earticle

영어

Sex determination in some reptiles, amphibians, and fishes is known to be influenced greatly by environmental factors. Aromatase is the key enzyme in estrogen production and therefore is a reliable marker of female differentiation. Aromatase cytochrome P450 (P450arom) is the enzyme complex responsible for conversion of androgens to estrogens in vertebrates. Consequently, in some fishes its activity appears critical to ovarian differentiation. Olive flounder (Paralichthys olivaceus) is a commercially important flatfish in which females grow larger than males and sex determination is temperature sensitive. Through cloning of the P450arom gene in ovary and quantitative reverse transcription-polymerase chain reaction, we developed a biomarker for early female differentiation in olive flounder. The deduced amino acid sequence for olive flounder P450arom is similar to other teleosts. The part of a gonad was subjected to sex discrimination experiment using aromatase marker, and the rest part, by histological observation. The result of sex discrimination by using markers developed in this study was absolutely correspondent to the result acquired from histological observation, confirming its high accuracy as an useful marker. Gonadal histology confirmed predictions of sex based on P450arom expression in juvenile flounder, demonstrating that the patterns of P450arom expression observed relate to sex-specific differentiation. Also, in order to apply the method, developed in this study, juvenile (fry) flounder from fish farm were examined, and it revealed that sex discrimination of flounders under early sex differentiation is successful. This research represents a unique approach to assessing sex differentiation in a natural population, and a powerful technique for better understanding mechanisms of flounder sex determination and rapidly defining conditions for controlling sex for aquaculture assessing sex responses using the aromatase marker.