Figure 6.

Model of polysomal recruitment dynamics upon fertilization in sea urchin. Before fertilization, translation activity is generally repressed. Fertilization triggers the selective recruitment of a new subset of mRNAs onto polysomes, with over-represented functional categories such as cell cycle, RNA-binding and signaling (recruitment from free mRNAs or small mRNPs before fertilization, large black arrow). The recruitment of some mRNAs depends on the mTOR pathway, either completely or partially, whereas polysomal recruitment of other mRNAs are independent of mTOR (box). Some mRNAs present in stalled polysomes or stored in large mRNPs before fertilization are activated for translation after fertilization (thin black arrow). Fertilization also triggers the selective repression of a small subset of mRNAs translated in the egg before fertilization (dashed gray arrow), but most maternal mRNAs do not change their polysomal behavior (gray arrow).