Biology (B.S.B.)

Document Type and Release Option

Thesis (open access)

Faculty Mentor

Dr. Zachary R. Stahlschmidt


Following a meal, an animal can exhibit dramatic shifts in its physiology that can result in rapid growth of the gut and heart, as well as a massive (>40-fold) increase in metabolic rate associated with the energetic costs of processing the meal. However, little is known about the effects of digestion on an important physiological trait: immune function. Thus, I tested the following competing hypotheses. First, digesting animals may upregulate their immune systems due to increased microbial exposure from ingested food. This hypothesis predicts that animals will exhibit greater immune function during digestion. Second, digesting animals may downregulate their immune systems to devote energy to the breakdown of food. This hypothesis predicts that animals will exhibit lower immune function during digestion. I tested my hypotheses by measuring two assays of innate immunity (the chief mechanism of host defense across taxa) on the blood plasma of corn snakes (Pantherophis guttatus) during and after meal digestion. I specifically measured hemoagglutination (antibody-mediated agglutination of foreign red blood cells) and hemolysis (complement-mediated lysis of foreign red blood cells) at two time points (1 and 7 day[s] post-feeding [dpf] to reflect digestive and nondigestive states, respectively). Hemoagglutination was higher at 1 dpf in support of my first hypothesis. Furthermore, females had higher lysis than males. In sum, I demonstrate the effects of digestive state on innate immune function, further highlighting the myriad physiological responses that occur in response to food intake and digestion.