Species-Specific Aggregation Factor in Sponges

An aggregation factor (AF) from the siliceous sponge Suberites domuncula has been isolated and purified by the following steps: Sepharose 2 B gel chromatography, sucrose gradient, Nonidet treatment, Sephadex G-100 gel chromatography and DEAE-Sephadex ion-exchange chromatography. By this procedure the AF was purified 1340-fold with a 63% yield nearly to homogeneity. The AF is originally associated with large particles, characterized by a sedimentation of 2200 S. These particles have been visualized electron microscopically; they are characterized by a filament-like shape of a length of 3400 A and a cross-sectional diameter of 230 A. The purified, low-molecular weight AF has a buoyant density…