A temporal allocation of amino acid resources ensures fitness and body allometry in Drosophila

Organisms have evolved strategies to store resources and overcome periods of low or no nutrient access, including transient shortages or longer non-feeding developmental transitions. Holometabolous insects like Drosophila represent an attractive model to study resource allocation during development because they alternate feeding and non-feeding periods. Amino acids are essential components for tissue growth and renewal, but the strategies used for their storage remain largely unexplored. Here, we characterize the molecular mechanisms for the temporal production, accumulation, and use of specific storage proteins called hexamerins, and demonstrate their role in ensuring tissue formation and adult fitness. Moreover, we show that preventing hexamerin stores enhances the growth of early-developing organs while compromising the emergence of late-forming ones, consequently altering body allometry. [Display omitted] •Nutritional and developmental cues control storage protein expression by fat cells•Fat body protein 1 promotes the reuptake of hexamerins into the fat body•The formation of amino acid stores during the larval stage limits organ growth•Altering amino acid storage affects adult fitness and body proportions Valzania et al. genetically decipher the pathways by which amino acids are stored in the form of hexamerin complexes at the end of larval development and later used during metamorphosis. They show that proper temporal allocation of amino acid stores is required to maintain allometry between early-forming and late-forming organs.