Summer Research Sheds Light on Sleep Cycles

Alexandra Raymond ’15 reports on her internship at Northwestern University.

This summer, I was fortunate enough to stay in Evanston, IL as an undergraduate researcher in the Allada Lab at Northwestern University. Being at the Allada lab during the summer was an incredible experience because I was able to get to know many other members of the lab that I had only seen in passing before. Since I was in the lab all day, during lunch breaks I would ask about another postdoctoral fellow’s research and talk to them about it, which was always very interesting and enlightening. In addition, I was able to attend and participate in weekly lab meetings, where researchers would present their experiments and data to the rest of the lab and then read and analyze the most recent scientific literature.

My research this summer focused on mapping out the circuitry that underlies the homeostatic regulation of sleep. I use fruit flies in these experiments, as fruit flies are genetically malleable and exhibit many of the core features of mammalian sleep, including homeostatic regulation. Specifically, I am testing whether known genetic modulators of sleep homeostasis act in discrete regions of the fly brain. There have been approximately 15 neuromodulators of sleep homeostasis identified in the fruit fly, but it is not yet known where in the fly brain these neuromodulators act on sleep homeostasis. I have been working with five genes (sleepless, creb2, insomniac, Ecdysone receptor, and dFmr1) to explore where the neuromodulators act. To do this, I am using the GAL4/UAS system, which is one of the most powerful tools for targeted gene expression.

In this transgenic expression system, two components are carried in separate lines, which allows for any molecule to be expressed anywhere in the fly brain, at any specified developmental time. The driver lines carry tissue-specific GAL4 expression (in this case, I used a driver called elavGAL4, which is pan-neuronal, so it expresses the specified gene in all types of neurons) while the modifier lines carry the coding sequence for the gene of interest under the control of UAS (upstream activating sequence) sites.

In my experiments, I would cross driver lines and modifier lines to create flies that expressed a gene of interest in all types of neurons. Crossing would involve maintaining the stocks of the modifier lines (transferring flies into new vials of food), collecting female elavGAL4 virgins, collecting male modifiers, placing 5 female elavGAL4 virgins and 5 male modifiers into a vial, and then collecting their progeny for sleep analysis.

To analyze sleep, I use a well-established method where flies are placed into individual glass tubes in the Drosophila activity monitoring system (DAM). Fly activity is measured by counting the number of infrared beam crossings per minute. Flies are sleep deprived using a mechanical device that rotates the flies, preventing sleep. The DAM then measures the rebound sleep and then the baseline sleep is compared to the rebound sleep.

I was responsible for running the entire experiment except for the analysis of the sleep data, which my postdoctoral supervisors do themselves. Over the course of the summer, I became a more efficient researcher, reorganized all the fly stocks, and created a new system to keep track of different aspects of this project (modifier fly stock levels, female elavGAL4 virgins available to cross, etc.) using Microsoft Excel, which has proved successful in minimizing errors and making the experiments run smoothly and on time.

This summer working in the Allada lab was an extremely valuable experience for me, as it allowed me to focus on my research and learn techniques that will be necessary for graduate school. I was able to spend a lot of time in the lab uninterrupted which allowed me to get to know other members of the lab and make connections that will undoubtedly serve me well in the future. After seeing my work ethic this summer, I got an offer from the two postdoctoral fellows that I worked with, Dae-Sung Hwangbo and Bart van Alphen, to write letters of recommendation for me for graduate school, which is amazing. In the fall quarter, I will be continuing my research on sleep homeostasis in the Allada lab as part of the research-for-credit program.

I would like to sincerely thank the Alumni Association Board for making this experience possible for me. It has opened many doors for me and will undoubtedly help me in the future when I apply to graduate school to pursue an advanced degree.