Transcriptional Epigenetic Mechanisms in Aquatic Species

Epigenetic mechanisms not only are involved in the proper development and differentiation of organisms in general but also allow the organism to respond to environmental changes. In this chapter, we will briefly review molecular epigenetic mechanisms that are capable of modulating mRNA abundance at the transcriptional level (DNA methylation and chromatin remodeling through histone modifications), highlighting the complexity of epigenetic regulation of gene transcription. We will pay special attention to the epigenetic mechanisms that modulate key biological functions in aquatic species. The emphasis of this chapter is placed on teleost (bony) fish, the largest vertebrate group characterized by a high degree of phenotypic variation, and aquatic invertebrates including mollusks, arthropods, and sponges. We provide examples of how environmental signals are capable of causing epigenetic modifications to impact phenotypic traits related to metabolism, growth, development, reproduction, and immune response in aquaculture species. We anticipate that an increase in the knowledge of epigenetic mechanisms modulating the appearance of desired phenotypic traits will potentially help in the development of new aquaculture practices that can significantly benefit aquaculture, making it more sustainable and economically viable.