Mitochondrial Respiration In Skeletal Muscle Mitochondria From Desert Pupfish Suggests Limitation Of Metabolic Substrates As A Mechanism For Paradoxical Anaerobism

Abstract

Skeletal muscle mitochondria were isolated from desert pupfish (Cyprinodon spp) that were acclimated to ecologically relevant temperatures of 28 °C (M28) and 33 °C (M33). The respiratory control ratio (RCR) of M33 pupfish was ~2.6X lower than that of M28 pupfish, initially suggesting mitochondria were damaged by the warmer temperature. However, state 4 respiration was below expected values in both M28 and M33 pupfish suggesting little proton leak. Further, membrane potential was lower in the M33 pupfish than M28 pupfish and did not change with assay temperature. These data suggested a reduced proton motive force in M33 pupfish. Analyses of respiration as a function of membrane potential suggest a block in substrate utilization in M33 pupfish. M33 pupfish also experience reduced production of reactive oxygen species (ROS) from the Q site of complex I. Taken all together, the data suggest pupfish may be limiting mitochondrial use to avoid ROS production by restricting access of substrates to the mitochondrion. These results are consistent with our measurements of oxygen consumption in intact fish. Specifically, fish acclimated to 33 °C demonstrate extended periods of paradoxical anaerobism in which oxygen consumption is absent despite the presence of oxygen.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.