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The Role of Epigenomics in Aquatic Toxicology
Brander, S., A. Biales, AND R. Connon. The Role of Epigenomics in Aquatic Toxicology. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY. Society of Environmental Toxicology and Chemistry, Pensacola, FL, 36(10):2565–2573, (2017).
The pivotal role played by the epigenome in orchestrating the expression of genes that drive cellular differentiation and the response to environmental change (e.g. temperature, nutrition, pollution) is now undisputed. The epigenome is a suite of mitotically and / or meioticallyheritable changes in gene function that occur via mechanisms other than direct changes in DNA sequence. Epigenetic regulation of gene function is associated with a wide variety of mechanisms that both positively or negatively impact gene transcription or the production of protein products. Some of the more well‐known mechanisms include DNA methylation and modification of histones through the methylation or acetylation of lysine residues. Functional groups added to specific regulatory regions of DNA, either upstream of genes or bound to the tails of histones that provide DNA’s framework, dictate which regions of coding DNA are accessible to transcriptional machinery. Epigenetics involves the reduction or prevention of transcription via methylation of cytosine nucleobases in regulatory regions, as well as either decreased or increased transcription via methylation or acetylation of lysine in histone tails, respectively. The processes of histone modification and DNA methylation are directed by and transcripts can be deactivated prior to translation by short stranded non‐coding RNAs (Allis and Jenuwein, 2016).
Over the past decade, the field of molecular biology has rapidly incorporated epigenetic studies to evaluate organism–environment interactions that can result in chronic effects. Such responses arise from early life stage stress, the utilization of genetic information over an individual's life time, and transgenerational inheritance. Knowledge of epigenetic mechanisms provides the potential for a comprehensive evaluation of multigenerational and heritable effects from environmental stressors, such as contaminants. Focused studies have provided a greater understanding of how many responses to environmental stressors are driven by epigenetic modifiers. We discuss the promise of epigenetics and suggest future research directions within the field of aquatic toxicology, with a particular focus on the potential for identifying key heritable marks with consequential impacts at the organism and population levels.