Fruit flies have eight identified Drosophila insulin-like peptides (DILPs) that are involved in the regulation of carbohydrate concentrations in hemolymph as well as in accumulation of storage metabolites. In the present study, we investigated diet-dependent roles of DILPs encoded by the genes dilp1–5, and dilp7 in the regulation of insect appetite, food choice, accumulation of triglycerides, glycogen, glucose, and trehalose in fruit fly bodies and carbohydrates in hemolymph. We have found that the wild type and the mutant lines demonstrate compensatory feeding for carbohydrates. However, mutants on dilp2,3, dilp3, dilp5, and dilp7 showed higher consumption of proteins on high yeast diets. To evaluate metabolic differences between studied lines on different diets we applied response surface methodology. High nutrient diets led to a moderate increase in concentration of glucose in hemolymph of the wild type flies. Mutations on dilp genes changed this pattern. We have revealed that the dilp2 mutation led to a drop in glycogen levels independently on diet, lack of dilp3 led to dramatic increase in circulating trehalose and glycogen levels, especially at low protein consumption. Lack of dilp5 led to decreased levels of glycogen and triglycerides on all diets, whereas knockout on dilp7 caused increase in glycogen levels and simultaneous decrease in triglyceride levels at low protein consumption. Fruit fly appetite was influenced by dilp3 and dilp7 genes. Our data contribute to the understanding of Drosophila as a model for further studies of metabolic diseases and may serve as a guide for uncovering the evolution of metabolic regulatory pathways.

Insulin‐like peptides (ILPs) belong to the insulin superfamily and act as hormones, neuromediators, and growth factors during the post‐embryonic life‐cycle stages of insects. These peptides are encoded by different genes in various species. In the genus Drosophila, eight peptides are known, seven of which are likely to bind the Drosophila insulin receptor, whereas DILP8 is a known ligand of the Lgr3 receptor. Binding of DILPs 1‐7 to receptors leads to activation of intracellular proteins related to the conserved insulin/IGF (insulin‐like growth factors) signaling pathway. The insulin pathway acts within a complex physiological regulatory network involved in the coordination of development, growth, behavior, metabolism, lifespan, and cognitive functions in insects. The current review summarizes recent data about the structure and function of ILPs in fruit flies. The role of environmental factors and genetic manipulations in modulating the functions of DILPs and their association with lifespan and metabolism of Drosophila are assessed. Further investigation and identification of pharmacological or biotechnological interventions that may decrease insulin/IGF signaling could be a highly promising approach for extension of human health span and longevity.

No abstract

No abstract

Nutrition affects various life-history traits. We used fruit flies Drosophila melanogaster to determine whether life-history traits, particularly life span and metabolism, are affected by dietary sucrose content. We fed flies by four different diets containing constant yeast concentration and increasing amounts of sugar ranged from 1% to 20%. We found that low sucrose diet increases female lifespan. We also showed, that low dietary sucrose maximized malate dehydrogenase, aspartate aminotransferase activity in males and lactate dehydrogenase activity in females. In addition, dietary carbohydrate has a considerable impact on urea level, suggesting that dietary carbohydrate impacts overall metabolism. Our findings revealed the influence of dietary sugar on metabolic enzymes activities, indicating an existence of optimal nutritional conditions for prolongevity phenotype and confirming an important impact of dietary sugar on life-history traits.

No abstract

Mitochondrial alternative NADH dehydrogenase (aNDH) was found to extend lifespan when expressed in the fruit fly. We have found that fruit flies expressing aNDH from Ciona intestinalis (NDX) had 17-71% lifespan prolongation on media with different protein-tocarbohydrate ratios except NDX-expressing males that had 19% shorter lifespan than controls on a high protein diet. NDX-expressing flies were more resistant to organic xenobiotics, 2,4-dichlorophenoxyacetic acid and alloxan, and inorganic toxicant potassium iodate, and partially to sodium molybdate treatments. On the other hand, NDX-expressing flies were more sensitive to catechol and sodium chromate. Enzymatic analysis showed that NDX-expressing males had higher glucose 6-phosphate dehydrogenase activity, whilst both sexes showed increased glutathione S-transferase activity.

Interventions such as caloric or dietary restriction extend lifespan in organisms spanning from yeast to primates. Despite its positive influence on longevity, dietary restriction has been found to negatively affect reproduction. Many studies have reported negative correlations between lifespan and reproductive characteristics (such as mating rate, fecundity, reproductive period, and others). Such correlation gives the appearance of a resource-based trade-off between these two life-history traits. Here, we have used nutritional geometry to confirm previous findings in flies that dietary macronutrient balance (protein-to-carbohydrate ratio, P:C) impacts both lifespan and reproduction, such that across a series of diets differing in P:C, maximum lifespan was observed at a lower P:C (1:8) than that which supported highest fecundity (1:1.5). We have then addressed the question whether variation among Drosophila melanogaster Meigen (Diptera: Drosophilidae) fruit flies in food intake and egg production within a single dietary treatment is negatively associated with within-diet variation in lifespan, as might be expected under a resource-based trade-off. There was no such association between intake rate, egg production, and longevity. We noted that the smaller sample sizes and smaller inter-individual variance apparent within -as compared to across -diet treatments may have weakened any signature of a trade-off between lifespan and reproduction. Thus, we conclude that, whereas dietary macronutrient ratio is a primary determinant of both reproduction and longevity, neither eating less nor laying fewer eggs per se predicted lifespan. This supports the view that there is not a simple quantitative resource-based trade-off between lifespan and reproduction, but rather these represent life-history traits with qualitatively different nutritional optima.