Chemical dissolution and in vitro reconstruction of sponge cell adhesions : I. Isolation and functional demonstration of the components involved

Abstract

The purpose of this work was to study the mechanism of cell adhesion using aggregation of dissociated sponge cells as the experimental system. A method of chemical dissociation was developed for marine sponges using cold calcium- and magnesium-free sea water. The viable, single cells resulting from this dissociation were able to aggregate and develop into functional sponges. Rotation-mediated aggregation was used to study various aspects of the aggregation of sponge cells. Using these techniques, a specific requirement for the divalent cations calcium and magnesium was established for sponge cell adhesion. Low temperature was found to inhibit adhesion of chemically dissociated cells even when the divalent cations were added back to the cells. Mechanically dissociated cells aggregated rapidly at low temperatures. This difference was shown to be due to a factor released into the supernatant during chemical dissociation of sponge tissue. When this factor was added back to the chemically dissociated cells along with divalent cations, they adhered rapidly at low temperatures. This factor was species specific, causing adhesion only of cells from the same species. These results were interpreted to indicate that the sponge cell adhesion was composed of three basic components: the cell surface, divalent cations, and an intercellular material. These components had been separated during chemical dissociation and were capable of spontaneously and species specifically reassembling themselves to rerorm an apparently normal cell adhesion. The implications of these results for models of cell adhesion are discussed.