** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** IMPROVEMENTS TO DEVELOPMENTAL COMPETENCE OF BOVINE EMBRYOS IS A HIGH PRIORITY AREA TO INCREASE REPRODUCTIVE EFFICIENCIES. TARGETED APPROACHES TO MODULATE GENE-ENVIRONMENT INTERACTIONS THAT INFLUENCE BLASTOCYST DEVELOPMENT THROUGH CONCEPTUS ELONGATION AND MATERNAL-EMBRYO COMMUNICATION ARE ATTRACTIVE STRATEGIES TO INCREASE PREGNANCY SUCCESS. PEROXISOME-PROLIFERATOR ACTIVATED RECEPTOR GAMMA (PPARG) IS A LIGAND-ACTIVATED NUCLEAR TRANSCRIPTION FACTOR EXPRESSED IN THE BOVINE BLASTOCYST THAT RESPONDS TO FATTY ACID (FA) STIMULATION AND IS ESSENTIAL FOR PLACENTAL FUNCTION AND PREGNANCY MAINTENANCE IN OTHER SPECIES. PPARG REQUIREMENTS FOR BOVINE EMBRYO DEVELOPMENT ARE UNKNOWN.THE OVERALL GOAL OF THIS PROPOSAL IS TO DETERMINE REGULATORY ROLES OF PPARG FOR EMBRYO DEVELOPMENT. OBJECTIVE 1 WILL DETERMINE THE REQUIREMENT OF PPARG FOR BLASTOCYST FORMATION AND CELL LINEAGE SPECIFICATION WHILE OBJECTIVE 2 WILL DEFINE DEVELOPMENTAL AND TRANSCRIPTOMIC ROLES OF PPARG IN RESPONSE TO EMBRYO FA AVAILABILITY. OBJECTIVE 3 WILL DETERMINE ROLES OF EMBRYONIC PPARG IN RESPONSE TO MATERNAL FA AVAILABILITY FOR CONCEPTUS ELONGATION. AN EXPERIMENTAL MODEL CONSISTING OF PPARG KNOCKOUT EMBRYOS AND SUPPLEMENTATION OF FA TO EMBRYO CULTURE AND COW DIETS FOR EMBRYO TRANSFER WILL DETERMINE DEVELOPMENTAL, TRANSCRIPTOMIC, AND MORPHOLOGICAL CHARACTERISTICS REGULATED BY PPARG. FUNCTIONS IN MATERNAL-EMBRYO COMMUNICATION WILL BE QUANTIFIED BY TARGETED TRANSCRIPTOME ANALYSES OF THE ENDOMETRIUM.RESULTS FROM THESE STUDIES WILL POSITIVELY IMPACT THE CATTLE INDUSTRY BY PROVIDING GUIDANCE FOR EMBRYO REQUIREMENTS THAT IMPROVE EARLY DEVELOPMENT SUCCESS. THIS PROPOSAL SPECIFICALLY ADDRESSES PROGRAM PRIORITY AREA A1211 - CELLULAR, MOLECULAR, GENOMIC AND WHOLE ASPECTS RELEVANT TO IMPROVING REPRODUCTIVE EFFICIENCY AND THE SUB-PRIORITY AREA EMBRYONIC AND FETAL DEVELOPMENT (INCLUDING INTERACTION BETWEEN THE CONCEPTUS AND ITS UTERINE ENVIRONMENT).