Lipidomic profiles of Drosophila melanogaster and cactophilic fly species: models of human metabolic diseases.

The metabolic syndrome (MetS) is associated with serious diseases and represents an important threat for global public health. The common fruit fly (Drosophila melanogaster) has served as a model organism to study physiological processes of the MetS, because central metabolic pathways are conserved among species, and because the flies are easy to cultivate in a laboratory. In nature, D. melanogaster is a fruit generalist, feeding on diets rich in simple carbohydrates. Other Drosophilids, however, have specialized on distinct resources. Drosophila mojavensis, for example, is endemic to the Sonoran Desert, where it feeds on necrotic cacti which are low in carbohydrates. Its close relative Drosophila arizonae is cactophilic as well, but is also found breeding in fruits containing simple sugars. Previous studies have shown that high-sugar diets negatively affect the larval development of D. mojavensis and increase their triglyceride content, compared to D. melanogaster. More general metabolic profiles, in response to these different diets, however, have yet to be produced for any of the species. In addition, because D. arizonae appears somewhat intermediate between D. melanogaster and D. mojavensis in its development times and survival under the above mentioned diets, its general metabolic profiles are also of interest. Thus, in the present study we ask to what extent the general metabolism of these three different Drosophila species is affected by diets of distinct protein-sugar ratios. To obtain an un-biased view on possibly novel phenomena, we combined untargeted metabolomics with Random Forest data mining.