Actin Cytoskeleton ; Electromagnetic Fields

Seven fibrovascular diabetic preretinal membranes were examined with lightmicroscophic immunohistochemical stain and electron-microscopy to evaluate the possibility of pericytes to be involved in membrane contraction. Pericytes were positively stained with anti-actin antibody together with some stromal cells thought to be myofibroblasts presumedly. On transmission electron microscopic study, pericytes were highly active with numerous cytoplasmic processes and contained abundant microfilaments considered as actin in their cytoplasm. Pericyte/endothelial cell ratio of vascular channels were increased in some actively proliferative portion of the membranes. Myofibroblasts that contain abundant cytoplasmic microfilaments were also demonstrated in the extravascular stroma of the membranes and were very similar to the pericytes morphologically. Although the evidence that the pericytes are related to the origin of the myofibroblasts could not be demonstrated, this study suggested that the pericytes may play important roles in development and contraction mechanism of fibrovascular diabetic preretinal membranes.
Actin Cytoskeleton ; Actins ; Cytoplasm ; Membranes* ; Myofibroblasts ; Pericytes* ; Stromal Cells

OBJECTIVETo explore the effects of cofilin on the actin cytoskeleton reorganization in osteoblasts induced by fluid shear stress.

METHODSFluid shear stress (1.2 Pa) was applied to osteoblasts for 0 (control group), 15, 30, 45, 60, 120 min in vitro. Cells were stained with fluorescein isothiocyanate (FITC)-phalloidin for fiber-actin, and confocal laser scanning microscope(CLSM) was used to observe the fluorescence of fiber-actin. Western blotting was used to detect the expression of the cofilin and the phospho-cofilin.

RESULTSActin filaments became organized into stress fibers that were thicker and more abundant than those in non-flowed cells. The fluorescence intensity (38.00 ± 6.88) of fiber-actin after 120 min (42.93 ± 6.41) loading it was 2.8 times as much as that in control group (15.41 ± 3.60, P < 0.05). Additionally, the level of phospho-cofilin protein was dramatically elevated after loading. Fluid shear stress induced an initial decrease of cofilin at 60 min. However, at 120 min cofilin (0.254 ± 0.026) increased to 1.5 times as much as that at 60 min (0.162 ± 0.004).

CONCLUSIONSThe results indicate that cofilin phosphorylation mediates fiber-actin reorganization in the osteoblasts induced by fluid shear stress.

Actin Cytoskeleton ; ultrastructure ; Actin Depolymerizing Factors ; biosynthesis ; Humans ; Osteoblasts ; ultrastructure ; Phosphorylation ; Stress, Mechanical

The Kingdom fungus has a unique structure and organization. Recent advances in electron microscopy and use of specific cytochemical technique enable the ultrastructures to be visualized. The hypha is a tube-like structure with a rigid wall, containing a moving slug of protoplasm. Hypha grows only at the tapered apical tip region, which is called extension zone. Extreme tip area has apical vesicle cluster which is responsible for tip growth. Unique fungal structure, Spitzenk rper, is thought to be a central region of the apical vesicle cluster. Most hyphal structures except the species belong to Zygomycetes have septa. But the septum is not completely blocked and it has different types of opening pores. The simple septal pores with Woronin bodies, which are found in Ascomycetes and Deuteromycetes, can be plugged in two different mechanisms. During normal differentiation the pores become occluded by a gradual deposition of plugged material. Loss of cytoplasm from damaged hyphae can be reduced and blocked by the rapid occlusion of septal pores by Woronin bodies or hexagonal crystal bodies. Septal sealing in Basidiomycetes which have dolipore septum is made by the rapid formation of electron-dense pore plugs. The shape of the fungal cell is the shape of fungal wall. Fungal walls appear to be composed of layers, which are thought to merge into one another to form one structure. The cytoskeleton consists of microtubules and microfilaments with motor proteins, and they seems to act together in the fungal cells.
Actin Cytoskeleton ; Ascomycota ; Basidiomycota ; Cytoplasm ; Cytoskeleton ; Fungal Structures ; Fungi ; Gastropoda ; Hyphae ; Microscopy, Electron ; Microtubules ; Mitosporic Fungi

OBJECTIVE: The purpose of this study was to evaluate the effect of Cytochalasin B (CCB) on the cytoskeletal stability of mouse oocyte frozen by vitrification. METHODS: Mouse oocytes retrieved from cycle stimulated by PMSG and hCG were treated by CCB and then vitrified in EFS-30. These oocytes were placed onto an EM grid and submerged immediately in liquid nitrogen. Thawing of the oocytes was carried out at room temperature for 5 seconds, then the EM grid was placed into 0.75 M, 0.5 M and 0.25 M sucrose at 37degress C for 3 minutes, each. These oocytes were fixed in 4% formaldehyde for an hour and then washed in PPB for 15 minutes 3 times, then incubated in PPB containing anti-tubulin monoclonal antibody at 4degress C overnight. And then, the oocytes were incubated with FITC-conjugated anti-mouse IgG and propidium iodide (PI) for 45 minutes. Pattern of microtubules and microfilaments of oocytes were evaluated with a confocal microscope. RESULTS: The rate of oocytes containing normal microtubules and microfilaments was significantly decreased after vitrification. The rate of oocyte containing normal microtubules in CCB treated group was higher than those in non-treated group (53.7% vs. 48.9%), but the difference was not significant. The rate of oocyte containing normal microfilaments in CCB treated group was significantly higher than those in non-treated group (64.5% vs. 38.3%, p<0.05).CONCLUSION: Microfilaments stability could be improved by CCB treatment prior to vitrification. It is suggested that CCB treatment prior to vitrification improve stability of cytoskeleton and then increase success rate in IVF-ET program using vitrification and thawing oocyte.
Actin Cytoskeleton ; Animals ; Cytochalasin B* ; Cytoskeleton ; Formaldehyde ; Immunoglobulin G ; Mice* ; Microtubules ; Nitrogen ; Oocytes* ; Propidium ; Sucrose ; Vitrification*

OBJECTIVE: The purpose of this study was to evaluate the effect of Cytochalasin B (CCB) on the cytoskeletal stability of mouse oocyte frozen by vitrification. METHODS: Mouse oocytes retrieved from cycle stimulated by PMSG and hCG were treated by CCB and then vitrified in EFS-30. These oocytes were placed onto an EM grid and submerged immediately in liquid nitrogen. Thawing of the oocytes was carried out at room temperature for 5 seconds, then the EM grid was placed into 0.75 M, 0.5 M and 0.25 M sucrose at 37degress C for 3 minutes, each. These oocytes were fixed in 4% formaldehyde for an hour and then washed in PPB for 15 minutes 3 times, then incubated in PPB containing anti-tubulin monoclonal antibody at 4degress C overnight. And then, the oocytes were incubated with FITC-conjugated anti-mouse IgG and propidium iodide (PI) for 45 minutes. Pattern of microtubules and microfilaments of oocytes were evaluated with a confocal microscope. RESULTS: The rate of oocytes containing normal microtubules and microfilaments was significantly decreased after vitrification. The rate of oocyte containing normal microtubules in CCB treated group was higher than those in non-treated group (53.7% vs. 48.9%), but the difference was not significant. The rate of oocyte containing normal microfilaments in CCB treated group was significantly higher than those in non-treated group (64.5% vs. 38.3%, p<0.05).CONCLUSION: Microfilaments stability could be improved by CCB treatment prior to vitrification. It is suggested that CCB treatment prior to vitrification improve stability of cytoskeleton and then increase success rate in IVF-ET program using vitrification and thawing oocyte.
Actin Cytoskeleton ; Animals ; Cytochalasin B* ; Cytoskeleton ; Formaldehyde ; Immunoglobulin G ; Mice* ; Microtubules ; Nitrogen ; Oocytes* ; Propidium ; Sucrose ; Vitrification*

OBJECTIVETo investigate the relationship between c-fos gene and filamentous actin (F-actin) in MG-63 osteoblasts under cyclic tensile stress.

METHODSMG-63 osteoblasts were subjected to cyclic tensile stress (0.5 Hz, 2 000 microstrain) for 3, 6, and 12 h. The changes of c-fos gene were investigated by fluorescent quantitation polymerase chain reaction. Then the best loading time group was screened as the experimental group compared with 0 h group. The changes of F-actin and c-fos were investigated with or without cytochalasin D treatment.

RESULTSCyclic tensile stress induced high expression of c-fos mRNA, and peaked at 3 h. After loading, F-actin had a structure reorganization, but had no change in expression. After cytochalasin D treatment, the formation of stress fibers and the fluorescence intensity of F-actin cytoskeleton significantly reduced, meanwhile the c-fos mRNA expression was inhibited.

CONCLUSIONAfter loading, there is only structure reorganization for F-actin, and the expression has not any change. That means the remodeling F-actin is the existing one. F-actin reorganization is an important part in c-fos gene expression induced by stress.

Actin Cytoskeleton ; Actins ; Cytochalasin D ; Cytoskeleton ; Genes, fos ; Humans ; Microtubules ; Osteoblasts ; RNA, Messenger ; Stress, Mechanical

UNLABELLEDOBJECTIVE To evaluate the effects of grooved, alkali- and heat-treated, acid-etched and TiO2 blasted surfaces of titanium substrates on F-actin cytoskeleton of osteoblasts in vitro.

METHODSOsteoblasts derived from fetal rat calvarial were cultured on 6 different commercially pure titanium discs-grooved(G), sandblasted (SB), sand-blasted and acid-etching (SLA) surfaces and alkali- and heat-treated (AH1, AH2, AH3) surfaces. For F-actin cytoskeleton measurement, osteoblasts whose filamentous actin was stained with phalloidin-TRITC were cultured for 1, 2, 4, 12 h, evaluated by CLSM observation.

RESULTSOsteoblasts attached to the different types of surfaces after 1 hour culture were similar. The actin cytoskeleton formed a ring of cortical filaments around the nucleus after 1 hour on SB, AH2, AH3, SLA surfaces. Actin filaments condensed along edges of pits. The actin filaments of seeded cells were spread after 2 h. The actin filaments on G formed bundles around the nucleus. The filaments began to parallel to the grooves. On AH1, the fibres formed a ring of cortical filaments around the nucleus with some cytoplasmic fibres radially oriented. On AH2, AH3, SB, the fibres orignised in a cytoplasmic meshwork with fibres which terminate at the ridge of depressions. The cell were suspending itself over the depressed areas. Actin filaments on SB were distinct and well formed that were oriented paralled to one another and the long axis of cells. After 4 h, actin filaments appeared organised in a parallel to one another and the long axis of cells. After 12 h, the actin filaments on all surfaces were well spread and were oriented paralled to another and to the long axis of the cell. The filaments formed bundles which reached to holes or adhered to the ridge of raised points, suspending cells over depressed areas.

CONCLUSIONAfter 12 h, the actin filaments on all surfaces were well spread and were oriented parallel to another and to the long axis of the cell. It was concluded that F-actin cytoskeleton of osteoblasts were spread best on SB surfaces among all surfaces.

Actin Cytoskeleton ; Actins ; Animals ; Cytoskeleton ; Microtubules ; Osteoblasts ; Prostheses and Implants ; Rats ; Surface Properties ; Titanium

The cytoskeleton consists of 3 filamentous components: intermediate filaments, microtubules, and actin filaments. Actin filaments continuously assemble and disassemble far out of equilibrium to adapt cells in response to external stimuli. Actin filaments organization and dynamic are controlled by a multitude of actin-binding proteins including actin-bundling proteins. L-plastin, expressed abundantly in lymphocytes and monocytes, is an actin-bundling protein that roles in immune defense and in metastatic invasion of cancer cells. The actin-bundling activity of L-plastin is regulated not only by intracellular calcium concentration, but by phosphorylation of Ser5. The actin-bundling activity of L-pastin decreases by increased calcium concentration but is promoted by phosphorylation of Ser5. The morphology changes and motility of cells requires continuous remodeling of actin filaments which demands the sensitive nature of L-plastin to Ca2+-signal, phosphorylation of Ser5, and probably additional regulation. This review briefly describes the structure and regulation of L-plastin, and roles for L-plastin in cancer invasion and in macrophages.
Actin Cytoskeleton ; Calcium ; Cytoskeleton ; Intermediate Filaments ; Lymphocytes ; Macrophages* ; Microfilament Proteins ; Microtubules ; Monocytes ; Phosphorylation

Mice ; Animals ; Actins/metabolism* ; Actin Depolymerizing Factors/metabolism* ; TRPM Cation Channels ; Actin Cytoskeleton/metabolism* ; Nervous System/metabolism*