scholarly journals Ultrastructure of Mauthner Cells in Fish Adapted to Long-Duration Vestibular Stimulation and the Effect of Ethanol

1999 ◽  
Vol 6 (4) ◽  
pp. 91-102 ◽  
Author(s):  
Nadezhda R. Tiras ◽  
Georgy V. Zherdev ◽  
Dmitry A. Moshkov
Keyword(s):  
Structural Changes ◽  
Vestibular Stimulation ◽  
Ethanol Exposure ◽  
Ethanol Solution ◽  
M Cells ◽  
M Cell ◽  
Electron Microscopic ◽  
Training Time ◽  
Long Duration ◽  
Main Component

Adaptation or resistance of fish Mauthner cells (M-cells) to long duration (2 h) vestibular stimulation (LDS)was produced by daily brief and gradually increasing vestibular stimulation (training). The LDS resistance was accompanied by an increase in the number of desmosome-like junctions in the afferent axosomatic synapses. F-actin, the main component of desmosome-like contacts, has been suggested to be responsible for the increased resistance of M-cells to LDS. The purpose of the present study was to investigate the capacity of M-cells to adapt to LDS under the influence of ethanol, which alters the content of F-actin in cells. The experiments were carried out in goldfish fry. Vestibular stimulation (training and LDS) was performed in special drums that were rotated in two planes. The training time was increased from 1 min on day 1 to 30 min on day 30. For ethanol exposure, fish were immersed daily in a 2% ethanol solution for 20 min. To assess the level of resistance to LDS, motor activity indicating the functional state of M-cells was evaluated before and after LDS. The results show that exposure to ethanol reduces the resistance to LDS in both untrained and trained fish. Electron microscopic data demonstrated some structural changes in the synaptic endings located on M-cell soma in ethanol-exposed fish. Wrapping of boutons by cytoplasmic out- growths and myelin- like structures was observed. Morphometric analysis revealed that exposure to ethanol without training decreases the number of desmosome-like contacts, probably due to ethanol-induced depolymerization of cytoskeletal actin. Ethanol exposure also partly suppressed the increase in the number of desmosome-like contacts that occurs as a result of training. In ethanol-treated trained fish, however, a concomitant increase in the length of desmosome-like contacts was observed. As training alone leads to the formation of additional desmosome-like contacts of standard length, it is possible that although a sufficient amount of such structures cannot be formed in the M-cells of ethanol-exposed trained fish, the existing contacts can be elongated. Thus, possibly changes of the actin state are involved in the adaptation of M-cells to LDS.

scholarly journals CONTRAST BETWEEN THE ENVIRONMENTAL pH DEPENDENCIES OF PROPHASING AND NUCLEAR MEMBRANE FORMATION IN INTERPHASE-METAPHASE CELLS

1973 ◽  
Vol 58 (3) ◽  
pp. 608-617 ◽  
Author(s):  
Yoshitaka Obara ◽  
Hiroshi Yoshida ◽  
Lee S. Chai ◽  
Herbert Weinfeld ◽  
Avery A. Sandberg
Keyword(s):  
Structural Changes ◽  
Chinese Hamster ◽  
Binucleate Cell ◽  
M Cells ◽  
M Cell ◽  
Metaphase Chromosomes ◽  
Membrane Formation ◽  
Interphase Cell ◽  
Double Membrane ◽  
Mononucleate Cell

In Chinese hamster Don cells, fusion of an interphase cell with a metaphase cell resulted either in prophasing of the interphase nucleus, including loss of the nuclear envelope (NE), or in the formation of a double membrane around the metaphase chromosomes. Only one of these phenomena occurred in a given interphase-metaphase (I–M) binucleate cell. At pH 7.4, there was about an equal probability that either event could occur amongst the population of I–M cells. The effect of pH changes in the medium containing the fused cells was examined. At pH 6.6, prophasing was the predominant event; at pH 8.0, membrane formation predominated. It was found that the rate of progression of a mononucleate cell from G2 to metaphase was appreciably faster at pH 6.6 than at pH 8.0. Conversely, the progression from metaphase to G1 was faster at pH 8.0 than at pH 6.6. These results with the mononucleate cells strengthen the hypothesis that structural changes in I–M cells are reflections of normal mitotic phenomena. Additional evidence for this hypothesis was produced by electron microscope examination after direct fixation in chrom-osmium. The double membrane around the chromosomes of the I–M cell was indistinguishable from the normal NE. The results obtained by varying the pH of the medium containing the fused cells provide an indication that disruption or formation of the NE of Don cells depends on the balance reached between disruptive and formative processes.

Electron microscopic study of the structural changes as a function of temperature in anorthite*

1973 ◽  
Vol 138 (1-4) ◽  
pp. 403-418
Author(s):  
M. Czank ◽  
J. Van Landuyt ◽  
H. Schulz ◽  
F. Laves ◽  
S. Amelinckx
Keyword(s):  
Microscopic Study ◽  
Electron Microscopic Study ◽  
Structural Changes ◽  
Electron Microscopic

New insights into the structural basis of integrin activation

Blood ◽  
2003 ◽  
Vol 102 (4) ◽  
pp. 1155-1159 ◽  
Author(s):  
Jian-Ping Xiong ◽  
Thilo Stehle ◽  
Simon L. Goodman ◽  
M. Amin Arnaout
Keyword(s):  
Conformational Changes ◽  
Structural Changes ◽  
Structural Basis ◽  
Integrin Activation ◽  
Cellular Functions ◽  
Electron Microscopic ◽  
The Past ◽  
Intracellular Signals ◽  
Bidirectional Signaling ◽  
New Hypothesis

Abstract Integrins are cell adhesion receptors that communicate biochemical and mechanical signals in a bidirectional manner across the plasma membrane and thus influence most cellular functions. Intracellular signals switch integrins into a ligand-competent state as a result of elicited conformational changes in the integrin ectodomain. Binding of extracellular ligands induces, in turn, structural changes that convey distinct signals to the cell interior. The structural basis of this bidirectional signaling has been the focus of intensive study for the past 3 decades. In this perspective, we develop a new hypothesis for integrin activation based on recent crystallographic, electron microscopic, and biochemical studies.

Correlation of the startle reflex and Mauthner cell auditory responses in unrestrained goldfish

1977 ◽  
Vol 66 (1) ◽  
pp. 243-254 ◽  
Author(s):  
S. J. Zottoli
Keyword(s):  
Stainless Steel ◽  
Startle Reflex ◽  
Sound Stimulus ◽  
M Cells ◽  
M Cell ◽  
Mauthner Cell ◽  
Auditory Responses ◽  
Cell Electrode ◽  
Steel Electrodes

Stainless-steel electrodes were implanted near the left or right. Mauthner cells (M-cells) of goldfish to determine if these cells can initiate the startle reflex evoked by a brief sinusoidal sound stimulus. Recordings of the M-cell extracellular spike were obtained for the duration of 10 experiments. Fish with chronic implants were allowed to free-swim and exposed to at least 10 consecutive sound stimuli consisting of 2 cycles of 200 Hz. Seventy-three startle responses were analysed. In 34 cases the implanted M-cell electrode was contralateral to the contracting musculature, and in each of these cases, a M-cell spike preceded the EMG response by 1-1-2-1 ms. In the reamining 39 cases the electrode was ipsilateral to the active musculature, and the M-cell only fired in one of these trails. There were no startle responses and no M-cell firings in an additional 52 tests. Since the M-cell activates contralateral motoneurones, the results indicate it is responsible for initiation of the startle reflex.

Rabbit M cells and dome enterocytes are distinct cell lineages

2001 ◽  
Vol 114 (11) ◽  
pp. 2077-2083
Author(s):  
Hugues Lelouard ◽  
Alain Sahuquet ◽  
Hubert Reggio ◽  
Philippe Montcourrier
Keyword(s):  
Lymphoid Tissues ◽  
M Cells ◽  
Relative Distribution ◽  
M Cell ◽  
Epithelial Surface ◽  
Cell Lineages ◽  
Proliferative Zone ◽  
Early Appearance ◽  
Distinct Cell ◽  
Constant Distribution

We have studied the M cell origin and differentiation pathway in rabbit gut-associated lymphoid tissues. Micro-dissected domes and epithelium isolated by ethylene diamine tetra acetic acid detachment allowed us to view the whole epithelial surface from the bottom of crypts to the top of domes. We used monoclonal antibodies specific to the apex of either M cells or dome enterocytes, lectins, and antibodies to vimentin in appendix, distal Peyer’s patches and caecal patches. The earliest vimentin-labeled M cells were observed in the BrdU-positive proliferative zone of dome-associated crypts. Gradual differentiation of the M cell vimentin cytoskeleton started at this site to progressively give rise to the first pocket-forming M cells in the upper dome. Therefore, these mitotic cells of the crypts appear as the direct precursors of M cells. In addition to an early appearance of M cell markers, a regular mosaic-like relative distribution of M cells and dome enterocytes was already detected in the vicinity of crypts, similar to that observed on the lateral surface of domes where functional M cells lie. This constant distribution implies that there is no trans-differentiation of enterocytes to M cells along the crypt-dome axis. Together, these observations provide very strong evidence in favor of an early commitment in crypts of M cell and enterocyte distinct lineages.

scholarly journals The effects of simulated microgravity on skeletal muscle of Japanese quail: transmission electron microscopic study

2011 ◽  
Vol 80 (1) ◽  
pp. 119-124 ◽  
Author(s):  
Katarína Holovská ◽  
Viera Almášiová ◽  
Viera Cigánková ◽  
Peter Škrobánek
Keyword(s):  
Skeletal Muscle ◽  
Japanese Quail ◽  
Structural Changes ◽  
Simulated Microgravity ◽  
Negative Impact ◽  
Electron Microscopic ◽  
Giant Mitochondria ◽  
Transmission Electron ◽  
Muscle Tissues ◽  
And Control

The aim of the present study was to investigate the effects of simulated microgravity (hypodynamia) on the structure of the skeletal muscle (m. gastrocnemius) in developing Japanese quail by transmission electron microscopy. Samples of muscle tissues from experimental (n = 28) and control (n = 28) birds were collected at day 7, 14, 28, 42 and 56 of age. The structure of m. gastrocnenmius was changed depending on hypodynamia length. The first extensive structural changes were found on day 14 of age. The mitochondria were enlarged and the spaces between the myofibrils were slightly extended compared to control. The sarcomeres were irregular and lipid droplets occurred in the sarcoplasm. Further developmental changes occurred on day 28 of age. Mitochondria fused into the giant mitochondria which frequently exceeded the length of one sarcomere. Moreover, at 42 days of age, beside the above mentioned changes, sarcoplasmic reticulum was dilated and the number of mitochondrial cristae was reduced. However, the structure of m. gastrocnemius on day 56 was less damaged compared to the damage observed on day 42 of age. Presented results indicate that the continuous stay of male Japanese quail under simulated microgravity has a negative impact on the structure of m. gastrocnemius, but also the ability of muscle tissue to cope with these specific conditions.

scholarly journals STRUCTURAL CHANGES IN THE MICROCIRCULATORY BED OF THE PANCREAS IN RATS WITH EXPERIMENTAL METABOLIC SYNDROME

2018 ◽  
Vol 15 (3) ◽  
pp. 347-353
Author(s):  
T. E. Kuznetsova ◽  
E. L. Ryzhkovskaya ◽  
E. I. Kalinovskaya
Keyword(s):  
Metabolic Syndrome ◽  
Glucose Oxidation ◽  
Structural Changes ◽  
Krebs Cycle ◽  
Electron Microscopic ◽  
Microcirculatory Bed ◽  
The Metabolic Syndrome ◽  
Marginal State ◽  
Inflammatory Changes ◽  
Blood Elements

A complex histological, histochemical and electron microscopic study of the state of the microcirculatory bed of the pancreas and conjugate transformations in the parenchyma of the organ after modeling the metabolic syndrome using a diet high in fats and carbohydrates was carried out. Spasm of arterioles, the marginal state of leukocytes and the desquamation of endotheliocytes into the lumen of a vessel, the stasis of erythrocytes in capillaries were revealed. The endothelial cells of capillaries had signs of increased transport of substances through the vessel walls: pinocytosis, fenestration, loosening of basal membranes. It was observed that capillaries are filled with shaped blood elements, on the luminal surface of endotheliocytes nuclei are protruded and the cytoplasm outgrowth into the lumen of the vessel is formed. At the same time, glucose oxidation accelerated both in the Krebs cycle and along the glycolytic pathway in the endotheliocytes of the vessels of the microcirculatory bed, indicating that the energy was supplied to the cells at a higher level. Disturbances of microcirculation were accompanied by focal destructive and inflammatory changes in the parenchyma of the organ.

scholarly journals Zika virus replication in glioblastoma cells: electron microscopic tomography shows 3D arrangement of endoplasmic reticulum, replication organelles, and viral ribonucleoproteins

2021 ◽  
Author(s):  
Johannes Wieland ◽  
Stefan Frey ◽  
Ulrich Rupp ◽  
Sandra Essbauer ◽  
Rüdiger Groß ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Line ◽  
Zika Virus ◽  
Structural Changes ◽  
Electron Tomography ◽  
Glioblastoma Cells ◽  
Electron Microscopic ◽  
N Protein ◽  
Ribonucleoprotein Complexes ◽  
Infected Cells

AbstractStructural changes of two patient-derived glioblastoma cell lines after Zika virus infection were investigated using scanning transmission electron tomography on high-pressure-frozen, freeze-substituted samples. In Zika-virus-infected cells, Golgi structures were barely visible under an electron microscope, and viral factories appeared. The cytosol outside of the viral factories resembled the cytosol of uninfected cells. The viral factories contained largely deranged endoplasmic reticulum (ER), filled with many so-called replication organelles consisting of a luminal vesicle surrounded by the ER membrane. Viral capsids were observed in the vicinity of the replication organelles (cell line #12537 GB) or in ER cisternae at large distance from the replication organelles (cell line #15747 GB). Near the replication organelles, we observed many about 100-nm-long filaments that may represent viral ribonucleoprotein complexes (RNPs), which consist of the RNA genome and N protein oligomers. In addition, we compared Zika-virus-infected cells with cells infected with a phlebovirus (sandfly fever Turkey virus). Zika virions are formed in the ER, whereas phlebovirus virions are assembled in the Golgi apparatus. Our findings will help to understand the replication cycle in the virus factories and the building of the replication organelles in glioblastoma cells.

Ultrastructural Changes in Euglena After Ultraviolet Irradiation

1973 ◽  
Vol 13 (3) ◽  
pp. 799-809
Author(s):  
A. MICHAELS ◽  
A. GIBOR
Keyword(s):  
Ultraviolet Light ◽  
Ultraviolet Irradiation ◽  
Euglena Gracilis ◽  
Structural Changes ◽  
Ultrastructural Changes ◽  
Electron Microscopic ◽  
Bleaching Process ◽  
In Cells

The structural changes associated with the ultraviolet-induced bleaching of light-grown cells of Euglena gracilis were investigated. Our light- and electron-microscopic observations of the bleaching process indicate that there is a continuity of plastid structure in cells 5 generations after receiving a bleaching dose of ultraviolet light. There seems to be a continuous dilution of the plastid thylakoids and a decrease in plastid size in the bleaching cells. There also seems to be a change in the position of the plastids in relation to the mitochondria in the bleaching cells. The plastids and possibly the mitochondria are the only organelles which are affected by the ultraviolet irradiation. The continuity of plastids in bleaching cells of Euglena is discussed in relation to the proposed effect of the ultraviolet light.

scholarly journals Beta3-Tubulin Is Critical for Microtubule Dynamics, Cell Cycle Regulation, and Spontaneous Release of Microvesicles in Human Malignant Melanoma Cells (A375)

2020 ◽  
Vol 21 (5) ◽  
pp. 1656
Author(s):  
Mohammed O. Altonsy ◽  
Anutosh Ganguly ◽  
Matthias Amrein ◽  
Philip Surmanowicz ◽  
Shu Shun Li ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Malignant Melanoma ◽  
Structural Changes ◽  
Melanoma Cells ◽  
Neoplastic Cell ◽  
Primary Component ◽  
Cellular Growth ◽  
Class Iii ◽  
M Cell ◽  
Human Malignant Melanoma

Microtubules (MTs), microfilaments, and intermediate filaments, the main constituents of the cytoskeleton, undergo continuous structural changes (metamorphosis), which are central to cellular growth, division, and release of microvesicles (MVs). Altered MTs dynamics, uncontrolled proliferation, and increased production of MVs are hallmarks of carcinogenesis. Class III beta-tubulin (β3-tubulin), one of seven β-tubulin isotypes, is a primary component of MT, which correlates with enhanced neoplastic cell survival, metastasis and resistance to chemotherapy. We studied the effects of β3-tubulin gene silencing on MTs dynamics, cell cycle, and MVs release in human malignant melanoma cells (A375). The knockdown of β3-tubulin induced G2/M cell cycle arrest, impaired MTs dynamics, and reduced spontaneous MVs release. Additional studies are therefore required to elucidate the pathophysiologic and therapeutic role of β3-tubulin in melanoma.

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