A mild heat stress increases resistance to heat of dFOXO Drosophila melanogaster mutants but less in wild-type flies

While severe stresses have deleterious effects, mild stresses can have beneficial effects called hormetic effects. This study observed survival time at 37.5 °C and at 13–16 days of age of wild-type Drosophila melanogaster flies and dFOXO mutants, after they were subjected to 5 or 10 min daily at 37.5 °C for 5 days starting at 5 days of age. This mild stress increased survival time of the mutants, this effect being nearly not observed in wild-type flies. Previous studies showed that another mild stress, the cold, can increase survival time to heat of wild-type flies, but not of dFOXO mutants, while hypergravity increased survival time of mutants but not of wild-type flies. Therefore, three mild stresses, cold, hypergravity, and heat can increase resistance to heat but the pathways mediating this effect are seemingly different, as cold does not increase resistance in dFOXO mutants but increases it in wild-type flies, while hypergravity and heat have opposite effects. It appears that dFOXO may be needed or not to observe hormetic effects. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10522-021-09914-1.