Wenzong Zhou

The rice field eel (Monopterus albus) is an economically important aquaculture species widely distributed in Southeast Asia. However, the lack of nationally approved varieties and the increasing demand for high-quality eel products have highlighted the necessity of developing improved germplasm resources for aquaculture production. In this study, morphometric morphology and muscle texture traits were evaluated in 367 wild eel individuals, and a genome-wide association study (GWAS) based on whole-genome resequencing was conducted to identify genetic variants and candidate genes associated with economically important traits, including body length (BL), tail length (TL), tail height (TH), head length (HL), head width (HW), head height (HH), hardness, chewiness, springiness, and resilience. The GWAS identified three significant and seventeen suggestive SNPs associated with body shape traits, with most loci located on chromosome 4. Candidate gene analysis of the associated genomic regions revealed several candidate genes potentially associated with growth regulation, nutrient metabolism, and skeletal development, including b4galnt4a, tmem86a, cpt1b, mrpl23, lama1, gcm2, wnt3a, thrab, and bmpr1a. Additionally, four suggestive SNPs associated with muscle texture traits were detected, and candidate genes related to muscle development and extracellular matrix regulation, including fstl1b, col5a3a, and pnn, were identified. These findings provide new insights into the genetic basis underlying morphometric variation and muscle texture diversity in M. albus. The identified SNP markers and candidate genes provide potential molecular resources for understanding the genetic basis of body morphology and muscle texture variation in rice field eel.

Intensive aquaculture of rice field eel (Monopterus albus) is constrained by oxidative stress induced by high-density culture resulting in growth inhibition, while prophylactic antibiotics pose escalating risks of drug resistance and food safety hazards. This study addresses the critical need for developing efficient, environmentally friendly functional feed additives as sustainable growth promoters in intensive aquaculture. To investigate the dietary berberine (BBR) effect on promoting growth performance, hepatic antioxidant capacity and metabolism in M. albus, four experimental groups were established: control (CON, 0 mg/kg) and berberine-supplemented groups (BBR25, 25 mg/kg; BBR50, 50 mg/kg; BBR100, 100 mg/kg). Growth performance, serum biochemical parameters, hepatic antioxidant capacity, and liver metabolomics (LC-MS) were evaluated after the 8-week feeding trial. BBR50 and BBR100 had significantly increased final weight, weight gain rate (WG), and survival rate (SR), while reducing feed conversion ratio (FCR) (p < 0.05). Serum glucose (Glc), total cholesterol (TC), triglycerides (TG), and low-density lipoprotein cholesterol (LDL-C) were decreased (p < 0.05), while high-density lipoprotein cholesterol (HDL-C) and phosphofructokinase (PFK) activity were increased (p < 0.05). Alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) were significantly reduced (p < 0.05). Superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) were upregulated (p < 0.05), whereas malondialdehyde (MDA) was downregulated (p < 0.05). Metabolomics identified 98 differential metabolites, with significant enrichment of metabolites associated with arachidonic acid metabolism, histidine metabolism, arginine/proline metabolism, tryptophan metabolism, and pathways related to mTOR signaling. Overall, dietary supplementation with 50 mg/kg BBR emerged as a practically favorable dose among the tested concentrations for promoting growth performance and feed utilization efficiency, whereas 100 mg/kg BBR was associated with lipid and amino acid metabolic alterations suggestive of metabolic reprogramming and antioxidant-related shifts, without conferring additional growth benefits.

Membrane fouling induced by intracellular organic matter (IOM) presents a major challenge in the ultrafiltration (UF) of algal-laden water. While extracellular organic matter (EOM) has been widely studied, the role of IOM and its control mechanism remain insufficiently understood. This study systematically investigated the mitigation of IOM-induced UF membrane fouling through heat-activated peroxymonosulfate (PMS) pre-oxidation. The effects of varying PMS dosages (0.2–0.8 mM) on fouling behavior and mechanisms were thoroughly evaluated. The results demonstrated that the IOM released by Chlorella caused severe membrane fouling during UF. Membrane fouling was significantly mitigated after heat-activated PMS pretreatment when the dosage exceeded 0.2 mM, with the optimal performance obtained at the PMS dosage of 0.6 mM. PMS pretreatment effectively removed macro and medium molecular organics in IOM that were primarily responsible for membrane fouling. Moreover, PMS pretreatment influenced the surface morphology and hydrophobicity of the fouling layer. The interaction energy between the membrane and foulants was also changed. The fouling mechanism exhibited a shift in the dominant mode, while the untreated IOM primarily caused cake layer formation, and PMS pre-oxidation altered the fouling behavior toward pore blocking. Collectively, this research proposed a practical strategy to mitigate membrane fouling induced by IOM in the UF of algal-laden water.

As consumer demand for quality fish products continues to rise, quality has become a key factor in market competition. Ecological aquaculture research is exploring various farming methods to balance high-quality demand with environmental protection. This study compared three aquaculture models—cage culture (CG), recirculating aquaculture (RAG), and rice–fish co-culture (RG)—by analyzing muscle quality (AOAC, GC-MS), intestinal microbiota (16S rRNA), and liver metabolism (LC-MS) to assess their effects on M. albus. In terms of muscle quality, the RG group showed increased levels of EPA and DHA, reduced muscle moisture and crude lipid content, and enhanced crude protein accumulation. The crude protein content was significantly higher in the RAG group than in the CG group (p < 0.05). The RG group also had the highest levels of total, essential, and umami amino acids, followed by the RAG and CG groups. In terms of intestinal microbiota, the RG group had the highest microbial diversity and stability, with increased abundance of Firmicutes and Bacteroidetes and decreased levels of Proteobacteria. Compared to the CG, the RAG group also showed increased microbial diversity and a reduction in pathogenic genera. Liver metabolomics analysis demonstrated that the RG group had significant advantages over the CG group in amino acid, lipid, and energy metabolism. The RAG group exhibited upregulation of glycerophospholipid metabolism and a decrease in oxidative stress marker levels. Overall, the RG group enhanced muscle quality and optimized intestinal and liver metabolism in M. albus.

To investigate the dietary effects of Astragalus polysaccharides (APSs) on the growth performance, lipid metabolism, antioxidant activity, and non-specific immunity of Asian swamp eel (Monopterus albus) during the domestication stage, fish were randomly allocated into quadruplicate groups receiving Tenebrio molitor-based diets supplemented with Astragalus polysaccharides (APSs) at graded concentrations of 0 (CON), 700 (APS1), 1400 (APS2), and 2100 (APS3) mg/kg body weight for 28 days. The results showed that dietary APSs at 700–1400 mg/kg·bw significantly enhanced the weight gain rate (WG) and decreased the feed conversion ratio (FCR) of M. albus (p < 0.05). Concurrently, hematological analysis revealed that hemoglobin levels increased by 19.9% and 23.0% in the 700 and 1400 mg/kg APS groups, respectively (p < 0.05). In terms of lipid metabolism, supplementation with APSs significantly increased the serum high-density lipoprotein (HDL) content in all treatment groups (p < 0.05). Lower serum triglyceride (TG) levels were found in the APS2 group (p < 0.05), and decreased triglyceride (TG), cholesterol (CHO), and low-density lipoprotein (LDL) levels were displayed in the APS3 group (p < 0.05). Among the antioxidant parameters, the supplementation with 700 mg/kg·bw APSs significantly increased the glutathione peroxidase (GSH-Px) and catalase (CAT) activity levels of M. albus (p < 0.05). The APS2 group had a significantly increased total antioxidant capacity (T-AOC) and CAT activity levels (p < 0.05), and the APS3 group had significantly increased CAT activity levels (p < 0.05). In addition, the APS1 and APS3 groups had significantly reduced malondialdehyde (MDA) levels (p < 0.05). In terms of non-specific immunity, the APS1 and APS2 groups showed significantly increased superoxide dismutase (SOD) and lysozyme (LZM) activity levels of M. albus (p < 0.05), and the addition of 700 mg/kg·bw APSs significantly increased the levels of alkaline phosphatase (AKP) activity (p < 0.05). Furthermore, the levels of acid phosphatase (ACP) activity were significantly increased in all experimental groups (p < 0.05). In conclusion, the optimal APS addition for T. molitor as biocarrier bait is 700 mg/kg, corresponding to 352 mg/kg, which elicits improvements in the growth parameters, lipid homeostasis regulation, oxidative stress mitigation, and innate immune potentiation of M. albus during the domestication stage.

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.