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1.
J. Liu D. Macarisin M. Wisniewski Y. Sui S. Droby J. Norelli V. Hershkovitz 《Plant pathology》2013,62(4):820-828
Reactive oxygen species (ROS) play dual roles in plant–microbe interactions in that they can either stimulate host resistance or enhance pathogen virulence. Innate resistance in peach (Prunus persica) to the brown rot fungal pathogen Monilinia fructicola is very limited, and knowledge of the mechanism of virulence is rudimentary. In this study, production of hydrogen peroxide, a major component of ROS, was determined in peach flower petals in response to M. fructicola (a host pathogen) and Penicillium digitatum (a non‐host pathogen). Monilinia fructicola was able to infect flower petals while P. digitatum was not. During the host‐specific interaction, M. fructicola induced hydrogen peroxide accumulation in flower petals. Application of exogenous antioxidants significantly reduced hydrogen peroxide accumulation as well as the incidence of brown rot disease. Application of M. fructicola spores to the surface of intact flower petals induced gene expression and increased enzyme activity of NADPH oxidase and cell wall peroxidase in host tissues, resulting in the production of hydrogen peroxide. Petals inoculated with M. fructicola exhibited high levels of protein carbonylation and lipid peroxidation. No significant response in gene expression, enzyme activity or hydrogen peroxide levels was observed in peach flower petals treated with P. digitatum. These results suggest that M. fructicola, as with other necrotrophic fungi, uses the strong oxidative response as part of a virulence mechanism. 相似文献
2.
苏云金芽孢杆菌晶体蛋白对北方根结线虫生物测定方法的建立和杀虫效果评价 总被引：1，自引：0，他引：1
A bioassay procedure was developed to assess the toxicity of Bacillus thuringiensis crystal protein against Meloidogyne hapla,a root-knot nematode,under laboratory conditions.Reproducibility and precision of the bioassay results were optimal when forty 2nd stage juveniles were incubated in the dissolved crystal protein solution at 25℃,pH9.0 for 7 days.The juveniles were stained with 1% KMnO4 for 2 hours or methylene blue solution for 1 hour to distinguish living and dead ones.By the bioassay procedure,the LC50 value of strain YBT-1532 crystal protein against M.hapla was determined as 0.304±0.086 mg/mL(LC50±1.96SE).Moreover,the strain YBT-1532 showed toxicity to Caenorhabditis elegans,a free-living nematode.All results indicated that YBT-1532 is a toxic strain to plant-parasitic nematode,and has the potential to control plant-parasitic nematode. 相似文献
3.
实验旨在研究不同种植模式、作物种间不同的根部隔离处理对线辣椒根际与非根际土壤微生物数量、土壤酶活性及土壤养分有效含量的影响。结果表明：套作栽培的线辣椒根际、非根际土壤微生物数量、酶活性均高于单作栽培。与膜隔处理相比,网隔与无隔处理的根际、非根际土壤微生物数量及酶活性均有提高,其中以网隔处理最高。各处理根际土壤有机质、有效磷、有效钾含量均低于非根际土壤,但碱解氮含量表现为根际土壤高于非根际土壤。网隔处理中尼龙网减缓了玉米根系对线辣椒根系营养的直接竞争,同时玉米根系根际效应使其根际、非根际土壤养分含量在所有处理中最高。土壤微生物主要类群数量是影响土壤酶活性主要因子,与土壤酶活性显著相关。有机质、碱解氮含量与土壤酶活性、微生物数量呈极显著相关,有效磷含量与土壤酶活性、微生物数量呈正相关。土壤真菌数量、脲酶活性与有效钾含量呈负相关。 相似文献
4.
玉米线辣椒套作对线辣椒根际、非根际土壤微生物、酶活性和土壤养分的影响 总被引：6，自引：0，他引：6
实验旨在研究不同种植模式、作物种间不同的根部隔离处理对线辣椒根际与非根际土壤微生物数量、土壤酶活性及土壤养分有效含量的影响.结果表明:套作栽培的线辣椒根际、非根际土壤微生物数量、酶活性均高于单作栽培.与膜隔处理相比,网隔与无隔处理的根际、非根际土壤微生物数量及酶活性均有提高,其中以网隔处理最高.各处理根际土壤有机质、有效磷、有效钾含量均低于非根际土壤,但碱解氮含量表现为根际土壤高于非根际土壤.网隔处理中尼龙网减缓了玉米根系对线辣椒根系营养的直接竞争,同时玉米根系根际效应使其根际、非根际土壤养分含量在所有处理中最高.土壤微生物主要类群数量是影响土壤酶活性主要因子,与土壤酶活性显著相关.有机质、碱解氮含量与土壤酶活性、微生物数量呈极显著相关,有效磷含量与土壤酶活性、微生物数量呈正相关.土壤真菌数量、脲酶活性与有效钾含量呈负相关. 相似文献
5.
Peter Y.K. Cheung Richard M. Roe Bruce D. Hammock Charles L. Judson Mary Ann Montague 《Pesticide biochemistry and physiology》1985,23(1):85-94
Alkaline-dissolved crystal δ-endotoxin from Bacillus thuringiensis var. israelensis (serovar H 14) was injected into mice and seven species of insects representing the orders Lepidoptera, Orthoptera, Coleoptera, Hemiptera, and Diptera. High in vivo toxicity, at 1 to 5 ppm (μg toxin/g body wet wt), was observed with mice and some insects, including some that are not sensitive to the toxin when administered orally. Neuromuscular effects were observed when the toxin was injected directly into the body cavity of the test animals. Biochemical studies suggested that different protein fragments within the crystal δ-endotoxin may be responsible for the majority of the mosquito larvacidal activity and the neurotoxic symptoms observed in larvae of Trichoplusia ni. 相似文献
6.
The mechanism of the entomocidal action of Bacillus thuringiensis var. israelensis (BTI) in Periplaneta americana has been studied. Cockroaches treated with the alkali-solubilized BTI crystal gradually became sluggish and immobile. A physiological examination of poisoned cockroaches indicated that BTI possessed both myotoxic and neurotoxic activity. Following hemocoel or foregut administration of BTI, myotoxic effects were observed within 10–20 min whereas the onset of neurotoxic effects was considerably delayed. The results of this study suggest that the myotoxic action of BTI is probably important for the initial manifestation of its toxicity. The neurotoxic effects of BTI were ascribed to its ability to interfere with transmitter release. BTI exerted a dual action on transmitter release in the cockroach sixth abdominal ganglion. At lower doses (2–4 μg/ml) BTI was found to suppress transmitter release by interfering with calcium uptake. At higher concentrations (12 μg/ml or higher), however, BTI caused blockage of synaptic transmission which was preceded by massive transmitter release. In either case, the synapse blocking action of BTI was probably due to its effects upon presynaptic terminals. Postsynaptic membranes and axons in the ventral nerve cord apparently remained unaffected. 相似文献
7.
8.
The relative toxicity (μg a.i. g?1 body wt) of the formamidine insecticide chlordimeform (CDM) and the triazapentadiene insecticide amitraz was examined in two species of noctuid moth Spodoptera littoralis and Heliothis virescens. When applied topically, there was an unexpected and marked difference in the toxicity of CDM base and its hydrochloride to adults of both species, the salt being appreciably more toxic. For H. virescens at least, this difference in toxicity could not be explained by differences in penetration. This trend was reversed for larval instars of S. littoralis; while there was relatively little difference in the toxicity of the base to adult and larval stages, the salt was at least 1000-fold more toxic to adults than to larvae. N1-Demethylchlordimeform (DCDM) was the only metabolite of CDM to show biological activity against either species, but was much less toxic than the parent compound. Amitraz was far less toxic than either CDM or DCDM; like the CDM salt, it appeared to be more toxic to adult than larval stages of S. littoralis. Application of piperonyl butoxide significantly increased the toxicity of the CDM salt, DCDM and amitraz to adult H. virescens, the synergist being particularly effective with DCDM and amitraz. In contrast, piperonyl butoxide had no significant effect on the toxicity of DCDM, and slightly antagonised the toxicity of DCDM to fourth-instar larvae of S. littoralis. 相似文献
9.
It had been found earlier that the chloronicotinyl insecticide thiacloprid (as the 480 g litre(-1) SC Calypso) poses a favourably low toxicity hazard to the honeybee, Apis mellifera L. As with pyrethroids, the metabolization of chloronicotinyl compounds involves monooxygenases, which are known to be inhibited by some ergosterol biosynthesis inhibitor (EBI) fungicides potentially co-applied with these insecticides. The potential synergistic enhancement of the toxicity of thiacloprid to honeybees when co-applied with such fungicides was therefore studied under laboratory and semi-field conditions. Fungicides of other chemical classes were also examined for synergistic potential to reveal other metabolic interactions. In the laboratory, only a slight synergistic effect was observed with the anilinopyrimidine fungicide examined, while a significant enhancement of thiacloprid toxicity to honeybees was found with EBI fungicides. In three tunnel tests conducted under different environmental conditions to simulate field exposure, no increased mortality was observed when honeybees were directly sprayed with thiacloprid (Calypso) alone or in combination with the EBI fungicide tebuconazole (250 g litre(-1) EW, Folicur). There was also no synergized reduction in the foraging intensity on the treated crop. In general, the foraging intensity decreased after thiacloprid treatment but was restored within 24-48 h. The hive vitality was not affected by either thiacloprid or its tank mix with tebuconazole. Our results suggest that, at the recommended use rates, thiacloprid poses a negligible lethal risk to honeybees when applied either alone or in tank mixes with fungicides of various chemical classes. 相似文献
10.
六种杀虫剂对小地老虎的毒力及对土壤生物安全性评价 总被引：6，自引：3，他引：3
为筛选出高效安全的土壤处理杀虫剂,室内采用浸叶法比较了3种新杀虫剂与3种已登记的杀虫剂对小地老虎的毒力,同时用人工土壤法和密闭法分别测定了6种药剂对蚯蚓的急性毒性和对土壤呼吸强度的影响。结果显示,溴虫腈、茚虫威和甲维盐对小地老虎3龄幼虫的毒力明显高于3种已登记药剂毒死蜱、辛硫磷和高效氯氟氰菊酯;溴虫腈、茚虫威和甲维盐对蚯蚓的LC50分别为1320．80、1153．42和167．91mg／kg,均低于其它3种药剂,属于低毒级;供试杀虫剂中以溴虫腈对小地老虎和蚯蚓的毒力选择性最高,其毒力选择性比值（蚯蚓LC50／小地老虎LC50）为7115．23;6种药剂对土壤微生物均无危害性。 相似文献
11.
《Pesticide biochemistry and physiology》1986,26(2):202-208
Acute intraperitoneal toxicity of mipafox, paraoxon, and soman was highest in chicken, followed by rat, and lowest in frog. Species differences in organophosphorus toxicity were not related to differences in the specific activities of either acetylcholinesterase or carboxylesterase in brain. The sensitivity to inhibition of brain acetylcholinesterase in vitro by the organophosphorus compounds was closely related to the susceptibility of the species to acute organophosphorus poisoning. Both the acute toxicity and the sensitivity of brain acetylcholinesterase to inhibition in vitro by organophosphorus compounds in all the species were in the following order of increasing activity: mipafox < paraoxon < soman. The sensitivity of brain carboxylesterase to inhibition by the organophosphorus compounds were less than that of acetylcholinesterase and it could not be related to species susceptibility to acute organophosphorus toxicity. Paraoxon-insensitive phenyl valerate hydrolase in chicken brain was more sensitive to inhibition by mipafox and soman compared to rat; in chicken the sensitivity of paraoxon-insensitive phenyl valerate hydrolase to inhibition by soman was 9000 times more than that by mipafox, while in rat it was 100 times more. Frog brain had no paraoxon-insensitive phenyl valerate hydrolase activity. No evidence of age dependence was noticed in the specific activities of brain acetylcholinesterase, carboxylesterase, neurotoxic esterase, and paraoxon-insensitive phenyl valerate hydrolase or in the sensitivity of these enzymes to in vitro inhibition by organophosphorus compounds in both rats and chickens. 相似文献
12.
Human membrane drug transporters are recognized as major actors of pharmacokinetics. Pesticides also interact with human drug transporters, which may have consequences for pesticide toxicokinetics and toxicity. The present review summarizes key findings about this topic. In vitro assays have demonstrated that some pesticides, belonging to various chemical classes, modulate drug transporter activity, regulate transporter expression and/or are substrates, thus bringing the proof of concept for pesticide‐transporter relationships. The expected low human concentration of pesticides in response to environmental exposure constitutes a key‐parameter to be kept in mind for judging the in vivo relevance of such pesticide‐transporter interactions and their consequences for human health. Existing data about interactions of pesticides with drug transporters remain, however, rather sparse; more extensive and systematic characterization of pesticide‐transporter relationships, through the use of high throughput in vitro assays and/or in silico methods, is, therefore, required. In addition, consideration of transporter polymorphisms, pesticide mixture effects and physiological and pathological factors governing drug transporter expression may help to better define the in vivo relevance of pesticide‐transporter interactions in terms of toxicokinetics and toxicity for humans. © 2019 Society of Chemical Industry 相似文献
13.
The aim of this study was to evaluate the effects of different N-acetylcysteine doses on the tolerance to fenthion-induced oxidative stress, alterations in glutathione metabolism and cholinesterase specific activities in the liver by using freshwater fish Cyprinus carpio (Cyprinidae) as a model organism. An acute toxicity study was carried out to determine 96-h median lethal concentration of fenthion for this species (2.16 mg/L) and 80% of this concentration was applied in toxicity studies. Four groups, each containing eight fish were constituted as follows: Control group, fenthion treated group, 0.5 or 400 mg/kg NAC-injected + fenthion-treated groups. Biochemical analyses were carried out spectrophotometrically. Fenthion treatment significantly decreased total glutathione and glutathione levels, glutathione/glutathione disulfide ratio together with glutathione reductase and γ-glutamylcysteine synthetase specific enzyme activities. The higher dose of N-acetylcysteine increased the toxic effects of fenthion and γ-glutamyl transpeptidase specific activity while decreasing glutathione S-transferase specific activity. However, injection of the lower dose provided a limited protection against fenthion toxicity. In all exposure groups, lipid peroxidation increased and total protein levels decreased, while protein depletion was prevented by low dose of N-acetylcysteine application. Acetylcholinesterase and butyrylcholinesterase activities were at similar levels in the liver of C. carpio. A dose-dependent inhibition was observed in butyrylcholinesterase activity by N-acetylcysteine application. The results showed that fenthion had a significant oxidative stress inducing potential through the reduction of glutathione redox capacity. The critical point for overcoming oxidative stress by N-acetylcysteine in fenthion toxicity was the selection of the dose; N-acetylcysteine exerted its toxic effects by means of oxidative stress in fish liver at the higher dose. 相似文献
14.
《Pesticide biochemistry and physiology》1986,25(1):19-30
The effects of intravenous administration of non-cyano (cis-permethrin) and cyano-substituted (deltamethrin) pyrethroids were studied on spontaneous and evoked ventral root activity in rat spinal cord and on spontaneous firing of ventral horn interneurons in the cat. Both pyrethroids had dramatic facilitatory effects on spontaneous firing rates of ventral roots and spinal interneurons and increased the amplitude of mono- and polysynaptically mediated ventral root responses to dorsal root stimulation. Spontaneous and evoked afferent sensory activity was slightly enhanced by cis-permethrin, but not by deltamethrin. In the cat diazepam (0.5 mg/kg, iv) was equally effective in antagonizing the facilitation of interneuronal firing resulting from either deltamethrin or cis-permethrin. These effects of pyrethroids on spinal neurons may underly the production of tremor and choreoathetosis-salivation toxicity symptoms in mammals. 相似文献
15.
Natural history of Arabidopsis thaliana and oomycete symbioses 总被引：1，自引：1，他引：0
Eric B. Holub 《European journal of plant pathology / European Foundation for Plant Pathology》2008,122(1):91-109
Molecular ecology of plant–microbe interactions has immediate significance for filling a gap in knowledge between the laboratory
discipline of molecular biology and the largely theoretical discipline of evolutionary ecology. Somewhere in between lies
conservation biology, aimed at protection of habitats and the diversity of species housed within them. A seemingly insignificant
wildflower called Arabidopsis thaliana has an important contribution to make in this endeavour. It has already transformed botanical research with deepening understanding
of molecular processes within the species and across the Plant Kingdom; and has begun to revolutionize plant breeding by providing
an invaluable catalogue of gene sequences that can be used to design the most precise molecular markers attainable for marker-assisted
selection of valued traits. This review describes how A. thaliana and two of its natural biotrophic parasites could be seminal as a model for exploring the biogeography and molecular ecology
of plant–microbe interactions, and specifically, for testing hypotheses proposed from the geographic mosaic theory of co-evolution. 相似文献
16.
Cry1Ba3是由本实验室发掘的对小菜蛾有高毒力的杀虫晶体蛋白。为了寻找对杀虫活性有重要影响的氨基酸,为杀虫机理研究和改造杀虫蛋白提供理论依据,本研究利用Ple Bio Informatique Lyonnais数据库对Cry1Ba3的二级结构进行模拟;采用BioEdit软件分析Cry1Ba3的疏水区;将Cry1Ba3与Cry1Aa1、Cry2Aa1、Cry3Aa1以及Cry4Ba1进行多序列比对,从而确定了20个氨基酸突变位点。利用半重叠引物PCR的方法对Cry1Ba3进行定点突变,将突变体在大肠杆菌BL21中进行诱导表达。通过浸叶法对各个突变蛋白杀小菜蛾的生物活性进行测定。获得的20个Cry1Ba3突变体均能在大肠杆菌BL21中表达,并以包涵体形式存在。杀虫活性测定结果表明M6(R192L)、M10(W303A)、M19(H485G)对小菜蛾的活性明显降低,二级结构预测表明活性降低的突变蛋白的构象均发生明显变化,其余17种突变蛋白的活性和二级结构都没有明显变化。说明第192位的精氨酸、第303位的色氨酸和第485位的组氨酸对Cry1Ba3的杀小菜蛾活性有重要影响,上述3个位点氨基酸突变引起的蛋白活性减低可能与毒素的空间结构变化有关。 相似文献
17.
Summary. Herbicide combinations containing paraquat were synergistic and provided control of established Agropyron repens (L.) Beauv. (quackgrass) sods for the entire growing season. Paraquat applied at 0–5 lb/ac with simazine or diuron at 4–0 lb/ac was more phytotoxic than either herbicide applied singly and the enhanced activity was more than additive. This synergism was not due to increased absorption or translocation of either herbicide in aerial portions of the plant. Paraquat applied to the shoot increased the susceptibility of quackgrass to simazine action through the soil. Pre-treatment of quackgrass with aminotriazole or amitrole-T at 10 lb/ac 7 days before paraquat application at 0–5 lb/ac provided increased toxicity over that obtained when the two herbicides were applied together or singly. Subsequent studies indicated that aminotriazole applications prior to shoot destruction by either paraquat or clipping resulted in more chronic aminotriazole toxicity. Using methyl-14C-paraquat it was found that aminotriazole pre-loading also increased the movement of paraquat in and out of the treated leaf. This increase was even more pronounced with amitrole-T. When the two herbicides were applied together, antagonism in absorption and translocation occurred. Action synergique de combinaisons d'herbicides comprenant du paraquat sur Agropyron repens (L.) Beauv. 相似文献
18.
不同强度放牧后沙质草场土壤微生物的分布特征 总被引：6，自引：1，他引：5
本文通过对科尔沁沙质草场不同强度放牧后围栏封育过程中表层(0-5cm)和亚表层(5-15cm)土壤微生物及土壤因子的研究表明:不同放牧强度围栏内,土壤微生物总数表现出:轻牧区>中牧区>对照区>重牧区>自由放牧区,11年的围栏封育不能使不同放牧强度下的沙质草场恢复到相同水平;亚表层土壤的细菌、真菌和放线菌数量、pH、电导率和含水量均大于表层土壤。轻牧和中牧有利于微生物各类群的生长繁殖,过度放牧会抑制微生物的活动,一直自由放牧则会严重破坏沙质草场表层土壤,使其微生物数量和土壤含水量减少,土壤碱性增强。 相似文献
19.
Induction of the microsomal oxidase system by dietary phenobarbital and β-naphthoflavone was examined in three blowflies, Phormia regina (Mg.), Lucilia illustris (Mg.), and Eucalliphora lilica (Walk.). Responses were similar in adults and larvae of all species. Phenobarbital increased cytochrome P-450 levels up to 9-fold and aldrin epoxidase up to 138-fold. Increases in cytochrome P-450 and aldrin epoxidase caused by β-naphthoflavone were minor relative to those produced by phenobarbital. In toxicity experiments with carbaryl and propoxur tolerance was associated with the amount of microsomal oxidase activity. Using piperonyl butoxide to synergize carbaryl and propoxur there was no clear indication for the use of either the synergist ratio or synergist difference as an indicator of microsomal oxidase activity. 相似文献