Regulation of intestinal dietary fat absorption is critical to maintaining energy balance. While intestinal microbiota clearly impact the host's energy balance, their role in intestinal absorption and extraintestinal metabolism of dietary fat is less clear. Using in vivo imaging of fluorescent fatty acid (FA) analogs delivered to gnotobiotic zebrafish hosts, we reveal that microbiota stimulate FA uptake and lipid droplet (LD) formation in the intestinal epithelium and liver. Microbiota increase epithelial LD number in a diet-dependent manner. The presence of food led to the intestinal enrichment of bacteria from the phylum Firmicutes. Diet-enriched Firmicutes and their products were sufficient to increase epithelial LD number, whereas LD size was increased by other bacterial types. Thus, different members of the intestinal microbiota promote FA absorption via distinct mechanisms. Diet-induced alterations in microbiota composition might influence fat absorption, providing mechanistic insight into how microbiota-diet interactions regulate host energy balance.

Lipids serve essential functions in cells as signaling molecules, membrane components, and sources of energy. Defects in lipid metabolism are implicated in a number of pandemic human diseases, including diabetes, obesity, and hypercholesterolemia. Many aspects of how fatty acids and cholesterol are absorbed and processed by intestinal cells remain unclear and present a hurdle to developing approaches for disease prevention and treatment. Numerous studies have shown that the zebrafish is an excellent model for vertebrate lipid metabolism. In this chapter, we review commercially available fluorescent lipids that can be deployed in live zebrafish to better understand lipid signaling and metabolism. In this chapter, we present criteria one should consider when selecting specific fluorescent lipids for the study of digestive physiology or lipid metabolism in larval zebrafish.

EZ2111h low-fat fed 6.5 dpf zebrafish larvae (low-fat cohort) Reads were mapped to the zebrafish genome Zv9 by Tophat2.Refseq annotation was used as known GTF.bedgrah files for visualization were generated by custom scripts.reads falling on genes were counted by custom scripts and differentially expressed genes were called by edgeR.Genome_build: Zv9Supplementary_files_format_and_content: bedgraph files for read densities along the genome (RPKM) were generated using custom scripts.

EZ1111h high-fat fed 6.5 dpf zebrafish larvae (high-fat cohort) Reads were mapped to the zebrafish genome Zv9 by Tophat2.Refseq annotation was used as known GTF.bedgrah files for visualization were generated by custom scripts.reads falling on genes were counted by custom scripts and differentially expressed genes were called by edgeR.Genome_build: Zv9Supplementary_files_format_and_content: bedgraph files for read densities along the genome (RPKM) were generated using custom scripts.

EZ2424h low-fat fed 6.5 dpf zebrafish larvae (low-fat cohort) Reads were mapped to the zebrafish genome Zv9 by Tophat2.Refseq annotation was used as known GTF.bedgrah files for visualization were generated by custom scripts.reads falling on genes were counted by custom scripts and differentially expressed genes were called by edgeR.Genome_build: Zv9Supplementary_files_format_and_content: bedgraph files for read densities along the genome (RPKM) were generated using custom scripts.

EZ2434h low-fat fed 6.5 dpf zebrafish larvae (low-fat cohort) Reads were mapped to the zebrafish genome Zv9 by Tophat2.Refseq annotation was used as known GTF.bedgrah files for visualization were generated by custom scripts.reads falling on genes were counted by custom scripts and differentially expressed genes were called by edgeR.Genome_build: Zv9Supplementary_files_format_and_content: bedgraph files for read densities along the genome (RPKM) were generated using custom scripts.

EZ2131h low-fat fed 6.5 dpf zebrafish larvae (low-fat cohort) Reads were mapped to the zebrafish genome Zv9 by Tophat2.Refseq annotation was used as known GTF.bedgrah files for visualization were generated by custom scripts.reads falling on genes were counted by custom scripts and differentially expressed genes were called by edgeR.Genome_build: Zv9Supplementary_files_format_and_content: bedgraph files for read densities along the genome (RPKM) were generated using custom scripts.

EZ1121h high-fat fed 6.5 dpf zebrafish larvae (high-fat cohort) Reads were mapped to the zebrafish genome Zv9 by Tophat2.Refseq annotation was used as known GTF.bedgrah files for visualization were generated by custom scripts.reads falling on genes were counted by custom scripts and differentially expressed genes were called by edgeR.Genome_build: Zv9Supplementary_files_format_and_content: bedgraph files for read densities along the genome (RPKM) were generated using custom scripts.