Analysis of Dendrite Patterning Dynamics in Novel Self-Avoidance Mutant. Marvin Nayan, Jay Parrish. Dept. of Biology, University of Washington, Seattle, WA.

   Dendrite morphology is a hallmark of neuronal cell-type and plays an important role in neuronal function. Underscoring the relationship between dendrite form and neuronal function, defects in the spatial arrangement of dendrites are a pathological correlate of numerous diseases of cognition. Using genetic screens, we have been dissecting genetic pathways that underlie the formation and maintenance of dendritic arbors? Here we report on a novel mutation that is defective in dendrite self-avoidance. Using time-lapse confocal microscopy and quantitative analysis, we found that this mutation leads to progressive, late-onset dendrite branching defects and intermingling of dendrites in Class IV dendritic arborization (ddaC) neurons. Early stages of dendrite patterning are not affected by this mutant, suggesting that the mutant perturbs a genetic program that normally ensures maintenance of dendrite self-avoidance. We are currently investigating how broadly this mutation affects dendrite self-avoidance by assaying defects in other classes of sensory neurons. Finally, we have mapped the mutant to a small interval on Chromosome III and will report on our progress in identifying the gene(s) affected by this mutation.