Amita Sehgal facts for kids

Amita Sehgal is a top scientist who studies how our bodies work at a tiny, molecular level (a molecular biologist). She also studies our body clocks, which control when we sleep and wake up (a chronobiologist). She works at the Perelman School of Medicine at the University of Pennsylvania.

Dr. Sehgal helped discover important parts of the "clock" inside fruit flies. She also helped make fruit flies a key animal to study sleep. Her research today focuses on understanding the genes that control sleep. She also looks at how our body clocks affect other parts of our health.

About Amita Sehgal

Her Early Life and School

Amita Sehgal grew up in India. She earned her first science degree from Delhi University. Then she got her master's degree from Jawaharlal Nehru University in New Delhi.

In 1983, she started her PhD at Cornell University. Here, she studied how human brain cells grow. This work really sparked her interest in science. In 1988, she began working at Rockefeller University. This is where she first learned about circadian rhythms. These are the natural cycles our bodies follow, like sleeping and waking. She has been studying them ever since!

Key Discoveries

Dr. Sehgal has made many important discoveries about how living things keep time. Here are some of her major findings:

• 1994: She found a change (mutation) in fruit flies that affected their "timeless" gene.
• 1995: She identified the timeless gene itself. She showed that this gene's activity changes daily.
• 1996: She found that light can break down the timeless protein. This helps reset the body clock.
• 2000: She helped create a way to study sleep using Drosophila (fruit flies).
• 2001: She showed that a gene called neurofibromin 1 helps control the body clock in fruit flies.
• 2006: She discovered the jetlag gene. She showed that the JETLAG protein helps break down another protein called TIMELESS.
• 2006: She found that "mushroom bodies" in fruit flies' brains are important for sleep.
• 2008: She discovered the sleepless gene in fruit flies.
• 2014: She mapped brain pathways that connect the body clock to behavior.
• 2014: She found out why young animals sleep so much.
• 2018: She found a possible role for sleep in adult flies.
• 2018: She showed that the "blood brain barrier" changes throughout the day.
• 2019: She found a link between sleep and the body's defense system (immune system).

How Timeless and Period Genes Work

Amita Sehgal has greatly helped us understand the biological clock of Drosophila melanogaster (fruit flies). In 1994, Dr. Sehgal and her team found a change in the gene called timeless (TIM) in fruit flies.

The next year, they identified the TIM gene. They showed that TIM and another gene called PER have similar daily cycles of activity. They suggested that PER and TIM work together. They build up during the day. In the evening, they go into the cell's control center (the nucleus). There, they stop their own genes from being active. This model has been proven true over time. In 1996, Dr. Sehgal's lab showed that light can lower TIM levels. This helps reset the body's clock.

Neurofibromin 1 and Body Clocks

Neurofibromin 1 (NF1) is a gene that normally helps prevent tumors. Problems with this gene cause a condition called Neurofibromatosis Type 1. This disorder can cause tumors to grow along the spine.

In 2001, Dr. Sehgal and her team learned that some people with Neurofibromatosis type 1 also have trouble with their sleep. So, they looked at the body clocks of flies with a broken NF1 gene. They found that these flies also had messed-up body clocks. When they put a working NF1 gene back into the flies, their clocks became normal again. This showed that NF1 is part of the body clock system. They also found that in flies, NF1 works through a pathway called the MAP kinase pathway. This is the same pathway involved in Neurofibromatosis type 1 in humans.

Understanding Jetlag

In 2006, Dr. Sehgal and her team found a fruit fly that took a very long time to get used to new light and dark cycles. They named the gene causing this problem jetlag (jet). This gene makes a protein called JET. JET helps reset the fruit fly's clock.

The JET protein works with another protein called CRYPTOCHROME (CRY). Together, they help break down the TIMELESS (TIM) protein when there is light. This breakdown is very important for the clock to adjust to outside light cues, like when you travel to a new time zone.

Mushroom Bodies and Sleep

Mushroom bodies are parts of the brain in fruit flies. They are known to help with learning, memory, smell, and movement. In 2006, Dr. Sehgal and her team discovered that mushroom bodies also play a big role in controlling sleep in flies.

They used a special chemical to control how genes work in specific areas, like the mushroom bodies. They found that this part of the brain is very important for flies to sleep. We don't yet know the exact way mushroom bodies control sleep. But it might be that they help stop the brain from processing too much sensory information, which allows flies to fall asleep.

The Sleepless Gene

In 2008, Dr. Sehgal and her team found a gene in fruit flies called sleepless. When this gene was changed, the flies slept 80% less than normal flies. They also lived only half as long!

Dr. Sehgal and her team discovered that the SLEEPLESS protein controls certain channels in cells. These channels are important for how brain cells communicate. This discovery helps us understand how genes can affect how much we sleep.

Why Do We Sleep?

All living things, including humans, sleep a lot when they are very young. Dr. Sehgal and her team found out what keeps young fruit flies sleeping so much. They also found that if young flies don't get enough sleep, their mating behavior changes when they grow up. This suggests that sleep might be needed for the brain to develop properly for behaviors that help animals survive and have babies.

For adult animals, one idea is that sleep helps clear out waste from the body. Dr. Sehgal and her team found that sleep helps clean the brain by affecting the "blood brain barrier" in flies.

Body Clocks, Behavior, and the Blood Brain Barrier

The blood brain barrier (BBB) is like a shield that protects the brain from harmful molecules in the body. But it can also make it hard for medicines to reach the brain. Dr. Sehgal and her team found that the BBB in flies changes how "leaky" it is during the day and night. This means that a medicine for epilepsy worked better at a certain time of day. They have also mapped out the brain pathways that connect the body clock to how animals behave.

Sleep and Your Immune System

To find molecules that make us sleep, Dr. Toda and Dr. Sehgal's team looked at over 10,000 types of fruit flies. They found one molecule that causes sleep. They named this molecule "nemuri." It is a special protein that fights germs. When a fly gets an infection or doesn't get enough sleep, this molecule becomes active. It helps the fly survive by killing bacteria and making the fly sleep more.

Awards and Positions

Positions

• Director, Chronobiology and Sleep Institute (CSI), Perelman School of Medicine, University of Pennsylvania, 2019-present
• Director of Penn Chronobiology Program, 2014-2019
• Howard Hughes Medical Institute Investigator, 1997–Present
• John Herr Musser Professor of Neuroscience, Perelman School of Medicine, University of Pennsylvania
• Vice Chair of the Department of Neuroscience
• Co-Director of the Penn Medicine Neuroscience Center, 2008-2014

Awards

• Outstanding Scientific Achievement Award, Sleep Research Society
• Michael S. Brown Junior Faculty Research Award
• Stanley Cohen Senior Faculty Research Award
• Elected to the National Academy of Medicine (formerly Institute of Medicine), 2009
• Elected to the American Academy of Arts and Sciences, 2011
• Elected Fellow of the American Association for the Advancement of Science, 2016
• Elected to the National Academy of Sciences, 2016
• Switzer Prize from UCLA, 2020