Transcriptome profiling analysis of Mactra veneriformis exposed to BDE-47 by deep sequencing

RNA-seq provided a general overview of the gene expression profiles of the digestive glands of Mactra veneriformis exposed to 2, 2′,4,4′-tetrabromodiphenyl ether (BDE-47, a type of widely used brominated flame retardants). After acclimatization, the animals were then divided randomly into control group and BDE-47 treatment group. In treatment group, the clams were exposed to BDE-47 for 3 days with the nominal concentration of 5μg/L. BDE-47 was first dissolved in DMSO, and then added to aquaria water to achieve a final DMSO concentration of 0.05% v/v. In control group, DMSO was added directly to aquaria water with the final concentration of 0.05% v/v. Three replicates of control and treatment were performed. Each replicate contained 30 clams. During the whole experiment, the water was constantly aerated (dissolved oxygen 7.6–8.2 mg/L; pH 8.1; salinity 31; temperature 16 ± 1°C) and changed daily. The clams were fed 2 h before the water change, and the corresponding concentrations of BDE-47 and DMSO were added after the water change. The digestive gland was sampled after 3 days’ exposure. Digestive glands from 30 clams were dissected and pooled together for RNA extraction.