Early temperature effects on
muscle growth dynamics and histochemical profile of muscle fibres of sea
bass Dicentrarchus labrax L., during larval and juvenile stages
O. López-Albors, M.D. Ayala, F. Gil, A. García-Alcázar,
E. Abellán, R. Latorre, G. Ramírez-Zarzosa, J.M. Vázquez-2003
Aquaculture, 220(1-4): 385-406
Abstract:
Recently, it has been found that the thermal
experience during the earliest phases of development could determine the
larval and postlarval growth characteristics of teleosts. In order to
investigate the effects of the early temperature regime on the advanced
stages of growth of sea bass, Dicentrarchus labrax L., this species
was reared during the vitelline phase at two temperatures: natural
temperature (@15 °C) and 17.7±0.1 °C, and then larvae
transferred to common temperature (natural temperature). Muscle growth was
studied by morphometric and histochemical techniques (mATPase and NADH-TR).
Body length and body mass were also measured. During the vitelline phase,
muscle growth was similar in both experimental groups, but at 25 days, both
hypertrophy and hyperplasia of white muscle fibres were greater in the
prewarmed group (p<0.05). At the end of metamorphosis (80 days)
and at 120 days, the average diameter of white muscle fibres, as well as the
body length, were greater in the prewarmed group (p<0.05), but the
number of white fibres did not differ significantly between groups. The
morphological mosaic of white muscle fibres was observed at the end of
metamorphosis, and the histochemical mosaic appeared gradually since the
early postlarval stages. Thus, at 120 days, some specimens in both
experimental groups showed three or four different mATPase staining white
fibres: low (L), moderate (M), high (H) and/or very high (vH), whereas in
other specimens, only L or M mATPase activity fibres were observed. Early T
influenced the histochemical maturity of the white muscle. By 120 days, the
proportion of H and vH fibres was greater in the prewarmed group (p=0.027;
p=0.051, respectively). By 154 days, the four mATPase staining
profiles (L, M, H, vH) were observed in all specimens of both groups, but
the proportion of vH fibres was still higher in the prewarmed group. By 188
days, 3774 °C-day for the prewarmed group and 3759 °C-day for the natural
temperature group, only slight differences between groups were observed in
the histochemical properties and no differences were found in the number and
size of white muscle fibres, neither in the body length and body mass of
specimens.
In conclusion, a slight increase of temperature
during the vitelline phase of sea bass increased the muscle growth and body
length of fish in subsequent larval and postlarval stages, and advanced the
histochemical maturity of the white muscle.
(Anatomía
y Embriología, Fac. Veterinaria, Universidad de Murcia, Murcia 30100,
Spain, e-mail : albors@um.es)