Heritable oxidative phosphorylation differences in a pollutant resistant Fundulus heteroclitus population

Populations can adapt to stress including recent anthropogenic pollution. Our published data suggests heritable differences in hepatocyte oxidative phosphorylation (OxPhos) metabolism in field-caught killifish (Fundulus heteroclitus) from the highly polluted Elizabeth River, VA, USA, relative to fish from a nearby, relatively unpolluted reference site in King's Creek VA. Consistent with other studies showing that Elizabeth River killifish are resistant to some of the toxic effects of certain contaminants, OxPhos measurements in hepatocytes from field-caught King's Creek but not field-caught Elizabeth River killifish were altered by acute benzo [a] pyrene exposures. To more definitively test whether the enhanced OxPhos metabolism and toxicity resistance are heritable, we measured OxPhos metabolism in a laboratory-reared F3 generation from the Elizabeth River population versus a laboratory-reared F1 generation from the King's Creek population and compared these results to previous data from the field-caught fish. The F3 Elizabeth River fish compared to F1 King's Creek fish had significantly higher State 3 respiration (routine metabolism) and complex II activity, and significantly lower complex I activity. The consistently higher routine metabolism in the F3 and field-caught Elizabeth River fish versus F1 and field-caught King's Creek fish implies a heritable change in OxPhos function. The observation that LEAK, E-State, Complex I and Complex II were different in laboratory bred versus field-caught fish suggests that different physiological mechanisms produce the enhanced OxPhos differences. Finally, similar to field-caught Elizabeth River fish, acute benzo [a] pyrene exposure did not affect OxPhos function of the laboratory-reared F3 generation, supporting the heritability of the toxicity resistance. Overall, these results suggest that the Elizabeth River population has evolved genetic changes in physiological homeostasis that enhance routine metabolism, and we speculate that these genetic changes interact with environmental factors altering the physiological mechanisms (e.g., alter LEAK, Complex I, and electron transfer system capacity) used to achieve this enhanced metabolism.