Meeting Abstract

P3.95  Tuesday, Jan. 6  The effect of temperature and reproductive condition on snake complement activity GRAHAM, Sean P*; SEWELL, Leanne M; Auburn University; Auburn University grahasp@auburn.edu

Most vertebrate physiological systems (e.g., the endocrine system) are highly conserved; however, the extent to which the immune system exhibits this conservatism is not as well known. Vertebrate complementan innate immune response involved in the incapacitation of pathogenshas been suggested to show higher diversity in ectotherms than more traditional model organisms, and therefore investigations in fishes, amphibians, and reptiles may prove fruitful. We studied complement activity in a snake (the cottonmouth, Agkistrodon piscivorus) indirectly using a bacterial killing assay, and tested the following hypotheses: 1) complement activity (percent plasma bacterial killing) would vary according to in vitro incubation temperature, predicting optimal temperature for killing capacity to be similar to the snakes documented preferred body temperature (e.g., ~ 24C). 2) Complement activity would vary among treatment groups of snakes exhibiting different reproductive conditions. Specifically, we predicted that pregnant snakes would have reduced bacterial killing capacity, consistent with studies of mammals which have described reduced complement and inflammatory responses in pregnant females. We discovered a statistically significant positive correlation between bacterial killing capacity and incubation temperature, suggesting a higher temperature for optimal complement performance in this snake than its own preferred temperature usually allows. In addition, we found significantly reduced complement killing capacity in pregnant females relative to non-pregnant females. Together, these results illustrate interesting ecological trends in this component of the snake immune system, and underscore the importance of considering body temperature when conducting ecoimmunological studies.