Individuals Maintain Similar Rates of Protein Synthesis over Time on the Same Plane of Nutrition under Controlled Environmental Conditions.

Ian D Mccarthy,Peter W Watt,Stewart F Owen,Dominic F Houlihan

doi:10.1371/journal.pone.0152239

Abstract

Consistent individual differences in animal performance drive individual fitness under variable environmental conditions and provide the framework through which natural selection can operate. Underlying this concept is the assumption that individuals will display consistent levels of performance in fitness-related traits and interest has focused on individual variation and broad sense repeatability in a range of behavioural and physiological traits. Despite playing a central role in maintenance and growth, and with considerable inter-individual variation documented, broad sense repeatability in rates of protein synthesis has not been assessed. In this study we show for the first time that juvenile flounder Platichthys flesus reared under controlled environmental conditions on the same plane of nutrition for 46 days maintain consistent whole-animal absolute rates of protein synthesis (As). By feeding meals containing 15N-labelled protein and using a stochastic end-point model, two non-terminal measures of protein synthesis were made 32 days apart (d14 and d46). As values (mass-corrected to a standard mass of 12 g) showed 2- to 3-fold variation between individuals on d14 and d46 but individuals showed similar As values on both days with a broad sense repeatability estimate of 0.684 indicating significant consistency in physiological performance under controlled experimental conditions. The use of non-terminal methodologies in studies of animal ecophysiology to make repeat measures of physiological performance enables known individuals to be tracked across changing conditions. Adopting this approach, repeat measures of protein synthesis under controlled conditions will allow individual ontogenetic changes in protein metabolism to be assessed to better understand the ageing process and to determine individual physiological adaptive capacity, and associated energetic costs of adaptation, to global environmental change.

Highlights

IntroductionConsistent individual differences (CID) [1] in physiology and behaviour drive individual fitness (i.e. survival and reproductive output) under variable environmental conditions and provide the framework through which natural selection can operate [2, 3, 4]
Consistent individual differences (CID) [1] in physiology and behaviour drive individual fitness under variable environmental conditions and provide the framework through which natural selection can operate [2, 3, 4]
The wide application of the flooding dose technique using 3Hphenylalanine across a range of non-human taxa enables direct comparison of data between studies within and across taxa [26, 28, 29], the drawback of this technique is that it provides a single terminal measure of protein synthesis precluding any studies of broad sense repeatability and so conclusions drawn on inter-individual differences in physiological performance are based on a single measure

Summary

Introduction

Consistent individual differences (CID) [1] in physiology and behaviour drive individual fitness (i.e. survival and reproductive output) under variable environmental conditions and provide the framework through which natural selection can operate [2, 3, 4]. Most studies of protein synthesis in non-mammalian animals have made single terminal measures using radiolabelled (3H- or 14C-labelled, but usually 3H-phenylalanine) amino acids using the flooding dose technique of Garlick et al [27] (see reviews by Houlihan et al [28] and Fraser and Rodgers [29] for application in fishes). The wide application of the flooding dose technique using 3Hphenylalanine across a range of non-human taxa enables direct comparison of data between studies within and across taxa [26, 28, 29], the drawback of this technique is that it provides a single terminal measure of protein synthesis precluding any studies of broad sense repeatability and so conclusions drawn on inter-individual differences in physiological performance are based on a single measure. Despite the use of repeated measures of protein synthesis using stable isotopes in mammalian studies (op. cit.) and in some ectotherm studies (e.g. Mytilus edulis [37]; Platichthys flesus, [38]), broad sense repeatability, per se, has not been quantified

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