果蔬氧化还原防御系统研究进展

果蔬的成熟和衰老受体内氧化还原防御系统的调控,果蔬体内的氧化还原防御系统能够及时清除自身产生的活性氧并维持动态平衡,然而逆境胁迫将引起活性氧的过量积累,导致果蔬发生氧化损伤,进而加速其衰老进程,直接影响果蔬采后的品质和贮藏时间。本文总结了采后果蔬活性氧产生及其诱导果蔬品质劣变的机理,分析了果蔬体内的酶促抗氧化体系和非酶促抗氧化体系,并阐明了其清除活性氧的机制,为维持果蔬采后的贮藏品质提供参考。     

Effects of dietary energy on antioxidant capacity,glucose–lipid metabolism and meat fatty acid profile of Holstein bulls at different ages

This experiment was conducted to investigate the effects of dietary energy on antioxidant capacity, liver glucose–lipid-related gene expressions and meat fatty acid of Holstein bulls. Thirty-six Holstein bulls (age, 17.0 ± 0.49 months; body weight, 493.3 ± 39.7 kg) were randomly allocated to three dietary treatments. The metabolizable energy of diets was 10.12, 10.90 and 11.68 MJ/kg. Bulls in each dietary treatment were sampled at the age of 20, 23 or 26 months. Results showed that serum glutathione peroxidase and superoxide dismutase decreased with the increasing age. Dietary energy and age had interaction effects on the expressions of fatty acid synthase, peroxisome proliferator-activated receptor alpha, acyl coenzyme A oxidase 1 and carnitine palmitoyl-transferase 1 alpha. Besides, the increase of age and dietary energy increased the expression of liver phosphoenolpyruvate carboxykinase 1. The expressions of liver glucose-6-phosphatase, tumour necrosis factor alpha and sterol regulatory element binding protein 1 increased with the increasing age. The increase of age and dietary energy increased the proportions of C18:1cis-9, C18:2n-6trans and monounsaturated fatty acid. In summary, the increase of age and dietary energy enhanced the intensity of metabolic changes and inflammatory responses. Dietary energy and age affected the expressions of liver lipid metabolism-related genes, further affected meat fatty acid composition of Holstein bulls.     

Effects of dietary vitamin C and vitamin E on the growth,antioxidant defence and digestive enzyme activities of juvenile discus fish (Symphysodon haraldi)

A 56‐day experiment was carried out to investigate the effects of dietary vitamin C and vitamin E on the growth, antioxidant status and digestive enzyme activities of discus fish (Symphysodon haraldi; initial body weight: 7.96 ± 0.61 g and body length: 5.45 ± 0.65 cm). Animals were fed with 13 different diets including one control diet and 12 treatment diets containing four levels of vitamin C (magnesium‐L‐ascorbyl‐2‐phosphate; 40, 80, 120 and 160 mg/kg) crossed with three levels of vitamin E (DL‐α‐tocopheryl acetate; 40, 80 and 120 mg/kg). The results showed that the fish fed diets containing additional vitamin C (40 mg/kg) and vitamin E (80 mg/kg) showed higher specific growth rate, length growth rate, total antioxidant capacity and protease activity but had lower feed conversion ratio and total superoxide dismutase activity than those fed the control diet. Collectively, these findings suggest that the inclusion of additional 40 mg/kg of vitamin C and 80 mg/kg of vitamin E in the basal diet could have beneficial effect on the growth, antioxidant defence and digestion of S. haraldi.     

Hypoxia‐induced changes in survival,immune response and antioxidant status of the Pacific white shrimp (Litopenaeus vannamei) fed with graded levels of dietary myo‐inositol

A 3‐hr experiment was conducted to investigate the effects of dietary myo‐inositol (MI) supplementation on survival, immune response and antioxidant abilities in Litopenaeus vannamei under acute hypoxia stress. Six practical diets were formulated with supplementation of graded levels (control group 0, 0.1, 0.2, 0.4, 0.8 and 1.6 g/kg dry diet) of MI and were randomly assigned to triplicate groups of L. vannamei (mean weight 0.40 ± 0.00 g) for 8 weeks. Ten healthy shrimp (final mean weight approximately 11–14 g) randomly selected from each tank were exposed to hypoxia stress after feeding trial. After 3‐hr acute hypoxia stress, survival of shrimp fed MI‐supplemented diets (except 0.1 and 0.4 g/kg diets) was significantly increased compared with the control group. Shrimp fed control diet had lower activities of alkaline phosphatase (AKP), acid phosphatase (ACP), total antioxidant capacity (T‐AOC) and glutathione peroxidase (GPX), and higher malondialdehyde (MDA) and protein carbonyl (PC) contents in hepatopancreas than those fed the MI‐supplemented diets. In addition, mRNA expression levels of heat shock protein 70 (Hsp70), catalase (CAT) and penaeidin were significantly differentially regulated in hepatopancreas. In summary, dietary MI supplementation may have a positive effect on improving resistance to acute hypoxia stress of L. vannamei.     

Dietary trans‐cinnamic acid application for rainbow trout (Oncorhynchus mykiss): II. Effect on antioxidant status,digestive enzyme,blood biochemistry and liver antioxidant gene expression responses

The present study investigated the effects of dietary trans‐cinnamic acid (TrCin) on growth performance, biochemical composition, fatty acid composition, blood biochemistry, antioxidant status, digestive enzyme and liver antioxidant gene (EF1α, SOD1, SOD2, CAT, GPX1, GPX4, GR and GST) expression responses of rainbow trout, Oncorhynchus mykiss. Five experimental groups of fish with mean weights of 17.49 ± 0.08 g were used in the study; four of them were fed with TrCin‐supplemented diets (0.25 g/kg TrCin25, 0.50 g/kg TrCin50, 0.75 g/kg TrCin75 and 1.50 g/kg TrCin150), whereas an additive‐free basal diet served as the control (Cntr). At the end of the 60‐day feeding trial, the growth performance, biochemical composition and fatty acid composition were similar for all experimental groups. A decrease was observed in intestinal and stomach pH, serum triglyceride and AST, ALT, LDH and ALP levels in fish fed with especially 0.50 g/kg TrCin‐supplemented diet. Moreover, dietary TrCin especially at 0.50 g/kg incorporation level significantly increased the serum SOD and liver SOD2, CAT, GST, GPX1, GPX4 and GR gene expression responses. As a conclusion, feeding rainbow trout for a period of 60 days with a diet containing 0.50 g/kg TrCin might be sufficiently enough to improve the levels of antioxidant enzymes and health status in fish.     

Characterization and expression of NADPH oxidase genes in stimulated splenic neutrophils of tilapia,Oreochromis niloticus by a mix of traditional Chinese medicine and Bacillus species (TCMBS)

Traditional Chinese medicine and Bacillus species (TCMBS) mixture is an immunostimulant with considerable promise as an alternative in improving fish health. However, nothing is known on its effects on the expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase genes and production of reactive oxygen species (ROS) in the neutrophils of fish. The full lengths of tilapia phagocytic NADPH oxidase genes gp91^phox, p22^phox, p40^phox, p47^phox, and p67^phox were cloned and their expression profiles after TCMBS stimulus investigated. The cDNAs of tilapia gp91^phox, p22^phox, p40^phox, p47^phox, and p67^phox contained open reading frames of 1698 bp, 561 bp, 1053 bp, 1584 bp, and 1470 bp respectively, encoding 561, 186, 350, 527, and 489 amino acids respectively. Comparison of the deduced amino acid sequences showed that tilapia NADPH oxidase genes shared 58%–91% and 21%–67% identity with those of other teleost and mammals respectively. Besides, tilapia NADPH oxidase genes contain conserved domains and motifs required for ROS generation. Phylogenetic analysis suggested tilapia NADPH oxidase genes were close to those of Fundulus heteroclitus. After 2 weeks of TCMBS application showed significant upregulation in expression of NADPH oxidase genes, antioxidant genes (i.e., superoxide dismutase, catalase, and glutathione‐disulphide reductase), and an increase in the production of ROS compared to the control in splenic neutrophils of tilapia. Collectively, our study provides evidence of the structure of tilapia NADPH oxidase genes and demonstrate that TCMBS application could modulate their activity in neutrophils to improve immunity in tilapia.     

水杨酸浸种对侧柏种子萌发及幼苗生理特性的影响

[目的]以侧柏(Platycladus orientalis(L.) Franco)种子为试验材料,通过对不同浓度水杨酸(SA)浸种处理下侧柏种子萌发指标、幼苗形态和生理指标的定量分析,研究SA对侧柏种子萌发特性和幼苗生长的影响,筛选出最佳的SA浸种浓度,为侧柏播种育苗的生产实践提供参考。[方法]设置0.5、1.0、1.5、2.0、3.0 mmol·L~(-1 )5个SA浓度,对侧柏种子进行浸种,蒸馏水浸种为对照,测定各处理种子发芽指标、形态指标、幼苗的抗氧化酶活性和丙二醛(MDA)含量指标。[结果]SA浸种可以显著提高侧柏种子的发芽率和发芽指数,1.5 mmol·L~(-1)处理的发芽率最高,为96.3%,比对照提高9.3%,3.0 mmol·L~(-1)处理的发芽指数最高,比对照提高26.5%;低浓度SA(≤1.0 mmol·L~(-1))有促进地上部分生长、抑制地下部分生长的效果;高浓度SA(≥1.5 mmol·L~(-1))则抑制地上部分生长,促进地下部分生长;超氧化物歧化酶(SOD)活性在SA浓度1.5 mmol·L~(-1)时最高,比对照提高69.0%;过氧化氢酶(CAT)活性随SA浓度的增大而升高,在1.5、2.0、3.0 mmol·L~(-1)处理下均高于对照,分别增加33.9%、10.7%、19.9%;随SA处理浓度的增大,MDA含量逐渐降低,但差异不明显,可能和SA促进抗氧化酶活性,减少膜脂过氧化,种子本身质量良好,且外界无逆境胁迫有关。[结论] 1.5～3.0 mmol·L~(-1 )SA处理对提高侧柏种子发芽率和幼苗SOD、CAT活性及促进幼苗地下部分生长效果较佳,但各浓度间的处理效果差异不显著。综合考虑生产成本等因素,建议生产实践中侧柏种子播种育苗时采用1.5 mmol·L~(-1 )SA浸种24 h。     

柠檬籽粒中柠檬苦素离子液体双水相提取体系的优化与抗氧化活性分析

为更好地开发和利用柠檬籽粒中的功能性成分柠檬苦素,本试验研究了离子液体双水相对柠檬苦素提取的最优体系,并通过响应面分析法对最优体系的提取工艺进行了优化。结果表明,1.50 mol·L^-1 [TMG][Cl]/1.35 mol·L^-1 NaH₂PO₄离子液体双水相萃取体系中柠檬苦素的提取量最高,萃取率达97.59%;响应面优化试验得出最优工艺参数:提取时间90.74 min、乙醇浓度59.40%、提取温度74.22℃、液料比18.08∶1条件下,预测柠檬苦素最大提取量为12.126 mg·g^-1FW,校正工艺下柠檬苦素实际提取量为12.381 mg·g^-1 FW,方差分析显示两数值差异不显著,表明有关柠檬苦素提取量的四元二次方程模型预测准确度高。此外,柠檬苦素可有效清除活性氧自由基并抑制不饱和脂肪酸的过氧化,具有较强的抗氧化活性。本研究结果为柠檬资源的充分开发和实际应用提供了理论基础。