OVER THE PAST SEVERAL DECADES, ANIMAL GENETICISTS HAVE DISCOVERED HOW DNA SEQUENCE INFLUENCES GROWTH, MEAT QUALITY, AND OTHER ECONOMICALLY IMPORTANT TRAITS IN THE PIG, THEREBY IMPROVING GENETIC SELECTION AND PORK PRODUCTION. IT IS NOW RECOGNIZED THAT OTHER NATURAL MODIFICATIONS TO DNA THAT DO NOT ALTER SEQUENCE PLAY EQUALLY IMPORTANT ROLES IN REGULATING ORGANISM FUNCTION. THESE 'EPIGENETIC' MODIFICATIONS ALTER THE ARCHITECTURE OF DNA, DETERMINING WHICH GENES ARE ABLE TO BE EXPRESSED IN A GIVEN CELL. DNA METHYLATION IS THE MOST WELL-STUDIED EPIGENETIC MODIFICATION AND IS FOUND IN ALL MAMMALIAN TISSUES THROUGHOUT DEVELOPMENT, DEMONSTRATING ITS IMPORTANCE IN REGULATING NEARLY ALL BIOLOGICAL PROCESSES. FEW DNA METHYLATION STUDIES HAVE BEEN CONDUCTED IN THE PIG, LIMITING OUR UNDERSTANDING OF HOW THIS PROCESS INFLUENCES EXPRESSION OF GENES THAT CONTROL ECONOMICALLY IMPORTANT TRAITS.THE MAJOR GOALS OF THIS PROJECT ARE TO PROFILE DNA METHYLATION PATTERNS IN OVER TWO DOZEN ADULT PIG TISSUES THAT INFLUENCE GROWTH, MEAT QUALITY, AND STRESS TOLERANCE; ADDITIONALLY, WE WILL ASSESS DNA METHYLATION IN FOUR CRITICAL TISSUES IN DEVELOPING PIG FETUSES (BRAIN, LIVER, SKELETAL MUSCLE, AND PLACENTA). WE WILL USE DNA SEQUENCING TECHNOLOGIES TO CALCULATE THE DEGREE OF DNA METHYLATION ACROSS SITES IN THE PIG GENOME IN EACH TISSUE. WE ARE MOST INTERESTED IN IDENTIFYING SITES WHERE DNA METHYLATION IS DYNAMIC ACROSS TISSUES AND DEVELOPMENTAL STAGES, SINCE THESE SITES ARE LIKELY PLAYING IMPORTANT ROLES IN GENE REGULATION THAT ARE IMPORTANT FOR TISSUE-SPECIFIC FUNCTIONS OR FOR DEVELOPMENTAL PROGRESSION. THIS INCREASED UNDERSTANDING OF GENE REGULATION--ESPECIALLY REGULATION OF GENES THAT INFLUENCE ECONOMICALLY IMPORTANT TRAITS IN THE PIG--WILL ULTIMATELY LEAD TO A BETTER UNDERSTANDING OF HOW THE GENOME INFLUENCES ANIMAL PERFORMANCE, AND GUIDE FUTURE PIG BREEDING PRACTICES.