Suspension-feeding bivalves, including the oyster Crassostrea virginica, use mucosal lectins to discriminate and capture food particles via interactions with particle surface carbohydrates. Endogenous factors, and most specifically neuropeptides, affecting the expression of mucos al lectins and feeding processes remain unclear.
The aim of this study was to interrogate the genome of C. virginica to identify and characterize putative neuropeptide genes. A special focus was given to genes with potential function in feeding processes . Thus, the main organs of expression of these genes were determined using quantitative PCR. Further, synthetic neuropeptide F (NPF) and visceral ganglia extracts were injected to oysters to evaluate their impact on genes involved in feeding processes and energy homeostasis.
A total of 61 neuropeptide genes, including duplicated genes, were identified in the C. virginica genome, and homologs of more than 50% of these have been suggested to play a role in feeding process es in other invertebrates. Gene expression analyses showed that the visceral and cerebral ganglia and the digestive system are the main organs involved in neuropeptide production. Further, the expression of several neuropeptide genes, including NPF and insulin-like peptides, increased after starvation. Finally, the injection of visceral ganglia extracts and synthetic NPF significantly increased the expression of a mucosal lectin and a glycogen synthase, which are known to be involved in particle capture and glucose storage, respectively.
This study presents the first neuropeptidome in C. virginica and points to some neuropeptides that are involve in the control of the feeding process and energy homeostasis in oyster.