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  • 1
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    San Diego : Academic Press
    Call number: 04-ZELL:325
    Keywords: Centrosomes
    Pages: xii, 368 p. : ill.
    ISBN: 0123947707
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    04-ZELL:325 departmental collection or stack – please contact the library
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  • 2
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Fig. 1 Fibroblasts prepared by trypsin digestion from 1-d-old dystrophic (a) and normal (b] chicken muscle stained with antiserum to tubulin. In both cell types a similar cytoplasmic network of microtubules is clearly evident. Scale bar, 5 ??. To obtain dystrophic chicken cells, we used chickens ...
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0886-1544
    Keywords: circumferential microfilament bundles ; intercellular adhesion ; cytoskeleton ; junctional complex ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The junctional complexes in chick retinal pigment epithelial (RPE) cells in situ contain unusually large zonulae adhaerentes (ZAs) composed of subunits termed zonula adhaerens complexes (ZACs). To determine whether the properties of the ZAs differ between RPE cells which contain ZACs, and MDCK cells which lack ZACs, we investi-gated the effects of treatment with trypsin and/or low Ca2+ by transmission electron microscopy and staining for F-actin. Treatment of RPE cells for 1 h with trypsin alone has no apparent effect on the morphology of the ZA in either MDCK or RPE cells. In contrast to the ZAs in MDCK cells, which split after 3 min in low Ca2+, the ZAs in chick RPE cells stay intact even after 2 h, although the intermembrane discs, i.e., the extracellular components of the ZACs, are no longer visible. After 30 min of treatment with trypsin and low Ca2+, the ZAs split in both cell types. The CMBs start to contract, translocate toward the cell interior, and eventually disappear. This process continues even when the RPE cells are returned to normal medium. New ZAs, composed of ZACs, form between RPE cells 3 h after return to normal medium. These findings suggest that the ZACs in the ZAs of RPE cells are not directly responsible for the increase in resistance to low Ca2+. They also show that the ZA-junctions in RPE cells are not only structurally different from those previously examined, but also behave differently in response to experimental manipulation.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0878
    Keywords: Vinculin ; Spectrin ; Actin ; Epithelial sheet ; Immunofluorescence ; Chicken
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the differentiated pigmented epithelial cells of the retina (RPE) of chick embryos cytoskeletal proteins are found in polygonal rings located in the cell cortex. Within the cortical rings of the RPE cells vinculin and spectrin occupy a characteristic position closest to the plasma membrane; actin is found farther away, while tropomyosin and myosin are located farthest from the plasma membrane. The differences in the distribution of these proteins might reflect the functional specialization of different parts of the cortical ring required to develop and transmit tension from individual cells throughout the entire epithelial sheet.
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  • 5
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Morphological aspects of centriole replication as displayed in tracheal epithelial cells of 15 to 19-day-old chick embryos during ciliogenesis were examined by electron microscopy. It was found that centriole replication and development take place in a finely fibrous region around the two mature centrioles of the diplosome. Procentrioles in early stages of development are observed in clusters. The core of each cluster is occupied by one or more cylindrical structures which gradually disappear as the procentrioles mature. Some of the procentriolar clusters are attached directly to the walls of the diplosomal centrioles by the cylindrical cores. This observation suggests that all of the clusters may form initially in close association with the diplosomal centrioles. The earliest recognizable procentrioles are short, cylindrical structures that have no microtubules. Later microtubules appear, first as singlets, then doublets and finally as triplets. The singlet becomes the innermost microtubule of the triplet. Following the assembly of the nine triplets, the procentrioles separate from the clusters, elongate to their mature length and acquire rootlets, ciliary vesicles and cilia. The observation that all the procentrioles in each cell are in the same stage of development indicates that all the centrioles or presumptive basal bodies required by this cell are produced at the same time.
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  • 6
    ISSN: 1432-0878
    Keywords: Aorta ; Endothelium ; Centriole ; Organ culture ; Porcine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The distribution of centrosomes in porcine vascular endothelial cells of the thoracic aorta maintained in organ culture was determined in en face preparations using immunofluorescence. Rectangular pieces of aorta that had the distal half (with respect to the heart) of their endothelial surface gently denuded with a scalpel blade and pieces with intact endothelium were cultured for up to 96 h. At time 0, centrosomes were found to be preferentially oriented toward the heart, both in the cells of intact monolayers and in cells at the wound edge. This distribution was maintained in the intact monolayers for at least 24 h, but by 72 h the number of centrosomes in the center of the cells exceeded the number oriented toward the heart as the cells changed from a fusiform to a polygonal shape. The centrosomes of most endothelial cells at the wound edge began to redistribute themselves within the first 24 h in culture, moving from a position toward the heart to a position either in the center of the cell or away from the heart. By 72 h, the majority of centrosomes in endothelial cells at the wound edge were oriented away from the heart toward the denuded region. It is concluded that the centrosomes in the endothelial cells maintained in organ culture respond to injury in a manner similar to those grown in monolayer cell culture except that the reorientation of centrosomes occurs more slowly.
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  • 7
    ISSN: 1432-0878
    Keywords: Retina ; Pigment epithelium ; Cytoskeleton ; En face preparations ; Microfilaments ; Microfilament-associated proteins ; Chick embryos
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Gelatin-coated slides were used to obtain en face preparations of retinal pigment epithelium (RPE) from 6-to 21-day-old chick embryos in order to study the distribution of F-actin in microfilaments (MF) and the MF-associated proteins, myosin, tropomyosin,α-actinin and vinculin in situ at different stages of development by fluorescence microscopy. The epithelial sheets were fixed in formaldehyde and then extracted in a solution containing 0.1% Triton X-100. NBD-Phallacidin was used to visualize the F-actin in MF, and antisera against myosin, tropomyosin,α-actinin and vinculin were used to determine the distribution of these four MF-associated proteins. F-actin, myosin, tropomyosin,α-actinin and vinculin were present in cortical rings around the apical ends of the RPE cells throughout this period of development. Of these proteins, only F-actin was identified in the apical processes of RPE cells. The increase in the amount of F-actin could be followed as the length and the number of apical processes increased with age and maturation of RPE cells. F-actin was first detected in numerous short apical processes on the surface of each RPE cell on day 12. From day 12 to day 17, they were at an intermediate stage of elongation and from day 17 onward all of the RPE cells had long F-actin-containing apical processes. These results indicate that the F-actin-containing MF assemble much later in the apical processes than in the cortical rings. Also the cortical rings and apical processes of RPE cells resemble those in absorptive intestinal cells in that the cortical rings in both cell types contain MF associated with myosin, tropomyosin,α-actinin and vinculin while the MF in the apical processes and microvilli lack these MF associated proteins, and both of these structures lack talin. In addition to apical processes and cortical rings, stained fibers were also observed at a level below the cortical rings. The simple and highly reproducible en face method described is useful for determining changes in the organization of cytoskeletal components and other macromolecules in RPE cells and other epithelial cells in situ.
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  • 8
    ISSN: 1432-0878
    Keywords: Adherens-type junction ; Development ; Microfilaments ; Retinal pigment epithelium ; Chick
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Retinal pigment epithelial cells from chicks at various stages of development were examined by transmission electron microscopy to determine how the adult form of the zonula adhaerens, composed of subunits termed zonula adhaerens complexes, is acquired. During early stages of development, between embryonic day 4 and embryonic day 7, the intermembrane discs of zonula adhaerens complexes appear to be formed from material already present between the junctional membranes of the zonulae adhaerentes. In contrast, the cytoplasmic plaque material of the zonulae adhaerentes is difficult to detect before hatching; it is seen as a dense band along the junctional membranes at hatching and as individual subunits in register with the intermembrane discs in adult retinal pigment epithelial cells. After embryonic day 16, when the zonulae adhaerentes increase dramatically in size, single zonula adhaerens complexes are also present basal to the zonulae adhaerentes along the lateral cell membrane. This suggests that, during later stages of development, the junctions grow in size and/or turn over by the addition of pre-assembled zonula adhaerens complexes.
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  • 9
    ISSN: 1432-0878
    Keywords: Key words Endothelial cells ; Metastasis ; Actin filaments ; Cell ; cell interactions ; Tumor necrosis factor ; Confocal microscopy ; Man
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  An in vitro system has been established to study the migration of human melanoma cells through a monolayer of endothelial cells. Endothelial cells were cultured to confluence on Matrigel before the seeding of melanoma cells. Laser scanning confocal microscopy showed that, prior to migration, melanoma cells appeared round and showed cortical F-actin staining. The initial stage of transmigration was characterized by numerous membrane blebs protruding from basolateral surfaces of the melanoma cells, and contact regions showed an abundance of filaments arising in the underlying endothelial cells. Later, pseudopods from the melanoma cells inserted into contact regions between endothelial cells. Eventually, the melanoma cells intercalated with the endothelial cells. At this stage, many endothelial filament bundles terminated at contacts between the endothelial cells and the transmigrating melanoma cell, suggesting active interactions between the two cell types. Upon contact with the Matrigel, melanoma cells began to spread beneath the endothelium, displaying a fibroblastic morphology with prominent stress fibers. To reestablish the monolayer, adjacent endothelial cells extended processes over the melanoma cell. Tumor necrosis factor α did not affect the transmigration of melanoma cells from cell lines isolated from several stages of metastasis. However, tumor necrosis factor did promote the transmigration of melanoma cells derived from a non-metastatic lesion. These results thus define cell attachment and cell penetration of the monolayer as two distinct steps in transmigration and suggest that tumor necrosis factor may enhance the metastatic potential of tumor cells.
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  • 10
    ISSN: 1546-1718
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] Isolated human microphthalmia/anophthalmia, a cause of congenital blindness, is a clinically and genetically heterogeneous developmental disorder characterized by a small eye and other ocular abnormalities. Three microphthalmia/anophthalmia loci have been identified, and two others have been ...
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