• Studies assessing insulin signaling dependent neuronal morphology and novel animal sorting methods in a C. elegans model

      Hunter, Skyler C.; Bult-Ito, Abel; Taylor, Barbara; Podlutsky, Andrej; Vayndorf, Elena (2018-12)
      The purpose of this work is two-part. The primary goal of this thesis is to identify a list of significant target insulin-like peptides (ILPs) that influence the maintenance of neuronal morphology in an aged animal model of Caenorhabditis elegans (C. elegans) and determine whether or not morphological changes have bearing on neuronal function. The second goal is to address and devise a solution for a common laboratory difficulty encountered within the research community, difficulty maintaining large age-synchronous populations of the model organism, C. elegans. Chapter 1 discusses the importance of insulin signaling and how it pertains to the morphology of aging neurons. A reverse genetic screen was conducted to knockdown the expression of individual ILPs in a C. elegans model. The results identify a subfamily of ILPs that play significant roles in maintaining regular morphology of aging mechanosensory neurons. These data corroborate previously published work demonstrating that aberrant morphology of mechanosensory neurons does not directly influence their function and that these two parameters, morphology and function, can be uncoupled and considered mutually exclusive. Chapter 2 describes a main difficulty associated with using C. elegans as a model organism; the problem of maintaining a large age-synchronous population on solid media. To address this difficulty a novel piece of equipment, named the Caenorhabditis Sieve, and an accompanying methodology for its application, were created to mechanically sort and clean C. elegans. The use of this new device facilitates the implementation of assays with animals cultivated on solid media that are normally cost and resource prohibitive. Presented with the protocol for device construction and implementation, are standard experiments that were conducted to verify "proof of concept" of the tool's efficacy. The results demonstrate that the Caenorhabditis Sieve effectively transfers animals from one culture plate to the next in a manner that does not influence common markers of physiological stress; thus validating the sieve's use in future experiments among the research community, as well as highlighting the success of creating a cost-effective, efficient, fast, and simple process to mitigate difficulties and ease progress in research fields using small model organisms.
    • Transient spatiotemporal chaos in a Morris-Lecar neuronal ring network collapses to either the rest state or a traveling pulse

      Keplinger, Keegan (2012-12)
      Transient spatiotemporal dynamics exists in an electrically coupled Morris-Lecar neuronal ring network, a theoretical model of an axo-axonic gap junction network. The lifetime of spatiotemporal chaos was found to grow exponentially with network size. Transient dynamics regularly collapses from a chaotic state to either the resting potential or a traveling pulse, indicating the existence of a chaotic saddle. For special conditions, a chaotic attractor can arise in the Morris-Lecar network to which transient chaos can collapse. The short-term outcome of a Morris-Lecar ring network is determined as a function of perturbation configuration. Perturbing small clusters of nearby neurons in the network consistently induced chaos on a resting network. Perturbation on a chaotic network can induce collapse in the network, but transient chaos becomes more resistant to collapse by perturbation when greater external current is applied.