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Show GENETIC ANALYSIS OF A NOVEL SIGNALING PATHWAY IN CAENHORABDITIS ELEGANS Phillip Chaffin, Barton Reyes, [Maureen Peters, Erik Jorgensen) Department of Biology, University of Utah Behavioral rhythms underlie many important biological processes including hormone secretion, heartbeat and circadian rhythms. We are using genetic techniques to study a behavioral rhythm in the soil dwelling nematode, Caenhorabditis elegans (C. elegans). Every fifty seconds the worm initiates a coordinated three-step sequence of muscle contractions that aid in the expulsion of the nematode's waste products. The cycle begins with the posterior body wall muscle contractions (pBoc), which force the gut contents to the anterior section of the intestine. This step is followed a few seconds later by the anterior body wall muscle contractions (aBoc), which aids in concentrating the gut contents near the anus. aBoc is immediately followed by the enteric muscle contraction (Emc), which forces some of the gut contents out of the animal. This series of muscle contractions is controlled by a novel signaling mechanism. Both the periodicity and execution of the posterior body contractions are controlled by a non-neuronal cell type, the intestine. In vivo calcium imaging studies revealed a correlation of intestinal calcium spiking in the most posterior intestine and the initiation of the posterior body contraction (Dal Santo et al., 1999). The last two steps of the cycle, the aBoc and Emc, are controlled by neurons. To determine how intestinal calcium signaling con-trols the activity of these neurons, we are studying mutants that are defective in both aBoc and Emc (aex) mutants. Two alleles of a novel strong aex mutant have been identified and character-ized. Assays of neurotransmission indicate a modest decrease in neurotransmission in the mutant. To determine whether neu- ronal development is normal we are currently examining neuro- nal outgrowth using a neuronal fluorescent protein. In an effort to determine the molecular lesion causing these phenotypes, we have mapped the mutation to the far-left arm of chromosome1I. Uncovering the molecular identity of the mutant will give further insight into this novel signaling pathway. References Dal Santo, P., Logan, M. A., Chisholm, A.D., Jorgensen, E.M. (1999). The Inositol Trisphosphate Receptor Regulates a 50-Second Be-havioral Rhythm in C. elegans. Cell 98, 757-767. Phil Chaffin Biology |
