机械伤害和茉莉酸对豌豆幼苗膜脂过氧化的影响

 切割后离体芽苗极易受病菌侵染而发生腐烂变质，严重影响着当前芽菜采后运输和销售。为此,本试验以豌豆芽苗为试材,研究了机械伤害和外施不同浓度（±）茉莉酸（JA）处理对豌豆幼苗膜脂过氧化的影响。结果表明，伤害和1～100 μmol·L-1 JA处理可以显著提高苯丙氨酸解氨酶（PAL）和多酚氧化酶（PPO）活性，同时使活性氧代谢加强，O2-·产生速率和H2O2含量迅速增加，相应的抗氧化酶（SOD、CAT、APX、POD）活性提高。适宜浓度JA（1～10 μmol·L-1）处理可有效诱导防御反应产生，同时，通过提高抗氧化酶活性使膜脂过氧化程度减轻；高浓度JA（100 μmol·L-1）处理造成植物活性氧代谢失调，膜脂过氧化加剧。综合分析认为，10 μmol·L-1JA是诱导豌豆幼苗防御反应产生的适宜处理浓度。     

油桃裂果与膜脂过氧化的关系

以华光油桃为试材，研究了油桃裂果与果实生长发育过程中超氧物自由基积累和膜脂过氧化的关系。结果表明：果实着色期，果实内的超氧物自由基积累，SOD活性因受抑制而下降，MDA含量上升，细胞膜受伤害而透性增大，此时为裂果最严重时期；随后裂果率下降，SOD活性上升，MDA含量下降，膜透性降低，细胞逐渐修复；在接近采收时SOD活性下降，MDA含量再次上升。这除和成熟有关外还与因降雨、灌溉等引起的裂果有关。果实发育过程中SOD活性与MDA含量、细胞膜透性呈负相关，SOD活性高的果实不易裂果。     

茶多酚和L-EGCG的抗烟致脂质过氧化作用

从茶叶中提取的天然多酚类化合物茶多酚和L-表没食子儿茶素没食子酸酯(L-EGCG)对由香烟气相物质诱发的大鼠肺细胞的脂质过氧化有很强的抑制作用,且复合体茶多酚及其主要单体L-EGCG抑制效果接近,同时两者对超氧阴离子自由基和羟自由基都有十分明显的清除作用,表明茶多酚与L-EGCG的抗脂质过氧化机理之一是有效地清除了脂质过氧化的启动子氧自由基.     

Biochemical and histopathological studies to assess chronic toxicity of triazophos in blood, liver and brain tissue of rats

Triazophos, O,O-diethyl-1-H-1,2,4-triazol-3-yl phosphorothioate, (TZ) is an organophosphorus pesticide which is extensively used in agriculture for controlling insect pests. Except a FAO/WHO report no study has investigated its short-term toxicity with respect to its potential to cause biochemical and histopathological alterations. The present study was designed to identify the effect of TZ at different doses (1.64, 3.2 and 8.2 mg/kg) on the oxidative stress parameters in blood as well as organs involved in xenobiotic metabolism (liver and brain) following chronic exposure for 90 days. Moreover, the study also delineates the effect of TZ on the histo-architecture of these organs. The results indicated a dose dependent induction (p < 0.001) of oxidative stress, as evident by increased malondialdehyde (MDA) level and compromised antioxidant defense including glutathione S transferase (GST) activity, glutathione (GSH) content and ferric reducing ability of plasma (FRAP) in blood, and increased MDA level with concomitantly decreased GSH content in tissues, following chronic exposure to TZ. The ratio of MDA: FRAP in blood was found to be increased following chronic exposure to TZ and may serve as a suitable indicator of severity of oxidative damage. Onset of such biochemical alterations is one of the early adaptive responses to TZ exposure which leads to histopathological alterations in terms of diffuse fatty changes expanding from mid-zonal area to whole lobule in liver. However, increased oxidative stress did not bring any morphological alteration in brain. The present study concludes that induction of oxidative stress, leading to subsequent histopathological alterations in liver, is an important mechanism underlying the TZ induced chronic toxicity.     

Exogenously applied hexaconazole ameliorates salinity stress by inducing an antioxidant defense system in Brassica napus L. plants

The ability of hexaconazole (HEX) to ameliorate salinity stress was studied in canola plants (Brassica napus L.). Canola seedlings were subjected to sodium chloride (NaCl) treatment. A treatment with 200 mM NaCl reduced growth parameters, chlorophyll content and protein content as well as increased the proline (Pro) content in canola plants. In addition, NaCl stress increased the endogenous, nonenzymatic antioxidants and the activity of antioxidant enzymes, such as peroxidase (POX; EC 1.11.1.7), superoxide dismutase (SOD; EC 1.15.1.1) and catalase (CAT; EC 1.11.1.6). When these plants were treated with a combination of NaCl and 50 mg L⁻¹ HEX, the inhibitory effects of NaCl stress were decreased by increasing the root growth, shoot growth, dry weight (DW), chlorophyll content, protein content and antioxidant enzyme activity by ameliorating the salinity injury. These results suggested that HEX has an important role in the enhancement of plant antioxidant systems and resistance to salinity in canola plants.     

Using lipid analysis and hyphal length to quantify AM and saprotrophic fungal abundance along a soil chronosequence

We evaluate the use of signature fatty acids and direct hyphal counts as tools to detect and quantify arbuscular mycorrhizal (AM) and saprotrophic fungal (SF) biomass in three Hawaiian soils along a natural soil fertility gradient. Phospholipids16:1ω5c and 18:2ω6,9c were used as an index of AM and saprotrophic fungal biomass, respectively. Both phospholipid analysis and hyphal length indicated that the biomass of AMF was greatest at the highest fertility site, and lowest where phosphorus limits plant growth. Saprotrophic fungal biomass did not vary. Hyphal length counts appeared to under-estimate SF abundance, while the phospholipid AMF:SF ratio was in line with expectations. This study indicates that phospholipids may be a valuable and reliable tool for studying the abundance, distribution, and interactions between AM and saprotrophic fungi in soil.     

Glutathione Peroxidase Activity and Erythrocyte Lipid Peroxidation as Indices of Selenium and Vitamin E Status in Young Pigs

A randomized, blocked 2³ factorial experiment was conducted with 48 pigs from sows fed a diet low in selenium and vitamin E. From 3 to 12 weeks of age the piglets were kept in single pens and fed a basic diet consisting mostly of barley, dried skim milk, soybean meal and dried yeast, and containing 55 µg selenium and 3 mg vitamin E per kg. The treatment factors — i.e. feed supplements — were 2 levels of Se (nil, 60 µg/kg), 2 levels of vitamin E (nil, 50 mg/kg), and 2 levels of the feed antioxidant ethoxyquin (nil, 150 mg/kg). Blood samples, collected at termination of the experiment, were examined for glutathione peroxidase activity (GSH-Px) and resistance against erythrocyte lipid peroxidation (ELP) to evaluate Se and vitamin E status, respectively. Analysis of variance showed the GSH-Px activity to be litter-dependent (P < 0.001) and influenced by selenium supplementation (P < 0.001) but not by the other supplements or by interactions between supplements. Resistance against ELP was influenced only by vitamin E supplementation (P < 0.001). GSH-Px and ELP thus seem to be valuable and simple methods for evaluating, respectively, Se status and vitamin E status in growing pigs.     

Effect of Dietary Fat Quality and Vitamin E on the Antioxidant Potential of Pigs

A randomized blocked factorial experiment was conducted with 90 young pigs. From 4 to 11 weeks of age the pigs were kept in individual pens and fed a selenium supplemented basal diet consisting mostly of propionic acid treated barley, soybean meal and dried skim milk, and containing < 0.5 mg vitamin E per kg. The treatment factors during this period were 3 dietary levels of added vitamin E (nil, 10 and 30 mg/kg) and a 6 % supplement of fresh or oxidized fat (2/3 lard and 1/3 herring oil). From 11 weeks of age until slaughter at 90 kg the pigs received the vitamin E supplements but no fat or dried skim milk. The basal diet for this later experimental period was based on untreated dry barley. Blood samples collected during the period of investigation were examined for vitamin E and for resistance against erythrocyte lipid peroxidation (ELP) in order to evaluate the antioxidant status.Analysis of variance and Student’s t-test on least squares means showed the ELP to be influenced independently by the vitamin E supplement and, during the fat feeding period, by the quality of the fat supplement, with the highest peroxidation resistance (low ELP) in the groups fed fresh fat and a high level of vitamin E. Blood vitamin E level was only influenced — positively — by the vitamin E supplement although variations in the feed vitamin E level below 10–15 mg vitamin E per kg did not result in corresponding variations in measurable blood vitamin E concentrations. In the same low range of vitamin E in the feed there was a statistically significant difference in ELP values between the different vitamin E treatment groups. No clinical manifestations of selenium-vitamin E deficiency were observed in the pigs.The ELP and the plasma vitamin E levels observed would seem to suggest that a total of 15 mg vitamin E per kg barley-based feed will not always be sufficient for growing pigs.     

水分亏缺条件下草莓幼苗几个水分生理指标的变化

在离体脱水和不同浓度蔗糖溶液培养条件下,对草莓幼苗的脂质过氧化作用产物丙二醛、过氧化物歧化酶、细胞膜相对透性和组织相对含水量的变化及其相互关系进行研究。结果表明:随着组织相对含水量降低,丙二醛含量增高,细胞膜相对透性增大;丙二醛含量和组织相对含水量之间呈负相关;r新茎=0.89(HS),r叶片=0.75(HS),组织细胞膜相对透性随着丙二醛含量的增高而增大;在离体条件下过氧化物歧化酶对丙二醛含量增高有一定抑制作用。