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Mitochondrial biogenesis in cold-bodied fishes

TitleMitochondrial biogenesis in cold-bodied fishes
Publication TypeJournal Article
Year of Publication2011
AuthorsO’Brien, KM
JournalJournal of Experimental Biology

Mitochondrial biogenesis is induced in response to cold temperature in many organisms. The effect is particularly pronounced inectotherms such as fishes, where acclimation to cold temperature increases mitochondrial density. Some polar fishes also haveexceptionally high densities of mitochondria. The net effect of increasing mitochondrial density is threefold. First, it increases theconcentration of aerobic metabolic enzymes per gram of tissue, maintaining ATP production. Second, it elevates the density ofmitochondrial membrane phospholipids, enhancing rates of intracellular oxygen diffusion. Third, it reduces the diffusion distancefor oxygen and metabolites between capillaries and mitochondria. Although cold-induced mitochondrial biogenesis has been welldocumented in fishes, little is known about the molecular pathway governing it. In mammals, the co-transcriptional activatorperoxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1 ) is thought to coordinate the three components ofmitochondrial biogenesis: the synthesis of mitochondrial proteins, the synthesis of phospholipids and the replication ofmitochondrial DNA. Some components of the mitochondrial biogenic pathway are conserved between fishes and mammals, yetthe pathway appears more versatile in fishes. In some tissues of cold-acclimated fishes, the synthesis of mitochondrial proteinsincreases in the absence of an increase in phospholipids, whereas in some polar fishes, densities of mitochondrial phospholipidsincrease in the absence of an increase in proteins. The ability of cold-bodied fishes to fine-tune the mitochondrial biogenicpathway may allow them to modify mitochondrial characteristics to meet the specific needs of the cell, whether it is to increaseATP production or enhance oxygen diffusion.

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