title: Characterisation of transcriptional responses to dioxins and dioxin-like contaminants in roach (Rutilus rutilus) using whole transcriptome analysis.
abstract: There is significant concern regarding the contamination of riverine sediments with dioxins and dioxin-like compounds (DLCs), including polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs) and some polycyclic aromatic hydrocarbons (PAHs). The majority of studies investigating the ecotoxicology of DLCs in fish have focused on a few standard model species. However, there is significant uncertainty as to whether these model species are representative of native river fish, particularly in Europe. In this study, the transcriptional responses following exposure to equipotent concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), PCB 156 or the dioxin-like PAH, benzo[k]fluoranthene (BkF), were investigated in juvenile roach (Rutilus rutilus), a fish species that constitutes a large proportion of the fish biomass in freshwater bodies throughout Europe. To this end, RNA sequencing analysis was used to comprehensively characterise the molecular mechanisms and pathways of toxicity of these DLCs. Whole transcriptome analyses using ClueGO software revealed that DLCs have the potential to disrupt a number of important processes, including energy metabolism, oogenesis, the immune system, apoptosis and the response to oxidative stress. However, despite using equipotent concentrations, there was very little conservation of the transcriptional responses observed in fish exposed to different DLCs. TCDD provoked significant specific changes in the levels of transcripts related to immunotoxicity and carbohydrate metabolism, while PCB 156 caused virtually no specific effects. Exposure to BkF affected the most diverse suite of molecular functions and biological processes, including blood coagulation, oxidative stress responses, unspecific responses to organic or inorganic substances/stimuli, cellular redox homeostasis and specific receptor pathways. To our knowledge, this is the first study of the transcriptome-wide effects of different classes of DLCs in fish. These findings represent an important step towards describing complete toxicity pathways of DLCs, which will be important in the context of informing risk assessments of DLC toxicity in native fish species.
authors.affiliation: Department of Ecosystem Analysis, Institute for Environmental Research, ABBt - Aachen Biology and Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Brinkmann
authors.affiliation: Department of Ecosystem Analysis, Institute for Environmental Research, ABBt - Aachen Biology and Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Koglin
authors.affiliation: Toxicology Centre, University of Saskatchewan, 44 Campus Drive, Saskatoon, SK S7N 5B3, Canada.
authors.forename: Bryanna
authors.initials: B
authors.lastname: Eisner
authors.affiliation: Toxicology Centre, University of Saskatchewan, 44 Campus Drive, Saskatoon, SK S7N 5B3, Canada.
authors.forename: Steve
authors.initials: S
authors.lastname: Wiseman
authors.affiliation: Toxicology Centre, University of Saskatchewan, 44 Campus Drive, Saskatoon, SK S7N 5B3, Canada; School of the Environment & Sustainability, University of Saskatchewan, 44 Campus Drive, Saskatoon, SK S7N 5B3, Canada.
authors.forename: Markus
authors.initials: M
authors.lastname: Hecker
authors.affiliation: Department of Ecosystem Analysis, Institute for Environmental Research, ABBt - Aachen Biology and Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Eichbaum
authors.affiliation: Department of Ecosystem Analysis, Institute for Environmental Research, ABBt - Aachen Biology and Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany.
authors.forename: Beat
authors.initials: B
authors.lastname: Thalmann
authors.affiliation: Federal Institute of Hydrology (BfG), Department G3: Biochemistry, Ecotoxicology, Am Mainzer Tor 1, 56068 Koblenz, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Buchinger
authors.affiliation: Federal Institute of Hydrology (BfG), Department G3: Biochemistry, Ecotoxicology, Am Mainzer Tor 1, 56068 Koblenz, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Reifferscheid
authors.affiliation: Department of Ecosystem Analysis, Institute for Environmental Research, ABBt - Aachen Biology and Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany; College of Resources and Environmental Science, Chongqing University, 1 Tiansheng Road Beibei, Chongqing 400715, China; College of Environmental Science and Engineering, State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, 1239 Siping Road, Shanghai, China; State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, China. Electronic address: henner.hollert@bio5.rwth-aachen.de.
authors.forename: Henner
authors.initials: H
authors.lastname: Hollert
mesh_terms: D000818:Animals; D001572:Benzofurans / Q000633:toxicity*; D003530:Cyprinidae / Q000502:physiology*; D000072338:Dibenzofurans, Polychlorinated; D004147:Dioxins / Q000633:toxicity*; D004785:Environmental Pollutants / Q000633:toxicity*; D005060:Europe; D015870:Gene Expression / Q000187:drug effects*; D020869:Gene Expression Profiling
chemical_list: D001572:Benzofurans; D000072338:Dibenzofurans, Polychlorinated; D004147:Dioxins; D004785:Environmental Pollutants; C020887:dibenzo(1,4)dioxin
keywords: Aryl hydrocarbon receptor; ClueGO; Illumina sequencing; Next-generation sequencing; RNAseq; Transcriptomics