title: Effects of chronic metal exposure on wild fish populations revealed by high-throughput cDNA sequencing.
abstract: Given the inherent variability of aquatic systems, predicting the in situ effects of contaminants on such ecosystems still represents a major challenge for ecotoxicology. In this context, transcriptomic tools can help identify and investigate the mechanisms of toxicity beyond the traditional morphometric, physiological and population-level endpoints. In this study, we used the 454 sequencing technology to examine the in situ effects of chronic metal (Cd, Cu) exposure on the yellow perch (Perca flavescens) transcriptome. Total hepatic mRNA from fish sampled along a polymetallic gradient was extracted, reverse transcribed, labeled with unique barcode sequences and sequenced. This approach allowed us to identify correlations between the transcription level of single genes and the hepatic concentrations of individual metals; 71% of the correlations established were negative. Chronic metal exposure was thus associated with a decrease in the transcription levels of numerous genes involved in protein biosynthesis, in the immune system, and in lipid and energy metabolism. Our results suggest that this marked decrease could result from an impairment of bile acid metabolism by Cd and energy restriction but also from the recruitment of several genes involved in epigenetic modifications of histones and DNA that lead to gene silencing.
authors.affiliation: Institut National de La Recherche Scientifique, INRS-Centre Eau Terre Environnement, 490 de la Couronne, Quebec, QC, G1K 9A9, Canada.
authors.forename: Fabien
authors.initials: F
authors.lastname: Pierron
authors.forename: Eric
authors.initials: E
authors.lastname: Normandeau
authors.forename: Michel Amery
authors.initials: MA
authors.lastname: Defo
authors.forename: Peter G C
authors.initials: PG
authors.lastname: Campbell
authors.forename: Louis
authors.initials: L
authors.lastname: Bernatchez
authors.forename: Patrice
authors.initials: P
authors.lastname: Couture
mesh_terms: D000818:Animals; D001647:Bile Acids and Salts / Q000378:metabolism; D002104:Cadmium / Q000032:analysis / Q000378:metabolism / Q000633:toxicity; D003300:Copper / Q000032:analysis / Q000378:metabolism / Q000633:toxicity; D018076:DNA, Complementary; D029941:Fish Proteins / Q000235:genetics / Q000378:metabolism; D005399:Fishes / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D020869:Gene Expression Profiling; D059014:High-Throughput Nucleotide Sequencing; D008670:Metals / Q000032:analysis / Q000378:metabolism / Q000633:toxicity*; D014801:Vitamin A / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism / Q000633:toxicity*
chemical_list: D001647:Bile Acids and Salts; D018076:DNA, Complementary; D029941:Fish Proteins; D008670:Metals; D014874:Water Pollutants, Chemical; D002104:Cadmium; D014801:Vitamin A; D003300:Copper