Almost all organisms on Earth share the basic metabolic pathways that support anaerobic metabolism, and yet many organisms, including most vertebrates, cannot survive for long without molecular oxygen. Embryos of the annual killifish Austrofundulus limnaeus are an excellent model for investigating the mechanistic basis of anoxia-tolerance and anoxia-sensitivity in vertebrates. Embryos of A. limnaeus undergo a unique period of developmental dormancy called diapause. Recent evidence suggests that embryos of A. limnaeus have some very unique physiological adaptations that are associated with tolerance of long-term anoxia. Both dormant and actively developing embryos of A. limnaeus can survive for months without oxygen at 250C. Embryos of A. limnaeus display a massive depletion of ATP during the initial hours of anoxic exposure and lose their mitochondrial membrane potential during this same time frame. These two events are typically associated with cell death in other vertebrate cells, but embryos of A. limnaeus quickly recover from these drastic changes in mitochondrial physiology and energetics. These observations imply that cells of A. limnaeus embryos have some extraordinary characteristics compared to other vertebrates, and even to other vertebrates that exhibit substantial tolerance of anoxia. I will identify the metabolic pathways that support anoxia tolerance in isolated cells of A. limnaeus, assess mitochondrial function and energetics during anoxia and recovery from anoxia, and test the hypothesis that an alternate metabolic pathways supported by the enzyme phosphoenolpyruvate carboxykinase is critical for the survival of anoxia. By using the integrative approaches outlined in the proposal we can hopefully create a more complete picture of the cellular physiology of anoxia-tolerance in the cells if this exceptional vertebrate extremophile.

Public Health Relevance

Heart disease and stroke are responsible for the vast majority of deaths in the developed world. The extreme sensitivity of human heart and brain tissue to lack of oxygen is poorly understood at the cellular level. By understanding the cellular mechanisms that support extreme anoxia tolerance in embryos of the annual killifish, Austrofundulus limnaeus, we may be able to develop treatments to mediate or prevent the damaging effects of heart attacks and strokes to humans.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL095454-02
Application #
8018129
Study Section
Special Emphasis Panel (ZRG1-CVS-B (50))
Program Officer
Wong, Renee P
Project Start
2010-01-15
Project End
2013-12-31
Budget Start
2011-01-01
Budget End
2011-12-31
Support Year
2
Fiscal Year
2011
Total Cost
$365,000
Indirect Cost
Name
Portland State University
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
052226800
City
Portland
State
OR
Country
United States
Zip Code
97207
Hand, Steven C; Denlinger, David L; Podrabsky, Jason E et al. (2016) Mechanisms of animal diapause: recent developments from nematodes, crustaceans, insects, and fish. Am J Physiol Regul Integr Comp Physiol 310:R1193-211
Podrabsky, Jason E; Hand, Steven C (2015) Physiological strategies during animal diapause: lessons from brine shrimp and annual killifish. J Exp Biol 218:1897-906
Wagner, Josiah T; Podrabsky, Jason E (2015) Extreme tolerance and developmental buffering of UV-C induced DNA damage in embryos of the annual killifish Austrofundulus limnaeus. J Exp Zool A Ecol Genet Physiol 323:10-30
Meller, Camie L; Meller, Robert; Simons, Roger P et al. (2014) Patterns of ubiquitylation and SUMOylation associated with exposure to anoxia in embryos of the annual killifish Austrofundulus limnaeus. J Comp Physiol B 184:235-47
Anderson, Skye N; Podrabsky, Jason E (2014) The effects of hypoxia and temperature on metabolic aspects of embryonic development in the annual killifish Austrofundulus limnaeus. J Comp Physiol B 184:355-70
Meller, Camie L; Podrabsky, Jason E (2013) Avoidance of apoptosis in embryonic cells of the annual killifish Austrofundulus limnaeus exposed to anoxia. PLoS One 8:e75837
Meller, Camie L; Meller, Robert; Simon, Roger P et al. (2012) Cell cycle arrest associated with anoxia-induced quiescence, anoxic preconditioning, and embryonic diapause in embryos of the annual killifish Austrofundulus limnaeus. J Comp Physiol B 182:909-20
Podrabsky, Jason E; Culpepper, Kristin M (2012) Cell cycle regulation during development and dormancy in embryos of the annual killifish Austrofundulus limnaeus. Cell Cycle 11:1697-704
Podrabsky, Jason E; Menze, Michael A; Hand, Steven C (2012) Long-Term survival of anoxia despite rapid ATP decline in embryos of the annual killifish Austrofundulus limnaeus. J Exp Zool A Ecol Genet Physiol 317:524-32
Carey, Hannah V; Martin, Sandra L; Horwitz, Barbara A et al. (2012) Elucidating nature's solutions to heart, lung, and blood diseases and sleep disorders. Circ Res 110:915-21