Fu Yuanshuai, Xu Zhe, Wen Bin, Gao Jianzhong, Chen Zaizhong
Key Laboratory of Freshwater Aquatic Genetic Resources, Ministry of Agriculture, Shanghai Ocean University, Shanghai, China.
Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai, China.
Front Physiol. 2020 Aug 11;11:754. doi: 10.3389/fphys.2020.00754. eCollection 2020.
The discus fish () is an ornamental fish that is well-known around the world. In artificial reproduction, they must be matched by one male and one female, whereas phenotype investigation indicated that there are no significant differences in appearance between males and females, which causes great difficulties in the mating during artificial reproduction. So, it is of great importance to establish artificial sex identification methods for the discus fish. The molecular mechanism of the sexual dimorphism of the discus fish was previously unknown. In this study, we constructed six cDNA libraries from three adult testes and three adult ovaries and performed RNA sequencing for identifying sex-biased candidate genes and microRNAs (miRNAs). A total of 50,082 non-redundant genes (unigenes) were identified, of which 18,570 unigenes were significantly overexpressed in testes, and 11,182 unigenes were significantly overexpressed in ovaries. A total of 551 miRNAs were identified, of which 47 miRNAs were differentially expressed between testes and ovaries. Eight differentially expressed unigenes, seven differentially expressed miRNAs and one non-differential miRNA were validated by quantitative real-time polymerase chain reaction. Twenty-four of these differentially expressed miRNAs and their 15 predicted target genes constituted 41 miRNA-mRNA interaction pairs, and some of vital sex-related metabolic pathways were also identified. These results revealed these differentially expressed genes and miRNAs between ovary and testis might be involved in regulating gonadal development, sex determination, gametogenesis, and physiological function maintenance, and there are complex regulatory networks between genes and miRNAs. It can help us understand the molecular mechanism of the sexual dimorphism and obtain a high-efficiency sex identification method in the artificial reproduction process of the discus fish.
七彩神仙鱼是一种在全球都很知名的观赏鱼。在人工繁殖中，它们必须一雄一雌配对，然而表型研究表明，雌雄在外观上没有显著差异，这给人工繁殖过程中的配对带来了很大困难。因此，建立七彩神仙鱼的人工性别鉴定方法非常重要。此前，七彩神仙鱼性别二态性的分子机制尚不清楚。在本研究中，我们构建了三个成年睾丸和三个成年卵巢的六个cDNA文库，并进行了RNA测序，以鉴定性别偏向性候选基因和微小RNA（miRNA）。共鉴定出50,082个非冗余基因（单基因），其中18,570个单基因在睾丸中显著高表达，11,182个单基因在卵巢中显著高表达。共鉴定出551个miRNA，其中47个miRNA在睾丸和卵巢之间差异表达。通过定量实时聚合酶链反应验证了8个差异表达的单基因、7个差异表达的miRNA和1个非差异表达的miRNA。这些差异表达的miRNA中有24个及其15个预测的靶基因构成了41个miRNA- mRNA相互作用对，还鉴定出了一些重要的与性别相关的代谢途径。这些结果表明，卵巢和睾丸之间这些差异表达的基因和miRNA可能参与调节性腺发育、性别决定、配子发生和生理功能维持，并且基因和miRNA之间存在复杂的调控网络。这有助于我们了解性别二态性的分子机制，并在七彩神仙鱼的人工繁殖过程中获得高效的性别鉴定方法。
