Metabolomic analyses reveal the crucial metabolites involved in the transplantation response of pearl oyster Pinctada fucata martensii

The immune response after transplantation during pearl production is a major factor that cause nucleus rejection and death of the host pearl oysters. To find out the crucial metabolites involved in the immune response after transplantation, we performed metabolomic analysis of the serum before and after transplantation from pearl oyster Pinctada fucata martensii. The analysis detected a total of 201 metabolites, which included many amino acids. Among the 201 metabolites, 35 were revealed as significantly differential metabolites (SDMs), such as acetylcholine (ACh) and D-glutamine. Pathway analysis indicated that the identified SDMs were involved in six pathways, such as sphingolipid metabolism and D-glutamine and D-glutamate metabolism. Transcriptomic analysis showed 19 and 18 nAChRs were induced by 2-3000-fold through the pre-conditioning treatment or transplantation surgery, respectively. Dual-Luciferase analysis demonstrated that overexpression of nAChRs downregulated the luciferase activity of the pNF-kappa B-Luc reporter, and stimulation of nAChRs could inhibit the LPS-induced up-regulation of NF-kappa b, IKK and IL-17, suggesting that the upregulated ACh after transplantation may function through nAChRs by inhibiting NF-kappa b signal pathway. These findings could help elucidate the corresponding metabolites after transplantation, thereby providing useful information in regulating the immune response to improve the survival rate of pearl oyster after transplantation.

Automated summary

Metabolomic analysis of pearl oysters before and after transplantation identified 35 significantly differential metabolites involved in immune response, with pathways such as sphingolipid metabolism and D-glutamine metabolism. Upregulation of nAChRs and ACh after transplantation may function through inhibiting the NF-kappa b signal pathway, potentially improving the survival rate of pearl oysters.