Salt and Water Homeostasis in Drosophila melanogaster

Background

Multicellular organisms maintain homeostasis of the internal milieu for optimal cellular functioning. This includes homeostasis of electrolyte concentrations, osmolality and pH. The kidney plays a central role in the maintenance of homeostasis through the regulation of transepithelial ion transport, the vectorial movement of water and ions across membranes. We study this process in the renal tubules of the fruit fly, Drosophila melanogaster. We have demonstrated a role for a chloride channel, bestrophin-1, in this process. We have also found that at the whole organism level, loss-of-function mutations in bestrophin-1 cause flies to die more quickly than wild-type when they are fed a high-salt diet. Ion transport occurs across different parts of the fly renal tubule, including the main segment and the lower segment, and also across the hindgut. Bestrophin-1 is expressed in all of these tissues. We would like to find out where bestrophin-1 is required in order for flies to survive on a high-salt diet. This will help us learn about ion transport processes important in iono- and osmoregulation. Perturbations of these processes in humans lead to electrolyte disorders, tonicity disorders and high or low blood pressure, which are frequent problems encountered in clinical practice that lead to patient morbidity and mortality.

Student Role

Our SPUR student will have a hands-on role in this project. First, the student will perform the necessary fly crosses to generate the flies needed for testing in experiments. The goal of this is to generate flies which have a mutation in bestrophin-1 throughout the whole fly, and express wild-type bestrophin-1 in specific tissues, such as the main or lower segment of the tubule, or the hindgut. Conversely, we have tools to knock down the bestrophin-1 gene in these specific tissues. Then, the student will study how quickly the bestrophin-1 mutants die on high-salt food compared to controls. This is a straightforward assay that was successfully performed by undergraduates in a physiology class last year. The student may also test whether bestrophin-1 mutants eat and drink normally. Data will be analyzed using GraphPad Prism and the student will be guided through statistical analysis and data presentation.

Outcomes

Our SPUR student will learn about Drosophila genetics and the physiology of salt and water handling in both insects and mammals. The student will have the opportunity to plan and perform experiments, and analyze and present data. Together with data we already have in the lab on this project, we expect the results of these experiments to be published, and the student may wish to get involved in preparing figures for publication and in manuscript preparation (although this may happen after the summer is over). This is a great opportunity to get a hands-on feel for a basic science lab, and is appropriate for students who are considering a future career in a life sciences setting, graduate school in the biological sciences, medical school, or simply want to try out research.

Aylin Rodan
Assistant Professor

Internal Medicine
College of Medicine
Molecular Biology Program

My mentoring philosophy is to get students as involved as possible in everything going on in the lab. That is the best way to learn! Our SPUR student will be paired with a more experienced lab member in order to get lots of hands-on help, and everyone in our lab is generally friendly, helpful and willing to teach. We have lab meeting every Friday, and the student will have the opportunity to learn about what others in the lab are working on, and also to share their progress on the project. The student will also have regular meetings with me (the PI) to discuss their progress. I am also happy to discuss students' shorter and longer term goals (for example, graduate or medical school) and help guide them as they try to reach these goals. Additional mentoring activities will be tailored to these goals.