CHANGING SYNAPTIC SPECIFICATIONS IN THE NERVOUS-SYSTEM OF CAENORHABDITIS-ELEGANS - DIFFERENTIATION OF THE DD MOTONEURONS

During postembryonic development, the DD motoneurons in the nematode C aenorhabditis 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 fr om one defect to the other is correlated with the synaptic reorganizat ion of the DD mns. Mutations in a gene (unc-123) have been isolated th at exhibit locomotory defects similar to those of the ablated adult an imals. Genetic and cellular analyses of one of these alleles suggest t hat the unc-123 gene product may be involved in the reestablishment of functional synapses in these neurons. (C) 1993 John Wiley & Sons, Inc .