Triploid rainbow trout (Oncorhynchus mykiss) raised increasing concern on the commercial farming due to its prominent advantages, such as improved growth performance and efficiency of feed utilization. It typically shows impaired ovary development and is relatively sterile. Spindlin-1 (Spin-1) plays vital roles in hormone regulation, gametogenesis, and oocyte meiotic resumption in almost all vertebrates. miRNAs, small non-coding RNAs, have emerged as major regulators of gene expression in vertebrates by modulating target genes. In the present study, eight adult females of diploid and triploid rainbow trout maintained in the same conditions were included. miR-1388-5p was predicted to target the annotated 3′-UTR of Spin-1 specifically by online miRNA target prediction database: “MicroTrout”. Spin-1 mRNA was downregulated, and in contrast, miR-1388-5p was significantly elevated in the ovary of triploid rainbow trout by quantitative PCR (P < 0.01). Pearson's correlation indicated that the expression of Spin-1 was inversely correlated with that of miR-1388-5p both in diploid and triploid females. Then, Spin-1 was validated to be directly targeted and downregulated by miR-1388-5p by luciferase assay (P < 0.01). E₂ injection elevated Spin-1 while suppressed miR-1388-5p expression, while the concentration of estradiol in diploid serum is relatively higher than that in triploid serum by ELISA (P < 0.05). The results showed that estrogen regulation can stimulate the expression of Spin-1 by inhibiting the expression of miR-1388-5p. The present evidence provide new insight into the mechanism underlying the impaired ovary development of triploid fish from a new perspective.

三倍体虹鳟鱼（Oncorhynchus mykiss）由于其显着的优势（例如改善的生长性能和饲料利用效率）而引起了商业养殖的关注。它通常显示卵巢发育受损并且相对不育。Spindlin-1（Spin -1）在几乎所有脊椎动物中的激素调节，配子发生和卵母细胞减数分裂恢复中都起着至关重要的作用。通过调节靶基因，miRNA（小型非编码RNA）已成为脊椎动物基因表达的主要调节剂。在本研究中，包括八只成年雌性二倍体和三倍体虹鳟维持在相同条件下。预计miR-1388-5p靶向自旋的注释3'-UTR-1具体由在线miRNA目标预测数据库：“ MicroTrout”提供。Spin -1 mRNA的表达下调，相反，通过定量PCR，miR-1388-5p在三倍体虹鳟的卵巢中显着升高（P <0.01）。皮尔森相关性表明，在二倍体和三倍体雌性动物中，Spin -1的表达与miR-1388-5p的表达呈负相关。然后，通过萤光素酶测定法验证了Spin -1被miR-1388-5p直接靶向并下调（P <0.01）。E ₂注射升高自旋-1抑制miR-1388-5p表达，而二倍体血清中的雌二醇浓度相对高于三倍体血清中的雌二醇浓度（P <0.05）。结果表明，雌激素调节可以通过抑制miR-1388-5p的表达来刺激Spin -1的表达。本证据从新的角度为三倍体鱼类卵巢发育受损的潜在机制提供了新的见解。