ALTHOUGH PROPER EPIGENETIC MARKS WITHIN THE PREIMPLANTATION EMBRYO ARE ESSENTIAL FOR NORMAL DEVELOPMENT, REGULATION OF EPIGENETIC MODIFICATIONS DURING EARLY EMBRYOGENESIS IS POORLY UNDERSTOOD. OUR PREVIOUS STUDIES PINPOINT THAT THE OOCYTE-SPECIFIC TET FAMILY GENE (TET3L) IS CRITICAL FOR NORMAL FERTILIZATION BY REGULATING EPIGENETIC CHANGES DURING EARLY EMBRYOGENESIS. UNDERSTANDING THE ACTIONS OF THE TET FAMILY DURING EARLY EMBRYOGENESIS WILL ALLOW US TO EXPAND OUR KNOWLEDGE OF HOW EPIGENETIC MARKS ARE REGULATED DURING EMBRYOGENESIS AND USE THE KNOWLEDGE TO DESIGN NOVEL STEM CELL LINES. WE PROPOSE TO IDENTIFY HOW TET3L AFFECTS CELLULAR SPECIFICATION DURING EMBRYOGENESIS, THE UNIQUENESS OF TET3L AMONG DIFFERENT TET FAMILY MEMBERS, AND THE PATHWAY OF REPROGRAMMING INITIATED BY TET3L. WE WILL APPLY ADVANCED MOLECULAR AND BIOINFORMATIC ANALYSIS TECHNOLOGIES TO OBTAIN THE ANSWERS. THROUGH THIS RESEARCH, WE EXPECT TO ELUCIDATE THE IMPACT OF TET3L ON VARIOUS EPIGENETIC MARKS WHICH WILL BE THEFIRST REPORT IN NON-RODENT SPECIES. UNDERSTANDING THE ACTION OF KEY EPIGENETIC REGULATORS, SUCH AS THE TET FAMILY, DURING EMBRYOGENESIS WILL ALLOW US TO IMPROVE EMBRYO VIABILITY IN DOMESTIC SPECIES AND OFFER A NOVEL APPROACH TO GENERATE STEM CELLS FROM SOMATIC CELLS.