Characterisation of the swimming muscles of two subantarctic Notothenioids.

DANIEL ALFREDO FERNANDEZ; JORGE CALVO,; ALISTAIR JOHNSTON, IAN

SCIENTIA MARINA

Año: 1999 vol. 63 p. 477 - 484

0214-8358

The histochemical characteristics and distribution of muscle fibre types have been investigated in the swimming muscles of the r6balo, Eleginops maclovinus and the lorcho, Patagonotothen tessellata, Subantarctic notothenioids that inhabit the Beagle Channel. The fibre types were differentiated on the basis of glycogen and lipid contents and succinate dehydrogenase and myofibrillar ATPase (mATPase) activities. White, red, intermediate and tonic fibres were presentin the axial muscle of both species. The same fibre types were identified in the pectoral fin adductor muscles, although the intermediate type was absent. The mA TPase technique performed at room temperature (21°C) allowed a good differentiation of fibre types, overcoming the problems found by previous researchers when applying this technique to Antarcticnotothenioids. Four different zones (peripheral, mosaic, main and adjacent to the bone) were found in the adductor profundis muscle. The proportion of the zones varied along the length of the adductor muscle. For both species, the percentage of red fibres found in the axial muscles was less than 5%, indicating that sustained swimming ability is not dependent on thesemuscles. The pectoral muscle mass/carcase mass ratio was significantly greater in E. maclovinus than in P. tessellata, reflecting a greater capacity for sustained swimming using pectoral fins.