Abstract

The unfertilized sea urchin egg is a metabolically quiescent cell. Fertilization results in the activation of a variety of metabolic and biosynthetic pathways, including a 20‐ to 40‐fold increase in the rate of protein synthesis by 2 h after fertilization. This increase is regulated at a purely translational level without the need for new transcription. The greatest part of this increase is due to the translation of stored maternal mRNAs which were not translated in the egg. There is also a 2‐to 3‐fold increase in the peptide elongation rate. The molecular and physiological mechanisms responsible for this activation process are beginning to be understood, and turn out to be much more complex than was anticipated.