Nutrient sensing in the larval brain

• Applicant: Professorin Dr. Stefanie Schirmeier
• Subject Area: Molecular Biology and Physiology of Neurons and Glial Cells
• Term: from 2019 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 433556808

Understanding how neuronal circuits regulate the choice between different behaviors and, thus, choose one motor program to be executed over another, is a major goal in neuroscience. We will use feeding behavior in the Drosophila larva as a blueprint to study such decision-making. To ensure sufficient nutrient uptake, a hungry animal needs to find food and, if several food sources are available, choose the most nutritive, to feed from. Interestingly, Drosophila larvae and adults are able to choose nutritive carbohydrates over non-nutritive carbohydrates independently of their taste. It is known that a post-ingestive nutrient sensing mechanism is the basis for this ability. How the nutritive value of carbohydrates is measured, however, is not well understood. We propose to study post-ingestive nutrient sensing in detail. We will clarify the implication of Dh44- and Gr43a-positive neurons. We will investigate how these neurons sense carbohydrates, i.e. if they project into the periphery and sense circulating carbohydrates there or if they sense carbohydrate concentrations in the brain. Sensing in the brain could further be direct or indirect, meaning that other cells, e.g. glial cells could serve as a sensor and then signal to the respective neurons. We will study the connectivity of the two neuronal subtypes, analyze their projection pattern in detail to detect putative projections into the periphery, visualize close interactions with other cells like e.g. the blood-brain barrier forming cells and analyze their implication in post-ingestive nutrient sensing. Finally, we will use fluorescent nanosensors to study carbohydrate uptake and metabolism in the cell types of interest in detail. Together these approaches will allow to understand the molecular basis of post-ingestive nutrient sensing in the Drosophila larva.

• DFG Programme: Research Grants