Proteomic analysis of the hepatotoxicity of Microcystis aeruginosa in adult zebrafish (Danio rerio) and its potential mechanisms.

Microcystis aeruginosa is one of the main species of cyanobacteria that causes water blooms. M. aeruginosa can release into the water several types of microcystins (MCs), which are harmful to aquatic organisms and even humans. However, few studies have investigated the hepatotoxicity of M. aeruginosa itself in zebrafish in environments that simulate natural aquatic systems. The objective of this study was to evaluate the hepatotoxicity of M. aeruginosa in adult zebrafish (Danio rerio) after short-term (96 h) exposure and to elucidate the potential underlying mechanisms. Distinct histological changes in the liver, such as enlargement of the peripheral nuclei and sinusoids and the appearance of fibroblasts, were observed in zebrafish grown in M. aeruginosa culture. In addition, antioxidant enzyme activity was activated and protein phosphatase (PP) activity was significantly decreased with increasing microalgal density. A proteomic analysis revealed alterations in a number of protein pathways, including ribosome translation, immune response, energy metabolism and oxidative phosphorylation pathways. Western blot and real-time PCR analyses confirmed the results of the proteomic analysis. All results indicated that M. aeruginosa could disrupt hepatic functions in adult zebrafish, thus highlighting the necessity of ecotoxicity assessments for M. aeruginosa at environmentally relevant densities.