Effect of Heavy Metal Cadmium on Total Protein Content, Amino Acid Content and Alanine Aminotransferase Activity of Freshwater Snail, Pila globosa

Abstract

Adult freshwater snails Pila globosa (Gastropod, Ampullariidae) were exposed for a six-day period in laboratory conditions to cadmium toxicity. The effect on the total protein content, amino acid content and activity of alanine aminotranferase (ALT) with increase in the treatment period were calculated. A remarkable decrease in the protein content (Control 74.01; 48hrs 59.99; 96hrs 56.49; 144hrs 50.03 mg/ml/gm wet wt. tissue) and a significant increase in amino acid content have been recorded for each treatment period (48hrs 18.01; 96hrs 25.76; 144hrs 31.36 mg/ml/gm wet wt. tissue) in comparison to control (8.43 mg/ml/gm wet wt. tissue). Cadmium was found to have a synergistic effect on activity of ALT. The activity of ALT significantly increases with increase in the treatment period (48hrs 0.0007; 96hrs 0.0016; 144hrs 0.0035 unit/ml/min) as compared to the control (0.0004 unit/ml/min). The results clearly suggested that under the toxicity stress of the heavy metal cadmium, proteins are gradually degraded into their corresponding amino acids. The increased ALT activity with increase in amino acid content is a clear indication of transamination reaction where corresponding keto acids are formed from amino acids that ultimately enters the citric acid cycle in which electrons are abstracted. Electrons are carried by NADH and FADH2 which are funnelled into a chain of mitochondrial electron carrier reducing O2 TO H2O. This electron drives the production of ATP which is required by the treated snails to meet their high energy demand during the heavy metal stress.