Blázquez Mercedes, González Alicia, Papadaki Maria, Mylonas Constantinos, Piferrer Francesc
Institut de Ciències del Mar, Consejo Superior de Investigaciones Científicas, Passeig Marítim, 37-49, 08003 Barcelona, Spain.
Gen Comp Endocrinol. 2008 Aug;158(1):95-101. doi: 10.1016/j.ygcen.2008.06.001. Epub 2008 Jun 8.
The present study addresses the role of aromatase and estrogen receptors in sex differentiation and development. With this purpose, a sea bass female- and a male-dominant group were obtained by successive size gradings since in this species females are already larger than males at the time of sex differentiation. Changes in cyp19a and cyp19b gene expression and enzymatic activity were monitored by a validated real-time PCR and a tritiated water assay, respectively, during early development and sex differentiation. Changes in mRNA expression of estrogen receptors, both erb1 and erb2, were also assessed during this period. Results show clear sex-related differences in cyp19a gene expression and enzymatic activity in gonads, with females exhibiting significantly higher levels than males at 150 days post hatching (DPH), when histological signs of sex differentiation were evident. cyp19b gene expression and activity in brain were detectable during early ontogenesis at 50 DPH but no clear sex-related differences were observed. Both erb1 and erb2 showed higher gene expression levels in testis than in ovaries around 200-250 DPH, corresponding with the time of testicular differentiation and precocious male maturation, but no sex-related differences were found in the brain. Together these results indicate that in the European sea bass high expression levels of cyp19a are associated with ovarian differentiation and thus cyp19a can be considered as a suitable molecular marker of ovarian differentiation. However, the involvement of cyp19b in sex differentiation cannot be concluded. In addition, the higher levels of erb1 and erb2 in males versus females during sex differentiation, coinciding with precocious male maturation in the sea bass, suggest an important role for these receptors in testicular development and maturation.
本研究探讨了芳香化酶和雌激素受体在性别分化与发育中的作用。为此，通过连续的大小分级获得了海鲈雌性和雄性优势群体，因为在这个物种中，雌性在性别分化时就已经比雄性大。在早期发育和性别分化过程中，分别通过经过验证的实时PCR和氚水测定法监测cyp19a和cyp19b基因表达及酶活性的变化。在此期间，还评估了雌激素受体erb1和erb2的mRNA表达变化。结果显示，性腺中cyp19a基因表达和酶活性存在明显的性别相关差异，在孵化后150天（DPH）时，雌性的水平显著高于雄性，此时性别分化的组织学迹象明显。在50 DPH的早期个体发育过程中可检测到脑内cyp19b基因表达和活性，但未观察到明显的性别相关差异。在200 - 250 DPH左右，erb1和erb2在睾丸中的基因表达水平均高于卵巢，这与睾丸分化和早熟雄性成熟的时间相对应，但在脑中未发现性别相关差异。这些结果共同表明，在欧洲海鲈中，cyp19a的高表达水平与卵巢分化相关，因此cyp19a可被视为卵巢分化的合适分子标记。然而，无法得出cyp19b参与性别分化的结论。此外，在性别分化期间，雄性中erb1和erb2的水平高于雌性，这与海鲈的早熟雄性成熟相一致，表明这些受体在睾丸发育和成熟中起重要作用。
