Galactose alters early-life development and exerts sex-specific nutritional programming effects on lifespan in Drosophila melanogaster

Background Nutritional programming by early-life nutrition exerts long-lasting effects on later-life health. In mammals, galactose, as a component of the milk sugar lactose, is consumed during lactation. Mouse studies suggest that prolonged postweaning galactose consumption improves later-life metabolic health, but it is unclear whether these benefits translate into increased lifespan. The fruit fly Drosophila melanogaster is an attractive model for studying programming effects on lifespan due to its relatively short lifespan. Methods Drosophila larvae were fed on either a galactose- or standard glucose-based diet. Upon eclosion, adult male and female flies were switched to either a standard or a high-glucose obesogenic diet. We assayed larval developmental time and pupal metabolism, followed by adult body weight, triacylglycerol (TAG) levels, and lifespan. Results In early-life, galactose consumption significantly prolonged larval development time, increased the pupal volume, reduced the pupal mitochondrial mass, and increased the energy expenditure of pupae in a body-weight-dependent manner. In adults fed a glucose diet, early-life galactose consumption significantly increased body weight, decreased whole-body TAG content, and reduced survival rate only in female flies, leaving males unaffected. These programming effects were absent when the adult flies were fed a high-glucose obesogenic diet. Conclusion We newly show that dietary galactose has significant effects on early-life development of Drosophila , with sexual dimorphism in nutritional programming effects, which depend on the later-life diet.