活性氧在外源乙烯诱导内源乙烯产生过程中的作用

外源乙烯在一定的条件下明显抑制了超氧化物歧化酶（SOD)和过氧化氢酶（CAT）的活性,提高了超氧化物阴离子自由基和过氧化氢（H2O2）的产率,从而有效地诱导了内源乙烯产生的增加;外源和H2O2对乙烯产生的促进作用及外源活性氧清除剂对乙烯产生的抑制作用也为此提供了证明。乙烯对植物生理过程的调节机制之一就是通过影响活性氧清除酶活性,从而调节各种活性氧在体内的平衡。     

一株耐高温SOD产生菌的筛选及酶学特性

超氧化物歧化酶(Superoxide dismutase简称SOD)是生物体防御氧化损伤的金属酶。具有治疗炎症、抗辐射损伤、防癌、抗衰老等广泛药用前景。另外在植物抗逆和生物固氮等方面也有重要作用。自1969年McCord和Fridovich发现该酶以来,人们已从多种动植物和微生物中分离了此酶。SOD的基因工程也取得了令人瞩目的成就。相对而言,动植物Cu、Zn-SOD的研究较活跃,而微生物SOD,特别是Fe-SOD的研究较薄弱。本文报道耐高温SOD产生菌的筛选、鉴定结果,并对酶的稳定性和酶学特性作了研究。     

双歧杆菌抗衰老作用的初步研究

本文用双歧杆菌活菌液喂养老龄大白鼠,观察其血中抗衰老生化指标（ＳＯＤ、ＧＳＨ－Ｐｘ）和衰老生化指标（ＬＰＯ）的变化。试验组大鼠用双歧杆菌喂养两个月后,与对照组相比,前者血中ＳＯＤ活性显著升高（ｐ〈０．０１）,ＬＰＯ的含量显著低于对照组（ｐ〈０．０５）。采用自身对照,试验组大鼠用双歧杆菌喂养后与喂养前相比,ＳＯＤ活性显著升高（ｐ〈０．０１）,而ＬＰＯ的变化无显著性（ｐ〉０．０５）;对照组大鼠在试验期     

酸枣仁总皂甙对缺氧－再给氧心肌细胞的保护作用

按Laarse＇s方法建立培养心肌细胞缺氧-再给氧(A-R)模型,缺糖缺氧60min,再给氧30min.结果发现,缺氧组心肌细胞MDA含量增加,SOD活性降低,细胞膜脂质流动性下降,再给氧组上述改变加剧.酸枣仁总皂忒(ZS)能剂量依赖性地显著降低心肌细胞MDA含量,提高SOD活性,增加细胞膜脂质流动性,证明ZS有明显抗心肌细胞缺氧-再给氧损伤作用.     

Inhibition of replicon initiation by 12-O-tetradecanoylphorbol-13-acetate

To investigate the inhibition of DNA replication by tumor promoters, we incubated HeLa cells with 12-O-tetradecanoylphorbol-13-acetate (TPA; 10^?8 to 10^?5 g/ml) and quantified DNA synthesis on alkaline sucrose gradients. TPA was found to selectively inhibit replicon initiation without affecting DNA chain elongation in replicons that had already initiated. No inhibition of DNA synthesis was seen when cells were exposed to the nonpromoting derivative of TPA, 4-α-phorbol 12,13-didecanoate. Superoxide dismutase did not prevent the TPA-induced inhibition of initiation.     

Estimation of the Oxidative Stress and Molecular Damage Caused by 1‐Butyl‐3‐Methylimidazolium Bromide Ionic Liquid in Zebrafish Livers

The present study investigated the toxic effects of 1‐butyl‐3‐methylimidazolium bromide ([C₄mim]Br) in zebrafish livers after exposure to 5–40 mg/L of [C₄mim]Br on days 7, 14, 21, and 28. The results showed that low levels of [C₄mim]Br exposure activated the superoxide dismutase (SOD) activity during early periods of exposure. However, high concentrations (20–40 mg/L) of [C₄mim]Br caused the inhibition of SOD, which, accordingly, led to excess reactive oxygen species and malondialdehyde. The present results indicate that [C₄mim]Br causes oxidative stress in the livers of both male and female zebrafish. Additionally, the DNA damage revealed that [C₄mim]Br has a genotoxic effect on zebrafish livers, even when the concentration of [C₄mim]Br is low (5 mg/L). The DNA damage was demonstrated by quantifying the DNA strand breakage.     

Activity profile of defence-related enzymes in rice genotypes (Oryza sativa L.) against rice blast (Magnaporthe oryzae)

The control and infected leaf samples of blast resistant and susceptible rice genotypes were evaluated for activities of defence-related enzymes viz., total phenol content, chitinase, phenylalanine ammonia lyase (PAL), β-glycosidase, antioxidative enzymes, superoxide dismutase, peroxidase and ascorbate peroxidase. The level of total phenol content and the activity profile of chitinase, PAL and β-glycosidase significantly increased in both blast-resistant and susceptible rice genotypes with comparatively higher level induction Tetep, NLR-20104 and Swarnadhan the blast-resistant genotypes. The antioxidative enzymes were comparatively higher in the leaf samples of blast-resistant genotypes recording highest increase in NLR-20104 and KJT-5. The constitutive levels of total phenols and activity of defence-related and antioxidative enzymes in the control leaf samples differed among the genotypes and were even higher in the two blast susceptible genotypes (EK-70 and Chimansal). However, the level of induction as evident from the activity profile differences between control and infected leaf samples suggests higher level of induction was more which is indicative of the induced defence response. The genotype recording maximum induction of defence-related and antioxidative enzymes activity could be useful criteria in screening for blast resistant genotype in rice.     

Cyclodiene organochlorine insecticide-induced alterations in the sulfur-redox cycle in CHO-K1 cells

The effect of the cyclodiene organochlorine pesticides aldrin, dieldrin and endosulfan was assessed on CHO-K1 cultures at fractions of their lethal doses, determined by the neutral red (NRI) incorporation assay (NRI_6.25, NRI_12.5 and NRI₂₅). Glutathione peroxidase, reductase and S-transferase, and total and oxidised glutathione were evaluated along the standard growth curve of the cultures. After a 24-h incubation with each insecticide, glutathione peroxidase incurred a large increase, while glutathione reductase and S-transferase activities were slightly higher than untreated controls. Unlike oxidised glutathione, the content of total glutathione declined significantly after exposure to cyclodiene insecticides. Changes in cell membrane integrity were assessed by the lactate dehydrogenase (LDH) release assay and lipid peroxidation for a wide range of pesticide concentrations. Membrane leakage and peroxide production were significantly enhanced at concentrations of aldrin and as low as 12.5 μg/ml, whereas dieldrin and endosulfan increased membrane fragility at much higher concentrations.     

In Vitro Effects of Calcium Fructoborate on fMLP-stimulated Human Neutrophil Granulocytes

Discovery of naturally occurring boron complexes with organic compounds containing hydroxyl groups, sugars, and polysaccharides, adenosine-5-phosphate, pyridoxine, riboflavin, dehydroascorbic acid, and pyridine nucleotides led to the reassessment of the biochemical role of boron. Boron’s anti-inflammatory actions were claimed but not yet demonstrated. This study investigated the effects of calcium fructoborate (CF) on the human polymorphonuclear neutrophils (PMN) that play a central role in the inflammatory response. Our results demonstrated that CF exposure induced a dose-dependent decrease in cell viability. Treatment of PMN cells, for 24 h, with 22,500 μM CF led to a decrease in cell viability by 61.1%, an inhibition of respiratory burst by 92.9% in the case of fMLP-stimulated cells, a diminution of intracellular level of superoxide anion with 59.3%, and a stimulation of superoxide dismutase activity by 72% in unstimulated PMN cells. Altogether, these results suggest the antioxidant and anti-inflammatory properties of CF.