Resistance to stress as a function of age in transgenic Drosophila melanogaster overexpressing Hsp70

This study investigated the resistance to stress as a function of age in Drosophila melanogaster overexpressing Hsp70. The resistances to starvation, paraquat, and cold in flies from 1 to 7 week-old have been measured. The line carrying the insertion vector without the transgenes is more resistant to starvation and cold than the parental and transgenic lines. In contrast, transgenic flies carrying extra-copies of hsp70 are more resistant to paraquat, however this is due to an especially high resistance in two age groups compared to all the other groups. I showed that exposure to a mild heat shock does not increase starvation resistance, slightly increases paraquat resistance, and strongly increases cold resistance. The transgenic flies expressing Hsp70 at higher levels after the heat shock do not exhibit enhanced stress resistance compared to control lines expressing less Hsp70 after the heat shock. The lack of effect of a mild heat shock on starvation and paraquat resistance is not due to a disappearance of the effect with age, since no effect is observed at any age. In contrast, when an effect of Hsp70 induction is observed as on cold resistance, this effect is still observed in old flies.