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  • 1
    Electronic Resource
    Electronic Resource
    Phosphorylation of phospholamban correlates with relaxation of coronary artery induced by nitric oxide, adenosine, and prostacyclin in the pig (1998)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 70 (1998), S. 49-59 
    Details
    ISSN: 0730-2312
    Keywords: coronary artery ; NO/EDRF ; adenosine ; prostacyclin ; phospholamban ; myosin light chain ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The intracellular mechanisms underlying the action of the endogenous vasodilators such as NO/EDRF, adenosine, and prostacyclin acting through cGMP and cAMP, respectively, are not well understood. One important action of cyclic nucleotides in smooth muscle relaxation is to lower the cytosolic Ca2+ concentration by enhanced sequestration into the sarcoplasmic reticulum. The present study was undertaken to elucidate the potential role of phosphorylation of phospholamban, the regulator of sarcoplasmic reticulum Ca2+ pump, for the control of coronary vascular tone by NO/EDRF, adenosine, and prostacyclin. Phospholamban was identified in pig coronary artery preparations by immunofluorescence microscopy, Western blotting and in vitro phosphorylation. Segments of pig coronary artery, with either intact or denuded endothelium, were precontracted with prostaglandin F2α (PGF2α). In endothelium-denuded preparations 3-morpholinosydnonimine (SIN-1), 5′-N-ethylcarboxiamidoadenosine (NECA), and iloprost (ILO) caused both relaxation and phospholamban phosphorylation with the potency: SIN-1 〉 NECA 〉 ILO. The regulatory myosin light chain was significantly dephosphorylated only by SIN-1. In endothelium-intact pig coronary artery, L-NAME caused additional vasoconstriction and a decrease in phospholamban phosphorylation, while phosphorylation of myosin light chain remained unchanged. An inverse relationship between phospholamban phosphorylation and vessel tone was obtained. Our findings demonstrate significant phospholamban phosphorylation during coronary artery relaxation evoked by NO, prostacyclin, and adenosine receptor activation. Because of the close correlation between phosphorylation of phospholamban and vessel relaxation, we propose that phospholamban phosphorylation is an important mechanism by which endogenous vasodilators, especially endothelial NO/EDRF, control coronary vascular smooth muscle tone. J. Cell. Biochem. 70:49-59, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    The history of the germ cells in the viviparous teleost platypoecilus maculatus (1931)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 52 (1931), S. 115-153 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study is based upon a series of ontogenetic stages from just before coelom formation to maturity.Primordial germ ceils are first seen at the outer edge of the lateral mesoderm and are traced from there to a position in the genital analagen. Counts indicate that most of them succeed in reaching the genital anlagen, where they from definitive reproductive cells in both sexes.The evidence seems to show that there is some transformation of somatic cells into germ cells in the immature female, but that this transformation is not extensive. In the male the primordial germ cells are the sole source of the definitive elements.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1050520106
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  • 3
    Electronic Resource
    Electronic Resource
    Cytoplasmic bags: Containers for discarded paraflagellar membranes in spermiogenesis of graphosome lineatum (Pentatomidae, Hemiptera, Insecta) (1995)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 226 (1995), S. 141-148 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The process of cytoplasmic sloughing is described in spermiogenesis of a stink bug, Graphosoma lineatum, using transmission electron microscopy of ultrathin sections. Tails of young spermatids possess a wide cytoplasmic layer lateral to the axoneme and the nenbenkern derivatives. Membranous sheets, comprised of cisternae of endoplasmic reticulum with very narrow lumina, are arranged parallel to these organelles. More advanced spermatids show only a thin cytoplasmic layer largely devoid of membranes. At this stage, large evaginations of the flagellar membrane, termed cytoplasmic bags, are found in association with the spermatid tails. The most prominent elements within these bags are concentric layers of endoplasmic reticulum of the type previously found in spermatid tails. This relationship suggests that the cells rid themselves of cytoplasmic membranes throughout spermiogenesis via inclusion into cytoplasmic bags. Upon release from the nucleate cytoplasm, the cytoplasmic bags become more and more electron-dense and degenerate. © 1995 Wiley-Liss, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052260203
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  • 4
    Electronic Resource
    Electronic Resource
    Cytochalasin B-induced redistribution of cytokeratin filaments in PtK1 cells (1987)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 7 (1987), S. 347-360 
    Details
    ISSN: 0886-1544
    Keywords: cytochalasin ; actin ; microtubules ; immunofluorescence ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Indirect immunofluorescence demonstrated a dramatic reorganization of cytokeratin filaments produced by cytochalasin B (CB) treatment of PtK1 cells. Much of the normal cytokeratin network became arranged into a latticework consisting of bundles of cytokeratin filaments that radiated from, and interconnected, distinct foci, Electron microscopy showed foci to be dense granular regions through which bundles of cytokeratin filaments looped. Composition of the foci included actin, myosin, and alpha-actinin, as shown by labeling with rhodamine phalloidin or specific antisera. Simultaneous treatment with CB and colchicine was not required for lattice formation, but did produce more extensive development than did CB alone. In cells treated only with CB, the microtubule network remained intact, even in regions of extensive lattice formation. These results contrast sharply with those of Knapp et al (J. Cell Biol. 97:1788 [1983b]), who found lattice formation dependent upon simultaneous CB and colchicine treatment. Time-course and dose-response studies of CB treatment showed lattice formation to follow disruption of stress fibers and the concentration of actin into distinct patches that marked the location of lattice foci. Overall results suggest a structural association between microfilaments and cytokeratin filaments that produces the lattice pattern upon CB-induced disruption of stress fibers. Lattice formation was not limited to a specific cell-cycle stage, since G1, G2, and M cells displayed the lattice. Treatment of cells with dihydro-CB and experiments with enucleated cells showed that lattice formation was dependent upon neither the inhibition of sugar transport nor the nuclear extrusion effects of CB.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970070407
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  • 5
    Electronic Resource
    Electronic Resource
    Centripetal movement of homologs occurs at the onset of anaphase A in primary oocytes of Ephestia kuehniella Z. (Pyralidae, Lepidoptera) (1993)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 24 (1993), S. 200-204 
    Details
    ISSN: 0886-1544
    Keywords: metaphase ; anaphase ; spindle ; oogenesis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The transition from metaphase to anaphase was examined in primary oocytes of the Mediterranean mealmoth, Ephestia kuehniella. Isolated spindles were analysed using phase-contrast microscopy and antitubulin immunofluorescence. Metaphase I bivalents in female Lepidoptera contain material derived from the synaptonemal complexes, the elimination chromatin, which is located between the homologs. Upon the onset of anaphase I, the homologs detach from the elimination chromatin. The present observations revealed that prior to the start of anaphase A, the homologs move centripetally, i.e., toward the central spindle axis, while the elimination chromatin remains stationary. This type of movement is not directly comparable with conventional chromosome movements such as prometaphase congression, anaphase A, and anaphase B, since it occurs at right angles to the preferential orientation of the spindle MTs. A MT-based mechanism may nevertheless account for the centripetal shift of homologs in meiosis I of the moth: bundling of kinetochore MTs of different chromosomes could transfer the chromosomes toward the spindle axis. Since the homologs move along the poleward surfaces of the plate of elimination chromatin, a MT-independent force producer could exist as well at the interface between the chromosomes and the plate of elimination chromatin. © 1993 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970240307
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  • 6
    Electronic Resource
    Electronic Resource
    Behavior of C-shaped microtubule endings in the cell (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 17 (1990), S. 59-67 
    Details
    ISSN: 0886-1544
    Keywords: Polytoma papillatum ; Megaselia scalaris ; protofilament ; mitosis ; meiosis ; spindle ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The association of incomplete microtubule assemblies with either another incom-plete structure or complete microtubules was studied in two organisms, the phytoflag-ellate Polytoma papillatum and the phorid fly Megaselia scalaris, using transmission electron microscopy. In the alga, hook-shaped appendages on cytoplasmic and spindle microtubules were detected. These resulted from the lateral association of a curved ribbon of protofilaments with the surface of a complete microtubular wall. In the fly, an S-shaped protofilament sheet was found embedded in the kinetochore plate of a prometaphase I spematocyte. Tracing of the S-shaped element towards the spindle pole revealed that it was formed by the lateral junction of two curved protofilament sheets. In all cases, the C-shaped protofilament sheets represented the endings of complete micro-tubules. Incomplete microtubules are generally considered as representing intermediates of microtubule assembly and disassembly. Since high molecular weight proteins are believed to be responsible for maintaining microtubule-microtubule spacing, it is hypo-thesized that the endings of growing and shrinking microtubules are sparsely studded with these proteins; their depletion allows lateral microtubule contacts. In addition, the microtubule-microtubule contacts may be rendered possible by the flexibility of the slender elongated microtubule-associated molecules. Relatively long C-shaped proto-filament appendages (0.6-1.4 μm) were detected in this study. Therefore, it is plausible to assume that the protofilament sheets are stabilized by contact with one another or with an intact tubule wall.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970170108
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  • 7
    Electronic Resource
    Electronic Resource
    Expression of four myosin heavy chain isoforms with development in mouse uterus (1993)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 25 (1993), S. 358-368 
    Details
    ISSN: 0886-1544
    Keywords: smooth muscle ; smooth muscle myosin ; nonmuscle myosin ; myosin isoforms ; cellular myosin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In smooth muscle tissue, two or three isoforms of myosin heavy chain (MHC) have been reported (SM1, SM2, and/or NM). In mouse uterus tissue, four bands in the region of the MHC's can be resolved on high resolution SDS polyacrylamide gels. Western blots using smooth muscle (SM) MHC-specific and nonmuscle (NM) MHC-specific polyclonal antibodies show the upper two bands in the MHC region are SM isoforms, whereas the lower two bands are NM isoforms. One-dimensional peptide maps of these four bands show each to have a unique pattern of polypeptide fragments following α-chymotrypsin digestion. Developmental expression of myosin heavy chains (MHC) in mouse uterus, aorta, bladder, and stomach (6 ages, 10-150 days) was determined using tissue homogenates. In the uterus, both SM MHC's show an increase in relative content with increasing age, whereas the NM MHC's show a decrease. The mouse aorta shows a significant increase in the SM MHC's and a significant decrease in the NM MHC from day 10 to day 30, which is similar to data reported for the rat aorta. Whereas both the bladder and stomach contain relatively small amounts of NM MHC's (∼ 10% or less), these quantities do show decreases with development. The SM1:SM2 ratio for the uterus remains high (3.4 at 150 days) through development; the aorta, bladder, and stomach also start out high, but tend toward 1.0 in the 150-day animals. The presence of four MHC isoforms in the uterus with unique developmental regulation of expression is consistent with hypotheses of unique functional roles for these isoforms. © 1993 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970250406
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  • 8
    Electronic Resource
    Electronic Resource
    Kinesin does not support the motility of zinc-macrotubes (1995)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 30 (1995), S. 146-152 
    Details
    ISSN: 0886-1544
    Keywords: zinc-sheets ; macrotubes ; kinesin ; electron microscopy ; microtubules ; tubulin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Moving along a microtubule, kinesin follows a course parallel to the protofilaments; but it is not known whether kinesin binds exclusively on a single protofilament. The presence of zinc during tubulin polymerization induces sheets where neighboring protofilaments are antiparallel. If kinesin could support the motility of these zinc-sheets, then the binding site for a kinesin molecule would be limited to a single protofilament.Kamimura and Mandelkow [1992: J. Cell Biol. 118:865-75] reported that kinesin moves along zinc-sheets. We found that zinc-sheets grown under their conditions often had a microtubule-like structure along one edge. We confirmed the possibility that the motility observed by Kamimura and Mandelkow [1992: J. Cell Biol. 118:865-75] is attributed to the microtubule-like structure rather than the zinc-sheet.To resolve the question of whether kinesin can recognize an antiparallel protofilament lattice, we investigated the kinesin-mediated motility of zinc-macrotubes. At higher free zinc concentrations, zinc-sheets roll up as macrotubes, free of edges. In the presence of 10 m̈M taxol and 100 nM free Zn2+ at pH 6.8, the samples were shown by electron microscopy to contain only macrotubes. Under these buffer conditions, kinesin could bind strongly to axonemal doublets in the presence of AMP-PNP, and generate motility in the presence of ATP, but kinesin did not bind to nor move the macrotubes. This shows that kinesin cannot bind efficiently to nor move on the anti-parallel lattice; it is possible (though not necessary) that the groove between two parallel protofilaments is required for kinesin's motility. © 1995 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970300206
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  • 9
    Electronic Resource
    Electronic Resource
    Reduced shear stress: A major component in the ability of mammalian tissues to form three-dimensional assemblies in simulated microgravity (1993)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 51 (1993), S. 301-311 
    Details
    ISSN: 0730-2312
    Keywords: integrated rotating-wall vessel ; shear stress ; simulated microgravity ; three-dimensional tissues ; microcarriers ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: BHK-21 cells were cultured under various shear stress conditions in an Integrated Rotating-Wall Vessel (IRWV). Shear ranged from 0.5 dyn/cm2 (simulated microgravity) to 0.92 dyn/cm2. Under simulated microgravity conditions, BHK-21 cells complexed into three-dimensional cellular aggregates attaining 6 × 106 cells/ml as compared to growth under 0.92 dyn cm2 conditions. Glucose utilization in simulated microgravity was reduced significantly, and cellular damage at the microcarrier surface was kept to a minimum. Thus, the integrated rotating wall vessel provides a quiescent environment for the culture of mammalian cells. © 1993 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240510309
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  • 10
    Electronic Resource
    Electronic Resource
    Blood group antigens and integrins as biomarkers in head and neck cancer: Is aberrant tyrosine phosphorylation the cause of altered α6β4 integrin expression? (1993)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 53 (1993), S. 223-232 
    Details
    ISSN: 0730-2312
    Keywords: squamous cell carcinoma ; ABH antigens ; H-type-2 antigen ; α6β4 integrin ; prognosis ; protein tyrosine phosphatase ; hemidesmosomes ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Head and neck cancer is a capricious disease that varies greatly in its clinical behavior. The development of biomarkers that can distinguish between biologically aggressive and indolent tumors has been a long term goal of our laboratories. Predictive markers applicable to biopsy specimens should facilitate clinical management through early identification of patients at greatest risk for early relapse or metastatic spread. Two prominent cell surface markers that we identified by raising monoclonal antibodies to squamous cell carcinomas are blood group antigens and the A9 antigen/α6β4 integrin. Both of these markers are abnormally displayed in squamous cancers of the head and neck and serve as indicators of early relapse. Loss of blood group antigen expression is a stronger single indicator than is overexpression of the α6β4 integrin. However, use of both markers together is a stronger predictive indicator than is either alone. We know little about the function of the blood group antigens in squamous cells except that the mature antigens are associated with differentiation. Similarly, the function of the α6β4 integrin is also not fully understood. Integrin α6β4 is thought to serve as an extracellular matrix receptor, but its ligand has not been confirmed. In resting epithelium, the α6β4 integrin is polarized to the basal aspect of the basal cell as a component of the hemidesmosome, the anchoring structures of the epithelia. This basal polarization is lost in migrating normal squamous cells and squamous carcinomas. Tyrosine phosphorylation of the β4 subunit is absent or greatly reduced in malignant cells and this may be a critical signal for subcellular localization of α6β4 and cell anchoring. On the basis of our current experimental results, we postulate that tyrosine phosphorylation of the β4 subunit is a reversible signal that regulates cell migration in normal and malignant cells, and may therefore be an important initial event in the metastatic cascade.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240531033
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