Project Summary Organs of the human body rely on complex integration of multiple neuronal circuits in order to maintain homeostasis. For example, the heart must respond to internal and external stimuli and produce sufficient blood flow to meet environmental demands. Glia play critical roles to support nervous system function but are also indispensable for establishment of appropriate circuit structure and physiology. Our lab recently identified a cell type in the heart with many similarities to astroglia populations found elsewhere in the body. This cell type, which we termed cardiac nexus glia, is present as the heart is being formed and is critical for establishment of heart rhythm. Ablation of these glia causes cardiac arrhythmia and ventricular fibrillation, both serious physiological conditions. This project uses the zebrafish animal model to investigate the developmental ontogeny and morphological characteristics of cardiac nexus glia in the developing hearts of living animals (Aim 1). Additionally, it probes the functional relationship between these glia and cardiomyocytes and their roles in modulating heart rate and rhythm (Aim 2). The results of these experiments will contribute crucial detail to our understanding of the multi-faceted roles of glia in the peripheral nervous system and provide important and specific insight about cardiac nexus glia function in heart development and disease. This research will be undertaken in a supportive and collaborative laboratory environment within the Biological Sciences Department at Notre Dame University. It will rely on expertise from staff of the Center for Zebrafish Research and the Integrated Imaging Facility. In addition to the development of bench skills and technical expertise inherent to this project, the applicant will also hone teaching, mentoring, and management skills that will be critical for her future success as a PI running her own research group at a primarily undergraduate institution.