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  • 1
    Electronic Resource
    Electronic Resource
    Cytoskeletal organization of migrating retinal pigment epithelial cells during wound healing in organ culture (1989)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 13 (1989), S. 83-93 
    Details
    ISSN: 0886-1544
    Keywords: retinal pigment epithelium ; cytoskeleton ; focal contacts ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Retinal pigment epithelial (RPE) cells maintained in organ culture on Bruch's membrane and the associated choroid spread and migrate into a linear wound along the exposed basal lamina. Changes in cell shape, in the organization of microfilaments, and in cell-cell and cell-substratum interactions during this time were examined by epifluorescence and transmission electron microscopy. In contrast to cuboidal stationary cells distant from the wound edge, which display well-developed apical circumferential microfilament bundles (CMBs) associated with zonulae adhaerentes junctions, the migrating RPE cells near the wound edge instead are flat, and, in addition to microfilament bundles near junctions between adjacent cells, display prominent stress fibers. Furthermore, monoclonal antibodies to vinculin labeled regions at the terminal ends of these stress fibers indicating that the RPE cells form focal contacts with the basal lamina at these sites. Electron microscopy of these regions of cell-substratum interaction confirmed the presence of microfilament bundles that terminate on the cell membrane. Folds present in the basal lamina near these sites suggest that tension is being generated by the microfilaments in the stress fibers as the migrating cells pull on the underlying basal lamina through these adhesion points.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970130203
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of trypsin and low Ca2+ on zonulae adhaerentes between chick retinal pigment epithelial cells in organ culture (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 46-58 
    Details
    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
    URL: http://dx.doi.org/10.1002/cm.970170107
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  • 3
    Electronic Resource
    Electronic Resource
    Reorganization of circumferential microfilament bundles in retinal epithelial cells during mitosis (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 133-141 
    Details
    ISSN: 0886-1544
    Keywords: contractile ring ; cytoskeleton ; cell division ; cytokinesis ; zonula adhaerens ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: To examine the behaviour of the apical circumferential microfilament bundles (CMBs) associated with the zonula adhaerens (ZA)-junctions during mitosis, retinal pigment epithelial cells were labelled for F-actin, and retinas were serially sectioned for TEM. The results show that the ZA-CMB-complex persists throughout all stages of mitosis. At metaphase, the cells round up, but stay joined apically to adjacent cells by ZA-junctions. At telophase, the cleavage furrow forms asymmetrically from the basal end progressively toward the apical end, where the daughter cells remain connected by an intercellular bridge (IB). As the cleavage furrow with the contractile ring (CR) approaches the CMB, the two microfilament (MF) systems are oriented perpendicularly to each other. At the level of the CMB, the MFs of the CR connect the opposite sides of the CMB and bisect it into two CMBs, one for each of the two daughter cells. Subsequently, the CR in the IB splits into two, one on either side of the midbody. The two daughter cells, having acquired a complete CMB of their own, do not become direct neighbours, since adjacent cells, which remain joined to the apical ZA-junction of the dividing cell, are observed in the cleavage furrow, where they meet and form a ZA-junction between themselves, just below the IB. Separation of the daughter cells without losing contact with neighbouring cells at the level of the apical ZA-junction thus maintains the integrity of the epithelial sheet during mitosis.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970170208
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  • 4
    Electronic Resource
    Electronic Resource
    Morphological changes in the zonula adhaerens during embryonic development of chick retinal pigment epithelial cells (1990)
    Springer
    Cell & tissue research 259 (1990), S. 455-461 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01740771
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  • 5
    Electronic Resource
    Electronic Resource
    Characterization of 57 kDa statin as a true marker for growth arrest in tissue by its disappearance from regenerating liver (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 158 (1994), S. 277-284 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Statin, a 57 kDa nuclear protein, is lost from quiescent fibroblasts in culture when they are induced to enter the cell cycle by feeding with growth factors, or by removal of contact inhibition. In order to investigate changes in statin expression during the transition from a quiescent to a cycling state in situ, we performed 70% partial hepatectomy on rats and analyzed the regenerating liver by immunofluorescence microscopy with antistatin monoclonal antibodies (S44 mAb), and by immunoblotting of liver proteins in cytoplasmic and enriched nuclear/cytoskeletal fractions. Western blot analysis showed that rat hepatocytes in situ contain a nuclear 57 kDa form of statin, as seen in cultured fibroblasts; however additional S44-immunoreactive polypeptides with molecular weights of 53 and 110 kDa are also present in both cytoplasmic and nuclear/cytoskeletal fractions. Immunofluo-rescence microscopy indicates that the proportion of S44-positive hepatocyte nuclei drops to ∼60% within 24 hours after hepatectomy, a time period when re-entry of hepatocytes into the cell cycle is first observed. On Western blots of hepatocyte nuclear/cytoskeletal proteins obtained 24 hours after hepatectomy, the 57 kDa form of statin is markedly reduced. These results suggest that, although in liver the S44 antibody recognizes three proteins (53 kDa, 57 kDa, and 110 kDa), the 57 kDa in intact liver, similar to cultured fibroblasts, is the only polypeptide recognized by the statin antibody that disappears when hepatocytes are induced to re-enter the cell cycle from a quiescent state. © 1994 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041580210
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  • 6
    Electronic Resource
    Electronic Resource
    The cleavage pattern in the leech Theromyzon tessulatum (Hirudinea, Glossiphoniidae) (1988)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 196 (1988), S. 217-252 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In order to evaluate the differences in the cleavage patterns of the glossiphoniid leeches Glossiphonia complanata and Theromyzon tessulatum, previously studied by Müller ('32) and Schmidt ('17, '41), the cleavage of Theromyzon tessulatum was reexamined. For the period of the first 29 hours of development embryos were observed, photographed, and serially sectioned for light microscopy at each developmental stage. The exact cell lineage until completion of teloblast formation is reported. Besides some other not previously reported features, we show that the mesoteloblast precursor cell in the glossiphoniid leeches, as probably in most Annelida, is not the cell 3D, but cell 4d formed by an additional division of cell 3D. The results further indicate that all glossiphoniid leeches likely share a common cleavage pattern, and that major differences between Glossiphonia complanata and Theromyzon tessulatum do not exist. A comparison between the cleavage patterns of some Oligochaeta and Hirudinea is made, and plesiomorphic characters in the cleavage of a clitellate ancestor species and their deviations in present day species are discussed.
    Additional Material: 32 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051960210
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