Consequences of Lipid Restructuring During Temperature Variation on the Susceptibility of Biological Membranes to Lipid Peroxidation

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Life in the presence of oxygen involves the regular production of reactive oxygen species (including free radicals) and other highly reactive molecules. Some of these compounds can initiate lipid peroxidation (LPO), a series of reactions that can significantly alter the chemical, physical, and functional properties of biological membranes. Although LPO may damage cells, a certain level appears necessary for a variety of cellular processes. Poikilothermic animals (i.e., animals that live at a variety of body temperatures) represent the vast majority of animals that live on earth. In order to keep membranes at or near an optimal fluidity, poikilotherms alter the chemical compositions of their biological membranes with changes in body temperature. At low temperatures, poikilotherms have membranes particularly rich in the phospholipid phosphatidylethanolamine and omega-3 polyunsaturated fatty acids. In addition, their cells often have higher contents of energy-producing mitochondria, the primary source of reaction oxygen species. These changes could make animals at cold temperatures more vulnerable to LPO than their warm-bodied counterparts. At the same time, low temperature slows rates of LPO and production of reactive oxygen species. Using a fish model (the striped bass, Morone saxatilis), this work will test the central hypothesis that membrane susceptibility to LPO is maintained over a range of body temperatures. Other objectives include quantification of LPO products and antioxidant defenses. Recently developed fluorescent probes and chromatographic techniques will be used to address hypotheses. LPO is intensively studied in biomedicine and aging biology, yet the significance of membrane peroxidation, within the contexts of temperature physiology, has yet to be elucidated. Studies aimed at determining susceptibilities to LPO are necessary to clarify how poikilotherms avoid potentially damaging peroxidation of biological membranes. This research will contribute to a mechanistic understanding of biochemical factors that make life possible over a range of temperatures. The project will incorporate mentorship and training of graduate, undergraduate, and high school students (including research at a marine laboratory), collaboration with a faculty member from a predominantly undergraduate institution, consultation with an established researcher in the field of biomedical research, and outreach designed to educate children about how organisms adapt to life at different temperatures.