ROTH, E.B.*; SECOR, S.M.; University of Alabama, Tuscaloosa; University of Alabama, Tuscaloosa: Proximate mechanisms regulating intestinal performance for the Burmese python, Python molurus

Burmese pythons (Python molurus) widely regulate intestinal performance with each meal. Within 24 hours after feeding, intestinal mass doubles as nutrient transport rates increase by 5 to 20-fold. Elevated intestinal performance is maintained during digestion and upon its completion, intestinal performance is severely downregulated. Unknown are the underlying mechanisms responsible for regulating the python�s intestinal performance. Potential mechanisms include an increase in transporter activities, and increase in transporter densities, or an increase in luminal surface area. We hypothesize that intestinal performance is a function of surface area, given the 4-fold increase in microvillus length after feeding. This is suggestive from the correlation between intestinal function and microvillar surface area. In addition, we have found that if the postfeeding lengthening of the microvilli is inhibited by cytochalasin D, nutrient uptake is decreased by 40%. We propose three models to explain the rapid postfeeding growth of the python�s intestinal microvilli: (1) rapid actin polymerization and membrane construction from cytoplasmic stores; (2) microvilli construction from components rapidly synthesized, and, (3) the raising of intact microvilli from the cytoplasm. Of these models, we hypothesize that the first is responsible for the growth of the python�s microvilli. Evidence for this model stems from the post-feeding expression and position of several microvillar proteins.