Jason R Treberg

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Respiratory complex II oxidizes succinate to fumarate as part of the Krebs cycle and reduces ubiquinone in the electron transport chain. Previous experimental evidence suggested that complex II is not a significant contributor to the production of reactive oxygen species (ROS) in isolated mitochondria or intact cells unless mutated. However, we find that(More)
Mitochondrial proton and electron leak have a major impact on mitochondrial coupling efficiency and production of reactive oxygen species. In the first part of this chapter, we address the molecular nature of the basal and inducible proton leak pathways, and their physiological importance. The basal leak is unregulated, and a major proportion can be(More)
We compared levels of the major organic osmolytes in the muscle of elasmobranchs, including the methylamines trimethylamine oxide (TMAO), betaine and sarcosine as well as the beta-amino acids taurine and beta-alanine, and the activities of enzymes of methylamine synthesis (betaine and TMAO) in species with a wide range of urea contents. Four marine, a(More)
Winter skates, Leucoraja ocellata, exposed to 80% and 50% seawater (SW) exhibited rapid and significant weight gains followed by a slight recovery to new steady state levels within 8 days. Skates were acclimated at each salinity (100% SW [N = 16], 80% SW [N = 8], 50% SW [N = 8]), anesthetized (MS222) and bled from the caudal vein. In 100% SW, skate plasma(More)
Individual sites of superoxide production in the mitochondrial respiratory chain have previously been defined and partially characterized using specific inhibitors, but the native contribution of each site to total superoxide production in the absence of inhibitors is unknown. We estimated rates of superoxide production (measured as H(2)O(2)) at various(More)
The hyperinsulism/hyperammonemia (HI/HA) syndrome is caused by glutamate dehydrogenase (GDH) gain-of-function mutations that reduce the inhibition by GTP, consequently increasing the activity of GDH in vivo. The source of the hyperammonemia in the HI/HA syndrome remains unclear. We examined the effect of systemic activation of GDH on ammonia metabolism in(More)
Smelt (Osmerus mordax) were maintained at either ambient water temperature or approximately 5 degrees C and various aspects of their freeze-avoidance response were examined from early winter until early spring. Plasma levels of glycerol, trimethylamine oxide (TMAO) and urea were elevated by December 15 and continued to increase in fish held in ambient(More)
The production of H(2)O(2) by isolated mitochondria is frequently used as a measure of mitochondrial superoxide formation. Matrix superoxide dismutase quantitatively converts matrix superoxide to H(2)O(2). However, matrix enzymes such as the glutathione peroxidases can consume H(2)O(2) and compete with efflux of H(2)O(2), causing an underestimation of(More)
The unusual energy metabolism of elasmobranchs is characterized by limited or absent fatty acid oxidation in cardiac and skeletal muscle and a great reliance on ketone bodies and amino acids as oxidative fuels in these tissues. Other extrahepatic tissues in elasmobranchs rely on ketone bodies and amino acids for aerobic energy production but, unlike muscle,(More)