Meeting Abstract
Coincident with its out-of-Africa expansion, Drosophila also evolved capacity to live in ethanol-rich vineyards and orchards. However, sensitivity to alcohol varies among individuals within and across populations of Drosophila. Multiple genes and their interactions with the environment (G X E) underlie alcohol related fitness phenotypes. Furthermore, the bioenergetic responses to ethanol by mitochondrial oxidative phosphorylation (OXPHOS) require proteins from both the mitochondrial and nuclear genomes, creating the potential for inter-genomic gene-by gene (G X G, or epistasis) interactions to underlie variation in alcohol-induced phenotypes. Not surprisingly, therefore, the genetic bases of a complex trait like ethanol metabolism remains poorly understood. Here, we addressed this question by using Drosophila larvae with different nuclear and mitochondrial genetic backgrounds reared under developmental ethanol exposure. We demonstrated that ethanol induces oxidative stress, mitochondrial dysfunction (elevated basal respiration, proton leak, depolarization of mitochondrial membranes), and compromised whole-organism energy read-out (reduced lipid reserves and decreased pupation height). Thus, altered energy metabolism resulted in increased energy expenditure for basal maintenance in Drosophila larvae; but these effects were largely modulated by the underlying genetic architecture in both the natural isolates as well as in the larvae with mito-nuclear genotypes. These data correlate genetic variation with ethanol induced physiological trade-offs and provide comparative insights about how genetic variation among different ecotypes could potentially allow them to adapt to dynamic ethanol environments.
