Transcriptome analysis reveals novel insights into the response of low-dose benzo(a)pyrene exposure in male tilapia

• Published in: Aquatic toxicology 2018-08, Vol.201, p.162-173
• Main Authors: Colli-Dula, Reyna Cristina, Fang, Xiefan, Moraga-Amador, David, Albornoz-Abud, Nacira, Zamora-Bustillos, Roberto, Conesa, Ana, Zapata-Perez, Omar, Moreno, Diego, Hernandez-Nuñez, Emanuel
• Format: Article
• Language: English
• Subjects: Benzo(a)pyrene; RNA-Seq; Tilapia; Transcriptomics
• ISSN: 0166-445X; 1879-1514
• DOI: 10.1016/j.aquatox.2018.06.005

•High-throughput RNA-Seq was used to gain a better insight into the mechanism of BaP toxicity in a non-model organism such as tilapia.•BaP exposure in the short-term causes negative effects on morphometric endpoints related to general health and reproduction in male talapia.•New pathways implicated in BaP toxicity such androgen receptor coregulator ARA55 were identified in tilapia, a non-model organism.•Low repeated BaP exposure can activate metabolic and signaling pathways that might have a role in promoting carcinogenesis and compromising reproductive success in male adult tilapia.•Low repeated BaP exposure causes molecular and biological responses that are indicators of diminished heath and reproduction capacity of tilapia. Despite a wide number of toxicological studies that describe benzo[a]pyrene (BaP) effects, the metabolic mechanisms that underlie these effects in fish are largely unknown. Of great concern is the presence of BaP in aquatic systems, especially those in close proximity to human activity leading to consumption of potentially contaminated foods. BaP is a known carcinogen and it has been reported to have adverse effects on the survival, development and reproduction of fish. The purpose of this study was to investigate if a low dose of BaP can alter genes and key metabolic pathways in the liver and testis in male adult tilapia, and whether these could be associated with biological endpoints disruption. We used both high-throughput RNA-Sequencing to assess whole genome gene expression following repeated intraperitoneal injections of 3 mg/kg of BaP (every 6 days for 26 days) and morphometric endpoints as indicators of general health. Condition factor (K) along with hepatosomatic and gonadosomatic indices (morphometric parameters) were significantly lower in BaP-treated fish than in controls. BaP exposure induced important changes in the gene expression pattern in liver and testis as revealed by both Pathway and Gene Ontology (GO) analyses. Alterations that were shared by both tissues included arachidonic acid metabolism, androgen receptor to prostate-specific antigen signaling, and insulin-associated effects on lipogenesis. The most salient liver-specific effects included: biological processes involved in detoxification, IL6-associated insulin resistance, mTOR hyperactivation, mitotic cytokinesis, spindle pole and microtubule binding. BaP effects that were confined to the testis included: immune system functions, inflammatory response, estr