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1.
Isolated spinach (Spinacia oleracea L.) chloroplasts contain a Mg+2-dependent ATPase that is activated by light in the presence of dithiothreitol (DTT) and phenazine methosulfate (PMS). Effects of 11 herbicides, known to affect photophosphorylation in isolated chloroplasts, were measured on ATPase activity when added prior to illumination, on the postillumination dark activity of the ATPase, and on the light-induced synthesis of ATP mediated by DTT and PMS.When added prior to illumination, activity of the ATPase was stimulated by low, and inhibited by high, molar concentrations of chlorpropham, dicryl, dinoseb, ioxynil, oryzalin, perfluidone, propanil, and 4,6,7-trichloro-2-(trifluoromethyl)benzimidazole (TCTFB). The light activation of the ATPase was not affected by diuron, bromacil, or atrazine. Perfluidone, dinoseb, ioxynil, and TCTFB stimulated, whereas chlorpropham, dicryl, oryzalin, propanil, atrazine, bromacil, and diuron had no effect on postillumination hydrolytic activity. The light-induced synthesis of ATP mediated by DTT and PMS was inhibited strongly by chlorpropham, dicryl, dinoseb, ioxynil, oryzalin, perfluidone, propanil, and TCTFB.Because the ATPase reactions are considered to represent the reversal of the terminal reactions of photophosphorylation, inhibition of these reactions implies that the compounds tested, except for diuron, atrazine, and bromacil, have a site of action on the ATP-generating pathway that is separate from the site involved in the inhibition of the Hill reaction. 相似文献
2.
F.M. Ashton O.T. de Villiers R.K. Glenn W.B. Duke 《Pesticide biochemistry and physiology》1977,7(2):122-141
Time- and concentration-course studies were conducted to determine the effect of thirteen herbicides on photosynthesis, respiration, RNA synthesis, protein synthesis, and lipid synthesis using isolated single leaf cells. Each herbicide was from a different chemical class. Appropriate 14C-substrates and product purification procedures were used for each process prior to liquid scintillation counting. The most sensitive metabolic site of inhibition was photosynthesis for atrazine, bromacil, dichlobenil, monuron, and paraquat; RNA synthesis for dalapon and dinoseb; protein synthesis for chlorpropham; and lipid synthesis for CDAA, chloramben, 2,4-D, EPTC, and trifluralin. However, with several herbicides, one or more process was almost as sensitive as the one mentioned above. All herbicides inhibited more than one process, and the most sensitive site of inhibition may not be the same process that was inhibited the greatest at the maximum concentration and maximum exposure time used. Therefore, a concept of metabolic sites of action, rather than a primary site of action, appears to be more meaningful for herbicides. 相似文献
3.
The effects of acifluorfen and oxyfluorfen on photosynthetic electron transport reactions of pea chloroplasts were compared with those induced by paraquat and monuron. Monuron inhibited electron flow between photosystems I and II, and paraquat acted as an electron acceptor for photosystem I, promoting superoxide formation by illuminated chloroplasts. Neither acifluorfen nor oxyfluorfen at concentrations up to 50 μM affected non-cyclic electron flow or promoted superoxide formation. Both herbicides were shown to repress ferredoxin-dependent NADP+ reduction by illuminated chloroplasts. Further experiments showed that, in the presence of ferredoxin-NADP+ reductase and chloroplast membranes maintained in the dark, p-nitro diphenyl ether (DPE) herbicides promoted the rate of ferredoxin-dependent oxidation of NADPH, implying that these herbicides can accept electrons from reduced ferredoxin. The interaction between acifluorfen, ferredoxin and chloroplast membranes was examined further by following the effect of this herbicide on the peroxidation of illuminated thylakoids. Lipid peroxidation was promoted by acifluorfen, although this effect was abolished if thylakoids were washed prior to use. The effect of washing could be reversed by adding exogenous ferredoxin. These data demonstrate that interaction of DPE herbicides with photosynthetic electron transport in the vicinity of ferredoxin is necessary for light-dependent herbicide activation. 相似文献
4.
The electron transport inhibition, uncoupling, and binding of ioxynil and bromoxynil salts is compared in chloroplast fragments isolated from two weed species with contrasting responses to the hydroxybenzonitriles. Ioxynil Na was three to four times more inhibitory than bromoxynil K towards DCPIP and SiMo reduction in both Matricaria inodora and Viola arvensis. Ioxynil Na was also a more potent uncoupler of PSI-dependent electron transport from ascorbate/DCPIP to methyl viologen. Uncoupling occurred at concentrations higher than those that inhibited electron transport. Binding studies with [14C]bromoxynil K and [14C]ioxynil Na salts revealed slightly biphasic curves with no significant difference in the amounts of the two herbicides bound at a given concentration. The ratios of inhibition constant (Ki) and binding constant (Kb) were approximately one for ioxynil Na and three for bromoxynil K. Radiolabelled herbicide displacement studies revealed that ioxynil Na could partially displace bound [14C]bromoxynil K, but bromoxynil K could not displace bound ioxynil Na at biochemically active concentrations. Ioxynil Na may be a more effective inhibitor than bromoxynil K because it binds more strongly to the thylakoid membrane. 相似文献
5.
Two approaches are suggested for the acceleration of the photocatalytic oxidation of organic contaminants of water: acceleration by oxidants and photo-enhancement by dyes. These processes were examined with several substances: two widely applied herbicides, bromacil (a uracil) and metribuzin (a triazine), and three proteins, studied as models of biocontaminated waters. The effects of oxygen and hydrogen peroxide indicated two different reaction patterns of photo-oxidation of the herbicides. With metribuzin, oxygen had a pronounced effect on the rate of photo-oxidation, while the influence of hydrogen peroxide was quite moderate; with bromacil, oxygen had a limited effect on the rate of photo-oxidation, which however was considerably enhanced by hydrogen peroxide. Acceleration of the photo-catalytic oxidation of colourless refractory contaminants by photo-excited dye was observed. Both UV and visible light were required for the enhanced decomposition. The mechanism of the reaction seems to involve a combination of oxidation by hydroxyl radicals, via the hole-electron semiconductor route, with subsequent oxidation of photo-intermediates by singlet oxygen formed by dye sensitization. The TiO2-photocatalyzed oxidation of proteins (albumin, ovalbumin and gamma-globulin) showed the susceptibility of proteins to photocleavage and of the amino acids to photocatalytic degradation. Tyrosine was the most sensitive, while the degradation of the aliphatic amino acids Gly and Asp was slow. 相似文献
6.
S. Cervelli P. Nannipieri G. Giovannini A. Perna 《Pesticide biochemistry and physiology》1975,5(3):221-225
The increased use of urea fertilizer and substituted ureas herbicides, the implication of soil urease in the effectiveness of urea applied as fertilizer, makes necessary to investigate their relationship.All herbicides investigated, fenuron, monuron, diuron, linuron, siduron and neburon are urease inhibitors. The inhibition constant value depends on molecular groups on the urea skeleton. There is a linear relationship between the Hammett sigma values and log Ki for fenuron, monuron and diuron.The presence of a large hydrophobic group and of one or two chlorine—an electron withdrawing group—on the phenyl ring of the herbicides molecule influences the Ki value.The hypothesis is proposed that the enzyme molecule reacts with inhibitors by means of the oxygen atom of the carboxyl group in the substituted ureas. 相似文献
7.
Long-term effects of herbicides on the photosynthetic membrane system were investigated. For this purpose the unicellular alga Bumilleriopsis filiformis was grown in liquid culture in the presence of sublethal concentrations of diuron, atrazine, metribuzin, and some substituted pyridazinones. This allowed reproducible growth conditions, exact dosing of herbicides, and also the preparation of functionally active cell-free photosynthetic systems. The electron transport system of cells grown in the presence of ureas and triazine derivatives is not impaired at all, wherea scultivation with pyridazinones damages their photosynthetic redox system. In addition, a strong bleaching effect is observed, whereas the first group of herbicides enhance chlorophyll formation. 相似文献
8.
Rates of carbon dioxide evolution and degradation rates of metamitron, metazachlor and metribuzin were measured in two soils in the presence of three microbial inhibitors. The nonselective microbial inhibitor sodium azide reduced both carbon dioxide evolution and the rate of loss of all three herbicides in both soils, although the reduction in degradation rate of metamitron was small. The antibacterial antibiotic novobiocin enhanced carbon dioxide evolution from both soils but had variable effects on the rates of herbicide degradation. It inhibited degradation of metazachlor and metribuzin, and in one of the soils its effects on metazachlor degradation were similar to those of sodium azide. Novobiocin inhibited degradation of metamitron to a small extent in one soil only. The antifungal antibiotic cycloheximide also enhanced carbon dioxide evolution from both soils. In general, its effects on herbicide degradation were similar to those of novobiocin, although the extent of inhibition was usually less pronounced. The results are discussed in terms of the relative involvement of microorganisms in degradation of the three herbicides. 相似文献
9.
Walter Oettmeier Klaus Masson Carl Fedtke Jörg Konze Robert R. Schmidt 《Pesticide biochemistry and physiology》1982,18(3):357-367
In chloroplasts isolated from susceptible and atrazine-resistant Amaranthus retroflexus, the inhibition of photosynthetic electron transport by various classes of herbicides has been investigated. Resistance of mutant Amaranthus is not restricted to s-triazines but also extends to uracils, 1,2,4-triazine-5-ones, and ureas. For 1,2,4-triazin-5-ones and chloroplasts of both biotypes, a correlation between inhibition of photosynthetic electron transport and the partition coefficient could be established. In the case of phenolic herbicides only modestly decreased or even higher sensitivity of chloroplasts from the resistant biotype as compared to the susceptible one could be observed. These results are confirmed by binding of radioactively labeled herbicides to chloroplasts of both plants. Specific binding of atrazine or metribuzin to resistant chloroplasts is completely abolished, and that of diuron or phenisopham diminished as compared to susceptible chloroplasts. In contrast, binding of phenolic herbicides generally is enhanced in resistant chloroplasts. Photoaffinity labeling of thylakoids from both biotypes by 2-azido-4-nitro-6-[2′,3′-3H]isobutylphenol yields almost identical labeling patterns. These results are consistent with a recently proposed model (W. Oettmeier, K. Masson, and U. Johanningmeier, Biochim. Biophys. Acta679, 376 (1982) of two different herbicide binding proteins at the reducing side of photosystem II: a 32- to 34-kdalton protein responsible for binding of triazines, triazinones, ureas, and related herbicides and a photosystem II reaction center protein for binding of phenolic herbicides. 相似文献
10.
The effect of acifluorfen and oxyfluorfen on chlorophyll bleaching, lipid peroxidation and photosynthesis in pea leaf discs was studied. Both her- bicides induced light-dependent bleaching and lipid peroxidation, the level of damage being greater at higher light intensities. Photosynthetic carbon dioxide fixation was only partially inhibited in treated leaf discs incubated in darkness, thus indicating that these herbicides did not inhibit photo- synthesis as a primary mode of action. Leaf discs maintained in darkness showed no visible signs of injury, and light-dependent herbicide-induced damage was reduced by incubating discs under nitrogen, orpre-incubating them with the electron-transport inhibitor monuron. It is suggested that acifluorfen and oxyfluorfen are activated by a light-dependent process, which requires photosynthetic electron transport. 相似文献
11.
Fenuron, monuron, diuron, siduron, linuron and neburon were tested for their inhibition of soil urease activity in order to investigate relationships between fertilizers and herbicides. The inhibition of urea hydrolysis in the selected soils was 10–33% for fenuron, 10–39% for monuron, 10–35% for diuron, 8–38% for siduron, 9–36% for linuron and 12–30% for neburon. In the field greater effects might be expected since the fertilizer/herbicide ratio would be lower than the one considered here. Some agronomic aspects of the relationship between fertilizers and herbicides are discussed. 相似文献
12.
M.M. Nemat Alla A.M. Badawi N.M. Hassan Z.M. El-Bastawisy E.G. Badran 《Pesticide biochemistry and physiology》2008,90(1):8-18
Application of the recommended field dose of metribuzin, butachlor and chlorimuron-ethyl to 10-days-old wheat and maize seedlings differentially reduced shoot fresh and dry weights during the following 16 days. Metribuzin was the most reductive while butachlor was the least. The herbicides slightly affected the activities of nitrate reductase (NR, EC 1.6.6.1) and nitrite reductase (NiR, EC 1.7.7.1) but greatly inhibited glutamine synthetase (GS, EC 6.3.1.2) and glutamate synthase (GOGAT, EC 1.4.7.1) activities. Meanwhile, there were significant accumulations of ammonia and soluble-N accompanied by diminutions in total-N and protein contents; metribuzin exerted the greatest changes. Additionally, aliphatic, aromatic and total amino acids in both species were mostly elevated by the three herbicides; however, valine, leucine and isoleucine were decreased by only chlorimuron-ethyl. These results could conclude that herbicides, particularly metribuzin, cause a shortage in ammonia assimilation and subsequently a decrease in protein formation. Moreover, the elevation of soluble-N and amino acids appeared to result from breakdown of the pre-existing protein, a state that seemed consistent in seedlings treated with metribuzin and, to some extent chlorimuron-ethyl but recovered in those treated with butachlor. 相似文献
13.
The effects of phosphine on electron transport and on some partial reactions of oxidative phosphorylation of mitochondria from mouse liver, housefly flight muscles and granary weevils has been studied. Phosphine was a strong inhibitor of respiration of mitochondria in the “active” state (state 3), uncoupled state, and ion-pumping state on glutamate, pyruvate plus malate, succinate, α-glycerophosphate, and ascorbate-cytochrome c as substrates. Respiration of mitochondria in state 3 was completely inhibited by about 250 μM phosphine. By contrast, the respiration of mitochondria in state 4 was much less sensitive. This inhibition could not be released by uncouplers suggesting that it is due to a direct effect on electron transport. Only site III was inhibited to any significant extent. Kinetic studies show that the inhibition was noncompetitive with Ki ranging from 1.6×10?5 to 7.2×10?5 depending on the source and purity of cytochrome oxidase. The inhibition of site III was also more pronounced in sonicated particles than in intact mitochrondria. The significance of this is discussed in relation to membrane sideness and topology of the components of the respiratory chain.Phosphine was unable to activate the “latent” ATPase nor did it have any inhibition of the Mg2+-simulated ATPase and only high levels (1.1 mM) showed modest inhibition (41%) of uncoupler-stimulated ATPase. Phosphine had no effect on the ATP-Pi exchange and on the ATP-ADP exchange reaction at concentrations causing strong respiratory inhibition. 相似文献
14.
The effect of the herbicides simazine (2)-chloro-4,6-bis (ethylamino)-s-triazine, ioxynil (4-hydroxy-3,5-diiodobenzonitrile) and 2,3,6-TBA(2, 3,6-trichlorobenzoic acid) on microbial activity and available plant nutrient content of an acid and an alkaline soil during an incubation period of six weeks under aerobic conditions has been studied in comparison with untreated soils. The herbicides were incorporated with the soils at normal application rates. At intervals determinations were made of carbon dioxide liberated, the content of ammonium and nitrate nitrogen and of available mineral plant nutrient elements. These quantities were not significantly influenced by the presence of 2,3,6-TBA :simazine stimulated microbial activity and ioxynil did so after an initial period of suppression. Both simazine and ioxynil retarded nitrification in the alkaline soil but increased it in the acid soil, attributed in part to stimulation of heterotrophic organisms. Biological oxidation of manganese was retarded by ioxynil but stimulated by simazine. Changes in the availability of some other plant nutrient elements were also found. 相似文献
15.
Romualdo Muoz Antonio Martinez-Martinez Alfonso Ros-Barcelo Ma Angeles Pedreo 《Pest management science》1990,28(3):283-288
The molecular action of herbicides with a triazine structure, such as atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) and metribuzin (4-amino-6-tert-butyl-3-methylthio-1,2,4-triazin-5(4H)-one), has been related to their inhibition of the electron carrier system between chloroplastic photosystems II and I. This report provides evidence that 4-amino-6-methyl-3-phenylamino-1,2,4-triazin-5(4H)-one, a recently synthesised triazine, structurally analogous to metribuzin, causes a powerful inhibition of the cell-wall lignification catalysed by peroxidase from lupin. The two reactions involved in this lignification process are: oxidative polymerisation of coniferyl alcohol and the generation of hydrogen peroxide at the expense of NADH oxidation. 相似文献
16.
The herbicides trifluralin, oryzalin, ioxynil, dichlofopmethyl, and dinoseb, and the fungicides chloraniformethan and dichlofluanid inhibited energy-dependent Ca2+ uptake in plant mitochondria at concentrations where they did not inhibit ADP phosphorylation and did not interfere with tubulin polymerization. We suggest as a common mechanism of action for these pesticides the inhibition of the regulation of cytoplasmic free Ca2+ concentration which may in turn lead to many physiological malfunctions. 相似文献
17.
K. CARPENTER HELEN J. COTTRELL W. H. DE SILVA B. J. HEYWOOD W. G. LEEDS K. F. RIVETT MARGERY L. SOUNDY 《Weed Research》1964,4(3):175-195
Summary. The preparation of ioxynil, bromoxynil, and their salts is described, and information on solubilities and stability to storage is summarized. Although the toxicology of the herbicides is to be reported in greater detail, a preliminary statement is made here. Evidence of herbicidat activity under glasshouse conditions is indicated briefly, and supports the conclusion that both compounds are effective when applied to the foliage of a wide range of dicotyledon weed species. Seedlings of some weed species resistant to the phenoxy alkanoic acids are controlled under glasshouse conditions at doses as low as 0.125 lb/ac, and ioxynil has a wider range of activity than bromoxynil at these low doses. Graminaceous species tolerate 4–8 lb/ac of both herbicides without injury, and certain leguminous crops tolerate one or other herbicide at doses of 0.5–0.75 lb/ac. The contact action of the herbicides is rapid, there are also slower systemic effects, and seed germination is inhibited. In susceptible species the level of post-emergence activity is shown to be influenced by the growth stage of the weed, the distribution of herbicide on the foliage, and environmental factors of which light intensity appears to be most important.
Propriétés chimiques et biologiques de deux nouveaux herbicides: ioxynil et bromoxynil 相似文献
Propriétés chimiques et biologiques de deux nouveaux herbicides: ioxynil et bromoxynil 相似文献
18.
Jos J. T. I. Boesten Leo J. T. Van Der Pas Johan H. Smelt 《Pest management science》1989,25(2):187-203
A model for the transport of pesticides in non-structured arable soil has been tested under field conditions. Three classes of sorption site are distinguished in the model. Sorption at class 1 sites is assumed to be at equilibrium whereas sorption at class 2 and class 3 sites is calculated using rate equations. Class 2 sites equilibrate on a time scale of days and class 3 sites equilibrate on a time scale of hundreds of days. In the model, the liquid phase is assumed to be homogeneous and completely mobile. The model was validated in two field experiments on a loamy sand soil using the herbicides cyanazine and metribuzin and using bromide ion as a tracer of liquid flow in soil. Ignoring sorption at class 3 sites resulted in large discrepancies between calculated and measured concentration profiles. Calculated concentration profiles were sensitive to the desorption rate constant for class 3 sites. 相似文献
19.
E. O. ETEJERE 《Weed Research》1982,22(6):313-318
The influence of foliar sprays of EPTC, fluorodifen and monuron on transpiration and photosynthetic oxygen output of Eupatorium odoratum plants is demonstrated. Foliar sprays with 100 ppm EPTC or monuron led to a significant decrease in transpiration for a continuous period of 14 days. Treatment with 100 ppm fluorodifen led to a noticeable increase in transpiration during the first eight days. All three herbicides significantly reduced photosynthetic oxygen output from the Eupaiorium plants. EPTC and monuron however, gave greatest effect. Reduction in transpiration from the plants was due to stomatal closure while reduction in photosynthetic oxygen output was due to both stomatal closure and probably also inhibition of the Hill reaction. 相似文献