Heads and thoraxes of 10 d old female Drosophila melanogaster flies

The aim of this study was to use unbiased transcriptomic analysis to characterize new traits that may explain differences in longevity between short- and long-lived wild-type backgrounds of Drosophila melanogaster – Dahomey and Oregon R, respectively. For the experiment we chose young flies (10 days old) to capture the difference in basal gene expression related to the genotype rather than to age-dependent functional decline. As a source for RNA extraction we used heads and thoraxes (combined) as tissues the most sensitive to aging. The expression of 3939 genes was changed (nearly 26% of the transcriptome, p-value < 0.05), with 1970 being upregulated and 1969 genes being downregulated in the Dahomey background compared to Oregon R. We found that young short-lived Dahomey flies have the traits previously associated with shorten lifespan such as increased lipo-oxidative stress, increased Tor signaling and loss of proteostasis and mitochondrial complex I activity. We hypothesized that all these characteristics are caused by an increase in octopamine signaling that promotes foraging behavior even under laboratory conditions where nutrients are in excess. Our results highlight the importance of controlling the genetic background in aging studies as well as interrogating several different pathways before making conclusions about what causes differences in longevity between different groups or individuals.