Digital gene expression analysis of reproductive toxicity of benzo[a]pyrene in male scallop chlamys farreri

Abstract

Benzo[a]pyrene (BaP) is a representative polycyclic aromatic hydrocarbon (PAH) and is studied widely for its strong toxicity and wide distribution. Although BaP pollution in marine environment is increasing, molecular mechanisms underlying reproductive toxicity of BaP in marine mollusks have been seldom systematically studied, especially in males. In this study, genes that regulated reproductive responses of Chlamys farreri under BaP stress were analyzed through digital gene expression (DGE) sequencing with testis tissues. A total of 12,485,055 and 14,454,127 clean reads were generated from control and BaP exposure DGE libraries, respectively. After comparing two libraries, 1051 differentially expressed genes were detected, with 223 up-regulated and 828 down-regulated genes. Gene ontology (GO) annotation and kyoto encyclopedia of genes and genomes (KEGG) pathway analyses were performed on all genes to understand their biological functions and processes. The results showed that numerous enriched, differentially expressed genes related to aromatic compound catabolic processes, spermatid development, microtubule-based movement, energy production and immune response. Quantitative real-time PCR was performed to verify the expressed genes of DGE. The study generated data to show the overall reproductive transcription responses of male C. farreri under BaP stress, and it also can serve as the reference for future study of organic pollutions in aquatic mollusks.