Integrated application of transcriptomics and metabolomics provides insights into the larval metamorphosis of pearl oyster (Pinctada fucata martensii)

Abstract

Larval metamorphosis, the planktonic larvae transited into benthic juveniles, is a short important phase for mollusks. However, information about the mechanism of its larval settlement and metamorphosis of Pinctada fucata martensii is still limited. In this study, metabolomic and transcriptomic approaches were applied to assess the metabolic and transcript changes among the different larval stage groups of P. f. martensii to understand the mechanism. In the metabolomics assay, 71 pathways of significantly different metabolites (SDM), including phenylalanine, tyrosine, and tryptophan biosynthesis; ubiquinone and other terpenoid–quinone biosynthesis; phenylalanine metabolism and d-glutamine and D-glutamate metabolism, were identified between the eyed larvae and the spat. Fifty-seven pathways of SDMs, including d-glutamine and D-glutamate metabolism; phenylalanine, tyrosine, and tryptophan biosynthesis; arachidonic acid metabolism; ubiquinone and other terpenoid–quinone biosynthesis and steroid hormone biosynthesis, were identified between the spat and the juvenile. The transcriptome analysis showed that 4561 and 915 differentially expressed genes (DEG) were identified between the eyed larvae and the spat stages and between the spat and the juvenile stages, respectively. The pathway enrichment analysis in DEGs associated with the neurotransmitter showed that cholinergic, glutamatergic, GABAergic, and serotonergic synapse pathways were significantly enriched between the eyed larvae and the spat stages. This study is the first work involving the integrated metabolomic and transcriptomic analyses to identify the key pathways and understand the molecular and the metabolic mechanisms underlying the larval metamorphosis of P. f. martensii.