Zephanie Lung, M.Sc. Biology 2019

Regulation of DNA damage repair in response to freezing and anoxia in the wood frog, Rana sylvatica


The wood frog, Rana sylvatica, can survive freezing up to 65% of its body water in subzero temperatures and endures anoxia due to the cessation of vital functions while frozen. Fluctuating oxygen levels, particularly upon reperfusion and reoxygenation, increase vulnerability to reactive oxygen species and oxidative damage to macromolecules, including DNA. This thesis assesses DNA damage and responses by antioxidant capacity and DNA damage repair pathways to freezing or anoxia in wood frog liver and skeletal muscle. DNA oxidation remained largely constant, with observed increased antioxidant capacity in anoxia but not freezing. Although many observed DNA repair proteins displayed constant expression through stress and recovery, the MRN complex, Ku heterodimer, and ligation complexes, displayed changes in expression that vary based on tissue and stress. Overall, the data indicate that DNA damage is minimized through tissue and stress specific regulation of antioxidant capacity and DNA damage repair to preserve genomic integrity.