Candelma Michela, Valle Luisa Dalla, Colella Sabrina, Santojanni Alberto, Carnevali Oliana
Laboratory of Developmental and Reproductive Biology, DiSVA, Università Politecnica delle Marche, Ancona, Italy.
Department of Biology, University of Padua, 35131, Padua, Italy.
Fish Physiol Biochem. 2018 Jun;44(3):895-910. doi: 10.1007/s10695-018-0479-z. Epub 2018 Feb 23.
Teleosts have many spawning strategies and the hormonal control of gametogenesis is not well defined among the species or even, between sexes. To increase the knowledge of gonadotropin hormones, we studied the trend by gene expression of gonadotropin receptors in the follicles and testis at different maturity stages in the European hake (Merluccius merluccius), a multiple-spawning species. With this aim, fshr and lhr were sequenced, characterized, and their gene expression was quantified in oocytes and in testes at different maturity stages. The deduced amino acid sequences were used to phylogenetic studies and evidenced that both receptors are phylogenetically closed to other gadoid species. The gene expression of both receptors was poorly expressed in primary follicles, increased in vitellogenic follicles and to later decrease in hydrated oocytes. In testis, highest levels of lhr were detected during spermiation, while levels of fshr were constant. For the first time, a histological analysis was performed in European hake testes showing an unrestricted lobular testis. To better elucidate the mechanisms involved in the oogenesis of the European hake, the expression of estrogen receptor and cyp19a was also investigated displaying high levels in all classes of follicles. All these data allow to increase the knowledge on reproductive physiology of an important socioeconomical species and it seeks to shed more light on the role of the receptors here studied during gametogenesis of multiple-spawning fish.
硬骨鱼有多种产卵策略，而且在不同物种间甚至两性之间，配子发生的激素控制都尚未明确。为了增加对促性腺激素的了解，我们研究了欧洲无须鳕（Merluccius merluccius）这一多次产卵物种在不同成熟阶段卵泡和睾丸中促性腺激素受体的基因表达趋势。为此，对促卵泡激素受体（fshr）和促黄体激素受体（lhr）进行了测序、表征，并对不同成熟阶段的卵母细胞和睾丸中的基因表达进行了定量分析。推导的氨基酸序列用于系统发育研究，结果表明这两种受体在系统发育上与其他鳕形目物种相近。这两种受体的基因表达在初级卵泡中表达较低，在卵黄生成卵泡中增加，随后在水化卵母细胞中下降。在睾丸中，促黄体激素受体（lhr）在精子形成过程中检测到最高水平，而促卵泡激素受体（fshr）的水平则保持恒定。首次对欧洲无须鳕睾丸进行了组织学分析，结果显示为无限制小叶睾丸。为了更好地阐明欧洲无须鳕卵子发生所涉及的机制，还研究了雌激素受体和cyp19a的表达，结果显示在所有类型的卵泡中表达水平都很高。所有这些数据有助于增加对一种重要社会经济物种生殖生理学的了解，并试图进一步阐明这里所研究的受体在多次产卵鱼类配子发生过程中的作用。
