We propose to establish a new research project with Dr. Mathavan, Genome Institute of Singapore (GIS) and Dr. Collas (Norway). In this project, we will use zebrafish embryos to survey epigenetic changes and gene regulation during differentiation of stem cells in very early embryos. Stem cells in zebrafish embryos are defined by their ability to give rise to any structure. Blastomere cells pre-gastrulation have this property, and can be subdivided according whether they are pre- or post-activation of the zygotic genome. The Maternal-Zygotic Transition (MZT) is an important stage in embryo development, when transcription of the zygotic genome is first initiated. The MZT is characterised by dynamic changes in post-translational histone modifications, and remethylation of the embryonic genome. Epigenetic changes that occur at the MZT are likely to be conserved between zebrafish and mammals. We plan to combine genome-wide epigenetic and gene expression data during the MZT to uncover how epigenetic factors determine stem cell fate. The results will provide a basis for future determination of environmentally-influenced epigenetic effects on early embryo development, and cancer (which can be contributed to by inappropriate regulation of stem cell genes). A major strength of using zebrafish is that we can analyse the role of epigenetic factors in stem cell differentiation in live embryos. This would not be feasible in mammals, because of the sheer numbers of embryos required and their internal location. We propose to investigate early embryonic stages at the time when epigenetic marks (such as methylation) are erased and replaced, incredibly difficult to do in a mammal but easy to do in fish embryos. The results will help determine how genes interact with the environment in early development. When environmental conditions are suboptimal, pathology can result (e.g. metabolic disorders). The results will also reveal epigenetic pathways controlling stem cell differentiation.