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  • 1
    Electronic Resource
    Electronic Resource
    Identification and isolation of the primary aggregation factor from the cell membrane of the sponge Geodia cydonium (1985)
    Springer
    Molecular and cellular biochemistry 67 (1985), S. 55-64 
    Details
    ISSN: 1573-4919
    Keywords: aggregation factor ; cell membrane ; glycoproteins ; sponges
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Summary The primary aggregation factor (pAF) of sponge cells is a glycoprotein that is firmly associated with the cell membrane. Polyspecific antibodies (anti-GM) prepared from sera raised against membranes of cells from the siliceous sponge Geodia cydonium were found to inhibit initial aggregation of homologous cells. The inhibition of aggregation, caused by anti-GM was neutralized by pAF. The pAF had been successfully solubilized and enriched by affinity chromatography, gel filtration and density gradient centrifugation, if checked by polyacrylamide gel electrophoresis in the presence of urea. The Mr of the native pAF was approximately 40 000 as estimated by gel filtration; under denaturing conditions three protein species (Mr: 16 500, 15 500 and 13 500) were identified in the pAF preparation. The pAF was precipitable by Ca++ and did not cross-react with antisera against homologous purified secondary aggregation factor and lectin. It is mainly composed of protein (48.0%) and carbohydrate (50.2%). The isolated pAF restored the aggregation potency not only of factor-depleted Geodia cells but also of cells from other Demospongiae. However, the pAF displayed no aggregation enhancing effect on urea-treated cells from species belonging to the Calcispongiae or Hexactinellida. We hypothesize that in contrast to the secondary aggregation, the initial aggregation of Geodia cells is mediated by the one-component system, the bivalent and bifunctional pAF.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00220986
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  • 2
    Electronic Resource
    Electronic Resource
    Sponge aggregation factor: In situ localization by fluorescent monoclonal antibody techniques (1986)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 31 (1986), S. 251-258 
    Details
    ISSN: 0730-2312
    Keywords: aggregation factor ; monoclonal antibodies ; reaggregation ; cell recognition ; Geodia cydonium ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The aggregation factor (AF) from sponges mediates a heterophilic interaction of homologous cells. Applying electron microscopical means, we succeeded only very rarely in identifying the 90 S AF particle in tissue sections from Geodia cydonium. By means of a fluorescent antibody technique, we have now localized the cell binding domain of the AF in situ. Previous studies in this laboratory have led to the identification of the 47-kDa cell binding protein of the AF, using the monoclonal antibody (mab) 5D2-D11 [Gramzow M, Bachmann M, Zahn RK, Uhlenbruck G, Dorn A, Müller WEG, J Cell Biol, 102:1344-1349, 1986]. This mab and mab 7D5, directed against a 92-kDa protein in the AF complex, were chosen for the fluorescent studies. By using mab 5D2-D11, the plasma membranes of cells from different regions in the sponge could be brightly stained. However, mab 7D5 reacted only very weakly with the sponge surfaces. By applying the immuno-blotting technique it was furthermore demonstrated that the cell binding protein is present both in the associated form with AF complex and in a free state. Moreover, it was established that the 47-kDa binding protein is not present in (1) homologous glycoconjugates, (2) lectin, or (3) collagen; these components are known to be involved in cell-matrix interaction.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240310402
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  • 3
    Electronic Resource
    Electronic Resource
    Aggregation of sponge cells: Immunological characterization of the species-specific geodia aggregation factor (1981)
    New York, NY : Wiley-Blackwell
    Journal of Supramolecular Structure and Cellular Biochemistry 17 (1981), S. 1-9 
    Details
    ISSN: 0275-3723
    Keywords: cell aggregation ; aggregation factor ; sponges ; glycoproteins ; Chemistry ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Antibodies were raised against the purified aggregation factor from Geodia cydonium in order to clarify its function during cell aggregation in the homologous and heterologous system. These antibodies inhibited only cell aggregation in the homologous Geodia system and were inactive in the heterologous Tethya lyncurium system. These findings directly indicated that the species-specific reaggregation of sponge cells was initiated by the soluble aggregation factor as already assumed in earlier studies. The amount of neutralizing antibodies was determined by a precipitation reaction with the antigen in capillaries and by microdiffusion. By using the latter technique we got evidence that the Geodia aggregation factor contained a component that was antigenetically related to a galactose-specific lectin present in Geodia cydonium.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jsscb.380170102
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