Modulation of calcium balance in tilapia larvae (Oreochromis mossambicus) acclimated to low-calcium environments.
This study examined how developing fish larvae regulate their Ca2+ balance for acclimation to low ambient Ca2+. Calcium balance in newly hatched larvae was examined individually. Developing larvae not only increased Ca2+ influx but also decreased Ca2+ efflux when they were acclimated to low-Ca2+ environments. After acclimation for 8 days, the influx and efflux of the low-Ca2+ (0.02 mM) group were about 106% and 43%, respectively, compared to those of the high-Ca2+ (1.0 mM) group. Sensitivity and response to low-Ca2+ environments are age-dependent. Upon acute exposure to low Ca2+. newly hatched (H0) larvae increased both Ca2+ influx (from 24% to 67% of high-Ca2+) and net uptake (from 5% to 69%) within 64 h, while 3-day-posthatching (H3) larvae managed to reach the levels of the control within 38 h. Declining Ca2+ efflux in H3 larvae occurred 14 h after exposure, much faster than those in H0 larvae (38 h). It is suggested that modulation of Ca2+-balance mechanisms in developing larvae is dependent upon the levels of Ca2+ in the larval body.
Chou
M Y
MY
Department of Biology, Tunghai University, Taichung, Taiwan, ROC.
Yang
C H
CH
Lu
F I
FI
Lin
H C
HC
Hwang
P P
PP
D000222:Adaptation, Physiological / Q000502:physiology*; D000818:Animals; D002118:Calcium / Q000493:pharmacokinetics*; D004777:Environment; D006706:Homeostasis / Q000502:physiology; D007814:Larva / Q000378:metabolism; D017210:Tilapia / Q000254:growth & development / Q000378:metabolism*
D002118:Calcium