Meeting Abstract
24.3 Friday, Jan. 4 Modest regulation of gastrointestinal morphology and function for the frequently feeding diamondback watersnake, Nerodia rhombifer COX, C. L.*; SECOR, S.M.; University of Texas, Arlington; The University of Alabama, Tuscaloosa clcox@uta.edu
Infrequently feeding snakes (boas, pythons, and vipers) widely regulate gastrointestinal performance with each meal as an apparent adaptive response to long periods of fasting. Therefore, frequently feeding snakes are predicted to exhibit more modest changes in gastrointestinal function and morphology with feeding and fasting. To explore this prediction, we assessed for the frequently feeding diamondback watersnake (Nerodia rhombifer) the postprandial response in organ mass, gastric pepsin activity, pancreatic trypsin activity, as well as aminopeptidase-N activity and l-leucine, l-proline, and d-glucose uptake for three regions of the small intestine. Watersnakes were fed catfish meals weighing 25% of their body mass, and tissues were collected from fasted snakes, and snakes 0.5, 1, 2, and 4 days after feeding. Tissues were weighed, enzyme activities were measured using standard colorimetric methods, and intestinal nutrient uptake rates were quantified using the everted sleeve technique. We found the stomach, pancreas and small intestine not to vary significantly in mass after feeding. Whereas pepsin activity did not vary significantly after feeding, trypsin activity decreased by 20% upon feeding, returning to fasted levels 4 days postfeeding. Intestinal aminopeptidase-N activity increases significantly (5 to 8-fold) throughout the small intestine with feeding, returning towards fasting levels by day 4 of digestion. In contrast, there was no postprandial increase in the uptake of any of the measured nutrients for each region of the small intestine. As an adaptive correlate to their frequent feeding habits, diamondback watersnakes, in general, do not widely regulate gastrointestinal function and morphology as observed for infrequently feeding snakes.
