Transcriptomic Mechanisms Underlying Dietary Fish Oil, Phospholipid, and Vitamin E Supplementation in Promoting Ovarian Development in Leptobotia elongata

Leptobotia elongata, a rare freshwater fish endemic to China, frequently exhibits retarded ovarian development under artificial captivity, severely constraining large-scale reproduction. This study evaluated the effects of combined dietary supplementation with fish oil (FO), soybean phospholipids (PLs), and vitamin E (VE) on ovarian development through a 6-month feeding trial. Hematoxylin and eosin staining revealed that oocytes in the mixed lipid group (MIX: FO + PL + VE) advanced to developmental stage III, whereas oocytes in the control group (CON) were predominantly arrested at stages I–II. Transcriptomic analysis identified 1393 differentially expressed genes (651 upregulated, 742 downregulated). Upregulated genes were enriched in nucleolus- and nuclear pore-related cellular components and RNA-binding molecular functions, indicating enhanced ribosome biogenesis capacity. Downregulated genes were concentrated in DNA damage repair pathways and Mediator complex-mediated transcriptional regulation, suggesting alleviation of oxidative stress. Protein–protein interaction network analysis identified mphosph10, utp11, nat10, emg1, and ftsj3 as core hub genes. Additionally, 44 differentially expressed transcription factors were identified, with Forkhead (forkhead.38), GATA (gata.4), and MYB (myb.40) significantly upregulated, indicating activation of a pro-developmental transcriptional program. These findings provide a theoretical basis for precision lipid nutrition formulation in L. elongata fish diets.