E&E Fall 2021 Seminar Series:
Dr. Karen Peralta Martinez
University of Pittsburgh - Kohl Lab
"Understanding the flexibility of the mammalian gut physiology and gut microbiota in response to diet"
The vertebrate gastrointestinal tract is a flexible system that is highly responsive to internal (host) and external (environment) dynamics. Optimal digestion theory has been used to model expected changes in gut structure and function to maintain maximal digestive efficiency under changing food supply. For instance, digestive efficiency typically decreases with increasing amounts of indigestible fiber in the diet. However, animals can remodel the gut, often displaying larger and longer GI tracts when on high fiber diets to maintain nutrient uptake as non-digestible materials slowly travel down the gut and encounter greater absorptive surface area, demonstrating unique physiological flexibility. A detailed understanding of how physiological processes across levels of biological organization optimize function remains one of the "Grand Challenges" in animal physiology. In addition, our understanding of this plasticity, both biomedically relevant and in the context of ecology and evolution, has largely been studied without considering the gut microbiome – the diverse microbial communities that perform vital physiological and metabolic functions. Diet induces changes in the form and function of the gastrointestinal tract, and the microbial community within. Here, we studied four closely related rodent species with different feeding strategies, Microtus montanus (herbivore), Peromyscus leucopus (omnivore), Peromyscus maniculatus (omnivore), and Onychomys torridus (insectivore). During two distinct feeding trials, we fed individuals different fiber diets (chitin- and cellulose-containing diets) varying in nutrient content. We hypothesized that animals fed fiber containing diets will exhibit drastic changes in the structure and morphology of the gut compared to animals fed control diets. We observed unique responses in the mass and size of the digestive tract in response fiber-containing diets. Digestibility and gut microbiome structure and function also varied across species and as an effect of diet. Finally, we conducted path analysis to integrate our data and understand what physiological changes underly the variability in digestibility. Path analysis supported our idea that fiber is a main driver of plasticity followed by internal cellular processes. These data will enhance our understanding of optimal digestion theory and identify physiological changes that are most important for maximizing digestive performance. I plan to integrate molecular, cellular, and physiological assays, as well as microbial metagenomics, to disentangle the role of the host from that of the microbiome in the phenotypic flexibility of the gastrointestinal tract. This integrative approach will help us understand the importance of phenotypic flexibility in animal’s ecology and evolution.
Wednesday, October 27th, 2021
A219B Langley Hall
12:00 PM