Duangkaew Rungsun, Jangprai Araya, Ichida Kensuke, Yoshizaki Goro, Boonanuntanasarn Surintorn
School of Animal Production Technology, Institute of Agricultural Technology, Suranaree University of Technology, 111 University Avenue, Muang, Nakhon Ratchasima, 30000, Thailand.
Department of Marine Biosciences, Tokyo University of Marine Science and Technology, Minato-Ku, Tokyo, 108-8477, Japan.
Theriogenology. 2019 Jun;131:61-71. doi: 10.1016/j.theriogenology.2019.01.022. Epub 2019 Mar 15.
The analysis of early gonadogenesis during larval development requires a molecular marker that is specifically expressed in the germ cell lineage, such as the vasa gene. In this study, we cloned and characterized vasa in the striped catfish (Pangasianodon hypophthalmus), and designated this as Phy-vasa. Phy-vasa contained all of the predicted consensus motifs that are shared among the vasa genes in other fish species, including RG and RGG repeats, ATPase motifs, and a DEAD-box, and phylogenetic analysis using various DEAD-box family proteins demonstrated that the Phy-vasa protein clustered within the Vasa family. Reverse transcription polymerase chain reaction (RT-PCR) indicated that Phy-vasa mRNA only occurred in the testis and ovary, and in situ hybridization showed that the gene was expressed only in the germ cells, with strong expression in the spermatogonia and oogonia. To investigate early gonadogenesis in catfish larvae, we undertook histological characterization and in situ hybridization using a Phy-vasa probe, which showed that migration of the primordial germ cells (PGCs) most commonly occurred in larvae at 2-10 days post-fertilization (dpf), the PGCs started to be surrounded by gonadal somatic cells at around 10-20 dpf, and rapid proliferation of the PGCs had begun by 30 dpf. These findings provide a valuable insight into early gonadal development in the striped catfish.
对幼体发育过程中早期性腺发生的分析需要一种在生殖细胞谱系中特异性表达的分子标记，比如瓦萨基因（vasa gene）。在本研究中，我们克隆并鉴定了条纹鲶鱼（Pangasianodon hypophthalmus）中的瓦萨基因，并将其命名为Phy-vasa。Phy-vasa包含了其他鱼类物种中瓦萨基因共有的所有预测共有基序，包括RG和RGG重复序列、ATP酶基序以及一个DEAD框，使用各种DEAD框家族蛋白进行的系统发育分析表明，Phy-vasa蛋白聚集在瓦萨家族内。逆转录聚合酶链反应（RT-PCR）表明，Phy-vasa mRNA仅在睾丸和卵巢中出现，原位杂交显示该基因仅在生殖细胞中表达，在精原细胞和卵原细胞中表达强烈。为了研究鲶鱼幼体的早期性腺发生，我们使用Phy-vasa探针进行了组织学特征分析和原位杂交，结果表明，原始生殖细胞（PGCs）的迁移最常发生在受精后2-10天（dpf）的幼体中，PGCs在10-20 dpf左右开始被性腺体细胞包围，到30 dpf时PGCs已开始快速增殖。这些发现为条纹鲶鱼的早期性腺发育提供了有价值的见解。
