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  • Biochemistry and Biotechnology  (2)
  • Life and Medical Sciences  (2)
  • 03.65.Sq  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 347 (1994), S. 255-265 
    ISSN: 1434-601X
    Keywords: 03.65.Nk ; 03.65.Sq ; 25.70.Bc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The accuracy of the first and second order WKB approximation in describing sub-Coulomb elastic scattering of ions is investigated. Thereby the scattering of non-identical as well as of identical particles is taken into consideration. It is shown that in cases where the behaviour of the scattered ions is not quasi-classical and therefore the first order WKB approximation fails, the second order WKB will be in most cases still a quite good approximation.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0952-3499
    Keywords: autoimmune disease ; Sjögren's syndrome ; lacrimal gland ; membrane traffic ; endocytosis ; protein sorting ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: CD4 T cell antigen recognition requires presentation by major histocompatibility complex Class II molecules (MHC II). B cell surface immunoglobulins recognize antigens independently of MHC II, but activation typically requires CD4 cell cytokines as accessory signals. Plasma membrane-endomembrane traffic in lacrimal gland acinar cells, targets of autoimmune activity in Sjögren's syndrome, may satisfy both requirements. The Golgi protein galactosyltransferase and the lysosomal proteins cathepsin B and cathepsin D appear at the plasma membranes during sustained secretomotor stimulation. The RNA transcription termination factor La, a frequent target of Sjögren's autoantibodies, appears in the acinar cell cytoplasm and plasma membranes during viral infection and during in vitro exposure to cytokines. MHC II cycle through endomembrane compartments which contain La, galactosyltransferase, cathepsin B and cathepsin D and which are sites of proteolysis. This traffic may permit trilateral interactions in which B cells recognize autoantigens at the surface membranes, CD4 T cells recognize peptides presented by MHC II, B cells provide accessory signals to CD4 T cells, and CD4 T cells provide cytokines that activate B cells. Acinar cells stimulate lymphocyte proliferation in autologous mixed cell reactions, confirming that they are capable of provoking autoimmune responses. Copyright © 1998 John Wiley & Sons, Ltd.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1058-8388
    Keywords: M-cadherin antibodies ; N-CAM ; Desmin ; Laminin ; Somite ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Molecules regulating morphogenesis by cell-cell interactions are the cadherins, a class of calcium-dependent adhesion molecules. One of its members, M-cadherin, has been isolated from a myoblast cell line (Donalies et al. [1991] Proc. Natl. Acad. Sci. U.S.A. 88:8024 - 8028). In mouse development, expression of M-cadherin mRNA first appears at day 8.5 of gestation (E8.5) in somites and has been postulated to be down-regulated in developing muscle masses (Moore and Walsh [1993] Development 117:1409 - 1420). Affinity-purified polyclonal M-cadherin antibodies, detecting a protein of approximately 120 kDa, were used to study the cell expression pattern of M-cadherin protein. It was first visualized in somites at E10 1/3 and could be confined to desmin positive, myotomal cells. At all subsequent prenatal stages, M-cadherin was only found in myogenic cells of somitic origin. The detection of the protein at E10 1/3 suggests a translational delay of M-cadherin mRNA of 1 to 2 days (E8.5 vs. E10 1/3). This was further supported by the finding that during differentiation of ES cell line BLC6 into skeletal muscle cells in culture, expression of M-cadherin mRNA can be detected 2 days prior to M-cadherin protein. During prenatal development, the pattern of M-cadherin expression changes: In E10 1/3 embryos and also in myotomal cells of later stages, M-cadherin is evenly distributed on the cell surface. In developing muscle masses (tested at E16 to E18), however, M-cadherin protein becomes clustered most likely at sites of cell-cell contact as indicated by double-labelling experiments: M-cadherin-staining is the positive image of laminin negative areas excluding the presence of a basal lamina at M-cadherin positive sites. Furthermore, M-cadherin is coexpressed with the neuronal cell adhesion molecule N-CAM which has been shown to mediate cell-cell contact in myogenic cells. In summary, our results are in line with the idea that M-cadherin might play a central role in myogenic morphogenesis. © 1994 Wiley-Liss, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: It seems well established that translocation of at least some mRNAs through the nuclear pore is (1) an energy-dependent process, and (2) dependent on the presence of the poly(A) segment attached to most mRNA species. We describe that RNA helicase (RNA duplex unwindase) activity is present in a nuclear envelope (NE) preparation, which also appears to be involved in nucleocytoplasmic RNA transport. This activity unwinds RNA : RNA hybrids. The helicase has a pH optimum of 7.5 and a temperature optimum of 30°C. Applying the sealed NE vesicle system, it was shown that duplex RNA species are readily released from the vesicles in an unidirectional manner, in contrast to single-stranded RNA, which is much slower transported into the extravesicular space. Attachment of a poly(A) segment to the RNA duplex additionally increases the efflux rate of this RNA. Efflux of duplex RNA but not efflux of single-stranded RNA was strongly inhibited by formycin B 5′-triphosphate. Our results suggest that, besides poly(A), duplex structures, if present in a given RNA, modulate and control the export of RNA.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Cell Biochemistry and Function 11 (1993), S. 1-11 
    ISSN: 0263-6484
    Keywords: Prion protein ; prion gene expression ; scrapie ; N2a cells ; mouse neuroblastoma cells ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The scrapie prion protein, PrPSc, is formed from its isoform, the cellular PrPc. There is evidence available indicating that PrPSc is necessary component of the infectious prion particle to cause a series of transmissible spongiform encephalopathies. We have used immunocytochemistry and RNA blotting techniques to investigate if infection with prions results in an increased PrP gene expression. For the experiments we used N2a cells which had been infected with prions (ScN2a cells). We demonstrated by confocal laser scanning microscopy that PrP-protein was present in the nucleus (predominantly in the nucleoli) of ScN2a cells. Analysis of the PrP-mRNA levels both in N2a- and in ScN2a cells using cDNA encoding PrPc revealed no marked alteration of the mRNA steady state level between the two cell strains. Likewise, in run-off experiments no changes in either PrP-specific transcription or in general transcriptional activity were found. The half-life of PrP-mRNA was found to be identical in both cell strains (7 h). Taken together, these results show that PrPSc and /or PrPc is present in the nucleus (nucleoli) of ScN2a cells but does not display and effect on the expression of the PrP gene.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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