Biochemical Effects of Cadmium on the Liver of Catfish, Mystus tengara (Ham.)

The present study is aimed to evaluate possible reasons by which cadmium toxicity causes damage to the liver of a freshwater catfish Mystus tengara (Ham.). After 30 days of exposure fish were processed for biochemical studies. Experiments were performed on estimation of total protein, DNA, RNA and enzymes like alkaline phosphatase (ALP) and acid phosphatase (ACP). Results clearly indicate that total protein, DNA and RNA contents were higher in control group than experimental groups (P>0.001 control vs. group III) and declined minimum in the fish treated with cadmium. However, both ALP and ACP activity were maximum in treated groups. The decrease in the total protein content in experimental fish is due to decrease in DNA and RNA contents. However, it is interesting to see that in both experimental groups, both ALP and ACP activity was elevated. It may be due to as both are phosphatases and known to remove the phosphate group (dephosphorylation) at 5' end of DNA and thus preventing DNA from ligating. That is why that DNA content was found to be minimum in Cd groups where both enzymes were elevated. Therefore, low RNA and protein content were observed in experimental fish.