Drosophila embryos spatially sort their nutrient stores to facilitate their utilization

Abstract

Animal embryos are provisioned by their mothers with a diverse nutrient supply critical for development. In Drosophila, the three most abundant nutrients (triglycerides, proteins, and glycogen) are sequestered in distinct storage structures, lipid droplets (LDs), yolk vesicles (YVs) and glycogen granules (GGs). Using transmission electron microscopy as well as live and fixed-sample fluorescence imaging, we find that all three storage structures are dispersed throughout the egg but are then spatially allocated to distinct tissues by gastrulation: LDs largely to the peripheral epithelium, YVs and GGs to the central yolk cell. To confound the embryo’s ability to sort its nutrients, we employ mutants in Jabba and Mauve to generate LD:GG or LD:YV compound structures. In these mutants, LDs are missorted to the yolk cell and their turnover is delayed. Our observations demonstrate dramatic spatial nutrient sorting in early embryos and provide the first evidence for its functional importance.

Metabolic rewiring in fat-depletedDrosophilareveals triglyceride:glycogen crosstalk and identifies cDIP as a new regulator of energy metabolism

“…Strikingly, periodic acid-Schiff (PAS) staining revealed significantly concentrated glycogen deposits in FASN1 FB-RNAi FBs compared to controls, and biochemical measurements confirmed a remarkable >20-fold glycogen increase in FASN1 FB-RNAi FBs (Fig 2E,F). Increased glycogen granules were also detected in FASN1 FB-RNAi FB by imaging Glycogenin-YFP, as glycogenin functions as a primer for glycogen polymerization 42 (SFig 2E). QPCR analyses showed elevated expression of other key enzymes involved in glycogen synthesis (glycogenesis) and glycogen breakdown (glycogenolysis) (SFig 2F).…”