Nucleic acid polymerizing enzymes in developing Strongylocentrotus franciscanus embryos.

DNA-dependent RNA polymerase, DNA-Dependent DNA polymerase, and terminal riboadenylate transferase (TRT) activities have been measured after DEAE-Sephadex chromatography of whole cell extracts prepared from eggs and staged embryos of the urchin, Stronglyocentrotus franciscanus. Activity of each of these three polymerase classes is present in the egg, and the total activity per embryo is constant throughout embryogenesis to the pluteus stage (approximately 1000 cells). Thus the egg appears to contain sufficient DNA polymerase, RNA polymerase, and TRT TRT for embryogenesis. The increases in the synthesis of DNA, RNA and polyadenylated RNA tracts observed after fertilization must be due to the activation of the preexisting egg enzymes. Separation of the egg into nucleate and anucleate halves demonstrates that the RNA polymerases are not restricted to the egg nucleus. During development, the enzymes become progressively more associated with the cell nucleus. The egg extracts contain low activities (approximately 6% total) of RNA polymerase II as measured by sensitivity to alpha-amanitin. This is confirmed by resolution of the RNA polymerase forms I, II, and III by gradient sievorptive elution on DEAE-Sephadex. Later stage embryos contain more nearly equal activities of RNA polymerase, I, II, and III, although the total RNA polymerase activity per embryo is not changed. Additionally, two chromatographicallly distinct species of RNA polymerase III are detected, one of which is observed only in later stages. Thus interconversion of enzymes via addition of new subunits or coordinate synthesis and loss of enzyme species must occur.