A Role for S6 Kinase and Serotonin in Postmating Dietary Switch and Balance of Nutrients in D. melanogaster

Abstract

Balancing intake of diverse nutrients is important for organismal growth, reproduction and survival. A shift in an organism’s optimal diet due to changes in nutritional requirements after developmental or environmental changes is referred to as dietary switch, and has been observed in several species [1]. We demonstrate that female D. melanogaster also undergo a dietary switch following mating that leads to an increased preference for yeast, the major source of protein in their diet. We demonstrate that S6 Kinase (S6K) and serotonin production are involved in the post-mating dietary switch. To further investigate the ability of D. melanogaster to balance nutrient intake, we examined the dietary preferences of adult flies following deprivation of yeast or sucrose in the diet. We observe that following conditioning on a diet deficient in either carbohydrates or yeast, D. melanogaster shows a strong preference for the deficient nutrient when permitted to choose its diet freely. Furthermore, flies with activated S6K or fed a serotonin precursor exhibit enhanced preference for yeast in this assay. Our results suggest that TOR signaling and serotonin may play an important role in maintaining nutrient balance in D. melanogaster. Hence, D. melanogaster can be used as a model organism to investigate the genetic basis for nutrient homeostasis which may contribute to our understanding of metabolic disorders such as obesity and diabetes [2].