** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** OUR LONG-TERM GOAL IS TO IMPROVE PRODUCTION TRAITS OF FARMED CATFISH THROUGH TRANSGENESIS AND TO ACCOMPLISH REVERSIBLE GENETIC STERILITY IN FISH, SPECIFICALLY CATFISH, TO ACCOMPLISH ABSOLUTE REPRODUCTIVE CONFINEMENT, PREVENTING ESTABLISHMENT OF TRANSGENIC GENOTYPES IN THE NATURAL ENVIRONMENT. SUCH A TECHNOLOGY COULD BE USED IN A VARIETY OF FISH INCLUDING ANY DOMESTIC GENOTYPE, INTERSPECIFIC HYBRID, TRANSGENIC OR EXOTIC, TO MINIMIZE IMPACTS ON THE NATURAL ENVIRONMENT, PROTECT GENETIC BIODIVERSITY AND ECOSYSTEMS, INCREASING ENVIRONMENTAL FRIENDLINESS OF AQUACULTURE AND TRANSGENIC FISH. THE SUCCESSFUL CULMINATION OF THE PROJECT WOULD RESULT IN A SYSTEM THAT WOULD PREVENT ANY GENE FLOW OF TRANSGENES OR DOMESTIC GENES INTO WILD POPULATIONS.WE HAVE PRODUCED TRANSGENIC FISH POSSESSING MULTIPLE INSERTIONS OF TRANSGENESWHILE MUTATING OTHER GENES. ONE STRATEGY INCLUDES THE MUTATION OF ONE REPRODUCTIVE GENE OR A SECOND SUCH GENE TO REDUNDANTLY GUARANTEE STERILITY. THESE FISH HAVE IMPROVED GROWTH, DISEASE RESISTANCE, AND N-3 FATTY ACID LEVELS. THE INFERTILITY WAS REVERSED WITH HORMONE THERAPY FOR THE FISH WITH ONE MUTATED REPRODUCTIVE GENE. HOWEVER, THE SUCCESS HAS BEEN VARIABLE AND RELATIVELY LOW, AND THE SPAWNING RATE NEEDS TO BE IMPROVED TO PROVE EFFICACY TO GOVERNMENT REGULATORY AGENCIES AND FOR ECONOMICAL COMMERCIALIZATION. TWO REPRODUCTIVE GENE KNOCKOUTS HAVE NOT BEEN EVALUATED FOR FERTILITY RESTORATION. THUS, THE MAIN THRUST OF THIS PROPOSAL IS OPTIMIZATION OF HORMONE THERAPY AND TO DETERMINE IF THE REDUNDANT SYSTEM REQUIRES THE SAME OR DIFFERENT HORMONE DOSAGE REGIMEN TO RESTORE FERTILITY AS THE EDITING OF A SINGLE REPRODUCTIVE GENE.