Synapses are specialized subcellular structures by which a neuron communicates with other neurons or muscle cells. Most synapses formed during early embryogenesis are maintained precisely to ensure functional stability throughout the life of an animal. However, preexisting synaptic connections can change in response to various environmental and growth-related signals. The proposed research focuses on elucidating the molecular genetic mechanisms controlling synapse formation and remodeling in the nematode Caenorhabditis elegans. C. elegans is an excellent organism to study events occurring at synapses because of the simple anatomy and powerful genetics. Six motor neurons are chosen as experimental objects because they remodel their synaptic patterns during development. In young larvae, they receive synaptic inputs from the dorsal side of the animal and innervate ventral body muscles; in older larvae and adults, they receive synaptic inputs from the ventral side and innervate dorsal body muscles. A fluorescent marker is used to observe the synapses of these neurons in living animals. Three sets of experiments will be carried out: first, to examine how the timing of the synaptic remodeling is regulated; second, to identify other genes involved in this process in genetic screens for mutants that exhibit defects in the synaptic patterns of these neurons; third, to analyze the function of the syd-1 gene, which appears to regulate synapse formation in the C. elegans nervous system. Training in neurobiology is an integral part of an undergraduate biology education. Neurobiology at University of California at Santa Cruz is underdeveloped because of the shortage in faculty with research interests in neurobiology. The education goal in this proposal is to establish a coherent undergraduate curriculum in neurobiology and to incorporate the proposed research into undergraduate education. Studies using simple organisms have been proven to be invaluable to the understanding of mechanisms that are evolutionarily conserved throughout the animal kingdom. This work shall shed light on the understanding of other kinds of neural plasticity, such as those involved in learning, memory, adaptation, and aging.
