Sex differences in aromatase gene expression in the XXXX brain.

@entity72812 @entity4998 @entity7021 @entity2931
The brain of teleost fish exhibits a significant degree of sexual plasticity, even in adulthood. This unique feature is almost certainly attributable to a teleost-specific @entity4998 , which remains largely unknown. To dissect the molecular basis of @entity4998 , we searched for genes differentially expressed between both sexes in the @entity7021 brain. One gene identified in the screen, @entity72812 , which encodes the steroidogenic enzyme aromatase, was selected for further analysis. As opposed to the situation in most vertebrates, @entity7021 @entity72812 is expressed at higher levels in the adult female brain than the male brain. The female-biased expression in the brain is consistent regardless of reproductive or diurnal cycle. @entity7021 @entity72812 is expressed throughout the ventricular zones in wide areas of the brain, where, in most regions, females have a greater degree of expression compared to males, with the optic tectum exhibiting the most conspicuous predominance in females. Contrary to what is known in mammals, @entity72812 expression exhibits neither a transient elevation nor a sex difference in @entity7021 embryos. It is not until just before the onset of puberty that @entity72812 expression in the @entity7021 brain is sexually differentiated. Finally, @entity72812 expression in the @entity7021 brain is not under the direct control of sex chromosome genes but relies mostly, if not solely, on @entity2931 derived from the gonad. These unique properties of aromatase expression in the brain probably contribute substantially to the less rigid sexual differentiation process, thus ensuring remarkable sexual plasticity in the teleost brain.
