Integrating Epigenetics into Aquaculture Research

Abstract

Epigenetics is an exciting and fast developing area of biology that deals with the study of changes in gene expression and function that, nevertheless, do not involve alterations of the genotype. These changes can be heritable through cell mitoses and meiosis and thus through individual generations. Three major epigenetic mechanisms that can activate or suppress gene expression are recognized: DNA methylation, modification of chromatin structure through changes in histone proteins, and regulatory processes mediated by small RNAs. Epigenetic changes are being actively studied in some areas of biology such as developmental biology and for its implications in human health, notably in cancer. However, less attention has been paid in other fields, including evolutionary biology, ecology and, pertaining to our interest, animal production. Since epigenetic processes have been found to be responsible for the integration of both biotic and abiotic factors, epigenetics can help to understand how organisms respond a particular environment. In addition, epigenetic variation may explain the phenotypic variation in production-relevant traits observed in farmed populations. Thus, epigenetic variation can be considered in the light of selection programs to increase animal production. Particularly interesting is the link between conditions during early development, where many heritable epigenetic marks are established, and gene function later in life since proper management of these early conditions may contribute to better growth and health of farmed animals. Because of their external fertilization, aquatic animals in general and fish in particular are excellent research subjects where to study epigenetic changes. These various aspects of epigenetics will be discussed. Among others, an example will be provided on how modifications of a major environmental cue such as temperature is integrated through an epigenetic mechanism, ultimately determining phenotypic sex and growth in a production fish