Authors: Ghizlane Banousse, Christina Semeniuk, Louis Bernatchez, Céline Audet
Acclimation to high temperatures associated with global climatic change is a vital challenge for cold-adapted fishes such as brook charr (Salvelinus fontinalis). Environmental variation can potentially induce phenotypic changes that are inherited across generations via epigenetic mechanisms that may allow for adaptive rapid responses to changing conditions. Yet, our understanding of epigenetic mechanisms underlying transgenerational plasticity is still limited. In this study, we aimed to determine if epigenetic changes modulating gene expression modifications are associated with transgenerational plasticity. Adults brook charr were exposed to either cold (from 11.5°C in September to 3°C in December) or warm (from 13.5°C in September to 5°C in December) thermal profiles during sexual maturation. Families were produced using a replicated two-by-two breeding design. Eggs from each family were split in two batches, one incubated at 5 °C and the second one at 8°C. The same thermal conditions were maintained from hatching to yolk sac resorption. Using RNA sequencing from brain tissue, we obtained 7881 differentially expressed genes (DGE) between the warm and the cold parental thermal regime. However, offspring incubation temperature had no significant effect on gene expression. Comparing the two parental thermal groups, functions related to neuron development, signal transduction, synapse organization, and heat-stress response were significantly enriched in DGE. 22 genes out of 28 genes from the GEN-FISH STP-Brain chip v2.0 were among the top 500 DGE. The same RNA samples are currently being analyzed with the GEN-FISH STP-Brain chip v2.0, and results from RNA sequencing will be used to test the efficiency of the developed transcriptomics profile array. Our results reinforce the relevance of epigenetic inheritance in response to climate change. Such inheritance may be an important mechanism associated with buffering the effects of global warming in future generations of brook charr.
