Species-specific aggregation factor in sponges
- 37 Downloads
Isolated cells from the siliceous spongeGeodia cydonium have been studied with respect to their partition behaviour in a two-phase aqueous polymer system. With this method it is possible to determine subtle changes in the cell surface charge. Addition of a homologous aggregation factor to the isolated cells lowers the partition rate, a finding which indicates that after binding of the aggregation factor to the cells their surface charge is reduced. The partition rate of the cells is strongly correlated with their content of membranebound sialic acid.
Sixty-nine percent of the total, membrane-bound hexuronic acid is associated with the aggregation receptor; 1.8×107 aggregation receptor molecules are present on the surface of one cell which means that the average surface density amounts to 2.8×105 molecules per μm2.
Removal of the aggregation receptor molecules from the cell surface results in a decrease of the partition rate in the two-phase system. After charging the receptor-depleted cells with soluble aggregation receptor, the partition behaviour of these cells can be reconstituted.
KeywordsSurface Charge Sialic Acid Surface Density Polymer System Aggregation Factor
calcium- and magnesium-free artificial sea water
CMF plus EDTA
calcium- and magnesium-containing artificial sea water
Unable to display preview. Download preview PDF.
- Albertson, P.A.: Partition of Cell Particles and Macromolecules. New York: Wiley 1972Google Scholar
- Avigard, G.: Colorimetric assays for hexuronic acids and some keto sugars.In: Methods in Enzymology (W.A. Wood, ed.) Vol. 41, pp. 29–31. New York: Academic Press 1975Google Scholar
- Curtis, A.S.G.: The cell surface: Its molecular role in morphogenesis. London: Logos Press 1967Google Scholar
- Dubois, M., Gilles, K.A., Hamilton, J.K., Rebers, P.A., Smith, F.: Colorimetric method for determination of sugars and related substances. Z. anal. Chem.,28, 350–356 (1956)Google Scholar
- Kemp, R.B., Lloyd, C.W., Cook, G.M.W.: Glycoproteins in cell adhesion.In: Progress in Surface and Membrane Science (J.F. Danielli et al., ed.) Vol. 7, pp. 271–318. New York: Academic Press 1973Google Scholar
- Müller, W.E.G., Müller, I., Zahn, R.K., Kurelec, B.: Speciesspecific aggregation factor in sponges. VII. Effect on cyclic AMP and cyclic GMP metabolism in cells fromGeodia cydonium: Cell and Tiss. Kinet., in press (1977)Google Scholar
- Zahn, R.K., Müller, W.E.G., Geisert, M., Reinmüller, J., Michaelis, M., Pondeljak, V., Beyer, R.: Species-specific aggregation factor in sponges. I. Characterization of the large circular proteid particle. Cell Differentiation,5, 129–137 (1976)Google Scholar