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1.
The relationship between glutathione S-transferase activity toward 3,4-dichloronitrobenzene and O-alkyl or O-aryl conjugation of diazinon was investigated in eight strains of house flies. No significant difference was found in the amount of O-aryl conjugation. In contrast, house flies which had higher glutathione S-transferase activity toward 3,4-dichloronitrobenzene also had higher O-alkyl conjugating activity toward diazinon. The glutathione S-transferase(s) in phenobarbital-pretreated flies degraded diazinon faster than those in the nontreated ones. The present results showed that the formation of the O-alkyl conjugate was enhanced by phenobarbital pretreatment, while the formation of the O-aryl conjugate was not affected by induction. Based on these findings, it would appear that one of the multiple forms of glutathione S-transferase is specifically induced and responsible for the increase in O-alkyl conjugation. 相似文献
2.
Orally administered [1-14C]ethyl paraoxon, O,O-diethyl-O-p-nitrophenyl phosphate, is readily absorbed from the gastrointestinal tract of male albino rats. Radioactivity is essentially eliminated in 72 hr by excretion into urine and feces and by expiration as 14CO2. Compounds with radioactivity in the urine are tentatively identified as diethyl phosphoric acid, desethyl paraoxon, ethanol, metabolites conjugated with amino acids, and paraoxon; the first compound is the predominant radioactive metabolite. Intraperitoneally injected phenobarbital, DDT, dieldrin, and endrin are inducers of microsomal enzymes that degrade paraoxon. The aryl phosphate-cleaving activity in vitro is not dependent on the addition of NADPH. O-Dealkylation of paraoxon is catalyzed by microsomal enzymes that require NADPH and oxygen and are inhibited by carbon monoxide. Microsomal enzymes from rats pretreated with enzyme inducers give an increased rate of O-dealkylation of paraoxon. Reduced glutathione has little or no effect on paraoxon degradation by either microsomal or soluble enzymes. Actinomycin D inhibits O-dealkylation of paraoxon in vivo, as indicated by reduction of 14CO2 formation, and in vitro, as indicated by decreased activity of microsomal O-dealkylase. The role of microsomal mixed-function oxidases and NADPH-dependent O-dealkylase in the metabolism of organophosphorus insecticides is discussed. 相似文献
3.
杨梅叶抑菌活性成分初步分离与鉴定 总被引：3，自引：1，他引：2
用石油醚、氯仿、乙酸乙酯和正丁醇分别对杨梅叶甲醇提取物进行了萃取,得不同萃取相。测定了其对番茄灰霉病菌Botrytis cinerea、番茄早疫病菌Alternaria solani、水稻立枯丝核Rhizoctonia solani、小麦禾谷镰刀菌Fusarium graminearum、 黄瓜炭疽病菌Colletotrichum lagenarium、玉米大斑病菌Setosphaeria turcica等植物病原菌的抑菌活性。结果表明,乙酸乙酯相和正丁醇相的抑菌活性较好。对乙酸乙酯相进一步分离得到7个化合物,经电喷雾质谱(ESI-MS)、核磁共振氢谱(1H NMR)和碳谱(13C NMR)鉴定其分别为已知化合物山楂酸( 1 )、3-O-反-对-香豆酰基马斯里酸( 2 )、3-O-没食子酰二氢杨梅素( 3 )、斛皮素-7-O-鼠李糖甙( 4 )、杨梅素3-O-鼠李糖甙( 5 )、杨梅素-3-O-鼠李糖(3-O-没食子酰)甙( 6 )和杨梅素-3-O-鼠李糖(2-O-没食子酰)甙( 7 )。孢子萌发法测定结果表明,化合物 3~6 对番茄灰霉病菌和玉米大斑病菌的孢子萌发具有较好的抑制作用,EC50值分别在3.44~4.59 mg/L和8.85~11.6 mg/L之间。 相似文献
4.
为了明确活性氧（reactive oxygen species,ROS）代谢在甜瓜抗病性诱导中的作用,以抗白粉病甜瓜品种Tam Dew和感病品种卡拉克赛幼苗为材料,通过盆栽试验研究了苯丙噻二唑（BTH）喷雾或白粉菌接种后甜瓜叶片超氧阴离子（O2.-）产生速率、过氧化氢（H2O2）含量及超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、苯丙氨酸解氨酶（PAL）活性的变化。BTH处理或白粉菌接种均可诱导甜瓜叶片SOD、PAL活性升高,抑制CAT活性,导致叶组织O2.-产生速率和H2O2含量增加,BTH喷雾＋白粉菌接种比二者单独处理效果更好。结果表明,BTH处理后叶片O2.-产生速率提高和H2O2积累是甜瓜抗白粉病能力提高的重要机制,BTH通过诱导ROS代谢酶活性调节H2O2含量,且BTH诱导的甜瓜抗病性与品种的基础抗性有关。 相似文献
5.
Keshav Birla Viviana Rivera-Varas Gary A. Secor Mohamed F. R. Khan Melvin D. Bolton 《European journal of plant pathology / European Foundation for Plant Pathology》2012,134(3):475-488
Cercospora leaf spot (CLS), caused by the fungal pathogen Cercospora beticola, is the most important foliar disease of sugar beet worldwide. Control strategies for CLS rely heavily on quinone outside inhibitor (QOI) fungicides. Despite the dependence on QOIs for disease control for more than a decade, a comprehensive survey of QOI sensitivity has not occurred in the sugar beet growing regions of France or Italy. In 2010, we collected 866 C. beticola isolates from sugar beet growing regions in France and Italy and assessed their sensitivity to the QOI fungicide pyraclostrobin using a spore germination assay. In total, 213 isolates were identified with EC50 values greater than 1.0???g?ml?1 to pyraclostrobin, all of which originated from Italy. To gain an understanding of the molecular basis of QOI resistance, we cloned the full-length coding region of Cbcytb, which encodes the mitochondrial QOI-target enzyme cytochrome b in C. beticola. Cbcytb is a 1,162-bp intron-free gene with obvious homology to other fungal cytb genes. Sequence analysis of Cbcytb was carried out in 32 QOI-sensitive (<0.080???g?ml?1) and 27 QOI-resistant (>1.0???g?ml?1) isolates. All tested QOI-resistant isolates harboured a point mutation in Cbcytb at nucleotide position 428 that conferred an exchange from glycine to alanine at amino acid position 143 (G143A). A PCR assay developed to discriminate QOI-sensitive and QOI-resistant isolates based on the G143A mutation could detect and differentiate isolates down to approximately 25?pg of template DNA. Microsatellite analyses suggested that QOI resistance emerged independently in multiple genotypic backgrounds at multiple locations. Our results indicate that QOI resistance has developed in some C. beticola populations in Italy and monitoring the G143A mutation is essential for fungicide resistance management in this pathosystem. 相似文献
6.
7.
The fate of prothiofos (O-2,4-dichlorophenyl O-ethyl S-propyl phosphorodithioate) were studied in male rats 1, 3, 8, 24, 48, and 120 hr after oral administration. In the determination of prothiofos by gas chromatography-mass spectrometry, pentadeuteroethoxy-labeled prothiofos was used as the internal standard and the carrier of residual prothiofos. Prothiofos was rapidly absorbed from the small intestine and had substantially disappeared from the gastrointestinal tract within 24 hr after dosing. The residual concentrations of prothiofos in all organs analyzed, reached a maximum at 3 hr after dosing, and then diminished exponentially. The major urinary metabolites were 2,4-dichlorophenol (21% of administered prothiofos), its conjugated substances (26%), O-2,4-dichlorophenyl O-ethyl hydrogen phosphorothioate (14%), and O-2,4-dichlorophenyl O-ethyl hydrogen phosphate (25%). While prothiofos was found in the feces (3.8%), prothiofos oxygen analog (prothiofos-oxon) was scarcely detected in any excreta. Results obtained with a single dosing of prothiofos-oxon indicated that the oxygen analog formed from prothiofos in vivo was rapidly degraded through cleavage of the PS bond and the liberation of 2,4-dichlorophenol. The low mammalian toxicity of prothiofos is probably due to depropylthiolation in the molecule. 相似文献
8.
In vitro and in vivo experiments with Sprague-Dawley rats showed that the three organophosphate insecticides tested (see below) depressed endogenous corticosterone synthesis and blocked corticosteroidogenesis in response to ACTH and cAMP stimulation of a suspension of adrenal cells. Pregnenolone stimulation of adrenal cells was not inhibited at the insecticide concentrations which blocked the ACTH and cAMP stimulation of corticosteroidogenesis. It was concluded that the insecticides act beyond the site of action of ACTH and at or beyond the level of cAMP metabolism and prior to the metabolism of pregnenolone.Insecticides tested were: dichlorvos (O,O-dimethyl-O,2,2-dichlorovinyl phosphate), Dursban (phosphorothioic acid: O,O-diethyl O-3,5,6-trichloro-2-pyridyl ester), and Diazinon (phosphorothioic acid: O,O-diethyl O-(2-isopropyl-6-methyl-4-pyrimidinyl ester). 相似文献
9.
Richard T. Mayer John W. Jermyn M.Danny Burke Russell A. Prough 《Pesticide biochemistry and physiology》1977,7(4):349-354
Methoxy-, ethoxy-, propoxy-, and butoxyresorufin were prepared and tested as substrates for the fluorometric assay of O-dealkylation by the mixed-function oxidase system in house flies, Musca domestica L. Methoxyresorufin proved to be the most suitable substrate because of the favorable reaction rates. This sensitive assay can be performed with a minimum of microsomal protein (<0.3 mg/ml) in 5 min or less. The apparent Km and maximum velocity were calculated as 2.88 μM and 0.27 nmol of resorufin produced/min/mg of microsomal protein, respectively. The O-dealkylation reaction required O2 and NADPH and was inhibited by CO. 相似文献
10.
以对霜霉病不同抗性的葡萄品种左优红和霞多丽为材料,利用分子生物学和植物生理学试验手段,结合药理学试验,探讨葡萄在应答霜霉病过程中葡萄多磷酸肌醇激酶基因（VvIPK2）和H2O2的作用机制。接种霜霉病菌后15 h葡萄叶片VvIPK2表达量是正常水平的12倍,接种后3 hH2O2含量达最大值,同时苯丙氨酸解氨酶和几丁质酶活性升高;多磷酸肌醇激酶（IPK2）抑制剂、外源H2O2及H2O2清除剂均能改变霜霉病菌所引起的抗性葡萄品种左优红叶片PAL和几丁质酶活性的变化,同时可以影响不同抗性品种叶片的感病情况;IPK2抑制剂对葡萄霜霉病菌引起的H2O2水平变化没有影响;清除H2O2可减弱葡萄霜霉病菌对VvIPK2表达量的诱导效应。研究表明H2O2位于IPK2的上游,通过调控PAL和几丁质酶活性参与葡萄应答霜霉病过程。 相似文献
11.
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. 相似文献
12.
《Pesticide biochemistry and physiology》2009,95(2-3):68-72
The marine cyanobacterium Phormidium valderianum BDU 20041 is able to dwell and grow in the presence of chlorpyrifos (O,O-diethyl-O-[3,5,6-trichloro-2-pyridyl] phosphorothioate), a phosphorothioate insecticide, at a concentration of 45 ppm. Chlorpyrifos exposure resulted in stunted growth of P. valderianum, and a 48-h exposure revealed increase in activity of pesticide-metabolizing enzymes, such as polyphenol oxidase, catalase, superoxide dismutase, esterase, and glutathione S-transferase. Among the three classes of esterases P. valderianum BDU 20041 was found to use esterases A in the metabolization of chlorpyrifos. Increased activity of catalase and superoxide dismutase clearly depicted the provoked state of oxidative stress, concurrently this circuitously proving the triggered mode of reactive oxygen species mediated degradation of chlorpyrifos. 相似文献
13.
The synergistic effect of triphenyl phosphate (a carboxyesterase inhibitor), sesamex (inhibitor of microsomal oxidation) and O,O-diethyl O-phenyl phosphorothioate on the toxicity of malathion and malaoxon for one susceptible and two resistant strains of housefly was studies. It was found that in the resistant strain G (characterized by high carboxyesterase activity) both malathion and malaoxon were synergized by triphenyl phosphate, but only malaoxon (and not malathion) by sesamex. The other resistant strain E 1, moderately tolerant for malathion but highly resistant to malaoxon, differed from strain G in that triphenyl phosphate had no effect; its response to sesamex was similar to that of strain G. The third synergist, O,O-diethyl O-phenyl phosphorothioate, combined the properties of triphenyl phosphate and sesamex. It was found to be the best of the three compounds used.Biochemical in vitro studies showed that both resistant strains could degrade malaoxon oxidatively at a rate at least 10 × higher than that of the susceptible strain. This oxidation could be inhibited by very low concentrations of the thiono analogue; a malaoxon to malathion ratio of 10:1 gave an inhibition of about 70% at a malaoxon concentration of 5 × 10?6M. The product of this oxidation is malaoxon β-monocarboxylic acid. This metabolite was also found 1 hr after application of malaoxon in vivo.The results mentioned in this paper indicate that houseflies may become resistant to malaoxon by an increased rate of oxidative carboxyester bond cleavage. 相似文献
14.
《Physiological and Molecular Plant Pathology》1999,54(5-6):131-143
An oxidative burst was previously demonstrated to be induced in tomato plants by race specific elicitors of the fungal pathogen Cladosporium fulvum . The in planta levels of H2O2estimated to occur during elicitor treatment, were compared with the levels required to show toxicity to host cells and to the fungal pathogen. Injection of Cf-9 tomato leaves with 100 m m H2O2caused an insignificant degree of necrosis and 1m H2O2was required to cause complete leaf necrosis comparable to that induced by the AVR9 elicitor. Assays with Cf-5 tomato cell suspensions confirmed the low toxicity of H2O2to tomato cells but, as expected, the addition of Fe2+with H2O2(or with intercellular fluids containing AVR5 elicitor) enhanced cell death as determined by the Evans Blue assay. Germination and germ tube growth of conidia of C. fulvum were significantly retarded by 4–5 m m H2O2, and at higher concentrations, death of germ tubes was observed (ED50=22 m m), as determined by the fluorescein diacetate assay. The addition of Fe2+with H2O2had little effect on fungal growth or viability in vitro . These results suggest that the amount of H2O2accumulating during an elicitor-induced response in leaves may be sufficient to affect fungal colonization but not to affect viability of host cells unless the Fe2+status in the apoplast is in some way altered by the elicitor to facilitate OH.production via the Fenton reaction. 相似文献
15.
Ilse Foissner 《Pesticide biochemistry and physiology》1984,22(3):346-348
Long-term experiments with dactyl cells of Nitella flexilis showed that the herbicide 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) at a concentration of 1 × 10?5M affected not only O2 evolution in the light but also O2 uptake in the dark. The inhibition of O2 production was transitory, but dark respiration did not recover. DCMU induced the formation of giant mitochondria which disappeared before cell death. It was concluded that the algicidic effect of 1 × 10?5M DCMU on N. flexilis, but not necessarily the elongation of mitochondria, was due to the inhibition of mitochondrial respiration and not of photosynthesis. 相似文献
16.
Foliar injury responses of 24 bean cultivars (Phaseolus vulgaris) to various concentrations of ozone
A. E. G. Tonneijck 《European journal of plant pathology / European Foundation for Plant Pathology》1983,89(3):99-104
In the summer of 1981, symptoms on leaves of field grown beans (Phaseolus vulgaris) were noticed suggesting O3 injury. In order to determine their relative sensitivity primary leaves of 24 bean cultivars were exposed to various concentrations of O3. Differences in foliar injury responses between cultivars were affected by O3 concentration. The cultivars Pros/Gitana and Stratego were the most sensitive, whereas Berna and Narda were the most insensitive. The symptoms observed in practice may be attributed to O3. Sensitivity of Stratego primary leaves clearly depended on plant age. This cultivar will be tested as an indicator plant for O3. 相似文献
17.
Jan Hendrik Reinders Larry G. Hansen Robert L. Metcalf Robert A. Metcalf 《Pesticide biochemistry and physiology》1983,20(1):67-75
Inhibition of chicken brain neurotoxic esterase (NTE) by a series of O-halogenated-phenyl-O-alkyl phenylphosphonates was studied in vitro. The “apparent” activity was found to consist of “true” NTE (sensitive to mipafox) plus a minor mipafox-resistant component. The pI50 of O-(2,6-dichlorophenyl) O-methyl phenylphosphonate for “true” NTE was 6.65, whereas it was about 3 for mipafox-resistant hydrolysis of phenyl valerate. This compound is suitable as an alternative to mipafox in the assay of “true” NTE, whereas the use of leptophos oxon gives a less accurate measure. The ethoxy analogs are about as potent in vitro as the corresponding methoxy compounds. Leptophosoxon and ethoxyleptophosoxon are more potent in vitro inhibitors than desbromoleptophosoxon. Within a like group of chlorinated phenylphosphonates, a reasonable correlation between in vitro neurotoxic esterase inhibition of the oxon and in vivo delayed neurotoxic potential by the corresponding phosphonothionate exists. In vivo inhibition of “apparent” NTE from chicken brain, studied 24 hr after an oral dose, is dose dependent for leptophos, ethoxyleptophos, and desbromoleptophos, the latter one being a very potent in vivo inhibitor. Ethoxyleptophos and leptophos have about equal in vivo esterase inhibitory properties. For desbromoleptophos and leptophos there is good agreement between the minimum dose causing delayed neurotoxicity and the dose leading to substantial inhibition of “apparent” NTE; ethoxyleptophos, on the other hand, inhibits the esterase at a dose much lower than the one which is neurotoxic. Several possible explanations for this discrepancy are considered. 相似文献
18.
A. R. Wasnikar S. K. Khatik M. L. Nayak S. K. Vishwakarma L. K. Punekar 《Phytoparasitica》1993,21(1):75-78
Biochemical analysis of betel leaves infected by leaf spot and blight caused byXanthomonas campestris pv.betlicola showed a decrease in moisture, chlorophyll, protein, phenol and total carbohydrate contents as compared with healthy leaves. The decrease in these five parameters was 31-42%, 29-70%, 20-79%, 30-53% and 53-87%, respectively. Application of 100 kg P2O5/ha gave maximum height of vine, number of leaves per vine and fresh weight of 100 leaves, as compared with treatments of 25, 50, 75 and 125 kg P2O5/ha. Except for 25 kg P2O5/ha, all treatments enhanced the keeping quality compared with the control (no P2O5). Incidence of bacterial leaf spot decreased significantly as phosphorus level increased. 相似文献
19.
TIA-230, O-[1-(4-chlorophenyl)-4-pyrazolyl] O-ethyl S-propyl phosphorothiolate, showed strong insecticidal activity against Spodoptera larvae, in spite of its weak in vitro anti-AChE activity. Head AChE of Spodoptera was, however, inhibited with the progress of TIA-230 intoxication. When the isolated central nerve cord was incubated with TIA-230, AChE in the tissue was strongly inhibited even by concentration (10?5M) lower than in vitro I50 against AChE (10?4M). The frequency of spontaneous firing of the nerve cord was increased by treatment of TIA-230 at low concentrations (10?6–10?5M) after a latent time of several minutes. The firing was increased by fenitroxon, but without the latent time. The length of the latent time agreed well with the time necessary for rising the inhibition of nerve cord AChE by TIA-230. AChE inhibition of TIA-230 in the nerve cord was reduced by the treatment of piperonyl butoxide, an inhibitor of mixed-function oxidases. From these results, TIA-230 was regarded as being activated oxidatively in the nerve cord to inhibit AChE. Profenofos was also activated in the nerve cord. It was concluded, therefore, that O-ethyl S-n-propyl phosphorothiolate insecticides were activated in the central nerve of the insect. 相似文献
20.
Chien-Jui Huang Yi-Hung Liu Ken-Haow Yang Chao-Ying Chen 《European journal of plant pathology / European Foundation for Plant Pathology》2012,134(1):1-12
Bacillus cereus C1L has been demonstrated to induce systemic disease resistance against Botrytis elliptica in lily. The objective of this study was to investigate physiological responses of B. cereus C1L-triggered systemic resistance in lily cv. Star Gazer against B. elliptica. By histological and biochemical analyses, leaves inoculated with B. elliptica displayed cell death, H2O2 accumulation and lignin deposition. As plants were elicited with B. cereus C1L, cell death, H2O2 accumulation and lignin deposition in leaves caused by B. elliptica infection were suppressed, revealing that suppression of oxidative burst might be associated with B. cereus C1L-induced systemic resistance. In reactive oxygen species inhibitors assays, B. elliptica-caused lesion numbers and H2O2 accumulation in lily leaves were significantly reduced as leaves were pretreated with catalase or diphenylene iodonium. Furthermore, the expression of LsGRP1 and LsPsbR in leaves elicited with B. cereus C1L and inoculated with B. elliptica was decreased. The same expression pattern was also observed in leaves pretreated with catalase or diphenylene iodonium and inoculated with B. elliptica. These results suggest that B. cereus C1L-induced systemic resistance may be related to suppression or alleviation of oxidative stress and cell death of lily caused by B. elliptica. 相似文献