The circular RNA expression landscape across tissues implicates their functional roles in the marine gastropod Rapana venosa

Abstract The carnivorous marine gastropod, Rapana venosa, also known as the veined rapa whelk, has recently gained considerable attention due to its dual significance as both a valuable commercial seafood resource and a biological invader with widespread ecological implications. Significant efforts have been made to investigate the molecular pathways governing the specific adaptations in R. venosa. However, the regulatory mechanisms of these pathways remain largely unclear. Circular RNA (circRNA), a newly-recognized class of non-coding molecules, plays crucial roles in post-transcriptional regulation, impacting various fundamental bioprocesses including development, cell proliferation, immunity, and disease pathogenesis. In this study, we conducted a comprehensive genome-wide profiling of circRNAs across eleven tissues of R. venosa. We identified a total of 1,214 circRNA genes across tissues, with 640 regarded as high-confidence candidates. CircRNAs displayed overall low expression levels, diverse isoform types, and dynamic expression patterns across various tissues. Our comparative analyses revealed a few circRNA genes with a great diversity of isoforms and abundant expression in the salivary gland, suggesting potential roles in the feeding process of R. venosa. Furthermore, Gene Ontology enrichment analysis indicated the potential involvement of commonly expressed circRNAs in fundamental cellular processes, including cell division, amide biosynthesis, and cellular response to hormone stimuli. Our study represents the initial in-depth examination of circRNAs across various tissues of R. venosa, laying the groundwork for future investigations into the molecular mechanisms that shape the unique biology, ecology, and behaviour of the marine gastropods.