Metabolic depression and whole-body response to
enforced starvation by Crassostrea gigas postlarvae
Z.
García-Esquivel, V.M. Bricelj, H. Felbeck-2002
Comparative
Biochemistry and Physiology - Part A, 133: 63–77
Abstract:
Physiological
and biochemical measurements were performed on six oyster (Crassostrea
gigas) cohorts, in order to: (a) investigate the whole-body response
(growth, energy content, metabolic and excretion rates) of 2-week-old
postlarvae (spat) to enforced (0–8 days) starvation, and (b) test the
potential use of three aerobic enzyme systems as indices of physiological
condition. Starvation resulted in exponential reduction of postlarval
metabolic and excretion rates, as well as a linear decrease in enzyme
activity. These response mechanisms effectively limited the loss of
endogenous reserves after 2 days of starvation and maintained the oyster’s
functional integrity over prolonged (8 days) starvation. Proteins appeared
to be selectively conserved during short-term (2 days) starvation, as
suggested by a decrease in total protein content, while maintaining constant
weight-specific enzyme activity. Postlarvae starved for 2 days exhibited
relatively higher lipid losses, lower mortality and lower metabolism than
metamorphosing stages, thus suggesting a greater buffering capacity to
starvation in the former. The activity of the electron transport system may
be a useful indicator of long-term stress or developmental condition of
oyster postlarvae, while citrate synthase and cytochrome oxidase could be
used as indicators of growth rate. None of these enzyme systems is
recommended as an index of aerobic metabolism during short-term starvation.
(Universidad
Autonoma de Baja California, Instituto de Investigaciones Oceanologicas,
Apdo. Postal 453, Ensenada, Baja California, Mexico, Tel.: +52-6-174-4601;
fax: +52-6- 174-5303, E-mail: sgarcia@uabc.mx)