Division of Marine Environment & Bioscience, Korea Maritime University, Busan 606-791, Republic of Korea.
Comp Biochem Physiol B Biochem Mol Biol. 2012 Feb;161(2):124-33. doi: 10.1016/j.cbpb.2011.10.003. Epub 2011 Oct 19.
Gonadotropin-releasing hormones (GnRHs) play pivotal roles in the control of reproduction and gonadal maturation in teleost fish. Fish have multiple GnRH genes that encode structurally distinct peptides. We identified salmon GnRH (sGnRH), seabream GnRH (sbGnRH), and chicken GnRH-II (cGnRH-II) by cDNA cloning in cinnamon clownfish (Amphiprion melanopus) using reverse transcription-PCR (RT-PCR) and rapid amplification of cDNA ends-PCR (RACE-PCR). Gene identity was confirmed by sequence alignment and subsequent phylogenetic analyses. We also investigated GnRH mRNA expression in the gonads by quantitative real time-PCR (Q-PCR), and measured plasma estradiol-17β (E(2)) levels in immature fish following treatment with the three molecular forms of GnRHs. The expression levels of sGnRH, sbGnRH, and cGnRH-II mRNA were higher in mature testes and ovaries, as compared to the levels in gonads at earlier stages of maturity. The levels of the three prepro-GnRH mRNA species and the plasma E(2) levels increased after injection of the three GnRH variants. These findings support the hypothesis that GnRH peptides play important roles in the regulation of the hypothalamic-pituitary-gonadal axis and are probably involved in paracrine control of gonadal development and sex change in cinnamon clownfish.
促性腺激素释放激素（GnRHs）在鱼类的生殖和性腺成熟中起着关键作用。鱼类有多个 GnRH 基因，编码结构不同的肽。我们通过肉桂小丑鱼（Amphiprion melanopus）的逆转录 PCR（RT-PCR）和快速扩增 cDNA 末端-PCR（RACE-PCR），通过 cDNA 克隆鉴定了鲑鱼 GnRH（sGnRH）、真鲷 GnRH（sbGnRH）和鸡 GnRH-II（cGnRH-II）。通过序列比对和随后的系统发育分析确认了基因同一性。我们还通过定量实时 PCR（Q-PCR）研究了 GnRH mRNA 在性腺中的表达，并在未成熟鱼中测量了三种 GnRH 分子形式处理后血浆雌二醇-17β（E2）水平。与成熟过程中更早阶段的性腺相比，sGnRH、sbGnRH 和 cGnRH-II mRNA 的表达水平在成熟的睾丸和卵巢中更高。三种前 prosGnRH mRNA 种类和血浆 E2 水平在注射三种 GnRH 变体后增加。这些发现支持 GnRH 肽在调节下丘脑-垂体-性腺轴中发挥重要作用的假设，并且可能参与肉桂小丑鱼性腺发育和性别转变的旁分泌控制。
