Calcium is very important for the normal development, growth and survival of most vertebrates. Therefore, regulation of calcium intake and disposal is well-controlled. Mammals obtain most of their calcium from the diet, whereas fish obtain calcium by absorbing it from the external environment. For adults, this occurs in the gills and for larvae it is absorbed through the skin. What this means is that fish living in low calcium environments can acclimate by increasing the absorption of calcium from the water.
Dr. Kwong (Dept. of Biology, Univ. Ottawa, Canada) and colleagues published new research in the American Journal of Physiology showing that a calcium sensing receptor (CaSR) is able to detect variations in the environmental availability of calcium allowing zebrafish larva (Danio rerio) to alter calcium uptake. Four days after fertilization, the researchers acclimated some larva to a low calcium environment (25 uM calcium vs normal environmental concentrations of 250 uM calcium) and found that expression of the CaSR increased. When they experimentally reduced the expression of CaSR, the larvae lost their ability to regulate whole body calcium levels in a low calcium environment.
, , Involvement of the calcium-sensing receptor in calcium homeostasis in larval zebrafish exposed to low environmental calcium. A