Normalized NMR integration values from the metabolomic analysis of Drosophila larvae extracts from 2 genotypes at 3 time points.

We measured the metabolites related to energy production using 1H nuclear magnetic resonance spectroscopy (NMR). No alterations in the levels of carbohydrate stores or free amino acids were found between control and Sema1ai animals, corroborating the notion that the main metabolic changes are in the lipid metabolism. The exception is the glycolytic amino acid alanine (elevated in Sema1ai animals), confirming alterations in glycolysis. The levels of the ß-alanine amino acid are markedly reduced in 256 h AEL or 10.5-day-old Sema1ai animals, probably indicating muscle degeneration in the severely obese larvae that is consistent with the deteriorated state and reduced movement of the 10-day-old (256 hours) mutant larvae. Gluconeogenesis is stimulated by high lactate, and the concentration of lactate is higher in Sema1ai larvae than controls, though the difference is not statistically significant. Glycolysis is stimulated by glucose and inhibited by citrate, an early intermediate of the citric acid cycle. The increased citrate levels in the 10.5-day-old Sema1ai larvae suggest that glycolysis is lower at this age, consistent with the increased level of glucose in the severely obese larvae. The fact that both gluconeogenesis and glycolysis pathways are simultaneously enhanced in Sema1ai larvae support the hypothesis that the animals defecting in adiposity signaling are in a state of perceived energy insufficiency despite having sufficient energy stored.