Exploring the role of miR-430 in hybrid fish during embryonic development

miR-430, a microRNA expressed at the maternal-zygotic transition (MZT) stage, plays a vital role in maternal transcript clearance and suppression of primordial germ cell-specific genes. This study investigated the expression and regulation of miR-430 in goldfish (Carassius auratus var., ♀) × rare gudgeon (Gobiocypris rarus, ♂) [s-GFRG, survival] and rare gudgeon (♀) × goldfish (♂) [d-RGGF, death] embryos to explore the role of miR-430 in hybrid fish. Gene sequence comparisons demonstrated that three types of miR-430 in s-GFRG exhibited similarity to that of the female parent goldfish (GF) and displayed characteristic variation. Conversely, d-RGGF exhibited two miR-430 variants resembling those of GF and rare gudgeon (RG). In addition, real-time quantitative PCR and whole-mount in situ hybridization revealed that the expression trend of miR-430 was the same in hybrid progenies, and temporal expression was delayed compared to that in the parental embryos. However, miR-430 expression was significantly lower in d-RGGF than in GF and s-GFRG embryos. Similar to the development of d-RGGF embryos, miR-430-silenced s-GFRG embryos exhibited morphological abnormalities including spinal curvature and pericardial cavity enlargement. Overexpression of miR-430 in d-RGGF embryos effectively rescued somitogenesis and prolonged fry survival. Thus, an abnormal MZT resulting from disturbed miR-430 expression may contribute to hybrid embryo mortality.