Understanding the internal differences behind unsynchronized growth in sea cucumber Holothuria leucospilota by integration of transcriptomic and metabolomic data

In China, there is a rapidly increasing need for the seedlings of tropical sea cucumber, Holothuria leucospilota, as they are often used for releasing to restore fishery resources and marine environments. Unsynchronized growth (NG) of H. leucospilota has been a problem during its culture, and the molecular mechanisms behind NG are rarely explored. In the present study, unsynchronized growing seedlings of H. leucospilota cultured in same environment were random collected after 100 days rearing, and they were classified into a fast-growing (FG) group and a slow-growing (SG) group based on their body weight. Body wall tissues were sheared for metabolomic analysis based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) and transcriptomic analysis with RNA sequencing (RNA-seq). 3243 Differentially expressed genes (DEGs) and 1574 different metabolites (DMs) were identified between two group. Integrated metabolomic and transcriptomic analysis revealed 47 jointly enriched pathways and the FG group had a better capacity for protein and fatty acid synthesis, vitamin synthesis, and oxidative stress regulatory while the SG group experienced more frequent apoptosis. The results facilitate to discover underlying mechanism of NG, which offers prospective benefits for the aquaculture of sea cucumbers.