Density gradient isolation of sea urchin adherons

The calcium-magnesium-free sea water (CMFSW) dissociation supernatant (DS), isolated by disaggregating Strongylocentrotus purpuratus blastulae, specifically promotes reaggregation of S. purpuratus blastula cells. The approach used to investigate cellular adhesion in the sea urchin was to examine the CMFSW supernatant, DS, obtained from disaggregating blastula stage embryos for adhesion promoting molecules that might have been released during the disaggregation process. Attempts to purify the active components within DS by rate density gradient centrifugation gave results indicating that aggregation promoting activity resides in particles and particle aggregates ranging from 4S to greater than 53S. We termed these adhesion mediating components "aqherons", after the term used by Schubert and colleagues. The adherons were found to contain proteins ranging from 12 to greater than 280 kD, as determined by SDS polyacrylamide gel electrophoresis. These adherons appear to be responsible for the promotion of cell reaggregation displayed by DS.