Effect of colcemid on the locomotory behaviour of fibroblasts

Development ◽  
1970 ◽  
Vol 24 (3) ◽  
pp. 625-640
Author(s):  
Ju. M. Vasiliev ◽  
I. M. Gelfand ◽  
L. V. Domnina ◽  
O. Y. Ivanova ◽  
S. G. Komm ◽  
...  
Keyword(s):  
Cell Surface ◽  
Electron Microscopic Examination ◽  
Mouse Fibroblast ◽  
Active State ◽  
Structural Basis ◽  
Fish Scale ◽  
Electron Microscopic ◽  
Locomotory Behaviour ◽  
Embryonic Fibroblast

Effects of metaphase inhibitors (colcemid, colchicine, vinblastine) on mouse and human embryonic, fibroblast-like cells growing on glass and on an oriented substrate (fish scale) were studied. All three inhibitors caused similar changes in the form of interphase cells and inhibited their directional locomotion. The effects of two inhibitors (colcemid and vinblastine) were found to be completely reversible. Microcinematographic studies have shown that the most conspicuous change of locomotory behaviour induced by colcemid was the disappearance of non-active stable parts of the cell edge; in normal cells only the leading part of the edge was actively moving, while in colcemid-treated cells all parts of the edge eventually became active. Activation of the whole edge made these cells unable to perform directional translocation. It is suggested that colcemid and other metaphase inhibitors prevent stabilization of the non-active state of the cell surface. The possible role of this suggested colcemid-sensitive stabilization mechanism in the normal locomotory behaviour of fibroblasts is discussed. Electron-microscopic examination has shown that microtubules disappeared from the cytoplasm of colcemid-treated, mouse, fibroblast-like cells. The formation of microtubules as the possible structural basis of the stabilization of the non-active state of the cell surface is discussed.

scholarly journals Mice Deficient in the Axonemal Protein Tektin-t Exhibit Male Infertility and Immotile-Cilium Syndrome Due to Impaired Inner Arm Dynein Function

2004 ◽  
Vol 24 (18) ◽  
pp. 7958-7964 ◽  
Author(s):  
Hiromitsu Tanaka ◽  
Naoko Iguchi ◽  
Yoshiro Toyama ◽  
Kouichi Kitamura ◽  
Tohru Takahashi ◽  
...  
Keyword(s):  
Physiological Role ◽  
Electron Microscopic Examination ◽  
Electron Microscopic ◽  
Vitro Fertilization ◽  
Homozygous Mutant ◽  
Causal Genes ◽  
And Function ◽  
Ciliary Dyskinesia

ABSTRACT The haploid germ cell-specific Tektin-t protein is a member of the Tektin family of proteins that form filaments in flagellar, ciliary, and axonemal microtubules. To investigate the physiological role of Tektin-t, we generated mice with a mutation in the tektin-t gene. The homozygous mutant males were infertile, while the females were fully fertile. Sperm morphology and function were abnormal, with frequent bending of the sperm flagella and marked defects in motility. In vitro fertilization assays showed that the defective spermatozoa were able to fertilize eggs. Electron microscopic examination showed that the dynein inner arm structure was disrupted in the sperm flagella of tektin-t-deficient mice. Furthermore, homozygous mutant mice had functionally defective tracheal cilia, as evidenced by altered dynein arm morphology. These results indicate that Tektin-t participates in dynein inner arm formation or attachment and that the loss of Tektin-t results in impaired motility of both flagella and cilia. Therefore, the tektin-t gene is one of the causal genes for immotile-cilium syndrome/primary ciliary dyskinesia.

Role of particle electrostatic charge in adhesion and ingestion in Dictyostelium discoideum amoeboid cells

1985 ◽  
Vol 79 (1) ◽  
pp. 327-342
Author(s):  
R. Hellio ◽  
A. Ryter
Keyword(s):  
Cell Surface ◽  
Dictyostelium Discoideum ◽  
Iron Hydroxide ◽  
Ingestion Rate ◽  
Polyglutamic Acid ◽  
Unknown Parameters ◽  
Electron Microscopic ◽  
Electrostatic Charges ◽  
Carboxylic Groups

The use of colloid iron hydroxide, Alcian Blue and enzymic treatments confirmed that the negative charges of Dictyostelium discoideum cell surface are mostly due to carboxylic groups. The role of electrostatic charges in adhesion and ingestion was determined by exposing cells to untreated latex beads, polylysine or polyglutamic-acid-coated beads, or carboxylated beads. This study showed that negatively charged beads presented a weaker adhesion strength than positively charged ones and that adhesion was strongest with untreated beads. This shows that hydrophobic forces are stronger than those induced by opposite electric charges between particle and cell surface. The ingestion rate was not directly related to adhesion because negatively charged beads presented the highest phagocytic rate, polylysine-coated beads had the lowest and neutral beads an intermediate one. The treatment of cells with polylysine or polyglutamic acid before neutral bead addition generally enhanced the ingestion rate. Electron microscopic observations made on polylysine-treated cells showed, however, that this stimulating effect was not due to the presence of the polymer on the cell surface but to a membrane clearance phenomenon occurring during polymer elimination. All these observations have led to the conclusion that the electric charges of the particle do not play a major role in D. discoideum phagocytic ability. Hydrophobic forces and probably other unknown parameters related to the cell surface properties are more important.

The role of electron microscopy in the diagnosis of tumours of the Head and neck

1992 ◽  
Vol 106 (5) ◽  
pp. 403-408
Author(s):  
C. Fisher ◽  
L. M. Flood ◽  
A. D. Ramsey
Keyword(s):  
Electron Microscopy ◽  
Head And Neck ◽  
Electron Microscopic Examination ◽  
Undifferentiated Carcinoma ◽  
Ultrastructural Examination ◽  
Head And Neck Tumours ◽  
Electron Microscopic ◽  
Diagnostic Significance ◽  
Diagnostic Benefit

AbstractA four-year study was undertaken to determine the value of electron microscopy in the diagnosis of head and neck tumours. During this period 80 samples were submitted for examination, of which 69 contained assessable tumour. Electron microscopy made a major contribution to the diagnosis in 25 cases (36 per cent). Areas in which ultrastructural examination was of diagnostic significance included the precise categorization of apparently undifferentiated carcinoma and the identification of melanomas. Little diagnostic benefit was gained from electron microscopic examination of thyroid, lymphoid or salivary gland neoplasms. The value of electron microscopy in relation to immunohistochemistry is discussed.

Scanning Electron Microscopic Examination of Nonbeating Cilia

1982 ◽  
Vol 91 (6) ◽  
pp. 612-614 ◽  
Author(s):  
James P. Dudley ◽  
Lance Eisner ◽  
James D. Cherry
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electron Microscopic Examination ◽  
Organ Cultures ◽  
Electron Microscopic ◽  
Scanning Electron Microscopic ◽  
Respiratory Membrane ◽  
Additional Role ◽  
Scanning Electron

When cilia stop beating, their role in moving mucus ceases, but it is uncertain if nonmotile cilia preserve their external architecture and are thus capable of maintaining an additional role of retarding microbial access to the cell. Cilia of chicken embryo tracheal organ cultures were observed until their activity stopped. When examined with scanning electron microscopy, ciliary axonemes did not appear to differ significantly from normally functioning cilia when observed at lower magnifications. Since their density can remain essentially unchanged, nonbeating cilia may still have a role in protecting respiratory membrane from toxic microorganisms.

scholarly journals Integrin activation takes shape

2002 ◽  
Vol 158 (5) ◽  
pp. 833-839 ◽  
Author(s):  
R.C. Liddington ◽  
M.H. Ginsberg
Keyword(s):  
Cell Surface ◽  
Ligand Binding ◽  
Cytoplasmic Domain ◽  
Structural Basis ◽  
Surface Adhesion ◽  
Integrin Activation ◽  
Adhesion Receptors ◽  
Ligand Activation ◽  
And Function

Integrins are cell surface adhesion receptors that are essential for the development and function of multicellular animals. Here we summarize recent findings on the regulation of integrin affinity for ligand (activation), one mechanism by which cells modulate integrin function. The focus is on the structural basis of integrin activation, the role of the cytoplasmic domain in integrin affinity regulation, and potential mechanisms by which activation signals are propagated from integrin cytoplasmic domains to the extracellular ligand-binding domain.

scholarly journals Immunohistochemical demonstration of Fc receptors of human lymph node cells using peroxidase-antiperoxidase (IgG).

1980 ◽  
Vol 28 (3) ◽  
pp. 271-275 ◽  
Author(s):  
G Itoh
Keyword(s):  
Lymph Node ◽  
Cell Surface ◽  
Microscopic Examination ◽  
Fc Receptors ◽  
Electron Microscopic Examination ◽  
Reaction Products ◽  
Electron Microscopic ◽  
Regional Lymph Nodes ◽  
Human Lymph Node ◽  
Lymph Node Cells

Human lymph node cells, prepared from regional lymph nodes excised from four patients with gastric cancer, were incubated with peroxidase-antiperoxidase (IgG) (PAPIgG). After being washed, they were reacted with diaminobenzidine tetrahydrochloride in the presence of H2O2. Light microscopic examination revealed that a certain proportion of lymph node cells (18.2-32.2%) were labeled on their cell surface with brown-colored reaction products and that the labeled cells were composed of small lymphocytes. Electron microscopic examination demonstrated electron-dense irregular-shaped aggregates of reaction products on the cell surface of lymphocytes. Characterization experiments confirmed that the immune complexes of PAPIgG bound specifically with Fc receptors. PAPIgG, therefore, can be used as a specific indicator for Fc receptor of human lymph node cells.

Integrin Activation

2001 ◽  
Vol 86 (07) ◽  
pp. 316-323 ◽  
Author(s):  
D. G. Woodside ◽  
S. Liu ◽  
M. H. Ginsberg
Keyword(s):  
Cell Adhesion ◽  
Cell Surface ◽  
Ligand Binding ◽  
Cellular Adhesion ◽  
Structural Basis ◽  
Surface Adhesion ◽  
Integrin Activation ◽  
Ligand Activation ◽  
Dependent Cell

SummaryIntegrins are cell surface adhesion receptors that participate in a variety of important processes throughout the vasculature. Here we summarize some recent findings on the regulation of integrin mediated cellular adhesion. Particular emphasis is placed on the regulation of integrin affinity for ligand (activation), although this is just one mechanism by which regulation of integrin-dependent cell adhesion can occur. Also discussed are recent observations on the structural basis of integrin activation, the role of the cytoplasmic domain in integrin affinity regulation, and potential mechanisms by which activation signals are propagated from integrin cytoplasmic domains to the extracellular ligand binding domain.

A study of specialized cells of the tracheal gills of Paragnetina media (Plecoptera)

1973 ◽  
Vol 51 (9) ◽  
pp. 983-986 ◽  
Author(s):  
N. N. Kapoor ◽  
K. Zachariah
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Microscopic Examination ◽  
External Environment ◽  
Electron Microscopic Examination ◽  
Active Surface ◽  
Electron Microscopic ◽  
Close Relationship ◽  
Paragnetina Media ◽  
Tracheal Gills

Light and electron microscopic examination of the gills of the plecopteran nymph Paragnetina media revealed a highly tracheated epithelium with many specialized cells. These cells show several features characteristic of the osmoregulatory tissue of other animals. In the cell, numerous mitochondria are lodged in elongated folds of the plasma membrane in such a way that they are brought into a very close relationship to an area of the cell surface. It is assumed that this arrangement provides metabolically active surface for the exchange of materials, absorption, or excretion. It is most likely that the gills can absorb salt from the water, and thus compensate for the loss of salt through the urine. The distinctive cuticular plaque which forms the interface of each cell with the external environment is featured and discussed too.

Actin-dependent light-induced translocation of mitochondria and ER cisternae in the photoreceptor cells of the locust Schistocerca gregaria

1995 ◽  
Vol 108 (6) ◽  
pp. 2273-2283 ◽  
Author(s):  
K. Sturmer ◽  
O. Baumann ◽  
B. Walz
Keyword(s):  
Actin Filaments ◽  
Cytochalasin B ◽  
Schistocerca Gregaria ◽  
Smooth Endoplasmic Reticulum ◽  
Close Association ◽  
Electron Microscopic Examination ◽  
Photoreceptor Cells ◽  
Electron Microscopic ◽  
Filament Bundles

Light-dependent changes in the positioning of organelles in photoreceptor cells of arthropods are a well-known phenomenon. In this study, we examine the role of the cytoskeleton in these light-dependent antagonistic movements. In dark-adapted photoreceptor cells of the locust Schistocerca gregaria, prominent sacs of smooth endoplasmic reticulum (ER) oppose the bases of the photoreceptive microvilli. Light stimulation causes a translocation of the ER elements towards the main cell body, and an aggregation of mitochondria adjacent to the microvilli. Immunofluorescence studies and electron-microscopic examination of chemically fixed or high-pressure-frozen, freeze-substituted specimens demonstrate a lack of microtubules in the submicrovillar region. However, numerous filament bundles are aligned in close association with mitochondria and ER elements, along the track of their movement. Fluorescent phallotoxins and monoclonal anti-actin antibodies label filament bundles in the submicrovillar region, indicating that they are composed of F-actin. Finally, depolymerization of the submicrovillar actin filaments by incubation with cytochalasin B results in a blockade of the movement of mitochondria and ER cisternae towards the rhabdom. These results suggest that the light-dependent translocation of both ER cisternae and mitochondria occurs along actin filaments.

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