Ribosome Crystals in Necrotizing Cells from the Posterior Necrotic Zone of the Developing Chick Limb

1972 ◽  
Vol 11 (2) ◽  
pp. 403-414
Author(s):  
N. K. MOTTET ◽  
S. P. HAMMAR
Keyword(s):  
Electron Micrographs ◽  
Protein Crystals ◽  
Embryonic Chick ◽  
3 Dimensional ◽  
Surface Lattice ◽  
Plane Group ◽  
High Doses ◽  
In Cells

Ribosome and ‘protein crystals" were observed in electron micrographs of degenerating cells from the posterior necrotic zone (PNZ) of developing chick limbs, stages 22 through 24. Ribosome crystals were made up of basic units of 4 ribosomes arranged in a square tetramer. They were monomorphic with the surface lattice being of the p4 plane group. The 1-ribosome-thick sheets of crystals were often seen stacked upon one another forming a 3-dimensional P422 configuration. The percentage of crystallized ribosomes within degenerating PNZ cells is nearly directly proportional to the degree of degeneration of the cell. Crystals identical to this have been observed in numerous types of embryonic chick cells subjected to hypothermia. The ‘protein crystals’ were composed of straight filamentous structures separated by a distance of 20-30 nm. They were always closely associated with the ribosome crystals. These crystals are similar to those seen in cells treated with high doses of vinblastine and vincristine. The pathogenesis of the ribosome and protein crystals occurring in degenerating PNZ cells is unknown. They are not associated in any way with hypothermia or vinblastine-vincristine treatment.

Relationships between mitochondrial outer membranes and agranular reticulum in nervous tissue: ultrastructural observations and a new interpretation

1980 ◽  
Vol 46 (1) ◽  
pp. 129-147
Author(s):  
J. Spacek ◽  
A.R. Lieberman
Keyword(s):  
Nervous Tissue ◽  
Mitochondrial Membrane ◽  
Nerve Cells ◽  
Outer Mitochondrial Membrane ◽  
Inner Mitochondrial Membrane ◽  
Thin Sections ◽  
3 Dimensional ◽  
Outer Membranes ◽  
New Interpretation ◽  
In Cells

This study is concerned with extensions of the outer membranes of mitochondria in cells of nervous tissue, and with possible relationships between the extensions and the agranular reticulum. A variety of preparative techniques was applied to a large number of different central nervous tissues (CNS) and peripheral nervous tissues (PNS), using conventional thin sections, thicker sections (100 nm or more) and 3-dimensional reconstructions of serial thin sections. Extensions were commonly observed, particularly from the ends of longitudinally oriented mitochondria in axons and dendrites. Often these had the appearance of, and could be traced into apparent continuity with, adjacent elements of the agranular membrane. In addition to these apical tubular extensions, we also observed and reconstructed short lateral tubular or sac-like extensions and vesicular protrusions of the outer mitochondrial membrane. We discuss and discount the possibility that the extensions are artefacts, consider the structural and biochemical similarities between the outer mitochondrial membrane and agranular reticulum and propose that the outer mitochondrial is part of the agranular reticulum (or a specialized portion of the agranular reticulum). We suggest that the translocation of mitochondria in nerve cells, and probably in other cells as well, involves movement of the inner mitochondrial membrane and the enclosed matrix (mitoplast) within channels of agranular reticulum in continuity, or in transient continuity, with the outer mitochondrial membrane.

scholarly journals High Doses of Dexamethasone Induce Endoplasmic Reticulum Stress-Mediated Apoptosis by Promoting Calcium Ion Influx-Dependent CHOP Expression in Osteoblasts

2021 ◽  
Author(s):  
Yunshan Guo ◽  
Dingjun Hao
Keyword(s):  
Endoplasmic Reticulum ◽  
Endoplasmic Reticulum Stress ◽  
Cell Apoptosis ◽  
Calcium Ion ◽  
Caspase 3 ◽  
Combined Treatment ◽  
Caspase 12 ◽  
Ion Influx ◽  
High Doses ◽  
In Cells

Abstract Background: The molecular mechanisms by which dexamethasone (Dex) induces apoptosis in osteoblasts remain unclear.Materials and Methods: MC3T3-E1 cells were treated with 0, 10-8, 10-6, and 10-4 M Dex for 24 h. The expression of ATF6, and phosphorylated PERK and IRE1, cell apoptosis, and the activity of caspase-12 and caspase-3 were measured. The expression of CHOP and the rate of influx of calcium ions were also measured in cells treated with 0 and 10-4 M Dex for 24 h. The effect of 2-APB treatment was assessed in cells treated with 0 or 10-4 M Dex.Results: The levels of ATF6 and phosphorylated PERK and IRE1 increased in a dose-dependent manner in MC3T3-E1 cells treated with 10-8, 10-6, and 10-4 M Dex, compared to in cells treated with 0 M Dex (P <0.05). Cells treated with 10-6 and 10-4 M Dex had significantly increased cell apoptosis rates and caspase-12 and caspase-3 activity compared to the control (P <0.05). Cells treated with 10-4 M Dex had significantly increased levels of CHOP and calcium ion influx rates compared to in the control (P <0.05). Combined treatment with 10-4 M Dex and 2-APB abrogated the observed increases in cell apoptosis and the activity of caspase-12 and caspase-3 (P>0.05). Conclusion: High doses of Dex induce endoplasmic reticulum stress-mediated apoptosis by promoting calcium ion influx-dependent expression of CHOP, and the activation of caspase-12 and caspase-3 in osteoblasts. Combined treatment with 2-APB protects the cells from the effects of Dex, preventing endoplasmic reticulum stress-mediated apoptosis.

A model for the topology of the chloroplast thylakoid membrane

1999 ◽  
Vol 26 (7) ◽  
pp. 687 ◽  
Author(s):  
Per-Ola Arvidsson ◽  
Cecilia Sundby
Keyword(s):  
Cross Section ◽  
Electron Micrographs ◽  
Thylakoid Membrane ◽  
Dimensional Structure ◽  
Cross Sectional ◽  
3 Dimensional ◽  
Topological Organization

A model for the topological organization of the chloroplast thylakoid membrane is presented. A series of illustrations is provided, which outline a suggested 3-dimensional structure in cross-section and in full shape, which accounts both for the folding of one continuous membrane into multiple grana stacks as seen in cross-sectional electron micrographs and for the rapid reversible unfolding (destacking) of the grana stacks into lamellar sheets.

scholarly journals RRAD, IL4I1, CDKN1A, and SERPINE1 genes are potentially co-regulated by NF-κB and p53 transcription factors in cells exposed to high doses of ionizing radiation

BMC Genomics ◽  
2018 ◽  
Vol 19 (1) ◽  
Author(s):  
Katarzyna Szołtysek ◽  
Patryk Janus ◽  
Gracjana Zając ◽  
Tomasz Stokowy ◽  
Anna Walaszczyk ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Ionizing Radiation ◽  
High Doses ◽  
In Cells

scholarly journals 3D Reconstruction of Protein Kinase C Molecules From Electron Micrographs Of Two-Dimensional Crystals On Lipid Monolayers In Plane Group p1

2006 ◽  
Vol 12 (S02) ◽  
pp. 410-411
Author(s):  
AS Solodukhin ◽  
RH Kretsinger ◽  
JJ Sando
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
3D Reconstruction ◽  
Electron Micrographs ◽  
Lipid Monolayers ◽  
Two Dimensional ◽  
Kinase C ◽  
Plane Group

Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2005

Effects of calcium channel blockers on spontaneous electrical activity of freshly isolated three-day-old embryonic chick ventricle

1996 ◽  
Vol 8 (5) ◽  
pp. 921 ◽  
Author(s):  
P Prakash ◽  
P Meera ◽  
O Tripathi
Keyword(s):  
Na Channel ◽  
Channel Blockers ◽  
Dependent Manner ◽  
Embryonic Chick ◽  
Na Channels ◽  
Chronotropic Effect ◽  
High Doses ◽  
Dose Dependent ◽  
Ca2 Channels ◽  
Positive Chronotropic Effect

The effects of four major types of organic Ca2+ channel blockers, verapamil, nifedipine, diltiazem and fendiline and of tetrodotoxin (TXX), a fast Na+ channel blocker, on the action potential (AP) of freshly isolated 3-day-old embryonic chick ventricle (3d ECV) were investigated to resolve the controversy about the ionic basis of upstroke. The APs were characterized by a maximum diastolic potential (MDP) of -60 mV, an overshoot (Eov) of 16 mV and a maximum upstroke velocity (+Vmax) of 42 V s-1. All four Ca2+ channel blockers (0.1-40 microM) and TTX (0.1-80 nM) produced a dose-dependent reduction in +Vmax and Eov. MDP was also reduced by Ca2+ channel blockers in a dose-dependent manner but was unaffected by TTX. A significant linear correlation between MDP and +Vmax was observed for verapamil (r = 0.99), nifedipine (r = 0.99), diltiazem (r = 0.96) and fendiline (r = 0.98). Surprisingly, all Ca2+ channel blockers produced a dose-dependent positive chronotropic effect leading to cessation of firing at high doses (20-40 microM). In preparations becoming quiescent with high doses of verapamil (20-40 microM), elevated extracellular concentrations of Ca2+ (up to 9.6 nM) and isoproterenol (0.5-40 microM) failed to restore spontaneous APs. Electrical stimulation also failed to elicit APs in preparations inhibited by verapamil, diltiazem and fendiline. The inhibition of +Vmax by TTX demonstrates that fast Na+ channels were involved in the upstroke of AP in 3d ECV. Voltage-dependent inactivation of fast Na+ channels during depolarization (reduction in MDP) by the Ca2+ channel blockers explains their inhibitory effect on +Vmax and indicates that L-type Ca2+ channels had no significant role in the upstroke. A positive chronotropic effect of the Ca2+ channel blockers further suggests that slow Ca2+ channels are not involved in automaticity in freshly isolated 3d ECV.

Protein electron crystallography by 400kV cryo-microscopy

1992 ◽  
Vol 50 (2) ◽  
pp. 1054-1055
Author(s):  
Wah Chiu ◽  
Jaap Brink ◽  
Toshinori Soejima ◽  
Michael F. Schmid
Keyword(s):  
Electron Microscope ◽  
Polypeptide Chain ◽  
Three Dimensional ◽  
Chromatic Aberration ◽  
Protein Crystals ◽  
Electron Crystallography ◽  
Technical Problems ◽  
3 Dimensional ◽  
Experimental Strategy ◽  
Complex Forms

Protein electron crystallography can provide a reconstruction detailed enough for the polypeptide chain of a membrane protein to be traced (1). However, there remain a number of technical problems associated with this technique that must be overcome before it can become a routine tool for high resolution three-dimensional structural analysis of protein crystals. A 400 kV electron microscope has been demonstrated to be advantageous for enhancement of resolution and contrast in images of protein crystals (1,2) because of a reduction in chromatic aberration effects. This paper addresses the question of experimental strategy in data collection for thin protein crystals with a 400 kV cryo-microscope. We will use crotoxin complex and T4 DNA helix destabilizing protein as examples of thin crystals to illustrate our approach.Crotoxin complex forms highly ordered crystals with different thicknesses among different crystals. In order to simplify sorting out data from the various crystals for 3-dimensional merging, it is desirable to collect as much data as possible from a single crystal.

scholarly journals MICROTUBULE SURFACE LATTICE AND SUBUNIT STRUCTURE AND OBSERVATIONS ON REASSEMBLY

1974 ◽  
Vol 60 (1) ◽  
pp. 153-167 ◽  
Author(s):  
Harold P. Erickson
Keyword(s):  
Brain Tissue ◽  
Electron Micrographs ◽  
Optical Diffraction ◽  
Reconstructed Image ◽  
Subunit Structure ◽  
Flat Sheet ◽  
Surface Lattice ◽  
Tissue Homogenates ◽  
Globular Particle

Neuronal microtubules have been reassembled from brain tissue homogenates and purified. In reassembly from purified preparations, one of the first structures formed was a flat sheet, consisting of up to 13 longitudinal filaments, which was identified as an incomplete microtubule wall. Electron micrographs of these flat sheets and intact microtubules were analyzed by optical diffraction, and the surface lattice on which the subunits are arranged was determined to be a 13 filament, 3-start helix. A similar, and probably identical, lattice was found for outer-doublet microtubules. Finally, a 2-D image of the structure and arrangement of the microtubule subunits was obtained by processing selected images with a computer filtering and averaging system. The 40 x 50 Å morphological subunit, which has previously been seen only as a globular particle and identified as the 55,000-dalton tubulin monomer, is seen in this higher resolution reconstructed image to be elongated, and split symmetrically by a longitudinal cleft into two lobes.

scholarly journals Changes in the nuclear polyamine content of chick erythrocytes during embryonic development

1979 ◽  
Vol 184 (3) ◽  
pp. 607-612 ◽  
Author(s):  
M H Goyns
Keyword(s):  
Embryonic Development ◽  
Metabolic Activity ◽  
Embryonic Chick ◽  
Polyamine Content ◽  
In Cells

The polyamine content of the circulating erythrocyte population in the embryonic chick was studied during its development. Total cellular polyamine content fell dramatically between 5 and 7 days of development, paralleling the decrease in metabolic activity exhibited by these cells. Nuclei were isolated from the erythrocytes by a non-aqueous technique, which not only eliminated the polyamine loss that occurred with aqueous isolation, but also prevented redistribution of the polyamines from the cytoplasm. Nuclear spermidine and spermine contents decreased markedly between 5 and 6 days of development from 31 to 10 pmol/microgram of DNA and from 33 to 18 pmol/microgram of DNA respectively. Thereafter the spermine content remained constant, but the spermidine content continued to decline. Good correlations between spermidine and RNA contents were observed in both cells and nuclei, and similarly between spermine and RNA contents in cells, but no such correlation was observed between spermine and RNA in nuclei.

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