title: Change in the activity of Cl-,HCO3(-)-ATPase in microsome fraction during early development of the sea urchin, Hemicentrotus pulcherrimus.
abstract: In sea urchin embryos, primary mesenchyme cells, descendants from micromeres produced at the 16-cell stage, form spicules or CaCO3 deposits in their skeletal vacuoles, at the post-gastrula stage. Micromeres isolated at the 16-cell stage also differentiate into spicule-forming cells during their culture at the same time schedule as in the embryos. The present study was planned to observe change in the activity of Cl-,HCO3(-)-ATPase, which was expected to contribute to the carbonate supply for CaCO3 deposition, during development. ATP-hydrolysis in the microsome fraction, obtained from embryos of the sea urchin, Hemicentrotus pulcherrimus, and from micromere-derived cells in culture was stimulated by Cl- and HCO3- in the presence of ouabain and EGTA. The ATP-hydrolysis was inhibited by ethacrynic acid, an inhibitor of Cl-,HCO3(-)-ATPase. The activity of Cl-,HCO3(-)-ATPase in embryos and in micromere-derived cells increased during development, keeping pace with the rate of calcium deposition in spicules. Formation of calcified spicules in the cultured micromere-derived cells was inhibited by ethacrynic acid. These results indicate that Cl-,HCO3(-)-ATPase plays an important role in the mechanism of CaCO3 deposition in the primary mesenchyme cells.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D027321:Anion Transport Proteins; D001757:Blastomeres / Q000201:enzymology; D002478:Cells, Cultured; D008861:Microsomes / Q000201:enzymology*; D010063:Ovum / Q000201:enzymology; D012617:Sea Urchins / Q000196:embryology / Q000201:enzymology*
chemical_list: D027321:Anion Transport Proteins; D000251:Adenosine Triphosphatases; C031652:anion-sensitive ATPases