Transcriptome analysis of the ovary and testis of the pearl oyster Pinctada fucata: Identification of genes and pathways involved in gonadal development.

Pinctada fucata is a commercially vital species in global pearl aquaculture, producing high-quality pearls. To investigate the molecular regulatory mechanisms of gonadal development in P. fucata, transcriptome analysis was employed to compare expression profiles between testis and ovary across four key developmental stages. A total of 56.86 Gb of clean data was generated, including 392,510 circular consensus sequencing reads, among which 292,295 full-length non-chimeric (FLNC) sequences were identified. A transcript clustering analysis of FLNC reads revealed 89,645 high-quality consensus sequences. 17,646 gene loci were identified, including 8588 novel loci and 28,121 newly discovered transcripts, of which 17,350 were successfully annotated. The boundaries of 12,040 genes on the chromosomes were corrected, and 10,761 complete open reading frame sequences. 281 genes related to gonadal development were identified, including 186 genes with full-length cDNAs in the PacBio library. The study found that HUS1-like, MAD2A-X1, and BLM were stage-specifically upregulated during ovarian maturation, ensuring the accuracy of meiosis. Meanwhile, NR0B1, ETV7L-X5, and CAPRIN1-X2 promoted testicular maturation by regulating somatic cell differentiation and the germ cell microenvironment. KEGG enrichment analysis identified key pathways involved in gonadal development, including the ribosome, oxidative phosphorylation, DNA replication, and lysosome. Fatty acid metabolism was linked to ovarian maturation, while the FoxO and ErbB signaling pathways were associated with testicular maturation. These findings offer valuable insights into the molecular mechanisms regulating gonadal development in P. fucata and enhance genomic resources for this economically important species.