Hepatopancreas and ovary transcriptome analyses reveal key physiological changes in the pubertal molt of mud crabs Scylla paramamosain.

Pubertal molt represents a critical biological process underlying successful copulation in Scylla paramamosain, during which female mud crabs engage in mating immediately following the completion of this molt. Pubertal molt is the sole route for subadult-to-adult transition for female crabs, leading to accelerated ovarian development. The present study performed transcriptomic profiling of the hepatopancreas and ovary of S. paramamosain across pubertal molt to thoroughly elucidate the key physiological modulations governing pubertal molt. Gene set enrichment analysis (GSEA) indicated gene sets associated with nucleotide, carbohydrate, amino acid, lipid, coenzyme/cofactor, and oxidation-reduction metabolism in hepatopancreas, and cell-cell adhesion via plasma membrane adhesion molecules in the ovary, were significantly enriched prior to molt, respectively. Conversely, gene sets related to ion transport and phagosome were notably increased in the hepatopancreas after molt. Totally 2193 and 604 differentially expressed genes (DEGs) were identified in hepatopancreas and ovary, respectively, when comparing pre- and post-molt conditions. GO and KEGG enrichment analysis of DEGs indicated processes including cellular localization, localization establishment, transport, chitin metabolism, glucosamine-containing compound and amino sugar metabolic processes, vacuole organization, oxidative phosphorylation, and phagosome pathways were notably induced. Meanwhile, oxidation-reduction process, coenzyme/cofactor binding, and metabolism of carbohydrate, nucleotide, and, amino acid were inhibited in hepatopancreas post-pubertal molt. Furthermore, a substantial number of genes involved in molt, hormone regulation, immunity, and metabolism in the hepatopancreas and ovary were significantly regulated, which revealed that molt was induced in the hepatopancreas but attenuated in the ovary, hormone regulation was suppressed in both hepatopancreas and ovary, and immune response was downregulated in hepatopancreas but upregulated in ovary after molt. Collectively, these findings may contribute to a comprehensive understanding of the regulatory mechanisms of the pubertal molt of female S. paramamosain.