Meeting Abstract
Snakes exhibit a clear dichotomy in the capacity to regulate intestinal performance with each meal. Frequently-feeding species narrowly regulate intestinal function with feeding, whereas infrequently feeding species up and down regulate intestinal form and function with the start and finish of each meal. Driving this divergence in postprandial response is the lack of any change in microvillus length and absorptive surface for frequently-feeding snakes compared to the 3- to 5-fold lengthening of the microvilli and matched increases in intestinal function with feeding characteristic of infrequently-feeding species, a response that is reversed after digestion has completed. We are taking advantage of this distinct dichotomy in intestinal response and the link between form and function, to explore the signaling, cellular, and molecular mechanisms that underlie these divergent responses. Our comparative approach is allowing us to identify specific gene expression programs and regulatory pathways responsible for the synthesis, mobilization and insertion of microvillus and membrane proteins involved in the postprandial remodeling of the brushborder membrane for infrequently feeding snakes. Our results indicate that feeding activates pathways related to the nucleation and elongation of actin filaments for infrequently-feeding species. Centered in such pathways are the regulatory activities of Rho-family GTPases, known regulators of cytoskeleton dynamics and proposed regulators of microvillus formation. Although the phenotypic responses of the intestine are convergent among infrequently-feeding snake lineages, explored is whether the underlying molecular programs have evolved independently. Support provided by NSF IOS (SMS) 0466139 and IOS 1656138 (SMS & TAC).
