THE PRODUCTION EFFICIENCY CAN BE ENHANCED FOR THE CATFISH INDUSTRY THROUGH THE APPLICATION OF MONO-SEX CULTURE SYSTEM, BECAUSE CATFISH MALES GROW FASTER THAN FEMALES BY ~ 60%. HOWEVER, IT HAS NOT BEEN POSSIBLE TO TAKE ADVANTAGE OF SUCH SEX DIMORPHISM BECAUSE OF THE LACK OF INFORMATION NEEDED TO DEVELOP THE SEX MANIPULATION TECHNOLOGIES. OUR OVERARCHING HYPOTHESIS IS THAT SEX-SPECIFIC EXPRESSION OF CERTAIN GENES WITHIN THE SEX DETERMINATION REGION ARE AFFECTED BY EPIGENETIC DNA MODIFICATIONS, WHICH IN TURN, DETERMINES CATFISH SEX. IN THIS PROJECT, WE WILL TEST THIS HYPOTHESIS BY ACHIEVING THE FOLLOWING SPECIFIC OBJECTIVES: 1) DETERMINE THE SEX-SPECIFIC EPIGENETIC MODIFICATIONS (METHYLATION) IN GENETIC MALES AND FEMALES DURING EARLY SEX DIFFERENTIATION; 2) DETERMINE THE INVOLVEMENT OF SUCH EPIGENETIC MODIFICATIONS IN REGULATION AND SEX-SPECIFIC EXPRESSION OF GENES WITHIN THE SEX DETERMINATION REGION; 3) DETERMINE THE INVOLVEMENT OF EPIGENETIC MODIFICATIONS IN TEMPERATURE-INDUCED SEX REVERSAL; AND 4) FUNCTIONAL ANALYSIS OF THE SEX DETERMINATION CANDIDATE GENE (BCAR1) IN CATFISH THROUGH KNOCKOUT AND GENOME EDITING. ACHIEVING THESE GOALS WILL ALLOW US TO LEARN ABOUT MOLECULAR MECHANISMS OF SEX DETERMINATION IN CATFISH, PROVIDING INFORMATION FOR SEX MANIPULATION IN CATFISH. SUCH INFORMATION WILL DESIGNING OF STRATEGIES TO DEVELOP MONOSEX TECHNOLOGIES FOR CATFISH AQUACULTURE. IN THE LONG TERM, THIS WORK WILL PROVIDE INFORMATION FOR MORE EFFICIENT PRODUCTION OF CATFISH, ENHANCING PRODUCTION AND PROFIT MARGINS FOR THE US CATFISH INDUSTRY. ?