scholarly journals THE EFFECT OF THE ELECTRON-OPAQUE PORE MATERIAL ON EXCHANGES THROUGH THE NUCLEAR ANNULI

1965 ◽  
Vol 25 (1) ◽  
pp. 43-53 ◽  
Author(s):  
Carl M. Feldherr
Keyword(s):  
Particle Size ◽  
Electron Microscope ◽  
Nuclear Envelope ◽  
Colloidal Gold ◽  
Maximum Size ◽  
Amoeba Proteus ◽  
Gold Particles ◽  
High Concentrations

To investigate the extent to which the electron-opaque pore material can regulate nucleocytoplasmic exchanges which occur through the nuclear annuli, experiments were performed in which polyvinylpyrrolidone (PVP)-coated colloidal gold particles (25 to 170 A in diameter) were microinjected into the cytoplasm of amebas (Amoeba proteus). The cells were fixed at various times after injection and examined with the electron microscope in order to determine the location of the gold particles. High concentrations of gold were found associated with the pore material at specific points adjacent to and within the pores. It is tentatively suggested that such specific accumulations could be a means of selecting substances from the cytoplasm for transport through the pores. Particles were also scattered throughout the ground cytoplasm and nucleoplasm. A comparison of the diameters of particles located in these two regions showed that the ability of materials to penetrate the nuclear envelope is a function of their size. It was estimated that the maximum size of the particles able to enter the nucleus is approximately 125 to 145 A indiameter. The regulation of exchanges with regard to particle size is thought to be dependent on the specific organization of the electron-opaque pore material.

scholarly journals NUCLEOCYTOPLASMIC EXCHANGES DURING EARLY INTERPHASE

1968 ◽  
Vol 39 (1) ◽  
pp. 49-54 ◽  
Author(s):  
Carl M. Feldherr
Keyword(s):  
Electron Microscope ◽  
Nuclear Envelope ◽  
Colloidal Gold ◽  
Inverse Relationship ◽  
Amoeba Proteus ◽  
Honeycomb Structure ◽  
Data Support ◽  
Interphase Cells

Colloidal gold was injected into the cytoplasm of amebae (Amoeba proteus) approximately 5 min, 1 hr, and 2 hr after cytokinesis. Later, interphase cells were similarly treated. All of the amebae were fixed about 50 min after injection and were examined with the electron microscope in order to determine the distribution of the gold. It was found that for a period of 2 hr after division the uptake of gold by the nuclei was significantly greater than that during late interphase. Correlation of the gold distribution with the morphology of the nuclear envelope indicated that an inverse relationship exists between the rate of incorporation of colloid into the nucleoplasm and the degree of reconstitution of the fibrous lamina ("honeycomb" structure). These data support the view that the fibrous lamina functions in regulating nucleocytoplasmic exchanges.

scholarly journals Selective binding, uptake, and retrograde transport of tetanus toxin by nerve terminals in the rat iris. An electron microscope study using colloidal gold as a tracer

1978 ◽  
Vol 77 (1) ◽  
pp. 1-13 ◽  
Author(s):  
ME Schwab ◽  
H Thoenen
Keyword(s):  
Electron Microscope ◽  
Tetanus Toxin ◽  
Colloidal Gold ◽  
Smooth Endoplasmic Reticulum ◽  
Specific Binding ◽  
Retrograde Transport ◽  
Nerve Terminals ◽  
Gold Complexes ◽  
Selective Binding ◽  
Gold Particles

A series of specific macromolecules (tetanus toxin, cholera toxin, nerve growth factor [NGF], and several lectins) have been shown to be transported retrogradely with high selectivity from terminals to cell bodies in various types of neurons. Under identical experimental conditions (low protein concentrations injected), most other macromolecules, e.g. horseradish peroxidase (HRP), albumin, ferritin, are not transported in detectable amounts. In the present EM study, we demonstrate selective binding of tetanus toxin to the surface membrane of nerve terminals, followed by uptake and subsequent retorgrade axonal transport. Tetanus toxin or albumin was adsorbed to colloidal gold particles (diam 200 A). The complex was shown to be stable and well suited as an EM tracer. 1-4 h after injection into the anterior eye chamber of adult rats, tetanus toxin-gold particles were found to be selectively associated with membranes of nerve terminals and preterminal axons. Inside terminals and axons, the tracer was localized mainly in smooth endoplasmic reticulum (SER)-like membrane compartments. In contrast, association of albumin-gold complexes with nervous structures was never observed, in spite of extensive uptake into fibroblasts. Electron microscope and biochemical experiments showed selective retrograde transport of tetanus toxin-gold complexes to the superior cervical ganglion. Specific binding to membrane components at nerve terminals and subsequent internalization and retrograde transport may represent an important pathway for macromolecules carrying information from target organs to the perikarya of their innervating neurons.

scholarly journals THE NUCLEAR ANNULI AS PATHWAYS FOR NUCLEOCYTOPLASMIC EXCHANGES

1962 ◽  
Vol 14 (1) ◽  
pp. 65-72 ◽  
Author(s):  
Carl M. Feldherr
Keyword(s):  
Electron Microscopy ◽  
Nuclear Envelope ◽  
Colloidal Gold ◽  
Colloidal Particles ◽  
Time Interval ◽  
Central Channel ◽  
Time Intervals ◽  
Gold Particles ◽  
Pass Through ◽  
Individual Particles

Colloidal gold particles, 25 to 55 A in diameter, which had been coated with polyvinylpyrrolidone, were microinjected into the ground cytoplasm of amebas (Chaos chaos). At time intervals of 1 minute, 2 minutes, 10 minutes, and 24 hours after injection the cells were fixed for electron microscopy. After 24 hours, gold particles were found in both the nuclei and the ground cytoplasm, the concentration being higher in the nuclei. Colloidal particles were also present in the nuclei after 10 minutes, but at this time interval the concentration did not appear to be greater than that in the ground cytoplasm. One and 2 minutes after injection, the gold particles were located almost exclusively in the ground cytoplasm; however, individual particles were often found within the annuli of the nuclear envelope, and were located specifically in the centers of these structures. The results suggest that at least some of the gold particles which enter the nuclei pass through the annuli, and that passage through these structures may be restricted to a central channel.

scholarly journals ELECTRON MICROSCOPIC STUDIES OF MITOSIS IN AMEBAE

1960 ◽  
Vol 8 (1) ◽  
pp. 207-220 ◽  
Author(s):  
L. E. Roth ◽  
S. W. Obetz ◽  
E. W. Daniels
Keyword(s):  
Electron Microscope ◽  
Nuclear Envelope ◽  
Osmium Tetroxide ◽  
Thin Sheet ◽  
Amoeba Proteus ◽  
Electron Microscopic ◽  
Interphase Nuclei ◽  
Nucleolar Material ◽  
Microscopic Studies ◽  
Early Reconstruction

Individual organisms of Amoeba proteus have been fixed in buffered osmium tetroxide in either 0.9 per cent NaCl or 0.01 per cent CaCl2, sectioned, and studied in the electron microscope in interphase and in several stages of mitosis. The helices typical of interphase nuclei do not coexist with condensed chromatin and thus either represent a DNA configuration unique to interphase or are not DNA at all. The membranes of the complex nuclear envelope are present in all stages observed but are discontinuous in metaphase. The inner, thick, honeycomb layer of the nuclear envelope disappears during prophase, reappearing after telophase when nuclear reconstruction is in progress. Nucleoli decrease in size and number during prophase and re-form during telophase in association with the chromatin network. In the early reconstruction nucleus, the nucleolar material forms into thin, sheet-like configurations which are closely associated with small amounts of chromatin and are closely applied to the inner, partially formed layer of the nuclear envelope. It is proposed that nucleolar material is implicated in the formation of the inner layer of the envelope and that there is a configuration of nucleolar material peculiar to this time. The plasmalemma is partially denuded of its fringe-like material during division.

Characterization of beam-induced thinning and shrinkage of semi-thick sections in the HVEM

1990 ◽  
Vol 48 (3) ◽  
pp. 752-753
Author(s):  
J.R. Kremer ◽  
E.T. O'Toole ◽  
G.P. Wray ◽  
D.M. Mastronarde ◽  
S.J. Mitchell ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Colloidal Gold ◽  
Similar Data ◽  
Thin Sections ◽  
Gold Particles ◽  
Dose Rates ◽  
Transmission Electron ◽  
Conventional Transmission Electron Microscope

It is well known that irradiation of plastic sections in a conventional transmission electron microscope (cTEM) causes specimen thinning and distortion. Thinning has been observed in the cTEM using several embedding media, using methods such as shrinkage of ordered paracrystalline structures, and shrinkage of sections coated with colloidal gold markers. The total thinning observed in the cTEM (80kev) is 30-50% for thin sections of epon araldite, but similar data do not exist for the HVEM at 1000 kev. Here we describe beam induced thinning and shrinkage of 0.2um sections in the HVEM.Experiments were performed using 0.2um sections of EPOX 812/Araldite or LX112 with 15 nm and 30 nm gold particles affixed to either surface of the section. The sections were initially tilted to approximately 25° and irradiated with known dose rates. Micrographs were taken at different times between 0-20 minutes then the sections were tilted back to 0° for a reference micrograph.

Improvement of immunogold labeling by using silver-enhanced ultra small gold probes

1990 ◽  
Vol 48 (3) ◽  
pp. 862-863
Author(s):  
Paul M.P. van Bergen en Henegouwen ◽  
Arjan de Graaf ◽  
Mia de Ruijter ◽  
Arie J. Verkleij
Keyword(s):  
Particle Size ◽  
Electron Microscope ◽  
Immunoelectron Microscopy ◽  
Colloidal Gold ◽  
Immunogold Labeling ◽  
Matrix Proteins ◽  
Small Particles ◽  
Major Disadvantage ◽  
Silver Precipitation ◽  
Gold Probe

Colloidal gold is an excellent marker in immunoelectron microscopy for the localization of proteins in cells and tissues. It can be used in pre-embedment labeling (i.e. cellular matrix labeling) and post-embedment labeling (i.e. cryoultramicrotomy). The major disadvantage of the immunogold probe concerns its sensitivity. Pre-embedment labeling of matrix proteins can only be performed when strong extraction conditions are used. In post-embedment labeling, labeling efficiency is rather low as a result of poor penetration of the gold probe into the section. Here, labeling efficiency has been shown to be inversely related to particle size. An improvement of labeling efficiency can be expected by using ultra small gold probes with a diameter of 1 nm. For visualization, these small particles have to be enlarged by silver precipitation both for aplications in the light- and in the electron microscope. Silver precipitation is done according the method described by Danscher.

Correlative Neutron Activation and TEM to Determine the Uptake Mechanism and Distribution of Orally Administered Colloidal Gold Nanoparticles

2000 ◽  
Vol 6 (S2) ◽  
pp. 1006-1007
Author(s):  
J.F. Hillyer ◽  
R.M. Albrecht
Keyword(s):  
Particle Size ◽  
Digestive Tract ◽  
Colloidal Gold ◽  
Oral Delivery ◽  
The Body ◽  
Uptake Mechanism ◽  
Gold Particles ◽  
Particle Uptake ◽  
Size Dependent ◽  
Colloidal Gold Nanoparticles

The uptake of insoluble, particulate matter through the digestive tract occurs in low quantities, and the pathway and amount of particle uptake is size dependent. Previous studies have shown that the uptake of nanoparticles occurs mainly through the Peyer's patch regions of the small intestine while micrometer sized particles enter the body by a process called persorption: the paracellular uptake of microparticles from the digestive tract into the body. These studies have also shown that translocation is largely dependent on particle size: smaller particles are more readily absorbed. Research on the use of microparticles for the oral delivery of drugs, vaccines, and DNA have shown that protein, polysaccharide, and DNA microparticle encapsulation can increase uptake and bioavailability of absorbed molecules. All of these studies have used particles with diameters ranging from 0.1 to 10 μm. Metallic colloidal gold particles can be synthesized in sizes much smaller than micro- and nanoparticles currently being tested for drug delivery.

Ultrastructural analysis of the spatial distribution of MRNA

1992 ◽  
Vol 50 (1) ◽  
pp. 552-553
Author(s):  
Gary Bassell ◽  
Robert H. Singer
Keyword(s):  
Electron Microscopy ◽  
Spatial Distribution ◽  
In Situ Hybridization ◽  
High Resolution ◽  
Nucleic Acids ◽  
Colloidal Gold ◽  
Dna Probe ◽  
Nucleotide Analogs ◽  
Gold Particles

We have been investigating the spatial distribution of nucleic acids intracellularly using in situ hybridization. The use of non-isotopic nucleotide analogs incorporated into the DNA probe allows the detection of the probe at its site of hybridization within the cell. This approach therefore is compatible with the high resolution available by electron microscopy. Biotinated or digoxigenated probe can be detected by antibodies conjugated to colloidal gold. Because mRNA serves as a template for the probe fragments, the colloidal gold particles are detected as arrays which allow it to be unequivocally distinguished from background.

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