Transcriptomic profiling of oocyte maturation in allotetraploid hybrid fish and identification of HSD17b12 mediating DHP synthesis

Abstract

To reveal the molecular regulatory mechanism underlying oocyte development and maturation in an allotetraploid hybrid of Pengze crucian carp (♀) × Xingguo red carp (♂), the oocyte growth stage (PG, PV, EV, MV, LV and FG) and maturation stage (FG, S1, S2 and S3) were classified based on morphological characteristics and germinal vesicle dynamics. Transcriptomic analysis identified stage-specific differentially expressed genes (DEGs), among which DEGs from C. auratus subgenome exhibited a dosage advantage in core regulation. KEGG analysis of DEGs screened via trend analysis revealed that DEGs from C. carpio subgenome were enriched in fatty acid metabolism and oocyte meiosis, while DEGs from C. auratus subgenome were enriched in the thyroid hormone and ErbB signaling pathways. Furthermore, 17β-Hydroxysteroid dehydrogenase type 12 (HSD17b12), the core gene mediating 17α,20β-dihydroxy-4-pregnen-3-one (DHP) synthesis, was identified in the allotetraploid hybrid, whose expression pattern was consistent with the dynamic changes in serum DHP levels and functional validation in HEK293T cells further confirmed its DHP-producing capacity. This study clarifies the subgenomic functional divergence during ovulation and identifies HSD17b12 as the core gene for DHP synthesis in allotetraploid hybrids, providing a theoretical basis for reproductive regulation and genetic breeding of polyploid fish.

Keywords: Allotetraploid hybrid; HSD17b12; Oocyte; Subgenomes; Transcriptome.