Molecular and Cell Biological Studies on Biomineralization by Primary Mesenchyme Cells of the Sea Urchin.

This report to work on the function of sea urchin bone morphogenetic protein 1 suBMP in the sea urchin purpurntiis has progressed in three areas. We are currently examining the developmental expression of the suBMP protein, its function in the developing sea urchin embryo, and its putative protease activity. Previous work had shown that suBMP protein first appears in the hatched blastula stage, rapidly accumulates to the mesenchyme blastula stage, then decays to a lower but persistent level throughout the rest of embryonic development. Using an affinity purified polyclonal antibody to suBMP, we have begun in situ analysis to localize its expression in the mesenchyme blastula immediately preceding gastrulation and prism stage at the onset of spiculogenesis. Preliminary results indicate that suBMP is found in all cells rather than being localized to one specific cell type