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Biology Colloquium | Nisha N Kannan

September 14 @ 1:30 pm - 2:30 pm

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Event Details

Guest Session_NishaNKannan


Title: Caffeine disrupts the circadian rhythm in Drosophila
Abstract: The circadian clock governs the timing of sleep-wake cycles as well as of other behavioral, physiological and metabolic processes. While the circadian clock mediates the timing of sleep, homeostatic mechanisms modulate the amount and depth of sleep. Although evidence from previous studies showed that caffeine suppresses sleep, it is important to understand whether caffeine influences the endogenous time-keeping system. We examined the effect of caffeine on the circadian clock and the behavioral rhythmicity in Drosophila. The results of our study showed that acute caffeine treatment reduced the amount of sleep through the homeostatic pathway. On the other hand, chronic caffeine treatment delayed the timing of sleep onset indicating that chronic caffeine treatment may affect the endogenous circadian clock. Furthermore, with increasing concentrations of caffeine flies exhibited a longer free-running periodicity or arrhythmicity under constant darkness. The results of our study showed that acute caffeine treatment suppresses sleep through the homeostatic pathway whereas prolonged administration of caffeine disrupts the transcriptional rhythm of core clock genes such as period, timeless and drives behavioral arrhythmicity in flies. I will also talk about the role of circadian clock in triglyceride metabolism of Drosophila. Although evidence from various studies indicate the importance of circadian timing system in regulating the metabolism, the specific role of clock genes in metabolic function remains to be understood. We assessed the differential role of circadian photoreceptor cryptochrome (cry) expressing central pacemaker neurons and the fat body peripheral circadian clock in triglyceride metabolism. The flies with cry down regulated in the fat bodies showed a decrease in triglyceride levels whereas flies lacking cry in the central clock neurons showed an increase in the triglyceride level compared to the control flies. These results suggest that the circadian photoreceptor cry expressing central clock neurons and fat body peripheral clock oppose each other in the regulation of triglyceride metabolic function in Drosophila.

Meeting ID: 999 8176 0548 Passcode: p9xv9kuI
Speaker’s Bio: Dr. Kannan is presently an Assistant Professor in the Indian Institute of Science Education and Research, Thiruvananthapuram.
After completing her Ph.D. in chronobiology from Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, she moved to Okayama University, Japan  as a Post-Doctoral fellow
Research in her laboratory is broadly focused to understand the circadian clock at the genetic and neuronal network level and how it rhythmically regulates the behavior, physiology, and metabolism of an organism. They use the model organism fruit fly Drosophila that offers convenient tools for conducting comprehensive genetic, molecular, and behavioral studies.
She is the DBT/Wellcome Trust India Alliance Early Career fellow 2017-2021



September 14
1:30 pm - 2:30 pm


Department of Biology


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