Specific patterns of motor neuron loss in cnd-1 mutants affect backward locomotion in Caenorhabditis elegans

In complex organisms, genes determine cellular fates and functions. By studying gene networks during development, we can learn how cellular networks emerge. With only 302 neurons, the C. elegans nervous system is ideal to study these two types of networks. A mutation in the gene cnd-1 was previously found to cause a variable loss of embryonic ventral nerve cord (VNC) motor neurons. cnd-1 is homologous to the mammalian neuroD1 gene that is necessary in establishing neuronal cell fates. Our goal was to understand the role of cnd-1 by focusing on the cell lineages of the embryonic VNC motor neurons. By using transcriptional reporter genes, we found that motor neuron loss occurred in specific cell lineages in cnd-1 mutants. Furthermore, we observed ectopic expression in additional embryonic VNC motor neurons in the posterior, suggesting that cnd-1 may be necessary in establishing the distinct cell fates of the embryonic VNC motor neurons