Understanding the role of Proteins and Carbohydrates in driving the feeding behavior of Drosophila melanogaster

Abstract

In delving into Drosophila nutrition, through my master’s thesis, I have explored the roles of proteins and carbohydrates in driving the Drosophila feeding behavior. Previous studies and extant literature have looked at this aspect but in the light of factors like age, sex, and lifespan. Moreover, they primarily use liquid diets, not reflecting the fruit flies' natural solid food intake. My master’s thesis aims to fill this gap, establishing a foundation for measuring protein and carbohydrate intake in a solid food assay setup. Using the DIETS assay, I played around and made various ratios of P:C diets to track fly consumption in order to address this. A major challenge in this was to get the evaporation values for all of these diets to the permissible comparable levels and thus made for a major part of my thesis. This problem was overcome by doing repeated rounds of evaporation standardization with various parameters like humidity, distance from the food cup etc, for all these different diets and has been highlighted and summarized in the troubleshooting section of this master’s thesis. While existing literature leans toward the "Protein leverage hypothesis," my results consistently highlight carbohydrates, not proteins, being maintained across diverse diets. This contradicts the norm and led to our speculative "Carbohydrate leverage hypothesis." Results from two-cup-two-choice and CAFE assays and several other results from our lab align with this perspective, suggesting carbohydrates drive Drosophila feeding behavior. The thesis concludes by exploring the discussions, implications, reasons, and arguments for this novel hypothesis.