Tag Archives: Circadian Rhythms

The Circadian Rhythm’s Role in the Kidney
Emilio Roig
Junior, Microbiology & Cell Science
University of Florida
2019 STRIDE Fellow

My Research Project

According to the Centers for Disease Control and Prevention (CDC), one out of every three people in U.S. is affected by high blood pressure, which is also known as hypertension. Hypertension is a serious health concern because it significantly increases the risk of heart disease, stroke and kidney damage. In healthy individuals, blood pressure dips at night, allowing the heart to experience a period of time in which it is not under significant stress. However, some individuals have been diagnosed with what is termed as “non-dipping” hypertension in which blood pressure is constantly elevated, putting them at greater risk for cardiovascular disease. The fluctuation of blood pressure between night and day is regulated by our body’s circadian clock. The circadian clock is the body’s intrinsic time keeper, telling us when to wake up, when to eat and when to sleep. At the molecular level, every cell in the body also contains its own clock, including kidney cells. To better understand the circadian contribution to blood pressure, my research project for the summer of 2019 has been focused on studying the role of Per1, is one of the main circadian regulators in the kidney. The kidneys are responsible for filtering blood and are directly involved in the control of blood pressure. By removing the circadian rhythm gene Per1 from a specific region of the kidney, its contribution to blood pressure can be determined by comparing it to normal individuals that have the Per1 gene. Our goal for this project was to demonstrate why some individuals develop hypertension or fail don’t experience the normal drop in blood pressure at rest. Understanding the mechanism behind why some people develop “non-dipping” hypertension could potentially lead to better cures and therapies, thereby lowering the risk of cardiovascular disease.

Realities of Research

Even though this was not my first time working in a lab, it was the first time that I began working full time. Five days a week, my day began at 9 a.m. and would finish at 5p.m. However, sometimes I would find myself in deep thought about my project beyond those hours. I learned quickly that research is taking a step out into the unknown, meaning taking time to truly understand the complexities of the body’s physiology. Often,the results of my experiments were unexpected and generated more questions than answers. Other times the experiments would simply fail; the first Western Blot I ever attempted was an adventure. By spending a large majority of time in the lab, I have gained a new appreciation for researchers. Being a researcher takes persistence, creativity and an open mind.

Life as a Scientist

My sheer curiosity about the world is what originally drove me to become involved in research as soon as I began college. The American Physiological Society gave me the opportunity to develop as a scientist, immersing me in the vast complexities of scientific phenomena. Science can often be frustrating because things don’t always go as planned. But the moment new discoveries are made, every failure along the way becomes irrelevant. Persistence took on a new meaning for me the moment I had begun trying my own experiments, and that’s the beauty of science. When something finally is successful, it can open a whole world of possibilities.

Emilio Roig is a junior majoring in microbiology and cell science at the University of Florida (UF), located in the city of Gainesville. He is a Short-Term Research Education Program to Increase Diversity in Health-Related Research (STRIDE) Fellow working in Dr. Michelle Gumz’s lab at the UF College of Medicine. His summer of research was funded by the American Physiological Society and through a grant from the National Heart, Lung, and Blood Institute (Grant #1 R25 HL115473-01). After graduation, Emilio plans to pursue a career in medicine so that he can fulfill his dream of preventing and curing disease.

Does Light Pollution Cause Heart Disease in Mice?

Light levels at night have significantly increased since industrialization1. During this same period of time, there has also been an increase in the incidence of heart disease. Previous studies have shown that light pollution, which is experimentally called dim light at night (DLAN), disrupts circadian rhythms1-2 and increases the likelihood for developing obesity2-3, but its connection to cardiovascular disease is not known2, 4. My experiments this summer determined if DLAN increased atherosclerosis the mouse aorta. I also analyzed eating behavior to confirm previous studies that DLAN causes a higher proportion of eating to occur during the day than normal2. My research is part of a larger project that focuses on disruption of daily rhythms and heart disease. The project will hopefully give new insight into possible causes of the global increase in heart disease. A greater understanding can lead to prevention and treatment of heart disease.

Dr. Pendergast often reminds everyone in our lab that results will not always support the hypothesis. However, she also says that unexpected or negative results are still relevant and can lead to new experiments. The first couple of rounds of my experiment were mainly just working out kinks in the experimental protocol such as adjusting light levels to set up the DLAN conditions. I also learned new techniques including genotyping using PCR, mouse care, analyzing eating behavior, and aorta dissection and cleaning. Preliminary eating behavior data show that exposure to DLAN may lead to eating at the wrong time of day in mice. The atherosclerosis data obtained so far has shown high levels of atherosclerosis in male mice exposed to DLAN, and normal levels in female mice. Although the sample number is still low, the results do seem to suggest that exposure to DLAN increases atherosclerosis in male mice.

Since I am doing research with mice, mouse care is an everyday task in my research experience. Using mice for experiments is exciting because they provide data simply by being housed in their light-tight boxes with food and water. Getting results and sharing them with the lab is one of my favorite parts of research because it always leads to a discussion of what the results mean and the future directions of the experiment. However, the analysis of this data, such as watching hours of videos of eating behavior, is not the most exciting process. Being part of a research lab is interesting because of the daily discoveries about animal physiology, which lead to thoughtful discussions about how they relate to everyday life. Overall, research has been a valuable experience for me that has strengthened my time management, leadership, and problem-solving skills.


  1. Fonken, L. K.; Aubrecht, T. G.; Melendez-Fernandez, O. H.; Weil, Z. M.; Nelson, R. J. Dim light at night disrupts molecular circadian rhythms and increases body weight. Journal of biological rhythms 28(4), 262-71, 2013.
  2. Fonken, L. K.; Workman, J. L.; Walton, J. C.; Weil, Z. M.; Morris, J. S.; Haim, A.; Nelson, R. J. Light at night increases body mass by shifting the time of food intake. Proceedings of the National Academy of Sciences of the United States of America, 107(43), 18664-9, 2010.
  3. McFadden, E.; Jones, M. E.; Schoemaker, M. J.; Ashworth, A.; Swerdlow, A. J. The relationship between obesity and exposure to light at night: cross-sectional analyses of over 100,000 women in the Breakthrough Generations Study. American journal of epidemiology, 180(3), 245-50, 2014.
  4. Morris, C. J.; Purvis, T. E.; Hu, K.; Scheer, F. A. Circadian misalignment increases cardiovascular disease risk factors in humans. Proceedings of the National Academy of Sciences of the United States of America, 113(10), E1402-11, 2016.
Robert Wendroth is a senior at the University of Kentucky in Lexington, KY, majoring in Chemistry and Biology. He is working at the University of Kentucky in Dr. Julie Pendergast’s lab. He is a 2017 UGSRF fellow, which is funded by the American Physiological Society. After graduation, Robert plans to attend medical school and become a physician who also performs research.