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19 September 2012 Changes in muscle composition during the development of diving ability in the Australian fur seal
Domenic A. LaRosa, David J. Cannata, John P. Y. Arnould, Lynda A. O’Sullivan, Rod J. Snow, Jan M. West
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Abstract

During development the Australian fur seal transitions from a terrestrial, maternally dependent pup to an adult marine predator. Adult seals have adaptations that allow them to voluntarily dive at depth for long periods, including increased bradycardic control, increased myoglobin levels and haematocrit. To establish whether the profile of skeletal muscle also changes in line with the development of diving ability, biopsy samples were collected from the trapezius muscle of pups, juveniles and adults. The proportions of different fibre types and their oxidative capacity were determined. Only oxidative fibre types (Type I and IIa) were identified, with a significant change in proportions from pup to adult. There was no change in oxidative capacity of Type I and IIa fibres between pups and juveniles but there was a two-fold increase between juveniles and adults. Myoglobin expression increased between pups and juveniles, suggesting improved oxygen delivery, but with no increase in oxidative capacity, oxygen utilisation within the muscle may still be limited. Adult muscle had the highest oxidative capacity, suggesting that fibres are able to effectively utilise available oxygen during prolonged dives. Elevated levels of total creatine in the muscles of juveniles may act as an energy buffer when fibres are transitioning from a fast to slow fibre type.

© CSIRO 2012
Domenic A. LaRosa, David J. Cannata, John P. Y. Arnould, Lynda A. O’Sullivan, Rod J. Snow, and Jan M. West "Changes in muscle composition during the development of diving ability in the Australian fur seal," Australian Journal of Zoology 60(2), 81-90, (19 September 2012). https://doi.org/10.1071/ZO11072
Received: 14 September 2011; Accepted: 1 July 2012; Published: 19 September 2012
JOURNAL ARTICLE
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KEYWORDS
creatine
Skeletal muscle
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