Background: Laying hens over 75 weeks of age commonly show great declines in immunity and production performance.It is unclear whether these declines can be relieved by supplementing with ascorbic acid(AA) in feed.Two...Background: Laying hens over 75 weeks of age commonly show great declines in immunity and production performance.It is unclear whether these declines can be relieved by supplementing with ascorbic acid(AA) in feed.Two trials were conducted to investigate the synthesis and metabolism of AA in layers of different ages and the effects of dietary supplemental AA on the performance and the immune and antioxidant statuses of 78 weeks old hens.Methods: In Exp.1,equal numbers(24 hens) of 35 weeks old(Young) and 75 weeks old(Old) layers were fed the same diet without AA supplementation for 4 weeks.In Exp.2,360 healthy 78 weeks old laying hens were randomly assigned to 4 treatments(basal diet supplemented with 0,0.25,0.5,or 1 g AA/kg diet) in an 8-week feeding trial.Results: The old hens tended to have decreased L-gulonolactone oxidase(GLO) synthase activity in the kidney and liver than that of the young hens(P = 0.07 and P = 0.05,respectively).Compared with the young hens,the old hens had lower hepatic antioxidant capacity allowing for the lower thioredoxin(TXN),thioredoxin reductase(TXNR) and cytochrome b5 reductase(CYB5 R) gene expression(P < 0.05),whereas increased sodium-dependent vitamin C transporter(SVCT) 1 expression levels in the ileum and kidney and enhanced splenic and hepatic AA concentrations(P < 0.05).Dietary supplementation with AA significantly decreased GLO enzyme activity but increased splenic AA concentration and anti-bovine serum albumin IgG levels(P < 0.05) and tended to increase CD4+T lymphocyte numbers(P = 0.06) in serum.Supplementation of 0.25 g AA/kg diet significantly increased hepatic total antioxidant capacity(T-AOC,P < 0.05) relative to the control group.Conclusions: Laying hens could synthesize AA in both the kidney and the liver,though the GLO enzyme activities were 100 times greater in kidneys than in livers.The old laying hens had greater absorption and reabsorption capacity and higher AA retention in some tissues that did the young hens.Dietary supplementation of AA can improve the health of old layers by enhancing immunity and antioxidant capacity.展开更多
Nanomaterial-based artificial enzymes（nanozymes） have shown great potential for application in colori- metric sensing. In this paper, the nanocomposites of CeO2 and reduced graphene oxide（rCK）） were fabricated vi...Nanomaterial-based artificial enzymes（nanozymes） have shown great potential for application in colori- metric sensing. In this paper, the nanocomposites of CeO2 and reduced graphene oxide（rCK）） were fabricated via a one-pot hydrothermal process, in which CeO2 nanoparticles were well anchored on the surface of rGO. The prepared CeO2/rGO nanocomposites exhibited excellent catalytic activity for the oxidation of 3,3＇,5,5＇-tetramethylbenzidine（TMB） in the presence of 02. Compared with the individual CeO2 nanoparticles, the nanocomposites had a higher affinity and adsorptivity towards the substrate TMB, which was due to the combination of rGO. In addi- tion, based on the oxidase-like activity of CeO2/rGO nanocomposites, a facile and sensitive colormetric sensor for ascorbic acid（AA） was investigated. The detection limit of AA was low（0.15μmol/L） and the linear detection range was between 0.5μmol/L and 40μmol/L. Fttrthermore, the colorimetric system was used for the detection of AA in medicine and food analysis, such as tablets, beverage and milk powder.展开更多
利用亚洲首个开放式臭氧浓度升高(Ozone-free air controlled enrichment)平台,以武运粳21(粳稻)和两优培九(杂交稻)两个耐性不同的水稻品种为材料,研究了大气臭氧浓度升高对水稻叶片乙醇酸氧化酶(GO)、多酚氧化酶(PPO)和抗坏血酸氧化酶...利用亚洲首个开放式臭氧浓度升高(Ozone-free air controlled enrichment)平台,以武运粳21(粳稻)和两优培九(杂交稻)两个耐性不同的水稻品种为材料,研究了大气臭氧浓度升高对水稻叶片乙醇酸氧化酶(GO)、多酚氧化酶(PPO)和抗坏血酸氧化酶(AAO)3种呼吸作用相关酶的影响,初步探讨了高臭氧浓度条件下水稻不同基因型对臭氧胁迫响应机制的差异性。结果表明:臭氧处理67天,促进了GO、PPO和AAO的活性,武运粳21升高的幅度(24.6%、9.25%和67.8%)大于两优培九的升高幅度(11.18%、7.26%和36.85%);在处理79天,臭氧胁迫抑制了水稻叶片GO、PPO和AAO的活性,品种间比较,武运粳21的3种酶降低的幅度(21.18%、6.14%和31.87%)小于两优培九(42.7%、33.93%和51.1%)。结果说明,武运粳21在通过提高3种酶的活力而进行较强的呼吸作用,起到耗散过剩光能并保护光合器官的作用,从而缓解臭氧对光合器官的损害缓解臭氧对水稻叶片造成的伤害,因此武运粳21比两优培九对臭氧耐受性强。展开更多
基金The State Key Development Program(2016YFD0501202)supported this study
文摘Background: Laying hens over 75 weeks of age commonly show great declines in immunity and production performance.It is unclear whether these declines can be relieved by supplementing with ascorbic acid(AA) in feed.Two trials were conducted to investigate the synthesis and metabolism of AA in layers of different ages and the effects of dietary supplemental AA on the performance and the immune and antioxidant statuses of 78 weeks old hens.Methods: In Exp.1,equal numbers(24 hens) of 35 weeks old(Young) and 75 weeks old(Old) layers were fed the same diet without AA supplementation for 4 weeks.In Exp.2,360 healthy 78 weeks old laying hens were randomly assigned to 4 treatments(basal diet supplemented with 0,0.25,0.5,or 1 g AA/kg diet) in an 8-week feeding trial.Results: The old hens tended to have decreased L-gulonolactone oxidase(GLO) synthase activity in the kidney and liver than that of the young hens(P = 0.07 and P = 0.05,respectively).Compared with the young hens,the old hens had lower hepatic antioxidant capacity allowing for the lower thioredoxin(TXN),thioredoxin reductase(TXNR) and cytochrome b5 reductase(CYB5 R) gene expression(P < 0.05),whereas increased sodium-dependent vitamin C transporter(SVCT) 1 expression levels in the ileum and kidney and enhanced splenic and hepatic AA concentrations(P < 0.05).Dietary supplementation with AA significantly decreased GLO enzyme activity but increased splenic AA concentration and anti-bovine serum albumin IgG levels(P < 0.05) and tended to increase CD4+T lymphocyte numbers(P = 0.06) in serum.Supplementation of 0.25 g AA/kg diet significantly increased hepatic total antioxidant capacity(T-AOC,P < 0.05) relative to the control group.Conclusions: Laying hens could synthesize AA in both the kidney and the liver,though the GLO enzyme activities were 100 times greater in kidneys than in livers.The old laying hens had greater absorption and reabsorption capacity and higher AA retention in some tissues that did the young hens.Dietary supplementation of AA can improve the health of old layers by enhancing immunity and antioxidant capacity.
基金Supported by the National Natural Science Foundation of China（No.21675008） and the Fundamental Research Funds for the Central Universities of China（No.JD1516）.
文摘Nanomaterial-based artificial enzymes（nanozymes） have shown great potential for application in colori- metric sensing. In this paper, the nanocomposites of CeO2 and reduced graphene oxide（rCK）） were fabricated via a one-pot hydrothermal process, in which CeO2 nanoparticles were well anchored on the surface of rGO. The prepared CeO2/rGO nanocomposites exhibited excellent catalytic activity for the oxidation of 3,3＇,5,5＇-tetramethylbenzidine（TMB） in the presence of 02. Compared with the individual CeO2 nanoparticles, the nanocomposites had a higher affinity and adsorptivity towards the substrate TMB, which was due to the combination of rGO. In addi- tion, based on the oxidase-like activity of CeO2/rGO nanocomposites, a facile and sensitive colormetric sensor for ascorbic acid（AA） was investigated. The detection limit of AA was low（0.15μmol/L） and the linear detection range was between 0.5μmol/L and 40μmol/L. Fttrthermore, the colorimetric system was used for the detection of AA in medicine and food analysis, such as tablets, beverage and milk powder.
文摘利用亚洲首个开放式臭氧浓度升高(Ozone-free air controlled enrichment)平台,以武运粳21(粳稻)和两优培九(杂交稻)两个耐性不同的水稻品种为材料,研究了大气臭氧浓度升高对水稻叶片乙醇酸氧化酶(GO)、多酚氧化酶(PPO)和抗坏血酸氧化酶(AAO)3种呼吸作用相关酶的影响,初步探讨了高臭氧浓度条件下水稻不同基因型对臭氧胁迫响应机制的差异性。结果表明:臭氧处理67天,促进了GO、PPO和AAO的活性,武运粳21升高的幅度(24.6%、9.25%和67.8%)大于两优培九的升高幅度(11.18%、7.26%和36.85%);在处理79天,臭氧胁迫抑制了水稻叶片GO、PPO和AAO的活性,品种间比较,武运粳21的3种酶降低的幅度(21.18%、6.14%和31.87%)小于两优培九(42.7%、33.93%和51.1%)。结果说明,武运粳21在通过提高3种酶的活力而进行较强的呼吸作用,起到耗散过剩光能并保护光合器官的作用,从而缓解臭氧对光合器官的损害缓解臭氧对水稻叶片造成的伤害,因此武运粳21比两优培九对臭氧耐受性强。
