Toxic effect on tissues and differentially expressed genes in hepatopancreas identified by suppression subtractive hybridization of freshwater pearl mussel (Hyriopsis cumingii) following microcystin-LR challenge.

Microcystins are a family of potent hepatotoxins produced by freshwater cyanobacteria and can cause animal intoxications and human diseases. In this study, the effect of microcystin-LR (MC-LR) on the tissues of freshwater pearl mussel (Hyriopsis cumingii) was evaluated and differentially expressed genes in the hepatopancreas of the mussel exposed to MC-LR were identified. HPLC analysis of cell extracts from various tissues of the mussel indicated that the hepatopancreas had the highest MC-LR levels (55.78 ± 6.73 μg g⁻¹ DW) after 15-day exposure. The MC-LR concentration in gill or muscle was an order of magnitude less than in hepatopancreas or gonad. Subtractive cDNA library was constructed by suppression subtractive hybridization (SSH), and ∼400 positive clones were sequenced, from which 98 high quality sequences were obtained by BLAST analysis. The screening identified numerous genes involved in apoptosis, signal transduction, cytoskeletal remodel, innate immunity, material and energy metabolism, translation and transcription which were extensively discussed. The results of this study add large amount of information to the mussel genome data, and for the first time present the basic data on toxicity effect of MC-LR on mussel.