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  • Cell & Developmental Biology  (109)
  • 1985-1989  (109)
  • 1988  (109)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 134 (1988), S. 460-466 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have previously shown that capillary endothelial cells grown on the surface of three-dimensional collagen gels can be induced to invade the underlying fibrillar matrix and to form capillary-like tubular structures in response to tumor-promoting phorbol esters or the angiogenic agent fibroblast growth factor (FGF). Since both phorbol esters and FGF stimulate phosphorylation of tyrosine residues, we treated endothelial cells with vanadate, an inhibitor of phosphotyrosine-specific phosphatases, to determine whether this agent could induce the expression of an anglogenic phenotype in these cells. We show here that vanadate stimulates endothelial cells to invade collagen matrices and to organize into characteristic tubules resembling those induced by FGF or phorbol esters. We have further observed that vanadate concomitantly stimulates endothelial cells to produce plasrninogen activators (PAs), proteolytic enzymes which are induced by phorbol esters and FGF, and which have been implicated in the neovascular response; this stimulation can be accounted for by an increase in the levels of urokinase-type PA and tissue type PA mRNA. These results suggest a role for tyrosine phosphorylation in the regulation of the angiogenic phenotype in capillary endothelial cells.
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  • 2
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The proliferation of normal human fibroblasts, keratinocytes, and melanocytes in vitro can be controlled by purified polypeptide growth factors and serum. We have studied the cellular expression of the heparin-binding growth factor type 2/basic fibroblast growth factor (HBGF-2/bFGF) gene to determine whether these cell types synthesize mRNA for this mitogen. Our results indicate that normal human fibroblasts synthesize four distinct mRNAs of 7.0, 3.7, 2.2, and 1.5 kilobases, which hybridize to a specific HBGF-2/bFGF cDNA probe. In fibroblasts, the level of all four of these transcripts increases dramatically (more than tenfold) within 4 hours of treatment of quiescent cells with fresh fetal bovine serum. Of the purified growth factors tested, transforming growth factor type-beta also increased HBGF-2/bFGF mRNA abundance, but not to the levels attained by serum treatment. Treatment of fibroblasts with cycloheximide before and during serum treatment blocked the ability of serum to induce the expression of the HBGF-2/bFGF gene. The gene is expressed at low levels in human fibroblasts rapidly growing in serum-free medium and at higher levels in cells rapidly growing in serum-containing medium. In contrast to fibroblasts, mRNA coding for HBGF-2/bFGF is undetectable in proliferating normal human keratinocytes, melanocytes, or mammary epithelial cells. Because keratinocytes and melanocytes proliferate in response to purified HBGF-2/bFGF, our results suggest that HBGF-2/bFGF may mediate the proliferation of epidermal cells through paracrine mechanisms involving stromal fibroblasts. Moreover, we have shown that a human squamous cell carcinoma cell line (SCC-25) expresses mRNA coding for HBGF-2/bFGF, suggesting that the gene may become activated in some carcinomas.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 134 (1988), S. 421-428 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The EGF receptor cDNA has been transfected into receptor-negative Chinese hamster ovary (CHO) cells. A mutant cell line (CHO 11) was isolated that expresses a receptor of lower molecular weight than the EGF receptor from A431 cells (150,000 daltons compared to 170,000 daltons) and which appeared as a doublet on SDS-PAGE. By digestion of the receptor with endoglycosidase F it was shown that an altered pattern of glycosylation could not account for the smaller size of the protein, although it could explain the appearance of the CHO 11 receptor as a doublet protein. A deletion was located to the transfected cDNA and shown to involve the removal of coding sequences for the most C-terminal 20,000 daltons of the EGF receptor, which contains the three major autophosphoryation sites. Despite the loss of these sites the EGF receptor from CHO 11 cells binds EGF, demonstrates protein tyrosine kinase activity in response to EGF, and transduces a mitogenic signal. The CHO 11 receptor protein is still autophosphorylated on alternative tyrosine residues. We conclude that phosphorylation of the three tyrosines (P1, P2, and P3) in the C-terminal domain of the receptor is not required for signal transduction by the EGF receptor in these cells.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 37 (1988), S. 1-9 
    ISSN: 0730-2312
    Keywords: colon cancer ; metastasis ; mucins ; electrophoresis ; lectins ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: We have found that polyacrylamide gel electrophoresis in 3% gels in the presence of sodium dodecyl sulfate is suitable for the separation of cellular glycoproteins having molecular weights ranging from 200,000 to 1,000,000. The gels secured on a rigid support (Gelbond) allow blotting techniques with lectins and antibodies for the detection of glycoproteins. Using these methods we have separated lysates of HT-29 human colon carcinoma cells and detected at Jeast four distinct high molecular weight Sialoglycoproteins having molecular weights of 900,000, 740.000, 560,000, and 450,000. The expression of the 9000,000 component, as revealed by wheat germ agglutinin binding, was much higher in a subline of HT-29 cells established from liver metastases in a nude mouse than it was in the parental cells. The relative intensity of wheat germ agglutinin binding to these four sialoglycoprotein components differs depending upon their growth phase in vitro. These glycoproteins were also detectable by the binding of peanut agglutinin, provided the glycoproteins were previously treated in the gels with mild acid to remove the sialic acid from their carbohydrate chains, suggesting that mucin-type carbohydrate chains are present on these glycoproteins. The same set of glycoproteins can be detected by metabolic labeling of the cells with [3H] glucosamine in tissue culture. Very similar glycoprotein profiles are revealed by metabolic labeling of fresh colon carcinoma tissues with [3H] glucosamine in vitro.
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  • 5
    ISSN: 0730-2312
    Keywords: fatty acid-binding protein ; mechanism of action ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Mammary-derived growth inhibitor (MDGI), a polypeptide growth inhibitor isolated from lactating bovine mammary tissue, previously shown to have extensive sequence homology with fatty acid-binding proteins, was demonstrated to meet the criteria of a fatty acid-binding protein. The protein was found to bind [3H]palmitic acid in a saturable manner and to be complexed with endogeneous free fatty acids. [3H]palmitic acid, when bound to the protein, was more rapidly taken up by the target cells (human mammary carcinoma cells [MaTu]) than was free [3H]palmitic acid, suggesting a lipid carrier function for the inhibitor. It is suggested that the fatty acid-binding properties of MDGI may relate to its ability to inhibit cell growth in vitro and to regulate other cellular functions.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 8 (1988), S. 297-306 
    ISSN: 0741-0581
    Keywords: Defects ; Polymorphs ; Structure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: We review recent results obtained at Northwestern using high-resolution electron microscopy to study high-temperature superconductors. While in general these materials form large, very perfect single crystal grains which display very few imperfections, there is also evidence of slip defects, amorphous regions, and order-disorder transformations. We also report that the gadolinium-based superconductors and in one case yttrium-based superconductors show evidence for some copper solid solubility in the form of copperrich planar defects. The structure of a metastable trigonal polytype is also reported, as are the effects of electron beam and water vapor damage to the materials.
    Additional Material: 9 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Gamete Research 19 (1988), S. 31-39 
    ISSN: 0148-7280
    Keywords: embryo development ; ethylene oxide ; toxicity ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The toxic effects of residual ethylene oxide (EtO), a frequently used gas-sterilant, on embryos either frozen for long-term purposes or stored acutely for 30 min to 9 hr in a fresh condition in 0.25-ml straw containers were evaluated. In Experiment 1, fresh embryos were frozen (using conventional technology) in straws previously aerated for 0 hr to 8 mo after EtO sterilization. With the exception of the 8-mo group in which survival and quality ratings were depressed, embryo viability was not affected significantly by short-term prefreeze and post-thaw exposure to EtO residues. Experiment 2 was conducted to analyze the influence of prefreeze exposure to EtO residues on embryo development in vitro for embryos temporarily stored in previously sterilized straws aerated for different intervals. Compared to non-EtO-sterilized control straws, the development, quality, and viability of embryos exposed to EtO-treated straws were compromised (p 〈 0.05) as the aeration interval decreased and the exposure interval increased. The combined results of both experiments indicate that EtO-treated straws can be used to cryopreserve gametes efficiently, but only if the aeration interval is ≥72 hr and the prefreeze duration of exposure is ≤3 hr.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 10 (1988), S. 185-196 
    ISSN: 0886-1544
    Keywords: mitosis ; kinetochore ; video microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We describe preliminary results from two studies exploring the dynamics of microtubule assembly and organization within chromosomal spindle fibers. In the first study, we microinjected fluorescently labeled tubulin into mitotic PtK1 cells and measured fluorescence redistribution after photobleaching (FRAP) to determine the assembly dynamics of the microtubules within the chromosomal fibers in metaphase cells depleted of nonkinetochore microtubules by cooling to 23-24°C. FRAP measurements showed that the tubulin throughout at least 72% of the microtubules within the chromosomal fibers exchanges with the cellular tubulin pool with a half-time of 77 sec. There was no observable poleward flux of subunits. If the assembly of the kinetochore microtubules is governed by dynamic instability, our results indicate that the half-life of microtubule attachment to the kinetochore is less than several min at 23-24°C.In the second study, we used high-resolution polarization microscopy to observe microtubule dynamics during mitosis in newt lung epithelial cells. We obtained evidence from 150-nm-thick optical sections that microtubules throughout the spindle laterally associate for several sec into “rods” composed of a few microtubules. These transient lateral associations between microtubules appeared to produce the clustering of nonkinetochore and kinetochore microtubules into the chromosomal fibers. Our results indicate that the chromosomal fiber is a dynamic structure, because microtubule assembly is transient, lateral interactions between microtubules are transient, and the attachment of the kinetochores to microtubules may also be transient.
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  • 9
    ISSN: 0886-1544
    Keywords: axoplasmic transport ; motility ; microtubules ; MAPs ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Vesikin, a protein that can associate with squid axoplasmic vesicles or optic lobe microtubuies, has been implicated as a force-generating molecule involved in microtubule-dependent vesicle transport [Gilbert and Sloboda, 1986, 1988]. Because vesikin crossreacts with an antibody to porcine brain microtubule associated protein 2 (MAP 2), studies were conducted to compare squid vesikin and brain MAPs. When taxol stabilized microtubules containing vesikin as a microtubule associated protein were incubated in the presence of ATP, vesikin dissociated from the microtubule subunit lattice. This behavior would be expected for an ATP-dependent, force generating molecule that serves as a crossbridge between vesicles and microtubules. When chick brain microtubules were treated under the same conditions, MAP 2 remained bound to the microtubules while MAP 1 dissociated in a manner similar to vesikin. One dimensional peptide mapping procedures revealed that, although digestion of vesikin and MAP 2 generated several peptides common to both proteins, vesikin and MAP 2 are clearly not identical. Furthermore, the addition of vesikin or MAPS 1 and 2 to purified tubulin stimulated microtubule assembly in a manner dependent on the concentration of added protein. These findings demonstrate that brain MAPs share characteristics common to squid vesikin and support the suggestion that brain MAPs 1 and 2 might act as a force generating complex for vesicle transport in higher organisms.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 9 (1988), S. 205-218 
    ISSN: 0886-1544
    Keywords: F-actin ; actin bundling protein ; cytoimmunofluorescence ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The Ca+2-sensitive actin-binding protein isolated from Dictyostelium discoideum, 30,000-D protein (Fechheimer and Taylor: J. Biol. Chem. 259:4514-4520, 1984;) has recently been localized in filipodia of substrate-adhered amoebae (Fechheimer: J. Cell Biol. 104:1539-1551, 1987). We have determined that this protein has a Mr of 34,000 daltons and is strictly colocalized with actin filaments in both substrate-attached Dictyostelium amoebae and cultured fibroblasts. 3T3 fibroblasts, as well as normal and virally transformed rat kidney fibroblasts (NRK) contain a 34-kilodalton (kD) protein that cross-reacts specifically with antibody to the Dictyostelium bundling protein. Mammalian 34-kD protein is colocalized with F-actin in stress fibers and the cortical cytoskeleton in substratadhered fibroblasts. In substrate-adhered vegetative Dictyostelium, F-actin and 34-kD protein are concentrated in regions of the cell cortex exhibiting filipodia and membrane ridges. Multiple filipodia formed after exposure to the chemoattractant folic acid stain intensely for 34-kD protein, implying participation in the assembly of actin bundles during filipod formation. The cortex of pseudopodia also contained high concentrations of bundling protein, but pseudopod interiors did not. In contrast to vegetative Dictyostelium, F-actin and 34-kD protein were not colocalized in cells that had progressed through the development cycle. In fruiting bodies, 34-kD protein was detected by immunofluorescence microscopy only in prespore cells, while F-actin appeared in stalk cells and spores.
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