HOW TO MAKE FEMALES OUT OF MALES; THE EFFECT OF INHIBITION AND STIMULATION OF P450-AROMATASE ON THE SEX DIFFERENTIATION OF ATLANTIC HALIBUT HIPPOGLOSSUS HIPPOGLOSSUS

摘要

The females of the commercial important species Atlantic halibut, Hippoglossus hippoglossus, grow faster and has a larger ultimate size than the males due to their delayed sexual maturation. Therefore, all-female production would be economically advantageous in the aquaculture industry. Mono-sex populations can be achieved by genetic manipulation (producing triploids) or hormone treatment (Benfey et al 2000), but these techniques are unacceptable in Norwegian aquaculture. Therefore our strategy is based on a naturally occurring event, namely sex alteration influenced by temperature (Devlin and Nagahama 2002). Gonadal development in lower vertebrates is mainly controlled by the enzyme P450-aromatase, which transforms testosterone into estrogen (Simpson et al 1994). This process seems to be temperature-sensitive (Baroiller et al 1999), which opens the possibility for sex reversing Atlantic halibut for aquaculture purpouses. Here we report on the identification of the Atlantic halibut orthologues of P450aromA and P450aromB, their tissue-specific expression, and their expression patterns during the period of embryonic differentiation. These results allow further investigation and understanding of the molecular basis of the sex differentiation in Atlantic halibut.