Nguyen Anh Tuan, Chia Jolyn H Z, Kazeto Yukinori, Lokman P Mark
Department of Zoology, University of Otago, 340 Great King Street, PO Box 56, Dunedin 9054, New Zealand.
Department of Zoology, University of Otago, 340 Great King Street, PO Box 56, Dunedin 9054, New Zealand.
Gen Comp Endocrinol. 2019 Feb 1;272:83-92. doi: 10.1016/j.ygcen.2018.12.001. Epub 2018 Dec 6.
Despite tremendous importance of follicle-stimulating hormone (Fsh) and luteinizing hormone (Lh) as primary controllers of reproductive development, information on the expression profiles of the genes encoding gonadotropin subunits and gonadotropin receptors (Fshr and Lhr) in wild eels are essentially non-existent. This study investigated pituitary fshb and lhb mRNA levels and ovarian fshr and lhr mRNA levels of wild shortfinned eels, Anguilla australis at different stages of oogenesis. Protein expression of Fsh in the pituitary was also quantified and visualized using slot blot and immunohistochemistry. Pituitary fshb and lhb mRNA levels showed a differential expression pattern, fshb mRNA levels increasing significantly from the perinucleolus (PN) to the oil droplet stage (OD) before slightly decreasing (not significantly) in the early vitellogenic stage (EV). A similar trend was observed in relative Fsh protein levels analyzed by slot blot and immunohistochemistry, but this trend was not reflected in the plasma levels of sex steroids. In contrast, pituitary lhb mRNA levels increased significantly from the PN to EV stage. A higher expression of Fsh at both mRNA and protein levels in the pituitary of eels at the OD stage compared to other investigated stages suggests that synthesis of Fsh production in the pituitary may reach a peak at the OD stage. In the ovary, transcript abundances of fshr and lhr gradually increased during previtellogenic follicle growth, but markedly and significantly increased thereafter. Taken together, our data suggest i) that Fsh release may be very limited, or absent, prior to onset of puberty in shortfinned eels and ii) that Lh is not functionally important in this fish during the EV stage.
尽管促卵泡激素（Fsh）和促黄体生成素（Lh）作为生殖发育的主要调控因子具有极其重要的意义，但关于野生鳗鱼中促性腺激素亚基和促性腺激素受体（Fshr和Lhr）编码基因的表达谱信息基本不存在。本研究调查了野生短鳍鳗鲡（Anguilla australis）在不同卵子发生阶段垂体中fshb和lhb的mRNA水平以及卵巢中fshr和lhr的mRNA水平。还使用狭缝印迹和免疫组织化学对垂体中Fsh的蛋白表达进行了定量和可视化分析。垂体中fshb和lhb的mRNA水平呈现出差异表达模式，fshb的mRNA水平从核仁周（PN）期到油滴期（OD）显著增加，然后在早期卵黄生成期（EV）略有下降（不显著）。通过狭缝印迹和免疫组织化学分析的相对Fsh蛋白水平也观察到了类似趋势，但这种趋势未反映在性类固醇的血浆水平中。相比之下，垂体中lhb的mRNA水平从PN期到EV期显著增加。与其他研究阶段相比，OD期鳗鱼垂体中Fsh在mRNA和蛋白水平上的表达更高，这表明垂体中Fsh产生的合成可能在OD期达到峰值。在卵巢中，fshr和lhr的转录本丰度在卵黄生成前卵泡生长过程中逐渐增加，但此后显著且明显增加。综上所述，我们的数据表明：i）在短鳍鳗鲡青春期开始之前，Fsh的释放可能非常有限或不存在；ii）在EV期，Lh在这种鱼类中功能上并不重要。
