Transcriptional response of yellow perch to changes in ambient metal concentrations - a reciprocal field transplantation experiment. Perca flavescens

Our main objectives wereto investigate the molecular mechanisms involved in metal toxicity and detoxification in the field using juvenile yellow perch subjected to differents levels of this metal exposure. Recent local adaptation to pollution has been evidenced in several organisms inhabiting environments heavily contaminated by metals. Nevertheless, the molecular mechanisms underlying adaptation to high metal concentrations are poorly understood, especially in fishes. Yellow perch (Perca flavescens) populations from lakes in the mining area of Rouyn-Noranda (QC, Canada) have been faced with metal contamination for about 90 years. Here, we examine gene transcription patterns of fish reciprocally transplanted between a reference and a metal-contaminated lake and also fish caged in their native lake. After four weeks, 111 genes were differentially transcribed in metal-naïve fish transferred to the metal-contaminated lake, revealing a plastic response to metal exposure. Genes involved in the citric cycle and beta-oxidation pathways were under-transcribed, suggesting a potential strategy to mitigate the effects of metal stress by reducing energy turnover. However, metal-contaminated fish transplanted to the reference lake did not show any transcriptomic response, indicating a reduced plastic response capability to sudden reduction in metal concentrations. Moreover, the transcription of other genes, especially ones involved in energy metabolism, was affected by caging. Overall, our results highlight environmental stress response mechanisms in yellow perch at the transcriptomic level and support a rapid adaptive response to metal exposure through genetic assimilation. Overall design: Comparison between fish Op and Op→Op using a pairwise design corresponding to the cage experiment in the reference lake Opasatica (Op), comparison between fish Du and Du→Du using a pairwise design corresponding to the cage experiment in the metal contaminated lake Dufault (Du), comparison between fish from reference lake transplanted to the metal contaminated lake (Op→Du) and fish from reference lake caged in their own lake (Op→Op) using pairwise design corresponding to the experiment of metal contamination, comparison between fish from metal contaminated lake transplanted to the reference lake (Du→Op) and fish from the metal contaminated lake caged in their own lake (Du→Du) using pairwise design corresponding to the depuration experiment.