Project description:<p>Macrobrachium rosenbergii is one of the most economically important crustaceans globally, but significant individual growth differences persist even under the same genetic background and rearing conditions, limiting the sustainability of its aquaculture industry. Metabolomics, as a powerful tool to characterize the terminal products of biological metabolism, can directly reflect the correlation between metabolic status and phenotypic traits. In this study, male and female M. rosenbergii from a single family were divided into three size groups (large, medium, and small) based on body weight: large males (ML, 64.2±1.48 g), medium males (MM, 40.8±0.90 g), small males (MS, 20.3±0.70 g); large females (FL, 61.4±1.46 g), medium females (FM, 43.6±0.85 g), small females (FS, 23.2±0.44 g). Serum samples were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS)-based untargeted metabolomics to identify differential metabolites (DMs), enrich metabolic pathways, and explore correlations with phenotypic traits, intestinal microbiota, and gonadal differentially expressed genes (DEGs). The partial least squares discriminant analysis (PLS-DA) showed clear separation among different size groups, indicating distinct serum metabolic profiles. A total of 37 DMs were screened with VIP 1 and P < 0.05, including amino acids, carbohydrates, lipids, and hormones. Specifically, L-tyrosine, phosphorylcholine, succinic acid, and acetylcholine were highly abundant in large-sized males, while oleic acid, L-ribulose, sucrose, and 17α-estradiol were enriched in large-sized females. In contrast, 4-hydroxycinnamic acid, equol, mannose 6-phosphate, and gluconic acid were more abundant in small-sized females. KEGG pathway enrichment analysis revealed that these DMs were significantly enriched in pathways related to growth and metabolism, such as 'amino acid biosynthesis', 'protein digestion and absorption', 'glycerophospholipid metabolism', and 'actin cytoskeleton regulation'. Pearson correlation analysis demonstrated that key DMs (e.g., acetylcholine, L-tyrosine, 17α-estradiol) were strongly positively correlated with growth-related phenotypic traits (body weight, carapace weight, body length, etc.). Additionally, significant correlations were observed between DMs and dominant intestinal microbiota (e.g., Lactococcus, Rhodobacter, Bacteroides) as well as gonadal DEGs (e.g., mhc, tpnc3, GHSR), constructing a multi-level regulatory network involved in M. rosenbergii growth. Our findings uncover the metabolic mechanisms underlying growth differences in M. rosenbergii and identify potential metabolic biomarkers for growth traits, providing valuable theoretical basis and technical support for molecular breeding to improve growth performance of this species.</p>
