Comparative Analysis of Gonadal Transcriptome Profiles in Neptunea arthritica cumingii with Different Shell Colors

Neptunea arthritica cumingii is an economically important large marine gastropod in northern China; however, overfishing has drastically reduced its commercial resource. Here, we investigated fecundity variations and gonadal gene expression profiles in female N. arthritica cumingii with three distinct shell colors: reddish-brown (HZ), yellowish-brown (HH), and white (BS). Significant fecundity variations were recorded across groups, with BS exhibiting remarkably higher fecundity than other groups. Transcriptomics revealed significant gene expression differences in gonads across groups (a total of 9 RNA-seq samples with 3 replicates for each group); 11,702, 14,731, and 15,706 differentially expressed genes (DEGs) were identified in HZ vs. BS, HH vs. BS, and HZ vs. HH groups, respectively. GO and KEGG enrichment analyses indicated that DEGs were involved in different biological processes. Notably, a DEG subset was significantly enriched for reproduction- and development-related pathways, including estrogen signaling, ovarian steroidogenesis, and oocyte meiosis. Candidate genes associated with fecundity were identified, including Vtg, Foxl2, 17β-HSDs, SOX9, and Dmrt1. Associated gene expression levels were significantly up-regulated in the BS group, suggesting these genes are potentially associated with female gonadal development and oogenesis processes. Furthermore, gene expression patterns were validated by qRT-PCR. The study provides a basis for future studies of fecundity-related traits in N. arthritica cumingii.