Meeting Abstract
29.3 Wednesday, Jan. 5 Oxidative stress occurs in cardiac muscle of some Antarctic icefishes in response to an increase in temperature MUELLER, I.A.*; O’BRIEN, K.M.; University of Alaska, Fairbanks; University of Alaska, Fairbanks iamueller@alaska.edu
Loss of hemoglobin (Hb) in Antarctic icefishes (family Channichthyidae, suborder Notothenioidei) is correlated with an increase in mitochondrial density, and changes in mitochondrial structure and properties. Our previous work has shown that proton leak is lower in mitochondria isolated from heart ventricles of icefish compared to red-blooded notothenioids, resulting in higher rates of production of reactive oxygen species when the electron transport chain is disrupted. We sought to determine whether differences in mitochondrial characteristics might increase oxidative stress in icefishes exposed to elevations in temperature, and contribute to their lower thermal tolerance compared to red-blooded notothenioids. Levels of oxidized proteins were quantified in heart ventricle and oxidative pectoral adductor muscle of Chaenocephalus aceratus (-Hb), Chionodraco rastrospinosus (-Hb), Notothenia coriiceps (+Hb) and Gobionotothen gibberifrons (+Hb) held at 0 °C and exposed to their critical thermal maximum (CTmax). Transcript levels of the antioxidants superoxide dismutase and catalase were also quantified in heart ventricles. Levels of oxidized proteins increased from 0.34±0.33 to 9.33±1.56 mmol carbonyl mol-1 protein in hearts of C. aceratus exposed to their CTmax, but did not change in hearts of any other species or in pectoral muscle of any species. Despite an increase in levels of oxidized proteins in hearts of C. aceratus, transcript levels of antioxidants did not change, and increased only in hearts of red-blooded fishes in response to exposure to CTmax. Together, these data suggest elevations in temperature increase oxidative damage in cardiac muscle of some icefishes, which may contribute to their lower thermal tolerance. Supported by a grant from NSF (ANT-074130).
