Relative effect of transcription-level and translation-level control of protein synthesis during early development of the sea urchin.

Newly synthesized proteins were pulse labeled with radioactive amino acids at several developmental stages of the sea urchin, Arbacia punctulata-in normal embryos and in embryos continuously exposed to the drug Dactinomycin. The soluble proteins were fractionated by electrophoresis through polyacrylamide gels. A simple procedure for complete solubilization of the proteins in slices of gels into a solution of toluene for liquid scintillation counting, and a computer program to display and to compare statistically the distributions of (14)C- and (3)H-labeled proteins fractionated on the same gel, allowed quantitative statements to be made on the relative changes in protein synthesis. The conclusion is that translation-level control provides most of the changes in protein synthesis that occur between fertilization and hatched blastula stage.