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Show 285 THE UNIVERSITY OF UTAH Determining the full anatomy of neurons is a key step in understanding how complex behav-ior is modulated. Little is known about neural connectivity and intracellular organization- specifically that of microtubules. Since studying synapses is hindered by the resolution limit of light microscopy, we have relied on transmission electron microscopy (TEM) and photo-ac-tivated localization microscopy (PALM). With the goal of better understanding neural anato-my, we have performed three separate experiments. First, we used a semi-automated method to reconstruct a portion of the ventral nerve cord in the nematode, Caenorhabiditis elegans. In this semi-automated reconstruction, computer programs detect, segment, and link neural membranes from hundreds of electron micrographs into a single three-dimensional volume. The connectivity was comparable to the manually generated connectivity map, suggest-ing the potential efficiency and accuracy of this procedure. Second, we performed a manual reconstruction to better understand the organization of microtubules and their relation to the synapse. Since microtubule continuity within neurons is not universally valid, we manu-ally reconstructed microtubules within ~200 electron micrographs. We found that almost all microtubules are discontinuous and do not extend throughout the entire neuron. Third, in order to confirm the discontinuity of microtubules, larger volumes must be studied. Thus, we used PALM to visualize individual microtubules along the ventral nerve cord. The reconstruc-tions created by these methods help us understand the physical organization of microtubules as well as the organization of neurons themselves. ULTRASTRUCTURAL ORGANIZATION OF C. ELEGANS NERVOUS SYSTEM Nikita Thomas (Erik Jorgensen) Department of Biology University of Utah honors college Nikita Thomas Erik Jorgensen |