Meeting Abstract

10.2  Wednesday, Jan. 4  Is chytridiomycosis a stress induced syndrome? PETERSON, J.D.*; STEFFEN, J.; POHLMAN, W.; MCDONALD, M.; APPEL, A.; COBINE, P.; ROLLINS-SMITH, L.; MENDONCA, M.T.; Auburn University; Troy University, Montgomery; Penn State, Erie; Auburn University; Auburn University; Auburn University; Auburn University; Vanderbilt University; Auburn University

Chytridiomycosis, a disease caused by Batrachochytrium dendrobatidis (Bd), has contributed to amphibian population declines the world over, but its pathogenesis is still unclear. Infection disrupts cutaneous sodium channels, which leads to hyponatremia and cardiac failure. However, infection also has unexplained effects on appetite, skin shedding, and white blood cell (WBC) numbers. Corticosterone (CORT) may be the biochemical connection between these disparate effects, because it regulates ion homeostasis and can also influence appetite, skin shedding, and WBCs. During a lab outbreak as well as a controlled infection of Bd in Litoria caerulea, we compared frogs that were symptomatic for chytridiomycosis to asymptomatic as well as control frogs and determined that symptomatic frogs contained elevated baseline CORT, decreased plasma sodium and potassium, and WBC profiles that paralleled those observed following CORT treatment in other studies. Symptomatic frogs also had decreased body condition and elevated metabolic rates compared to asymptomatic frogs, as predicted by the metabolic effects of CORT in other vertebrates. Prior to becoming symptomatic, we also observed effects on appetite, body mass, and the presence of shed skin associated with these frogs. Collectively, these results suggest that elevated baseline CORT is associated with chytridiomycosis. Therefore, some of the ill effects observed during chytridiomycosis, such as alterations in WBC numbers and elevated metabolic rate, may be a secondary effect of elevated baseline CORT, not Bd.