Exposure to Prorocentrum minimum Induces Oxidative Stress and Apoptosis in the Ridgetail White Prawn, Exopalaemon carinicauda

Prorocentrum minimum is a bloom-forming, planktonic mixotrophic dinoflagellate, and can cause stress in shrimp ponds. In this study, healthy Exopalaemon carinicauda were exposed to 5 x10(4) cells mL(-1)P. minimum for 72 hours to investigate the adverse effect of P. minimum on shrimps. Elevated superoxide dismutase (SOD) activity and malondialdehyde (MDA) content, reduced total antioxidant capacity (T-AOC) and catalase (CAT) activity, and regulatory glutathione peroxidase (GPX) activity were found in the hemolymph of E. carinicauda after exposure to P. minimum. In this study, P. minimum exposure induced oxidative stress and caused significant oxidative damage to E. carinicauda. P. minimum exposure increased the expression of HSP70 gene in the hemocyte, gills and hepatopancreas. Compared with the enhanced level of caspase-3 gene mRNA in the hemocyte and gills, the up-regulation of caspase-3 gene in the hepatopancreas was only observed from 3 to 6 h, and then the mRNA level of glutathione-S-transferase (GST) gene increased. These results indicated that GST might be involved in the shrimp hepatopancreas' defense against P. minimum exposure. The present study demonstrates that exposure to P. minimum could induce oxidative stress and apoptosis in E. carinicauda. The SOD activity, HSP70 and GST (in the hepatopancreas) were evoked to protect cells from oxidative stress and apoptosis. This study will provide new insights into the toxic mechanism of P. minimum on shrimps.