Circadian rhythm and the three scientists who discovered it
Earlier this month, the winners of the Nobel Prize in Physiology or Medicine were announced. Jeffrey C. Hall, Michael Rosbash, and Michael W. Young received the award for “their discoveries of molecular mechanisms controlling the circadian rhythm.” But what does that mean?
To start, the circadian rhythm is roughly a 24-hour cycle all living beings possess. The plants outside of your window to the butterflies migrating for winter all have a built-in biological clock. You can thank the birds’ circadian rhythm for singing at 5 am outside of your bedroom window. (Or does that only happen to me?) In humans, like other animals, the circadian rhythm determines our sleeping and feeding patterns.
Before the three laureates discovered what makes our biological clock tick (yes, pun intended), scientists believed plants and animals were reacting to the sunlight. Now, because of their work we have scientific evidence proving we are anticipating the light.
The circadian rhythm is controlled by the period gene which undergoes its oscillation. During the day, the gene has low levels of the per protein and elevated levels at night. The per protein facilitates the oscillation cycle the period gene undergoes.
All three laureates independently isolated the period gene that controls daily oscillation in fruit flies (Drosophila melanogaster) and found the per protein to be present in eye tissue, salivary glands, ovaries, and brain neurons.
After isolating the period gene, they wanted to understand how it oscillates and sustain this cycle. Hall and Rosbash hypothesised the per protein was most abundant at night and diminished during the day in the cells. Young found how the protein entered the nucleus by discovering a second gene called timeless which possessed the protein, tim. Per and tim bounded together to travel inside the nucleus and stop the process of creating more per.
In short, to stop the cell’s nucleus in creating per in the period gene, per needs to block the gene, but he can only do that with his trusty sidekick tim by his side.
The laureates’ work set a baseline for future research in circadian rhythms.
Scientists discovered various health problems could be linked to night shift work from the disruption of their circadian rhythm from increased risk of diabetes to an increased risk of cancer. Other research found that jet lag has similar effects to the body that night shift work has. While the increased risk of diabetes and cancer are long-term effects, more immediate results include the amount of effectiveness medicine may have on an individual.
With an increase in “blue light” emitted from screens, scientists researched how that can affect our circadian rhythm. Similar to night shift workers, individuals playing on their computer or phone just before bed does not help balance their circadian rhythm.
Blue light and night shift work suppresses the hormone melatonin and prolongs the release of per proteins because of the short-wavelength light screen emit. These short-wavelengths are called blue light because of where they land on the colour bar.
Studying animals’ circadian rhythm is a growing field and the work Hall, Rosbash, and Young have put into researching it has opened the door to many more scientists.