Browsing by Author "Liqiao Chen"

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    Dietary L-carnitine improves glycogen and protein accumulation in Nile tilapia via increasing lipid-sourced energy supply: an isotope-based metabolic tracking. Aquaculture Reports, 17: 100302.
    (Elsevier, 2020-07) Ling-Yu Li; Dong-Liang Lu; Zhe-Yue Jiang; Samwel Mchele Limbu; Fang Qiao; Liqiao Chen; Meiling Zhang; Zhen-Yu Du
    L-carnitine is a functional aquafeed additive for enhancing lipid catabolism by elevating mitochondrial fatty acid β-oxidation and modulating energy metabolism to provide a “protein sparing effect”. However, results on the effects of dietary l-carnitine on nutrient metabolism in fish are still conflicting. We explored comprehensively the effects of dietary l-carnitine on energy metabolism in Nile tilapia. We fed Nile tilapia for eight weeks with diets supplemented with l-carnitine or not. We conducted metabolic tracking tests by intraperitoneally injecting individual fish with 14C-labeled palmitic acid (PA), glucose (Glu) and an amino acid mixture (AAs). After the feeding trial, insignificant growth-promoting effect of l-carnitine was obtained in treated fish. However, l-carnitine significantly reduced the lipid content in whole body and muscle accompanied by increasing the free carnitine concentration and fatty acid β-oxidation efficiency. Moreover, l-carnitine elevated concentrations of serum glucose, pyruvate and lactate, and increased glycogen and protein deposition in muscle. These results suggest that ingested glucose and protein prefer to be reserved in carnitine-fed fish with sufficient fatty acids oxidation for energy. Nevertheless, after a 14C-labeled single nutrient injection, carnitine-fed fish showed a higher oxidation rate of [1-14C]-PA, d-[1-14C]-Glu and l-[14C (U)]-AAs. Our study indicates that, the effects of l-carnitine on nutrient metabolism are correlated with the abundance of individual macronutrients such that an inadequate lipid supply would cause dietary l-carnitine supplementation to elevate higher breakdown of glucose and protein for energy generation. The present study provides new insights on the regulation mechanism of l-carnitine on nutrient metabolism in fish.
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    Dietary mannan oligosaccharide (MOS) improves growth performance, antioxidant capacity, non-specific immunity and intestinal histology of juvenile Chinese mitten crabs (Eriocheir sinensis). Aquaculture, 510: 337–346.
    (Elsevier, 2019-08-15) Jian-Ting Lu; Changle Qi; Samwel Mchele Limbu; Fenglu Han; Jian Qin; Liqiao Chen; Lu Yang; Xiaodan Wang
    Mannan oligosaccharide (MOS) is a common prebiotics to improve health and immunity of animals in aquaculture. However, its optimum level and effects on the immune response in crab are currently unknown. The present study investigated the optimum level of dietary MOS supplementation and its effects on growth performance, antioxidant capacity, non-specific immunity and intestinal morphology of juvenile Chinese mitten crab (Eriocheir sinensis). Crab juveniles (2.95 ± 0.05 g) were fed either a control diet or one of the six diets supplemented with MOS (0.1%, 0.2%, 0.3%, 0.4%, 0.5% and 0.6%) for eight weeks. The crabs fed 0.3% MOS showed greater weight gain, specific growth rate and lower feed conversion ratio than those fed the control diet. The acid phosphatase activity was significantly higher in the gut of crab fed 0.2% MOS than those fed the other diets except the 0.3% MOS diet. The lysozyme and alkaline phosphatase activities in the gut were higher in crabs fed the 0.1% and 0.3% MOS diets compared to those fed other diets. The antioxidant capacity was higher in crab fed the 0.2% and 0.3% MOS diets than those fed other diets. In addition, the mRNA expression of genes related to immunity (E. sinensis (Es)-Crustin, Es-Toll2, Es-Lech and Es-prophenoloxidase (proPO)) in the hepatopancreas of crabs fed the 0.2 and 0.3% MOS diets were significantly up-regulated compared with those fed other diets. Duplicature length and width increased significantly in the crab fed 0.3% MOS than other diets. The optimum inclusion levels of MOS were 0.32%, 0.20% to 0.30% and 0.27% to 0.29% based on growth performance, antioxidant capacity and immunity, respectively. This study indicates that supplementing diets with MOS at 0.2% to 0.3% can improve growth performance and enhance antioxidant capacity and immunity in E. sinensis.
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    A global analysis on the systemic effects of antibiotics in cultured fish and their potential human health risk: A review. Reviews in Aquaculture, 13(2): 1015–1059
    (Wiley, 2021-03) Samwel Mchele Limbu; Liqiao Chen; Meiling Zhang; Zhen-Yu Du
    The rearing of fish in intensive systems reduces their immunity leading to eruption of diseases, consequently prompting the use of antibiotics. Antibiotics are currently used in cultured fish globally to treat/prevent diseases. On the one hand, antibiotics used in aquaculture help to improve fish health by killing or inhibiting pathogenic bacteria proliferation. However, on the other hand, they cause multiple side effects. To date, information on systemic effects of antibiotics in cultured fish is scattered and their potential human health risk remains elusive. This review critically analyses and discusses the available information in the literature on the positive and negative effects of antibiotics in cultured fish and their potential human health risk via fish consumption. The review found 44 different antibiotics dominated by oxytetracycline were studied in various fish species worldwide. Antibiotics used in global aquaculture either decrease or increase fish growth and survival rates. They induce oxidative stress, which affect antioxidant and detoxification responses and cause host–microbiota dysbiosis. These changes compromise the fish immunity system, which ultimately lead to cellular damage. The toxicities generated inhibit the fish aerobic glycolysis, suppress lipogenesis and fatty acid β‐oxidation while increase energy demand by initiating gluconeogenesis and anaerobic glycolysis. Consumption of fish treated with antibiotics causes human health risk. Future studies are required on agents to restore dysfunctions induced by antibiotics in cultured fish, while attempts to limit their utilisation in aquaculture production are underway.
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    Gnotobiotic models: Powerful tools for deeply understanding intestinal microbiota-host interactions in aquaculture. Aquaculture, 517: 734800. https://doi.org/10.1016/j.aquaculture.2019.734800.
    (Elsevier, 2020-02-25) Meiling Zhang; Chengjie Shan; Fang Tan; Samwel Mchele Limbu; Liqiao Chen; Zhen-Yu Du
    Intestinal microbiota plays profound roles in host nutrition, physiology, and evolution. The development of DNA sequencing technologies has increased dramatically research on fish intestinal microbiota. However, most studies conducted so far have focused on the microbial structure and diversity. Studies targeting the exact function of commensal microbes in aquatic animals are still scarce, which limits the application of microbiota related knowledge in aquaculture. Gnotobiotic models (animals cultured in axenic conditions or with defined microbial lineages) are excellent tools for identifying the molecular interactions between intestinal microbiota and host, which drive studies of microbiota from correlation to causality in mammals. In recent decades, gnotobiotic fish models have been established and applied in aquaculture research. This review summarizes the colonization conditions in gnotobiotic zebrafish model and its application in understanding intestinal microbiota-host interactions in aquaculture. Furthermore, methods and research progress on other gnotobiotic models including freshwater and marine fishes, molluscs and crustaceans are also discussed. Application of gnotobiotic models in aquaculture has deepened our understanding of the relationship between the host and intestinal microbiota, which will facilitate the modulation of intestinal microbiota for production of healthy animals and sustainable development of aquaculture.