Our research uses multiple complementary approaches to understand how host-microbe interactions in the intestine regulate digestive physiology and energy balance. First, my lab uses genetic, gnotobiotic, and in vivo imaging approaches to determine how commensal microorganisms (microbiota) interact with vertebrate hosts to regulate their nutrition and immunity, as well as the mechanisms underlying assembly of intestinal microbial communities. We utilize the zebrafish as a host model in which host and microbial cells can be viewed and manipulated a transparent living vertebrate. We have pioneered the use of germ-free or gnotobiotic zebrafish to investigate the roles of microorganisms in vertebrate biology, and we are using these methods to investigate the bacterial signals and responsive host pathways that regulate host immunity, nutrition, and gene expression. Second, my laboratory is utilizing the zebrafish system to investigate mechanisms underlying the formation and function of adipose tissues. We have developed methods for in vivo imaging of zebrafish adipose tissue, and we are currently using these techniques to explore the developmental and environmental processes regulating adipose tissue growth and physiology. In both of these fields, we have effectively used zebrafish and mice to model key aspects of human physiology and pathophysiology, and to gain new insights into underlying mechanisms.