Body Metrics and the Gut Microbiome in Response to Macronutrient Limitation in the Zebrafish .

BACKGROUND

Healthy and predictable physiologic homeostasis is paramount in animal models for biomedical research. Proper macronutrient intake is an essential and controllable environmental factor for maintaining animal health and promoting experimental reproducibility.

OBJECTIVE AND METHODS

Evaluate reductions in dietary macronutrient composition on body weight metrics, composition, and gut microbiome in Danio rerio.

METHODS

D. rerio were fed reference diets deficient in either protein or lipid content for 14 weeks.

RESULTS

Diets of reduced-protein or reduced-fat resulted in lower weight gain than the standard reference diet in male and female . Females fed the reduced-protein diet had increased total body lipid, suggesting increased adiposity compared with females fed the standard reference diet. In contrast, females fed the reduced-fat diet had decreased total body lipid compared with females fed the standard reference diet. The microbial community in male and female fed the standard reference diet displayed high abundances of , Rhodobacteraceae, and . In contrast, spp. were dominant in male and female fed a reduced-protein diet, whereas displayed heightened abundance when fed the reduced-fat diet. Predicted functional metagenomics of microbial communities (PICRUSt2) revealed a 3- to 4-fold increase in the KEGG (Kyoto Encyclopedia of Genes and Genomes) functional category of steroid hormone biosynthesis in both male and female fed a reduced-protein diet. In contrast, an upregulation of secondary bile acid biosynthesis and synthesis and degradation of ketone bodies was concomitant with a downregulation in steroid hormone biosynthesis in females fed a reduced-fat diet.

CONCLUSIONS

These study outcomes provide insight into future investigations to understand nutrient requirements to optimize growth, reproductive, and health demographics to microbial populations and metabolism in the gut ecosystem. These evaluations are critical in understanding the maintenance of steady-state physiologic and metabolic homeostasis in . . 20xx;x:xx.