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Satchidananda Panda

 

Satchidananda Panda

Satchidananda Panda

Associate Professor
Regulatory Biology Laboratory

"Going to bed at night and waking up in the morning is a seemingly simple routine we follow in every season. I want to understand how our brain clock keeps track of time in all seasons and time zones and tells our body when to sleep, when to wake up, and when to eat."

In mammals, the circadian timing system is composed of a central circadian clock in the brain and subsidiary oscillators in most peripheral tissues. The master clock in the brain is set by light and determines the overall diurnal or nocturnal preference of an animal, including sleep-wake cycles and feeding behavior. The clocks in peripheral organs, however, are largely insensitive to changes in the light regime. Instead, their phase and amplitude are affected by many factors, including feeding time.

All clocks keep time through the fall and rise of gene activity on a roughly 24-hour schedule that anticipates environmental changes and adapts many of the body's physiological functions to the appropriate time of day. In particular, the oscillator in the liver–the body's metabolic clearinghouse–helps the organism adapt to a daily pattern of food availability by temporally tuning the activity of thousands of genes regulating metabolism and physiology.

To investigate whether the circadian rhythms in hepatic transcription were solely controlled by the liver's clock in anticipation of food or responded to actual food intake, Panda and his team put normal mice and mice without functional clocks on strictly controlled feeding and fasting schedules. Their experiments revealed that the daily waxing and waning of thousands of genes in the liver is mostly controlled by food intake and not, as conventional wisdom had it, by the body's circadian clock. For example, the activity of genes that encode enzymes needed to break down sugars rose immediately after a meal, while the activity of genes encoding enzymes needed to break down fat was highest after a prolonged fast. Consequently, a clearly defined daily feeding schedule puts the enzymes of metabolism in shift work and optimizes burning of sugar and fat.

Their findings could explain why shift workers are unusually prone to metabolic syndrome, diabetes, high cholesterol levels, and obesity. It is not the shift work per se that wreaks havoc on the body's metabolism but changing shifts and weekends, when workers switch back to a regular day-night cycle.

Lab Photo

Left to right:
Ruth Fischer, Hiep Le, Chrissta Maracle, Satchin Panda, Luciano DiTacchio, Christopher Vollmers, Megumi Hirota, Sheena Keding

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Satchidananda Panda

Faculty

Satchidananda Panda

Satchidananda Panda

Associate Professor
Regulatory Biology Laboratory

Satchin Panda, an associate professor in the Regulatory Biology Laboratory, is interested in understanding the molecular mechanism of the biological clock in a mouse model system. The biological clock or circadian oscillator in most organisms coordinates behavior and physiology with the natural light-dark cycle. His laboratory uses genetic, genomics and biochemical approaches to identify genes under circadian regulation in different organs and to understand the mechanism of such regulation. His lab also tries to characterize the mechanism by which the circadian oscillator is synchronized to the natural light-dark condition. Both classical rod/cone photoreceptors and a newly identified ocular photopigment melanopsin participate in photoentrainment of the clock. Research in his lab is geared towards identifying molecular components and events critical for transmitting light information from the eye to the master oscillator in the brain.

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