Characterisation of the swimming muscles of two Subantarctic notothenoids

Abstract

SUMMARY:The histochemical characteristics and distribution of muscle fibre types have been investigated in the swimming muscles of the róbalo, 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 present in 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 mATPase 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 Antarctic notothenioids. 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 these muscles. 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.Key words: Subantarctic notothenioids, muscle histochemistry, swimming muscles, myosin ATPase. RESUMEN: CARACTERIZACIÓN DE LOS MÚSCULOS DE LA NATACIÓN DE DOS NOTOTÉNIDOS SUBANTÁRTICOS.-Se investigaron la distribución y las características histoquímicas de los distintos tipos de fibras en los músculos responsables de la natación del róbalo, Eleginops maclovinus y del lorcho, Patagonotothen tessellata, nototénidos subantárticos que habitan las aguas del Canal del Beagle. En base a la distribución y morfología de las fibras y a la aplicación de técnicas histoquímicas se diferenciaron en la musculatura axial de ambas especies fibras blancas, rojas, intermedias y tónicas. En el músculo adductor profundis se encontraron los mismos tipos de fibras mencionadas exceptuando las fibras rosas. La técnica de mATPasa realizada a temperatura ambiente (21°C) permitió diferenciar los distintos tipos de fibras, superando así las dificultades encontradas por otros autores al aplicar esta técnica en nototénidos antárticos. En la musculatura pectoral se diferenciaron 4 zonas: periférica, mosaico, principal y adyacente al hueso cuyas proporciones variaron a lo largo del músculo adductor. El porcentaje de fibras rojas encontrado en la musculatura axial de ambas especies fue bajo, menor al 5%, lo que indica que la natación continuada no depende de la musculatura axial. En E. maclovinus el peso relativo de la musculatura pectoral con respecto al peso de la carcasa fue significativamente más alto que en P. tessellata. Esta diferencia refleja distintos grados de actividad de las aletas pectorales en la natación continuada de ambas especies.Palabras clave: Nototénidos sub...

Pectoral fins of Micropogonias furnieri: a histochemical and ultrastructural study

“…At acid pHs, however, mATPase activity was lower and more unstable in the fibres of the medium zone than in the myotomal fibres (Devincenti et al 2000). In the case (Fernández et al 1999(Fernández et al , 2000. In addition, in turbot, in which there is a zone of fibres that gives a mosaic pattern with no oxidative enzyme activity, the intermediate fibres showed stable mATPase activity.…”

Biogeography and adaptation of Notothenioid fish: Hemoglobin function and globin–gene evolution

“…For example, they have a relatively larger mass of red pectoral musculature and a greater capacity for sustained labriform swimming than other notothenioids (Fernández et al, 1999). The rapidity of their escape response is similar to eurythermal temperate non-notothenioids rather than to Antarctic notothenioids (Fernández et al, 2002) and their resting rates of oxygen consumption place them in an active category in comparison with sympatric non-Antarctic notothenioids (Vanella and Calvo, 2005).…”

Partition of aerobic and anaerobic swimming costs related to gait transitions in a labriform swimmer

“…Pectoral fin movements are powered and controlled by a number of pectoral girdle muscles whereas undulations of the body axis are powered by the segmented myotomal musculature (Kendall et al, 2007). The pectoral girdle muscles in labriform swimmers are mostly red (Westneat and Walker, 1997); however, they also have white components (Davison, 1988;Fernández et al, 1999) indicating anaerobic capacity (Davison, 1988;Schaarschmidt and Jürss, 2003). The myotomal musculature is usually spatially divided into separate regions of red and white fibres (Sänger and Stoiber, 2001).…”

“…The myotomal musculature is usually spatially divided into separate regions of red and white fibres (Sänger and Stoiber, 2001). In labriform swimmers, and other median and paired fin swimmers, the red myotomal musculature may be scarce (Fernández et al, 1999;Martinez et al, 2000) or absent (Davison, 1987;Kronnie et al, 1983).…”