Temperature acclimation of Mg2+Ca2+-myofibrillar ATPase from a cold-selective teleost,Salvelinus fontinalis: a compromise solution

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Abstract
Brook trout (Salvelinus fontinalis, Mitchill) were acclimated over 15 weeks to either +4°C or +24°C. The effects of temperature on myofibrillar Mg2+Ca2+-ATPase activities were investigated. In contrast to goldfish, temperature acclimation does not alter the kinetic properties of the brook trout myofibrillar ATPase. Activation energy (ΔG#) is lower and substrate turnover number is higher than values previously reported for cold-adapted stenotherms. Properties of brook trout ATPase appear to be a compromise enabling function across a broad temperature range. The different strategies of adapting to seasonal temperature variations are briefly discussed.