Comparative Transcriptomic Analysis of Prefertilization Stage V Testes and Ovaries in Hemibagrus guttatus

Abstract

To investigate the gene expression characteristics associated with stage V gonadal development in Hemibagrus guttatus, transcriptome sequencing was performed on stage V testes and ovaries using an Illumina high-throughput sequencing platform. In total, 97,689 unigenes were obtained after de novo assembly; a total of 5364 differentially expressed genes (DEGs) were identified between testes and ovaries samples. Compared with the testes, 2518 genes (46.9%) were upregulated and 2846 genes (53.1%) were downregulated in the ovaries. Combined with Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses, 80 key DEGs related to gonadal development were further screened out, among which 44 were highly expressed in testes and 36 were highly expressed in ovaries. These DEGs were mainly enriched in 21 signaling pathways regulating sex determination, differentiation, and gonadal development, including steroid hormone biosynthesis, gonadotropin regulation, the TGF-β pathway, and progesterone-mediated oocyte maturation. These results indicate that multiple genes involved in hormone synthesis, gamete maturation, and energy and substance metabolism exhibit significant sex-biased expression in stage V testes and ovaries of H. guttatus, which may collectively provide the endocrine environment and the material and energy reserves required for subsequent fertilization.