Colloquium on the Brain and Cognition with Elena Gracheva, PhD, Yale University
Thursday, April 27 at 4:00pm
Singleton Auditorium (46-3002)
Cellular, Molecular, and Physiological Adaptations of Hibernation
Mammalian hibernation is fascinating. During a short period of time, hibernating animals undergo dramatic adaptive changes, including a reduction in heart and respiration rate and a decrease in core body temperature from 37°C (98.6°F) to 4°C (39°F), yet they do not experience cold-induced pain, and their organs continue to function despite being cold and deprived of oxygen for 8 month out of the year! Moreover, since these animals do not eat or drink during hibernation, they must rely solely on the management and utilization of their internal resources for long-term survival. How hibernators achieve such a remarkable physiological adaptation, remains unknown.
We use hibernating 13-lined Ground squirrels (an obligatory hibernator) and Syrian hamsters (a non-obligatory hibernator), to tackle fundamental biological questions from perspectives unachievable using the standard animal models alone. Specifically, we are interested in studying molecular evolution of mammalian hibernation and cellular adaptations that these animals evolve in order to survive prolonged periods of hypothermia, water deprivation and starvation. We are also trying to pinpoint the molecular and physiological basis of hibernation induction. Comparative analysis of three rodent species—such as ground squirrels, hamsters and mice (non-hibernator)—at the behavioral, cellular and molecular levels, will help us to delineate the multitude of adaptations that hibernators evolved in order to survive harsh environment and as a result came to inhabit a wide geographical range.
I am a biochemist, cell biologist and neurophysiologist by training with 20 years of experience in biomedical research. The main goal of my lab is to understand the cellular, molecular and physiological basis of mammalian hibernation. We are using non–standard animal models such as hibernating thirteen–lined ground squirrels and Syrian hamsters to delineate different aspects of temperature sensitivity, thermoregulation, fluid/ionic balance, hunger/satiety control and seasonal reproduction. We employ multidisciplinary approach, including electrophysiology, molecular biology, imaging, behavioral paradigms, genomics, transcriptomics and bioinformatics. My notable contributions to science include the discovery of the infrared receptors in snakes and bats, and the identification of structural elements responsible for these properties, and elucidation of the mechanisms responsible for cold tolerance and fluid ionic balance control in mammalian hibernators. Our recent work shed light on how ground squirrels can survive without water on cold for up to 8 months without tissue damage and deterioration.