Amita Sehgal

Amita Sehgal is a molecular biologist and chronobiologist in the Department of Neuroscience at the Perelman School of Medicine at the University of Pennsylvania. Sehgal has been involved in the discovery of Drosophila TIM and many other important components of the Drosophila clock mechanism. Sehgal has contributed greatly to the development of Drosophila as a model for the study of sleep. Her research continues to be focused on understanding the genetic basis of sleep and also how circadian systems relate to other aspects of physiology.

Dr. Sehgal grew up in India, and earned her BSc as an undergraduate at Delhi University and her MSc at Jawaharlal Nehru University, both in New Delhi, India. After earning her master's degree, she worked in a lab studying the DNA repair process in Muscular Dystrophy. She began pursuing her PhD in cell biology and genetics at Cornell University in 1983. It was here, while studying a human neuronal growth factor, that her interest in science truly developed. In 1988, she began her Postdoctoral Fellowship at Rockefeller University in the lab of Michael Young, where she had her first exposure to the study of circadian rhythms, a field in which she has since remained.

Amita Sehgal has contributed tremendously towards the understanding of the biological clock of Drosophila melanogaster In 1994, Sehgal, Price, Man, and Young, through forward genetics, discovered a mutant of the gene timeless (TIM) in Drosophila melanogaster. In the following year, Sehgal et al. cloned TIM through positional cloning and were able to show that TIM and PER had similar cycling levels of their mRNA and protein. A yeast 2-hybrid then showed that TIM protein binds directly to PER. PER and TIM dimerize and accumulate during the day. In the evening, they enter the nucleus to inhibit the transcription of their mRNA. Phosphorylation of PER and TIM then leads to their degradation. In 1996, Sehgal was involved in an experiment that showed degradation in TIM levels caused by a pulse of light that resets the molecular clock. Sehgal and her team later showed is responsible for the degradation of TIM.

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