N. Jonathan Walesby

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The metabolic and structural differentiation of locomotory muscles of Notothenia rossii has been investigated. In this species sustained locomotion is achieved by sculling with enlarged pectoral fins (labriform locomotion), whilst the segmental myotomal muscle is reserved for burst activity. Red, white and subepidermal fibres can be distinguished in the(More)
Studies have been carried out on the Mg2+ Ca2+-myofibrillar ATPase from the muscles of fish adapted to different environmental temperatures. The thermal stability of the ATPase is strongly correlated with mean habitat temperature. Activities of Antarctic fish ATPases are significantly higher at low temperatures than those of temperate and tropical water(More)
Previous studies on fish Mg2+Ca2+ activated myofibrillar ATPases have been extended to species inhabiting diverse thermal environments. Cold adapted ATPases have considerably higher catalytic centred activities at low temperatures than warm adapted ATPases. Differences in cell temperature have also lead to evolutionary modifications in thermodynamic(More)
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(More)
Actomyosins have been isolated from the white skeletal muscles of fish inhabiting thermal environments with characteristically low seasonal temperature variations for example, Antarctica, arctic rivers and the equatorial oceans. Calcium regulation of actomyosin ATPase was correlated with environmental temperature. Increased assay temperature resulted in a(More)
Cold acclimation in fish is associated with an elevation in metabolic rate. The present study investigates the role of adenine nucleotides and related compounds in metabolic regulation following temperature acclimation. Brook trout (Salvelinus fontinalis) were acclimated for 10 weeks to either +4°C or +24°C. Both groups of fish were exercised at 2.5 body(More)
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