The availability of sexually mature fish often dictates the success of its captive breeding. In this study, we induced reproductive development in juvenile protogynous tiger grouper through oral administration of a plasmid (p) containing an engineered follicle-stimulating hormone (FSH). An expression construct (pcDNA3.1) was designed to express a single-chain FSH consisting of giant grouper FSH β-subunit and glycoprotein subunit-α (CGα), linked by the carboxy-terminal peptide (CTP) sequence from the human chorionic gonadotropin (hCG). Single oral delivery of pFSH encapsulated in liposome and chitosan to tiger grouper yielded a significant increase in plasma FSH protein level after 4 days. Weekly pFSH feeding of juvenile tiger groupers for 8 weeks stimulated ovarian development as indicated by a significant increase in oocyte diameter and progression of oocytes to cortical alveolar stage. As the pFSH treatment progressed from 20 to 38 weeks, female to male sex change was initiated, characterized by oocyte regression, proliferation of spermatogonial cells, and occurrence of spermatogenic cysts. It was also associated with significantly lower mRNA expression of steroidogenic genes (cyp11b, cyp19a1a, and foxl2) and basal plasma levels of sex steroid hormones 17β-estradiol (E₂), testosterone (T), and 11-ketotestosterone (11KT). Results suggest that pFSH stimulates ovarian development up to cortical alveolar stage and then initiates sex change in tiger grouper. These findings significantly contribute to our knowledge on the role of FSH in the development of protogynous hermaphroditic fish. This study is the first to demonstrate induction of reproductive development in fish through oral delivery of plasmid gonadotropin.

中文翻译：

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口服递送的FSH DNA诱导雌性石斑鱼的性腺发育。

有性成熟鱼的可用性通常决定了圈养繁殖的成功。在这项研究中，我们通过口服施用含有工程促卵泡激素（FSH）的质粒（p）来诱导幼年虎原石斑鱼的生殖发育。设计一种表达构建体（pcDNA3.1）以表达由巨石斑鱼FSHβ亚基和糖蛋白亚基α（CGα）组成的单链FSH，该单链FSH通过人绒毛膜促性腺激素的羧基末端肽（CTP）序列连接（hCG）。4天后，将脂质体和壳聚糖封装的pFSH单次口服递送至老虎石斑鱼，血浆FSH蛋白水平显着增加。每周用pFSH喂食小老虎石斑鱼达8周，可刺激卵巢发育，这是卵母细胞直径显着增加和卵母细胞发展到皮质肺泡阶段所表明的。随着pFSH治疗从20周发展到38周，开始由女性向男性的性别转变，其特征是卵母细胞退化，精原细胞的增殖和生精囊肿的发生。它还与类固醇生成基因的mRNA表达显着降低有关（cyp11b，cyp19a1a和foxl2）以及性类固醇激素17β-雌二醇（E ₂），睾丸激素（T）和11-酮睾丸激素（11KT）的基础血浆水平。结果表明，pFSH刺激卵巢发育直至皮质肺泡阶段，然后引发老虎石斑鱼的性别变化。这些发现大大有助于我们了解FSH在雌性雌雄同体鱼类发育中的作用。这项研究是第一个通过口服递送促性腺激素来证明鱼类生殖发育的方法。