BAKER, P.J.*; COSTANZO , J.P.; LEE, R.E.; Miami University; Miami University; Miami University: Induction of Oxidative Stress in a Terrestrially-Hibernating Turtle

Hatchlings of the painted turtle, Chrysemys picta, hibernate terrestrially and may survive subfreezing temperatures by supercooling or by tolerating the freezing of their tissues. Previous research on this species has focused on the physiological challenges encountered during these stresses. Whether supercooled or frozen, an ischemic hypoxia develops because tissue perfusion is limited by freezing and/or low temperature. Resumption of aerobic respiration following hypoxia has the potential for inducing oxidative stress if hatchlings do not have a well-developed system to minimize or prevent damage by reactive oxygen species (ROS). We examined thiobarbituric acid reactive substances (TBARs), an indicator of lipid peroxidation, in hatchling C. picta following survivable, 48-h bouts of supercooling (-5�C), freezing (-2.5�C), or hypoxia (15�C). We collected plasma, brain, and liver samples after a 24-h period of recovery (4�C) and analyzed these tissues for oxidative damage. We found a significant increase in TBARs in the plasma, but not in the brain or liver, of frozen/thawed hatchlings as compared to untreated controls. TBARs did not increase significantly in supercooled or hypoxia-exposed hatchlings. Although preliminary, our results suggest that cold-acclimated hatchling C. picta have a well-developed antioxidant defense system that minimizes damage due to oxidative stress. However, freezing/thawing may cause greater oxidative damage than hypoxia or supercooling. NSF IOB 0416750