Mathematical Biology Seminar Katie Lynch, University of Utah, Wednesday, November 26, 2025 12:30 pm in LCB 222 Structure and Consequences of Gene Regulation in Vibrio Vulnificus Abstract: Vibrio vulnificus is a highly virulent marine bacteria which requires sufficient iron to grow; during infection, it primarily acquires iron from host hemoglobin. The gene regulatory networks (GRNs) involved in this process are important targets of study, yet their complexity and nonlinearity makes direct analytical study difficult. I will present a modeling approach that addresses this challenge by constructing simplified systems that retain key regulatory features and are tractable for bifurcation analysis. I will then use homotopy methods to transition from these simplified models to the biologically accurate model. This framework is applied to two GRNs for two key elements of iron acquisition via heme: a heme transporter (HupA) and hemolytic toxin (Vvh). This analysis reveals how regulatory feedback networks allow for dynamic responses to different environmental conditions. I will consider the broader implications of these GRNs in the context of infection by linking these cellular level regulatory processes to population level outcomes. In particular, the Vvh GRN helps determine the probability of colony establishment and proliferation in the early stages of infection. Overall, this multiscale perspective highlights how mathematical methods can clarify the structure and consequences of complex gene regulatory systems in bacteria.