Meeting Abstract

P3.103  Jan. 6  Acid is an immune disruptor in the acid resistant Green frog (Rana clamitans) VATNICK, I; BRODKIN, M; HOWANSKI, R*; OJO, B; SHANK, E; STASHEFSKI, L; Widener University; Widener University; Widener University; Widener University; Widener University; Widener University vatnick@pop1.science.widener.edu

Acid sensitivity varies among amphibian species and among populations within the same species. Wood frogs (R. sylvatica) and Green frogs (R. clamitans) are probably the most acid-resistant species among the ranids, can withstand very low pH levels, and are known to occur in bogs with an average pH ~4.0. Northern leopard frogs, are among the most acid sensitive ranids and suffer over 70% mortality within ten days of exposure to mild acidic conditions. We recently demonstrated, and previously presented in this meeting, that acid exposure diminishes the innate immune response of these frogs. Acidic pH suppressed an experimentally-induced inflammatory response associated with a reduction in peritoneal white blood cell number, phagocytic activity and increased colonization of the spleen by bacteria. We proposed a model for this effect and tested this model in Green frogs, an acid resistant species. We hypothesized that acid would have no effect on the innate immune response of R. clamitans and that they would experience low mortality as a result of acid exposure.Rana clamitans exposed to pH 5.5 experienced a net mortality of 7.5% compared to 70% in acid-sensitive R. pipiens, an observation that supports our hypothesis. To our surprise, acid-exposed R. clamitans experienced the same suppression of the inflammatory response as R. pipiens however; the number of bacteria colonizing the spleen of acid-exposed Green frogs was the same as the neutral pH-exposed control group. Based on these results we hypothesize that acid exposure either does not impair phagocytic activity of recruited WBC or the transit of bacteria across the gut epithelium of R. clamitans.