The
unc-13 gene has been determined to affect the nervous system of C. elegans. In
unc-13 mutants, there is slow, irregular pharyngeal pumping, uncoordinated movement, and an insensitivity to cholinesterase inhibitors with an accumulation of acetylcholine. The Unc-13 protein contains a diacylglycerol binding domain, consisting of cysteine repeats and a calcium, phospholipid, and cytoskeletal element binding domain analogous to those of protein kinase C. Electron micrograph reconstruction of the nervous system of two
unc-13 mutant alleles reveals abnormal gap junctions and chemical synapses between many interneurons, including AVA, AVB, and AVD. Also, there is abnormal axonal morphology of the AS2 motor neuron. Sequence elements of
unc-13 indicate that it is a novel component of a signal transduction pathway. Mutant characteristics suggest it is involved in the development of the nervous system and it's function. Our current goal is to resolve the expression pattern of
unc-13. Due to the phenotype we believe that it is expressed mainly in neurons, but possibly not in all neurons. The 5' end of the
unc-13 mRNA has been identified and used to locate the region containing the
unc-13 promoter. The promoter region has been subcloned into a reporter gene construct. Preliminary data using F1 progeny shows staining which appears to be restricted to neurons in the ventral nerve cord, the nerve ring and tail ganglia. In addition, we have generated polyclonal antisera to two portions of the Unc-13 protein. The antisera will be used for western analysis of wild type and
unc-13 mutant nematodes and for immunohistochemistry in order to confirm the cellular staining observed with the reporter gene.