Cancer Foundation Blog

...continued from Monday:
Long-term survival without oxygen (anoxic) is most highly developed in two vertebrate groups – some freshwater turtles and selected fish species. Both Red-eared Sliders (Trachemys scripta elegans) and Painted Turtles (Chrysemys picta) have become established models for anoxia tolerance research. As a result of biochemical adaptations these turtles are capable of hibernating in oxygen-free cold water (<10°C). Although humans cannot live without oxygen for more than a few minutes, these turtles can survive with no oxygen for weeks or months! My PhD research focuses primarily on the mechanisms of cell cycle arrest during anoxia exposure in the freshwater turtle (Trachemys scripta elegans).
To understand the biochemical mechanisms that allow organisms to live without oxygen, researchers must look at the molecular adaptations occurring in the animal under stress. Studies conducted in Dr. Kenneth B. Storey’s lab have indentified prominent groups of expressed genes during anoxia. Many of these studies indicate changes to several aspects of cell cycle regulation, providing an indication that the cell cycle may function as a key component in anoxia survival. Mutated genes are predominately found in all cancers, many of which are key players in the cell cycle and cause resistance to chemotherapy. We recently found that the activities of many of these genes are tightly regulated during anoxia in the turtle. We are currently determining how these genes are expressed and controlled in order to regulate proliferation in response to low oxygen environments.
Clearly, the turtle provides an excellent model animal for studying the process of cell cycle arrest, and the current research provides many new questions regarding the impact of cell cycle arrest on hypoxic tumor growth. Discovering the commonalities of response pathways in organisms as diverse as worms, flies, and turtles will undoubtedly lead to refined treatment of both ischemic injuries and hypoxic tumor cores that are often resistant to radiation and chemotherapy.