褐飞虱共生菌抗感吡虫啉菌株体内抗氧化酶活性的比较

在含不同浓度吡虫啉的综合马铃薯葡萄糖琼脂液体培养基中接种抗感吡虫啉褐飞虱共生菌菌株且培养2～6天后,通过测定抗吡虫啉菌株和敏感菌株的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)等活性,阐明抗感菌株在吡虫啉胁迫下体内抗氧化酶活性的变化.结果显示,抗吡虫啉菌株和敏感菌株三种抗氧化酶活性差异明显不同,抗性菌株的SOD、POD活性(极)显著高于敏感菌株,其中抗性菌株SOD活性比敏感菌株提高了45.89％～222.53％;抗性菌株的CAT活性与敏感菌株差异无明显规律性.说明褐飞虱共生菌对吡虫啉的抗药性与其体内SOD和POD的活性增强有关.     

Role of hydrogen peroxide and antioxidative enzymes in Pinus tabulaeformis seedlings inoculated with Amanita vaginata and/or Rhizoctonia solani

The ectomycorrhizal fungus Amanita vaginata can control damping off (Rhizoctonia solani) and promote growth of Pinus tabulaeformis seedlings. The aim of this study was to investigate whether reactive oxygen species and antioxidative enzymes play a role in preventing damping off in ectomycorrhizal roots. Two months after P. tabulaeformis roots were inoculated with A. vaginata, the roots were inoculated with R. solani. During the early stages (2?C96?h) of R. solani infection, the quantity and localisation of hydrogen peroxide and the activities of superoxide dismutase and catalase were evaluated. A burst of hydrogen peroxide occurred in ectomycorrhizal roots and in non-ectomycorrhizal roots when attacked by R. solani. In ectomycorrhizal roots, hydrogen peroxide production peaked 12?h after R. solani inoculation, which coincided with an increase in the activity of superoxide dismutase and catalase, whereas in non-ectomycorrhizal roots, hydrogen peroxide production peaked 24?h after R. solani inoculation and did not coincide with changes in superoxide dismutase or catalase activity. The imbalanced activities of superoxide dismutase and catalase might cause excessive accumulation of hydrogen peroxide and consequent damage to cell walls. Electron microscopy revealed that there was a positive correlation between hydrogen peroxide levels and the number of amyloplasts, with seedlings inoculated with A. vaginata and/or R. solani showing higher levels. These results indicated that A. vaginata inoculation enhanced damping off resistance and stimulated seedling growth, which may be due to the activation of a burst of hydrogen peroxide and its scavenging enzymes and the production of biochemical substances such as amyloplasts.     

Subacute chlorpyrifos-induced oxidative stress in rat erythrocytes and the protective effects of catechin and quercetin

This study examined the effects of chlorpyrifos in the rat erythrocyte antioxidant system and evaluated the ameliorating effects of catechin and quercetin on the oxidative damage induced by chlorpyrifos. Sexually mature male Wistar rats were given chlorpyrifos (5.4 mg/kg, 1/25 of the oral LD₅₀), catechin (20 mg/kg), quercetin (20 mg/kg), catechin plus chlorpyrifos, and quercetin plus chlorpyrifos daily via gavage for four weeks. No statistical differences were found in the catechin-only and quercetin-only groups compared with the control group. By the end of the fourth week, chlorpyrifos alone increased the levels of malondialdehyde (MDA) and decreased superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities compared with the control group in rat erythrocytes. In the catechin-plus-chlorpyrifos and quercetin-plus-chlorpyrifos groups, there were statistically significantly decreased MDA levels and increased SOD, CAT, and GPx activities compared with the chlorpyrifos-only group. Thus, it appears that catechin and quercetin ameliorate chlorpyrifos-induced oxidative stress in rat erythrocytes in vivo.     

Lipid peroxidation and oxidative stress in rat erythrocytes induced by chlorpyrifos and the protective effect of zinc

Male and female rats were orally administered chlorpyrifos at a dose of 6.75 mg kg⁻¹ body weight for 28 consecutive days. An additional chlorpyrifos group received zinc (227 mg l⁻¹) in drinking water throughout the experimental duration. Two groups more served as controls; one received water only and the other received zinc in drinking water. Administration of chlorpyrifos resulted in a significant increase in lipid peroxidation (LPO) level and significant decrease in the activities of superoxide dismutase (SOD), glutathione-s-transferase (GST), catalase (CAT) and acetylcholinesterase (AChE) in erythrocytes of male and female rats. In contrast, zinc-chlorpyrifos treatment showed insignificant differences (p ? 0.05-0.01), compared to control results, regarding LPO, SOD, GST and CAT. In case of AChE, supplementation of zinc showed little alteration in the activity of this enzyme in the rats treated with chlorpyrifos. It can deduce that chlorpyrifos induced oxidative stress and lipid peroxidation in erythrocytes of male and female rats. The overall results reveal the pronounced ameliorating effect of zinc in chlorpyrifos-intoxicated rats and variation in the response of male and female animals regarding alteration in the level of some biochemical parameters and LPO.     

In vivo chlorpyrifos induced oxidative stress: Attenuation by antioxidant vitamins

Chlorpyrifos (O,O′-diethyl O-3,5,6-trichloro-2-pyridyl phosphorothionate, CPF) exposure in rats causes elevation in the levels of thiobarbituric acid reactive substances (TBARS) and inhibition of acetylcholinesterase (AChE), superoxide dismutase (SOD), catalase (CAT), and glucose-6-phosphate dehydrogenase (G6PDH) activities in the liver, kidney, spleen, and brain of rats. The sublethal exposure of CPF also causes decrease in the levels of reduced glutathione (GSH) and consequent increase in oxidized glutathione (GSSG) levels, resulting in a significant decrease in GSH/GSSG ratio in all the rat tissues tested. These results clearly indicate that CPF exposure causes oxidative stress in rat tissues. However, CPF exposure to rats fed with antioxidant vitamins (vitamin A, E, and C) for 1 month, prevented derangement of these antioxidant parameters. The accumulation of TBARS was also not seen in tissues of rats fed with antioxidant vitamins on CPF exposure. AChE activity, which is sensitive to OP pesticides, was also not significantly inhibited in these rats on CPF exposure. The present findings clearly show that oral intake of a mixture of vitamin A, E, and C, protects the rats from CPF induced oxidative stress and suggesting that this treatment alleviates the toxicity of this pesticide.     

Effects of an impurity on malathion and its structural analog on rat liver carboxylesterases and erythrocyte esterases

The inhibitory effects on liver microsomal carboxylesterases and erythrocyte membrane esterases produced by an impurity of malathion was investigated. Treatment of rats with an impurity of malathion, O,O,S-trimethyl phosphorothioate (OOS-Me), and its structural analog O,O-dimethyl S-ethyl phosphorothioate (OOS-Et) inhibited liver microsomal malathion and phenthoate carboxylesterases. The inhibition lasted for at least 7 days following a single oral administration of OOS-Me. These treatments inhibited acetylcholinesterase (AChE) and (Na⁺ + K⁺)-dependent ATPase of erythrocyte membranes which persisted at least 3 days. OOS-Et was a more potent inhibitor of all the esterases examined than OOS-Me. Pretreatment of rats with a metabolic inducer, phenobarbital, or a metabolic inhibitor, piperonyl butoxide, had no effect on such inhibitory effects on liver microsomal carboxylesterases produced by OOS-Me or OOS-Et.     

Overproduction of reactive oxygen species involved in the pathogenicity of Fusarium in potato tubers

Differences in virulence between Fusarium sulphureum and Fusarium sambucinum were compared. Changes in reactive oxygen species production and metabolism in inoculated slices of potato tubers were also compared. The result showed that Fusarium infection induced significant production of ROS, lipid peroxidation and loss of cell membrane integrity, but low activity of superoxide dismutase (SOD) and ascorbate peroxidase (APX). Compared to F. sambucinum, F. sulphureum led larger lesion diameters on potato tubers and slices. It resulted in more superoxide anion ($O_2^{-}$) and earlier peak of hydrogen peroxide (H₂O₂), but lower activity of catalase (CAT) and APX, and accompanied with higher malondialdehyde (MDA) content and lower cell membrane integrity. These findings suggested that overproduction of ROS involved in the pathogenicity of Fusarium in potato tubers.     

Allelochemical ethyl 2-methyl acetoacetate (EMA) induces oxidative damage and antioxidant responses in Phaeodactylum tricornutum

Ethyl 2-methyl acetoacetate (EMA) is a novel allelochemical exhibiting inhibitory effects on the growth of marine unicellular alga Phaeodactylum tricornutum (P. tricornutum). Oxidative damage and antioxidant responses in P. tricornutum were investigated to elucidate the mechanism involved in EMA inhibition on algal growth. The increase in reactive oxygen species (ROS) levels and malondialdehyde (MDA) contents following exposure to EMA suggested that alga was suffered from oxidative stress and severely damaged. The decrease in cell activity and cellular inclusions suggested that cell growth was greatly inhibited. The activities of the antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxide (GSH-PX) and glutathione S-transferase (GST) increased with the exposure concentration and decreased with the prolongation of exposure time. Cellular ascorbic acid (AsA) and reduced glutathione (GSH) systems were also involved in resisting oxidative stress of EMA by altering the composition of AsA and GSH pools. EMA exposure increased the contents of AsA, GSH, dehydroascorbate (DAsA) and glutathione (GSSG). However, the regeneration rate of AsA/DAsA did not change obviously between treatments and the control, while that of GSH/GSSG decreased significantly under 14 mmol/L EMA exposure on the 3rd day. These results showed that EMA-induced oxidative damage might be responsible for EMA inhibition on P. tricornutum growth and cellular antioxidant enzymes and non-enzymatic antioxidants were improved to counteract the oxidative stress.     

冠菌素诱导甘蓝幼苗抗黑腐病及其机理初步研究

以甘蓝 Brassica oleracea L.感病品种"庆丰"为材料,通过叶面喷施冠菌素(coronatine,COR)和人工接种黑腐病菌——野油菜黄单胞菌野油菜致病变种(Xanthomonas campestris pv.campestris)的方法,研究了COR诱导甘蓝幼苗抗黑腐病的效果及其生理生化机制。结果表明, COR在质量浓度为0.01、0.1和1.0 mg/L下均具有诱导甘蓝幼苗抗黑腐病的效果,其中1.0 mg/L 处理的病情指数为38.2,诱抗率为43.7%,诱导抗病效果最好。与对照相比,随着COR质量浓度的提高,叶片中过氧化氢酶(CAT)活性和超氧阴离子(O2-)产生的速率明显增加,而过氧化物酶(POD)的活性增加不明显,超氧化物歧化酶(SOD)活性和丙二醛(MDA)的含量明显下降。表明COR具有诱导甘蓝幼苗抗黑腐病的作用,而这种作用可能与COR能调控甘蓝幼苗中抗氧化酶活性、提高O2-产生速率以及降低MDA的含量相关。     

Bentazone and bromoxynil induce H and H2O2 accumulation, and inhibit photosynthetic O2 evolution in Synechococcouselongatus PCC7942

Using a unicellular cyanobacterium, Synechococcouselongatus PCC7942, we have shown that cytosolic acidification, O₂⁻; H₂O₂ production and photosystem II-inactivation are the causes of cell death from bentazone/bromoxynil incubations. Butyric acid evoked solely pH lowering response and yet inhibited PS II activity indicating that herbicide-caused acidification is sufficient to kill the cyanobacterial cells, but other factors like excess H₂O₂ production due to an imbalance in the peroxide sequestration machinery might be contributory. While the activities of superoxide dismutase and pyrogallol peroxidase increased consequent to herbicide incubations and displayed oligomeric states with mobility shift, catalase and glutathione peroxidase though present remained insensitive.     

Protective effect of vitamin C against chlorpyrifos oxidative stress in male mice

Pesticides may induce oxidative stress leading to generate free radicals and alternate antioxidant or oxygen free radical scavenging enzyme system. This study was conducted to investigate the acute toxicity of chlorpyrifos toward male mice and the oxidative stress of the sub-lethal dose (1/10 LD₅₀) on the lipid peroxidation level (LPO), reduced glutathione content (GSH) and antioxidant enzymes; catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), glucose-6-phosphate dehydrogenase (G6PD), and glutathione-S-transferase (GST) activities. Also, the protective effects of vitamin C (200 mg/kg body weight, bw) 30 min before or after administration of chlorpyrifos were investigated. The results demonstrated that the LD₅₀ value of chlorpyrifos was 134.95 mg/kg bw. The oral administration of 13.495 mg/kg chlorpyrifos significantly caused elevation in LPO level and the activities of antioxidant enzymes including CAT, SOD and GST. However, GPx activity remained unchanged, while the level of GSH and G6PD activity were decreased. Vitamin C treatment to chlorpyrifos intoxicated mice decreased LPO level and GST activity, normalized CAT, SOD and G6PD activities, while GSH content was increased. We conclude that vitamin C significantly reduces chlorpyrifos-induced oxidative stress in mice liver and the protective effect of the pre-treatment with vitamin C is better than the post-treatment.     

In vitro metabolism of diazinon and etrimfos by corn plant preparations

Homogenates prepared from excised roots or stems and leaves of corn seedlings metabolize up to 72% of [¹⁴C]pyrimidinyl-labeled diazinon (O,O-diethyl-O-[6-methyl-2-(1-methylethyl)-4-pyrimidinyl]phosphorothioate) to 6-methyl-2-(1-methylethyl)-4-hydroxypyrimidine and one unidentified metabolite. Six-day-old corn seedling homogenate had the highest degradative activity. The optimum pH for activity was 6.0 and the activity was found to reside in the cytosol. Etrimfos [O,O-dimethyl-O-(6-ethyl-4-pyrimidinyl)phosphorothioate] was not susceptible to degradation by the corn plant preparation.     

Oxidative parameters of Rhamdia quelen in response to commercial herbicide containing clomazone and recovery pattern

In this study, fish Rhamdia quelen, were exposed to different concentrations of herbicide clomazone: 0.0 (control), 0.45 and 0.91 mg L⁻¹. After exposure for 8 days to herbicide, fish were transferred to clean water for a recovery period (8 days). Oxidative stress indicators such as thiobarbituric acid reactive substances (TBARS) levels and protein carbonyl content, as well as antioxidant defenses, such as catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), ascorbic acid and non-protein thiols levels were studied, using the liver, brain and muscle tissues. Herbicide exposure increased TBARS in muscle and in liver at higher concentration. In liver protein carbonylation increased and catalase activity did not change in fish exposed to herbicide. SOD enhanced in liver at concentration of 0.91 mg L⁻¹. GST, ascorbic acid and non-protein thiols levels increase at both concentrations. At the end of the recovery period the most of the parameters recovered whereas GST and ascorbic acid remain elevated. The present study demonstrates the occurrence of disorders in antioxidant parameters and importance in the assessment of the potential risk of herbicides as clomazone on fish species.     

Evaluation of etoxazole toxicity in the liver of Oreochromis niloticus

The effects of etoxazole were evaluated in freshwater fish Oreochromis niloticus from five different sublethal etoxazole concentrations in order to study the biochemical response, photometrically. No changes were observed in the activities of antioxidant enzymes such as superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), and glutathione peroxidase (GPx, EC 1.11.1.9). These were measured in liver after 1, 7, and 15 days of exposure to sublethal concentrations of 0.2, 0.4, 0.6, 0.8, and 1% of field application rate (134.75 ppm). This study also investigated the levels of neurotoxic effects by the determination of acetylcholine esterase (AChE EC 3.1.1.7) and sodium-potassium adenosine 5^′-triphosphatase (Na⁺K⁺-ATPase, EC 3.6.3.9) activities. The exposure of fish led to sharp depletion in AChE activity while there is no significant alteration in Na⁺K⁺-ATPase activity. Up to 80% decreases were observed in the AChE activity. Since no difference was found in the activity of glutamate-pyruvate transaminase (GPT, EC 2.6.1.2), etoxazole did not show hepatotoxic effect. The results of the present study show that increase in the malondialdehyde (MDA) contents and decrease in the AChE activity can be used as biomarkers for monitoring toxicity in etoxazole exposure.     

寡聚半乳糖醛酸诱导烟草抗烟草花叶病毒研究初探

用寡聚半乳糖醛酸诱导烟草抗烟草花叶病毒,田间和温室试验结果表明,寡聚半乳糖醛酸50μg/mL的诱抗效果最好,对烟草花叶病毒引起的枯斑的抑制率为64.4%。寡聚半乳糖醛酸可以诱导烟草植株抗性酶超氧化物歧化酶和过氧化氢酶活性的升高。     

Jasmonic and salicylic acid-induced resistance in sorghum against the stem borer Chilo partellus

Induced resistance was studied in three sorghum genotypes (IS2205, ICSV1 and ICSV700) against Chilo partellus (Swinhoe) (Lepidoptera; Pyralidae) infestation and jasmonic acid (JA) and salicylic acid (SA) application. The activity of plant defensive enzymes [peroxidase (POD), polyphenol oxidase (PPO), superoxide dismutase (SOD), and catalase (CAT)], and the amounts of total phenols, hydrogen peroxide (H₂O₂), malondialdehyde (MDA), and proteins were recorded at 6 days after infestation. The induction of enzyme activities and the amounts of secondary metabolites varied among the genotypes and treatments. The genotype IS2205 showed a stronger effect than that of ICSV1 or ICSV 700. Treatment with JA followed by insect infestation induced greater levels of enzymes and secondary metabolites. The results suggest that JA induces greater levels of resistance components in sorghum plants against insect pests. Thus, pretreatment of plants with elicitors including JA and SA could provide a greater opportunity for plant defense against herbivores.     

Indoxacarb resistance in the house fly, Musca domestica

Indoxacarb (DPX-MP062) is a recently introduced oxadiazine insecticide with activity against a wide range of pests, including house flies. It is metabolically decarbomethoxylated to DCJW. Selection of field collected house flies with indoxacarb produced a New York indoxacarb-resistant (NYINDR) strain with >118-fold resistance after three generations. Resistance in NYINDR could be partially overcome with the P450 inhibitor piperonyl butoxide (PBO), but the synergists diethyl maleate and S,S,S-tributyl phosphorothioate did not alter expression of the resistance, suggesting P450 monooxygenases, but not esterases or glutathione S-transferases are involved in the indoxacarb resistance. Conversely, the NYINDR strain showed only 3.2-fold resistance to DCJW, and this resistance could be suppressed with PBO. Only limited levels of cross-resistance were detected to pyrethroid, organophosphate, carbamate or chlorinated hydrocarbon insecticides in NYINDR. Indoxacarb resistance in the NYINDR strain was inherited primarily as a completely recessive trait. Analysis of the phenotypes vs. mortality data revealed that the major factor for indoxacarb resistance is located on autosome 4 with a minor factor on autosome 3. It appears these genes have not previously been associated with insecticide resistance.     

Resistance to chlorpyrifos and lambda-cyhalothrin along with detoxifying enzyme activities in field-collected female populations of European red mite

The levels of susceptibility of populations of the European red mite Panonychus ulmi (Koch) (Acarina: Tetranychidae) collected from apple orchards in the Bursa region of Turkey to the insecticides chlorpyrifos and lambda-cyhalothrin, were determined by a petri leaf disk—Potter spray tower method. When compared with the susceptible population, resistance ratios at the LC₅₀ level ranged from 6.0- to 35.6-fold, and from 0.7- to 5.7-fold for chlorpyrifos and lambda-cyhalothrin, respectively. Kinetic parameters of general esterase activity with α-naphthyl acetate as substrate indicated that an increased activity was present in the resistant populations compared with the susceptible populations. In these strains, 1.5- and 2.2-fold higher Glutathione S-transferase (GST) activity was also detected with the substrate 1-chloro-2,4-dinitrobenzene. General esterase activity gel profiles of these populations were studied by native polyacrylamide gel electrophoresis, but no relationship between resistance ratios and band patterns was detected. The results of this study document a decreased efficacy of chlorpyrifos and lambda-cyhalothrin in field populations of P. ulmi in Turkey, possibly linked to altered activities of esterases and GST.     

Residues of chlorpyrifos in various crops II. Residues after field treatments

Five agricultural crops were treated with OO-diethyl O-(3,5,6-trichloro-2-pyridyl) phosphorothioate (chlorpyrifos) granular or emulsifiable concentrate formulations at dosages from 0.5 to 6.0 kg (a.i.)/ha and at different periods before harvest. Chlorpyrifos residues were determined by gas chromatography after extraction and sweep co-distillation clean-up. Low residue levels were found. The average values in lettuce were 0.046 and 0.070 part/million, in sugar beet leaves 0.037 to 0.128 part/million and roots <0.005 to 0.038 part/million; no chlorpyrifos was detected in carrots, potatoes and cured tobacco leaves at the limit of the method (0.005 part/million).