Developmental and environmental control of adipose tissue

White adipose tissue (AT) serves as a critical energy reservoir during undernutrition and undergoes pathologic expansion and inflammation in obesity. Although alterations in the intestinal microbiome are known to influence AT growth, metabolism, and inflammatory tone, the mechanisms linking microbial signals to adipose biology remain poorly defined, due in part to the limited capacity for dynamic, in vivo imaging and quantitative analysis in rodent models. To overcome these barriers and extend our work on vertebrate energy balance, we established the zebrafish as a tractable system for defining developmental and environmental determinants of adipose tissue biology. We developed methods to visualize adipose depots in vivo, demonstrated extensive structural and functional homology between zebrafish and mammalian AT, and generated the first comprehensive anatomic atlas of zebrafish AT depots. To enable rigorous phenotypic analysis, we created a quantitative framework incorporating linear discriminant analysis to resolve adiposity traits across genetic and environmental conditions. Leveraging this platform, we identified Plexin D1 (PLXND1) as a conserved regulator of body fat distribution and insulin sensitivity in both zebrafish and humans, thereby validating the model and establishing a cross-species genetic pathway linking adipose patterning to metabolic health.