and two synthetic polynucleotides, poly(dG-me5dC)·poly(dG-me5dC) and poly(rA)·poly(rU).

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Molecular architecture and functions of the neuronal cytoskeleton

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100157541 ◽

1990 ◽

Vol 48 (3) ◽

pp. 2-3

Author(s):

Nobutaka Hirokawa

Keyword(s):

Major Elements ◽

Molecular Structures ◽

Organelle Transport ◽

Molecular Architecture ◽

Neuronal Morphogenesis ◽

Microtubule Associated Proteins ◽

Associated Proteins ◽

And Function ◽

Small Clusters

In this symposium I will present our studies about the molecular architecture and function of the cytomatrix of the nerve cells. The nerve cell is a highly polarized cell composed of highly branched dendrites, cell body, and a single long axon along the direction of the impulse propagation. Each part of the neuron takes characteristic shapes for which the cytoskeleton provides the framework. The neuronal cytoskeletons play important roles on neuronal morphogenesis, organelle transport and the synaptic transmission. In the axon neurofilaments (NF) form dense arrays, while microtubules (MT) are arranged as small clusters among the NFs. On the other hand, MTs are distributed uniformly, whereas NFs tend to run solitarily or form small fascicles in the dendrites Quick freeze deep etch electron microscopy revealed various kinds of strands among MTs, NFs and membranous organelles (MO). These structures form major elements of the cytomatrix in the neuron. To investigate molecular nature and function of these filaments first we studied molecular structures of microtubule associated proteins (MAP1A, MAP1B, MAP2, MAP2C and tau), and microtubules reconstituted from MAPs and tubulin in vitro. These MAPs were all fibrous molecules with different length and formed arm like projections from the microtubule surface.

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