Cytotoxicity of nitrite on haemocytes of the tiger shrimp, Penaeus monodon, using flow cytometric analysis

This study was aimed at investigating the cytotoxicity of nitrite on haemocytes of the black tiger shrimp, Penaeus monodon. Total haemocyte count (THC), reactive oxygen species (ROS) production, DNA damaged cell ratio and apoptotic cell ratio of shrimp were determined after exposure to different concentrations of nitrite-N (0, 1, 10 and 20 mg L−1) for 0, 6, 12, 24 and 48 h. There was no significant effect on the analytic indicator of shrimp exposed to 1 mg L−1 nitrite-N. THC decreased after 48 h exposure to 10 mg L−1 nitrite-N, and after 24 h exposure to 20 mg L−1 nitrite-N. Production of ROS was induced after 48 h exposure to 10 mg L−1 nitrite-N, and after 12 h exposure to 20 mg L−1 nitrite-N. The percentage of DNA damaged cell increased in P. monodon following 48 h exposure to 10 mg L−1 nitrite-N, and 24 h exposure to 20 mg L−1 nitrite-N. Apoptotic cell ratio increased after 48 h exposure to 10 mg L−1 nitrite-N, and 12 h exposure to 20 mg L−1 nitrite-N. These results indicated that nitrite-N would induce overproduction of ROS, and then resulted in DNA damage and cell apoptosis, and subsequently caused THC reduction. This process of oxidative stress was one of the toxicity mechanisms of nitrite on shrimp.