The epigenetics of embryo development

Abstract

• A range of stresses experienced by the early embryo can alter the growth trajectory of the fetus and neonate and creates a predisposition to a range of metabolic diseases after birth. These effects limit an organism's capacity to achieve its full genetic potential. • Many of the techniques involved in the various forms of assisted reproductive technologies cause stress to the gametes and early embryo. In general, the more extreme the assisted reproductive intervention, the more severe the effect on the animal's potential. • These stresses appear to primarily act by changing the patterns of gene expression encoded by the epigenetic program created during embryo development. Epigenetics involves a range of mitotically heritable modifications to the structure of chromatin that govern the patterns and levels of gene expression. Each differentiation event occurring in early development involves fundamental changes in the cell's epigenetic settings. Covalent modifications to the cytosine base of DNA, especially within cytosine-guanine dinucleotides, are one of the most important epigenetic mechanisms. • While it is well established that assisted reproductive technologies perturb the epigenetic reprogramming of the early embryo, the molecular basis for this is yet to be fully described or understood. • A greater molecular description and understanding of processes of epigenetic reprogramming is required to allow for adaptation of breeding and assisted reproduction technology programs that allow the full genetic potential of offspring to be realized.