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  • Cell & Developmental Biology  (2,509)
  • AERODYNAMICS
  • 1995-1999  (2,608)
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 162 (1995), S. 36-43 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Insulin-like growth factor II (IGF II) regulated tissue-specific gene expression in hepatoma cell lines, but had no effect on expression of tissue-specific genes in primary cultures of E14 and newborn rat liver cells depleted of erythroid cells. No change was observed in these primary cultures with respect to α-fetoprotein (α-FP), albumin, cytokeratin 19 (CK 19), γ-glutamyltranspeptidase (GGT), and IGF II receptors. Two well-differentiated hepatomas, HepG2 and FTO-2B, and a poorly differentiated hepatoma, H4AzC2, did not show increased proliferation in the presence of IGF II, yet showed gene expression changes in response to IGF II. In HepG2 cells, IGF II increased albumin mRNA levels and resulted in a shift from clusters of cells positive to 100% of the cells expressing immunohistochemically detectable albumin. The transcription factor HNF-3β mRNA and protein levels of the bile duct markers, CK19 and GGT, were also increased in the presence of IGF II. Other genes tested were not affected, including α 1-antitrypsin, and two liver specific transcription factors, HNF-4 and HNF-3α. In FTO-2B cells, IGF II increased the expression of albumin, CK19, and GGT, without accompanying changes in albumin and GGT mRNAs. In H4AzC2 cells, IGF II reduced CK19 and OC.3 protein levels and GGT, transferrin, and HNF-3β mRNAs. The effects of IGF II on H4AzC2 cells were not blocked in the presence of an anti-rat IGF II receptor antibody. We conclude that IGF II affects tissue-specific gene expression of hepatomas and qualitative and quantitative aspects of its influence on the hepatomas is dependent on their degree of differentiation. © 1995 Wiley-Liss, Inc.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 42 (1995), S. 200-209 
    ISSN: 1040-452X
    Keywords: Embryo ; Pronucleus ; Microtubules ; Chromosome analysis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Peri-fertilization exposure to Carbendazim (MBC; a microtubule poison) induces infertility and early pregnancy loss in hamsters. Presently, both in vivo and in vitro techniques were employed to characterize the effects of MBC on cellular aspects of fertilization in hamsters. Exposure to MBC during either in vivo or in vitro fertilization (IVF) induced identical morphological abnormalities in the maternal chromatin of zygotes and embryos. These abnormalities included either multiple second polar bodies (PB2), and/or multiple small female pronuclei (PN), or meiotic arrest. Multiple PB2, multiple female PN, multiple PB2 with multiple female PN, or meiotic arrest were exhibited by approximately 31%, 15%, 12%, and 2% of the in vivo zygotes; and 3%, 16%, 36%, and 20% of IVF zygotes, respectively. The effects of MBC persisted to day 2 of pregnancy as indicated by decreased (P ≤ 0.05) embryo development to the two-cell stage and the presence of micronuclei in 6% of two-cell embryos from MBC-treated females. Immunofluorescence analysis of microtubules (MTs) confirmed that MBC disrupted spindle MTs during IVF. Numerical chromosome analysis revealed that a single dose of MBC administered during in vivo fertilization induced aneuploidy in the resulting pronuclear-stage zygotes. The present data point to two mechanisms by which peri-fertilization MBC exposure may induce early pregnancy loss: 1) arrested meiosis with no zygotic cleavage; or 2) induction of zygotic aneuploidy with subsequent developmental arrest. © 1995 wiley-Liss, Inc.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 41 (1995), S. 479-485 
    ISSN: 1040-452X
    Keywords: Oogenesis ; Folliculogenesis ; Meiosis ; Chromatin structure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We investigated the changes in the organization of oocyte nuclear chromatin and nucleolar-associated chromatin throughout folliculogenesis. Zona-free oocytes were isolated from ovaries, grouped into seven classes according to size and chromatin organization, and analyzed after staining with Hoechst 33342. We show that oocyte differentiation from the dictyate stage to the conclusion of maturation is associated with either of two chromatin configurations. Initially, all oocytes are in the NSN configuration (nonsurrounded nucleolus oocytes; characterized by a Hoechst positive-chromatin pattern of small clumps forming a network on the nuclear surface, with a nucleolus nonsurrounded by chromatin). While growing, some of these NSN oocytes continue their development in the NSN configuration, whereas others shift (from class IV on) into the SN configuration (surrounded nucleolus oocytes; characterized by a threadlike chromatin organization that may partially surround the nucleolus or project towards the nuclear periphery). The percentage of SN oocytes increases both with increasing size of the oocyte (class I-III, 10-40 μm in diameter: 100% NSN vs. 0% SN; class VII 70-80 μm in diameter: 47.3% NSN vs. 52.3 SN, in 4-6-week-old females), and with aging (class VII: 94.1% NSN vs. 5.9% SN in 2-week-old females; 11.8% NSN vs. 8.2% SN in 56-week-old females). Further, we suggest as a working hypothesis that those oocytes that switch to the SN chromatin organization early in maturation may not be ovulated, even though this particular chromatin structure normally occurs just prior to ovulation. © 1995 Wiley-Liss, Inc.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 30 (1995), S. 26-37 
    ISSN: 0886-1544
    Keywords: myosin ; myosin-I ; unconventional myosin ; brush border ; epithelia ; membrane ; phospholipid ; fluorescence microscopy ; actin ; calmodulin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Brush border myosin-I (BBMI) is associated with the membrane of intestinal epithelial cells where it probably plays a structural role. BBMI also has been identified on Golgi-derived vesicles in intestinal epithelial cells where it may translocate vesicles into the brush border. However, the mechanochemical activity of BBMI bound to a phospholipid membrane has not been described. This study reports that phospholipid membrane-associated BBMI displays ATPase activity when bound to phospholipids, but does not move actin filaments when associated with a phospholipid bilayer. BBMI does not bind significantly to brush border membrane lipids, which contain about 16% phosphatidylserine (PS), in either a pelleting or planar membrane assay. Similarly, planar membranes containing 20% PS do not bind a significant amount of BBMI. Increasing the concentration of PS to 40% does result in the binding of BBMI to both vesicles and planar membranes. This binding is enhanced with increased Ca2+ concentrations. BBMI retains its ATPase activity when bound to phospholipid vesicles containing 40% PS. However, BBMI attached to a phospholipid bilayer surface does not move actin filaments, even though the amount of BBMI bound to the lipid surface, as reflected by the number of actin filaments associated with bilayer-bound BBMI, is sufficient to observe motility in control experiments. When membrane fluidity is reduced by adding cholesterol to the membrane lipids containing 40% PS, BBMI still binds to the membrane, but again no actin filament motility is observed. The lack of binding by BBMI to brush border membrane lipids and the absence of membrane-associated BBMI mechanical activity suggest that factors in addition to membrane lipids are necessary for membrane-associated myosin-I motility. © 1995 Wiley-Liss, Inc.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 71 (1998), S. 515-523 
    ISSN: 0730-2312
    Keywords: binding ; complex formation ; retinoic X receptor ; TFIIB ; vitamin D receptor ; VDRE ; steroid receptor ; nuclear extract ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The vitamin D receptor (VDR) elicits a transcriptional response to 1,25-dihydroxyvitamin D3 by binding to specific response elements (VDRE) in the promoter of target genes. Retinoic X receptor (RXR) is required for formation of the VDR-VDRE complex when VDR is supplied at physiologic concentrations. When porcine intestinal nuclear extract is used as a source of VDR, two distinct complexes are always observed with native gel electrophoresis. Both complexes contain VDR and RXR. We now show that the faster-migrating complex requires another heretofore unknown nuclear factor for its formation. In addition, we provide evidence that the formation of the slower-migrating complex is enhanced by transcription factor IIB (TFIIB). Using ligand binding assays, we determined that both complexes contain the same ratio of VDR to VDRE. Using RXR subtype-specific antibodies in gel shift assays, we show that the complexes contain more than one RXR subtype. Therefore, the present results demonstrate VDR-RXR-VDRE complexes formed with pig intestinal nuclear extracts contain other proteins and that the complexes formed between VDR and VDRE are not simply heterodimers of VDR and RXR. J. Cell. Biochem. 71:515-523, 1998. © 1998 Wiley-Liss, Inc.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 30 (1995), S. 229-246 
    ISSN: 0886-1544
    Keywords: Listeria monocytogenes ; fluorescence polarization ; actin ; confocal microscopy ; mutant ; infections ; PtK2 cells ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: During its motion inside host cells, Listeria monocytogenes promotes the formation of a column of actin filaments that extends outward from the distal end of the moving bacterium. The column is constructed of short actin filaments that polymerize at the bacteria-column interface. To get a measure of filament organization in the column, Listeria grown in cultured PtK2 cells were studied with steady state fluorescence polarization, confocal microscopy, and whole cell intermediate voltage electron microscopy. Although actin filament ordering was higher in nearby stress fibers than in the Listeria-associated actin, four distinct areas of ordering could be observed in fluorescence polarization ratio images of bacteria: (1) the surface of the bacteria, (2) the cytoplasm next to the bacteria, (3) the outer shell of the actin column, and (4) the core of the column. Filaments were preferentially oriented parallel to the long axis of the column with highest ordering along the long axis of the bacterial surface and in the shell of the tail. The lowest ordering was in the core (where filaments are possibly also shorter with respect to the cup and the shell), whereas in the adjacent cytoplasm, filaments were oriented perpendicular to the column. A mutant of Listeria that can polymerize actin around itself but cannot move intracellularly does not have its actin organized along the bacterial surface. Thus the alignment of the actin filaments along the bacterial surfaces may be important for the intracellular movement. These conclusions are also supported by confocal microscopy and whole mount electron microscopic data that also reveal that actin filaments can be deposited asymmetrically around the long axis of the bacteria, a distribution that may affect the direction of motility of Listeria monocytogenes inside infected cells. © 1995 Wiley-Liss, Inc.
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  • 7
    ISSN: 1040-452X
    Keywords: Myometrium ; Oxytocin ; Intracellular Ca2+ concentration ; Ca2+ channels ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: This study investigated the underlying mechanisms of oxytocin (OT)-induced increases in intracellular Ca2+ concentrations ([Ca2+]i) in acutely dispersed myometrial cells from prepartum sows. A dosedependent increase in [Ca2+]i was induced by OT (0.1 nM to 1 μM) in the presence and absence of extracellular Ca2+ ([Ca2+]e). [Ca2+]i was elevated by OT in a biphasic pattern, with a spike followed by a sustained plateau in the presence of [Ca2+]e. However, in the absence of [Ca2+]e, the [Ca2+]i response to OT became monophasic with a lower amplitude and no plateau, and this monophasic increase was abolished by pretreatment with ionomycin, a Ca2+ ionophore. Administration of OT (1 μM) for 15 sec increased inositol 1,4,5-trisphosphate (IP3) formation by 61%. Pretreatment with pertussis toxin (PTX, 1 μg/ml) for 2 hr failed to alter the OT-induced increase in [Ca2+]i and IP3 formation. U-73122 (30 nM to 3 μM), a phospholipase C (PLC) inhibitor, depressed the rise in [Ca2+]i by OT dose dependently. U-73122 (3 μM) also abolished the OT-induced IP3 formation. Thapsigargin (2 μM), an inhibitor of Ca2+-ATPase in the endoplasmic reticulum, did not increase [Ca2+]i. However, it did time-dependently inhibit the OT-induced increase in [Ca2+]i. Nimodipine (1 μM), a Voltage-dependent Ca2+ channel (VDCC) blocker, inhibited the OT-induced plateau by 26%. La3+ (1 μM), a nonspecific Ca2+ channel blocker, abrogated the OT-induced plateau. In whole-cell patch-clamp studies used to evaluate VDCC activities, OT (0.1 μM) increased Ca2+ Current (Ica) by 40% with no apparent changes in the current-voltage relationship. The OT-induced increase in Ica reached the maximum in 5 min, and the increase was abolished by nimodipine (1 μM). These results suggested that (1) activation of OT receptors in porcine myometrium evokes a cascade in the PTX-insensitive G-protein-PLC-IP3 signal transduction, resulting in an increase in [Ca2+]i; (2) the OT-induced increase in [Ca2+]i is characterized by a biphasic pattern, in which the spike is predominately contributed by the intracellular Ca2+ release from the IP3-sensitive pool, and to a lesser extent by Ca2+ influx, whereas the plateau is from increased Ca2+ influx; and (3) the influx is via VDCC and receptor-operated Ca2+ channels. © 1995 Wiley-Liss, Inc.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 66 (1997), S. 441-449 
    ISSN: 0730-2312
    Keywords: mitosin ; CENP-F ; spindle pole ; kinetochore ; centromere ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Mitosin is a nuclear protein of 3,113 amino acids which has been shown to associate with the mitotic apparatus, especially the kinetochore, during mitosis. In this paper we further confirmed its association with the spindle poles in normal monkey kidney CV1 cells by indirect immunofluorescence microscopy. When the carboxyl portion of mitosin containing amino acids 2,094-3,113 (named mitosin-pTN) was stably expressed in rat fibroblast Rat2 cells using a tetracycline-inducible system, strong spindle pole association was observed in addition to expected centromere localization. The same results were achieved in Chinese hamster ovary (CHO) cells. On the other hand, mitosin-pTC containing amino acids 2,756-3,113 was not targeted to spindle poles. Use of the FLAG epitope [Hopp et al., 1988] genetically fused to each amino terminus of these mutants eliminated possible artifacts due to antibody cross-reaction, since the spindle pole localization of wild-type mitosin was confirmed with a FLAG-tagged mutant by an antibody (anti-FLAG M2 monoclonal antibody) irrelevant to antibodies to mitosin. Our data also suggested a possible interaction of mitosin with the spindle microtubules. Interaction of mitosin with the major parts of the mitotic apparatus further implies an important role in mitosis. J. Cell. Biochem. 66:441-449, 1997. © 1997 Wiley-Liss, Inc.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 61 (1996), S. 420-429 
    ISSN: 0730-2312
    Keywords: cell attachment ; gene transcription ; AP1 site; fos/jun ; 1,25(OH)2D3 ; macrophage-like cells ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: 1,25-Dihydroxyvitamin D3 (1,25(OH)2D3) transactivates the avian β3 integrin gene whose promoter contains at least two vitamin D response elements, one of which is in close proximity to a candidate AP1 site (TGACTCA). Since fos/jun and steroid hormones interact to regulate gene expression, we asked whether phorbol-12-myristate-13-acetate (PMA), which stimulates binding of fos/jun to AP1 sites, transactivates the avian β3 integrin gene and, if so, does the phorbol ester modulate 1,25(OH)2D3 induction of the gene. We find the candidate AP1 sequence comigrates with the consensus AP1 sequence on electromobility shift assay when incubated with recombinant c-jun protein. Furthermore, PMA prompts expression of β3 integrin mRNA in the avian monocytic line, HD11. The increase in message reflects transactivation of the β3 gene and is mirrored by plasma membrane appearance of the integrin heterodimer αvβ3. Moreover, attesting to the functional significance of PMA-enhanced αvβ3 expression, cells treated with concentrations of the phorbol ester that induce the β3 gene, spread extensively on plastic, an event blocked by an anti-αv antibody and a peptide mimetic known to inhibit αvβ3-mediated cell attachment. Interestingly, co-addition of 1.25(OH)2D3 and PMA prompts greater expression of αvβ3 than when the cells are exposed to either agent alone and PMA enhances 1,25(OH)2D3-induced β3 integrin mRNA expression. Thus, PMA and 1,25(OH)2D3 impact on the avian β3 integrin gene independently and in combination. © 1996 Wiley-Liss, Inc.
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  • 10
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A new pH indicator, seminaphthofluorescein (SNAFL)-calcein acetoxymethyl ester, was used for intracellular pH (pHi) measurement in living MDCK cells with a laser scanning confocal microscope (LSCM) equipped with an Argon/Krypton laser and dual-excitation and dual-emission (FITC/Texas Red) filter set. SNAFL-calcein excitation maxima are ∼492/540 nm (acid/base) and emission maxima are ∼535/625 nm (acid/base) with a pKa value at ∼7.0. The absorption/emission spectra of SNAFL-calcein indicate that the ratio of emission intensities of its basic/acidic forms is pH dependent. With an Argon/Krypton LSCM, we were able to monitor the acidic and basic forms of this dye simultaneously using dualexcitation (488/568 nm) and dual-emission (525-614 nm/∼615 nm) wavelengths (λs). The simultaneous dual-excitation/emission LSCM system allows for efficient recording of pHi dynamics (time resolution ≍ 1 sec) in living cells. We have analyzed emission stability of the dye at different temperatures (22°C and 37°C) and constant pH, and at the same temperature (22D°C) but various pHs (6.6, 7.0, and 7.4). Bleaching rate is slightly higher at 37°C than that at 22°C. The basic form of the dye (λEm ≍ 625 nm) has a slightly higher bleaching rate than the acidic form (λEm ≍ 535 nm) in standard culture medium (pH 7.3) at either 22°C or 37°C. The pHi in MDCK cells calculated from ratio images (535 nm/625 nm) was 7.19 ± 0.03 (mean ± SEM, n = 20). Calibration experiments show that the useful pH range of SNAFL-calcein appears to be between 6.2 and 7.8, as the dye is difficult to calibrate outside this pH range. © 1995 Wiley-Liss, Inc.
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