Establishment of procedures for studying mPR-interacting agents and physiological roles of mPR

To obtain decisive evidence for the roles of mPRs, we are establishing strains of medaka fish that are deficient in mPRs. In medaka, four subtypes of mPR genes (α, β, γ, and α2) have been identified. By reverse genetic screening, we have selected three to four strains in which a point mutation has been induced in the coding sequence of the mPR subtypes. However, homozygous mutants of each mPR gene showed no phenotype. The results suggested that mPR genes share redundancy. We are currently producing double and triple mutants of the mPR subtypes. The physiological roles of mPRs will be demonstrated using the mutant medaka strains.