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  • 1
    Digitale Medien
    Digitale Medien
    Characteristic modifications of the breathing pattern of mice to evaluate the effects of airborne chemicals on the respiratory tract (1993)
    Springer
    Archives of toxicology 67 (1993), S. 478-490 
    Details
    ISSN: 1432-0738
    Schlagwort(e): Breathing pattern ; Mice ; Airborne chemicals ; Respiratory tract
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract A system was developed for exposure of unanesthetized mice to airborne chemicals and for continuous measurement of their breathing pattern prior to, during and following exposure. By measuring inspiratory and expiratory airflows (VI and VE), and integration with time to yield tidal volume (VT), we obtained characteristic modifications to the normal breathing pattern. These permitted recognition that a specific portion of the respiratory tract was affected by the selected airborne chemicals. Following recognition, we also quantitated the degree of effect using one specific measurement in each case. An effect on the upper respiratory tract, induced by the sensory irritant, 2-chlorobenzylchloride, was quantitated by measuring a decrease in respiratory frequency. An effect on the conducting airways, induced by the airway constrictor, carbamylcholine, was quantitated by a decrease in VE at the mid-point of VT. An effect at the alveolar level, induced either by the vagal nerve ending stimulant, propranolol, or by the pulmonary irritant, machining fluid G, was quantitated by an increase in the length of a pause induced at the end of expiration. The system is easy to construct and operate and can be used to rapidly evaluate the effects of airborne chemicals on the respiratory tract.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01969919
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  • 2
    Digitale Medien
    Digitale Medien
    Three microtubule-organizing centers are required for ascus growth and sporulation in the fungus Sordaria macrospora (1992)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 22 (1992), S. 257-273 
    Details
    ISSN: 0886-1544
    Schlagwort(e): fungal cytoskeleton ; microtubules ; nocodazole ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: The microtubule system of the Sordaria macrospora ascus was examined by antitubulin immunofluorescence, without the removal of the cell wall. The complex cytoskeleton revealed three possible microtubule-organizing centers (MTOCs): the spindle pole body (SPB), the nuclear envelope, and an apical organizing center. MPM-2, a mitotic phosphoprotein antibody which reacts with MTOCs, stained the apical center in a developmentally specific manner, and the nuclear envelope and SPB in a cell cycle-dependent fashion. Nocodazole was used in both high (10-15 μg/ml) and low (0.5 μg/ml) concentrations to depolymerize the networks and reveal their points of origin and recovery. The apical center was active from prophase I to the end of first meiosis. The nuclear envelope was the site of microtubule nucleation in early prophase and at the telophase/interphase transition, while SPBs were active in both nuclear division and sporulation.Mutant strains deficient in sporulation and with aberrant morphology were analyzed by antitubulin and MPM-2 immunofluorescence. Shape mutants showed abnormal or absent apical organizing centers and abnormal cortical microtubule patterns, indicating a possible role for the cortical network in the establishment and maintenance of ascus shape. © 1992 Wiley-Liss, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970220406
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  • 3
    Digitale Medien
    Digitale Medien
    Taxol induces microtubule assembly at low temperature (1981)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1981), S. 445-454 
    Details
    ISSN: 0886-1544
    Schlagwort(e): taxol ; microtubules ; polymerization ; tubulin ; mitotic inhibitor ; protein self-assembly ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Dissociated bovine brain microtubule protein has been shown to reassemble at 0°C in the presence of the drug taxol. Tubulin polymerization was monitored both by electron microscopy of the polymeric structures and by incorporation of tritiated GTP into filterable polymeric structures. Most of the labeled guanine nucleotide uptake into tubulin polymeric structures occurred in the first 30 minutes of incubation with the drug. The initial polymerization event results in the formation of protofilamentous tubulin ribbons. The first microtubules were noted after 1 hour of incubation with the drug. After 20 hours of incubation at 0°C with taxol, the bulk of the polymerized tubulin appeared to be in the form of microtubules. Cold-stable tubulin rings with a mean diameter of 34 nm were present in the reaction mixture before the addition of taxol and throughout the 20-hour incubation. Most of the rings were apparantly not involved in the taxol-induced microtubule assembly. The results are consistant with a model whereby taxol induces an initial formation of protofilamentous ribbon structures, mostly from free tubulin dimers, and a slower subsequent folding of the ribbon structures into microtubules.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970010405
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  • 4
    Digitale Medien
    Digitale Medien
    Two different monoclonal antibodies to alpha-tubulin inhibit the bending of reactivated sea urchin spermatozoa (1982)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 2 (1982), S. 599-614 
    Details
    ISSN: 0886-1544
    Schlagwort(e): monoclonal antibodies to tubulin ; radioimmune assay ; immunoautoradiography ; Western blots ; immunofluorescence ; tubulin heterogeneity ; eukaryotic flagellar motility ; immunomotility ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Two monoclonal antibodies reactive for α-tubulin but not for β-tubulin have been prepared, characterized in terms of their relative binding to tubulins from differnt sources by a solid-phase binding assay, immunoautoradiography, and indirect immunofluorescence, and utilized to study flagellar motility. Our results demonstrate that α-tubulins from different species, and even from different tissues of the same species, are nonidentical. Especially interesting was the observation that one of the antibodies, Ab2, immunofluorescently stained microtubules of chick embryo fibroblast cells, but was completely unreactive for microtubules of rat kangaroo (PtK2) fibroblasts; a different antibody, Ab1, stained both cell types. Results of these and additional experiments clearly show that Ab1 and Ab2 recognize discrete and different epitopes on α-tubulin.Monoclonal antitubulins Ab1 and Ab2 each inhibited the bend amplitude of reactivated sea urchin spermatozoa without affecting beat frequencies or the ability of the outer doublet microtubules to slide past each other in elastase-digested models. These results, together with those obtained previously using rabbit polyclonal antitubulin antibodies [Asai and Brokaw, 1980], demonstrate that inhibition of bend amplitude is a common property of antitubulin antibodies and is not due to the binding of antibodies to one specific site on the axoneme. Our results suggest that tubulin subunit conformational changes may occur on the outer doublet lattice and may be integrally involved in the mechanism and control of flagellar bending.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970020608
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  • 5
    Digitale Medien
    Digitale Medien
    Thrombin, epidermal growth factor, and phorbol myristate acetate stimulate tubulin polymerization in quiescent cells: A potential link to mitogenesis (1992)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 23 (1992), S. 265-278 
    Details
    ISSN: 0886-1544
    Schlagwort(e): growth factors ; phorbol 12-myristate 13-acetate ; microtubule-tubulin equilibrium ; initiation of DNA synthesis ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Previous studies suggest that alterations in the microtubule (MT)-tubulin equilibrium during G0/G1 affect mitogenesis. To determine the effect of growth factors on the MT-tubulin equilibrium, we developed a radioactive monoclonal antibody binding assay (Ball et al.: J. Cell. Biol. 103:1033-1041, 1986). With this assay, 3H-Ab 1 - 1.1 binding to cytoskeletons in confluent populations of cultured cells is proportional to the number of tubulin subunits polymerized into MTs. We now show that purified α-thrombin increases 3H-Ab 1 - 1.1 binding to cytoskeletons of serum-arrested mouse embryo (ME) fibroblasts from 1.5- to 3-fold. This stimulation is dose-dependent and correlates with concentrations of thrombin required for initiation of DNA synthesis. Other mitogenic factors, epidermal growth factor (EGF) and phorbol 12-myristate 13-acetate (PMA), also stimulate MT polymerization. Addition of colchicine (0.3 μM) eight hours after growth factor addition blocks stimulation of 3H-thymidine incorporation by thrombin, EGF, or PMA, suggesting that tubulin polymerization or subsequent events triggered by MT polymerization are required for cells to enter a proliferative cycle. Consistent with models for autoregulation of tubulin synthesis, thrombin, EGF, and PMA all increase tubulin synthesis 9 to 15 hr after growth factor addition, raising the possibility that the decrease in free tubulin and subsequent stimulation of tubulin synthesis is linked to progression of cells into a proliferative cycle. Colchicine addition to these cells also stimulates DNA synthesis, but colchicine-stimulated cells enter S phase 6 to 8 hr later than those stimulated by growth factors. This delayed stimulation may be related to the time required for degradation of tubulin- colchicine complexes below a critical level. These data suggest that regulation of cell proliferation may be linked to increased MT polymerization and the resulting decrease in free tubulin pools. © 1992 Wiley-Liss, Inc.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970230406
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  • 6
    Digitale Medien
    Digitale Medien
    Regulation of cell motility, morphology, and growth by sulfated glycosaminoglycans (1986)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 6 (1986), S. 273-281 
    Details
    ISSN: 0886-1544
    Schlagwort(e): heparin ; glycosaminoglycans ; fibronectin ; cell growth factors ; cell migration ; cell adhesion ; cell morphology ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Due to the recent observation that heparin binds to several growth factors and cell adhesion molecules, the effect of heparin on biological processes governed by growth factors and cell adhesion molecules was investigated. Pharmacological doses of heparin were found to alter cell growth rate, cellular morphology, and cell motility.Concentrations (μg/ml) of heparin or dextran sulfate decreased cell growth rate, but not the final cell density attained in plateau phase. The effect of heparin on cell growth rate was most pronounced when cells were cultured in low concentrations of serum. A heparin-induced decrease in cell growth rate could be reversed by addition of platelet-derived growth factor (PDGF), a heparin-binding growth factor.Heparin altered the morphology of all cell lines studied to various degrees. The effect of heparin on cell morphology was quantitated by measuring the heparin-induced change in cell surface area. HT-1080 and HeLa cells nearly doubled in surface area upon exposure to 10μg/ml heparin. Since several heparin-binding cell adhesion proteins mediate both cell spreading and cell migration, the influence of heparin on cell migration was investigated with an improved version of the phagokinetic track technique. Low concentrations of heparin and dextran sulfate were found to increase the rate of cell migration in a dose-dependent fashion.Since the quantitative effect of heparin on cell growth rate, morphology, and migration depends on the cell line studied, it is suggested that three separate phenomena may be involved. The results presented indicate a central role for sulfated glycosaminoglycans in the control of both cell growth and cell-cell interactions.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cm.970060304
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  • 7
    Digitale Medien
    Digitale Medien
    Spatiotemporal expression of pregnancy-specific glycoprotein gene rnCGM1 in rat placenta (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Developmental Dynamics 198 (1993), S. 171-181 
    Details
    ISSN: 1058-8388
    Schlagwort(e): Pregnancy-specific glycoprotein ; Carcinoembryonic antigen ; Trophoblast giant cell ; spongiotrophoblast ; embryo ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: As a basis towards a better understanding of the role of the pregnancy-specific glycoprotein (PSG) family in the maintenance of pregnancy, detailed investigations are described on the expression of a recently identified rat PSG gene (rnCGM1) at the mRNA and protein levels. Using specific oligonucleotide primers, rnCGM1 transcripts were identified after reverse transcription, polymerase chain reaction, and hybridization with a radiolabelled, internal oligonucleotide. Transcripts were only found in significant amounts in placenta. In situ hybridization visualized rnCGM1 transcripts at day 14 post coitum (p.c.), in secondary trophoblast giant cells and in the spongiotrophoblast. Only those secondary giant cells lining the maternal decidua were positive. In contrast, primary giant cells did not contain rnCGM1 mRNA. At day 18 p.c., rnCGM1. transcripts were almost exclusively detectable in the spongiotrophoblast. No rnCGM1 transcripts were found in rat embryos of these two developmental stages. Rabbit antisera were generated against the amino-terminal immunoglobulin variable-like domain and against a synthetic peptide containing the last 13 carboxy-terminal amino acids of rnCGM1. Bothe antisera recognized a 124 kDa protein in day 18 rat placental extracts as identified by Western blot analysis. The anti-peptide antiserum recognized a 116 kDa protein in the serum of a 14 day p.c. pregnant rat that is absent from the sera of non-pregnant females. Taken together, these results confirm exclusive expression of rnCGM1 in the rat trophoblast, but unlike human PSG, negligible or no expression is found in other organs, such as fetal liver or salivary glands, indicating a more specialized function of rnCGM1. Its spatiotemporal expression pattern is conducive with a potential role of PSG in protecting the fetus against the maternal immune system and/or in regulating the invasive growth of trophoblast cells. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aja.1001980303
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  • 8
    Digitale Medien
    Digitale Medien
    Requirement for glucose during in vitro culture of sheep preimplantation embryos (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 31 (1992), S. 253-257 
    Details
    ISSN: 1040-452X
    Schlagwort(e): Glucose ; Pyruvate ; Lactate ; Embryo culture ; Sheep ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Notizen: Glucose utilization by sheep embryos was examined in 8-cell (N = 36) and blastocyst (N = 36) stages, by measuring conversion of [5-3H]glucose to 3H2O. Fifty percent glucose utilization occurred at 0.79 ± 0.69 mM for 8-cell embryos and ∼0.06 ± 0.15 mM for blastocysts. Development of 1- and 2-cell sheep embryos (N = 264) was examined under different glucose concentrations (0, 1.5, 3, or 6 mM) and in the presence or absence of 0.33 mM pyruvate and 3.3 mM lactate (PL). Overall, the presence of glucose was detrimental (P 〈 0.001) to embryonic development. By contrast, the presence of pyruvate and lactate was beneficial (P〈0.001) to development. An interaction was observed between the concentration of glucose and presence or absence of PL (P 〈0.05). An optimum level of glucose occurs at 0-3 mM in the presence of PL (P ±0.1). Development to the blastocyst stage was observed in medium when supplemented with amino acids and albumin alone. Thus, glucose metabolism is not critical for embryonic development, but beneficial at low concentrations. High concentrations can inhibit development, possibly by inhibiting the tricarboxylic acid (TCA) cycle. Sheep embryos may also be using amino acids as an energy source for development.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/mrd.1080310405
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  • 9
    Digitale Medien
    Digitale Medien
    Developmentally regulated neural protein EAP-300 is expressed by myocardium and cardiac neural crest during chick embryogenesis (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Developmental Dynamics 203 (1995), S. 51-60 
    Details
    ISSN: 1058-8388
    Schlagwort(e): EAP-300 ; Chick embryo ; Heart development ; Purkinje fiber ; Neural crest ; HNK-1 ; Connexin42 ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: The spatiotemporal distribution of EAP-300 (embryonic avian polypeptide of 300 kDa) was analyzed in embryonic chick heart using immunohistochemistry and confocal microscopy. EAP-300 is a developmentally regulated protein initially characterized in neural cells from chick retina. Myocardial cells all along the early tubular heart were ubiquitously immunolabeled for EAP-300 by embryonic day 2 (E2, Stage 13). At E5 (Stage 24), myocardial EAP-300 expression levels remained significant in both atrial and ventricular myocardium. At E6 (Stage 28), distinct populations of EAP-300 immunolabeled cells were also observed external to the heart, in septal mesenchymal tissue and neural ganglia adjacent to the outflow tract; these cell populations were confirmed as neural crest-derived by co-localization of EAP-300 and HNK-1. At E13 (Stage 39), myocardial immunolabeling for EAP-300 was no longer ubiquitous, but increasingly restricted to conduction tissues, including the atrioventricular bundle and subendocardial Purkinje cells. This restriction of immunolabeling could be demonstrated definitively at E15 (stage 41), by which stage subendocardial and periarterial Purkinje fibers were clearly immunoreactive for EAP-300 and several known markers of chick conduction tissue, including specific myosin heavy chain isoforms and connexin42, a gap junctional protein preferentially expressed by Purkinje fibers. Just prior to hatching at E21 (Stage 46), immunolabeling of conduction tissues was reduced, although still above that of non-conductile myocardium. This spatiotemporal map of cardiac EAP-300 expression indicates that it is independently and transiently expressed in early myocardium, cardiac conduction tissue, and neural crest derivatives during development. ©1995 Wiley-Liss, Inc.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aja.1002030106
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  • 10
    Digitale Medien
    Digitale Medien
    Expression of homeobox genes Msx-1 (Hox-7) and Msx-2 (Hox-8) during cardiac development in the chick (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Developmental Dynamics 197 (1993), S. 203-216 
    Details
    ISSN: 1058-8388
    Schlagwort(e): Homeobox genes ; Cardiogenesis ; Conduction system ; Endocardial cushions ; In situ hybridisation ; Chick embryo ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: The vertebrate homeobox genes Msx-1 and Msx-2 are related to the Drosophila mshgene and are expressed in a variety of tissues during embryogenesis. We have examined their expression by in situ hybridisation during critical stages of cardiac development in the chick from stages 15 + to 37. Msx-1 expression is apparent in a number of non-myocardial cell populations, including cells undergoing an epithelial to mesenchymal transformation in the atrioventricular and the outflow tract regions that play an integral role in heart septation and valve formation. Msx.2 expression is restricted to a distinct subpopulation of myocardial cells that, in later stages, coincides morphologically with the cardiac conduction system. The timing of Msx-2 expression suggests that it plays a role in conduction system tissue formation and that it identifies precursor cells of this specialised myocardium. The pattern of Msx-2 expression is discussed with reference to current models of conduction tissue development. © 1993 Wiley-Liss, Inc.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aja.1001970305
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