Glow with the Flow: Visualizing bioelectric patterns and characterizing their relationship with connexins and morphogen signaling during axis determination in zebrafish

Bioelectrics is an emerging topic that investigates whether patterns of cellular membrane potential differ across tissues and whole organisms and could such distinctions regulate developmental processes. Mounting evidence suggests that bioelectric signaling could play important roles during regeneration. However, less attention has been paid to its involvement during early embryonic development, especially in vertebrates. Thus, our lab has begun to visualize and manipulate bioelectric patterns in developing zebrafish and determine their roles during formation of axial tissues during early embryogenesis. Cellular differentiation during axis determination in the early vertebrate embryo, is known to be induced by gradients of secreted morphogens such as, members of the Bone Morphogenic Protein, Fibroblast Growth Factor (FGF), and Nodal families. Preliminary studies from our lab using voltage sensitive dyes and transiently expressed genetically encoded voltage indicating proteins do suggest that distinct bioelectric patterns likely exist prior to the determination of cell fates along presumptive dorsal-ventral regions of the zebrafish embryo. To dissect whether bioelectrics may determine or mediate inductive effects of morphogens, we set out to manipulate tissue membrane potentials mediated by small molecules and ions that could flow across cells via Connexin gap junctions. Moreover, to monitor changes in bioelectric patterns over time, we are currently generating stable transgenic lines expressing different genetically-encoded voltage indicators. Summarizing our pharmacological and genetic strategies to interrogate specific modes of bioelectric signaling, we highlight an interesting overlap between phenotypes induced by manipulation of connexins and those regulated by FGF signaling during axis determination in zebrafish embryos. A poster deriving from Honors Theses in BIO and NSC, Special Studies, SURF, STRIDE, Beckman Scholars Program, McKinley Pre-Honors Fellowship, with Dr. Michael Barresi, Professor of Biological Sciences and Dr. Narendra Pathak, Laboratory Instructor in Neuroscience.