作保灵(TNA)对水稻的保护作用及作用机理研究

研究了作保灵对水稻的保护作用及对氯嘧磺隆的解毒机理。当土壤中氯嘧磺隆残留量为10μg· kg-1时 ,水稻生长发育受到影响,并随着氯嘧磺隆残留量的增加,对水稻的抑制作用明显增强。作保灵 50 mg· kg-1浸种或 200mg· kg-1叶喷都能缓解氯嘧磺隆对水稻产生的药害。作保灵能明显提高水稻体内谷胱甘肽转移酶(GST)活性,增加谷胱甘肽(GSH)、多酚及脯氨酸含量,诱导氯嘧磺隆与谷胱甘肽、多酚进行轭合,从而对氯嘧磺隆进行解毒。     

天然芸苔素内酯减轻胺苯磺隆对水稻药害的作用

采用土培法在室内测定了不同浓度胺苯磺隆对水稻生长的影响，不同浓度天然芸苔素内酯对胺苯磺隆的解毒效应，以及不同浓度胺苯磺隆处理下天然芸苔素内酯浸种对水稻根生长的影响。结果表明，当天然芸苔素内酯浓度在0.01-0.05mg/L范围内时，可显著缓解1.0μg/kg的胺苯磺隆对水稻的药害，用0.02mg/L的天然芸苔素内酯种可不同程度地缓解0.1-20μg/kg的胺苯磺隆对水稻的药害。     

安全剂R-28725保护玉米免受氯磺隆药害的作用

采用生物测定法研究了安全剂R-28725保护玉米免受除草剂氯磺隆药害的作用.在氯磺隆毒土浓度为2 μg/kg时,使用5mg/kgR-28725浸种处理,玉米根部受到氯磺隆抑制的谷胱甘肽(GSH)含量由空白对照的57.3％恢复至83.4％;玉米叶片中乙酰乳酸合成酶(ALS)活性增加了17.2％;玉米根部的谷胱甘肽-S-转移酶(GST)活性增加了191.8％;GST酶促反应动力学参数Vmax增大102.5％,Km减小40.0％.结果显示:R-28725能够提高氯磺隆处理后玉米中GSH的含量,增加GST和ALS活性,增强了玉米根部GST酶对底物的亲和力,缓解氯磺隆对玉米产生的药害.     

靶标酶在除草剂研究与开发中的作用

大多数除草剂都是通过特殊酶的抑制而产生杀草作用的。根据作用靶标对除草剂进行分类,了解靶标酶的作用机理及特性,对于新型除草剂的设计和杂草抗性的防治能够起到很大的帮助。本文介绍了谷胱甘肽转移酶(GST)、细胞色素P450酶、乙酰乳酸合成酶(ALS)、乙酞辅酶A羧化酶(ACCace)的研究进展。并分别从酶的生理功能、酶学特征、抑制剂作用机理、抑制剂的研究、抗性等方面进行了不同程度的阐述。     

芸苔素内酯保护玉米免受胺苯磺伤害的作用及其机理

采用土培法和田间小区试验法测定了芸苔素内酯(BR)对玉米的保护作用,并对其作用机理进行了初步研究.结果表明:BR的浸种浓度在0.01～0.04mg·L-1范围内,能不同程度地缓解16.0μg·kg-1胺苯磺隆对玉米的药害,BR浓度为0.02mg·L-1时,解毒效果最好.用0.02mg·L-1的BR浸种,能不同程度地缓解2.0～32.0μg·kg-1的胺苯磺隆对玉米生长的抑制,但当胺苯磺隆浓度增加到64.0μg·kg-1时,BR浸种无解毒作用;按15g ai/hm2的剂量施用胺苯磺隆对玉米的减产率达11.8%,用BR 0.02、0.04 mg·L-1浸种处理则减产率分别为0.2%和0.1%;BR提高胺苯磺隆处理的玉米幼苗中ALS活性可能是其保护玉米免受胺苯磺隆伤害的机理之一.     

莎稗磷对水稻生理生化特性的影响

通过盆栽试验,探讨了莎稗磷施药量、施药时期、施药时的水层深度对不同水稻品种生理生化特性的影响。结果表明：在供试水稻品种中施用莎稗磷会导致水稻的叶绿素含量和根系活力降低,诱导水稻体内的GSH含量、GST活性和SOD活性的提高;在同一品种中,随施药量增加,GSH含量、GST活性先升高后降低,而SOD活性持续增加;缓苗后施用莎稗磷,水稻GSH含量、GST活性和SOD活性提高幅度高于缓苗前施药;施药时保持4 cm水层（未没过心叶）对水稻GSH含量、GST活性和SOD活性的提高幅度低于保持8 cm水层施药（没过心叶）。初步明确水稻东农419对莎稗磷的敏感性高于绥粳4号。     

芸苔素内酯保护玉米免受胺苯磺隆伤害的作用及其机理

采用土培法和田间小区试验法测定了芸苔素内酯(BR)对玉米的保护作用,并对其作用机理进行了初步研究。结果表明:BR 的浸种浓度在0.01～0.04mg·L~(-1)范围内,能不同程度地缓解16.0μg·kg~(-1)胺苯磺隆对玉米的药害,BR 浓度为0.02mg·L~(-1)时,解毒效果最好。用0.02mg·L~(-1)的 BR 浸种,能不同程度地缓解2.0～32.0μg·kg~(-1)的胺苯磺隆对玉米生长的抑制,但当胺苯磺隆浓度增加到64.0μg·kg~(-1)时,BR 浸种无解毒作用;按15g ai/hm~2的剂量施用胺苯磺隆对玉米的减产率达11.8％,用BR 0.02、0.04 mg·L~(-1)浸种处理则减产率分别为0.2％和0.1％;BR 提高胺苯磺隆处理的玉米幼苗中 ALS 活性可能是其保护玉米免受胺苯磺隆伤害的机理之一。     

0.136%赤·吲乙·芸苔可湿性粉剂与五氟磺草胺混用对无芒稗和水稻生长的影响

为探究0.136%赤·吲乙·芸苔可湿性粉剂(WP)与除草剂五氟磺草胺分散油悬浮剂(OD)混用对稗草防除效果及对水稻生长的影响,以无芒稗和水稻为研究对象,设置清水对照、0.136%赤·吲乙·芸苔WP、25 g/L五氟磺草胺OD、0.136%赤·吲乙·芸苔WP+25 g/L五氟磺草胺OD混用4个处理,观察药后无芒稗和水稻的生长情况,测定乙酰乳酸合酶(ALS)活性、叶绿素荧光参数及糖代谢和氮代谢等生理指标。结果表明,与25 g/L五氟磺草胺OD单用相比,0.136%赤·吲乙·芸苔WP+25 g/L五氟磺草胺OD混用处理药后第7天,无芒稗的中毒综合指数显著提高13.2%,ALS活性显著降低27.61%;无芒稗的叶绿素荧光参数(Fv/Fm、ETR、qP)、糖代谢和氮代谢指标均显著下降;水稻的ALS活性、糖、氮代谢水平均显著提高。0.136%赤·吲乙·芸苔WP+25 g/L五氟磺草胺OD混用提高了五氟磺草胺对无芒稗光合作用及糖代谢和氮代谢水平的抑制作用,提高了五氟磺草胺对无芒稗的防除效果;并能缓解五氟磺草胺对水稻的胁迫作用,促进水稻生长。     

萘二甲酸酐减轻胺苯磺隆对水稻药害的作用机制

通过在离体和活体条件下萘二甲酸酐（NA）对水稻乙酰乳酸合成酶（ALS）活力的影响,进行NA减轻胺苯磺隆对水稻药害作用机制研究。离体条件下,NA对水稻幼苗ALS的活力影响很小,且未能产奋勇安苯磺隆对ALS活性的抑制作用。活体条件下,NA提高幼苗ALS活力达40％,且抵消胺苯磺隆对ALS活力的抑制作用,说明NA减轻胺苯磺隆对水稻药害的作用机制是NA间接激活靶标酶ALS。     

0.01%芸苔素内酯对小麦经济性状及产量的影响

小麦是我国北方主要粮食作物 ,提高单产是栽培的重要环节 ,增加穗数、每穗粒数和千粒重是获得高产的基础。植物生长调节剂可以增加小麦穗数 ,防止倒伏 ,提高产量 ,在小麦的栽培中起着极其重要的作用。芸苔素内酯是一类重要的植物生长调节剂 ,在小麦栽培中有着广泛的用途。为了更好的使用芸苔素内酯 ,特进行了本次试验 ,现将结果报道如下。1　试验材料及方法试验小麦品种为“鄂恩 1号”,试验田为前茬水稻 ,地势平坦 ,肥力均匀 ,排灌方便。土壤类型为粘性壤土 ,p H值为 6.5 ,有机质含量 1 .9%左右。试验设每 hm2 0 .0 1 %芸苔素内酯 EC 0 .0…     

Effects of indoleacetic acid and kinetin on lipid peroxidation and antioxidant defense in various tissues of rats

This study aims to investigate the effects of indoleacetic acid (IAA) and kinetin (Kn), which are plant growth regulators (PGRs), on antioxidant defense systems [reduced glutathione (GSH), glutathione-S-transferase (GST), catalase (CAT)], and lipid peroxidation level (malondialdehyde, MDA) various tissues of rats. Rats (Sprague-Dawley albino) were exposed to 100 ppm IAA and Kn. One hundred parts per million of PGRs was administered orally to rats ad libitum for 21 days continuously. The PGRs treatments caused different effects on the content of MDA and antioxidant defense system in comparison to those of control rats. According to the results, the subchronic treatments of IAA caused significant decrease in the GSH concentration and CAT activity in erythrocyte. Kn decreased GSH concentration in erythrocyte too. While the MDA concentration in brain was increased significantly by IAA and Kn, Kn decreased significantly brain CAT and GST activity. The liver GST activity was decreased by IAA and Kn. But, liver CAT activity was increased by IAA. On the other hand, while IAA treatment caused a significant decrease kidney GST activity, Kn caused a significant decrease both kidney GST and CAT activity. Also, while heart CAT activity was decreased by IAA, heart GST activity was decreased by both IAA and Kn. Moreover, MDA concentration in heart was increased by Kn treatment. It was concluded that IAA might effect MDA and antioxidant defense on the animals at subchronic treatment.     

三种ALS抑制剂对四类植物ALS的抑制差异

用乙酰乳酸合成酶(ALS)活性测定方法研究了双草醚、KIH-15127、苄嘧磺隆3种ALS抑制剂对水稻、稗草和油菜ALS活性的抑制差异性。体外测定结果表明，不同植物ALS对双草醚和KIH-15127的敏感性差异较大，粳稻、稗草和油菜ALS的敏感性强于籼稻，而这些植物ALS对苄嘧磺隆的敏感性差异很小。体内结果显示，双草醚和KIH-15127对稗草和油菜ALS的抑制作用较强，对粳稻ALS的抑制作用可以恢复；苄嘧磺隆对油菜ALS的抑制作用也较强，但对稗草、水稻ALS基本无抑制作用；3种ALS抑制剂对籼稻ALS抑制作用均较弱。结果表明，不同植物对ALS抑制剂的敏感性存在差异。     

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.     

Effects of carbaryl and azinphos methyl on juvenile rainbow trout (Oncorhynchus mykiss) detoxifying enzymes

In this study, the effects of sublethal exposures to the anticholinesterase insecticides azinphos methyl (AzMe) and carbaryl on the detoxifying responses of juvenile rainbow trout Oncorhynchus mykiss were investigated. Juvenile specimen were exposed to sublethal concentrations of AzMe (2.5 and 5 μg/L) and carbaryl (1 and 3 mg/L) for 24, 48 and 96 h. Carboxylesterase (CbE), catalase (CAT) and glutathione S-transferase (GST) activities as well as reduced glutathione (GSH) and cytochrome P450-1A (CYP1A) levels were monitored in liver and/or kidney. In all exposed groups liver CbE was significantly inhibited. Liver and kidney GSH level was reduced after sublethal exposure to both compounds. Carbaryl induced CAT activity during the first 48 h of exposure, followed by a significant decrease, whereas AzMe continuously decreased CAT activity. GST activity and CYP1A were transiently induced at 24 h by carbaryl exposure (3 mg/L) but sublethal exposure to AzMe did not affect GST activity or CYP1A. Our results show that the O. mykiss detoxifying system are a target for carbaryl and AzMe action, probably affecting redox balance. Although the responses showed similar trends in both organs, they were more important in liver than in kidney. The early inhibitory effect in CAT activity and GSH content produced by AzMe may be associated with a high degree of oxidative stress. Early induction of CYP1A, GST and CAT by carbaryl followed by enzyme inhibition suggests a milder or delayed oxidative stress, revealing differences between both pesticides metabolization. CbE inhibition is a good biomarker for AzMe and carbaryl exposure.     

The role of glutathione S-transferases in the detoxification of some organophosphorus insecticides in larvae and pupae of the yellow mealworm,Tenebrio molitor (Coleoptera: Tenebrionidae)

The correlation between the natural levels of glutathione S-transferase (GST) and the tolerance to the organophosphorus insecticides parathion-methyl and paraoxon-methyl, as well as the interaction of affinity-purified enzyme and the insecticides were investigated in order to collect further information on the role of the glutathione S-transferase system as a mechanism of defence against insecticides in insects. The studies were carried out on the larvae and pupae of the coleopteran Tenebrio molitor L, which exhibit varying natural levels of GST activity. Stage-dependent susceptibility of the insect against insecticides was observed during the first 24 h. However, 48 h after treatment, the KD₅₀ value increased significantly due to the recovery of some individuals. Simultaneous injection of insecticide with compounds which inhibit GST activity in vitro caused an alteration in susceptibility of insects 24 or 48 h post-treatment, depending on stage and insecticide used. Inhibition studies combined with competitive fluorescence spectroscopy revealed that the insecticides probably bind to the active site of the enzyme, thus inhibiting its activity towards 1-chloro-2,4-dinitrobenzene in a competitive manner. High-performance liquid chromatography and gas chromatography revealed that T molitor GST catalyses the conjugation of the insecticides studied to a reduced form of glutathione (GSH). From the above experimental results, it is considered that GST offers a protection against the organophosphorus insecticides studied by active site binding and subsequent conjugation with GSH. © 2001 Society of Chemical Industry     

Effect of 4-chloro-2-methylphenoxyacetic acid and 2,4-dimethylphenol on human erythrocytes

The effects of exposure of human erythrocytes to different concentrations of 4-chloro-2-methylphenoxyacetic acid (MCPA) and its metabolite—2,4-dimethylphenol (2,4-DMP) were studied. The investigations concerned mainly the content of glutathione (GSH and GSSG), glutathione peroxidase (GSH-Px), glutathione transferase (GST), and the level of adenine energy charge (AEC). Reactive oxygen species (ROS) such as hydroxyl radical, superoxide anion, hydrogen peroxide, and nitric oxide are produced during normal processes in the cell. Under normal conditions, antioxidant systems of the cell minimize damage caused by ROS. When ROS generation increases to an extent that it overcomes the cellular antioxidant systems, the result is oxidative stress. We observed that MCPA and 2,4-DMP decreased the level of GSH in erythrocytes in comparison with control. MCPA did not affect glutathione peroxidase and glutathione transferase activity, while 2,4-DMP increased their activity. 2,4-DMP decreased the level of ATP and increased the content of ADP and AMP, leading to the fall of the level of AEC. MCPA and 2,4-DMP transform hemoglobin into methemoglobin, thus preventing oxygen transport. Comparison of the toxicity of MCPA and 2,4-DMP revealed that the most prominent changes occurred in human erythrocytes incubated with 2,4-DMP.     

Protective effects of Nigella sativa oil on propoxur-induced toxicity and oxidative stress in rat brain regions

Propoxur (PPr) is a widely used broad spectrum carbamate insecticide mainly used to control household pests. Because of the widespread use of pesticides for domestic and industrial applications, evaluation of their neurotoxic effects is of major concern to public health. The aim of the present study was to evaluate the possible protective effects of Nigella sativa oil (NSO), an antioxidant agent, against PPr-induced toxicity and oxidative stress in different brain regions of rats including cerebellum, cortex and hippocampus. In the present study, 32 male Sprague-Dawley rats were used and divided into four equal groups. Group 1 was allocated as the control group. Groups 2-4 were orally administered 1 ml/kg/bw/day NSO, 8.51 mg/kg/bw/day PPr or NSO plus PPr, respectively, for 30 days. Lipid peroxidation (LPO), protein carbonyl content (PCC) and acetylcholine esterase activity (AChE) were determined. Enzymatic antioxidant activities [superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione-S-transferase (GST)] and non-enzymatic antioxidants [reduced glutathione (GSH)] were determined. PPr treatment significantly increased the levels of LPO, PCC and oxidized glutathione (GSSG) in brain regions. On the contrary, levels of GSH and the activities of SOD, CAT, GSH-Px, GST and AChE were significantly decreased. NSO treatment to PPr intoxicated rats restored such biochemical parameters to within control levels except GST activity, emphasizing its antioxidant role. We conclude that NSO significantly reduces PPr-induced toxicity and oxidative stress in rat brain regions via a free radicals scavenging mechanism.