Day 3: Morning Larks, Night Owls & the Rhythms that link our Daily Lives to Earth
With sleep being a necessity for every student, Prof. Carrie Partch shared her lecture, “Morning Larks, Night Owls, and the Rhythms that Link Our Daily Lives to Earth,” diving into the circadian rhythms of living organisms. We learned how our body follows the sleeping schedule regulated by light and melatonin. She continued with the scientific background of sleep, introducing how gene networks and suprachiasmatic nuclei signal to our eyes. Further heightening our curiosity, Prof. Partch introduced human circadian clocks and chronotypes, early and late, based on age. Ending with genetic variation, she taught us about how humans can be genetically night owls or morning larks.
Circadian rhythms align physiology and behavior 24 hours daily, causing living organisms to live according to the light and dark cycle. They control the timing of our daily lives, with melatonin directing the times we sleep and awaken. Prof. Partch pinpointed blue light as the most sensitive,causing humans to recognize it as daylight. Since cell phones create blue light, which suppresses the release of melatonin, she advised us to avoid looking at our phones at night.
Going deeper into the circadian rhythms, she shared how our body works according to sleep and waking times. From the lowest body temperature, highest body temperature, best concentration, and best time for coffee, we understood how our body functions according to our sleep schedule. Specifically, we found that 2 p.m.is the most effective time to drink coffee, and around 10 p.m. is the best studying time since we are most concentrated during that time.
We were surprised to learn that Earth’s animal and plant species have intriguingly different circadian clocks despite exposure to equal lengths of daylight. Although the Syrian hamster has a perfect 24-hour circadian clock, humans have circadian rhythms that last roughly 24 hour and 11 minutes. While answering our questions, she also introduced an interesting fact that blind people can maintain the human circadian cycle through special photoreceptors. Diving deeper into the science behind sleep, we became fascinated with the story of sleep.
We continued with a discussion of chronotypes, or default sleeping times. Early chronotypes, also known as morning larks, go to bed early and tend to have shorter circadian rhythms. Most teenagers, however, belong to the late chronotype group, the night owls. Prof. Partch described the shifting of chronotypes with age and sympathized with the mass of teenagers with early-morning zero periods.
Wrapping up with a mutation of the human circadian gene, Prof. Partch introduced an incorrectly spliced mutant of the CRY11 gene that successively delayed melatonin release at night, making people with the mutation typically sleep at 3 a.m. Prof. Partch ended the lecture with a discussion on the ideal sleep and encouraged us to head outside to receive plentiful sunlight during the day.
- Joanna Rhim (Cluster 2)
Circadian rhythms align physiology and behavior 24 hours daily, causing living organisms to live according to the light and dark cycle. They control the timing of our daily lives, with melatonin directing the times we sleep and awaken. Prof. Partch pinpointed blue light as the most sensitive,causing humans to recognize it as daylight. Since cell phones create blue light, which suppresses the release of melatonin, she advised us to avoid looking at our phones at night.
Going deeper into the circadian rhythms, she shared how our body works according to sleep and waking times. From the lowest body temperature, highest body temperature, best concentration, and best time for coffee, we understood how our body functions according to our sleep schedule. Specifically, we found that 2 p.m.is the most effective time to drink coffee, and around 10 p.m. is the best studying time since we are most concentrated during that time.
We were surprised to learn that Earth’s animal and plant species have intriguingly different circadian clocks despite exposure to equal lengths of daylight. Although the Syrian hamster has a perfect 24-hour circadian clock, humans have circadian rhythms that last roughly 24 hour and 11 minutes. While answering our questions, she also introduced an interesting fact that blind people can maintain the human circadian cycle through special photoreceptors. Diving deeper into the science behind sleep, we became fascinated with the story of sleep.
We continued with a discussion of chronotypes, or default sleeping times. Early chronotypes, also known as morning larks, go to bed early and tend to have shorter circadian rhythms. Most teenagers, however, belong to the late chronotype group, the night owls. Prof. Partch described the shifting of chronotypes with age and sympathized with the mass of teenagers with early-morning zero periods.
Wrapping up with a mutation of the human circadian gene, Prof. Partch introduced an incorrectly spliced mutant of the CRY11 gene that successively delayed melatonin release at night, making people with the mutation typically sleep at 3 a.m. Prof. Partch ended the lecture with a discussion on the ideal sleep and encouraged us to head outside to receive plentiful sunlight during the day.
- Joanna Rhim (Cluster 2)
Day 4: On the Toxicity of Our Environment
and Its Persistent Effects
and Its Persistent Effects
Cluster 7’s Prof. Peter Weiss-Penzias and Prof. Carlos Diaz-Castillo delivered our ninth Discovery Lecture, “On the Toxicity of Our Environment and Its Persistent Effects,” which covered exposomes and mercury in food webs. Prof. Weiss covered the mercury in food webs while Prof. Castillo covered exposomes. Learning about both topics, many of us found interest in either exposomes and mercury and asked many puzzling questions from mercury detoxification via hair growth to TBT-dependent changes in DNA methylation. While lecturing, the professors gave many examples, which ranged from World War 2 to fatal methylmercury, the culprit behind the death of an unsuspecting Dartmouth College chemist 15 years ago. The examples were also accompanied with many visuals.
Starting off with exposomes, Prof. Castillo talked about nature versus nurture through the Dutch famine birth cohort study. The post-World War 2 Dutch famine saw upwards of 20,000 deaths due to malnourishment and disease. The Dutch famine birth cohort study that Prof. Castillo talked about discussed mothers affected by famine. Even though malnourishment is not a genetic ailment, the offspring had low birth weights, as well as additional health complications later in life. The offspring, who couldn’t get a fresh start, established that organismal traits are determined not only by genetics but also by the environment and the delicate interplay between the two.
From Prof. Castillo’s discussion about the exposomes, the talk transitioned to mercury in food webs. While learning about mercury, I also found the differences between elemental and organomercury fascinating. Prof. Weiss delved into the chemical and physical properties of mercury: most interestingly, its low melting point and volatile nature. Even though they are made of similar material, they are like polar opposites. He then talked about his lab work, experiments on how methylmercury gets into coastal fog, and his misty bike ride to work that sparked his interest in the presence of mercury in fog. Although safely dispersed in fog in extremely low concentrations, he mentioned that when concentrated, organomercury killed an unlucky Dartmouth chemist despite her latex gloves. I know for sure that I would love to have nothing to do with organomercury ever. Organomercury, more commonly methylmercury, accumulates in the fat tissue of fish, which lends to its biomagnification. This means that regardless of the initially low concentrations of methylmercury in water, organisms higher up in the trophic chain, like beluga whales, swordfish, and tuna, run the risk of storing dangerously high levels of mercury. Their predators, often humans, risk mercury poisoning. Furthermore, the mercury in our hair can determine how much quantity is in our bodies. Even mentioning a fun fact, Prof. Weiss said “the solution to pollution is dilution.”
The professors did a wonderful job explaining about mercury and exposomes and undoubtedly inspired many in the audience to explore environmental sciences with a deeper understanding of the toxins around us. I look forward to next week’s discovery lectures!
- Evelyn Zhao (Cluster 7)
Starting off with exposomes, Prof. Castillo talked about nature versus nurture through the Dutch famine birth cohort study. The post-World War 2 Dutch famine saw upwards of 20,000 deaths due to malnourishment and disease. The Dutch famine birth cohort study that Prof. Castillo talked about discussed mothers affected by famine. Even though malnourishment is not a genetic ailment, the offspring had low birth weights, as well as additional health complications later in life. The offspring, who couldn’t get a fresh start, established that organismal traits are determined not only by genetics but also by the environment and the delicate interplay between the two.
From Prof. Castillo’s discussion about the exposomes, the talk transitioned to mercury in food webs. While learning about mercury, I also found the differences between elemental and organomercury fascinating. Prof. Weiss delved into the chemical and physical properties of mercury: most interestingly, its low melting point and volatile nature. Even though they are made of similar material, they are like polar opposites. He then talked about his lab work, experiments on how methylmercury gets into coastal fog, and his misty bike ride to work that sparked his interest in the presence of mercury in fog. Although safely dispersed in fog in extremely low concentrations, he mentioned that when concentrated, organomercury killed an unlucky Dartmouth chemist despite her latex gloves. I know for sure that I would love to have nothing to do with organomercury ever. Organomercury, more commonly methylmercury, accumulates in the fat tissue of fish, which lends to its biomagnification. This means that regardless of the initially low concentrations of methylmercury in water, organisms higher up in the trophic chain, like beluga whales, swordfish, and tuna, run the risk of storing dangerously high levels of mercury. Their predators, often humans, risk mercury poisoning. Furthermore, the mercury in our hair can determine how much quantity is in our bodies. Even mentioning a fun fact, Prof. Weiss said “the solution to pollution is dilution.”
The professors did a wonderful job explaining about mercury and exposomes and undoubtedly inspired many in the audience to explore environmental sciences with a deeper understanding of the toxins around us. I look forward to next week’s discovery lectures!
- Evelyn Zhao (Cluster 7)