Understanding microRNA Regulation Involved in the Metamorphosis of the Veined Rapa Whelk (Rapana venosa)

The veined rapa whelk (Rapana venosa) is widely consumed in China. Nevertheless, it preys on oceanic bivalves, thereby reducing this resource worldwide. Its larval metamorphosis comprises transition from pelagic to benthic form, which implicates considerable physiological and structural changes and plays vital roles in its natural populations and commercial breeding. Thus, understanding the endogenous microRNAs that drive metamorphosis is of great interest. This is the first study to use high-throughput sequencing to examine the alterations in microRNA (miRNA) expression that occur during metamorphosis in a marine gastropod. A total of 195 differentially expressed miRNAs was obtained. Sixty-five of these were expressed during the transition from pre-competent- to competent larvae. Thirty-three of these were upregulated and the others were downregulated. Another 123 miRNAs were expressed during the transition from competent- to post-larvae. Ninety-six of these were upregulated and the remaining 27 were downregulated. The expression of miR-276-y, miR-100-x, miR-183-x, and miR-263-x showed an over 100-fold change during development, while the miR-242-x and novel-m0052-3p expression levels changed over 3000-fold. Putative target gene co-expression, gene ontology, and pathway analyses suggest that these miRNAs play important roles in cell proliferation, migration, apoptosis, metabolic regulation, and energy absorption. Twenty miRNAs and their target genes involved in ingestion, digestion, cytoskeleton, cell adhesion, and apoptosis were identified. Nine of them were analysed with real-time PCR, which showed an inverse correlation between the miRNA and their relative expression levels. Our data elucidates the role of microRNAs in R. venosa metamorphic transition and serve as a solid basis for further investigation into regulatory mechanism of gastropod metamorphosis.

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