(By Dan Moorhead and Alex Lupolt – Brandauer lab)
Circadian Rhythm, or someone’s “sleep/wake cycle”, is a complex cycle that coordinates our resting and active states throughout a particular day with environmental cues such as light or lack thereof. Metabolism, muscle recovery, body temperature, and many other biological functions show characteristic changes throughout the course of the day. The word “circadian” combines two Latin words, circa, “around/about” and diem, “day.” So how long does one sleep/wake cycle take? About a day.
Throughout evolutionary history, organisms have been continuously exposed to a daily cycling of light and darkness, day and night. It is of no surprise then that many biological processes exhibit daily oscillations that are synchronized with a roughly 24-hour light and dark cycle. In fact, most organisms possess a common molecular machine that governs cellular and tissue circadian rhythmicity through a transcription-translation feedback loop—a likely evolutionary consequence of countless sunrises and sunsets. Humans are photosensitive organisms that are governed by endogenous cellular fluctuations which are regulated by both a central nervous system clock and a molecular clock believed to be present in all cells of the body. Since our light and dark cycles play an important role in regulating proper biological function, disruptions in circadian rhythms (jet-lag, night-shift work, and the movement of daily life indoors) can have deleterious consequences to human health (seasonal affective disorder, psychological disorders, metabolic disorders, cancer, etc.).
In our lab, we work to the rhythms of alternative rock, country music, and no matter what the task, it seems that it takes about a day to accomplish anything. Dissections and snap freezing, aliquotting and pulverizing, Bradford protein assays, homogenizing, and Western Blots. Take any two of these, and if done correctly, the answer to the question “How long will this take?”—Circa Diem. We work rhythmically and timely, as a unit, everything is precise, just like one’s circadian rhythm. But it is ironic, because as we as ponder the effects of bright light on physiology we sit in a somewhat dimly lit, windowless lab, experimenting on the circadian clocks of mice, all while probably messing up our own. In fact, in an attempt to investigate tissue-specific oscillations of molecular clock machinery in order to determine which tissues are more sensitive to circadian disruptions, we will be disrupting our own circadian cycles with a 24 hour experiment, collecting data at 4-hour intervals. This scientific all-nighter is sure to test the power of our internal clocks (and how many Red Bulls we can drink).