Summary
A bioRxiv preprint maps labeled nutrients across adult female fruit flies, finding distinct patterns of metabolism in different body regions. In flies with gut tumors, alanine’s contribution to malate increased, and reducing gut alanine uptake lowered tumor burden.
A bioRxiv preprint describes a way to map nutrient use across the adult fruit fly without relying only on measurements from dissected tissues. The researchers combined whole-fly mass-spectrometry imaging, stable-isotope tracing and flux modeling to chart labeled metabolites across the body. They report that nutrient use differs by region, and that alanine metabolism changes in flies with gut tumors.
The analysis covered 68 tracer-fed Oregon-R female flies. It mapped 81 metabolites across eight annotated regions, including muscle, fat body, gut and nervous system, using 187,709 imaging pixels. The work is a preprint and reports findings in flies.
Following nutrients across the fly
Stable-isotope tracing uses forms of nutrients whose atoms can be distinguished by their mass. By tracking those atoms into other molecules, researchers can see which nutrients contribute to particular metabolic products. Mass-spectrometry imaging adds spatial information, while flux modeling estimates relative activity in metabolic pathways.
That spatial detail matters because a whole organism is not metabolically uniform. The authors note that previous work in adult fruit flies has mostly measured metabolism in dissected tissues, limiting the ability to see where activity occurs in the intact animal. Their approach links metabolite labeling to annotated body regions instead.
Different regions use nutrients differently
Glucose labeling and the fitted relative fluxes indicated higher glycolytic and tricarboxylic acid (TCA) cycle turnover in thoracic muscle than in abdominal fat body. Glycolysis breaks down glucose, while the TCA cycle is a central pathway cells use to extract energy and process carbon-containing molecules.
The patterns also differed by nutrient. Proline labeled the nervous system and eye, while glutamine labeled the abdominal reproductive system and gut. Alanine carried glucose-derived carbon through the hemolymph, the fly’s circulatory fluid, and transferred nitrogen into glutamate. These results show how tracing both nutrient-derived carbon and nitrogen can reveal distinct routes through the body.
Alanine use changes in gut tumors
In flies with gut tumors driven by the yorkie gene, alanine’s contribution to malate rose in the gut and abdomen. The researchers also report that reducing gut alanine uptake lowered tumor burden in these flies. Together, these findings connect a spatially resolved metabolic change with tumor growth in this fly model.
The study provides a framework for examining how tissues share and use nutrients, and how those patterns shift in a disease model. Its measurements come from adult female fruit flies, including a specific genetically driven gut-tumor model; the findings therefore describe metabolism in those experimental settings rather than establishing how nutrient use works in human tumors.