SIGNIFICANT RESEARCH EFFORT CONCERNING IMPROVED EFFICIENCY OF LIVESTOCK PRODUCTION IS OCCURRING AT PUBLIC INSTITUTIONS AND IN PRIVATE COMPANIES AND IT IS IMPERATIVE THAT RESEARCH OF THIS TYPE BE PUBLICLY FUNDED TO ENSURE AVAILABILITY OF RESULTS TO ANIMAL AGRICULTURE AND TO PRIVATE INDUSTRY. THE GREATEST LIMITATION TO REPRODUCTIVE EFFICIENCY ACROSS MAMMALIAN SPECIES IS EMBRYONIC MORTALITY, HOWEVER, THE MOLECULAR MECHANISMS CONTROLLING EMBRYO VIABILITY ARE NOT WELL UNDERSTOOD. SUCCESSFUL DEVELOPMENT IS DEPENDENT UPON THE COORDINATED EXPRESSION OF A SERIES OF GENES WHICH ARE REGULATED IN LARGE PART BY EPIGENETIC MECHANISMS. OUR CENTRAL HYPOTHESIS IS THAT THE NOVEL DNA MODIFICATION, N6-ADENINE METHYLATION(6MA) REPRESENTS APRECISE EPIGENETIC MECHANISM FOR GENE REGULATION FOR NORMAL EMBRYONIC DEVELOPMENT. SPECIFIC OBJECTIVES ARE TO: (1) CHARACTERIZE THE 6MA DYNAMICS IN BOVINE EARLY EMBRYOS; (2) DETERMINE THE ROLE OF ALKBH1 (6MA ERASER) AND N6AMT1 (6MA WRITER) IN THE REMODELING OF 6MA DURING BOVINE EARLY EMBRYOGENESIS; (3) ESTABLISH THE INTERPLAY AND COOPERATIVE ROLE OF 6MA REMODELING AND 5MC (DNA CYTOSINE METHYLATION)DEMETHYLATION DURING BOVINE EARLY EMBRYOGENESIS. THIS PROJECT WILL USE A VARIETY OF STATE-OF-THE-ART APPROACHES INCLUDING HIGHLY SENSITIVE SEQUENCING TECHNOLOGIESPROFILINGTHE DNA MODIFICATIONS, ZYGOTE MICROINJECTION ANDSINGLE CELL RNA SEQUENCINGANALYSES. SUCCESSFUL COMPLETION OF THIS PROJECT WILL ENHANCEOUR KNOWLEDGE OF THE BIOLOGICAL FUNCTION OF THE NOVEL EPIGENETIC MECHANISMS INVOLVING 6MA ACROSS THE TREE OF LIFE AND ITS CRITICAL ROLE IN EMBRYO VIABILITY. SUCH FUNDAMENTAL KNOWLEDGE IS CRUCIAL FOR DEVELOPING NEW APPROACHES TO IMPROVE FERTILITY OF AGRICULTURAL IMPORTANT ANIMALS.