Haemocyte Apoptosis of the Tiger Shrimp Penaeus monodon Exposed to Cadmium

This study investigated the effect of ambient Cadmium (Cd) on haemocyte apoptosis of the shrimp, Penaeus monodon. Cellular response was determined in Cd-exposed (0, 0.05, 0.5 and 5 mg L−1) shrimp. Results showed that 0.05 mg L−1 Cd2+ had no significant effect on the haemocyte parameters during the 48 h exposure. Cadmium at doses of 0.5 and 5 mg L−1 depressed the total haemocyte count (THC), and increased reactive oxygen species (ROS) production and apoptosis ratio in haemocytes. Esterase activity increased in shrimp exposed to 0.5 mg L−1 Cd2+ for 6 h, and decreased to the initial level later. Depressed esterase activity could be observed in shrimp after 24 and 48 h exposure to 5 mg L−1 Cd2+. These results demonstrated that Cd2+ modified esterase activity and induced ROS generation, which led to haemocyte apoptosis and THC reduction. Oxidative stress is one of the induction mechanisms for Cd-caused apoptosis of shrimp haemocytes.