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Inter-relationship between mitochondrial function and susceptibility to oxidative stress in red- and white-blooded Antarctic notothenioid fishes

TitleInter-relationship between mitochondrial function and susceptibility to oxidative stress in red- and white-blooded Antarctic notothenioid fishes
Publication TypeJournal Article
Year of Publication2011
AuthorsMueller, IA, Grim, JM, Beers, JM, Crockett, EL, O’Brien, KM
JournalJournal of Experimental Biology
Volume214
Pagination3732–3741
Abstract

It is unknown whether Antarctic fishes can defend themselves against oxidative stress induced by elevations in temperature. Wehypothesized that Antarctic icefishes, lacking the oxygen-binding protein hemoglobin, might be more vulnerable to temperatureinducedoxidative stress compared with red-blooded notothenioids because of differences in their mitochondrial properties.Mitochondria from icefishes have higher densities of phospholipids per mg of mitochondrial protein compared with red-bloodedspecies, and these phospholipids are rich in polyunsaturated fatty acids (PUFA), which can promote the formation of reactiveoxygen species (ROS). Additionally, previous studies have shown that multiple tissues in icefishes have lower levels ofantioxidants compared with red-blooded species. We quantified several properties of mitochondria, including proton leak, rates ofROS production, membrane composition and susceptibility to lipid peroxidation (LPO), the activity of superoxide dismutase (SOD)and total antioxidant power (TAOP) in mitochondria isolated from hearts of icefishes and red-blooded notothenioids. Mitochondriafrom icefishes were more tightly coupled than those of red-blooded fishes at both 2°C and 10°C, which increased the production ofROS when the electron transport chain was disrupted. The activity of SOD and TAOP per mg of mitochondrial protein wasequivalent between icefishes and red-blooded species, but TAOP normalized to mitochondrial phospholipid content wassignificantly lower in icefishes compared with red-blooded fishes. Additionally, membrane susceptibility to peroxidation was onlydetectable in icefishes at 1°C and not in red-blooded species. Together, our results suggest that the high density of mitochondrialphospholipids in hearts of icefishes may make them particularly vulnerable to oxidative stress as temperatures rise.

DOI10.1242/jeb.062042
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