Microfilaments and Cytoplasmic Streaming: Inhibition of Streaming with Cytochalasin

1973 ◽  
Vol 12 (1) ◽  
pp. 327-343
Author(s):  
M. O. BRADLEY
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Synthesis ◽  
Cytoplasmic Streaming ◽  
Cytochalasin B ◽  
Animal Cell ◽  
The Other ◽  
Ultrastructural Changes ◽  
Ultrastructural Studies ◽  
Functional Inhibition ◽  
Cross Bridges

Cytochalasin B reversibly inhibits cytoplasmic streaming in both Nitella and Avena cells. Colchicine, on the other hand, has no effect on streaming in either plant; nor does colchicine prevent the recovery of streaming after cytochalasin is withdrawn. The inhibition of protein synthesis by cycloheximide has no effect on either streaming itself or on the recovery of streaming after cytochalasin withdrawal. All this suggests that microfilaments may provide one component of the structure that generates the streaming force and that microtubules play little, if any,role in the process. Ultrastructural studies of Nitella demonstrate that microfilaments are localized at the boundary of the streaming endoplasm and the stationary ectoplasm. Microfilaments are organized in discrete bundles, with possible cross-bridges between individual filaments in each bundle. These bundles are closely associated with the extensive endoplasmic reticulum. Cytochalasin B does not cause ultrastructural changes in Nitella microfilaments as it does in some animal-cell filaments. Since the molecular mechanism of cytochalasin's action is unknown, there may be no necessary correlation between functional inhibition by the drug and altered microfilament morphology. A model is advanced which proposes that streaming is generated by an interaction between microfilaments and the endoplasmic reticulum.

Cytoplasmic streaming in Elodea

1976 ◽  
Vol 54 (23) ◽  
pp. 2688-2694 ◽  
Author(s):  
Janice Forde ◽  
Martin W. Steer
Keyword(s):  
Endoplasmic Reticulum ◽  
Cytoplasmic Streaming ◽  
Cytochalasin B ◽  
Ethylenediaminetetraacetic Acid ◽  
Light And Electron Microscopy ◽  
Chloride Ions ◽  
Magnesium Ions ◽  
Higher Plant ◽  
Ultrastructural Studies ◽  
Detached Leaves

Cytoplasmic streaming in the higher plant Elodea canadensis has been studied by light and electron microscopy. Calcium ions inhibited streaming in detached leaves, whereas magnesium ions stimulated the streaming rate. Ethylenediaminetetraacetic acid (EDTA) at low concentrations relieved calcium ion inhibition, while at higher concentrations it inhibited the magnesium ion stimulation. Chloride ions had a slight dual effect, accentuating the differences produced by calcium and magnesium ions. Cytoplasmic streaming was reversibly inhibited by cytochalasin B, although there was a considerable delay in these effects. Possible binding sites for cytochalasin B were localized using light microscope autoradiography of leaf sections. Vacuoles, cell walls, and nuclei were unlabelled; chloroplasts were labelled to a limited extent, while the rest of the label was distributed throughout the cytoplasm. Ultrastructural studies failed to reveal large aggregates of microfilaments; instead much smaller bundles were found together with a fibrillar-granular material associated with the endoplasmic reticulum. The possibility that this material generates cytoplasmic streaming by imparting movement to the endoplasmic reticulum is considered.

Ultrastructural changes accompany inhibition of proteoglycan synthesis in chondrocytes by Cyclofenil diphenol

1989 ◽  
Vol 92 (2) ◽  
pp. 271-280 ◽  
Author(s):  
C.A. Lancaster ◽  
P.R. Fryer ◽  
S. Griffiths ◽  
R.M. Mason
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Synthesis ◽  
Electron Density ◽  
Lipid Droplets ◽  
Secretory Pathway ◽  
Ultrastructural Changes ◽  
Proteoglycan Synthesis ◽  
Filamentous Material

Cyclofenil diphenol, a weak non-steroidal oestrogen, profoundly inhibits [35S]proteoglycan synthesis in cultures of Swarm chondrosarcoma chondrocytes under conditions in which protein synthesis is only marginally reduced. In the present experiments it was shown that after a 40-min treatment with Cyclofenil diphenol (90 micrograms ml-1) most of the normally abundant Golgi stacks in these cells disappeared and after 60 min they were absent. After 2–3 h treatment the cisternae of the endoplasmic reticulum (ER) were grossly distended and transformed into large ribosome-studded vesicles containing flocculent and filamentous material. These changes were dependent on the concentration of Cyclofenil and were fully reversible within 21 h of withdrawing the drug. The ultrastructural changes differed in some aspects if protein synthesis was blocked with cycloheximide for 15 min or 180 min before and during treatment with Cyclofenil. The Golgi disappeared but the ER cisternae, though distended, formed a continuous network and swollen ribosome-studded vesicles did not develop. However, non-membrane-bounded structures containing lipid droplets and material of low electron density developed in the cytoplasm under these conditions. The ultrastructural changes induced by Cyclofenil differ from those induced by monensin and diethylcarbamazine, suggesting that the drug acts at a different point in the secretory pathway for macromolecules.

Ultrastructural changes in tissues of larval Elateridae (Coleoptera) infected with the fungus Metarrhizium anisopliae

1971 ◽  
Vol 17 (2) ◽  
pp. 281-289 ◽  
Author(s):  
R. Y. Zacharuk
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Fat Body ◽  
Malpighian Tubule ◽  
Malpighian Tubules ◽  
The Other ◽  
Host Cells ◽  
Ultrastructural Changes ◽  
Host Death ◽  
Host Tissues

The ultrastructural changes that occur in the cells of the hypodermis, fat body, Malpighian tubule, midgut, ventral abdominal ganglion, and muscle during mycoses in three species of elaterid larvae infected with Metarrhizium anisopliae are described. The fungus penetrated all the above tissues before host death in most of the larvae examined. In some infected larvae, however, particularly in the smaller individuals or species, only the hypodermal and fat tissues were penetrated before death. Changes in fine structure appear in all the tissues soon after the fungus enters the hemocoel, even when no fungal growths are present near the host cells. In general, there is initially an increase in the number of lysosomes and of endoplasmic reticulum and ribosomes, followed by a vesiculation of the endoplasmic reticulum and of the cristae of the mitochondria and a progressive vacuolation of the cytoplasm. In some tissues the mitochondria increase in number before vesiculation. Glycogen granules and lipid and oil inclusions disappear rapidly during mycosis. Clear, membrane-limited vacuoles become particularly abundant in the Malpighian tubules and the midgut, suggesting increased secretion of fluids into their lumens. At or soon after death, the lysosomes disappear and all the membranous structures of the cells are disrupted, and laminated or whorled bodies of thickened membranes become numerous. Disintegration of all tissues, including muscle and nerve, was extensive in some larvae that were still capable of some sluggish movement before fixation for the study. It is suggested that the fungus incites lysosome production by the host tissues along with the other initial changes observed, and that final disintegration of the host tissues is by a process of autohistolysis.

scholarly journals NEURONAL PERIKARYA WITH DISPERSED, SINGLE RIBOSOMES IN THE VISUAL CORTEX OF MACACA MULATTA

1974 ◽  
Vol 63 (3) ◽  
pp. 1074-1089 ◽  
Author(s):  
S. L. Palay ◽  
S. Billings-Gagliardi ◽  
V. Chan-Palay
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Synthesis ◽  
Visual Cortex ◽  
Golgi Apparatus ◽  
Metabolic Activity ◽  
Macaca Mulatta ◽  
The Other ◽  
Cytoplasmic Matrix ◽  
Unusual Pattern ◽  
Intermediate Cells

Numerous small and medium-sized neuronal perikarya in layers III and IV of the visual cortex display an unusual pattern of ribosomal distribution. Instead of being aggregated in clusters, spirals, rows, and other regular polysomal configurations, the ribosomes, whether free or attached to the endoplasmic reticulum, are randomly dispersed, with no discernible pattern. The endoplasmic reticulum in such cells is reduced to a few (perhaps only one) meandering, broad cisternae, which delimit broad fields of cytoplasmic matrix occupied almost solely by scattered, single ribosomes. The Golgi apparatus is elaborate. Mitochondria are either small and numerous or large and infrequent. The other organelles, including the nucleus and nucleolus, are not remarkable. Axonal terminals synapse in the normal fashion on the surfaces of these cells and their dendrites. Associated with these cells are more numerous intermediate cells in which a few to many polysomal clusters can be found. It is proposed that the neurons with dispersed, single ribosomes are inactive in protein synthesis and that the suspension of such an important metabolic activity is probably temporary. Thus, these cells are considered to be part of a population undergoing cyclic fluctuations in the intensity of protein synthesis that should be correlated with their specific neural behavior.

Transport of fluorescein in trichomes of Lycopersicon esculentum

1982 ◽  
Vol 60 (4) ◽  
pp. 397-402 ◽  
Author(s):  
Gregor F. Barclay ◽  
Carol A. Peterson ◽  
Melvin T. Tyree
Keyword(s):  
Lycopersicon Esculentum ◽  
Cytoplasmic Streaming ◽  
Cytochalasin B ◽  
The Other ◽  
Square Root ◽  
Inhibiting Effect ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Other Hand ◽  
Rate Limiting

Translocation of the dye disodium fluorescein (uranin) in trichomes of Lycopersicon esculentum (tomato) was nonpolar and proportional to the square root of time. Inhibition of cytoplasmic streaming by cytochalasin B had no effect on the rate of dye movement. On the other hand, disruption of plasmodesmatal connections between adjacent cells by plasmolysis strongly diminished the rate of fluorescein translocation. Subsequent deplasmolysis of the cells did not remove the inhibiting effect of plasmolysis. The data are consistent with the interpretation that dye movement proceeds by diffusion, the rate-limiting step being transport through plasmodesmatal connections.

Ultrastructural changes in the rough endoplasmic reticulum and its contents following Brefeldin A treatment of human chondrocytes in vitro

1991 ◽  
Vol 49 ◽  
pp. 256-257
Author(s):  
H. E. Gruber
Keyword(s):  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Secretory Pathway ◽  
Protein Transport ◽  
Brefeldin A ◽  
Ultrastructural Level ◽  
Human Chondrocytes ◽  
Ultrastructural Changes ◽  
Ultrastructural Studies

The rough endoplasmic reticulum (rER) is now recognized as a major organelle responsible for ensuring that only structurally correct and properly folded proteins are allowed to enter the cellular secretory pathway. We are especially interested in the behavior of the chondrocyte rER since ultrastructural studies of many skeletal dysplasias have revealed that electron dense material accumulates or is not degraded within the rER of chondrocytes from patients. Remodelling of the rER in chick chondrocytes has also been evaluated at the ultrastructural level and the rER found to play a role in procollagen export from the cell. We have utilized normal human chondrocytes grown in culture to investigate the role of brefeldin A, an antiviral antibiotic, which has been shown to primarily block protein transport from the ER to the Golgi complex.

The Cellular Origin in Atheromatous Lesion

1970 ◽  
Vol 28 ◽  
pp. 202-203
Author(s):  
T. M. Murad ◽  
H. A. I. Newman ◽  
K. F. Kern
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Rabbit Aorta ◽  
Mixed Population ◽  
The Other ◽  
Cellular Origin ◽  
Ultrastructural Studies ◽  
Atherosclerotic Lesions ◽  
Show Evidence ◽  
Early Lesion

The origin of lipid containing cells in atheromatous lesion has been disputed. Geer in his study on atheromatous lesions of rabbit aorta, suggested that the early lesion is composed mainly of lipid-laden macrophages and the later lesion has a mixed population of macrophages and smooth muscle cells. Parker on the other hand, was able to show evidence that the rabbit lesion is primarily composed of lipid-laden cells of smooth muscle origin. The above studies and many others were done on an intact lesion without any attempt of cellular isolation previous to their ultrastructural studies. Cell isolation procedures have been established for atherosclerotic lesions through collagenase and elastase digestion Therefore this procedure can be utilized to identify the cells involved in rabbit atheroma.

Ultrastructural Changes Associated with Alcoholic Hyalin in Hepatocytes and Biliary Epithelial Cells

1971 ◽  
Vol 29 ◽  
pp. 572-573
Author(s):  
Odell T. Minick ◽  
Hidejiro Yokoo ◽  
Fawzia Batti
Keyword(s):  
Endoplasmic Reticulum ◽  
Epithelial Cells ◽  
Liver Biopsy ◽  
Alcoholic Hepatitis ◽  
Ultrastructural Changes ◽  
Main Mass ◽  
Biliary Epithelial Cells ◽  
Biopsy Specimens ◽  
Alcoholic Hyalin

To learn more of the nature and origin of alcoholic hyalin (AH), 15 liver biopsy specimens from patients with alcoholic hepatitis were studied in detail.AH was found not only in hepatocytes but also in ductular cells (Figs. 1 and 2), although in the latter location only rarely. The bulk of AH consisted of a randomly oriented network of closely packed filaments measuring about 150 Å in width. Bundles of filaments smaller in diameter (40-90 Å) were observed along the periphery of the main mass (Fig. 1), often surrounding it in a rim-like fashion. Fine filaments were also found close to the nucleus in both hepatocytes and biliary epithelial cells, the latter even though characteristic AH was not present (Figs. 3 and 4). Dispersed among the larger filaments were glycogen, RNA particles and profiles of endoplasmic reticulum. Dilated cisternae of endoplasmic reticulum were often conspicuous around the periphery of the AH mass. A limiting membrane was not observed.

Compound Symbiosis in Peridinium Balticum

1973 ◽  
Vol 31 ◽  
pp. 500-501
Author(s):  
R. N. Tomas
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
The Other ◽  
Exact Nature ◽  
Symbiotic Relationship

Peridinium balticum appears to be unusual among the dinoflagellates in that it possesses two DNA-containing structures as determined by histochemical techniques. Ultrastructurally, the two dissimilar nuclei are contained within different protoplasts; one of the nuclei is characteristically dinophycean in nature, while the other is characteristically eucaryotic. The chloroplasts observed within P. balticum are intrinsic to an eucaryotic photosynthetic endosymbiont and not to the dinoflagellate. These organelles are surrounded by outpocketings of endoplasmic reticulum which are continuous with the eucaryotic nuclear envelope and are characterized by thylakoids composed of three apposed lamellae. Girdle lamellae and membranebounded interlamellar pyrenoids are also present. Only the plasmalemma of the endosymbiont segregates its protoplast from that of the dinophycean cytoplasm. The exact nature of this symbiotic relationship is at present not known.

Golgi Apparatus and Melanogenesis: Ultrastructural Study of a Human Cellular Blue Nevus (Melanocytoma)

1973 ◽  
Vol 31 ◽  
pp. 380-381
Author(s):  
S.R. Allegra
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Ultrastructural Study ◽  
The Other ◽  
Blue Nevus ◽  
Normal Complement ◽  
Golgi Vesicles ◽  
Golgi System ◽  
The Subject ◽  
Cellular Blue Nevus

The respective roles of the ribo somes, endoplasmic reticulum, Golgi apparatus and perhaps nucleus in the synthesis and maturation of melanosomes is still the subject of some controversy. While the early melanosomes (premelanosomes) have been frequently demonstrated to originate as Golgi vesicles, it is undeniable that these structures can be formed in cells in which Golgi system is not found. This report was prompted by the findings in an essentially amelanotic human cellular blue nevus (melanocytoma) of two distinct lines of melanocytes one of which was devoid of any trace of Golgi apparatus while the other had normal complement of this organelle.

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