John F. Rawls, Ph.D.

Research

We are using the zebrafish (Danio rerio) to investigate the mechanisms underlying host-microbe interactions in the vertebrate gut. We have developed methods for rearing germ-free zebrafish, and used those techniques to identify host responses to the gut microbiota that have been evolutionarily conserved between fish and mammals. To generate simplified experimental platforms, we have also identified individual bacterial members of the gut microbiota that elicit conserved host responses upon colonization of germ-free zebrafish. Current research projects in our lab are focused on the following areas: innate immune responses to the gut microbiota, microbial regulation of host nutrient metabolism, and environmental regulation of adipogenesis.

As an Innovation Fund investigator, Rawls and his lab are teaming up with the lab of Steven A. Farber, Ph.D., to investigate how dietary nutrients, such as fats, alter the body’s ability to sense glucose in the gut. Rawls, who has done extensive research on host-microbe interactions, and Farber, who studies lipid metabolism, both use zebrafish as a model for their respective work, and they recently demonstrated that a high-fat meal lowers the ability of certain cells in the intestines to sense glucose, a process that is dependent on a particular type of bacteria. Glucose sensing is important for proper metabolic function, particularly the release of insulin from pancreatic beta cells. By conducting novel imaging and genetic studies in zebrafish, Rawls and Farber hope to determine the mechanism by which a high-fat diet interferes with intestinal cells’ ability to sense glucose and identify the intestinal microbes that are involved in the process. This work could offer additional information on the role microbes play in nutrition and provide new strategies to combat metabolic disorders such as diabetes and obesity.