Purification and characterization of a species-specific aggregation factor in sponges

Abstract

The events during re-aggregation of sponge cells, dissociated in Ca 2+- and Mg 2+-free artificial sea water, containing trypsin, can be subdivided into three phases. The first event is the formation of primary aggregates with a diameter of 82 μm. It is Ca 2+- and Mg 2+-dependent and insensitive towards trypsin and puromycin even at high concentrations. The formation of secondary aggregates with a diameter greater than 1 000 μm, is initiated by an aggregation factor. This factor can be separated from the formed elements with calcium- and magnesium-free artificial sea water. Its action is Ca 2+- and Mg 2+-dependent, temperature-independent and insensitive to puromycin. The last event is the reconstitution of functional aquiferous systems in the aggregates. The aggregation factor which was found to be species-specific could be purified 158-fold. Its functional group seems to be a protein probably with polar amino acids in critical positions. Secondary aggregates generated with the aggregation factor show high viability. Some evidence is presented that the aggregation factor may be an annular particle with a circular contour length of 3 500 Å with about 25 filaments attached to it.