CONTROL OF REPRODUCTION AND THE DEVELOPMENT OF EPIGENETIC BIOMARKERS TO ASSESS KEY PERFORMANCE TRAITS IN AQUACULTURE

The management of reproduction is essential in modern aquaculture, and one of the most important aspects is to have the right proportion of sexes. Sex control, therefore, serves different purposes (see table): in many aquacultured fish and crustacean species there is a clear sexual dimorphism in growth and ultimate size, whereby one sex grows faster than the other or attains a larger size. Thus, there is a clear economic benefit by culturing only the fastest-growing sex. Also, in some species precocious maturation and uncontrolled reproduction need to be prevented. Further, negative impacts of reproduction on product quality or disease resistance need also to be prevented in some species. Finally, in sex‐changing hermaphrodites sex ratio control can benefit broodstock management. In this talk, the latest developments in sex determination and control will be discussed.

Furthermore, traditional breeding practices in both plant and animal production have relied on different forms of genetic selection. However, it has become apparent that there can be phenotypic variance in traits of interest that cannot be explained by the traditional genetic x environmental (GxE) interaction alone. Epigenetics can be defined as the study of phenomena and mechanisms that cause temporal or permanent heritable changes to gene expression that are not dependent on changes to DNA sequence but that are chromosome-bound. Currently, it is accepted that epigenetics contributes to integrate genomic and environmental information to bring about the phenotype, and that epigenetic variation can account for variation that cannot be explained solely on the genetic basis. There are three major epigenetic mechanisms: DNA methylation, histone modifications and non-coding RNAs. Here, the development of epigenetic biomarkers for animal production, particularly based on DNA methylation, will be discussed. Examples will be given on the use of epigenetic biomarkers to predict sex, to identify hidden effects of suboptimal rearing conditions and to assess the early stages of domestication of fish. Supported by Ministry of Science grant AGL2016-78710-R to FP.