Metabolomic analysis of competent larvae and juvenile veined rapa whelks ( Rapana venosa )

Metamorphosis of a planktonic larval stage to a benthic juvenile is an important process in many marine invertebrates including the whelk, Rapana venosa, but understanding of the variety of molecular mechanisms underlying metamorphosis in different invertebrate clades is still poor. The present study examined the metabolic profiles of competent larval and post-larval stages of R. venosa using GC-MS. The whelk egg capsules were collected in Laizhou Bay, Shandong, China, in June 2015, and the larvae and post-larvae were cultured in the laboratory. A total of 263 metabolites were detected, 53 of which had different concentrations in larvae and post-larvae: 29 that were apparently higher following metamorphosis and 24 that were lower. Among the metabolites whose concentrations were higher in post-larvae, quinoline-4-carboxylic acid, the dipeptide cysteinylglycine, and anandamide were the most abundant. The metabolites present in higher concentrations in the competent larvae were a suite of oligosaccharides ( maltotriose, glucose-6-phosphate, cellobiose, and maltose), L-homoserine, adrenosterone, and sarcosine. Although the roles of these and other metabolites in whelk development are not yet completely known, they provide some clues to the changes in energy metabolism and cell signaling that take place during metamorphosis.