Influence of Polluted Sea Water in the Red Sea on the Osteoclasts and Osteoblasts of Goldfish, Carassius auratus

To analyze the influences of environmental pollutants and bioactive substances on fish bone metabolism, we have developed an original in vitro bioassay using goldfish scales that have osteoclasts, osteoblasts, and bone matrix. We used tartrate-resistant acid phosphatase (TRAP) for osteoclasts and alkaline phosphatase (ALP) for osteoblasts as respective markers. Using this assay system, we have reported the influences of heavy metals such as cadmium (Cd) and mercury (Hg) on fish bone metabolism. In the case of Cd, we found that its concentration (even at 10^-13M) influenced osteoclastic activity in goldfish scales only at 6 hrs of incubation. Thus, in the present study, we examined the effects of polluted seawater on osteoclastic and osteoblastic activities with this scale in vitro bioassay. Polluted seawater was collected from the Suez Gulf site on the Red Sea. Polluted seawater was added into culture medium at dilution rates of 50, 100, and 500 times and incubated with the goldfish scales for 6 hrs. Subsequently, the influences of polluted seawater on TRAP and ALP activities were compared with that of artificial seawater as a non-polluted seawater. As a result, TRAP activity was significantly suppressed by the polluted seawater samples diluted at least 500 times; in contrast, ALP activity did not show any change. This response was similar to the response of Cd and Hg. As heavy metal contamination of the Suez Gulf site has been reported, there is a high possibility that heavy metals are contained in the seawater. Considering our data together with environmental pollution in Egypt that has been reported until now, we should conduct a heavy metal risk assessment to protect the ecosystem in the Red Sea.