The effect of temperature on protein metabolism in fish: the possible consequences for wild Atlantic salmon (Salmo salar L.) stocks in Europe as a result of global warming

Summary

Introduction

In fish, it is generally accepted that increased temperatures, within the thermal range for a particular species, will lead to increased growth rates providing that food is not limiting. Protein growth occurs when protein synthesis exceeds protein degradation. Therefore, understanding the effect of temperature on protein synthesis and food/protein consumption is fundamental to predicting the potential effects of climatic change on the growth performance of fish. Within the preferred thermal range, long-term exposure of ectotherms to lower or higher environmental temperatures may lead to a degree of physiological and biochemical independence from the acute effects of the alteration in environmental temperature, a process generally termed temperature compensation. The limits within which such independence (or compensation) may fall are ultimately determined by the genetic potential (genotype) of an organism. Since gene expression is dependent upon the synthesis of proteins, it seems likely that metabolic adjustments may be accompanied by changes in protein synthesis. In vivo rates of protein synthesis have most commonly been studied by measuring radiolabelled amino acid incorporation rates using the ‘flooding dose’ technique (Garlick, McNurlan & Preedy, 1980). This technique, and its experimental application in fish biology, have been covered in depth in recent reviews (Houlihan, Carter & McCarthy, 1995a, b; Houlihan et al., 1995c) and will not be considered here.