Central root cap cells are depleted of endoplasmic microtubules and actin microfilament bundles: implications for their role as gravity-sensing statocytes

PROTOPLASMA ◽  
1997 ◽  
Vol 196 (3-4) ◽  
pp. 212-223 ◽  
Author(s):  
F. Balu?ka ◽  
Alessandra Kreibaum ◽  
S. Vitha ◽  
Jill S. Parker ◽  
P. W. Barlow ◽  
...  
Keyword(s):  
Root Cap ◽  
Actin Microfilament ◽  
Microfilament Bundles

HeLa cells form focal contacts that are not fibronectin dependent

1984 ◽  
Vol 66 (1) ◽  
pp. 133-145
Author(s):  
J. Morgan ◽  
D. Garrod
Keyword(s):  
Hela Cell ◽  
Hela Cells ◽  
Immunoglobulin G ◽  
Actin Microfilament ◽  
Focal Contacts ◽  
Microfilament Bundles ◽  
High Concentrations ◽  
The Relationship ◽  
Cells Cultured

HeLa cells cultured on glass substrata produce numerous prominent focal contacts, which reside at the termini of actin microfilament bundles. However, very few of the cells stain for fibronectin with specific anti-fibronectin antibody. Moreover, the cells form focal contacts in fibronectin-depleted medium, in the presence of high concentrations of anti-fibronectin immunoglobulin G and in the presence of monensin. No fibronectin synthesis can be detected by [35S]methionine-labelling and immunoprecipitation. The possibility that HeLa cell focal contacts are independent of fibronectin in their formation is discussed in relation to the controversy about the relationship between fibronectin and focal contacts.

scholarly journals The reorganization of microfilaments, centrosomes, and microtubules during in vitro small wound reendothelialization.

1988 ◽  
Vol 107 (5) ◽  
pp. 1777-1783 ◽  
Author(s):  
M K Wong ◽  
A I Gotlieb
Keyword(s):  
Cell Spreading ◽  
Time Lapse ◽  
Repair Process ◽  
Specific Sequence ◽  
Actin Microfilament ◽  
Wound Model ◽  
Microfilament Bundles ◽  
Endothelial Integrity ◽  
Made In

The repair of small endothelial wounds is an important process by which endothelial cells maintain endothelial integrity. An in vitro wound model system was used in which precise wounds were made in a confluent endothelial monolayer. The repair process was observed by time-lapse cinemicrophotography. Using fluorescence and immunofluorescence microscopy, the cellular morphological events were correlated with the localization and distribution of actin microfilament bundles and vinculin plaques, and centrosomes and their associated microtubules. Single to four-cell wounds underwent closure by cell spreading while wounds seven to nine cells in size closed by initially spreading which was then followed at approximately 1 h after wounding by cell migration. These two processes showed different cytoskeletal patterns. Cell spreading occurred independent of centrosome location. However, centrosome redistribution to the front of the cell occurred as the cells began to elongate and migrate. While the peripheral actin microfilament bundles (i.e., the dense peripheral band) remained intact during cell spreading, they broke down during migration and were associated with a reduction in peripheral vinculin plaque staining. Thus, the major events characterizing the closure of endothelial wounds were precise in nature, followed a specific sequence, and were associated with specific cytoskeletal patterns which most likely were important in maintaining directionality of migration and reducing the adhesion of the cells to their neighbors within the monolayer.

Cylindrical Substratum Induces Different Patterns of Actin Microfilament Bundles in Nontransformed and in ras-Transformed Epitheliocytes

1996 ◽  
Vol 229 (1) ◽  
pp. 159-165 ◽  
Author(s):  
Elina M. Levina ◽  
Lidia V. Domnina ◽  
Yuri A. Rovensky ◽  
Jury M. Vasiliev
Keyword(s):  
Actin Microfilament ◽  
Microfilament Bundles

scholarly journals The Endothelial Cytoskeleton: Organization in Normal and Regenerating Endothelium*

1990 ◽  
Vol 18 (4a) ◽  
pp. 603-617 ◽  
Author(s):  
Avrum I. Gotlieb
Keyword(s):  
Shear Stress ◽  
Structural Integrity ◽  
Phorbol Esters ◽  
Actin Microfilaments ◽  
Actin Microfilament ◽  
Cytoskeleton Organization ◽  
Cell Locomotion ◽  
Microfilament Bundles ◽  
External Stimuli ◽  
Hemodynamic Shear Stress

The components of the endothelial cell cytoskeleton that have been shown to be important in maintaining endothelial structural integrity and in regulating endothelial repair include F-actin microfilament bundles, including stress fibers, and microtubules, and centrosomes. Endothelial cells contain peripheral and central actin microfilaments. The dense peripheral band (DPB) consists of peripheral actin microfilament bundles which are associated with vinculin adhesion plaques and are most prominent in low or no hemodynamic shear stress conditions. The central microfilaments are very prominent in areas of elevated hemodynamic shear stress. There is a redistribution of actin microfilaments characterized by a decrease of peripheral actin and an increase in central microfilaments under a variety of conditions, including exposure to thrombin, phorbol-esters, and hemodynamic shear stress. During reendothelialization, there is a sequential series of cytoskeletal changes. The DPB remains intact during the rapid lamellipodia mediated repair of very small wounds except at the base of the lamellipodia where it is splayed. The DPB is reduced or absent when cell locomotion occurs to repair a wound. In addition, when cell locomotion is required, the centrosome, in the presence of intact microtubules, redistributes to the front of the cell to establish cell polarity and acts as a modulator of the directionality of migration. This occurs prior to the loss of the DPB but does not occur in very small wounds that close without migration. Thus, the cytoskeleton is a dynamic intracellular system which regulates endothelial integrity and repair and is modulated by external stimuli that are present at the vessel wall-blood interface.

Morphogenetic response of cultured normal and transformed fibroblasts, and epitheliocytes, to a cylindrical substratum surface. Possible role for the actin filament bundle pattern

1994 ◽  
Vol 107 (5) ◽  
pp. 1255-1263 ◽  
Author(s):  
YuA Rovensky ◽  
V.I. Samoilov
Keyword(s):  
Mouse Embryo ◽  
Cultured Cells ◽  
Cell Types ◽  
Actin Bundles ◽  
Actin Microfilament ◽  
Mouse Embryo Fibroblasts ◽  
Transformed Fibroblasts ◽  
Microfilament Bundles ◽  
Embryo Fibroblasts ◽  
High Degree

Morphometric characteristics such as cell area, dispersion, elongation and orientation were studied in normal and transformed fibroblasts, and in epitheliocytes cultured on flat or cylindrical substrata. Cylindrical surfaces with a high degree of curvature (12-13 or 25 microns radii) were shown to affect cell size, shape and alignment. The reaction of the cells to the curvature of cylindrical substrata was different in various cell types studied and depended on the pattern of actin microfilament bundles. The cells containing pronounced straight actin bundles (mouse embryo fibroblasts at the polarization stage of spreading, single spread cells of the ‘normal’ epithelial FBT line or the fully transformed epithelial IAR 6–1 line) were relatively resistant to bending around a cylindrical substratum, and became elongated and oriented along the cylinder. Cells with circular actin bundles as the predominant pattern (mouse embryo fibroblasts at the radial stage of spreading, single spread cells of ‘normal’ epithelial IAR 20 line) and cells with insufficient or no actin bundles (transformed fibroblastic L line) were prone to bending around a cylinder with much less pronounced elongation and orientation along its axis. The data obtained indicate that the reaction of cultured cells to the geometry of the substratum surface and, in particular, to a cylindrical surface is determined not only by the presence or absence of actin microfilament bundles but by their pattern in the cell.

Changes in actin microfilament arrays in developing pea root nodule cells

2001 ◽  
Vol 79 (7) ◽  
pp. 767-776 ◽  
Author(s):  
A L Davidson ◽  
W Newcomb
Keyword(s):  
Rhizobium Leguminosarum ◽  
Root Nodule ◽  
Infection Process ◽  
Host Cells ◽  
Actin Microfilaments ◽  
Symbiotic Associations ◽  
Actin Microfilament ◽  
Pea Root ◽  
Microfilament Bundles ◽  
Infected Cells

Various microorganisms that form symbiotic associations with plant roots alter the cytoskeleton of host cells. The objective of this study was to determine the organization of actin microfilaments in developing Pisum sativum L. (pea) root nodule cells at various stages after infection by Rhizobium leguminosarum bv. viciae. Fluorescently labelled microfilaments in uninfected pea root nodule cells occur in association with the nucleus, along cytoplasmic strands, and as long microfilament bundles randomly organized in the cortex of the cell. These actin arrays are also present in recently infected cells that have been invaded by an infection thread and contain a small number of bacteroids. In addition, the recently infected cells contain diffuse cytoplasmic actin, long actin microfilament bundles near the vacuole, and a nuclear-associated network of microfilament bundles. In older infected cells, the predominant array is a network of cytoplasmic microfilaments that are wavy and extend in multiple directions within the cell; the network is equally abundant in all regions of the cytoplasm and may interact with the bacteroids and organelles. Thus, actin microfilaments reorganize during the pea root nodule infection process to form distinct arrays whose organization depends on the stage of infection.Key words: nodule, actin microfilaments, Rhizobium, pea, symbiosis.

Localization of acid phosphatases in root cap of rice plant

1991 ◽  
Vol 49 ◽  
pp. 224-225
Author(s):  
Y. R. Chen ◽  
Y. F. Huang ◽  
W. S. Chen
Keyword(s):  
Rice Plant ◽  
Developmental Stages ◽  
Uranyl Acetate ◽  
Root Cap ◽  
Plant Tissues ◽  
Acid Phosphatases ◽  
Root Tips ◽  
Buffer Solution ◽  
Cacodylate Buffer ◽  
Ethanol Series

Acid phosphatases are widely distributed in different tisssues of various plants. Studies on subcellular localization of acid phosphatases show they might be present in cell wall, plasma lemma, mitochondria, plastid, vacuole and nucleus. However, their localization in rice cell varies with developmental stages of cells and plant tissues. In present study, acid phosphatases occurring in root cap are examined.Sliced root tips of ten-day-old rice(Oryza sativa) seedlings were fixed in 0.1M cacodylate buffer containing 2.5% glutaraldehyde for 2h, washed overnight in same buffer solution, incubated in Gomori's solution at 37° C for 90min, post-fixed in OsO4, dehydrated in ethanol series and finally embeded in Spurr's resin. Sections were doubly stained with uranyl acetate and lead citrate, and observed under Hitachi H-600 at 75 KV.

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