Muscle growth in Antarctic and sub-Antarctic Notothenioid fishes

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

SCIENTIA MARINA

Institut de Ciences del Mar

Lugar: Barcelona; Año: 2005 vol. 69 p. 325 - 335

0214-8358

Muscle growth in Antarctic and sub-Antarctic Notothenioid fishes Summary The suborder Notothenioidei comprises 122 species divided in 8 families, with members of 6 of the families living outside Antarctic waters. The Antarctic species underwent an extensive radiation from a small demersal ancestor to occupy different ecology niches and levels in the water column.  The axial muscle of Antarctic and some sub-Antarctic Notothenioids is unusual in containing very large diameter muscle fibers and a low muscle fiber number. Maximum fiber diameters are greater than 500 μm in many species. There is no indication of systematic differences in fiber number, fiber type composition, ATPase activity, time of cessation of fiber recruitment (hyperplasia) and swimming performance between Antarctic and sub-Antarctic species. Instead, fiber number is significantly decreased in species belonging to the most derived families relative to the more basal families (a trend that also correlates with an increase in the diameter of the fibers). The length of the cell cycle of the muscle fibers shows cold compensation in the Antarctic species H. antarcticus relative to the closely related sub-Antarctic one (H. bispinis). Feeding after a starvation period results in a strong stimulation of the proliferation of muscle fiber progenitors in H. bispinis, but similar studies have not yet been performed on any Antarctic species.