| We propose a systematic method of synthesizing robust macromolecules of any desired shape with precise and total structural control. It involves assembly of 3D objects from a few fundamental and carefully designed \molecular building blocks" in a \treelike leaf-to-root" fashion, followed by a later \global rigidizing" reaction. We propose three diierent sets of abstract primitive operations, ...

Tight control of synapse formation ensures that neurons connect to appropriate targets. In this issue of Neuron, Klassen et al. identify ARL-8 GTPase as a regulator of presynaptic assembly. Without ARL-8, presynaptic material aggregates en route to its destination, suggesting that ARL-8 acts like a dispersant to prevent premature synaptic assembly in the axon.