Gene Expression Analysis of Fat Body of Drosophila melnaogaster subjected to Dietary restriction for certain time points

Dietary restriction is a nutritional intervention that consistently increases life span in animals. To identify alternative, more acceptable nutritional regimes that nevertheless extend life span, we used the fruit fly Drosophila melanogaster as a model. We tested if weekly recurring nutritional regimes composed of phases of ad libitum feeding and dietary restriction can increase life span. Short periods of dietary restriction (up to 2 days) followed by longer ad libitum phases increased life span only marginally, whereas regimes comprising longer contiguous periods (3 days and more) became clearly positive, reaching similar life span extensions as those seen if dietary restriction was applied persistently. Female flies were substantially more responsive to these interventions than males. The finding that a minimal period of 3-4 days of dietary restriction is required to induce robust life span extensions was mirrored by the observation that substantial physiological and transcriptional changes occurred in a similar temporal pattern. Moreover, these dietary restriction induced changes were also detectable after switching to ad libitum feeding. Among the physiological changes induced by these phases of dietary restriction, a reduced metabolic rate and a substantial and long-lasting reduction in insulin signaling were most compelling. Age associated molecular signatures comprising mechanisms that reduce insulin signaling showed up after longer periods of dietary restriction in the fly’s fat body, thus showing how molecular alterations transduce into life span related physiological changes. 6 groups of samples types were included in the experiment: manually isolated fat bodies from a) females subjected to dietary restriction for 1d, b) subjected to dietary restriction for 3d, c) subjected to dietary restriction for 7d and the matching controls subjected to control diets.