Cardiac mitochondrial metabolism may contribute to differences in thermal tolerance of red- and white-blooded Antarctic notothenioid fishes

Studies in temperate fishes provide evidence that cardiac mitochondrial function and the capacity to fuel cardiac work contribute to thermal tolerance. Here, we tested the hypothesis that decreased cardiac aerobic metabolic capacity contributes to the lower thermal tolerance of the haemoglobinless A...

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Bibliographic Details
Published in:Journal of Experimental Biology
Main Authors: O'Brien, Kristin M., Rix, Anna S., Egginton, Stuart, Farrell, Anthony P., Crockett, Elizabeth L., Schlauch, Karen, Woolsey, Rebekah, Hoffman, Megan, Merriman, Sean
Format: Text
Language:English
Published: The Company of Biologists Ltd 2018
Subjects:
RESEARCH ARTICLE
Antarctic
Antarc*
Icefish
Online Access:http://jeb.biologists.org/cgi/content/short/221/15/jeb177816
https://doi.org/10.1242/jeb.177816
Description
Summary:Studies in temperate fishes provide evidence that cardiac mitochondrial function and the capacity to fuel cardiac work contribute to thermal tolerance. Here, we tested the hypothesis that decreased cardiac aerobic metabolic capacity contributes to the lower thermal tolerance of the haemoglobinless Antarctic icefish, Chaenocephalus aceratus , compared with that of the red-blooded Antarctic species, Notothenia coriiceps. Maximal activities of citrate synthase (CS) and lactate dehydrogenase (LDH), respiration rates of isolated mitochondria, adenylate levels and changes in mitochondrial protein expression were quantified from hearts of animals held at ambient temperature or exposed to their critical thermal maximum (CT max ). Compared with C. aceratus , activity of CS, ATP concentration and energy charge were higher in hearts of N. coriiceps at ambient temperature and CT max . While state 3 mitochondrial respiration rates were not impaired by exposure to CT max in either species, state 4 rates, indicative of proton leakage, increased following exposure to CT max in C. aceratus but not N. coriiceps . The interactive effect of temperature and species resulted in an increase in antioxidants and aerobic metabolic enzymes in N. coriiceps but not in C. aceratus . Together, our results support the hypothesis that the lower aerobic metabolic capacity of C. aceratus hearts contributes to its low thermal tolerance.

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