Meeting Abstract

P2.88  Thursday, Jan. 5  Gastrointestinal responses to aestivation for the aquatic salamander Amphiuma tridactylum SMITH, Matthew E.*; SECOR, Stephen M.; University of Alabama; University of Alabama

Aestivation is a natural-history strategy whereby organisms enter a state of dormancy to survive periodic or seasonal episodes of drought, high temperatures, and low food availability. Although the physiological responses to aestivation have been documented for lungfish, desert-dwelling anurans, and the aquatic salamander the siren, very little is known regarding the aestivation behavior and physiology of the amphiuma. Therefore, we examined the physiology and morphology of the three-toed amphiuma, Amphiuma tridactylum, in response to laboratory induced aestivation. We hypothesized that as an adaptive response to aestivation, amphiumas experience atrophy of their gastrointestinal tract and associated organs together with the downregulation of gastrointestinal function. These all serve to reduce their metabolic rate, thereby allowing them to survive long periods of dormancy while metabolizing endogenous energy stores. Here we present the rationale, methods, and findings of our study on examining the aestivation response of the amphiuma. To date, we have observed following three months of aestivation for the amphiuma: a 12% decrease in body mass, the shutdown of gastric acid production, no change in intestinal mass, no change in the cellular morphology of the epidermis or intestinal villi, and a 25% decrease in intestinal uptake of the amino acid proline. Given these relatively modest responses observed following three months of aestivation, it appears that for short bouts of aestivation that amphiuma do not need to dramatically alter tissue structure and function.