Nervous breakdown

Like the waistband of your pants after Thanksgiving dinner, neurons have to be able to stretch and then return to shape. On page 269 Hammarlund et al. pinpoint the protein that confers this springiness, showing that neurons lacking the molecule fracture.

Movements such as bending your elbow put strain on neurons, but the source of the cells' elasticity has been a mystery. Hammarlund et al. suspected that the protein β-spectrin was involved. In red blood cells, the protein weaves into a mesh that supports the cell membrane, enabling erythrocytes to rebound after being crushed and dented during their travels through the circulatory system.

The researchers tested spectrin's function in neurons by observing nematodes that lack the protein. In embryonic worms, neurons grew normally between the animals' two nerve cords, indicating that spectrin isn't...