Life in the freezer: protein metabolism in Antarctic fish.

Keiron P P Fraser,Simeon L Hill,Andrew Clarke,Lloyd S Peck,Melody S Clark

doi:10.1098/rsos.211272

Abstract

Whole-animal, in vivo protein metabolism rates have been reported in temperate and tropical, but not Antarctic fish. Growth in Antarctic species is generally slower than lower latitude species. Protein metabolism data for Antarctic invertebrates show low rates of protein synthesis and unusually high rates of protein degradation. Additionally, in Antarctic fish, increasing evidence suggests a lower frequency of successful folding of nascent proteins and reduced protein stability. This study reports the first whole-animal protein metabolism data for an Antarctic fish. Groups of Antarctic, Harpagifer antarcticus, and temperate, Lipophrys pholis, fish were acclimatized to a range of overlapping water temperatures and food consumption, whole-animal growth and protein metabolism measured. The rates of protein synthesis and growth in Antarctic, but not temperate fish, were relatively insensitive to temperature and were significantly lower in H. antarcticus at 3°C than in L. pholis. Protein degradation was independent of temperature in H. antarcticus and not significantly different to L. pholis at 3°C, while protein synthesis retention efficiency was significantly higher in L. pholis than H. antarcticus at 3°C. These results suggest Antarctic fish degrade a significantly larger proportion of synthesized protein than temperate fish, with fundamental energetic implications for growth at low temperatures.

Highlights

Resting or standard metabolic rates of Antarctic ectotherms are generally considered low [3,4], and growth rates reduced [5–8] in comparison to temperate and tropical species
Recent research has suggested that reduced growth rates in Antarctic organisms may be driven by reduced rates of protein synthesis and/or protein retention [4,9,10]
There were no significant differences in fish masses between temperature groups or species; data were not mass standardized prior to analysis

Summary

Introduction

The Southern Ocean is characterized by low, stable temperatures and strong seasonal variation in sea ice, light and primary productivity [1,2]. Resting or standard metabolic rates of Antarctic ectotherms are generally considered low [3,4], and growth rates reduced [5–8] in comparison to temperate and tropical species. Recent research has suggested that reduced growth rates in Antarctic organisms may be driven by reduced rates of protein synthesis and/or protein retention [4,9,10].

Objectives

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Conclusion