Changing synaptic specificities in the nervous system 
of C. elegans: differentiation of the DD motoneurons

During postembryonic development , the DD motoneurons in the nematode Caenorhabditis elegans completely reorganize their pattern of synapses. Ablation of a pair of embryonic precursors results in the absence of this entire class of motoneurons. In their absence animals exhibit two developmentally distinct locomotory defects. The transition period from one defect to the other is correlated with the synaptic reorganization of the DD mns.

Mutations in a gene (unc-123) have been isolated that exhibit locomotory defects similar to those of the ablated adult animals. Genetic and cellular analysis of one of these alleles suggest that the unc-123 gene product may be involved in the reestablishment of functional synapses in these neurons.