Stressor-specific induction of heat shock protein 70 in the freshwater prawn Macrobrachium malcolmsonii (H. Milne Edwards) exposed to the pesticides endosulfan and carbaryl

Agricultural run off that is contaminated with pesticides enters water bodies, thereby polluting the aquatic environment. The sensitivity of the freshwater prawn, Macrobrachium malcolmsonii, to such pesticides is well-documented. However, the stress response to sublethal concentrations of pesticides has scarcely been investigated. In the present study, the effect of two different sublethal concentrations (1/5th and 1/10th of LC50 value) of endosulfan and carbaryl on the synthesis of hsp70 in various tissues of the prawn M. malcolmsonii was evaluated by Western blotting analysis. Among the tissues analyzed (gill, skeletal muscle, and hepatopancreas), induction of hsp70 synthesis was recorded only in the gill tissue of the prawns that had been exposed to either the high or low sublethal concentration of endosulfan. Induction of synthesis of hsp70 was not observed in any of the tissues sampled from the prawns that had been exposed to either the low or the high sublethal concentration of carbaryl. Pesticides interfere with the hydrophobic core of protein, thus leading to denaturation of the protein by exposing the lipophilic moieties to the aqueous environment. Specific induction of hsp70 in the gill possibly occurred since the gill is the route of exposure for pesticides in the prawns. The absence of induction of hsp70 synthesis in prawns that had been exposed to carbaryl suggests that induction of hsp70 synthesis is stressor-specific.