Kwon J Y, McAndrew B J, Penman D J
Institute of Aquaculture, University of Stirling, Stirling, FK9 4LA, Scotland, United Kingdom.
Mol Reprod Dev. 2001 Aug;59(4):359-70. doi: 10.1002/mrd.1042.
A brain aromatase gene was identified from the Nile tilapia Oreochromis niloticus. The cDNA sequence of this gene differed from that of the ovarian aromatase gene previously reported from this species. Tissue specific expression for both brain and ovarian aromatase genes was examined in the tissues of adult tilapia. Brain aromatase mRNA was expressed in the brain, kidney, eye, ovary, and testis, but not in the liver and spleen. Ovarian aromatase mRNA was expressed in the brain, spleen, ovary, and testis but not in the eye, kidney, and liver. Differential aromatase gene expression between the sexes was investigated in all-male (XY) and all-female (XX) groups of tilapia fry from fertilisation throughout the sexual differentiation period. Semi-quantitative RT-PCR analysis revealed that the initiation of expression of both aromatase genes lay between 3 and 4 dpf (days post fertilisation) in both sexes. The level of brain aromatase mRNA gradually increased throughout the period studied with little difference between the sexes. This contrasted with marked sexual dimorphism of ovarian aromatase mRNA expression. In females, the expression level was maintained or increased gradually throughout ontogeny, while the level in males was dramatically down-regulated between 15 and 27 dpf. Subsequently, the level of ovarian aromatase mRNA expression fluctuated slightly in both sexes, with the expression in females always being higher than in males. These findings clearly suggest that ovarian aromatase plays a decisive role in sexual differentiation in this species and that this is achieved by down-regulation of the expression of this gene in males. Mol. Reprod. Dev. 59: 359-370, 2001.
从尼罗罗非鱼（Oreochromis niloticus）中鉴定出一个脑芳香化酶基因。该基因的cDNA序列与先前报道的该物种卵巢芳香化酶基因的序列不同。在成年罗非鱼的组织中检测了脑和卵巢芳香化酶基因的组织特异性表达。脑芳香化酶mRNA在脑、肾、眼、卵巢和睾丸中表达，但在肝脏和脾脏中不表达。卵巢芳香化酶mRNA在脑、脾脏、卵巢和睾丸中表达，但在眼、肾和肝脏中不表达。在尼罗罗非鱼幼鱼从受精到整个性别分化期的全雄（XY）和全雌（XX）组中研究了两性之间芳香化酶基因的差异表达。半定量RT-PCR分析显示，两性中两种芳香化酶基因的表达起始均在受精后3至4天。在所研究的整个时期内，脑芳香化酶mRNA水平逐渐升高，两性之间差异不大。这与卵巢芳香化酶mRNA表达的明显性别二态性形成对比。在雌性中，表达水平在整个个体发育过程中保持或逐渐升高，而在雄性中，该水平在15至27 dpf之间急剧下调。随后，卵巢芳香化酶mRNA表达水平在两性中均略有波动，雌性中的表达始终高于雄性。这些发现清楚地表明，卵巢芳香化酶在该物种的性别分化中起决定性作用，并且这是通过下调该基因在雄性中的表达来实现的。《分子生殖与发育》59: 359 - 370, 2001年。
