The present study aimed to systematically investigate the underlying differences in flesh quality between wild and farmed Monopterus albus. Fifteen healthy M. albus per group with an average body weight of 45 g were sampled to analyze muscle parameters by biochemical indicators, histomorphology, and molecular biology. Compared with the wild fish, the farmed M. albus in flesh had lower crude protein, collagen, lysine, histidine, total amino acids, SFA, n-3 PUFA contents, and n-3/n-6 ratio (p < 0.05), and higher moisture, crude lipid, crude ash, MUFA, n-6PUFA, and total PUFA contents (p < 0.05). The thawing loss, drip loss, steaming loss, and boiling loss in the farmed group were significantly higher, and hardness, springiness, cohesiveness, gumminess, chewiness, and resilience were significantly lower than those in the wild group (p < 0.05). In addition, higher muscle fiber density and lower muscle fiber diameter were observed in wild M. albus (p < 0.05). In muscle transcriptome profiling, differentially expressed genes and enriched pathways are primarily associated with muscle development, protein synthesis, catabolism, lipid metabolism, and immunity. To the best of our knowledge, this is the first investigation that compares the flesh quality between wild and farmed M. albus in terms of biochemistry, histology, and molecular biology levels. Overall, wild M. albus had a higher nutritional value and texture quality than farmed M. albus.

To investigate the dietary effects of chlorogenic acid (CGA) on the growth performance, lipid metabolism, antioxidant activity, and non-specific immunity of Asian swamp eel (Monopterus albus) during the domestication stage, a 28-day feeding experiment was conducted to supplement with CGA at levels of 0 (Cont.), 250 (CGA 0.50%), 500 (CGA 1.00%), and 750 (CGA 1.50%) mg/kg·bw by feeding with yellow mealworm (Tenebrio molitor). Compared with the control group, the addition of 250–750 mg/kg of CGA significantly increased the weight-gain rate (WG) of M. albus, and the CGA 1.0% group displayed the highest value. The content of hemoglobin and high-density lipoprotein in all CGA groups was markedly elevated (p < 0.05), while the triglyceride, glucose, low-density lipoprotein, and glycosylated serum protein levels were lowered (p < 0.05). Among the antioxidant enzymes, the glutathione peroxidase and catalase activity was significantly higher in all experimental groups than that of the control group, whereas the malondialdehyde activity was significantly reduced (p < 0.05). For a non-specific immune enzyme system, the lysozyme and alkaline phosphatase activity in all treatments and the superoxide dismutase and acid phosphatase activity in the CGA 0.5% group was markedly increased (p < 0.05). In conclusion, supplementation with CGA can enhance the growth performance and improve the lipid metabolism, antioxidant capacity, and non-specific immunity of M. albus during the domestication stage, and the optimal CGA supplementation for T. molitor as biocarrier bait is 500 mg/kg, corresponding to 405 mg/kg.

Nanoplastics (NPs) have emerged as contaminants in recent years and have attracted widespread attention because of their ecotoxicological effects. This study aimed to document the effects of different concentrations of NPs on the Monopterus albus. M. albus. M. albus were orally administered three different concentrations of 100 nm polystyrene NPs (0.05%, 0.5%, and 1% of the feed) for 35 days. The effects of different NPs concentrations on energy metabolism, enzyme biomarker responses, gene expression responses, and amino acid changes were investigated in M. albus after exposure. The results revealed that the gene expression of phosphoenolpyruvate carboxykinase and glucose-6-phosphatase was up-regulated after the ingestion of high concentrations of NPs. The gluconeogenic pathway was inhibited, lactic acid (LA) content was increased, anaerobic glycolysis was used to produce LA to power the organism, and the accumulation of NPs led to a decrease in total cholesterol and triglyceride levels in liver tissues. There were increases in the relative liver content of glutamine, glycine, and methionine, which may be due to antioxidation in the liver. The stress may caused by NPs leads to the formation of some glutamylated amino acids, which are converted into glutathione to play an antioxidant role. NPs also induced lipotoxicity of the liver organoid by increasing lipid accumulation, these include methyl tetradecanoate (myristate), pentadecanoic acid, eicosanoic acid (arachidic acid), heptadecanoic acid (margaric acid), 5,8,11,14-eicosatetraenoic acid, and doconexent (Docosahexaenoic acid). Interestingly, some immune-related metabolites, such as 9-octadecenoic acid (oleic acid) and 9,12-octadecadienoic acid (linoleic acid), were significantly reduced, and these changes were probably caused by disturbances in hepatic lipid metabolism following NPs exposure.